Reversion and prevention of peri-implantitis

Abstract

An intraoral device 16 for treatment of peri-implantitis has a head 20 that supports an optical engine 22. The optical engine comprises an enclosure for accommodating a dental implant in vivo and ligh

Description

This invention relates to techniques and devices for reversion and prevention of peri-implantitis. Some aspects of the invention involve intraoral or in vivo treatment of dental implants to reverse, mitigate or cure peri-implantitis but other aspects of the invention may involve in vitro treatment of dental implants to prevent peri-implantitis. For these purposes, aspects of the invention contemplate technologies for the design and assembly of a novel UVC light-emitting intraoral device. Peri-implantitis is a condition that causes gum inflammation and subsequent bone loss. The condition affects about 20% of dental implant patients globally and potentially leads to implant failures. While there are various well-understood reasons for the occurrence of peri-implantitis, a factor that is less well understood is the surface characteristics of a dental implant. Titanium is the most common material for dental implants due to its durability and strength, although other materials such as zirconia may be preferred for crowns to the benefit of appearance. Such implant materials have the ability to fuse to bone in a beneficial process known as osseointegration. For osseointegration to be successful, fluids and proteins from the surrounding cells in the implant area must be attracted to the surface of the implant to form bonds. The degree of attraction, or hydrophilicity, depends upon the characteristics of the implant surface, such as its texture or composition, and is susceptible to be reduced by any contaminants that may be on that surface. It is known that implants can age biologically within days of being manufactured, with surface hydrocarbons appearing even before placement in a patient’s jaw. This ageing process causes the implant surface to become hydrophobic, reducing the chances of successful osseointegration. To improve the hydrophilicity of an implant surface before placement of the implant, the surface can be roughened before placement using techniques such as sand blasting, acid etching or anodization. Another way of improving implant hydrophilicity in vitro is to expose the surface to UVC light, typically with a wavelength of 100 nm to 282 nm, which removes surface hydrocarbons in a process known as photo-functionalisation. UVC lamps represent the current technology for photo-functionalising implants in vitro. It is known from various studies that using UVC light on implants in vitro improves hydrophilicity and therefore cell adhesion, potentially reducing the prevalence of peri-implantitis. Regardless of implant materials or treatments adopted pre-placement to reverse ageing and to improve hydrophilicity, all dental implants will age after placement in the mouth. This hinders the ability of the implant to osseointegrate, hence increasing the risk that peri-implantitis will occur. In addition, the implant surface attracts organic contaminants in addition to hydrocarbons, leading potentially to a buildup of bacteria around the implant area that can cause gum inflammation. UVC light can potentially remove or otherwise combat such contaminants as they absorb light in the UVC wavelength range. As known implant treatment methods focus on treating an implant in vitro, there remains a need for an intraoral device to treat an implant by photo-functionalisation in vivo. In addition, there is no known prior art that uses UVC light to sterilise the implant area intraorally, hence in vivo. Current UVC lamps operate at a wavelength of 255 nm, which is known to have both photo-functionalisation and germicidal properties. However, it is unclear if this is the most beneficial wavelength for those effects within the UVC range. In addition, wavelengths above 240 nm could potentially damage surrounding gum tissue around the implant site, especially if the exposure time is too long. It is against this background that the present invention has been devised. From one aspect, the invention resides in an intraoral device for treatment of peri-implantitis, the device comprising a head supporting an optical engine that comprises an enclosure for accommodating a dental implant in vivo and at least one light emitter configured to emit UVC light into the enclosure. The or each light emitter may, for example, be configured to emit UVC light at a wavelength in a range from 170 nm to 280 nm. The enclosure suitably encircles an aperture for receiving and surrounding the dental implant. At least one shielding formation may be disposed between the or each light emitter and an edge or boundary of the aperture. At least one reflector may also be provided within the enclosure. The or each light emitter can face toward a central axis extending along the enclosure. For example, the or each light emitter may be curved around an axis of curvature extending along the enclosure. Two or more light emitters may be angularly spaced around the enclosure, for example being angularly spaced around an axis or axes extending through the aperture. Where at least one jaw is movable to open and close the enclosure, at least one of the light emitters can be mounted on the or each jaw. The or each jaw can be movable relative to a housing, in which case at least one of the light emitters can be fixed relative to the housing. The or each light emitter can extend across a flexible substrate or a substantially rigid substrate. For example, the or each light emitter may comprise an LED array in which, for example, high-wavelength LEDs are configured to emit UVC light at a relatively high wavelength and low-wavelength LEDs are configured to emit UVC light at a relatively low wavelength. The low-wavelength LEDs may, for example, be configured to emit UVC light at a wavelength of 260 nm or less, or 240 nm or less. The or each light emitter may further comprise at least one supplementary array at an edge of the LED array, the supplementary array comprising low-wavelength LEDs additional to those of the