A dental splint and method of manufacture

Abstract

A dental splint for providing a positional reference with respect to dentition of a subject. The splint comprising a frame having a first clamping element and a second clamping element movable with respect to the first clamping element to mechanically grip a first tooth of the subject; and a first extension arm rigidly attached to the frame and extending from the frame for supporting an optical reference unit at a location outside the oral cavity of the subject when the frame is gripping the first tooth. There is also provided a method for providing a positional reference with respect to dentition of a subject. The method comprising causing a dental splint as claimed in any preceding claim to grip a tooth of the subject; and imaging an optical reference unit carried by the or each extension arm of the dental splint.

Description

[0001] LUP01-134710PC

[0002] A DENTAL SPLINT AND METHOD OF MANUFACTURE FIELD OF THE INVENTION

[0003] This invention relates to robotically assisted or executed dentistry. For example, application of veneers and insertion of dental implants.

[0004] BACKGROUND

[0005] In everyday life, dental and medical problems are unfortunately commonplace. And if patients cannot receive appropriate treatment in time, these dental and medical problems can be extremely serious and painful, affecting their quality of life and health. In order to treat patients more quickly, there are increasing plans to use robots to assist practitioners in carrying out dental or medical procedures. Indeed, thanks to their controllable movements, robots can not only improve the efficiency of dental or medical procedures, but also the efficiency of treatment by avoiding or limiting human errors.

[0006] The use of robots in performing dental procedures has also become increasingly viable in recent decades due to advances in both robot technology and material science for dentistry. The use of robots in such procedures relies on providing a stable reference frame within which the robot operates. Existing systems often comprise attaching markers for this reference frame which are fixed relative to the subject in some way. There are many existing methods for determining these reference points for facilitating robot control. However, it can often be difficult to determine precise reference points relative to a subject’s body, especially if the subject is prone to moving. Similarly, maintaining the same reference frame across multiple appointments can be challenging due to the removal and re-attachment of such reference points.A particular field in which consistent and stable reference points are important is dentistry and other facial procedures. For example, such procedures may comprise, but are not limited to, attaching veneers, crowns, or implants, but also procedures such as orthodontic treatment, maxillofacial surgery, and facial surgery in general.

[0007] It is therefore desirable to develop an apparatus for providing stable and consistent reference points for robot assisted dental and facial procedures.

[0008] SUMMARY OF THE INVENTION

[0009] According to one aspect there is provided a dental splint for providing a positional reference with respect to a specific dentition of a subject, the splint comprising: a frame having a first clamping element and a second clamping element movable with respect to the first clamping element to mechanically grip a first tooth of the subject; and a first extension arm rigidly attached to the frame and extending from the frame for supporting a reference unit at a location outside the oral cavity of the subject when the frame is gripping the first tooth.

[0010] In an embodiment, the first clamping element may be integral with the second clamping element, and the first and second clamping elements may be flexibly interconnected such that the first and second clamping elements can be urged towards each other to grip the first tooth.

[0011] In an embodiment, the splint may comprise a locking piece sized to be engageable against the first and second clamping elements to urge the first and second clamping elements into contact with the first tooth.

[0012] In an embodiment, the locking piece may define a channel having side walls that can be engaged against the first and second clamping elements to urge the first and second clamping elements into contact with the first tooth.In an embodiment, the locking piece may be configured to releasably latch to the first and second clamping elements for holding it in engagement with the first and second clamping elements.

[0013] In an embodiment, the locking piece may be non-integral with the clamping elements.

[0014] In an embodiment, the locking piece may comprise a shoulder configured to engage a post located elsewhere on the dental splint for retaining the locking piece on the dental splint when not latched to the first and second clamping elements.

[0015] In an embodiment, the frame may have a third clamping element and a fourth clamping element movable with respect to the third clamping element to mechanically grip a second tooth of the subject, the second tooth being on the opposite quadrant of the same jaw to the first tooth.

[0016] In an embodiment, the splint may comprise a second locking piece sized to be engageable against the third and fourth clamping elements to urge the third and fourth clamping elements into contact with the second tooth.

[0017] In an embodiment, the first extension arm may be attached to the frame adjacent the first and second clamping elements and the splint may comprise a second extension arm for supporting the reference unit at a location outside the oral cavity of the subject when the frame is gripping the second tooth, the second extension arm being rigidly attached to the frame adjacent the third and fourth clamping elements.

[0018] In an embodiment, one of the first and second clamping elements may have a leading end and a trailing end, the trailing end being cupped so as to engage the occlusal surface of the first tooth and thereby limit insertion of the first tooth between the first and second clamping elements; one of the third and fourth clamping elements may have a further leading end and a further trailing end, the further trailing end being cupped so as to engage the occlusal surface of the second tooth and thereby limit insertion of the second tooth between the third and fourth clamping elements; theleading end and the further leading end may lie in a common planar zone; and the frame may comprise a bridge extending between (i) the first and second and (ii) the third and fourth clamping elements, the bridge being located no closer to the cupped regions of the first to fourth clamping elements than the common planar zone.

[0019] In an embodiment, the or each extension arm may carry a structure for releasably receiving the reference unit.

[0020] In an embodiment, the or each extension arm may carry the reference unit.

[0021] In an embodiment, the reference unit may be an optical reference unit comprising a plurality of optical reference sites.

[0022] In an embodiment, each optical reference site may comprise a recess for releasably receiving a reflector and a key surface shaped for fixing the position of the reflector relative to the frame.

[0023] In an embodiment, the optical reference unit may have at least three optical reference sites, the optical reference sites being located so as to be coplanar and not all collinear.

[0024] In an embodiment, the reference unit may be an inertial reference unit or a magnetic reference unit.

[0025] In an embodiment, the splint may be arranged so that when the first tooth or the second tooth is a molar or premolar of the subject, the splint does not occlude the facial surfaces of the incisors of the same dental arch as the first tooth.

[0026] In an embodiment, the first and second clamping elements, and the third and fourth clamping elements may be shaped to match the contours of molars and / or premolars of a subject.In an embodiment, the first tooth or the second tooth may be of a first dental arch of the subject and the splint comprises a jaw plate for engaging the other dental arch of the subject, the jaw plate being releasably attachable to the frame in a position to engage the other dental arch and thereby restrict motion of the jaws of the subject towards each other.

[0027] In an embodiment, either the frame or the jaw plate may comprise a tongue restraint for restraining the tongue of the subject.

[0028] In an embodiment, either the frame or the jaw plate may comprise a formation for holding a suction tube in the subject’s oral cavity.

[0029] In an embodiment, the or each extension arm may comprise a stabilising branch, each stabilising branch disposed between: the first extension arm and the first / second clamping element; and / or the second extension arm and the third / fourth clamping element.

[0030] According to another aspect there is provided a method for providing a positional reference with respect to dentition of a subject, the method comprising: causing a dental splint as claimed in any preceding claim to grip a tooth of the subject; and imaging a reference unit carried by the or each extension arm of the dental splint.

[0031] In an embodiment, the method may comprise: forming the first and second clamping elements to match the contours of the first tooth of the subject or forming the third and fourth clamping elements to match the contours of the second tooth of the subject.

[0032] In an embodiment, the method may comprise: scanning the first tooth or second tooth so as to form a set of three-dimensional data representing the shape of the first tooth or second tooth; and forming the first and second clamping elements or the third and fourth clamping elements in dependence on the set of three-dimensional data.In an embodiment, the method may comprise forming the first and second clamping elements or the third and fourth clamping element by additive manufacturing.

[0033] According to another aspect there is provided a dental splint comprising: an arcuate jaw clamp extending around an arc of greater than 120 degrees and having a first recess at one end thereof and a second recess at the other end thereof, each recess having at least one side wall for contacting a lateral surface of at least one tooth of a subject and a basal surface extending transversely to the side wall for contacting occlusal surfaces of at least one tooth in the recess for limiting the insertion of at least said tooth into the recess in a first direction; wherein both the basal surfaces lie on a common basal plane and the jaw clamp has a bridge extending between the first recess and the second recess, a central region of the bridge extending, on the convex side of the arc, no further in a direction opposite to the first direction than the basal plane.

[0034] In an embodiment, each recess may comprise a first clamping element and a second clamping element, the clamping elements of each recess being moveable with respect to each other to mechanically grip a tooth of the subject located in the respective recess.

[0035] In an embodiment, the splint may comprise at least one extension arm rigidly attached to the arcuate jaw clamp and extending from the arcuate jaw clamp for supporting a reference unit at a location outside the oral cavity of the subject when the arcuate jaw clamp is engaged with one or more teeth in the recesses.

[0036] In an embodiment, the extension arm may carry a structure for releasably receiving the reference unit.

[0037] In an embodiment, the extension arm may carry the reference unit.

[0038] According to another aspect there is provided a dental splint comprising: an arcuate jaw clamp extending around an arc of greater than 120 degrees and having a firstrecess at one end thereof for receiving a first molar or premolar of a subject, and a second recess at the other end thereof for receiving a second molar or premolar of the subject, the first and second molars or premolars being in the same dental arch but different quadrants thereof; the jaw clamp comprising a bridge extending between the first recess and the second recess and shaped such that when the first recess receives the first molar or premolar and the second recess receives the second molar or premolar, the bridge does not occlude the facial surfaces of the incisors of the said dental arch.

[0039] In an embodiment, the splint may comprise at least one extension arm rigidly attached to the arcuate jaw clamp and extending from the arcuate jaw clamp for supporting a reference unit at a location outside the oral cavity of the subject when the arcuate jaw clamp is engaged with one or more teeth in the recesses.

[0040] In an embodiment, the extension arm may carry a structure for releasably receiving the reference unit.

[0041] In an embodiment, the extension arm may carry the reference unit.

[0042] In an embodiment, the bridge may be shaped to fit within the curve of the roof of the subject’s mouth and / or within the dental arch.

