Dental implant with improved thread
By designing the thread structure of dental implants, the thread gradually decreases in the coronal end direction and the core gradually becomes thinner in the apical direction, with the apical distance greater than the crown distance, the poor stability of dental implants in low-density bones is solved. and the problem of high torque in high-density bones achieve the effect of reducing the screw insertion torque in high-density bones.
Patent Information
- Application Number
- CN202080049441.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2019-07-08
- Filing Date
- 2020-07-04
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2040-07-04
AI Technical Summary
Existing dental implants are difficult to obtain good primary stability in low-density bones, and high twisting torque is required when inserted in high-density bones, which easily damages the connection device.
Design a dental implant whose threads gradually decrease in the direction of the coronal end and the core gradually tapers in the direction of the apical end. The top surface and the coronal surface of the spiral have different pitches, and the top distance is greater than the crown distance, so as to Reduce screw insertion torque.
Improve primary stability in low-density bones, while reducing screw insertion torque in high-density bones to avoid damage to the connection device.
Smart Images
Figure CN114072095B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of dental implants, and more particularly to a dental implant intended to be inserted into the maxillary or mandibular bone of a patient to receive and carry a dental prosthesis. Background Art
[0002] When inserting an implant into the maxillary or mandibular bone of a patient, it is important to achieve the best possible post-implantation stability (also called primary stability) in order to be able to load the implant as quickly or even immediately, ie before the bone colonizes the sides of the implant.
[0003] The primary stability of an implant depends inter alia on the density of the bone in which it is implanted.
[0004] When the bone is of low density (typically density D3 or D4 according to Misch classification), a cylindrical hole is produced in the maxillary or mandibular bone by means of a drill, and then the intraosseous part of the dental implant is inserted into the hole, the intraosseous part having a volume greater than the volume of the hole formed in the bone. For example, a known dental implant can be used, which comprises an implant body extending between a coronal end and an apex along a longitudinal axis, the implant body having a core, along which a helical thread having at least one spiral extends, the dental implant having at least one section, wherein the height of the thread gradually decreases in the direction of the coronal end, and the core gradually tapers in the direction of the apex, the at least one spiral having a top surface oriented toward the apex of the dental implant, a coronal surface oriented toward the coronal end of the dental implant, and a peripheral side surface connecting the top surface and the coronal surface of the at least one spiral. Such a dental implant is described, for example, in document EP 1 624 826. The dental implant typically has a apex, whose cross section is substantially equal to the cross section of the cylindrical hole. During its insertion, the dental implant gradually compresses the bone at the periphery of the hole formed in the bone, so that the primary stability is improved.
[0005] However, when such a dental implant is inserted into a denser bone (generally a density of D1 or D2 according to the Misch classification), the density of the bone makes it less compressible, with the result that penetration of the dental implant requires a much higher screwing torque, sometimes too high to be borne by the dental implant without damage (particularly at its connection means allowing it to be screwed in by a rotational drive).
[0006] Document EP 1 624 826 describes a dental implant according to the preamble of claim 1. The at least one spiral of the dental implant thus comprises an apical surface oriented towards the apex of the dental implant, a coronal surface oriented towards the coronal end of the dental implant and a peripheral side surface connecting the apical surface and the coronal surface of the at least one spiral. The apical surface of the at least one spiral implicitly has a first profile in a cross section along the longitudinal axis of the dental implant that repeats according to the apical distance, while the coronal surface of the at least one spiral implicitly has a second profile in a cross section along the longitudinal axis of the dental implant that repeats according to the coronal distance. However, there is no explicit mention of the apical distance and the coronal distance of the spiral in the context of the present invention in the above document. There is also no mention of any difference that may exist between the apical distance and the coronal distance or of any feature that would have the result of causing a difference between the apical distance and the coronal distance. On the contrary, the apical distance and the coronal distance of the spiral of the above implant seem to be equal. It is also never explained how the above dental implant is manufactured. The same applies to documents US 2008 / 261175, WO 2017 / 129826 and EP 2 570 096. Summary of the invention
[0007] A problem addressed by the present invention is to provide a dental implant which can be inserted into low density bone and compress the bone to obtain a good primary stability and which can be inserted into denser bone without the tightening insertion torque thereby becoming too high.
