Improved Threaded Dental Implant - Patent application

Abstract

The dental implant (1) comprises an implant body (2) extending along a longitudinal axis (II) between a coronal end (2a) and an apical end (2b), the implant body (2) comprising a core (3) along which extends a helical thread (4) having at least one thread (F1, F2), the dental implant (1) comprising at least one section (T2, T3), in which the thread (4) gradually extends in the direction of the coronal end (2a). and the core (3) is tapered in the direction of the apical end (2b), and at least one thread (F1, F2) comprises an apical surface (SA1, SA2) facing the apical end (2b) of the dental implant, a coronal end surface (SC1, SC2) facing the coronal end (2a) of the dental implant (1), and peripheral outer surfaces (SLP1, SLP2) connecting the apical surface (SA1, SA2) and the coronal end surface (SC1, SC2) of at least one thread (F1, F2), - the apical surface (SA1, SA2) of at least one thread (F1, F2) has, in a cross section along the longitudinal axis (II), a first profile which is repeated according to an apical pitch, and - the coronal end surface (SC1, SC2) of at least one thread (F1, F2) has, in a cross section along the longitudinal axis (II), a second profile which is repeated according to the coronal pitch. According to the invention, in at least one section (T2, T3) the apical pitch is greater than the coronal pitch.

Description

[Technical field]

[0001] The present invention relates to the field of dental implants, in particular to dental implants intended to be inserted into the maxilla or mandible of a patient to receive and hold a dental prosthesis. [Background technology]

[0002] When inserting an implant into a patient's maxilla or mandible, it is important to obtain the best possible post-implant stability (also known as primary stability) so that said implant can be inserted as quickly or immediately as possible, i.e. before the bone has colonized the sides of the implant.

[0003] The primary stability of an implant depends, inter alia, on the density of the bone in which the implant is placed.

[0004] In the case of low bone density (conventionally a density of D3 or D4 according to the Misch classification), a cylindrical hole is drilled in the maxilla or mandible, into which an endo-bone part of a dental implant is then inserted, the volume of which is greater than the volume of the hole drilled in the bone. For example, it is possible to use a known dental implant comprising an implant body extending along a longitudinal axis between a coronal end and an apical end, said implant body having a core along which a helical thread with at least one thread extends, said dental implant having at least one segment, in which at least one segment the thread has a height which gradually decreases in the direction of the coronal end, and the core is tapered in the direction of the apical end, said at least one thread having an apical surface directed towards the apical end of the dental implant, a coronal surface directed towards the coronal end of the dental implant, and a peripheral outer surface connecting the apical surface and the coronal surface of said at least one thread. A dental implant of this kind is described, for example, in US Pat. No. 5,399,313. The dental implant generally has an apical end whose cross section is substantially equal to the cross section of the cylindrical hole, during its insertion it gradually compresses the bone around the drilled hole in the bone so as to improve the primary stability.

[0005] However, if this type of dental implant is inserted into bone of higher density (traditionally D1 or D2 density according to the Misch classification), the bone density makes the bone less compressible and, as a result, the penetration of the dental implant requires a much higher screw torque, which may even be too high for the dental implant to withstand without being damaged (especially at the level of its connector arrangement that allows screwing by rotational drive).

[0006] US 6,399,436 describes a dental implant conforming to the preamble of claim 1. Thus, at least one thread of said dental implant comprises an apical surface directed towards the apical end of the dental implant, a coronal surface directed towards the coronal end of the dental implant and a peripheral outer surface connecting the apical and coronal surfaces of said at least one thread. The apical surface of said at least one thread implicitly has a first profile which is repeated according to an apical pitch in a cross section along the longitudinal axis of the dental implant, and the coronal surface of said at least one thread implicitly has a second profile which is repeated according to a coronal pitch in a cross section along the longitudinal axis of the dental implant. However, in said document there is no explicit mention of the apical and coronal pitches of threads in the sense of the present invention. Also, there is no mention of any difference that may exist between the apical and coronal pitches or of any features which may have the consequence of inducing a difference between the apical and coronal pitches. On the contrary, the apical and coronal pitches of the threads of the implant appear to be equal. Also, there is no explanation as to how the dental implant is manufactured. The same is true for US Pat. Nos. 5,993, 6,133, 6,141, 6,223, 6,367, 6,471, 6,514, 6,671, 6,771, 6,821, 6,971 [Prior art documents] [Patent documents]