LED array. The LEDs of the supplementary array may be oriented to emit light substantially orthogonally to those of the LED array. The low-wavelength LEDs and high-wavelength LEDs may be separated into respective groups. For example, the low-wavelength LEDs and high-wavelength LEDs can be grouped into respective rows. More generally, the low-wavelength LEDs and high-wavelength LEDs can be disposed in mutual alternation across the LED array. The or each light emitter may comprise an optical waveguide, and can further comprise at least one light source edge-coupled to the waveguide. The waveguide can be curved to define an intrados and an extrados, the intrados being light-emitting and the extrados being internally-reflecting. An optical amplifier can be interposed between the or each light source and the waveguide. Two or more light sources can be coupled to respective edges of the waveguide. Those light sources may be configured to emit UVC light at respectively different wavelengths. A device of the invention may further comprise an electronics engine that is configured to drive the optical engine and to control power and / or wavelength of UVC light emitted by the optical engine. A timer may be configured to monitor an exposure period of the optical engine and / or to adjust the exposure period in response to power and / or wavelength settings of UVC light emitted by the optical engine. The inventive concept also embraces a method of treating a dental implant, the method comprising: forming an enclosure around the implant; and exposing the implant to UVC light emitted into the enclosure. The implant can be exposed to UVC light around a full circumference of the implant. The method can be performed in vitro but is apt to be performed in vivo, hence intraorally upon an implant already implanted in a patient, in which case gum tissue and bone may be shielded from the UVC light emitted into the enclosure. The UVC light can be emitted into the enclosure at a relatively high wavelength but can be emitted toward gum tissue and bone at a relatively low wavelength of, for example, 260 nm or less, or 240 nm or less. After opening a gap in the enclosure, the implant can be admitted into the enclosure through the gap and then the gap can be closed to close the enclosure around the implant. A crown fixed to the implant can also be admitted into the enclosure. The invention provides a UVC light-emitting device that can photo-functionalise a dental implant and / or sterilise the implant area and that can be used both in vitro and intraorally to prevent or cure peri-implantitis, depending on the stage at which treatment takes place. For these purposes, it is beneficial to have a multi-wavelength source that emits light at two or more wavelengths, in which at least one of the emitted wavelengths can be used for intraoral sterilisation and is safe for operation over a sufficiently long duration in areas of the mouth that surround the implant. Embodiments of the invention relate to platform architecture and process steps for assembling and using an intra-oral UVC-emitting device. The device is apt to be effective primarily in early-stage treatment of peri-implantitis. With the device hand-held or otherwise supported, the optical engine is designed to be held in a localised position close to and preferably around the implant site. The optical engine accesses the implant site via a suitable attachment or engagement means, which may for example involve one or more movable jaws such as a mini-forceps arrangement to embrace or encircle the implant without necessarily removing a crown attached to the implant. For optimal form factor design, the optical engine may comprise flexible or substantially rigid supports for UVC light sources such as LEDs. For photo-functionalisation of a dental implant, LEDs used in the optical engine of the device may, for example, emit light at wavelengths in the range 220 nm to 280 nm. Conversely, for sterilisation of an implant region, LEDs used in the optical engine may, for example, emit light at wavelengths in the range 170 nm to 260 nm and preferably below 240 nm. Thus, the optical engine can employ a variety of light source configurations for photo-functionalising the dental implant and / or for disinfecting or sterilising the implant region. The optical engine may, for example, comprise micro LEDs mounted on or embedded in a substrate, those light sources being positioned and operated in such a way as to minimise damage to the surrounding bone and / or tissue. There may be an option for selective wavelength and / or power operation of the device. In particular, the optical engine can employ LEDs of one wavelength or multiple wavelengths or LEDs with a tuneable or adjustable wavelength, depending upon the purpose of the light they emit. For example, the wavelength(s) of light output from the optical engine can be controlled by providing a wavelength-selection setting in the electronics engine. The optical output power of the optical engine can be varied by varying the number of light sources such as LEDs illuminated and / or by incorporating a power-selection setting in the electronics engine. Alternatively or in addition, the light sources in the optical engine can be biased in a continuous wave (CW) mode and / or in a pulsed mode. The ability to select the optical power output can change the exposure time required for either photo-functionalisation of the implant and / or for sterilisation of the implant region. A timer function may be included in the electronics engine to keep track of, and to limit, the exposure time appropriate to the selected optical power output. To dissipate heat generated from biased light sources such as LEDs, a cooling system can be incorporated into the device or a thermally dissipative layer can be deposited between the base of the LEDs and the substrate on which the LEDs are assembled. LEDs can be assembled on and fixed to a substrate by various techniques such as flipchip bonding or other suitable bonding method, or by embedding substrate techniques. Thus, the invention provides an intra-oral, single-function or multi-functional device that can combine sterilisation