[0043] In an embodiment, the at least one extension arm may be attached to the arcuate jaw clamp at a proximal end by a plurality of branches arranged to dampen vibrations between the arcuate jaw clamp and the extension arm.

[0044] In an embodiment, the plurality of branches may comprise a first and a second branch which extend from the proximal end of the at least one extension arm and are fixedly attached to the jaw clamp adjacent to the first and second recesses respectively.

[0045] In an embodiment, the plurality of branches may comprise a third branch which is fixedly attached to the bridge and splits into a fourth and a fifth branch, where each ofthe fourth and fifth branch extend from the distal end of the third branch towards the proximal end of the at least one extension arm.

[0046] In an embodiment, the plurality of branches may comprise a sixth branch which extends from the proximal end of the at least one extension arm and terminates at the distal end of the third branch.

[0047] In an embodiment, the dental splint may comprise a brace positioned between the first branch and the second branch and orientated perpendicularly to the at least one extension arm.

[0048] In an embodiment, the at least one extension arm may be forked at a distal end for supporting the reference unit.

[0049] In an embodiment, the dental splint may comprise two further extension arms, where each further extension arm is fixed at its distal end to a distal portion of the at least one extension arm supporting the reference unit and at a proximal end to a curved rail, the curved rail rigidly attached at its ends to the arcuate jaw clamp at points adjacent to the first and second recesses.

[0050] In an embodiment, the dental splint may comprise a first pair of support arms, wherein each support arm extends from the structure for releasably receiving the reference unit and terminates at a respective elbow of one of the two further extension arms.

[0051] In an embodiment, the dental splint may comprise a second pair of support arms, where each of the second pair of support arms extend from the at least one extension arm and terminate on a respective one of the two further extension arms.

[0052] In an embodiment, the arcuate jaw clamp may be a maxillary arcuate jaw clamp comprising: a protrusion extending from the proximal end of the at least one extension arm in a direction opposite to and away from the bridge, and at least one first wedgeprotruding from an occlusal surface adjacent to the first recess and / or the second recess.

[0053] In an embodiment, a focused edge of the first wedge may be orientated parallel to the bridge of the arcuate jaw clamp.

[0054] In an embodiment, the dental splint may comprise a mandibular portion extending over the dental arch of the subject's mandible and comprising: a bridge extending between the two quadrants of the mandibular dental arch, the bridge comprising a niche shaped to receive the protrusion and configured to prevent lateral excursion of the mandible; and at least one second wedge protruding from a molar occlusal surface of the mandibular portion, the at least one second wedge being shaped to receive and abut the at least one first wedge protruding from the occlusal surface adjacent to the first recess and / or the second recess of the maxillary arcuate jaw clamp to prevent protrusion of the mandible.

[0055] In an embodiment, the mandibular portion may comprise a suction cannula extending between two ends of the mandibular dental arch, the suction cannula comprising: at least one outlet channel protruding perpendicular to the suction cannula and configured to terminate outside of the subject's mouth; and a plurality of openings towards at least one end of the suction cannula located adjacent to at least one of the two ends of the mandibular dental arch.

[0056] In an embodiment, the channel may be configured to be connected to an aspiration system.

[0057] In an embodiment, the plurality of openings may be located on the end and on one or more sides of the at least one end of the suction cannula.

[0058] In an embodiment, the niche may comprise a trench which runs perpendicular to the bridge of the mandibular portion.BRIEF DESCRIPTION OF THE FIGURES

[0059] The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings:

[0060] Figure 1 shows an example dental splint.

[0061] Figure 2 shows an example dental splint viewed from above.

[0062] Figure 3 shows an example dental splint viewed from the back.

[0063] Figure 4 shows a perspective view of an example dental splint.

[0064] Figure 5 shows a perspective view and a side view of an example locking piece.

[0065] Figure 6 shows a perspective view of an example locking piece engaged with clamping elements.

[0066] Figure 7 shows a plan view of an example jaw plate for engaging the other dental arch of the subject.

[0067] Figure 8 shows a perspective view of an example dental splint.

[0068] Figure 9 shows an example dental splint.

[0069] Figure 10 shows a perspective view of an example jaw plate.

[0070] Figure 11 shows a perspective view from the side of an example jaw plate comprising an end region / cross-section near a tongue restraint.

[0071] Figure 12 shows a front view of an example jaw plate.Figure 13 shows an example dental splint.

[0072] Figure 14 shows a rear view of an example dental splint.

[0073] Figure 15 shows a perspective view of an example dental splint.

[0074] Figure 16 shows a perspective view of an example embodiment of a dental splint viewed from the front.

[0075] Figure 17 shows a perspective view of an example embodiment of a dental splint viewed from below.

[0076] Figure 18 shows a perspective view of an example dental splint.

[0077] Figure 19 shows a front view of an example dental splint.

[0078] Figure 20 a side view of an example splint for engaging one half of a dental arch.

[0079] Figure 21 shows a rear view of an example dental splint.

[0080] Figure 22 shows a perspective view of an example embodiment of the dental splint.

[0081] Figure 23 shows a top view of an example mandibular portion of the dental splint.

[0082] Figure 24 shows a perspective view of an example mandibular portion of the dental splint.

[0083] Figure 25 shows a side perspective view of an example dental splint comprising a maxillary arcuate dental splint with mandibular portion.Figure 26 shows a front perspective view of an example dental splint comprising a maxillary arcuate jaw clamp and mandibular portion.

[0084] Figure 27 shows a side perspective view of an example dental splint comprising a maxillary arcuate jaw clamp and mandibular portion.

[0085] DETAILED DESCRIPTION OF THE INVENTION

[0086] There is provided herein a dental splint for providing a positional reference with respect to dentition of a subject. Such a splint may be used in dental procedures which make use of a robot controlled or manipulated dentistry tool. For example, tools for milling the surface of teeth during a process of applying veneers or other cosmetic and / or functional dental prostheses. Non-limiting examples other than veneers include crowns and implants.

[0087] The proposed dental splint could be applied to other types of treatment, such as crown or implant, but also such as orthodontic treatment, maxillofacial surgery, and facial surgery in general. In particular, the system enables reference markers to be connected to a subject in a stable way, since they are connected to a “hard” part of the subject's anatomy, the teeth, without being invasive. That is, the reference markers in this way are connected indirectly to the jawbone, for example, or to the skull bone via the teeth.

[0088] As mentioned above, applying veneers is just one example of a dental procedure in which such a dental splint may be used. During a conventional treatment process, there is typically a visit which consists of milling the patient’s teeth. There is then a further visit which consists of fitting the dental prostheses that will have been made since the previous visit where the milling took place. A robotic tool may be used to provide the milling. In order to achieve the described process, the spatial position and orientation of the tooth or teeth to be milled needs to be precisely known in relation to the spatial position and orientation of the robotic tool. This allows a controller of the robot to mill the teeth as required for the veneers.The spatial alignment (in position and orientation) may be achieved by use of a detecting system directed towards the subject and one or more markers fixed relative to the subject’s teeth. There may also be markers fixed to the robot. The detecting system can then be used to detect the markers and use them as reference points for knowing the relative position of the subject’s teeth to the tool. A processor can detect the markers in an image captured by the detecting system. The processor can estimate the relative position and orientation of the teeth and the robot in dependence on the relative positions of the markers in an image captured by the detecting system. The teeth may be provided with multiple markers, which may be arranged to be non-collinear. This can assist in detecting the orientation of the teeth. The robot may be provided with multiple markers, which may be arranged to be non-collinear. This can assist in detecting the orientation of the robot. In each case the distance between the markers as observed by the detecting system can be used to estimate the direction and distance of the teeth / robot with respect to the detecting system. The detecting system may comprise a stereoscopic camera which can detect optical markers. Alternatively, the dental splint could be used alongside another optical tracking system using a laser as the detection system rather than a camera. In another alternative, the dental splint could be used alongside an inertial tracking system, in which case the detected inertial information may be provided to the robot or an intermediate control entity. In another alternative, the dental splint could be used alongside a magnetic tracking system, in which case the dental splint could be linked to an arm attached to the robot.

[0089] Existing ways of fixing one or more optical markers to the subject comprise removably fixing one or more markers to the subject’s other teeth, i.e. those which are not undergoing work. For example, typically a stick-like item having an optical marker on one end may be fixed across the face of one or more other teeth of the subject, e.g. the molars, with the optical marker end orientated towards the front of the mouth. The object and optical marker may therefore be temporarily attached with adhesive or cement to the subject’s teeth so that the marker is fixed with respect to the subject’s teeth. However, this is not always a secure bond. The bond may have some elasticitywhich permits the marker to move relative to the teeth. Consequently, the optical marker may not be as positionally accurate as needed and may be accidentally dislodged.

[0090] It has been recognised that a more stable, secure, and positionally accurate way of determining the location of a subject’s teeth relative to a computer-controlled tool is needed.

[0091] There is provided herein a dental splint for providing a positional reference with respect to dentition of a subject. Accordingly, the splint may be rigidly fixed in position relative to the subject’s teeth and provide a means for securing one or more reference points.

[0092] The proposed dental splint will now be described in reference to the example embodiment shown in the figures. It should be understood that the dental splint is not limited to the specific embodiment shown in any one of the figures. It should also be understood that when implemented, different features presented alongside the content of different figures may be combined in any combination as defined by the claims.

[0093] The proposed system is designed to treat the teeth of the maxilla and mandible. In this context, the frame can be engaged with one or more teeth of the upper jaw if the treatment is performed on one or more teeth of this jaw, or the frame can be engaged with one or more teeth of the lower jaw if the treatment is performed on one or more teeth of this jaw. That is, the frame is engaged with the jaw being treated. Thus, in a third implementation, the splint may be engaged simultaneously with the dental arch of the upper jaw and the dental arch of the lower jaw.