[0007] [Patent Document 1] EP1624826 [Patent Document 2] US2008 / 261175 [Patent Document 3] WO2017 / 129826 [Patent Document 4] EP2570096 Summary of the Invention [Problem to be solved by the invention]

[0008] One problem addressed by the present invention is to provide a dental implant that can be inserted into low density bone and compress the bone for good primary stability, but also be inserted into denser bone without the screw insertion torque being too high for this. [Means for solving the problem]

[0009] In order to achieve the above and other objects, the invention proposes an implant body extending along a longitudinal axis between a coronal end and an apical end, said implant body having a core along which extends a helical thread having at least one thread, said dental implant having at least one segment, in which the thread has a height which gradually decreases in the direction of the coronal end and the core is tapered in the direction of the apical end, said at least one thread having an apical surface oriented towards the apical end of the dental implant, a coronal surface oriented towards the coronal end of the dental implant and a peripheral outer surface connecting the apical surface and the coronal surface of said at least one thread: - the apical surface of the at least one thread has, in a cross section along the longitudinal axis (II), a first profile which repeats according to an apical pitch, - the coronal end face of the at least one thread has, in a cross section along the longitudinal axis, a second profile which repeats according to a coronal pitch; In said at least one segment, the apical pitch is greater than the coronal pitch.

[0010] In the prior art implants described in the patents 6, 10, 11, 12, 13, 14, the coronal pitch and the apical pitch are equal. In the segment where the thread has a gradually decreasing height in the coronal direction and the core is tapered in the apical direction, the width of the peripheral outer surface (along the longitudinal axis) of the thread increases in the coronal direction. As a result, in this segment, the thread radially presses against the bone more near the coronal end than near the apical end, which significantly increases the screw torque as and when the dental implant segment is inserted into the bone.

[0011] In the dental implant according to the invention, by providing the thread with an apical pitch that is greater than the coronal pitch in the segments where the thread has a gradually decreasing height in the coronal direction and the core is tapered in the apical direction, the increase in width of the peripheral outer surface (along the longitudinal axis) in the coronal direction is less, which therefore reduces the screw insertion torque.

[0012] To facilitate the manufacture of the implant, in the first embodiment the coronal pitch and the apical pitch may advantageously be constant.

[0013] The apical and coronal pitches may preferably be selected such that the ratio of the larger and smaller apical and coronal pitches belongs to the interval [1;1.1]. In this way, good results are obtained in terms of reducing the screw insertion torque.

[0014] In a second embodiment, one of the coronal and apical pitches is constant and the other of the coronal and apical pitches gradually increases, so that the coronal or apical pitch can be varied to obtain a peripheral outer surface of substantially constant width (along the longitudinal axis) in a segment in which the thread has a gradually decreasing height in the coronal direction and the core tapers in the apical direction.

[0015] In order to gradually compress the bone, the core may advantageously be conically tapered in the direction of the apical end over at least one segment of the length of said implant.

[0016] In at least one segment of the length of said implants in which the core is tapered in the apical direction, the thread may advantageously be tapered in the apical direction, preferably conical.

[0017] In at least one segment of the implant length as described above: the core and the screw are preferably conical; The core advantageously has a taper that is greater than the taper of the screw.

