Modular dental implant

Abstract

A modular dental implant (100) is described comprising a plurality of segments suitable to be axially joined together, including at least one base segment (105) comprising: a body (120) having a longitudinal axis (A) and two mutually opposed axial ends along said longitudinal axis (A), of which a first axial end (125) and a second axial end (130); a conical cavity (135) having an axis coincident with the longitudinal axis (A), which is formed at the first axial end (125) of the body (120) and is tapered towards the second end (130); a prismatic seat (145) formed on a bottom surface (140) of said conical cavity (135); a conical shank (155) coaxial to and conjugated with the conical cavity (135), which protrudes from the second axial end (130) of the body (120) and is tapered away from it; and a prismatic prominence (165) having a conjugated shape to the prismatic seat (145) and protruding from a bottom surface (160) of the conical shank (155).

Description

[0001] MODULAR DENTAL IMPLANT

[0002] Technical Field

[0003] The present invention relates to a modular dental implant for fixing dentures.

[0004] Background

[0005] As is well known, dental implants are used in dentistry to implant dentures to permanently or semi-permanently replace natural teeth.

[0006] Normally, a dental implant comprises a support body, basically shaped like a screw, which is screwed into the jawbone, and an attachment body, commonly called an abutment, which is attached to the support body and which carries the artificial tooth (or more generally the denture).

[0007] Starting from this general outline, there is a wide range of dental implants that can have very different characteristics, e.g. in terms of shape (cylindrical or conical), diameter, length, thread characteristics, etc.

[0008] In this way, the dentist can choose the type of dental implant best suited to the patient's clinical picture, e.g. based on the size and condition of the bone into which the dental implant is expected to be screwed.

[0009] However, this solution means that manufacturers have to manufacture many different dental implants or the dentist is constrained to choose from a limited range.

[0010] To at least partially mitigate these drawbacks, modular dental implants have been proposed, which consist of a plurality of standard segments that can be joined axially to one another to form the final dental implant.

[0011] In this way, while providing a limited number of different standard segments, it is advantageously possible to assemble them in different quantities and / or types, effectively producing a customised dental implant according to the requirements of each dentist.

[0012] Another advantage of these modular implants is that they allow the removal of the upper segments (i.e. those screwed less deeply into the bone, i.e. closer to the gum), if they have to be replaced due to oral pathologies such as peri-implantitis.

[0013] An example of a modular dental implant is described in international patent application WO201 0 / 010558.

[0014] In the solution proposed in the aforementioned patent application, the various segments are joined together by a threaded connection.

[0015] Specifically, each segment has a threaded shank and a threaded seat, such that the threaded shank of one segment can be screwed into the threaded seat of the adjoining segment.

[0016] However, the fact that the segments are screwed together introduces a number of drawbacks, which manifest themselves both during assembly and disassembly of the dental implant.

[0017] As far as assembly is concerned, it is very complicated for the dentist to be able to screw the various segments of the dental implant together, guaranteeing sterility.

[0018] Therefore, these dental implants are not assembled directly by the dentist, but are ordered from the manufacturer according to the chosen configuration and then supplied to the applicant in a pre-assembled configuration, which drastically reduces the flexibility of the system.

[0019] During disassembly, on the other hand, for example when a dentist wishes to remove the upper segment of the dental implant, he / she will have to apply an unscrewing torque to this segment which may be transmitted, at least in part, also to the other segments connected to it, with the risk that the entire dental implant will tend to unscrew from the bone in which it is grafted, jeopardising its overall stability.

[0020] A special tool, shaped like a sort of screw, is also used to remove the various segments. It is inserted into an internal cavity of the dental implant, screwing into a threaded through- hole made in the segment to be removed.

[0021] In this way, rotating the tool (which remains axially stationary) also pulls the segment to be removed into rotation, unscrewing it.

[0022] In addition to the problems already mentioned, however, this solution implies that the segments of the dental implant are internally hollow, reducing the mechanical strength of the dental implant, which must therefore be relatively large.

[0023] In addition, the absence of appropriate tight coupling systems increases the risk of providing favourable zones for bacterial proliferation.

[0024] Disclosure of the invention

[0025] In the light of the foregoing, an object of the present invention is to solve or however mitigate the aforementioned drawbacks of the prior art, in the context of a simple, rational and relatively low-cost solution.

[0026] This and other objects are reached by the characteristics of the invention as set forth in the independent claims. The dependent claims outline preferred and / or particularly advantageous aspects of the invention which however are not strictly required for the implementation thereof.

[0027] In particular, an embodiment of the present invention provides a modular dental implant comprising a plurality of segments capable of being axially joined together, at least one basic segment of which comprises:

[0028] - a body having a longitudinal axis and two mutually opposing axial ends along said longitudinal axis, of which a first axial end and a second axial end,

[0029] - a conical cavity having an axis coincident with the longitudinal axis, which is recessed (hollowed out) at the first axial end of the body and tapered towards the second end,

[0030] - a prismatic seat on a bottom surface of said conical cavity,

[0031] - a conical shank coaxial to and having a conjugated shape to the conical cavity, which protrudes from the second axial end of the body and is tapered away from it, and

[0032] - a prismatic prominence having conjugated shape to the prismatic seat and protruding from a bottom surface of the conical shank.

[0033] With this solution, it is advantageously possible to create a dental implant by simply coupling one or more base segments together and / or with other segments, which will be detailed below.

[0034] Specifically, this coupling is achieved by axially inserting the conical shank and prismatic prominence of one segment into the conical cavity and the prismatic lowering of another segment, without the need to apply forces or clamping movements to the segments.

[0035] In fact, the conical coupling between the shank and the seat is sufficient to ensure that the segments are centred and axially referenced, while the prismatic coupling between the prominence and the lowering is sufficient to ensure that the segments are integral in rotation.

[0036] Performing these steps under sterile conditions is quite simple, to the point that the entire assembly operation can be performed directly by a dentist.

[0037] This means that the various segments of the system can be supplied loose to the dentist, who can select the combination that suits him / her best and proceed immediately with the assembly, without having to manage orders or wait to receive the finished implant from the manufacturer. After assembly, the segments of the dental implant of the present invention are also interpenetrated into each other, dramatically reducing internal voids, so that the dental implant obtained is stronger or, with the same mechanical characteristics, smaller in size than known modular dental implants.

[0038] According to a preferred aspect of the invention, the side surfaces of the conical cavity and the conical shank of the base segment can have generatrices inclined with respect to the longitudinal axis by an angle less than or equal to 5 sexagesimal degrees.

[0039] In this way, between the conical cavity of one segment and the conical shank of another segment, a so-called Morse taper coupling is created, which not only allows effective centring and axial reference of the segments, but also tends to fit them into each other, counteracting rotation and especially reciprocal axial displacement.

[0040] Another aspect of the invention provides that the prismatic seat of the base segment may have a cross-section in the shape of an irregular polygon.

[0041] Thanks to this solution, the coupling between the prismatic seat of one segment and the prismatic prominence of another segment can only take place in one mutual angular position (with respect to the longitudinal axis), thus ensuring that, when such a coupling is achieved, these two segments are properly oriented towards each other, especially in the case of externally threaded segments as will be specified later.

[0042] According to another aspect of the invention, the base segment may comprise a through- hole, preferably threaded, which is arranged coaxially with the conical cavity.

[0043] This through-hole can be useful for keeping the base segment axially joined to the other segments of the dental implant.

[0044] In this regard, an aspect of the invention provides that the modular dental implant may comprise a locking screw having a threaded stem capable of engaging (e.g., threading or screwing) in said through-hole of said base segment and a head located at one end of said threaded stem and having a diameter greater than the diameter of the through-hole. In this way, the locking screw can act as a tie rod and prevent two or more segments of the dental implant from pulling away from each other in an axial direction.

[0045] According to another aspect of the invention, the base segment can also comprise a threaded hole coaxial with the conical cavity, which is formed on a bottom surface of the prismatic seat and can have a larger diameter than the diameter of the aforesaid through- hole. This threaded hole can be useful for the attachment of an attachment segment (abutment) for dentures and for other purposes that will become clear later.

[0046] Another aspect of the invention provides that the base segment can further comprise:

[0047] - an annular prominence, coaxial with the conical cavity and protruding from the first end of the body, and

[0048] - an annular channel, having a conjugated shape to the annular prominence, which is coaxial with the conical shank and is hollowed out (recessed) at the second end of the body.

[0049] Thanks to this solution, when two segments are coupled together, the annular prominence of one fits into the annular channel of the other, improving the stability of the parts and creating a kind of labyrinth that counteracts the possible infiltration of bacteria.

[0050] According to another aspect of the invention, the base segment can comprise a helical thread, which is made on an outer side surface of the body.