[0094] Figure 1 shows an example embodiment of the dental splint 100. The splint 100 comprises a frame 102 having a first clamping element 104 and a second clamping element 106. The second clamping element 106 is movable with respect to the first clamping element 104 to mechanically grip a first tooth of the subject. That is, the frame provides two halves of a gripping portion of the splint which can engage one or more neighbouring teeth of the subject. The frame 102, as shown in figure 1, isconfigured to engage with the upper dental arch of the subject. It should be understood that the first and second clamping elements need only engage one side of the dental arch. A dental arch is the teeth of the upper jaw or the teeth of the lower jaw.

[0095] The splint 100 also comprises a first extension arm 108 rigidly attached to the frame 102 and extending from the frame 102 for supporting a reference unit at a location outside the oral cavity of the subject when the frame is gripping the first tooth. The extension arm may be rigidly attached to the frame at one end and extend in a direction perpendicular to the plane of the biting surface of the upper dental arch. The extension arm may be shaped to exit the oral cavity of the subject and clear the subject’s lower jaw. The reference unit may be any structure which may be detected and used to provide a reference point for relative positioning of the splint, and therefore the teeth of the subject, relative to a robotically manipulated dental tool.

[0096] In an embodiment the splint structures described, such as the frame, may be implemented on both dental arches at once. Any reference herein to upward or downward directions relative to teeth etc. are made in reference to the example dental splint shown in the figures and are not intended to limit the use of the splint to any single dental arch / jaw configuration. Further, description of the orientation of the dental splint is based on the example dental splint shown in the figures orientated while in use and looking at the face of the subject. Though it should be understood that when in use the example dental splint may be fixed to a subject while the subject is in a reclining or supine position.

[0097] Figure 2 shows an example embodiment of the splint 100 viewed from above. The frame 102 is located at the top of the splint 100 and the extension arm 108 extends towards the bottom of the splint 100 (into the plane of the page). The first clamping element 104 may be integral with the second clamping element 106. That is, the first and second clamping elements may be formed as different parts of a single structure.

[0098] The first and second clamping elements may be flexibly interconnected such that the first and second clamping elements can be urged towards each other to grip the firsttooth. Figure 2 shows how the first and second clamping elements may be interconnected along a portion of the frame below the biting surface of the subject’s upper teeth. This join 210 may comprise a single connection or multiple smaller connections. The number of connections between the first and second clamping element may depend on the desired flexibility. The thickness of the connection(s) between the first and second clamping element may depend on the desired flexibility. The length of the connection(s) between the first and second clamping element may depend on the desired flexibility.

[0099] The frame 102 may have a third clamping element 204 and a fourth clamping element 206. The fourth clamping element 206 may be movable with respect to the third clamping element 204 to mechanically grip a second tooth of the subject. The second tooth may be located on the opposite quadrant of the same jaw to the first tooth.

[0100] The first extension arm 108 may be attached to the frame adjacent the first clamping element 104 and the second clamping element 106 and the splint 100 may comprise a second extension arm 208 for supporting the reference unit at a location outside the oral cavity of the subject when the frame is gripping the second tooth, the second extension arm being rigidly attached to the frame adjacent the third clamping element 204 and the fourth clamping element 206. That is, where there are two extension arms, they may each be attached to the frame 102 next to one of the two sets of clamping elements as shown in figure 2.

[0101] Figure 3 shows an example embodiment of the dental splint 100 as viewed from the back. In this figure the dental splint 100 is orientated such that the subject’s molars are in front of the incisors and the extension arm extends downwards and away from the subject’s lower jaw (into the plane of the page). The extension arm may curve backwards around the lower jaw towards the subject. The extension arm may terminate in a structure 320 for supporting a reference unit.

[0102] There may be a gap or channel or slot defined between the first and second clamping elements and between the third and fourth clamping elements. Figure 3 shows thisslot 302, which allows for the third and fourth clamping elements to be urged together to grip around the one or more teeth of the subject.

[0103] One of the first and second clamping elements 104,106 may have a leading end 312 and a trailing end 314. The trailing end 314 may be cupped so as to engage the occlusal surface of the first tooth and thereby limit insertion of the first tooth between the first and second clamping elements. That is, the edge located towards the biting surface of the tooth may be cupped. The cupped portions may surround and hold a portion of the biting surface of at least the first tooth and prevent it from passing between the griping surfaces of the clamping elements.

[0104] One of the third and fourth clamping elements 204, 206 may have a further leading end 316 and a further trailing end 318. The further trailing end 318 may be cupped so as to engage the occlusal surface of the second tooth and thereby limit insertion of the second tooth between the third and fourth clamping elements. Similarly, the edge of the third and fourth clamping elements located towards the biting surface of the tooth may be cupped. The cupped portion may surround and hold the biting surface of at least the second tooth and prevent it from passing between the griping surfaces of the clamping elements.

[0105] The leading end and the further leading end may lie in a common planar zone. That is, the top edges of the clamping elements closest to the gums of the dental arch lie in a zone around a common plane. The common planar zone is therefore approximately parallel to the plane of the dental arch.

[0106] The frame may comprise a bridge 310 extending between the first and second, and the third and fourth clamping elements. The bridge 310 therefore joins together the two pairs of clamping elements located at the ends of the dental arch. The bridge may be located no closer to the cupped regions of the first to fourth clamping elements than the common planar zone. That is, for example, when considering the dental clamp positioned on an upper jaw, the bridge may be located above the edges of the clamping elements inside the dental arch. This may coincide with the inside gum lineof the molars and premolars. For example, the bridge may be shaped to cover the flat portion of the hard palate and / or the arched part of the hard palate behind the front incisors. As such, it may span part of the roof of the subject’s mouth. Alternatively, for implementing the dental splint for the lower jaw, it may sit under the subject’s tongue.

[0107] Figure 4 shows a perspective view of the dental splint. The splint is illustrated as viewed from below at an approximate 45-degree angle towards left from centre. The frame is towards the background while the structure 320 for supporting the reference unit is in the foreground. In this example, the two are connected by two extensions arms. The or each extension arm may carry a receptacle 402 for releasably receiving the reference unit. In this example, the receptacle 402 is illustrated as a spherical ended protrusion which is angled such that a reference unit may be held behind it. It should be understood that the receptacle could take many forms to provide this function, for example, a tab or hook. The tab or hook could be shaped to fit a corresponding notch or groove in the reference unit. The receptacle could instead be a notch or groove for receiving a tab or hook on the reference unit.

[0108] The receptacle 402 may form part of the structure 320 for receiving and securing the reference unit. For example, in figure 4 the structure 320 is a triangular structure or Y shaped yoke at the ends of a pair of extension arms. The receptacle 402 may be located on the or an extension arm which then may be configured to continue and terminate in a further receptacle or a clip 406. Where there are a plurality of extension arms, the extension arms may meet at the end and a single further receptacle or a clip 406 may be located in the area of intersection. Therefore, the or each extension arm may carry the reference unit.

[0109] The reference unit may have a plurality of reference sites. That is, for example, in the case of an optical reference unit, the optical reference unit may comprise multiple sites comprising individually optically detectable points which may be used together to provide a reference frame for relative positioning of the splint. Each optical reference site may comprise a recess for releasably receiving a reflector and a key surface shaped for fixing the position of the reflector relative to the splint frame. The referenceunit may have at least three optical reference sites, the optical reference sites being located so as to be coplanar and not all collinear.

[0110] The splint may be arranged so that when the first tooth or the second tooth is a molar or premolar of the subject, the splint does not occlude the facial surfaces of the incisors of the same dental arch as the first tooth. A portion of the frame may be shaped to fit the inside concaved surface of the dental arch. The portion of the frame shaped to fit the inside concaved surface of the subject's dental arch includes an apex 404. The apex 404 is shaped to sit behind the front teeth or against part of the palate of the subject. This way the surfaces of the front teeth are not obstructed and may be accessed for dental procedures. The first and second clamping elements, and the third and fourth clamping elements may be shaped to match the contours of molars and / or premolars of the subject. This allows for a precise and well-defined orientation of the splint. As the gripping elements match the shape of the teeth they are gripping, there is little to no sliding or shifting of the gripping elements possible across the surface of the teeth once gripped.

[0111] The splint 100 may comprise a locking piece 500 sized to be engageable against the first and second clamping elements 104 and 106 to urge the first and second clamping elements into contact with the first tooth. Figure 5a shows a perspective view of an example locking piece 500. The locking piece may be sized to fit over the first and second clamping elements and push them together. The locking piece may define a channel having side walls 502a, 502b that can be engaged against the first and second clamping elements to urge the first and second clamping elements into contact with the first tooth. That is, the locking piece 500 may be U-shaped and configured to slide over the first and second clamping elements so as to force them together to grip the first tooth. The locking piece may be configured to releasably latch to the first and second clamping elements for holding it in engagement with the first and second clamping elements. The locking piece may be non-integral with the clamping elements. That is, the locking piece may be a separate item from the clamping elements it is configured to engage.The splint may comprise a second locking piece sized to be engageable against the third and fourth clamping elements to urge the third and fourth clamping elements into contact with the second tooth. The second locking piece may be identical to the first locking piece. The second locking piece may be a mirror image of the first locking piece. That is, the second locking piece may have the same structural features as the first locking piece, but these features may be arranged to engage the opposite side of the same dental arch, i.e. the third and fourth clamping elements, thus requiring those structural features to be reversed or rotated 180 degrees.

[0112] The side walls 502a and 502b may not be the same size or shape as each other. For example, a first side wall 502a may be smaller than a second side wall 502b. The internal surfaces of the side walls, the surfaces within the channel, may be shaped to cooperate with the outside surfaces of the first and second clamping element or the third and fourth clamping element respectively.