[0018] According to another aspect, the invention proposes a method for manufacturing a dental implant comprising an implant body extending along a longitudinal axis between a coronal end and an apical end, said implant body having a core along which extends a helical thread having at least one thread, said implant body comprising: a) During the first thread cutting cycle: - in at least one segment of the dental implant, said at least one thread has a gradually decreasing height in the direction of the coronal end and the core is tapered in the direction of the apical end, - said at least one thread has a coronal end surface oriented substantially in a coronal direction; - the at least one thread has an apical surface oriented substantially in an apical direction; said at least one thread having a peripheral outer surface connecting an apical surface and a coronal surface; At least one thread is formed by the thread cutting tool in a longitudinal relative movement according to a first pitch, b) during a second thread cutting cycle, in at least one length segment of said dental implant, a thread cutting tool in a longitudinal relative movement according to a second pitch: - an apex surface, wherein the second pitch is greater than the first pitch; and / or a coronal end surface, the second pitch being smaller than the first pitch; It is characterized in that it is used to re-cut.

[0019] This type of method makes it possible to obtain a dental implant with a reduced screw insertion torque compared to a dental implant in which the first pitch and the second pitch are equal in the above-mentioned segments, in which the thread has a gradually decreasing height in the direction of the coronal end and the core tapers in the direction of the apical end.

[0020] For ease of manufacturing, the first pitch and the second pitch may advantageously be constant.

[0021] The ratio of the larger to the smaller pitch of the first and second pitches preferably lies in the interval [1;1.1].

[0022] The first pitch and the second pitch may advantageously be between 0.6 mm and 3 mm. [Brief description of the drawings]

[0023] Other objects, features and advantages of the present invention will become apparent from the following description of specific embodiments thereof, which is given with reference to the accompanying drawings. [Figure 1] FIG. 2 is a side view of one particular embodiment of a dental implant according to the invention after a first manufacturing step. [Diagram 2] FIG. 2 is a side view of one particular embodiment of a dental implant according to the present invention after a second manufacturing step. [Diagram 3] 1 is a side view of a particular embodiment of a dental implant according to the present invention upon completion of manufacture. [Figure 4] FIG. 4 is a partial view in longitudinal section of the dental implant of FIG. 3. [Diagram 5]4 is a graph showing the insertion torque of the dental implant of FIG. 3 and a dental implant not according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In figures 3 and 4 one particular embodiment of a dental implant 1 according to the invention is shown.

[0025] The dental implant 1 comprises an implant body 2 extending along a longitudinal axis II between a coronal end 2a and an apical end 2b, said implant body 2 having a core 3 along which extends a helical thread 4 having at least one thread, where the thread 4 comprises two threads F1 and F2.

[0026] The threads F1 and F2 respectively comprise apical faces SA1 and SA2 directed towards the apical end 2b of the dental implant 1 and coronal faces SC1 and SC2 directed towards the coronal end 2a of the dental implant 1. A peripheral outer surface SLP1 connects the apical face SA1 and the coronal face SC1. A peripheral outer surface SLP2 connects the apical face SA2 and the coronal face SC2.

[0027] The external shape of the implant body 2 and that of its core 3 are highlighted in more detail in Figures 1 to 4 by the outer covering 5 and the dashed lines of the implant body 2. It can thus be seen that the implant body 2 comprises five successive segments T1 to T5 from its coronal end 2a to its apical end 2b.

[0028] In segment T1, the core 3 is substantially cylindrical and the thread 4 is conical tapering towards the coronal end 2a. The height H (in a plane substantially perpendicular to the longitudinal axis II) of the threads F1 and F2 thus decreases in the direction of the coronal end 2a. This gradual decrease in the cross section of the dental implant 1 in the direction of its coronal end 2a makes it possible to take into account the bone volume that is thinned near the bony crest of the maxilla or mandible in the vestibular-palatal direction. This allows an aesthetic integration of the dental implant 1.

[0029] In segment T2, the core 3 tapers in the direction of the apical end 2b, tapering at a taper angle A3 towards the apical end 2b, and the thread 4 is substantially cylindrical with a constant radius R. Thus, the height H (in a plane substantially perpendicular to the longitudinal axis II) of the threads F1 and F2 gradually increases in the direction of the apical end 2b, and the width L (along the longitudinal axis) of the peripheral outer surfaces SLP1 and SLP2 of the threads F1 and F2 gradually increases in the direction of the coronal end 2a.