and / or photo-functionalisation capabilities without damaging a patient’s bone or surrounding tissue. For this purpose, the device may employ a multisource, multi-wavelength optical engine that includes light sources emitting light in the wavelength range 170 nm to 282 nm, but with at least some of those light sources emitting light at a wavelength in a lower end of that range, preferably of no greater than 240 nm. The light sources may be mounted on a substrate that is positioned for direct access or exposure to the implant. It is anticipated that a device of the invention can achieve excellent performance targets if used for treatment of implants, whether in vivo or in vitro, namely: a contact angle of less than 10° for improved hydrophilicity; a two-fold increase in cell attachment and density; and bone-implant contact of greater than 60%. The combination of the LEDs and the ability to select the required optical output power and therefore intensity of UVC radiation can allow these performance targets to be achieved with optimal exposure times that will minimise or avoid damage to surrounding tissue and / or bone. Thus, the invention provides design and platform technology for assembling an intra-oral UVC-emitting hand-held device for reducing the prevalence of, and curing, peri-implantitis. This device eliminates a technological gap for reversing ageing of implants by photo-functionalisation performed intra-orally, while also offering a potential additional functionality of sterilising the site of the implant area using UVC light. The invention therefore holds the promise of improving osseointegration after implant placement and could be used instead of Phase I treatment of peri-implantitis, reducing the need for invasive surgical procedures. In summary, the invention provides an intraoral device for treatment of peri-implantitis and a corresponding method of treating peri-implantitis. An optical engine of the device comprises an enclosure for surrounding or accommodating a dental implant in vivo and light emitters such as LED arrays or waveguides angularly spaced around the enclosure, configured to emit UVC light into the enclosure and hence toward the implant. One or more jaws are movable relative to a support or housing to open and close the enclosure. At least one of the light emitters can be mounted on the or each jaw and at least one other light emitter can be fixed relative to the housing that supports the or each jaw. High-wavelength light sources and low-wavelength light sources may be combined for photo-functionalisation of the implant and / or for sterilisation of the implant region. Optionally, at least one supplementary emitter on an edge or end of the enclosure comprises additional low-wavelength light sources and emits light away from the enclosure for sterilisation of the implant region. In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1a is a perspective view of a patient’s jaws including an implant region affected by peri-implantitis; Figure 1b corresponds to Figure 1a but shows the implant region opened up for intraoral treatment in accordance with the invention; Figure 2a is an exploded side view of a conventional implant, abutment and crown; Figure 2b corresponds to Figure 2a but shows the implant, abutment and crown assembled together; Figure 3 is a perspective view of an intra-oral, UVC-emitting device in a first embodiment of the invention; Figures 4a, 4b and 4c are enlarged perspective views of a head of the device shown in Figure 3; Figure 5 is a perspective view of the head of the device of Figure 3 showing a drive mechanism within the head; Figure 6 is a perspective view of the drive mechanism visible within the head in Figure 5; Figure 7 is a longitudinal section view of the head and drive mechanism shown in Figure 5; Figures 8a and 8b are enlarged perspective views of the drive mechanism shown in Figure 6; Figures 9a to 9d are schematic perspective views of a head of an intra-oral, UVC-emitting device in a second embodiment of the invention; Figure 10 is a schematic perspective view of the head shown in Figures 9a to 9d being used to treat an implant in vivo, Figures 11a to 11c are schematic bottom plan views of the head shown in Figures 9a to 9d; Figures 12a and 12b are perspective views of the head shown in Figures 9a to 9d, showing a drive mechanism within the head; Figure 13 is a plan view of the head corresponding to Figures 12a and 12b; Figure 14 is a perspective view of an intraoral, UVC-emitting device in a third embodiment of the invention, in use when treating a patient’s implant; Figure 15 is a perspective view of an intraoral, UVC-emitting device in a fourth embodiment of the invention; Figures 16a and 16b are perspective views of stacked LED arrangements for use in intraoral devices of the invention; Figures 17a to 17c are perspective views of LEDs arranged in rows on a curved substrate for use in intraoral devices of the invention, with LEDs of the same wavelength placed in the same rows or with LEDs of different wavelengths placed in the same rows; Figures 18a and 18b are perspective views of LEDs arranged in rows on a curved substrate for use in intraoral devices of the invention, with additional LEDs also arranged on a base edge of the substrate for sterilisation purposes; Figures 19a and 19b are perspective views of LEDs for use in intraoral devices of the invention, the LEDs being arranged in rows on multiple curved substrate layers stacked on top of each other; Figures 20a to 20c are elevation views of LEDs for use in intraoral devices of the invention, the LEDs being arranged in rows on a flat substrate, with LEDs of the same wavelength placed in each row or with LEDs of different wavelengths placed in the same rows; and Figure 21 is an elevation view of LEDs for use in intraoral devices of the invention, the LEDs being arranged in rows on multiple flat substrate layers stacked on top of each other. Referring firstly to Figures 1a and 1b, these drawings show dental implants 10 embedded in a patient’s mandible and surmounted by respective crowns 12. The shaded areas in Figure 1a indicate regions affected by peri-implantitis. Figure 1b shows the gum