[0113] Figure 5b shows a side view of the locking piece 500. Side wall 502a may be shorter than side wall 502b. This may be because side wall 502a lies inside the dental arch of the subject, whereas side wall 502b lies outside the dental arch of the subject. Therefore, the second side wall 502b has a greater amount of space over the gums which remains in the same plane as the facial surface of the teeth / tooth being gripped. However, the first side wall 502a may have less space due to the palate of the subject, which may extend at an angle towards the roof of the mouth and outward from approximately the base of the teeth / tooth being gripped. It should be understood that should the dental splint be configured for engaging a different part of or whole dental arch, the walls of the locking piece may be sized accordingly to account for available depth and access to the necessary teeth / tooth.

[0114] The locking piece may be engaged against the first and second clamping elements in two configurations.

[0115] In a first configuration, the locking piece is in an unlocked or relaxed configuration. In the unlocked or relaxed configuration, the locking piece is loosely engaged against theside walls of the first and second clamping elements or against the side walls of the third and fourth elements. A respective locking piece is loosely engaged with each pair of clamping elements.

[0116] In a second configuration, the locking piece is in a locked or tight configuration. In the locked or tight configuration, the locking piece is latched against the side walls of the first and second clamping elements or against the side walls of the third and fourth clamping elements. A respective locking piece is latched to each pair of clamping elements.

[0117] The locking piece may comprise a shoulder 504.

[0118] In the unlocked or relaxed configuration, the shoulder 504 may rest on a post or complementary shaped protrusion 602 as shown in Figure 6a. In this way, in the unlocked or relaxed configuration the locking piece may be retained by the corresponding post (or complementary shaped protrusion). The corresponding post (or protrusion) may be located on another part of the dental splint, for example the complementary post (or protrusion) may be located on an extension arm as shown in Figure 6a, in Figure 6b, and in Figure 13. The post (or protrusion) may retain the locking piece on the dental splint during placement of the dental splint on the subject's jaw.

[0119] In the locked or tight configuration, the shoulder 504 and the post (or protrusion) 602 are no longer in contact, as shown in Figure 6b.

[0120] When the dental splint is placed on the subject’s jaw, the locking piece can be slid, over the side walls of the first and second clamping elements towards the leading end 312 or over the side walls of the third and fourth clamping elements towards the further leading end 316, to move from the unlocked configuration to the locked configuration. In the locked configuration, the side walls of the first and second clamping elements clamp the first tooth or the side walls of the third and fourth clamping elements clampthe second tooth. In the locked configuration, the dental splint is positioned in a fixed and stable manner on the subject's jaw.

[0121] When the dental splint is removed from the subject’s jaw, the locking piece can be slid, over the side walls of the first and second clamping elements or over the side walls of the third and fourth clamping elements, towards the post (or protrusion) 602 until the shoulder 504 of the locking piece rests on the post (or protrusion) 602, to move from the locked configuration to the unlocked configuration. In the unlocked configuration, the side walls of the first and second clamping elements release the first tooth or the side walls of the third and fourth clamping elements release the second tooth. In the unlocked configuration, the dental splint is loosely positioned on the subject's jaw.

[0122] The locking piece may comprise a notch or ridge 506 for engaging a corresponding ridge or notch respectively on the first or second clamping element. In this way the locking piece may be configured to releasably latch to the first and second clamping elements for holding it in engagement with the first and second clamping elements. This may be achieved by any number of similarly shaped cooperating portions of the clamping elements and locking piece for releasably securing them together. Additionally, or alternatively, these cooperating portions, comprising for example a notch and ridge, provide haptic feedback while fitting the dental splint. That is, the movement of the corresponding notch and ridge over each other can provide haptic feedback to the person assembling the dental splint to indicate that the locking piece is sufficiently covering the clamping elements. As such, the haptic feedback may indicate that the locking piece does not need to be pushed any further over the clamping elements or that the locking piece has reached a minimum amount of overlap with the clamping elements. In this way in can be assured that the locking piece will not accidentally slip off of the clamping elements.

[0123] The proposed system is specifically designed to be easy to fit to and remove from the subject's jaw. In particular, the splint is designed such that it is not necessary to use an element independent of the splint in order to be able to install it in the subject's mouth. That is, the elements constituting the dental splint as such are alone sufficientfor enabling the fitting. Similarly, it is not intended to be necessary to use a tool to remove the dental splint from the subject's mouth, although mechanisms to facilitate removal are proposed for added safety and convenience.

[0124] The locking piece may additionally comprise a hole 508. The hole 508 is provided so that a small tool independent of the dental splint may be inserted to facilitate removal of the locking piece from the splint and the subject's mouth. Although, the locking piece is designed to be easily removed, the tool may be used in the hole 508 as a last resort to ensure the splint can be removed in a safe and controlled manner.

[0125] Figure 7 shows a plan view of an example jaw plate 700 for engaging the other dental arch of the subject which is not being treated. The jaw plate 700 is shown from above when configured to engage the lower dental arch of the subject such that the relief of the impressions of the occlusal surfaces can be seen. It should be understood that the relief impressions may not always be visible in this manner as the opposite side of the jaw plate to the teeth of the subject may be moulded to any desired shape. That is, the first tooth or the second tooth may be of a first dental arch of the subject and the splint may comprise a jaw plate for engaging the other dental arch of the subject.

[0126] The jaw plate may be releasably attachable to the frame in a position to engage the other dental arch and thereby restrict motion of the jaws of the subject towards each other. For example, the jaw plate 700 may comprise one or more formations 702a and 702b for engaging one or more corresponding portions of the frame 102 and preventing the two parts from moving closer together. An example of a corresponding portion of the frame is shown in figure 3, whereby an elongate protrusion or a flat blade-like structure 322 extends from at least one extension arm to engage the formation 702.

[0127] Further, either the frame 102 or the jaw plate 700 may comprise a tongue restraint 704a and / or 704b for restraining the tongue of the subject. Two examples of such tongue restraints are shown in figure 7. The one or more restraints may also act as a support to provide stability to the structure of the jaw plate 700.Additionally, either the frame 102 or the jaw plate 700 may comprise a formation 706 for holding a suction tube in the subject’s oral cavity. This allows for a suction tube to be positioned for removing excess saliva of the subject throughout the dental procedure without always needing to be held by the dentist or assistant. The suction tube may also be easily repositioned with regard to location inside the subject’s mouth and its angle. A plurality of formations 706a and 706b may provide different angles for the suction tube so as to remove the saliva in the most efficient and comfortable position.

[0128] The jaw plate 700 as shown in figure 7 engages the whole of the dental arch not being worked on. However, in some embodiments the jaw plate may only engage a portion of the opposite dental arch. For example, the jaw plate may only engage one or more molars towards the back of the opposite dental arch. The jaw plate in this configuration may take the shape of a wedge, which is deeper toward the front of the subject’s mouth than it is towards the back of the subject’s mouth. In this way the shape of the jaw plate may mirror the angle between the two dental arches and set a minimum angle at which they can be spaced apart. This enables the subject’s mouth to remain at this open angle without the subject being required to hold this position.

[0129] Figure 8 shows a perspective view of an example dental splint 100 comprising the frame 102, extension arm(s) 108, 208 for supporting a reference unit, locking piece 500, and jaw plate 700 in an assembled configuration. In this example the jaw plate 700 engages the frame 102 between two pairs of corresponding formations 702 and flat blade-like structures (or elongate protrusions) 322.

[0130] As described above, on the outside of the molars there may be a clamping element or wall and on the inside of the molars there may be another clamping element or wall. Those walls may have a gap between them. The frame comprising the walls may be placed inside the subject’s mouth with the channel between those walls going over the molars and the base of the channel seated on the occlusal surfaces, top or bottom biting surfaces, of the molars. The locking pieces or clips, which comprise twoessentially U-shaped clips, may then be pushed over the two wing-like walls which forces the walls together to mechanically grip the teeth. That is, the locking pieces go over the outside of the wing-like walls and force them together into contact with the teeth. The locking pieces may be put in place by pushing them on. The locking pieces may clip into place. The locking pieces may be held in place by friction.

[0131] There may be two extension arms fixed to the frame and at the end of those there may be an interface for supporting a referent unit. The interface may allow for the reference unit to be clipped onto the splint. The reference unit may have some markers on it that a detecting system can be used to detect. The purpose of the one or more extension arms is to extend out of the mouth so that the reference unit may be located outside the mouth and away from where the robot is working. Therefore, the reference unit is not getting in the way of the robot.

[0132] When markers are optical markers, a camera can be used to image optical markers and there may be optical markers on both the robot and associated with the subject. Typically, in this way the optical reference unit is a plate with optical markers on it. The plate may be of any shape suitable for attaching one or more optical markers. In the example shown in figure 8, the optical reference unit is a plate sized to fit within the receptacles 402 and the further receptacle or clip 406. The plate may sit within the receptacles 402 and the further receptacle or clip 406 and sit flush against the surface of the structure 320 which may be a triangular structure or Y shaped yoke. By imaging the optical markers on the subject and the robot it is possible to determine the spatial relationship between the subject and the robot.

[0133] The jaw plate 700 is a removable piece that clips into the frame piece. Its purpose is to keep the subject's mouth open. It’s not necessary to know precisely where the untreated jaw is, all that is needed is to make sure that the subject is not able to bite the robot. Thus, the jaw plate may have one of more forked structures, which extend from it and towards the opposite jaw, and which slot over a corresponding fixture attached to the other jaw, e.g. on the frame or extension arm. The corresponding fixture may be as shown in figure 8, where the flat blade-like structure 322 is configuredto go into the fork-like structure 702 to form a jaw lock. The jaw plate may also comprise one or more C-shaped protrusions for clipping to a suction cannula.

[0134] The fork-like structures can clear the blade-like structures so long as the mouth of the subject is sufficiently open. Therefore, the jaw plate may be inserted after the main body of the dental splint is placed inside the subject’s mouth. Once the jaw plate is in place, the subject can then shut their mouth to a point and the fork-like structures will engage the blade-like structures. It is then not possible for the subject to shut their mouth any further. The blade-like structures and fork-like structures may also comprise shaped mating surfaces which resist movement apart once engaged together.