[0008] To achieve the above and other objects, the present invention provides a dental implant body extending along a longitudinal axis between a coronal end and an apex, the dental implant body having a core, along which a helical thread having at least one thread extends, the dental implant having at least one section in which the height of the thread gradually decreases in the direction of the coronal end and the core gradually tapers in the direction of the apex, the at least one thread having a top surface oriented toward the apex of the dental implant, a coronal surface oriented toward the coronal end of the dental implant, and a peripheral side surface connecting the top surface and the coronal surface of the at least one thread, wherein:
[0009] - the top surface of the at least one spiral has, in a section along the longitudinal axis, a first profile that repeats according to a top distance,
[0010] - the crown surface of at least one spiral has, in a section along the longitudinal axis, a second profile that repeats according to the crown distance,
[0011] The invention is characterized in that, in the at least one section, the top distance is greater than the crown distance.
[0012] In the prior art implants described in documents EP 1 624 826, US 2008 / 261175, WO2017 / 129826 and EP 2 570 096, the crown distance and the apical distance are equal. In the section in which the height of the thread gradually decreases in the direction of the coronal end and the core gradually tapers in the direction of the apex, the width of the peripheral side surface (along the longitudinal axis) of the spiral increases in the direction of the coronal end. As a result, in this section, the thread radially compresses the bone more near the coronal end than near the apex, which significantly increases the screwing torque when the section of the dental implant is inserted into the bone.
[0013] In the dental implant according to the invention, providing a thread with a apical distance greater than a coronal distance in a section in which the thread has a height that gradually decreases in the direction of the coronal end (towards) and in which the core tapers in the direction of the apex leads to a smaller increase in the width of the peripheral side surface (along the longitudinal axis) in the direction of the coronal end. This therefore reduces the screw-in torque.
[0014] In order to facilitate the manufacture of the implant, in a first embodiment, the crown distance and the apical distance may advantageously be constant.
[0015] The apex distance and the crown distance can preferably be selected so that the ratio of the larger to the smaller of the apex distance and the crown distance lies within the interval [1; 1.1]. Thus, good results are obtained in terms of reducing the screwing torque.
[0016] In a second embodiment, one of the crown distance and the apex distance is constant, while the other of the crown distance and the apex distance increases gradually. Thus, the crown distance or the apex distance can be varied so as to obtain a substantially constant width of the peripheral side (along the longitudinal axis) in a section in which the thread has a height that decreases gradually in the direction of the coronal end and in which the core tapers gradually in the direction of the apex.
[0017] For a gradual compression of the bone, the core can advantageously taper in a conical manner in the direction of the tip over the at least one section of the length of the implant.
[0018] In the at least one section of the length of the implant in which the core tapers in the direction of the apex, the thread can advantageously taper in the direction of the apex, preferably in a conical (conical) manner.
[0019] In the at least one section of the length of the implant:
[0020] - the core and the threads are preferably conical,
[0021] The taper of the core is advantageously greater than the taper of the thread.
[0022] According to another aspect, the invention proposes a method for producing 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, characterized in that:
[0023] a) during a first threading cycle, forming at least one spiral by means of a threading tool which is subjected to a longitudinal relative movement according to a first pitch, such that:
[0024] - in at least one section of the dental implant, said at least one spiral has a height which decreases in the direction of the coronal end and the core tapers in the direction of the apical end,
[0025] - said at least one spiral has a coronal surface oriented substantially in the direction of the coronal end,
[0026] - the at least one spiral has a top surface which is oriented substantially in the direction of the apex,
[0027] - said at least one spiral has a peripheral side surface connecting the top surface and the coronal surface,
[0028] b) during a second threading cycle, in said at least one length section of the dental implant, re-cutting with the threading tool with a longitudinal relative movement according to a second pitch:
[0029] - a top surface, wherein the second pitch is greater than the first pitch, and / or
[0030] - A coronal plane, wherein the second pitch is smaller than the first pitch.