tissue cut back to open up the region around the implants 10 beneath the crowns 12 for intraoral treatment, in accordance with the invention, of the peri-implantitis affecting that region. Figures 2a and 2b show an abutment 14 that is conventionally interposed between an implant 10 and a crown 12. For simplicity, references to the implant 10 herein include any abutment 14 that may be employed. Figure 3 shows a device 16 of the invention for intraoral treatment of peri-implantitis. The device 16 comprises a proximal handle 18 and a distal probe or head 20 that may be fixed to or interchangeably attached to the handle 18. The head 20 comprises an optical engine 22 that is offset laterally from a distal end of an elongate post 24 extending distally from the handle 18. An electronics engine that controls the UVC light output of the optical engine 22 may conveniently be incorporated into the handle 18 but could instead be situated in the head 20. The electronics engine may, for example, comprise a UVC source module and driver and control electronics. A power supply for the electronics engine may be connected to an onboard battery or to an external power source via a flexible cable. Controls 26 on the handle 18 act on the electronics engine to turn the device 16 on and off and can also be used to select the wavelength(s) and / or optical power emitted by the optical engine 22. A display 28 on the handle 18 conveys the status of the device 16 to a user. As best appreciated in Figures 4a to 4c, the optical engine 22 comprises arrays 30 of LEDs 32 assembled on respective substrates or supports that are concave-curved about parallel or common axes to form an open-ended enclosure that encircles a central aperture 34 when the supports are brought together. When the implant region has been opened surgically as shown in Figure 1b, the curved supports can together fit around the crown 12 and around the implant 10 beneath the crown 12, hence together embracing or encircling the crown 12 and the implant 10 within the aperture 34. For this purpose, two of the supports are retractable forceps-like jaws 36 that are movable relative to the post 24 that holds the optical engine 22. The jaws 36 open and close symmetrically from respective sides of the implant 10. The jaws 36 are movable together and apart in mutual opposition about respective pivot axes that are either mutually parallel or, as in this case, common. When closing, the jaws 36 emerge from respective sides of an approximately semi-annular housing 38 and each jaw 36 turns through approximately 90° relative to the housing 38. The housing 38 contains curved tracks that guide the movement of the jaws 36 and that receive the respective jaws 36 when the jaws 36 are open. The jaws 36 can thereby be opened and then closed to fit around the implant 10 without removing the crown 12. Conveniently, the jaws 36 can be moved by an electric drive system that is powered by a motor in the handle 18 and controlled by controls on the handle 18, as will be explained. It would instead be possible to move the jaws 36 manually by grasping and operating a control element such as a knob on the handle 18 or on the head 20, as will also be explained. A further concave array 30 of LEDs 32 is provided on a central curved support 40 at the intrados of the semi-annular housing 38, between the jaws 36. The central support 40 is fixed relative to the post 24 and is curved about an axis common to, or parallel to, the pivot axes of the jaws 36. The example illustrated shows the optional addition of reflectors 42 on the housing 38 outboard of the fixed central support 40 and inboard of the movable jaws 36. Thus, when the jaws 36 are closed, the aperture 34 is substantially surrounded by concave-curved arrays 30 of LEDs 32 on the respective supports and optional reflectors 42, which arrays 30 and reflectors 42 face radially inwardly into the aperture 34 to provide 360° of UVC exposure around the implant 10. When activated to emit UVC light to illuminate a crown 12 and an implant 10 within the aperture 34, the arrays 30 of LEDs 32 can thereby remove hydrocarbons by photo-functionalising the implant 10 and / or sterilise the implant region and the surrounding area, including the crown 12. The composition and arrangement of the arrays 30 of LEDs 32 will be discussed further with reference to Figures 16a to 21. The semi-annular housing 38 of the optical engine 22 further comprises a heat sink 44 that curves around and behind the fixed central support 40 and that is thermally coupled to a radiator 46 extending across at least one face of the housing 38. By conduction and convection, the heat sink 44 and the radiator 46 remove heat from the optical engine 22 that is generated by the arrays 30 of LEDs 32, when activated. Turning to Figures 5 to 8b, these drawings show details of a drive for moving the jaws 36 of the optical engine 22 relative to the housing 38 and the post 24. A drive shaft 48 extends within and along the post 24 and comprises a splined coupling formation 50 at its proximal end for coupling to a rotary drive (not shown), which may comprise the aforementioned motor in the handle 18 or a manual control element such as a knob. In this way, the drive shaft 48 can be turned about its central longitudinal axis. At its distal end, the drive shaft 48 has a worm formation 52 that meshes with a parallel worm screw 54 disposed between the drive shaft 48 and the housing 38 of the optical engine 22. As best appreciated in the enlarged views of Figures 8a and 8b, the worm screw 54 is disposed between flanges 56 that are integral with the respective jaws 36. The worm screw 54 is meshed with mutually-opposed teeth 58 of the respective jaws 36, those teeth 58 being angularly spaced around the common pivot axis of the jaws 36 so that the jaws 36 serve as worm gears. The arrangement of the worm screw 54 and the teeth 58 of the respective jaws 36 is such that unidirectional rotation of the worm screw 54 acts in opposite circumferential directions on the respective jaws 36, hence driving the jaws 36 in mutual opposition around their common pivot axis. After closing or opening the jaws 36, the direction of drive applied