[0135] The dental splint may be made specific to an individual subject. Upon imaging the teeth of the subject, the frame, bridge, one or more pairs of clamping elements, and jaw plate may be formed to match the shape of the subject’s teeth and surrounding structures. For example, the clamping elements and the jaw plate may be made to fit the shape of the tooth or teeth of the upper or lower jaw. The bridge may match the contours of the hard palate of the subject.

[0136] The dental splint may be arranged so that during use it does not impede access to the teeth on which a procedure is to be performed.

[0137] The dental splint may be manufactured so as to match the dentition of a specific subject. The dental splint may be formed in dependence on a three-dimensional scan of the subject’s dentition. This can result in improved fit between the splint and the teeth of the subject, and hence reduced motion of the splint relative to the teeth of the subject when the splint is attached in place. The dental splint may be formed by additive manufacturing, e.g. three-dimensional printing, or by selective removal of material from a pre-formed blank.

[0138] There is provided a method for providing a positional reference with respect to dentition of a subject. The method comprises causing a dental splint as described herein to grip a tooth of the subject and detecting a reference unit carried by the oreach extension arm of the dental splint. The method may comprise forming the first and second clamping elements to match the contours of the first tooth of the subject or forming the third and fourth clamping elements to match the contours of the second tooth of the subject. That is, the method may comprise producing the clamping elements to be subject specific. This may comprise producing the subject specific parts of the splint based on 3D images of the subject’s teeth. For example, this may comprise forming moulds for parts of the splint or the splint itself. The processes may comprise casting, moulding, etching, or 3D printing.

[0139] Therefore, the method may comprise scanning the first tooth or second tooth so as to form a set of three-dimensional data representing the shape of the first tooth or second tooth. Then forming the first and second clamping elements or the third and fourth clamping elements in dependence on the set of three-dimensional data.

[0140] The method may comprise forming the first and second clamping elements or the third and fourth clamping element by additive manufacturing. Additive manufacturing is a process that creates a three-dimensional object from a digital model by adding material in layers. An example of additive manufacturing is 3D printing. Additive manufacturing can be used with lots of different materials such as polymers, metals, alloys, and ceramics. The additive manufacturing may be used to make the subject specific parts of the splint, or moulds for the subject specific parts.

[0141] Figure 9 shows an example of the dental splint 100 viewed from above. The dental splint may comprise one or more stopper arrangements 910 spanning the dental arch of the frame 102. In this example there are two stoppers 910a and 91 Ob. Each stopper may comprise two bumpers with a break or gap 902 in between. The stopper 910 may act as a pair of bumpers, where the ends of the bumpers either side of the gap 902 are configured to meet when pressure is applied to outside of the frame 102. Such pressure may be required to enable the frame to sit within the roof of the subject’s mouth. However, the frame may break if too much pressure is applied. Therefore, the stopper in the configuration of a pair of bumpers may limit the minimum distance between the pairs of clamping elements and prevent over-bending and breakage ofthe frame. Thus, the frame can flex while being put into place without snapping in the middle.

[0142] Figure 10 shows a perspective view of an example jaw plate 700.

[0143] Figure 11 shows a side on perspective view of an example jaw plate 700 including an end region / cross-section near the tongue restraint 704b. An example recessed shape of the formation 702a for engaging the frame 102 is also shown. The end region / cross-section illustrates that the jaw plate 700 may also be shaped to match the contours of the teeth of the subject. The jaw plate 700 may be shaped to match the contours of all of the teeth in a single dental arch of the subject. The jaw plate may be shaped to match the contours of molars and / or premolars of the subject. The jaw plate 700 may be shaped to match the contours of some or all of the teeth on the lower dental arch of the subject.

[0144] Figure 12 shows a front view of an example jaw plate 700. An example recessed shape of the formation 706b for holding a suction tube is also shown. As the suction tube is typically cylindrical in shape, the recess may be circular or annular with an arc section missing for accepting the suction tube.

[0145] Figure 13 shows an example dental splint 100. In this example the dental splint comprises one extension arm 108 which is rigidly fixed to a frame 102 configured to mechanically grip at least a first tooth of a subject and extending from the frame for supporting a reference unit. There is also shown an example of a post (or corresponding protrusion) 602 for engaging the shoulder 504 on the locking piece 500.

[0146] Figure 14 shows a rear view of an example dental splint 100 according to the above description.

[0147] Figure 15 shows a perspective view of an example dental splint 100.Figure 16 shows a perspective view of an example of another embodiment of a dental splint 1600 viewed from the front. There is provided a further dental splint 1600. The dental splint comprising an arcuate jaw clamp 1602 extending around an arc of greater than 120 degrees and having a first recess 1604 at one end thereof for receiving a first molar or premolar of a subject, and a second recess 1606 at the other end thereof for receiving a second molar or premolar of the subject. The first and second molars or premolars being in the same dental arch but different quadrants thereof. The jaw clamp comprising a bridge 1608 extending between the first recess 1604 and the second recess 1606 and shaped such that when the first recess receives the first molar or premolar and the second recess receives the second molar or premolar, the bridge 1608 does not occlude the facial surfaces of the incisors of the said dental arch. That is, the bridge is an integral part of the arcuate jaw clamp between the first and second recesses.

[0148] Each recess may comprise a first clamping element 1612 and a second clamping element 1614. The clamping elements of each recess may be moveable with respect to each other to mechanically grip a tooth of the subject located in the respective recess.

[0149] The splint may comprise at least one extension arm 1610 rigidly attached to the arcuate jaw clamp 1602 and extending from the arcuate jaw clamp for supporting a reference unit at a location outside the oral cavity of the subject when the arcuate jaw clamp is engaged with one or more teeth in the recesses.

[0150] The extension arm may carry a receptacle 1616 for releasably receiving the reference unit. The extension arm may carry the reference unit.

[0151] It should be understood that additional features as described above in relation to the embodiments show in figures 1 to 15 may also be implemented alongside the features described in reference to the embodiment show and described in reference figure 16.Figure 17 shows a perspective view of an example of another embodiment of a dental splint 1700 viewed from below. There is provided another embodiment of the dental splint. The dental splint 1700 comprises an arcuate jaw clamp 1702 extending around an arc of greater than 120 degrees and having a first recess 1704 at one end thereof and a second recess 1706 at the other end thereof. Each recess has at least one side wall for contacting a lateral surface of at least one tooth of a subject and a basal surface extending transversely to the side wall for contacting occlusal surfaces of at least one tooth in the recess for limiting the insertion of at least said tooth into the recess in a first direction. Both the basal surfaces lie on a common basal plane and the jaw clamp has a bridge 1712 extending between the first recess and the second recess, a central region of the bridge extending, on the convex side of the arc, no further in a direction opposite to the first direction than the basal plane.

[0152] Each recess may comprise a first clamping element 1708 and a second clamping element 1710, the clamping elements of each recess being moveable with respect to each other to mechanically grip a tooth of the subject located in the respective recess.

[0153] The splint may comprise at least one extension arm 1714 rigidly attached to the arcuate jaw clamp and extending from the arcuate jaw clamp for supporting a reference unit at a location outside the oral cavity of the subject when the arcuate jaw clamp is engaged with one or more teeth in the recesses.

[0154] The extension arm may carry a receptacle 1716 for releasably receiving the reference unit. The extension arm may carry the optical reference unit.

[0155] It should be understood that additional features as described above in relation to the embodiments show in figures 1 to 15 may also be implemented alongside the features described in reference to the embodiment show and described in reference figure 17.

[0156] Aspects of the above-described example embodiments of the proposed dental splint are also applicable to the embodiments described herein below. For example, featuresof the structure 320 for releasably supporting a reference unit are equally applicable to implementing the below-described embodiments of the dental splint.

[0157] Figure 18 shows a perspective view of an example dental splint. The example splint is configured to provide access to the surface of a small number of teeth, about 6, on at least the upper dental arch of the subject. The or each extension arm comprises a stabilising branch 1802, 1804. A stabilising branch 1802 may be disposed between the first extension arm 108 and the first and second clamping elements 104, 106. Another stabilising branch 1804 may be disposed between the second extension arm 208 and the third and fourth clamping elements 204, 206.

[0158] Figure 19 shows a front view of an example dental splint. The example dental splint shows two stabilising branches 1802, 1804, each fixed at one end to respective extension arms and at the other end to the outside of the first clamping element 104 or the third clamping element 204. The stabilising branches 1802, 1804 serve to reduce the respective motion between the frame 102 and the structure 320 for supporting the reference unit. The motion may be vibrations caused by the active use of a tool on the teeth of the subject wearing the dental splint. These vibrations can cause the tool to work on the teeth in an inaccurate manner, where the reference unit moves according to the vibrations, causing the relative motion of the tool to mimic the vibrations.

[0159] Figure 20 shows a side view of an example splint for engaging one half of a dental arch. In this configuration the splint comprises a single extension arm between the structure 320 and the frame 102.

[0160] Figure 21 shows a rear view of another example dental splint. In this example a plurality of branches are provided for minimising the vibrations between the frame 102 and the structure 320 for supporting the reference unit.

[0161] It should be understood that the figures 21 to 27 illustrate example implementations and arrangements of said branches which serve to minimise movements andvibrations and through the dental splint. The exact locations of such branches may vary depending on the specific configurations of the splint. For example, the materials used and method of construction of the splint. The configuration of the splint may include the anticipated tool configuration, for example, the motion direction and frequency of the moving parts of one or more tools to be used with the dental splint. The branches may be added and / or arranged to minimise resonant frequencies of the dental splint.

[0162] It should be understood that the illustrated branches are shown to provide example implementations. Any combination of branches located in suitable places within the structure of the dental splint for the purposes of minimising vibrations are disclosed herein and not limited according to those examples.