[0031] This method makes it possible to obtain a dental implant having a reduced screwing insertion torque relative to a dental implant in which the first and second pitches are equal in said section in which the height of the thread tapers in the coronal direction and in which the core tapers in the apical direction.
[0032] For ease of manufacture, the first and second pitches may advantageously be constant.
[0033] The ratio of the larger to the smaller of the first and second pitches preferably belongs to the interval [1; 1.1].
[0034] The first and second pitches may advantageously be between 0.6 mm and 3 mm. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Other objects, features and advantages of the present invention will become apparent from the following description of specific embodiments given with reference to the accompanying drawings, in which:
[0036] Figure 1is a side view of a particular embodiment of a dental implant according to the invention after a first manufacturing step;
[0037] Figure 2 is a side view of a particular embodiment of a dental implant according to the present invention after a second manufacturing step;
[0038] Figure 3 is a side view of a particular embodiment of a dental implant according to the present invention when it is completed;
[0039] Figure 4 yes Figure 3 A partial longitudinal cross-sectional view of a dental implant; and
[0040] Figure 5 It shows Figure 3 Graph of the insertion torque of a dental implant according to the present invention and a dental implant not according to the present invention. DETAILED DESCRIPTION
[0041] Figure 3 and Figure 4 A particular embodiment of a dental implant 1 according to the invention is shown in FIG.
[0042] 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. The thread 4 here comprises two threads F1 and F2.
[0043] Spirals F1 and F2 respectively include top surfaces SA1 and SA2 oriented toward the apex 2b of the dental implant 1, and coronal surfaces SC1 and SC2 oriented toward the coronal end 2a of the dental implant 1. A peripheral side surface SLP1 connects the top surface SA1 and the coronal surface SC1. A peripheral side surface SLP2 connects the top surface SA2 and the coronal surface SC2.
[0044] The outer shape of the implant body 2 and the outer shape of its core 3 are Figures 1 to 4 This is emphasized more particularly by means of the envelope 5 and the dashed lines of the implant body 2. It can thus be seen that the implant body 2 comprises five continuous (consecutive) segments T1 to T5 from its coronal end 2a to its apical end 2b.
[0045] In section T1, the core 3 is substantially cylindrical (cylindrical), while the thread 4 is conical with a taper directed toward the coronal end 2a. Therefore, the height H of the spirals F1 and F2 (in a plane substantially perpendicular to the longitudinal axis II) decreases in the direction of the coronal end 2a. This gradual reduction of 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 bone ridge of the maxilla or mandible in the vestibular-palatal direction. This enables the aesthetic integration of the dental implant 1.
[0046] In section T2, the core 3 tapers in the direction of the apex 2b, thereby tapering at a taper angle A3 directed towards the apex 2b, while the thread 4 has a substantially cylindrical shape with a constant radius R. Thus, the height H of the spirals F1 and F2 (in a plane substantially perpendicular to the longitudinal axis II) increases gradually in the direction of the apex 2b, while the width L of the peripheral side surfaces SLP1 and SLP2 of the spirals F1 and F2 (along the longitudinal axis) increases gradually in the direction of the coronal end 2a.
[0047] In section T3, the core 3 is also conical. Its taper is the same as in section T2. The thread 4 also tapers in the direction of the tip 2b, thereby presenting a cone with a taper directed towards the tip 2b. The height H of the thread 4 varies depending on the relationship between the respective taper angles A3 and A4 of the core 3 and the thread 4:
[0048] - 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 tip 2b,
[0049] - if the cone angle A3 of the core 3 is equal to the cone angle A4 of the thread 4, the height H of the thread 4 is substantially constant in the direction of the tip 2b,
[0050] 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 tip 2 b .
[0051] In the particular embodiment shown in the figures, 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 tip 2b.
[0052] In section T4, the core 3 is also tapered. Its taper is the same as in sections T2 and T3. The thread 4 itself is also circular.
[0053] Segment T5 is convex, having a semi-lens shape. It is completely optional.
[0054] The core 3 therefore tapers over at least one section of the length of the dental implant 1 , here over the sections T2 to T4 , in the direction of the apex 2 b .