[0051] Thus, after being assembled with other segments to form the dental implant, the base segment is particularly suitable for screwing into a bone.

[0052] In addition to one or more of the base segments outlined above, the segments of the modular dental implant may further comprise at least one tip segment comprising:

[0053] - a body having a longitudinal axis and two mutually opposed axial ends along said longitudinal axis, of which a first axial end and a second axial end,

[0054] - a conical cavity having an axis coincident with the longitudinal axis and a conjugate shape with the conical shank of the base segment, which is formed (hollowed out) at the first axial end of the body and tapered towards the second end, and

[0055] - a prismatic seat formed on a bottom surface of said conical cavity and having a conjugate shape to the prismatic prominence of the base segment.

[0056] This tip segment is advantageously suited to be used as the end of the dental implant, opposite to that in which the actual denture will be placed.

[0057] In particular, this tip segment can be coupled to an immediately adjoining base segment by simply inserting the conical shank and prismatic prominence of the latter into the conical cavity and prismatic seat of the tip segment.

[0058] Being a tip segment, it is not necessary for it to comprise in turn a conical shank and / or prismatic prominence at the second end of the body.

[0059] In contrast, a preferred aspect of the invention is that the second axial end of the body of the tip segment may be flat and orthogonal to the longitudinal axis, not excluding other geometric shapes that may favour screwing into the bone during surgery.

[0060] According to an aspect of the invention, the tip segment can also comprise a threaded hole coaxial with the conical cavity and formed on a bottom surface of the prismatic seat. This threaded hole can be useful for keeping the tip segment axially joined to the other segments of the dental implant.

[0061] For example, this threaded hole may be adapted to receive the free end of the previously mentioned locking screw in screwing.

[0062] Another aspect of the invention is that the tip segment may also comprise:

[0063] - an annular prominence, having a conjugated shape to the annular channel of the base segment, which is coaxial with the conical cavity and protrudes from the first axial end of the body.

[0064] In this way, the annular prominence of the tip segment can be coupled with the annular channel of the adjoining base segment, improving the stability of the parts and creating a kind of labyrinth that counteracts the possible infiltration of bacteria.

[0065] According to another aspect of the invention, the tip segment can also comprise a helical thread, which is made on an outer side surface of its body.

[0066] Thus, after being assembled with other segments to form the dental implant, the tip segment is particularly suitable for screwing into a bone.

[0067] Another aspect of the invention is that the dental implant may comprise a protective cap comprising:

[0068] - a conical shank having a longitudinal axis and conjugated shape to the conical cavity of the base segment,

[0069] - a head placed at an axial end of the conical shank and having a radial extension greater than it,

[0070] - and a stem placed at the opposite axial end of the conical shank and having at least one threaded portion suitable for screwing into the threaded hole in the bottom surface of the prismatic seat of the base segment.

[0071] This protective cap can be used in the post-operative phase to temporarily close the conical cavity of the base body proximal to the gingiva and to prevent any kind of infiltration into the implant as a result of the temporary closure of the gingiva itself.

[0072] According to a preferred aspect of the invention the conical shank of the protective cap has an axial extension less than the axial extension of the conical cavity of the base segment, for example less than half the axial extension of the conical cavity of the base segment.

[0073] In this way, the coupling between the conical shank of the protective cap and the conical cavity of the base segment does not offer too much resistance when screwing and unscrewing the cap.

[0074] According to another aspect of the invention, the protective cap may further comprise:

[0075] - an annular channel, having a conjugated shape to the annular prominence of the base segment, which is coaxial to the conical shank and is formed on a surface of the head from which the conical shank itself protrudes.

[0076] In this way, the annular channel of the protective cap can be coupled with the annular prominence of the base segment to which the protective cap is applied, improving the stability of the parts and creating a kind of labyrinth that counteracts the possible infiltration of bacteria.

[0077] Another aspect of the invention provides that modular dental implant segments may further comprise a denture attachment segment (also called an abutment) comprising:

[0078] - a body having a longitudinal axis and two mutually opposing axial ends along said longitudinal axis, of which a first axial end and a second axial end,

[0079] - a conical shank having an axis coincident with the longitudinal axis and a conjugated shape to the conical cavity of the base segment, which protrudes from the second axial end of the body and is tapered away from it, and

[0080] - a prismatic prominence projecting from a bottom surface of the conical shank and fitting into the prismatic seat of the base segment.

[0081] This attachment segment is advantageously suitable for use as a support for the denture (e.g. artificial tooth).

[0082] For example, the denture can be made directly on this attachment segment.

[0083] The attachment segment can be coupled to an immediately adjacent base segment, e.g. after removing the protective cap mentioned above, by simply inserting the conical shank and prismatic prominence of the attachment segment into the conical cavity and prismatic seat of said base segment.

[0084] According to an aspect of the invention, the attachment segment may comprise a through- hole having an axis coincident with the longitudinal axis. This through-hole can be useful for axially locking the attachment segment (and thus the denture) to the other segments of the dental implant.

[0085] In this regard, an aspect of the invention provides that the dental implant may comprise a locking element having a cylindrical stem suitable to be inserted into the through-hole of the attachment segment, a head having a diameter greater than the through-hole and located at an axial end of the cylindrical stem and a threaded shank placed at the opposite axial end of the cylindrical stem and suitable to be screwed into the threaded hole in the bottom surface of the prismatic seat of the base segment.

[0086] In this context, a preferred aspect of the invention is that the attachment segment may comprise a lowering suitable to accommodate the head of the locking element.

[0087] Another aspect of the invention provides that said through-hole of the attachment segment may comprise at least one threaded portion.

[0088] This threaded portion of the through-hole can advantageously be used for coupling with a tool suitable to allow the attachment segment to be removed from the dental implant.

[0089] According to another aspect of the invention, the attachment segment can also comprise:

[0090] - an annular channel, having a conjugated shape to the annular prominence of the base segment, which is formed at the second end of the body and is coaxial with the conical shank.

[0091] In this way, the annular channel of the attachment segment can be coupled with the annular prominence of the base segment adjacent to it, improving the stability of the parts and creating a kind of labyrinth that counteracts the possible infiltration of bacteria.

[0092] Another embodiment of the present invention makes available an assembly kit for the modular dental implant outlined above, which comprises:

[0093] - a first tool having a stem with a central through-hole and a prismatic prominence projecting from an axial end of said stem and suitable to be inserted into the prismatic seat of the base segment, and

[0094] - a second tool having a stem suitable to be slidably and rotatably inserted into the central hole of the first tool, in which a free end of said stem is shaped to form a prismatic coupling with the head of the locking screw.

[0095] This assembly kit facilitates the assembly of the various segments that will form the dental implant, as well as its screwing into the patient's bone.

[0096] Another embodiment of the present invention finally makes available a disassembly kit for the modular dental implant outlined above, which comprises:

[0097] - a rod with a smooth portion and a threaded portion suitable to be engaged in the through-hole of the base segment,

[0098] - a first tool having a stem provided with a central through-hole and a threaded shank made at an axial end of said stem suitable to be screwed into the threaded hole of the base segment, and

[0099] - a second tool having a stem suitable to be slidably and rotatably inserted into the central hole of the first tool, wherein a free end of said stem is suitable for forming a prismatic coupling with a free end of the smooth portion of the rod.

[0100] This kit makes it advantageously possible to remove, for example but not exclusively in the case of oral pathologies such as peri-implantitis, a segment of the dental implant, typically the one placed more on the surface (i.e. closer to the gum), without the risk of jeopardising the anchorage of the other implant segments to the patient's bone.

[0101] Brief description of the drawings

[0102] Further features and advantages of the invention will be more apparent after reading the following description provided by way of non-limiting example, with the aid of the accompanying drawings.

[0103] Figure 1 is a side view of a base segment of a modular dental implant according to an embodiment of the present invention.

[0104] Figure 2 is a bottom view of the base segment of figure 1 .

[0105] Figure 3 is a top view of the base segment of figure 1 .

[0106] Figure 4 is the section IV-IV indicated in figure 1 .

[0107] Figure 5 is a side view of a tip segment of a modular dental implant according to an embodiment of the present invention.

[0108] Figure 6 is a bottom view of the tip segment of figure 5.

[0109] Figure 7 is a top view of the tip segment of figure 5.

[0110] Figure 8 is the section VIII-VIII indicated in figure 5.

[0111] Figure 9 is a side view of an attachment segment of a modular dental implant according to an embodiment of the present invention.

[0112] Figure 10 is a bottom view of the attachment segment of figure 9.

[0113] Figure 1 1 is a top view of the attachment segment of figure 9.

[0114] Figure 12 is the section XII-XII indicated in figure 9. Figure 13 is a side view of a modular dental implant according to an embodiment of the present invention.