[0163] Vibrations may be caused by the working of a tool, but also by the motion of the subject, or a tool support, or any other apparatus used in the dental procedure capable of motion or causing vibrations. For example, a dental chair, which may provide a recline capability and one or more flexible elements as part of its construction.

[0164] The example dental splint of figure 21 shows a dental splint comprising an arcuate jaw clamp extending around an arc of greater than 120 degrees. The arcuate jaw clamp comprises a first recess 2102 at one end thereof for receiving a first molar or premolar of a subject, and a second recess 2104 at the other end thereof for receiving a second molar or premolar of the subject. The first and second molars or premolars are in the same dental arch but different quadrants thereof. The jaw clamp comprises a bridge 2106 extending between the first recess and the second recess and shaped such that when the first recess receives the first molar or premolar and the second recess receives the second molar or premolar, the bridge does not occlude the facial surfaces of the incisors of the said dental arch.

[0165] Said first and second recesses may be formed according to a specific dentition of the subject. That is, the jaw clamp may comprise a first and / or second recess which are moulded to the shape of the subject’s specific dentition. The moulded portion of thejaw clamp may extend at the first and / or second recesses towards the roof of the subject’s mouth before meeting the bridge 2106. That is, the moulded recesses and / or an extended portion of the jaw clamp may include and extend over the gumline towards the roof of the subject’s mouth. In an example embodiment, the moulded recess may include the base of the tooth but not extend over the gums, ending at the gumline. In many subjects the thickness of a tooth from facial surface to rear surface is narrower at the gum line, forming a natural gripping location for the moulded recess or extended jaw clamp portion. The moulded portion of the jaw clamp may not extend fully into the roof of the subject’s mouth. For example, as shown in figure 21 , the first and second recesses abut the bridge 2106. The bridge is shaped to fit within a curve of the roof of the subject’s mouth. That is, the bridge may be shaped to fit within said same dental arch of the subject. The bridge 2106 may be a flat plate or one or more rails which sit within the curve of the roof of the subject’s mouth but are not moulded to the shape of the hard palate. That is, the bridge may be configured to span the roof of the subject’s mouth between the first and second recesses.

[0166] There is therefore provided herein, a plurality of configurations for one or more branches connecting the at least one extension arm to the frame 102. The at least one extension arm 2108 may be attached to the arcuate jaw clamp 102 at a proximal end by a plurality of branches arranged to dampen vibrations between the arcuate jaw clamp and the extension arm 2108.

[0167] In the example implementation of the dental splint in figure 21, there is provided one extension arm 2108 positioned centrally to the frame 102 and the structure 320. The extension arm 2108 is fixed at the proximal end to the arcuate jaw clamp or frame 102 by a plurality of branches. The plurality of branches may comprise a first and a second branch 2110a, 2110b which extend from the proximal end of the at least one extension arm 2108 and are fixedly attached to the jaw clamp 102 adjacent to the first and second recesses 2102, 2104 respectively.

[0168] The plurality of branches may comprise a third branch 2112 which is fixedly attached to the bridge 2106. The third branch may split into a fourth and a fifth branch 2114a,2114b, where each of the fourth and fifth branch extend from the distal end of the third branch towards the proximal end of the at least one extension arm 2108. This arrangement of branches may help to resist compression of the proximal end of the extension arm 2108 towards the bridge 2106. The fourth and fifth branches 2114a, 2114b may help to stabilise and minimise lateral movement between the structure 320 and the bridge 2106 and / or frame 102 via the extension arm 2108 and the first and second branches 2110a, 2110b.

[0169] The dental splint may comprise a brace 2116 positioned between the first branch 2110a and the second branch 2110b and orientated perpendicularly to the at least one extension arm 2108. That is, the brace 2116 may be orientated such that it is longitudinally positioned perpendicularly to a plane which bisects the at least one extension arm 2108 along its length. The brace 2116 helps to minimise the flexion between the first and second branches 2110a, 2110b. The brace 2116 may also help to change the frequency of resonant vibrations in the dental splint.

[0170] The at least one extension arm 2108 may be forked at a distal end for supporting the reference unit. Accordingly, the distal end of the at least one extension arm 2108 may be fixedly attached to the structure 320 in two locations. The dimensions of the forked end of the extension arm may be proportioned so as to minimise vibrations and maximise rigidity of the dental splint.

[0171] Figure 22 shows a perspective view of the dental splint. The plurality of branches may comprise a sixth branch 2202 which extends from the proximal end of the at least one extension arm 2108 and terminates at the distal end of the third branch 2112. The sixth branch may further help to resist compression of the proximal end of the extension arm 2108 towards the bridge 2106. The sixth branch 2202 may also reduce the vibrations though the dental splint and / or change the frequency of resonant vibrations of the dental splint. It can be seen in figure 22 that the longitudinal axis of the sixth branch and the at least one extension arm 2108 may be aligned or co-linear. This relative orientation may provide rigidity to the dental splint. This arrangement mayalso facilitate manufacture by reducing the number of separate linear structures needed for the dental splint to be constructed.

[0172] The dental splint may comprise two further extension arms 2204a 2204b. Each further extension arm 2204a, 2204b may be fixed at its distal end to a distal portion of the at least one extension arm 2108 supporting the reference unit, and at a proximal end to a curved rail 2206. The curved rail 2206 may be rigidly attached at its ends to the arcuate jaw clamp 102 at points adjacent to the first and second recesses 2102, 2104. The distal portion of the at least one extension arm may comprise the two forked distal ends of the at least one extension arm, as illustrated in figures 21 and 22. It should be understood that the length of the forked ends, the shape of the forked ends, the distance the forked ends are apart at contact with the structure 320, and / or the proportion of the at least one extension arm that encompasses the forked end may each vary depending on the construction of the dental splint as a whole. That is, depending on the overall dimensions and ratios of parts of the dental splint, the forked ends of the at least one extension arm may be differently arranged in order to provide the maximum stability to the dental splint. For example, the arrangement of the distal portion and the forked end may be optimised to minimise vibrations of the dental splint when in place on a subject’s dentition and one or more tools are in use.

[0173] The dental splint may comprise a first pair of support arms 2208a, 2208b. Each support arm may extend from the structure 320 for supporting the reference unit and terminate at a respective elbow of one of the two further extension arms 2204a, 2204b. It should be understood that by the term elbow it is meant at a location on the further extension arm that is significantly bent. The bend may be located about halfway along the support arm. The elbow may be a location on the support arm which is bent to form an angle which is less than 150 degrees but more than 90 degrees. In some cases, the elbow may be a location comprising a bend of a greater angle than any other bends in the rest of the further extension arm. If the extension arm does not comprise a bend or is approximately linear, the support arm may terminate at a location on the further extension arm so as to provide stability between the structure 320 and the supportarm. The support arm may provide stability by preventing or reducing compression between the outer limits of the structure 320 and the further extension arm.

[0174] It can be seen in figure 22 that the support arms 2208a, 2208b may be planar in shape. The support arms may be twisted along their longitudinal axis. This twist may provide additional resistance to compression. The twisting may also provide a rotational bias to help maintain a desired rotational alignment between the structure 320 and the frame 102. The width and thickness of the planar structure of the support arms may be selected to minimise bending under compression and / or change the frequency of and / or dampen resonant vibrations in the dental splint.

[0175] The dental splint may comprise a second pair of support arms 2210a, 2210b. Each of the second pair of support arms 2210a, 2210b extend from the at least one extension arm 2108 and terminate on a respective one of the two further extension arms 2204a, 2204b. The second pair of support arms may be positioned and configured to reduce compression and flexion around the join at the base of each further extension arm 2204 where they attach to the at least one extension arm 2108.

[0176] In an example embodiment, the arcuate jaw clamp may be a maxillary arcuate jaw clamp 2200 comprising: a protrusion 2212 extending from the proximal end of the at least one extension arm 2108 in a direction opposite to and away from the bridge 2106, and at least one first wedge 2214 protruding from an occlusal surface adjacent to the first recess 2102 and / or the second recess 2104. In this embodiment the dental splint, and the above-described features, are configured to attach the arcuate jaw clamp to the maxillary dental arc (as illustrated in accompanying figures). However, it should be understood that the above-described features are not limited to be being implemented in a maxillary arcuate jaw clamp and may also be implemented in a mandibular arcuate jaw clamp configured to fit a mandibula dental arch.

[0177] A focused edge 2216 of the at least one first wedge 2214 may be orientated parallel to the bridge 2106 of the arcuate jaw clamp 102. That is, the leading edge 2216 of the at least one first wedge 2214 may run approximately parallel to the longitudinal axis ofthe bridge 2106. Thus, the wedge may be configured to have a leading edge 2216 which lies perpendicular to the direction of motion of the mandible during protrusion.

[0178] Figure 23 shows a top view of an example mandibular portion 2300 of the dental splint 2200. The dental splint may comprise a mandibular portion. The mandibular portion 2300 may be configured to extend over the dental arch of the subject's mandible. The mandibular portion 2300 may comprise a bridge 2302 extending between the two quadrants of the mandibular dental arch. The bridge 2302 may comprise a niche 2304 shaped to receive the protrusion 2212 and configured to prevent lateral excursion of the mandible. The mandibular portion 2300 may comprise at least one second wedge 2306 protruding from a molar occlusal surface of the mandibular portion. The at least one second wedge 2306 may be shaped to receive and abut the at least one first wedge 2214 protruding from the occlusal surface adjacent to the first recess and / or the second recess of the maxillary arcuate jaw clamp to prevent protrusion of the mandible.

[0179] That is, the at least one first wedge 2214 and the at least one second wedge 2306 are configured to cooperate to prevent protrusion of the mandible relative to the maxillary dental arch. This prevention comprises preventing translation of the mandible forward due to the abutment of the at least one second wedge 2306 on a rear surface of the at least one first wedge 2214.