to the drive shaft 48 and hence to the worm screw 54 is simply reversed to open or to close the jaws 36 as the case may be. Each jaw 36 extends around slightly more than 180° of arc and pivots through a range of about 90° between fully open and fully closed states. Any clash between the jaws 36 is avoided by one jaw 36 being of slightly smaller diameter than the other jaw 36. Thus, within the housing 38 at least, the narrower inner jaw 36 can nest within the wider outer jaw 36 as the jaws 36 overlap angularly upon opening. Figures 9 to 13 show the head 20 of another device of the invention for intraoral treatment of peri-implantitis. The handle of that device can be much the same as the handle 18 of the device 16 shown in the preceding embodiment and so need not be described further here. More generally, as this embodiment has some features in common with the preceding embodiment, like numerals will be used for like features. For example, a curved support 40 bearing a concave array 30 of LEDs 32 is again fixed and disposed centrally relative to a semi-annular housing 38. In the embodiment shown in Figures 9 to 13, however, there is only one movable jaw 36 that defines a movable support for a further concave array 30 of LEDs 32. The jaw 36 turns through about 180° relative to the housing 38 between fully open and fully closed states. When in the fully open state, a distal angular gap 60 between the opposed ends of the jaw 36 can admit a crown 12 and implant 10 toward the fixed central support 40, before the jaw 36 is pivoted to close around the crown 12 and implant 10, now within the aperture 34 thus defined between the jaw 36 and the fixed support 40 as shown in Figure 10. Thus, between them, the jaw 36 and the fixed support 40 form an open-ended enclosure that encircles the aperture 34. The jaw 36 is of greater diameter than the fixed support 40 so that when closed, the jaw 36 embraces and overlaps angularly with the fixed support 40. In this embodiment, the aperture 34 is defined at a distal end of the head 20 and opens through the distal gap 60 in an axial direction instead of being beside the distal end of the head 20 and opening in a lateral direction relative to the post 24 as in the preceding embodiment. Thus, the fixed support 40 with its concave array 30 of LEDs 32 faces axially in the distal direction. Conversely, the concave array 30 of LEDs 32 on the jaw 36 is mounted centrally to face axially in the proximal direction, hence in mutual opposition to the fixed support 40 across the aperture 34, when the jaw 36 is closed. Optional reflectors 42 are positioned on each side of the array 30 of LEDs 32 mounted on the jaw 36. As before, therefore, when the jaw 36 is closed, the implant 10 and a crown 12 are surrounded by the concave-curved arrays 30 of LEDs 32 and optional reflectors 42, which arrays 30 and reflectors 42 face radially inwardly into the aperture 34. When activated to emit UVC light to illuminate the crown 12 and the implant 10 within the aperture 34, the arrays 30 of LEDs 32 can thereby remove hydrocarbons by photofunctionalising the implant 10 and / or sterilise the implant region and the surrounding area. Again, the composition and arrangement of the arrays 30 of LEDs 32 will be discussed further with reference to Figures 16a to 21. As best appreciated in Figures 11a to 11 c, the fixed support 40 with its array 30 of LEDs 32 has a inwardly-extending flange 62 around the edge of the support that, in use, faces the bone embedding the implant 10, being the lower edge when used on an implant 10 in a patient’s mandible as shown in Figure 10. The corresponding edge of the jaw 36 also has an inwardly-extending flange 64 that lies in a plane beneath and parallel to the plane of the flange 62 of the fixed support. When the jaw 36 is closed as shown in Figures 11b and 11c, the flange 64 of the jaw 36 cooperates and overlaps with the flange 62 of the fixed support 40 to encircle the implant 10, narrowing the aperture 34 at that location to have a circular profile that fits closely around the implant 10. This helps to shield the gum tissues and bone around the implant region from direct exposure to higher-frequency UVC radiation emitted by the LEDs 32. The flanges 62, 64 may therefore be regarded as shielding formations of the optical engine 22. Shielding flanges 62, 64 like those provided on the fixed support 40 and the jaw 36 could also be employed on the jaws 36 and the fixed support 40 of the preceding embodiment shown in Figures 3 to 8b. Figures 9a to 11c represent the movable jaw 36 schematically whereas Figures 12a to 13 show details of a drive for moving the jaw 36 relative to the housing 38 and the post 24. Again, a drive shaft 48 extends within and along the post 24. The drive shaft 48 could be coupled to a rotary drive such as a motor in the handle 18 but in this case, the drive shaft 48 is turned about its central longitudinal axis by a manual control element exemplified here by a rotary knob 66 mounted on the post 24. The knob 66 turns about an axis transverse to the drive shaft 48. Thus, rotary drive is transmitted from the knob 66 to the drive shaft 48 via a bevel gear arrangement 68 at the proximal end of the drive shaft 48. At its distal end, the drive shaft 48 has a crown gear formation 70 that meshes with external teeth 58 on the jaw 36, spaced angularly through a range of slightly more than 180° around the pivot axis of the jaw 36. Thus, turning the drive shaft 48 by turning the knob 66 pivots the jaw 36 to turn relative to the housing 38 between fully open and fully closed states as required. As represented in Figures 12a to 13, the jaw 36 extends angularly beyond the array 30 of teeth 58, in this example through about 270° of arc. Thus, when in the fully open state shown in Figure 12a, a central portion of the jaw 36 is accommodated within the housing 38 and end portions of the jaw 36, defining the distal gap 60 between them, protrude from the distal end of the housing 38. As best appreciated in Figure 13, the housing 38 contains a curved track 72 that guides the movement of the jaw 36 and that can receive the central portion of the jaw 36 when the jaw 36 is open. Figure 14 