[0115] Figure 14 is the section XIV-XIV indicated in figure 13.

[0116] Figure 15 is a side view of the assembly formed by the base and tip segments of the dental implant of figure 13.

[0117] Figure 16 is the section XVI-XVI indicated in figure 15.

[0118] Figure 17 is an exploded perspective elevation view of the assembly of figure 15.

[0119] Figure 18 is a side view of a first tool of an assembly kit of the dental implant.

[0120] Figure 19 is the section XIX-XIX indicated in figure 18.

[0121] Figure 20 is a bottom view of the first tool of figure 17.

[0122] Figure 21 is a side view of the second tool of the dental assembly kit of the dental implant.

[0123] Figure 22 is a bottom view of the second tool of figure 21 .

[0124] Figure 23 is section XXI I l-XXI 11 of figure 21 .

[0125] Figure 24 is a side view of the coupling of the assembly of figure 15 with the assembly kit.

[0126] Figure 25 is the section XXV-XXV indicated in figure 24.

[0127] Figure 26 is an enlarged detail of figure 25.

[0128] Figure 27 is a side view of a protection cap of the modular dental implant according to an embodiment of the present invention.

[0129] Figure 28 is a bottom view of the cap of figure 27.

[0130] Figure 29 is a top view of the cap of figure 27.

[0131] Figure 30 is the section XXX-XXX indicated in figure 27.

[0132] Figure 31 is a side view of the assembly of figure 15 with the cap of figure 27.

[0133] Figure 32 is section XXXII-XXXII of figure 31 .

[0134] Figure 33 is a side view of a first tool of a disassembly kit of the dental implant .

[0135] Figure 34 is section XXXIV-XXXIV of figure 33.

[0136] Figure 35 is a side view of a rod of the dental implant disassembly kit.

[0137] Figure 36 is a side view of the coupling of the assembly of figure 15 with the disassembly kit.

[0138] Figure 37 is the section XXXVII-XXXVII indicated in figure 36.

[0139] Figure 38 is an enlarged detail of figure 36.

[0140] Figure 39 is a side view of a base segment of a modular dental implant according to a variant.

[0141] Figure 40 is a bottom view of the base segment of Figure 39.

[0142] Figure 41 is a top view of the base segment of figure 39.

[0143] Figure 42 is the XLII-XLII section indicated in figure 39.

[0144] Figure 43 is a side view of a modular dental implant made with base segments according to the variant of figure 39.

[0145] Figure 44 is the XLIV-XLIV section indicated in figure 43.

[0146] Detailed description

[0147] A system for the manufacturing of modular dental implants 100 is described with the help of the above-mentioned figures.

[0148] This system makes use of a plurality of segments that are made separately and independently of each other, preferably of titanium, and that are then joined axially to each other, preferably by means of a dismountable fixing system, in order to make the final dental implant 100.

[0149] In the example shown, the system can make use of three types of segments, one type of base segment 105, one type of tip segment 1 10, and one type of attachment segment 1 15 (also known as abutments).

[0150] As illustrated in figures 1 to 4, each base segment 105 may comprise a body 120 having a longitudinal axis A and two mutually opposed axial ends along said longitudinal axis A, of which a first axial end 125 and a second axial end 130.

[0151] Not counting possible threads and / or other possible surface elements discussed below, the body 120 can generally have the shape of a rotational solid, e.g. cylindrical or conical, whose axis coincides with the aforementioned longitudinal axis A.

[0152] In this case, the body 120 has an at least slightly conical shape that narrows from the first axial end 125 towards the second axial end 130.

[0153] However, the specific shape and size of the body 120 of each base segment 105 may vary depending on the type and the position it is to occupy within the dental implant 100. Each base segment 105 may also comprise a conical cavity 135, which is formed in the body 120 and extends from the first axial end 125 towards the second axial end 130.

[0154] The conical cavity 135 has an axis coincident with the longitudinal axis A and is tapered from the first axial end 125 towards the second axial end 130.

[0155] Preferably, the side surface of the conical cavity 135 has generatrices whose inclination, with respect to the longitudinal axis A, is less than or equal to 5 sexagesimal degrees.

[0156] The conical cavity 135 may terminate with a bottom surface 140, preferably flat and orthogonal to the longitudinal axis A.

[0157] The conical cavity 135 is preferably identical for all the base segments 105 of the system. Each base segment 105 may further comprise a prismatic seat 145, which is formed on said bottom surface 140 and extends towards the second axial end 130 of the body 120. This prismatic seat 145 may have a constant cross-sectional area for its entire height, i.e. a cross-section of the same shape and dimensions for any cross-sectional plane orthogonal to the longitudinal axis A.

[0158] In particular, this cross-section may have the shape of a polygon, preferably one whose vertices are all aligned on a circumference centred on the longitudinal axis A.

[0159] This circumference may have a diameter less than or equal to the diameter of the crosssection of the conical cavity 135 at the bottom surface 140 on which the prismatic seat 145 is located.

[0160] In particular, for reasons that will become clearer later, it may be preferable for the crosssection of the prismatic seat 145 to have the shape of an irregular polygon.

[0161] For example, in the embodiment illustrated in the figures, the cross-section of the prismatic seat 145 has the shape of a heptagon, which is, however, formed by five consecutive sides of a regular hexagon, the sixth side of which is subdivided into two smaller sides, preferably of equal length, defining a common vertex that lies on the same circumference as all the other vertices of the polygon.

[0162] The prismatic seat 145 is preferably identical for all the base segments 105 of the system. The bottom of the prismatic seat 145 can be defined by a flat surface 150 orthogonal to the longitudinal axis A.

[0163] Each base segment 105 may further comprise a conical shank 155, which protrudes from the second axial end 130 of the body 120 and is tapered in order to narrow away from it. This conical shank 155 is placed coaxial with the conical cavity 135 and may terminate, for example, with a flat bottom surface 160 orthogonal to the longitudinal axis A.

[0164] Specifically, the conical shank 155 may have a conjugated or complementary shape to that of the conical cavity 135.

[0165] A conjugated or complementary shape means that at least one strip of the conical shank 155, preferably the entire conical shank 155, has the same shape and dimensions, in negative, as a corresponding strip of the conical cavity 135, preferably the entire conical cavity 135.

[0166] Thus, for example, the generatrices of the side surface of the conical shank 155 may be inclined with respect to the longitudinal axis A by the same angle (e.g. less than or equal to 5 sexagesimal degrees) as the generatrices of the side surface of the conical cavity 135.

[0167] The cross-sectional area of the conical shank 155, at the second axial end 130 of the body 120, may have the same diameter as the cross-sectional area of the conical cavity 135, at the first axial end 125 of the body 120.

[0168] The height of the conical shank 155, i.e. the axial distance between the second axial end 130 and the bottom surface 160, may be equal to the depth of the conical cavity 135, i.e. the axial distance between the first axial end 125 and the bottom surface 140.

[0169] The conical shank 155 is preferably identical for all the base segments 105 forming the system.

[0170] Each base segment 105 may further comprise a prismatic prominence 165, which protrudes from the bottom surface 160 of the conical shank 155 and may terminate with a head surface 170, preferably flat and orthogonal to the longitudinal axis A.

[0171] This prismatic prominence 165 may have a constant cross-sectional area for its entire height, i.e. a cross-section of the same shape and dimensions for any cross-sectional plane orthogonal to the longitudinal axis A.

[0172] This cross-section may have the shape of a polygon, preferably an irregular one, whose vertices are all aligned on a circumference centred on the longitudinal axis A.

[0173] This circumference may have a diameter less than or equal to the diameter of the crosssection of the conical shank 155 at the bottom surface 160 from which the prismatic prominence 165 protrudes.

[0174] In particular, the prismatic prominence 165 may have a conjugated or complementary shape to the prismatic seat 145.

[0175] Again, a conjugated or complementary shape means that at least one strip of the prismatic prominence 165, preferably the entire prismatic prominence 165, has the same shape and dimensions, in negative, as a corresponding strip of the prismatic seat 145, preferably the entire prismatic seat 145.

[0176] Thus, for example, the cross-section of the prismatic prominence 165 may have the same heptagonal shape and dimensions as the cross-section of the prismatic seat 145.

[0177] The prismatic prominence 165 is preferably identical for all the base segments 105 forming the system.

[0178] Each base segment 105 may further comprise a threaded hole 175, which is formed on the surface 150 defining the bottom of the prismatic seat 145 and extending towards the conical shank 155.

[0179] This threaded hole 175 can be arranged coaxially with the conical cavity 135 and, consequently, also with the conical shank 155, and can have a diameter smaller than the largest circumference that can be inscribed in the cross-section of the prismatic seat 145.