[0180] The at least one second wedge 2306 may comprise a plateau or dip in a front face configured to make contact with the focused edge 2216, and in some embodiments a rear surface, of the at least one first wedge 2214. The dip may thus receive the leading edge of the first wedge 2214 and be configured to also prevent retrusion of the mandible. That is, the at least one second wedge 2306 may comprise a front face having a stepped profile. The at least one second wedge 2306 may comprise a front face having a side-profile whereby a portion has a gradient opposite to that of the taper of the second wedge 2306. That is, as the second wedge 2306 tapers to meet the surface of the mandibular portion 2300, the front face of the second wedge, which may comprise a dip for the leading edge 2216 of the first wedge 2214 to sit in, may comprisea portion which has a gradient which is opposite to that of the taper of the second wedge. Therefore, the first and second wedges together may be configured to stop protrusion. They may also limit retrusion thanks to the angle of the second wedge.

[0181] The bridge 2302 may be configured to reinforce the mandibular portion 2300. The niche 2304 may comprise a trench which runs perpendicular to the bridge of the mandibular portion. Accordingly, the niche 2304 may be trench shaped, thus allowing flexibility in the direction of protrusion and retrusion, but preventing lateral excursion due to the two contact points between the protrusion 2212 extremity and the walls of the trench shaped niche 2304. The walls of the niche 2304 may be sloped. In an example, the niche 2304 may have a V-shaped cross-section. The niche 2304 may thus take the form of a triangular prism. In another example, the niche 2304 may be a trapezoidal prism.

[0182] The term splint is used to convey a sense of immobility, but also as it implies that the apparatus it fits the subject's specific dentition. It is also this characteristic that allows the two jaws to be fixed securely within the apparatus and relative to each other and further prevent movement of the mandible in addition to the described wedge and protrusion systems. That is, the arcuate jaw clamps may be shaped to fit the subject’s specific dentition and thus fit the teeth in an immovable fashion.

[0183] Figure 24 shows a perspective view of an example mandibular portion 2300 of the dental splint. The mandibular portion 2300 may comprise a suction cannula 2402 extending around and between two ends of the mandibular dental arch. The suction cannula 2402 may comprise at least one outlet channel 2404 protruding perpendicular to the suction cannula and configured to terminate outside of the subject's mouth. That is, the outlet channel 2404 may protrude from the body of the suction cannula 2402 at a right angle. The outlet channel 2404 may be of a length and shape such that it terminates outside of the subject’s mouth when the mandibula portion is in use.

[0184] The mandibular portion 2300 may comprise a plurality of openings 2406 towards at least one end of the suction cannula 2402. The at least one end of the suction cannula2402 may be located adjacent to at least one of the two ends of the mandibular dental arch. The at least one end of the suction cannula 2402 may also be adjacent to soft tissue of the subject, e.g. the inside of a cheek and / or gums. The at least one end of the suction cannula 2402 may comprise a plurality of openings located toward one or both ends of the suction cannula 2402. The location and number of openings 2406 can be configured to optimise the removal of saliva from the mouth of the subject. The location and number of openings 2406 may be configured to limit the suction effect on the subject’s soft tissue at these openings. One or more of the plurality of openings may be located on the sides of the at least one end of the cannula to release suction. An opening may be provided on the very end of the at least one end of the cannula. That is, openings 2406 may be provided on multiple opposite sides of the end of the cannula to provide air inlets to release suction in multiple different directions when placed against tissue on an opposing or adjacent side. This is particularly important when the suction cannula is provided as a contiguous part of the splint as the cannula ends are stationary and do not move around like a typical suction cannula to release the suction. Therefore, the plurality of openings may be located on the end and on at least one side of the at least one end of the suction cannula. That is, the at least one end of the cannula may have the plurality of openings implemented as a combination of an opening on the end and one or more openings on the sides of the at least one end of the suction cannula. By preventing accumulation of saliva, instances of swallowing and coughing by the subject may also be reduced, in turn reducing the motion of the subject. The channel 2404 may be configured to be connected to an aspiration system.

[0185] Figure 25 shows a side perspective view of an example dental splint comprising a maxillary arcuate dental splint 2200 with mandibular portion 2300. The maxillary jaw clamp and mandibular potion are shown with approximate relative locations as though in place in a subject’s mouth but are not engaged with each other.

[0186] Figure 26 shows a front perspective view of an example dental splint comprising a maxillary arcuate jaw clamp 2200 with mandibular portion 2300. When the dental splint is viewed from this direction it is possible to appreciate the shape of the furtherextension arms 2204a, 2204b, which may be shaped to provide access to facial surfaces of the central teeth of the maxillary dental arch. The forked portions of the at least one extension arm 2108 may increase in thickness towards the structure 320. This shape may provide increased dampening of motion and increased rigidity parallel to the thickest dimension. Planar shaped branches, support arms, and extension arms may be implemented to align better with dimensions of elements to which they are fixed at each end. As mentioned above, twists in these structures may be implemented to provide torque against anticipated rotational motion and / or vibration.

[0187] Figure 27 shows a side perspective view of an example dental splint comprising a maxillary arcuate jaw clamp 2200 with mandibular portion 2300. In this example configuration, the maxillary jaw clamp and the mandibular portion are engaged as though in the subject’s mouth. The subject may be biting down. By an action of the subject biting down, the at least one first and second wedges 2214, 2306 and the protrusion 2212 and niche 2304 may be forced into their respective engaging positions. Stabilisation is provided against protrusion by the at least one first and second wedges 2214, 2306 and further stabilisation is provided against lateral excursion by the protrusion 2212 and niche 2304.

[0188] The arcuate jaw clamps and other moulded elements of the dental splint may be flexible. The degree of flexibility may be determined by the materials used to form the moulded parts. The moulded parts may be patient specific. Thereby, the moulded parts may be shaped to fit the specific dentition of a particular person. The arcuate jaw clamps and frame may therefore sit in place around the subject’s teeth in dependence on the flexibility of the moulded parts and the ability of those parts to sit flush against the contours of the specific dentition. By being able to sit close to the surfaces of the teeth and gums of the subject, a natural suction onto the teeth of the dental arch and / or gums may facilitate and secure positioning.

[0189] Where embodiments cover a significant portion of the subject’s dentition, e.g. exposing facial surfaces of about 6 teeth of a single dental arch, the frame or arcuate jaw clamp may be more difficult to remove than when covering a lesser proportion of the subject’sdentition, e.g. exposing facial surfaces of about 10 teeth. Thus, when covering more teeth of the dental arch, it may be necessary to provide slot 302 and join 210 to increase flexibility, reduce suction, and facilitate easy instillation and removal. Accordingly, locking pieces may be necessary to hold the dental splint in place on the teeth once installed.

[0190] Embodiments of the dental splint which cover fewer teeth (i.e. expose more teeth to work on), may be provided with a bridge which provides a more complete palate portion, sitting within the roof of the subject’s mouth. As such, the overall maxillary arcuate jaw clamp may be more rigid, enabling the splint to stay securely in place with only a biting action of the subject without locking pieces. Similarly, by implementing an entire palate to cover one dental arch, the dental splint may have increased rigidity, which may in turn keep the splint on the teeth by exerting force against teeth on both sides of the dental arch.

[0191] During installation, the moulded elements may be able to spread apart before being put in place and released to grip the teeth. As discussed above, some patients do not have a significant undercut at the base of their teeth / curved part at the gum line. In this case, the gripping provided by the clamping elements is less effective. However, in such cases, embodiments with the three contact points as described above (i.e. between one or more pairs of wedges and at least one protrusion and niche configuration), are important for increasing the security of the fit and rigidity through the action of biting.

[0192] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evidentto a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

43CLAIMS1. A dental splint for providing a positional reference with respect to a specific dentition of a subject, the splint comprising:a frame having a first clamping element and a second clamping element movable with respect to the first clamping element to mechanically grip a first tooth of the subject; anda first extension arm rigidly attached to the frame and extending from the frame for supporting a reference unit at a location outside the oral cavity of the subject when the frame is gripping the first tooth.

2. The dental splint as claimed in claim 1 , wherein the first clamping element is integral with the second clamping element, and the first and second clamping elements are flexibly interconnected such that the first and second clamping elements can be urged towards each other to grip the first tooth.

3. The dental splint as claimed in claim 2, the splint comprising a locking piece sized to be engageable against the first and second clamping elements to urge the first and second clamping elements into contact with the first tooth.

4. The dental splint as claimed in claim 3, wherein the locking piece defines a channel having side walls that can be engaged against the first and second clamping elements to urge the first and second clamping elements into contact with the first tooth.

5. The dental splint as claimed in claim 3 or 4, wherein the locking piece is configured to releasably latch to the first and second clamping elements for holding it in engagement with the first and second clamping elements.

6. The dental splint as claimed in any of claims 3 to 5, wherein the locking piece is non-integral with the clamping elements.

447. The dental splint as claimed in any of claims 3 to 6, wherein the locking piece comprises a shoulder configured to engage a post located elsewhere on the dental splint for retaining the locking piece on the dental splint when not latched to the first and second clamping elements.

8. The dental splint as claimed in any preceding claim, the frame having a third clamping element and a fourth clamping element movable with respect to the third clamping element to mechanically grip a second tooth of the subject, the second tooth being on the opposite quadrant of the same jaw to the first tooth.

9. The dental splint as claimed in claim 8, the splint comprising a second locking piece sized to be engageable against the third and fourth clamping elements to urge the third and fourth clamping elements into contact with the second tooth.

10. The dental splint as claimed in claim 8 or 9, wherein the first extension arm is attached to the frame adjacent the first and second clamping elements and the splint comprises a second extension arm for supporting the reference unit at a location outside the oral cavity of the subject when the frame is gripping the second tooth, the second extension arm being rigidly attached to the frame adjacent the third and fourth clamping elements.