[0030] In segment T3, the core 3 is also conical. Its taper is the same as in segment T2. The thread 4 is also conical, tapering in the direction of the apex 2b and tapering towards the apex 2b. The change in height H of the thread 4 depends on the relationship between the cone angles A3 and A4 of the core 3 and the thread 4, respectively: - if the cone angle A3 of the core 3 is greater than the cone angle A4 of the thread 4, the height H of the thread 4 increases in the direction of the apex 2b, - if the cone angle A3 of the core 3 is equal to the cone angle A4 of the thread 4, then the height H of the thread 4 is substantially constant in the direction of the apical end 2b, If the cone angle A3 of the core 3 is smaller than the cone angle A4 of the thread 4, the height H of the thread 4 decreases in the direction of the apex 2b.

[0031] In the particular embodiment shown in the figure, the cone angle A3 is greater than the cone angle A4, so that the height H of the thread 4 increases in the direction of the apex end 2b.

[0032] In segment T4, the core 3 is also conical. Its taper is the same as in segments T2 and T3. The thread 4 is partially rounded.

[0033] Segment T5 is convex in the form of a semi-lens and is completely arbitrary.

[0034] The core 3 therefore tapers in the direction of the apical end 2b over at least one segment of the length of the dental implant 1, here over segments T2 to T4.

[0035] In segment T2, the thread 4 has a height H (along a radial axis perpendicular to the longitudinal axis II) that gradually decreases in the direction of the coronal end 2a. The core then tapers in the direction of the apical end 2b and is more specifically conical with a cone angle A3. All this can be seen more specifically in Figure 4, which is a detailed view in longitudinal section of segment T2 of the dental implant 1 of Figure 3.

[0036] In this Figure 4: - the apex faces SA1 and SA2 of the threads F1 and F2 have, in a cross section along the longitudinal axis II, first contours PP1 and PP2 which are repeated according to an apex pitch PA, - the coronal end faces SC1 and SC2 of the threads F1 and F2 have, in a cross section along the longitudinal axis II, second contours DP1 and DP2 which are repeated according to a coronal end pitch PC, - The apical pitch PA is greater than the coronal pitch PC We can see that...

[0037] Here, the coronal pitch PC and the apical pitch PA are constant. The ratio of the apical pitch PA to the coronal pitch PC belongs to the interval [1;1.1]. In the example shown in FIG. 4, the apical pitch is 2.03 mm and the coronal pitch is 2 mm. The ratio of the apical pitch PA to the coronal pitch PC is therefore more specifically 1.015.

[0038] Alternatively, one of the coronal pitch PC or the apical pitch PA may be constant, and the other of the coronal pitch PC or the apical pitch PA gradually increases.

[0039] In segment T3, it can be seen in FIG. 3 that the core 3 tapers in the direction of the apical end 2b (more precisely, conical with an angle A3) and that the thread 4 is also tapered in the direction of the apical end 2b and conical with an angle A4. In segment T3, due to having a height H of the thread 4 (along a radial axis perpendicular to the longitudinal axis II) that gradually decreases in the direction of the coronal end 2a, the core 3 has a greater taper than that of the thread 4, i.e., in fact, the angle A3 is greater than the angle A4. In segment T3, the threads F1 and F2 have the same coronal pitch PC and apical pitch PA characteristics, i.e. the apical pitch is greater than the coronal pitch PC.

[0040] The manufacture of a dental implant is explained in more detail with the aid of FIGS.

[0041] In FIG. 1, an implant body 2 is seen which has been machined according to a first thread-cutting cycle. During this first thread-cutting cycle: - in segments T2 and T3 of the length of the dental implant 1, the threads F1 and F2 have a height H (along a radial axis perpendicular to the longitudinal axis II) which gradually decreases in the direction of the coronal end 2a and the core 3 tapers in the direction of the apical end 2b, - the threads F1 and F2 each comprise a coronal end face SC1 and SC2 oriented substantially towards the coronal end 2a, the threads F1 and F2 each comprise an apical face SA1 and SA2 oriented substantially towards the apical end 2b, - the threads F1 and F2 each include a peripheral outer surface SLP1 and SLP2, respectively, one connecting the apical surface SA1 with the coronal surface SC1 and the other connecting the apical surface SA2 with the coronal surface SC2; Thus, the threads F1 and F2 are formed by the thread cutting tool in a relative longitudinal movement at a first pitch P1.