[0180] The diameter and thread of the threaded hole 175 are preferably identical for all the base segments 105 forming the system.

[0181] Each base segment 105 may also comprise a through-hole 180, which is also coaxial with the conical cavity 135 and may have a smaller diameter than the threaded hole 175. In particular, this through-hole 180 may start from the bottom of the threaded hole 175 and finish at the head end 170 of the prismatic prominence 165.

[0182] The through-hole 180 is also preferably threaded, although its thread may be different from that of the threaded hole 175.

[0183] The diameter and thread of the through-hole 180 are preferably identical for all base segments 105 forming the system.

[0184] In addition, each base segment 105 may comprise an annular prominence 185, which protrudes from the first axial end 125 of the body 120, extending from the opposite side to the second axial end 130.

[0185] This annular prominence 185 may be coaxial with the conical cavity 135 and may encircle its mouth, i.e. it may encircle the cross-section of the conical cavity 135 located at the first axial end 125 of the body 120.

[0186] At the second axial end 130 of the body 120, each base segment 105 may comprise an annular channel 190, which is arranged coaxially and surrounds the base of the conical shank 155, i.e. it surrounds the cross-section of the conical shank 155 located at the second end 130 of the body 120.

[0187] The annular channel 190 may have a conjugated or complementary shape to the annular prominence 185.

[0188] Again, a conjugated or complementary shape means that at least one strip of the annular channel 190, preferably the entire annular channel 190, has the same shape and dimensions, in negative, as a corresponding strip of the annular prominence 185, preferably the inner annular prominence 185.

[0189] The annular prominence 185 and annular channel 190 are preferably identical for all the base segments 105 forming the system.

[0190] Each base segment 105 may finally comprise a helical thread 195, or more properly a portion of a helical thread, which has a helix axis coincident with the longitudinal axis A and is made on the side surface of the body 120.

[0191] The shape and other characteristics of this helical thread 195 may vary from one base segment 105 to another.

[0192] Turning to the tip segments 110, they have many aspects in common with the base segments 105, from which they differ mainly in that they do not include the conical shank 155 and the prismatic prominence 165.

[0193] More specifically, as illustrated in figures 5 to 8, each tip segment 110 may comprise a body 200 having a longitudinal axis B and two mutually opposed axial ends along said longitudinal axis B, of which a first axial end 205 and a second axial end 210.

[0194] Not counting possible threads and / or other possible surface elements discussed below, the body 200 can generally have the shape of a rotational solid, e.g. cylindrical or conical, whose axis coincides with the aforementioned longitudinal axis B.

[0195] In this case, the body 200 has an at least slightly conical shape that narrows from the first axial end 205 towards the second axial end 210.

[0196] The second axial end 210 of the body 200 may be at least slightly convex or rounded, without however excluding that it may have any other shape, either tapered or possibly flat and orthogonal to the longitudinal axis B.

[0197] However, the specific shape and dimensions of the 200 body may vary between one tip segment 1 10 and another.

[0198] The tip segment 1 10 may further comprise a conical cavity 215, having an axis coincident with the longitudinal axis B, which is formed at the first axial end 205 of the body 200 and is tapered so as to narrow towards the second end 210.

[0199] The conical cavity 215 may terminate with a bottom surface 220, preferably flat and orthogonal to the longitudinal axis B.

[0200] The conical cavity 215 may have a conjugated or complementary shape to the conical shank 155 of the base segments 105.

[0201] A conjugated or complementary shape means that at least one strip of the conical cavity 215, preferably the entire conical cavity 215, has the same shape and dimensions, in negative, as a corresponding strip of the conical shank 155 of the base segments 105, preferably the entire conical shank 155.

[0202] Thus, for example, the generatrices of the side surface of the conical cavity 215 may be inclined, with respect to the longitudinal axis B, by the same angle (e.g. less than or equal to 5 sexagesimal degrees) as the generatrices of the side surface of the conical shank 155.

[0203] The cross-sectional area of the conical cavity 215, at the first axial end 205 of the body 200, may have the same diameter as the cross-sectional area of the conical shank 155, at the second axial end 130 of the body 120.

[0204] The depth of the conical cavity 215, i.e. the axial distance between the first axial end 205 of the body 200 and the bottom surface 220, may be equal to the height of the conical shank 155, i.e. the axial distance between the second axial end 130 of the body 120 and the bottom surface 160.

[0205] In practice, the conical cavity 215 of the tip segment 1 10 may be identical to the conical cavity 135 of the base segments 105.

[0206] The tip segment 1 10 may also include a prismatic seat 225 that is formed on the bottom surface 220 of the conical cavity 215 and protrudes towards the second axial end 210 of the body 200.

[0207] This prismatic seat 225 may have a constant cross-sectional area for its entire height, i.e. a cross-section of the same shape and dimensions for any cross-sectional plane orthogonal to the longitudinal axis B.

[0208] In particular, this cross-section may have the shape of a polygon, preferably one whose vertices are all aligned on a circumference centred on the longitudinal axis B.

[0209] This circumference may have a diameter less than or equal to the diameter of the crosssection of the conical cavity 215 at the bottom surface 220 on which the prismatic seat 225 is located.

[0210] In particular, the prismatic seat 225 may be conjugated or complementary to the prismatic prominence 165 of the base segments 105.

[0211] Again, a conjugated or complementary shape means that at least one strip of the prismatic seat 225, preferably the entire prismatic seat 225, has the same shape and dimensions, in negative, as a corresponding strip of the prismatic prominence 165, preferably the entire prismatic prominence 165.

[0212] Thus, for example, the cross-section of the prismatic seat 225 may have the same heptagonal shape and dimensions as the cross-section of prismatic prominence 165.

[0213] In practice, the prismatic seat 225 of the tip segment 1 10 may be identical to the prismatic seat 145 of the base segments 105.

[0214] The bottom of the prismatic seat 225 can be defined by a flat surface 230 orthogonal to the longitudinal axis B.

[0215] The tip segment 110 may further comprise a threaded hole 235 coaxial with the conical cavity 215, which may be formed on the surface 230 defining the bottom of the prismatic seat 225, extending towards the second axial end 210 of the body 200.

[0216] This threaded hole 235 may be a blind hole and may have a diameter smaller than the maximum circumference that can be inscribed in the cross-section of the prismatic seat 225.

[0217] The diameter and thread of the threaded hole 235 are preferably identical to those of the through-hole 180 of the base segments 105.

[0218] The tip segment 1 10 may then comprise an annular prominence 240, which protrudes from the first axial end 205 of the body 200, projecting from the opposite side to the second axial end 210.

[0219] This annular prominence 240 may be coaxial with the conical cavity 215 and may encircle its mouth, i.e. it may encircle the cross-section of the conical cavity 215 located at the first axial end 205 of the body 200.

[0220] The annular prominence 240 may have a conjugated or complementary shape to the annular channel 190 of the base segments 105.

[0221] Again, a conjugated or complementary shape means that at least one strip of the annular prominence 240, preferably the entire annular prominence 240, has the same shape and dimensions, in negative, as a corresponding strip of the annular channel 190, preferably the inner annular channel 190.

[0222] In practice, the annular prominence 240 of the tip segment 1 10 may be identical to the annular prominence 185 of the base segments 105.

[0223] Finally, the tip segment 1 10 may comprise a helical thread 245, or more properly a portion of a helical thread, which has a helix axis coincident with the longitudinal axis B and is made on the side surface of the body 200.

[0224] The shape and other characteristics of this helical thread 245 may differ from those of the threads 195 of the base segments 105.

[0225] Turning to the attachment segments 1 15, they serve as support for the denture (e.g. artificial tooth).

[0226] As illustrated in figures 9 to 12, each attachment segment 1 15 may comprise a body 250 having a longitudinal axis C and two mutually opposed axial ends along said longitudinal axis C, a first axial end 255 and a second axial end 260.

[0227] The denture (not illustrated) may be directly made or threaded onto body 250 of attachment segment 1 15, which may be of any shape suitable for the purpose.

[0228] The attachment segment 1 15 may further comprise a conical shank 265, which protrudes from the second axial end 260 of the body 250 and is tapered in order to narrow away from it.

[0229] This conical shank 265 can end, for example, with a flat bottom surface 270 orthogonal to the longitudinal axis C.

[0230] Specifically, the conical shank 265 may have a conjugated or complementary shape to the conical cavity 135 of each base segment 105.

[0231] A conjugated or complementary shape means that at least one strip of the conical shank 265, preferably the entire conical shank 265, has the same shape and dimensions, in negative, as a corresponding strip of the conical cavity 135, preferably the entire conical cavity 135.

[0232] Thus, for example, the generatrices of the side surface of the conical shank 265 may be inclined with respect to the longitudinal axis C by the same angle (e.g. less than or equal to 5 sexagesimal degrees) as the generatrices of the side surface of the conical cavity 135.