shows an optical engine 22 of an intra-oral device placed around an implant region in a patient’s mouth. In this example, an array 30 of LEDs 32 is on a concave inner face of a U-shaped ribbon-like support 74, which could be substantially rigid or could be a flexible web. In the latter case, the web can be bent with a radius of curvature of 0.1 cm to 5 cm around a crown 12 and implant 10 through 90° to 360° of arc, which allows for fitting around the affected implant region. Any of the LED configurations disclosed herein can be arranged and bonded onto or embedded in one or more such substrates. Figure 15 also shows a concave-curved structure 76 for an optical engine 22. Again, the structure 76 could be flexible or substantially rigid, and could be used in isolation or as a movable jaw 36 of a device 16 like those described in the preceding embodiments. In this example, however, the structure 76 comprises a U-shaped ribbon-like waveguide 78 of an optical material that is considered to be transparent in the UVC range. The waveguide 78 may, for example, comprise any of the following materials: AIN; AlxGai-XN; a combination of AIN / AlxGai.xN; diamond; SiC; or GaO2. The materials of the waveguide 78 can also be doped or undoped, depending on the desired optical and / or electrical properties. The waveguide 78 may, for example, have a radius of curvature of 0.1 cm to 5 cm. In an edge-coupled arrangement, UVC light enters the waveguide 78 through at least one edge, preferably through at least one end edge of the waveguide 78 at the end of a leg of the U-shape. In this case, light enters through both end edges of the waveguide 78, hence through the opposed ends of the U-shape at the end of the legs. The light is generated by LEDs 32 with integrated lenses 80 to collimate and focus the light. The light is then amplified by respective semiconductor optical amplifiers (SOAs) 82 before entering the opposed ends of the waveguide 78. The LEDs 32 at the opposed ends of the waveguide 78 could emit light at the same wavelength as each other or at different wavelengths to each other. On its convex extrados or outer radius, the waveguide 78 has a reflective surface or a mirror element 84 to amplify light along the waveguide 78, to prevent outward leakage of light and instead to reflect the light radially inwardly across the waveguide 78. Conversely, on its concave intrados or inner radius, the inner face 86 of the waveguide 78 is roughened or otherwise textured or treated to extract light from the waveguide 78. The extracted light impinges on an implant 10 in use. Other surfaces of the waveguide 78 could also be configured to emit light if desired, such as either or both of the long edges of the waveguide 78 extending around the curve. The lenses 80, the SOAs 82 and the mirror element 84 shown in Figure 15 are examples of various optical elements that can be integrated into an optical engine 22 of the invention to manipulate UVC light. Examples of light manipulation include light filtering, light directionality, collimation, diffusion, attenuation and amplification. The ribbon-like supports of Figures 14 and 15 could encircle the crown 12 and implant 10 or could serve as a movable jaw 36 of a device 16 like those described in the preceding embodiments, potentially in conjunction with a fixed support 40 bearing another array 30 of LEDs 32. Figures 16a and 16b show how LEDs 32 of an array can be stacked on top of each other in a layered ‘notch’ configuration instead of being assembled sequentially. This design keeps the system more compact and can also increase the optical power for the fluence required, being the optical energy per unit area. Again, the LEDs 32 can emit light at the same wavelength as each other, as shown in Figure 16a, or at different wavelengths to each other, as shown in Figure 16b where the LEDs are designated as 32A and 32B respectively. Figures 17a to 19b show various arrays 30 of LEDs 32 on inner side walls of concave-curved substrates or supports 88 that could be used as jaws 36 or as fixed supports 40 in preceding embodiments. In each case, the LEDs 32 are arrayed in substantially parallel rows 90 extending around the curve, hence circumferentially around an axis of curvature of the support 88. In these examples, the LEDs 32 are also arrayed in columns 92 parallel to the axis of curvature, hence in a regular matrix array 30, although other regular or irregular arrangements are possible. In Figures 17a and 17b, each row 90 contains LEDs 32 of the same wavelength but the wavelengths emitted by the LEDs 32 vary from row to row. In these examples, the rows 90 alternate between LEDs 32A emitting a first wavelength and LEDs 32B emitting a second wavelength. In Figure 17a, a row 90 of LEDs 32B emitting a second wavelength is disposed between rows 90 of LEDs 32A emitting a first wavelength; conversely, Figure 17b shows a row 90 of LEDs 32A emitting a first wavelength disposed between rows 90 of LEDs 32B emitting a second wavelength. Thus, with multi-wavelength and multi-source functionalities, light sources such as LEDs 32 can be arranged in multiple rows 90 on the same layer, mounting substrate or support 88, and may be grouped in rows 90 by their wavelength of light emission. Thus, light sources emitting a first wavelength can be placed together in the same row 90 and light sources emitting a second wavelength can be placed together in another row 90. The grouping of light sources depending on their shared wavelength, such as placement of light sources in specific rows 90, mitigates a risk of crosstalk that could otherwise reduce the efficiency of this integrated light source system. It is also possible for at least one row 90 to contain LEDs 32 or other light sources emitting more than one wavelength between them. For example, Figure 17c shows the LEDs 32 of each row 90 alternating between LEDs 32A that emit UVC light at a first, higher wavelength and LEDs 32B that emit UVC light at a second, lower wavelength. In this example, the LEDs 32 of neighbouring rows 90 are staggered so that the LEDs 32 of each column 92 alternate similarly. Thus, rather than grouping the light sources in rows 90 of single