11. The dental splint as claimed in any of claims 8 to 10, wherein:one of the first and second clamping elements has a leading end and a trailing end, the trailing end being cupped so as to engage the occlusal surface of the first tooth and thereby limit insertion of the first tooth between the first and second clamping elements;one of the third and fourth clamping elements has a further leading end and a further trailing end, the further trailing end being cupped so as to engage the occlusal surface of the second tooth and thereby limit insertion of the second tooth between the third and fourth clamping elements;the leading end and the further leading end lie in a common planar zone; and45the frame comprises a bridge extending between (i) the first and second and (ii) the third and fourth clamping elements, the bridge being located no closer to the cupped regions of the first to fourth clamping elements than the common planar zone.

12. The dental splint as claimed in any preceding claim, wherein the or each extension arm carries a structure for releasably receiving the reference unit.

13. The dental splint as claimed in any of claims 1 to 11 , wherein the or each extension arm carries the reference unit.

14. The dental splint as claimed in any preceding claim, wherein the reference unit is an optical reference unit comprising a plurality of optical reference sites.

15. The dental splint as claimed in claim 14, wherein each optical reference site comprises a recess for releasably receiving a reflector and a key surface shaped for fixing the position of the reflector relative to the frame.

16. The dental splint as claimed in claim 14 or 15, wherein the optical reference unit has at least three optical reference sites, the optical reference sites being located so as to be coplanar and not all collinear.

17. The dental splint as claimed in any of claims 1 to 13, wherein the reference unit is an inertial reference unit or a magnetic reference unit.

18. The dental splint as claimed in any preceding claim, the splint being arranged so that when the first tooth or the second tooth is a molar or premolar of the subject, the splint does not occlude the facial surfaces of the incisors of the same dental arch as the first tooth.

19. The dental splint as claimed in any preceding claim, wherein the first and second clamping elements, and the third and fourth clamping elements are shaped to match the contours of molars and / or premolars of a subject.

20. The dental splint as claimed in any preceding claim, wherein the first tooth or the second tooth is of a first dental arch of the subject and the splint comprises a jaw plate for engaging the other dental arch of the subject, the jaw plate being releasably attachable to the frame in a position to engage the other dental arch and thereby restrict motion of the jaws of the subject towards each other.

21. The dental splint as claimed in claim 20, wherein either the frame or the jaw plate comprises a tongue restraint for restraining the tongue of the subject.

22. The dental splint as claimed in claim 20 or 21 , wherein either the frame or the jaw plate comprises a formation for holding a suction tube in the subject’s oral cavity.

23. The dental splint as claimed in any preceding claim, wherein the or each extension arm comprises a stabilising branch, each stabilising branch disposed between:the first extension arm and the first / second clamping element; and / or the second extension arm and the third / fourth clamping element.

24. A method for providing a positional reference with respect to dentition of a subject, the method comprising:causing a dental splint as claimed in any preceding claim to grip a tooth of the subject; andimaging a reference unit carried by the or each extension arm of the dental splint.

25. The method as claimed in claim 24, the method comprising:forming the first and second clamping elements to match the contours of the first tooth of the subject or forming the third and fourth clamping elements to match the contours of the second tooth of the subject.

26. The method as claimed in claim 25, the method comprising:scanning the first tooth or second tooth so as to form a set of three-dimensional data representing the shape of the first tooth or second tooth; andforming the first and second clamping elements or the third and fourth clamping elements in dependence on the set of three-dimensional data.

27. The method as claimed in claim 26, comprising forming the first and second clamping elements or the third and fourth clamping element by additive manufacturing.

28. A dental splint comprising:an arcuate jaw clamp extending around an arc of greater than 120 degrees and having a first recess at one end thereof and a second recess at the other end thereof, each recess having at least one side wall for contacting a lateral surface of at least one tooth of a subject and a basal surface extending transversely to the side wall for contacting occlusal surfaces of at least one tooth in the recess for limiting the insertion of at least said tooth into the recess in a first direction;wherein both the basal surfaces lie on a common basal plane and the jaw clamp has a bridge extending between the first recess and the second recess, a central region of the bridge extending, on the convex side of the arc, no further in a direction opposite to the first direction than the basal plane.

29. The dental splint as claimed in claim 28, wherein each recess comprises a first clamping element and a second clamping element, the clamping elements of each recess being moveable with respect to each other to mechanically grip a tooth of the subject located in the respective recess.

30. The dental splint as claimed in claim 28 or 29, wherein the splint comprises at least one extension arm rigidly attached to the arcuate jaw clamp and extending from the arcuate jaw clamp for supporting a reference unit at a location outside the oral cavity of the subject when the arcuate jaw clamp is engaged with one or more teeth in the recesses.

31. The dental splint as claimed in claim 30, wherein the extension arm carries a structure for releasably receiving the reference unit.

32. The dental splint as claimed in claim 30, wherein the extension arm carries the reference unit.

33. A dental splint comprising:an arcuate jaw clamp extending around an arc of greater than 120 degrees and having a first recess at one end thereof for receiving a first molar or premolar of a subject, and a second recess at the other end thereof for receiving a second molar or premolar of the subject, the first and second molars or premolars being in the same dental arch but different quadrants thereof;the jaw clamp comprising a bridge extending between the first recess and the second recess and shaped such that when the first recess receives the first molar or premolar and the second recess receives the second molar or premolar, the bridge does not occlude the facial surfaces of the incisors of the said dental arch.

34. The dental splint as claimed in claim 33, wherein the splint comprises at least one extension arm rigidly attached to the arcuate jaw clamp and extending from the arcuate jaw clamp for supporting a reference unit at a location outside the oral cavity of the subject when the arcuate jaw clamp is engaged with one or more teeth in the recesses.

35. The dental splint as claimed in claim 34, wherein the extension arm carries a structure for releasably receiving the reference unit.

36. The dental splint as claimed in claim 34, wherein the extension arm carries the reference unit.

37. The dental splint as claimed in any of claims 33 to 36, wherein the bridge is shaped to fit within the curve of the roof of the subject’s mouth and / or within the dental arch.4938. The dental splint as claimed in any of claims 33 to 37, wherein the at least one extension arm is attached to the arcuate jaw clamp at a proximal end by a plurality of branches arranged to dampen vibrations between the arcuate jaw clamp and the extension arm.

39. The dental splint as claimed in any of claims 33 to 38, wherein the plurality of branches comprises a first and a second branch which extend from the proximal end of the at least one extension arm and are fixedly attached to the jaw clamp adjacent to the first and second recesses respectively.

40. The dental splint as claimed in any of claims 33 to 39, wherein the plurality of branches comprises a third branch which is fixedly attached to the bridge and splits into a fourth and a fifth branch, where each of the fourth and fifth branch extend from the distal end of the third branch towards the proximal end of the at least one extension arm.

41. The dental splint as claimed in any of claims 33 to 40, wherein the plurality of branches comprises a sixth branch which extends from the proximal end of the at least one extension arm and terminates at the distal end of the third branch.

42. The dental splint as claimed in any of claims 33 to 41, wherein the dental splint comprises a brace positioned between the first branch and the second branch and orientated perpendicularly to the at least one extension arm.

43. The dental splint as claimed in any of claims 33 to 42, wherein the at least one extension arm is forked at a distal end for supporting the reference unit.

44. The dental splint as claimed in any of claims 33 to 43, wherein the dental splint comprises two further extension arms, where each further extension arm is fixed at its distal end to a distal portion of the at least one extension arm supporting the reference unit and at a proximal end to a curved rail, the curved rail rigidly attached at its ends to the arcuate jaw clamp at points adjacent to the first and second recesses.5045. The dental splint as claimed in claim 44, wherein the dental splint comprises a first pair of support arms, wherein each support arm extends from the structure for releasably receiving the reference unit and terminates at a respective elbow of one of the two further extension arms.

46. The dental splint as claimed in claim 44 or 45, wherein the dental splint comprises a second pair of support arms, where each of the second pair of support arms extend from the at least one extension arm and terminate on a respective one of the two further extension arms.

47. The dental splint as claimed in any of claims 33 to 46, wherein the arcuate jaw clamp is a maxillary arcuate jaw clamp comprising:a protrusion extending from the proximal end of the at least one extension arm in a direction opposite to and away from the bridge, andat least one first wedge protruding from an occlusal surface adjacent to the first recess and / or the second recess.

48. The dental splint as claimed in claim 47, wherein a focused edge of the first wedge is orientated parallel to the bridge of the arcuate jaw clamp.

49. The dental splint as claimed in claim 47 or 48, wherein the dental splint comprises a mandibular portion extending over the dental arch of the subject's mandible and comprising:a bridge extending between the two quadrants of the mandibular dental arch, the bridge comprising a niche shaped to receive the protrusion and configured to prevent lateral excursion of the mandible; andat least one second wedge protruding from a molar occlusal surface of the mandibular portion, the at least one second wedge being shaped to receive and abut the at least one first wedge protruding from the occlusal surface adjacent to the first recess and / or the second recess of the maxillary arcuate jaw clamp to prevent protrusion of the mandible.

50. The dental splint as claimed in claim 49, wherein the mandibular portion comprises a suction cannula extending between two ends of the mandibular dental arch, the suction cannula comprising:at least one outlet channel protruding perpendicular to the suction cannula and configured to terminate outside of the subject's mouth; anda plurality of openings towards at least one end of the suction cannula located adjacent to at least one of the two ends of the mandibular dental arch.

51. The dental splint as claimed in claim 50, wherein the channel is configured to be connected to an aspiration system.

52. The dental splint as claimed in claim 50 or 51, wherein the plurality of openings are located on the end and on one or more sides of the at least one end of the suction cannula.

53. The dental splint as claimed in any of claims 49 to 52, wherein the niche comprises a trench which runs perpendicular to the bridge of the mandibular portion.

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