[0233] The cross-sectional area of the conical shank 265, at the second axial end 260 of the body 250, may have the same diameter as the cross-sectional area of the conical cavity 135, at the first axial end 125 of the body 120.

[0234] The height of the conical shank 265, i.e. the axial distance between the second axial end 260 of the body 250 and the bottom surface 270, may be equal to the depth of the conical cavity 135, i.e. the axial distance between the first axial end 125 of the body 120 and the bottom surface 140.

[0235] In practice, the conical shank 265 of the attachment segment 1 15 may be identical to the conical shank 155 of the base segments 105.

[0236] The attachment segment 1 15 may further comprise a prismatic prominence 275, which protrudes from the bottom surface 270 of the conical shank 265 and may terminate with a head surface 280, preferably flat and orthogonal to the longitudinal axis C.

[0237] This prismatic prominence 275 may have a constant cross-sectional area for its entire height, i.e. a cross-section of the same shape and dimensions for any cross-sectional plane orthogonal to the longitudinal axis C.

[0238] This cross-section may be in the shape of a polygon, regular or irregular, whose vertices are all aligned on a circumference centred on the longitudinal axis C.

[0239] This circumference may have a diameter less than or equal to the diameter of the crosssection of the conical shank 265 at the bottom surface 270 from which the prismatic prominence 275 protrudes.

[0240] In particular, the prismatic prominence 275 may be shaped to fit axially into the prismatic seat 145 of each base segment 105, to create a prismatic coupling with it.

[0241] In this case, however, it is not strictly necessary, although neither is it excluded, that the prismatic prominence 275 must have a conjugated or complementary shape to the prismatic seat 145.

[0242] For example, in the specific embodiment, in which the cross-section of prismatic seat 145 is that of an irregular heptagon obtained by splitting one side of a regular hexagon, the cross-section of the prismatic prominence 275 may be that of a regular hexagon having the same dimensions as the one on which the shape of the prismatic seat 145 is based. At the first axial end 255 of the body 250, each attachment segment 1 15 may comprise a lowering 281 , preferably cylindrical or disc shaped with an axis coincident with the longitudinal axis C.

[0243] At the second axial end 260 of the body 250, each attachment segment 1 15 may comprise an annular channel 285, which is arranged coaxially and surrounds the base of the conical shank 265, i.e. it surrounds the cross-section of the conical shank 265 located at the second end 260 of the body 250.

[0244] The annular channel 285 may have a conjugated or complementary shape to the annular prominence 185 of base segments 105. Again, a conjugated or complementary shape means that at least one strip of the annular channel 285, preferably the entire annular channel 285, has the same shape and dimensions, in negative, as a corresponding strip of the annular prominence 185, preferably the inner annular prominence 185.

[0245] Each attachment segment 1 15 may also include a through-hole 290 having an axis coincident with the longitudinal axis C.

[0246] For reasons that will become clear later, this through-hole 290 may have a diameter comprised between the diameter of the threaded hole 175 and the diameter of the largest circumference that can be inscribed in the cross-section of the prismatic seat 145 of the base segments 105.

[0247] The through-hole 290 may extend from the bottom surface of the lowering 281 (if present), or in any case from the first axial end 255 of the body 250, to the top surface 280 of the prismatic prominence 275.

[0248] At least one portion 291 of the through-hole 290, preferably the portion proximal to the first end 255 of the body 250, may be internally threaded.

[0249] Using segments of one or more of the types outlined above, it is advantageously possible to assemble a plurality of dental implants 100 with different characteristics.

[0250] For example, the dental implant 100 illustrated in figures 13 and 14 comprises two base segments 105 interposed between an attachment segment 1 15 and a tip segment 1 10.

[0251] As can be seen, the body 120 of base segment 105 proximal to the tip segment 1 10 may be narrower and longer than body 120 of base segment 105 proximal to the attachment segment 1 15.

[0252] In addition, the helical thread 195 of the base segment 105 close to the tip segment 1 10 may generally be thinner and thus sharper than the helical thread 195 of the base segment 105 proximal to the attachment segment 1 15.

[0253] As illustrated in figures 15 to 17, the base segments 105 are assembled together simply by axially inserting the conical shank 155 of one into the conical cavity 135 of the other, taking care that the prismatic prominence 165 protruding from the conical shank 155 of the former is in turn inserted into the prismatic seat 145 formed on the bottom of the conical cavity 135 of the latter.

[0254] In this way, the conical coupling made between the conical shank 155 and the conical seat 135 ensures centring between the two base segments 105, which are therefore perfectly coaxial.

[0255] Furthermore, if the generatrices of the side surfaces of the conical shank 155 and the conical cavity 135 are inclined at an angle equal to or less than 5 sexagesimal degrees to the longitudinal axis, it is advantageously possible to realise a so-called Morse taper coupling, i.e. an interlocking that opposes reciprocal axial rotation and slippage.

[0256] At the same time, the coupling between the prismatic prominence 165 and the prismatic seat 145 achieves a prismatic coupling between the two base segments 105, which makes them integral in rotation.

[0257] In this respect, the irregular cross-sectional area that may be conferred to the prismatic prominence 165 and the prismatic seat 145 (e.g., heptagonal as explained above) has the advantage of allowing mutual insertion only for a predetermined relative angular position between the base segments 105, which may be chosen so that the respective threads 195 are substantially the continuation of each other, without the risk of causing the occurrence of significant discontinuities.

[0258] Similarly, the tip segment 1 10 may be assembled to the base segment 105 adjacent to it, simply by axially fitting the conical cavity 215 of the tip segment 1 10 onto the conical shank 155 of the base segment 105, always taking care that the prismatic prominence 165 protruding from the conical shank 155 fits in turn into the prismatic seat 225 obtained on the bottom of the conical cavity 215.

[0259] Also in this case, the conical coupling made between the conical shank 155 and the conical cavity 215 ensures centring between the base segment 105 and the tip segment 1 10, which are therefore perfectly coaxial.

[0260] Furthermore, if the generatrices of the side surfaces of the conical shank 155 and the conical cavity 215 are inclined at an angle equal to or less than 5 sexagesimal degrees to the common longitudinal axis, it is advantageously possible to realise the Morse taper coupling that opposes reciprocal axial rotation and slippage.

[0261] At the same time, the coupling between the prismatic prominence 165 and the prismatic seat 225 achieves a prismatic coupling that makes the tip segment 110 rotationally integral to the base segment 105.

[0262] The irregular cross-section that may be conferred to the prismatic prominence 165 and the corresponding prismatic seat 225 (e.g., heptagonal as explained above) has, also in this case, the advantage of allowing the mutual insertion only for a predetermined relative angular position of the tip segment 1 10 with respect to the base segment 105, which may be chosen so that the thread 195 of the base segment 105 and the thread 245 of the tip segment 1 10 are substantially the continuation of each other, without the risk of causing the occurrence of significant discontinuities.

[0263] Although the axial constraint between the base segment 105 and the tip segment 1 10 can already be ensured by Morse taper couplings, greater security of the mutual constraint may be achieved with a locking screw 300.

[0264] This locking screw 300 may comprise a threaded stem 305 suitable to be screwed into the through-holes 180 of the base segments 105 and into the threaded hole 235 of the tip segment 1 10, as well as a head 310 placed at one end of said threaded stem 305 and having a diameter greater than the diameter of the through-holes 180, so as to rest on the bottom of the threaded hole 175 of the first base segment 105 (i.e. the one closest to the denture) and thus be capable of firmly clamping the various segments together.

[0265] In particular, the head 310 may have a flared shape designed to be wedged into a corresponding flared cavity formed at the mouth of the through-hole 180 of the first base segment 105.

[0266] Preferably, however, the diameter of the head 310 is smaller than the diameter of threaded hole 175, for reasons that will become clear later.

[0267] The locking screw 300 may also comprise an axial cavity 31 1 recessed axially from the surface of the head 310 which is on the opposite side from the threaded stem 235, and which has a pyramid (or truncated pyramid) shape, e.g. with a hexagonal base, which narrows towards the bottom.

[0268] Preferably, the faces of the pyramid defining the axial cavity 31 1 may have an inclination, with respect to the longitudinal axis of the locking screw 300, less than or equal to 5 sexagesimal degrees.

[0269] To facilitate assembly, the assembly of the base segment 105 and the tip segment 110, if any, may be carried out with the aid of an assembly kit comprising a first tool 800 and a second tool 900.

[0270] As illustrated in figures 18 to 20, the first tool 800 comprises a stem 805, which may be derived from a handle 810, shaped for example like a kind of cylinder.