wavelengths, the wavelength of the light sources can alternate along a row 90, i.e. with every second light source along the row 90 emitting at the first wavelength interleaved with every second light source along the row 90 emitting at the second wavelength. An alternating or otherwise mixed placement of different-wavelength light sources accesses the potential benefits of different parts of the UVC wavelength range, as the optimal wavelength for photo-functionalisation may lay elsewhere. Figures 18a and 18b show variants of the above arrangements in which supplementary LED arrays 94 are disposed on edges of the support 88. In this example, supplementary LED arrays 94 are disposed on either or both of the long edges of the support 88 extending around the curve, such as a base edge. LEDs 32 of the supplementary arrays 94 face the tissue and bone around the implant region and so are LEDs 32B, configured to emit light at a second, lower wavelength suitable for sterilisation purposes. The inwardly-facing array 30 of LEDs 32 on the concave face of the support shown in Figures 18a and 18b may be arranged in various mixed-wavelength configurations. The configurations shown in Figures 18a and 18b correspond to those shown in Figures 17b and 17c but the LEDs 32 could be in another configuration, such as that shown in Figure 17a. More generally, therefore, light sources emitting lower wavelengths can be offset toward or placed at or near to an edge of a support 88, for example toward a base or bottom edge of the support 88 facing a patient’s mandible, so as to have greater sterilising impact on an inflamed implant region. The lower-wavelength light sources emit light within a wavelength range of, say, below 240 nm, which is deemed to be safe for exposure of gum tissue and bone and so minimizes any risk of damage to the area of, and surrounding, the implant region. Nevertheless, due to the design of the head 20, the light sources on the concave side wall of a support 88 can safely emit light in wavelengths that are suitable for both photo-functionalisation and sterilisation. Figures 19a and 19b show deeper or wider supports 88 whose arrays 30 comprise additional rows 90 of LEDs 32, which could be defined by multiple curved substrate layers stacked on top of each other. In Figure 19a, a pair of rows 90 of LEDs 32B that emit a second wavelength is disposed between two pairs of rows 90 of LEDs 32A that emit a first wavelength. In Figure 19b, rows 90 alternate from row 90 to row 90 between LEDs 32A that emit a first wavelength and LEDs 32B that emit a second wavelength. Thus, rather than arranging light sources on a single layer or mounting substrate, a support 88 may comprise stacked layers with light sources of a single wavelength in each layer, for example, light sources emitting a first wavelength in a first layer, light sources emitting a second wavelength in a second layer, light sources emitting a first wavelength in a third layer, and so on. Like Figures 18a and 18b, Figure 19b also shows supplementary LED arrays 94 disposed on either or both of the long edges of the support 88 extending around the curve. Again, the LEDs 32 of the supplementary arrays 94 face the tissue and bone around the implant region and so are LEDs 32B configured to emit light at a second wavelength. The LEDs 32 in Figures 19a and 19b emit light at the same wavelength along each row 90. However, like Figure 17c, the LEDs 32 of any row 90 could instead alternate between LEDs 32A that emit a first wavelength and LEDs 32B that emit a second wavelength. Turning finally to Figures 20a to 20c and Figure 21, these drawings show that substrates or supports 96 for arrays of LEDs 32 need not necessarily be curved but could instead be substantially flat or planar. Two or more such supports 96, preferably three, four or more such supports 96, could be used together at relative face-to-face orientations appropriate to surround a crown or an implant. At least one of those supports 96 could be movable relative to another of those supports 96 to admit a crown or an implant into an aperture defined between the supports 96. Again, Figures 20a to 20c and Figure 21 represent the arrays 30 of LEDs 32 as comprising parallel rows 90 and columns 92 in a regular matrix, although other regular or irregular arrangements are possible on a flat substrate. The arrangements of Figures 20a to 20c correspond to those shown in Figures 17a to 17c. In Figures 20a and 20b, each row 90 contains LEDs 32 that emit the same wavelength but the wavelengths emitted by the LEDs 32 vary from row 90 to row 90 between a first wavelength and a second wavelength. In Figure 20a, a row 90 of LEDs 32B emitting a second wavelength is disposed between rows 90 of LEDs 32A emitting a first wavelength whereas in Figure 20b, a row 90 of LEDs 32A emitting a first wavelength is disposed between rows 90 of LEDs 32B emitting a second wavelength. Conversely, Figure 20c shows the LEDs 32 of each row 90 alternating between LEDs 32A that emit a first wavelength and LEDs 32B that emit a second wavelength. Finally, like Figures 19a and 19b, Figure 21 shows a deeper or wider support 96 whose array 30 comprises additional rows 90 of LEDs 32, which could be defined by multiple flat substrate layers stacked on top of each other. In Figure 21, for example, the substrate comprises a stack of two of the arrays 30 shown in Figure 20a sandwiching one of the arrays 30 shown in Figure 20b, each array 30 having three rows 90 of LEDs 32. Each, or any, array 30 of the stack could have its rows 90 of LEDs 32 arranged differently, for example as shown in Figure 20c. In a variant of the arrangements shown in Figures 20a to 20c and Figure 21, supplementary LED arrays 94 could be disposed on edges of the support 96 like those shown Figures 18a and 18b. Many other variations are possible within the inventive concept. For example, LEDs of an array need not be disposed in straight rows or columns or in matrices, whether regular or otherwise. Whilst devices of the invention are configured for intraoral, in vivo use, it would also be possible to use such devices for in vitro treatment of dental implants with UVC light before implantation.