[0042] 1, it can be seen that in segments T2 and T3, the width L (in a radial plane with longitudinal axis II) of the peripheral outer sides SLP1 and SLP2 increases relatively strongly in the direction of the coronal end 2a, which results in a significant increase in the screw insertion torque of the dental implant 1 as and when segments T2 and T3 are inserted into the bone.

[0043] To reach the dental implant 1 of FIG. 2, during a second thread cutting cycle, in segments T2 and T3 of the length of the dental implant 1, the apical faces SA1 and SA2 and / or the coronal faces SC1 and SC2 of the threads F1 and F2 are re-cut by the thread cutting tool in a longitudinal relative movement with a second pitch P2 different from the first pitch P1.

[0044] More precisely: - if the second pitch P2 is greater than the first pitch P1, the apical faces SA1 and SA2 are recut and therefore the second pitch P2 is equal to the apical pitch PA and is greater than the first pitch P1, which is the coronal pitch PC (defined by the non-recut coronal faces SC1 and SC2, as shown in FIG. 4); - if the second pitch P2 is smaller than the first pitch P1, the coronal end faces SC1 and SC2 are recut and therefore the second pitch P2 is equal to the coronal end pitch PC and smaller than the first pitch P1, which is the apical pitch PA (defined by the non-recut apical end faces SA1 and SA2).

[0045] The second thread cutting cycle results in a decrease in the width L (in a radial plane with the longitudinal axis II) of the peripheral outer sides SLP1 and SLP2, which decrease gradually increases in the direction of the coronal end 2a. It is thus possible to at least partially counteract the increase in the width L (in a radial plane with the longitudinal axis II) of the peripheral outer sides SLP1 and SLP2 in the direction of the coronal end 2a, including when the dental implant 1 is subjected to the first thread cutting cycle (FIG. 1).

[0046] In figure 2 it can be seen that in segments T2 and T3 the width L (along the longitudinal axis II) of the peripheral outer sides SLP1 and SLP2 does not increase as drastically in the direction of the coronal end 2a as in figure 1. This significantly reduces the increase in the insertion torque of segments T2 and T3 (and therefore of dental implant 1) as and when they penetrate the bone.

[0047] After the second thread cutting cycle, multiple tapping grooves such as grooves R1 and R2 (FIG. 3) may be formed in the thread 4 to make the dental implant 1 self-tapping.

[0048] The effect of the present invention in reducing screw insertion torque is shown in the graph of FIG. 5, which shows the insertion torque (N.cm) as a function of penetration (mm) by screwing two dental implants into a polyurethane biomechanical test block of density 40 PCF (pounds per cubic foot), which represents dense bone.

[0049] Curve C1 relates to a dental implant similar to that in Figure 1 (but additionally provided with three tapping grooves similar to the tapping grooves R1 and R2 in Figure 3) with a total length of 12 mm and a maximum outer diameter (in segment T2) of 4 mm. This dental implant was inserted by screwing into a hole with an inner diameter of 3.6 mm.

[0050] Curve C2 relates to a dental implant 1 according to the invention shown in Figure 3 (with three tapping grooves similar to the tapping grooves R1 and R2 in Figure 3), with a total length of 12 mm and a maximum outer diameter (in segment T2) of 4 mm. This dental implant was inserted by screwing into a hole with an inner diameter of 3.6 mm.

[0051] It can be seen that the insertion torque shown by curve C1 increases rapidly up to 80 N.cm for a penetration travel of just under 10 mm. Then, screwing was interrupted at 80 N.cm in order not to damage the connector arrangement inside the dental implant that allows it to be driven in rotation for screwing in. This means that, in practice, the insertion of the dental implant failed: it was not possible to do this in the block over its entire length of 12 mm.