[0271] The stem 805, which can have a tapered shape with a circular cross-section, has diameters such that it can fit freely into the conical cavity 135 of the base segment 105. The first tool 800 may further comprise a prismatic prominence 815, which protrudes from the free axial end of the stem 805, i.e. the end opposite the handle 810, and may terminate with a head surface 820, preferably flat and orthogonal to the longitudinal axis of the stem 805.

[0272] This prismatic prominence 815 may have a constant cross-sectional area for its entire height, i.e. a cross-section of the same shape and dimensions for any cross-sectional plane orthogonal to the longitudinal axis.

[0273] In particular, the prismatic prominence 815 may be shaped to fit axially into the prismatic seat 145 of the base segment 105, to create a prismatic coupling with it.

[0274] Also in this case, it is not strictly necessary, although neither is it excluded, that the prismatic prominence 815 must have a conjugated or complementary shape to the prismatic seat 145.

[0275] For example, in the specific embodiment, in which the cross-section of prismatic seat 145 is that of an irregular heptagon obtained by splitting one side of a regular hexagon, the cross-section of the prismatic prominence 815 may be that of a regular hexagon having the same dimensions as the one on which the shape of the prismatic seat 145 is based. The first tool 800 also includes a central through-hole 825 which passes through the stem 805, the prismatic prominence 815 and the handle 810 and which, when the prismatic prominence 815 is inserted into the prismatic seat 145, is coaxial to the through-hole 180 of the base segment 105.

[0276] The diameter of the central through-hole 825 is preferably greater than the diameter of the through-hole 180, e.g. greater than or equal to the maximum diameter of the head 310 of the locking screw 300 or, more generally, greater than or equal to the maximum diameter of the widest portion of the locking screw 300.

[0277] Turning to the second tool 900 in the assembly kit (see figures 21 to 23), it may have a stem 905 and possibly a handle 910, shaped, for example, like a plate, from which said stem 905 is derived.

[0278] The diameter of the stem 905 may be substantially the same, or at least not larger (e.g. smaller), than the diameter of the central through-hole 825 of the first tool 800, so that it may be smoothly and rotatably inserted into it.

[0279] For example, the diameter of the stem 905 may be equal to the maximum diameter of the head 310 of the locking screw 300. The free end of the stem 905 may have a prominence 915 to create a prismatic coupling with the axial cavity 31 1 of the head 310 of the locking screw 300.

[0280] In particular, this prominence 915 may have a pyramid (or truncated pyramid) shape, e.g. with a hexagonal base, which narrows away from the free end of the stem 905.

[0281] Preferably, the faces of the pyramid defining the prominence 915 may have an inclination, with respect to the longitudinal axis of the stem 905, less than or equal to 5 sexagesimal degrees.

[0282] Specifically, the prominence 915 may be conjugated or complementary to the axial cavity 31 1.

[0283] Again, a conjugated or complementary shape means that at least one strip of the prominence 915, preferably the entire prominence 915, has the same shape and dimensions, in negative, as a corresponding strip of the axial cavity 31 1 , preferably the entire axial cavity 31 1.

[0284] In this way, when a professional has to assemble an implant 100, he can first insert the first tool 800 into the first base segment 105, taking care to couple the prismatic prominence 815 into the prismatic seat 145.

[0285] Next, the locking screw 300 is taken with the second tool 900, taking care to couple the axial cavity 31 1 of the latter with the prominence 915 of the second tool.

[0286] In this way, also thanks to the inclination of the pyramid faces, the locking screw 300 will be temporarily coupled to the second tool 900 by the Morse effect and can thus be easily moved.

[0287] At this point, the locking screw 300 and the stem 905 of the second tool 900 may be inserted into the central hole 825 of the first tool 800 and through it into the threaded through-hole 180 of the first base segment 105.

[0288] This will result in a single “rigid” body consisting of the first tool 800, the second tool 900, the locking screw 300 and the first base segment 105.

[0289] This “rigid” body can then be inserted as a whole into the second base segment 105, and the locking screw 300 is then screwed further into the end of said second base segment 105.

[0290] This procedure can then be repeated for further base segments 105 or for the tip segment 1 10, resulting in the assembly illustrated in figures 24 to 26.

[0291] Once the base segments 105 and the tip segment 1 10, if any, have been assembled, the resulting assembly may be screwed into a hole cut in a bone, in this case in the jawbone, so as to act as a surrogate for the roots of a tooth.

[0292] The screwing may be carried out by means of a commercial tool (a kind of torque spanner) that is coupled to the handle 810 of the first tool 800 and allows a known and accurate torque to be applied.

[0293] In the post-operative phase, it is possible to temporarily close the conical cavity 135 of the first base body 105 to prevent any kind of infiltration into the implant as a result of the temporary closure of the gingiva.

[0294] This can be achieved with a cap 950, an example of which is illustrated in figures 27-30. This cap 950 may comprise a head 955, configured for example as a disc having a longitudinal axis Q and two mutually opposed axial ends along said longitudinal axis Q, of which a first axial end 960 and a second axial end 965.

[0295] The cap 950 may further comprise a conical shank 970, which protrudes from the second axial end 965 of the head 955 and is tapered in order to narrow away from it.

[0296] This conical shank 970 can end, for example, with a flat bottom surface 975 orthogonal to the longitudinal axis Q.

[0297] Specifically, the conical shank 970 may have a conjugated or complementary shape to the conical cavity 135 of each base segment 105.

[0298] A conjugated or complementary shape always means that at least one strip of the conical shank 970, preferably the entire conical shank 970, has the same shape and dimensions, in negative, as a corresponding strip of the conical cavity 135, preferably the entire conical cavity 135.

[0299] Thus, for example, the generatrices of the side surface of the conical shank 970 may be inclined with respect to the longitudinal axis Q by the same angle (e.g. less than or equal to 5 sexagesimal degrees) as the generatrices of the side surface of the conical cavity 135.

[0300] The cross-sectional area of the conical shank 970, at the second axial end 965 of the head 955, may have the same diameter as the cross-sectional area of the conical cavity 135, at the first axial end 125 of the body 120.

[0301] Preferably, the height of the conical shank 970, i.e. the axial distance between the second axial end 965 of the head 955 and the bottom surface 975, is, however, less than the depth of the conical cavity 135, i.e. the axial distance between the first axial end 125 of the body 120 and the bottom surface 140, i.e. less than half of this depth.

[0302] The cap 950 can further comprise a cylindrical stem 980, which protrudes from the bottom surface 975 of the conical shank 970 and has a smaller diameter than the latter.

[0303] The free axial end of this cylindrical stem 980 has a threaded shank 985 which may be screwed into the threaded hole 175 of the base segment 105, so as to tighten the head 955 of the cap 950 against the first axial end 125 of the base segment 105 (see figures 31 and 32).

[0304] In order not to interfere with the head 310 of the locking screw 300, at the threaded shank 985, the cap 950 may include a coaxial cylindrical cavity 990 having a diameter not less than that of the head 310 and suitable to accommodate it.

[0305] At the second axial end 965 of the head 955, the cap 950 may comprise an annular channel 995, which is arranged coaxially and surrounds the base of the conical shank 970, i.e., it surrounds the cross-section of the conical shank 970 located at the second end 965 of the head 955.

[0306] The annular channel 995 may have a conjugated or complementary shape to the annular prominence 185 of the first base segment 105.

[0307] Again, a conjugated or complementary shape means that at least one strip of the annular channel 995, preferably the entire annular channel 995, has the same shape and dimensions, in negative, as a corresponding strip of the annular prominence 185, preferably the inner annular prominence 185.

[0308] At the first axial end 960 of the head 955, the cap 950 has a pyramidal shaped central seat 996, for example with a hexagonal base, which is suitable for making a prismatic coupling with a tool for screwing and unscrewing the cap 950, for example with the second tool 900 described above.

[0309] Then, after removal of the cap 950, if any, the dental implant 100 can be completed with the attachment segment 1 15 that carries the actual denture.

[0310] Specifically (see figs. 13 and 14), the coupling segment 1 15 can be assembled to the first base segment 105 by simply inserting the conical shank 265 of the coupling segment 1 15 axially into the conical cavity 135 of the first base segment 105, taking care that the prismatic prominence 275 protruding from the conical shank 265 is inserted in turn into the prismatic cavity 145 at the bottom of the conical cavity 135.

[0311] Also in this case, the conical coupling made between the conical shank 265 and the conical cavity 135 ensures centring between the base segment 105 and the attachment segment 1 15, which are therefore perfectly coaxial.

[0312] Furthermore, if the generatrices of the side surfaces of the conical shank 265 and the conical cavity 135 are inclined at an angle equal to or less than 5 sexagesimal degrees to the common longitudinal axis, it is advantageously possible to realise the Morse taper coupling that opposes reciprocal axial rotation and slippage.