Claims

1. An intraoral device for treatment of peri-implantitis, the device comprising a head supporting an optical engine that comprises an enclosure for accommodating a dental implant in vivo and at least one light emitter configured to emit UVC light into the enclosure.

2. The device of Claim 1, wherein the enclosure encircles an aperture for surrounding the dental implant.

3. The device of Claim 2, comprising at least one shielding formation disposed between the or each light emitter and an edge of the aperture.

4. The device of any preceding claim, further comprising at least one reflector within the enclosure.

5. The device of any preceding claim, wherein the or each light emitter faces toward a central axis extending along the enclosure.

6. The device of any preceding claim, wherein the or each light emitter is curved around an axis of curvature extending along the enclosure.

7. The device of any preceding claim, comprising two or more light emitters angularly spaced around the enclosure.

8. The device of Claim 7 when dependent on Claim 2, wherein the light emitters are angularly spaced around an axis or axes extending through the aperture.

9. The device of Claim 7 or Claim 8, comprising at least one jaw that is movable to open and close the enclosure, at least one of the light emitters being mounted on the or each jaw.

10. The device of Claim 9, wherein the or each jaw is movable relative to a housing and at least one of the light emitters is fixed relative to the housing.

11. The device of any preceding claim, wherein the or each light emitter is configured to emit UVC light at a wavelength in a range from 170 nm to 280 nm.

12. The device of any preceding claim, wherein the or each light emitter extends across a flexible substrate.

13. The device of any of Claims 1 to 11, wherein the or each light emitter extends across a substantially rigid substrate.

14. The device of any preceding claim, wherein the or each light emitter comprises an LED array.

15. The device of Claim 14, wherein the LED array comprises high-wavelength LEDs configured to emit UVC light at a relatively high wavelength and low-wavelength LEDs configured to emit UVC light at a relatively low wavelength.

16. The device of Claim 15, wherein the or each light emitter comprises at least one supplementary array at an edge of the LED array, the supplementary array comprising low-wavelength LEDs additional to those of the LED array.

17. The device of Claim 16, wherein the LEDs of the supplementary array are oriented substantially orthogonally to those of the LED array.

18. The device of any of Claims 15 to 17, wherein the low-wavelength LEDs are configured to emit UVC light at a wavelength of 260 nm or less.

19. The device of Claim 18, wherein the low-wavelength LEDs are configured to emit UVC light at a wavelength of 240 nm or less.

20. The device of any of Claims 15 to 19, wherein the low-wavelength LEDs and high-wavelength LEDs of the LED array are separated into respective groups.

21. The device of Claim 20, wherein the low-wavelength LEDs and high-wavelength LEDs of the LED array are grouped into respective rows.

22. The device of any of Claims 15 to 21, wherein the low-wavelength LEDs and high-wavelength LEDs are disposed in mutual alternation across the LED array.

23. The device of any of Claims 1 to 13, wherein the or each light emitter comprises an optical waveguide.

24. The device of Claim 23, further comprising at least one light source edge-coupled to the waveguide.

25. The device of Claim 24, further comprising an optical amplifier interposed between the or each light source and the waveguide.

26. The device of Claim 24 or Claim 25, comprising two or more light sources coupled to respective edges of the waveguide.

27. The device of Claim 26, wherein the light sources are configured to emit UVC light at respectively different wavelengths.

28. The device of any of Claims 23 to 27, wherein the waveguide is curved to define an intrados and an extrados, the intrados being light-emitting and the extrados being internally-reflecting.

29. The device of any preceding claim, further comprising an electronics engine configured to drive the optical engine and to control power and / or wavelength of UVC light emitted by the optical engine.

30. The device of any preceding claim, further comprising a timer configured to monitor an exposure period of the optical engine.

31. The device of Claim 30, wherein the timer is configured to adjust the exposure period in response to power and / or wavelength settings of UVC light emitted by the optical engine.

32. A method of treating a dental implant, the method comprising:forming an enclosure around the implant; andexposing the implant to UVC light emitted into the enclosure.5 33. The method of Claim 32, comprising opening a gap in the enclosure, admitting theimplant into the enclosure through the gap, and closing the gap to close the enclosure around the implant.

34. The method of Claim 33, comprising also admitting into the enclosure a crown that 10 is fixed to the implant.

35. The method of any of Claims 32 to 34, comprising exposing the implant to UVC light around a full circumference of the implant.

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