[0052] It can be seen that the insertion torque of the dental implant 1 according to the invention, illustrated by curve C2, does not increase so rapidly. For a penetration of about 10 mm, the insertion torque is about 50 N.cm, which is much smaller than the 80 N.cm of the implant not according to the invention. This allows the dental implant 1 to be successfully inserted up to its entire length of 12 mm without exceeding an insertion torque of 70 N.cm, which is unlikely to damage the internal connector arrangement of the dental implant 1 that allows it to be driven in rotation for screwing.

[0053] Curve C2 has a smaller slope than curve C1: the increase in screw insertion torque is significantly attenuated as a result of the invention.

[0054] The invention is not limited to the embodiments expressly described, but includes various variants and generalizations thereof encompassed within the scope of the appended claims.

Claims

1. 1. A dental implant comprising an implant body extending along a longitudinal axis between a coronal end and an apical end, said implant body having a core along which a helical thread having at least one thread extends, said dental implant having at least one segment, in which the thread has a height that gradually decreases in the direction of said coronal end, and said core tapering in the direction of said apical end, said at least one thread having an apical end surface directed towards the apical end of said dental implant, a coronal end surface directed towards the coronal end of said dental implant, and a peripheral outer surface connecting said apical end surface and said coronal end surface of said at least one thread, the apex face of said at least one thread has, in a cross section along said longitudinal axis, a first profile which repeats according to an apex pitch; the coronal end face of said at least one thread has, in a cross section along said longitudinal axis, a second profile which repeats according to a coronal end pitch; 4. A dental implant comprising: a first end portion and a second end portion, the first end portion being apical and the second end portion being coronal.

2. The dental implant of claim 1 , wherein the coronal pitch and the apical pitch are constant.

3. 3. The dental implant of claim 2, wherein the ratio of the apical pitch to the coronal pitch is in the range of 1 to 1.1, excluding the value 1.

4. 2. The dental implant of claim 1, wherein the thread has a height that gradually decreases in the direction of the coronal end and the core has, in the segment tapering in the direction of the apical end, one of the coronal end pitch and the apical end pitch being constant and the other of the coronal end pitch and the apical end pitch gradually increasing so as to obtain a peripheral outer surface of substantially constant width along the longitudinal axis.

5. 5. Dental implant according to claim 1, characterized in that the core is conically tapered in the direction of the apical end on the at least one segment of the dental implant.

6. 6. Dental implant according to claim 5, characterized in that in at least one segment of the dental implant in which the core is tapered in the direction of the apical end, the thread is tapered in the direction of the apical end, preferably conical.

7. In at least one segment of the dental implant - said core and said screw are conical; A dental implant according to claim 6, characterized in that the core has a taper that is greater than the taper of the screw.

8. 1. A method of manufacturing a dental implant comprising an implant body extending along a longitudinal axis between a coronal end and an apical end, said implant body having a core with a helical thread having at least one thread extending along said core; a) during a first thread cutting cycle, - in at least one segment of the dental implant, said at least one thread has a gradually decreasing height in the direction of said coronal end and said core is tapered in the direction of said apical end, said at least one thread has a coronal end face oriented substantially towards said coronal end, - said at least one thread has an apical surface oriented substantially towards said apical end, - said at least one thread has a peripheral outer surface connecting said apical end surface and said coronal end surface; At least one thread is formed by the thread cutting tool in a longitudinal relative movement according to a first pitch, b) during a second thread cutting cycle, a thread cutting tool in a longitudinal relative movement according to a second pitch in at least one length segment of said dental implant; the apex face, wherein the second pitch is greater than the first pitch, or - said coronal end face, said second pitch being smaller than said first pitch; The manufacturing method is characterized in that it is used for recutting.

9. The method of claim 8 , wherein the first pitch and the second pitch are constant.

10. 10. The method of claim 9, wherein the ratio of the maximum pitch to the minimum pitch of the first pitch and the second pitch is in the range of 1 to 1.1, excluding the value of 1.

11. The method according to any one of claims 8 to 10, characterized in that the first pitch and the second pitch are between 0.6 mm and 3 mm.

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