[0313] At the same time, the coupling between the prismatic prominence 275 and the prismatic seat 145 achieves a prismatic coupling that makes the attachment segment 1 15 rotation- ally integral to the base segment 105.

[0314] In this case, however, it is not always necessary for the attachment segment 1 15 to assume a predetermined angular position with respect to the base segment 105, so (as mentioned above) it is not necessary for the prismatic prominence 275 to have a conjugated or complementary shape to that of the prismatic seat 145, as long as their coupling creates a prismatic connection between the attachment segment 115 and the base segment.

[0315] Although the axial constraint between coupling segment 1 15 and the base segment 105 can already be at least partially ensured by the Morse taper coupling, greater security of mutual constraint can be achieved with a locking element 400.

[0316] As illustrated in figure 14, this locking element 400 may comprise a cylindrical stem 405, which is suitable to fit, preferably to size, into the through-hole 290 of the attachment segment 1 15.

[0317] One axial end of this cylindrical stem 405 has an enlarged head 410 having a larger diameter than the through-hole 290 and suitable to be housed in the lowering 281 of the attachment segment 115.

[0318] The opposite axial end of the locking element 400, on the other hand, has a threaded shank 415 suitable to be screwed into the threaded hole 175 of the base segment 105, so as to clamp the attachment segment 1 15 between the base segment 105 and the enlarged head 410.

[0319] In order not to interfere with the head 310 of the locking screw 300, at the threaded shank 415, the locking element 400 may include a coaxial cylindrical cavity 420 having a diameter not less than that of the head 310 and suitable to accommodate it.

[0320] In order to allow the screwing and unscrewing of the locking element 400, the latter may comprise, in the centre of the enlarged head 410, a pyramidal shaped central seat 425, for example with a hexagonal base, similar to that made in the cap 950, which is suitable to create a prismatic coupling with a manoeuvring tool, for example with the second tool 900 described above.

[0321] After the assembly of the attachment segment 1 15, with the corresponding denture, dental implant 100 can be considered complete.

[0322] In certain circumstances, for example but not exclusively due to oral pathologies such as peri-implantitis, it may nevertheless be necessary to remove and possibly replace one of the base segments 105, typically the one proximal to the attachment segment 1 15, and replace it with a new one (the same or different from the previous one), without however removing the entire dental implant 100 from the patient's bone.

[0323] To perform this operation, it is first necessary to remove the attachment segment 115.

[0324] This can be done by simply unscrewing the locking element 400 and then axially separating the attachment segment 1 15 from the base segment 105 below, possibly using a tool that screws into the threaded portion 291 .

[0325] Then it is possible to unscrew the locking screw 300 that holds the base segment 105 and the tip segment 110 together.

[0326] In this regard, it should be emphasised that the function of the locking screw 300 is simply to achieve an axial constraint, while the rotational constraint, which serves to ensure the solidarity of the base 105 and tip 1 10 segments during screwing into the bone, is achieved by means of the prismatic couplings between the prismatic prominences 165 and the prismatic seats 145 and 225.

[0327] Consequently, the locking screw 300 does not need to be tightened with a particularly high torque.

[0328] This fact translates into an advantage during disassembly, since, in order to unscrew the locking screw 300, it will be sufficient to exert a relatively low torque, thus avoiding the risk of driving the base 105 and tip 1 10 segments into rotation, which could otherwise jeopardise the anchorage of the entire dental implant 100.

[0329] The locking screw 300 may be unscrewed and removed with the help of the second tool 900.

[0330] In any case, once the locking screw 300 has been unscrewed, the first base segment 105 can be extracted axially, preferably with the aid of a simple disassembly kit. As illustrated in figures 33 and 34, this disassembly kit can comprise a first tool 500 with a stem 505 that may be derived from a handle 510, shaped for example like a kind of plate.

[0331] The stem 505, which may be tapered in shape with a circular cross-section, has diameters such that it can freely slide into the conical cavity 135 and the prismatic seat 145 of the base segment 105, resting its free axial end in contact with the bottom surface 150 (see in particular figure 38).

[0332] For example, at least at said free axial end, the diameter of the stem 505 may be substantially the same as the diameter of the stem 405 of the locking element 400.

[0333] The first tool therefore comprises a threaded shank 515 which protrudes from the free axial end of the stem 505 and is suitable to be screwed into the threaded hole 175 of the base segment 105, as well as a central through-hole 520 which passes through the stem 505, the threaded shank 515 and the handle 510 and which, when the threaded shank 515 is screwed into the threaded hole 175, is coaxial to the through-hole 180 of the base segment 105.

[0334] The diameter of the central through-hole 520 is preferably larger than the diameter of the through-hole 180.

[0335] The disassembly kit can also include a rod 525, which, as shown in figure 35, may be equipped with a smooth portion 530 and a threaded portion 535.

[0336] The diameter of this rod 525 is smaller than the diameter of the central through-hole 520 of the first tool 500, so that it can be freely inserted and slide into it.

[0337] However, the threaded portion 535 is large enough to be engaged (e.g. screwed) into the through-hole 180 of the base segment 105 and the threaded hole of the tip segment 1 10. Lastly, the disassembly kit may include the second tool 900, which, as described above and illustrated in figures 21 , 22 and 23, may have a stem 905 and possibly a handle 910, from which said stem 905 is derived.

[0338] The diameter of the stem 905 may be substantially the same, or at least not larger, than the diameter of the central through-hole 520 of the first tool 500, so that it may be slidably and rotatably inserted into it.

[0339] The free end of this stem 905 carries a manoeuvring key, e.g., the prominence 915, which is suitable to be engaged with a corresponding pyramidal cavity 540, e.g., of hexagonal cross-section, made at the free axial end of the smooth portion 530 of the rod 525, so as to achieve a prismatic coupling with said cavity 540.

[0340] Thus, after screwing the first tool 500 into the threaded hole 175 of the first base segment 105, it is possible to insert the rod 525 into the central through-hole 520 and, using the second tool 905, screw its threaded portion 535 partly into the threaded hole 235 of the tip segment 1 10 and partly into the through-hole 180 of the second base segment 105. Alternatively, the rod 525 could be screwed into the tip segment 110 and the second base segment 105, before inserting and screwing the first tool 500 into the first base segment 105.

[0341] The important thing is that, at the end of the screwing, the through-hole 180 of the first base segment 105 (the one to be removed) is only affected / crossed by the smooth portion 530 of the rod 525, and that the threaded portion 535 is screwed to all the other segments of the dental implant 100, so as to ensure that they remain stationary and clamped together.

[0342] After screwing the rod 525 in this manner, it is in fact sufficient to pull the first tool 500 screwed into the threaded hole 175 to axially extract the base segment 105 separating it from the others.

[0343] In conclusion, we would like to emphasise that, although only two possible models of base segments 105 (the wider and shorter one proximal to the attachment segment 1 15 and the narrower and longer one proximal to the tip segment) emerged in the previous discussion, the system provides for the possibility of making available a wide range of base segments 105 that may be chosen and assembled together at the dentist's discretion, in order to create the denture 100 that best suits his or her needs.

[0344] All of these base segments 105 will share the same general geometry and, in particular, may be identical with regard to the shape and dimensions of the conical cavity 135, the prismatic seat 145, the conical shank 155, the prismatic prominence 165, the threaded hole 175, the through-hole 180, the annular prominence 185 and the annular channel 190, while they may differ with regard to the axial extension (height), the shape (e.g., conical or cylindrical) and the external diameter of the body 120 and with regard to the characteristics of the helical thread 195, which may, for example, have a different number of principles and / or a different shape.

[0345] The same naturally applies to the tip segment 1 10 and the attachment segment 1 15.

[0346] It is also pointed out that, although an example has been illustrated in which the dental implant 100 comprises two base segments 105 comprised between a tip segment 1 10 and an attachment segment 1 15, it is not excluded that, in other embodiments, the dental implant 100 may comprise a different number and type of segments.

[0347] For example, other dental implants 100 might comprise a single base segment 105 comprised between a tip segment 110 and an attachment segment 115, or any number of base segments 105 greater than the two illustrated in the drawings.

[0348] Still other embodiments might lack the attachment segment 1 15, at least the one illustrated in the figures, which could be replaced by any other abutment suitable for anchoring to a base segment 105 of the system.

[0349] Figures 43 and 44 illustrate a variant of the modular dental implant 100 described in the previous pages.

[0350] Since all the features described in the previous pages can also be found in this variant, in the following we will omit repeating the description of these features, which are however intended to be included also in this variant, limiting ourselves to pointing out the aspects of diversity, which in turn can also be applied to the embodiments described above.

[0351] Specifically, the variant illustrated in figures 43 and 44 provides that the through-hole 180 of each base segment 105 is not completely threaded, but has a threaded portion 180A and a smooth portion 180B (see also figure 42).

[0352] The smooth portion 180B is axially interposed between the threaded portion 180A and the threaded hole 175 and has a diameter between the diameter of the threaded portion 180A and the diameter of the threaded hole 175.

[0353] In other words, the diameter of the smooth portion 180B is greater than the diameter (e.g. pitch diameter) of the threaded portion 180A and is smaller than the diameter (e.g. pitch diameter) of the threaded hole 175.

[0354] Corresponding chamfers 181 , made, for example, by mechanical machining with swarf removal, can also be provided between the prismatic seat 145 and the threaded hole 175, between the latter and the smooth portion 180B and between the latter and the threaded portion 180A,.

[0355] While the threaded portion 180A is suitable for receiving in screwing the threaded stem 305 of the locking screw 300, according to the same methods described previously (see fig.44), the smooth portion 180B (of the first base segment 105) is suitable to accommodate, for example substantially to measure, the head 310, so that the latter can be completely inserted into the through hole 180 and does not remain located inside the threaded hole 175.

[0356] In this way, the locking element 400 of the attachment segment 115 can be devoid of the coaxial cylindrical cavity 420 described previously, and the threaded shank 415 can pos- sibly abut directly against the head 310 of the locking screw 300.

[0357] According to another aspect of the variant described in figure 43, the external thread 195 of at least one of the base segments 105 and / or the external thread 245 of the tip segment 110, can be provided with recesses 182 for chip evacuation bone during tightening.

[0358] Obviously, a person skilled in the art may make several technical-applicative modifica- tions to all that above, without departing from the scope of the invention as hereinbelow claimed.

Claims

CLAIMS1. A modular dental implant (100) comprising a plurality of segments suitable to be axially joined together, of which at least one base segment (105) comprising:- a body (120) having a longitudinal axis (A) and two mutually opposed axial ends along said longitudinal axis (A), of which a first axial end (125) and a second axial end (130),- a conical cavity (135) having an axis coincident with the longitudinal axis (A), which is formed at the first axial end (125) of the body (120) and tapered towards the second end (130),- a prismatic seat (145) formed on a bottom surface (140) of said conical cavity (135),- a conical shank (155) coaxial to and having a conjugated shape to the conical cavity (135), which protrudes from the second axial end (130) of the body (120) and is tapered away from it, and- a prismatic prominence (165) having a conjugated shape to the prismatic seat (145) and protruding from a bottom surface (160) of the conical shank (155).

2. A modular dental implant (100) according to claim 1 , wherein the side surfaces of the conical cavity (135) and the conical shank (155) of the base segment (105) have generatrices inclined with respect to the longitudinal axis (A) by an angle less than or equal to 5 sexagesimal degrees.

3. A modular dental implant (100) according to claim 1 or 2, wherein the prismatic seat (145) of the base segment (105) has a cross-section in the shape of an irregular polygon.

4. A modular dental implant (100) according to any one of the preceding claims, wherein the base segment (105) comprises a through-hole (180) coaxial with the conical cavity (135).

5. A modular dental implant (100) according to claim 4, comprising a locking screw (300) having a threaded stem (305) suitable to be engaged in said through-hole (180) and a head (310) positioned at one end of said threaded stem (305) and having a diameter greater than the diameter of the through-hole (180).

6. A modular dental implant (100) according to any one of the preceding claims, wherein the base segment (105) comprises a threaded hole (175) coaxial with the conical cavity (135), which is formed on a bottom surface (150) of the prismatic seat (145).

7. A modular dental implant (100) according to any one of the preceding claims, wherein said base segment (105) further comprises:- an annular prominence (185), coaxial with the conical cavity (135) and protruding from the first end (125) of the body (120), and- an annular channel (190), having a conjugated shape to the annular prominence (185), which is coaxial with the conical shank (155) and is formed at the second end (130) of the body (120).

8. A modular dental implant (100) according to any one of the preceding claims, wherein the base segment (105) comprises a helical thread (195), which is made on an outer side surface of the body (120).

9. A modular dental implant (100) according to any one of the preceding claims, wherein the segments comprise a tip segment (1 10) comprising:- a body (200) having a longitudinal axis (B) and two mutually opposed axial ends along said longitudinal axis, of which a first axial end (205) and a second axial end (210),- a conical cavity (215) having an axis coincident with the longitudinal axis (B) and a conjugated shape with the conical shank (155) of the base segment (105), which is formed at the first axial end (205) of the body (200) and tapered towards the second end (210), and- a prismatic seat (225) formed on a bottom surface (220) of said conical cavity (215) and having a conjugated shape to the prismatic prominence (165) of the base segment (105).

10. A modular dental implant (100) according to claim 9, wherein the tip segment (1 10) comprises a threaded hole (235) coaxial with the conical cavity (215) and formed on a bottom surface (230) of the prismatic seat (225).

11. A modular dental implant (100) according to any one of claims 9 to 10, wherein said tip segment (110) further comprises:- an annular prominence (240), having a conjugated shape to the annular channel (190) of the base segment (105), which is coaxial with the conical cavity (215) and protrudes from the first axial end (205) of the body (200).

12. A modular dental implant (100) according to any one of claims 9 to 1 1 , wherein the tip segment (1 10) comprises a helical thread (245), which is made on an outer sidesurface of the body (200).

13. A modular dental implant (100) according to any one of the preceding claims, comprising a protective cap (950) comprising:- a conical shank (970) having a longitudinal axis (Q) and conjugated shape to the conical cavity (135) of the base segment (105),- a head (955) placed at an axial end of the conical shank (970) and having a radial extension greater than it,- and a stem (980) placed at the opposite axial end of the conical shank (970) and having at least one threaded portion (985) suitable for screwing into the threaded hole (175) in the bottom surface (150) of the prismatic seat (145) of the base segment (105).

14. A modular dental implant (100) according to claim 13, wherein the conical shank (970) of the protective cap (950) has an axial extension less than the axial extension of the conical cavity (135) of the base segment (105).

15. A modular dental implant (100) according to claim 13 or 14, wherein the protective cap (950) comprises an annular channel (995), having a conjugated shape to the annular prominence (185) of the base segment (105), which is coaxial to the conical shank (970) and is formed on a surface (965) of the head (955) from which the conical shank (970) itself protrudes.

16. A modular dental implant (100) according to any one of the preceding claims, wherein the segments comprise an attachment segment (1 15) for dentures comprising:- a body (250) having a longitudinal axis (C) and two mutually opposed axial ends along said longitudinal axis, of which a first axial end (255) and a second axial end (260),- a conical shank (265) having an axis coincident with the longitudinal axis (C) and a conjugated shape to the conical cavity (135) of the base segment (105), which protrudes from the second axial end (260) of the body (250) and is tapered away from it, and- a prismatic prominence (275) protruding from a bottom surface (270) of the conical shank (135) and suitable to fit into the prismatic seat (145) of the base segment (105).

17. A modular dental implant (100) according to claim 16, wherein said attachmentsegment (1 15) further comprises:- an annular channel (285), having a conjugated shape to the annular prominence (185) of the base segment (105), which is formed at the second end (260) of the body (250) and is coaxial with the conical shank (265).

18. A modular dental implant (100) according to claim 16 or 17, wherein the attachment segment (1 15) comprises a through-hole (290) having an axis coincident with the longitudinal axis (C).

19. A modular dental implant (100) according to claim 18, comprising a locking element (400) having a cylindrical stem (405) suitable to be inserted into the through-hole (290) of the attachment segment (1 15), a head (410) having a larger diameter than the through- hole (290) and located at an axial end of the cylindrical stem (405), and a threaded shank (415) located at the opposite axial end of the cylindrical stem (405) and suitable to be screwed into the threaded hole (175) formed on the bottom surface (150) of the prismatic seat (145) of the base segment (105).

20. A modular dental implant (100) according to claim 19, wherein the attachment segment (1 15) comprises a lowering (281 ) suitable to accommodate the head (410) of the locking element (400).

21. A modular dental implant (100) according to any one of claims 18 to 20, wherein said through-hole (290) of the attachment segment (1 15) comprises at least one threaded portion (291 ).

22. A modular dental implant (100) according to claim 4, wherein said through hole (180) includes at least one threaded portion (180A) and at least one smooth portion (180B) having a larger diameter than the threaded portion (180A), and wherein the implant (100) further comprises a locking screw (300) having a threaded stem (305) adapted to engage in said threaded portion (180A) of the through hole (180) and a head (310) positioned at an end of said threaded stem (305), having a diameter greater than the diameter of the threaded portion (180A) of the through hole (180) and capable of being accommodated in the smooth portion (180B).

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