[0055] In section T2, the thread 4 has a height H (along a radial axis perpendicular to the longitudinal axis II) which decreases in the direction of the coronal end 2a. There, the core tapers in the direction of the apex 2b and more specifically has a cone with a cone angle A3. All this is particularly true in Figure 4 As can be seen in the figure, Figure 3 Detailed view of a longitudinal section of a segment T2 of the dental implant 1 .
[0056] In this Figure 4 It can be seen that:
[0057] the top surfaces SA1 and SA2 of the spirals F1 and F2 have, in a section along the longitudinal axis II, first profiles PP1 and PP2 that repeat according to a top distance PA,
[0058] the coronal surfaces SC1 and SC2 of the spirals F1 and F2 have, in section along the longitudinal axis II, second profiles DP1 and DP2 that repeat according to the coronal distance PC,
[0059] - The apex distance PA is greater than the crown distance PC.
[0060] Here the crown distance PC and the vertex distance PA are constant. The ratio of the vertex distance PA to the crown distance PC is in the interval [1; 1.1]. Figure 4 In the example shown, the apex distance PA is 2.03 mm and the crown distance PC is 2 mm. Therefore, the ratio of the apex distance PA to the crown distance PC is more specifically 1.015.
[0061] Alternatively, one of the crown distance PC or the top distance PA may be constant, while the other of the crown distance PC or the top distance PA gradually increases.
[0062] exist Figure 3 As can be seen in the figure, in the section T3, the core 3 tapers in the direction of the apex 2b (more specifically tapers at an angle A3), and the thread 4 also tapers in the direction of the apex 2b, tapers at an angle A4. In order to have a height H of the thread 4 that decreases in the direction of the coronal end 2a (along a radial axis perpendicular to the longitudinal axis II) in the section T3, the core 3 has a greater taper than the taper of the thread 4, that is to say that in practice the angle A3 is greater than the angle A4. In the section T3, the spirals F1 and F2 have the same crown distance PC and apex distance PA characteristics, that is to say the apex distance is greater than the crown distance PC.
[0063] With the help of Figure 1 and 2 Explain more specifically the manufacturing of dental implants.
[0064] exist Figure 1In FIG. 1 , an implant body 2 made according to a first threading cycle can be seen. During this first threading cycle, the helices F1 and F2 are formed by the threading tool in a longitudinal relative movement with a first pitch P1, such that:
[0065] - in sections T2 and T3 of the length of the dental implant 1 , the spirals F1 and F2 have a height H (along a radial axis perpendicular to the longitudinal axis II) which tapers in the direction of the coronal end 2a, and the core 3 tapers in the direction of the apical end 2b,
[0066] - the spirals F1 and F2 comprise respectively coronal surfaces SC1 and SC2 oriented substantially in the direction of the coronal end 2a,
[0067] - the spirals F1 and F2 comprise respectively a top surface SA1 and SA2 oriented substantially in the direction of the apex 2b,
[0068] The spirals F1 and F2 comprise respective peripheral side faces SLP1 and SLP2 , one of which connects the top face SA1 and the coronal face SC1 , and the other of which connects the top face SA2 and the coronal face SC2 .
[0069] In this Figure 1 As can be seen in the figure, in sections T2 and T3, the width L of the peripheral side surfaces SLP1 and SLP2 (in a radial plane containing the longitudinal axis II) increases relatively strongly in the direction of the coronal end 2a. This greatly increases the screwing insertion torque of the dental implant 1 when the sections T2 and T3 are inserted into the bone.
[0070] To arrive Figure 2 In the dental implant 1 , during the second thread machining cycle, in sections T2 and T3 of the length of the dental implant 1 , the top surfaces SA1 and SA2 and / or the coronal surfaces SC1 and SC2 of the threads F1 and F2 are re-cut by the thread machining tool in a longitudinal relative movement at a second pitch P2 different from the first pitch P1.
[0071] More precisely:
[0072] If the second pitch P2 is greater than the first pitch P1, the top surfaces SA1 and SA2 are recut. Therefore, the second pitch P2 is equal to the top distance PA and is greater than the crown distance PC (defined by the crown surfaces SC1 and SC2 that have not been recut, as shown in FIG. Figure 4 A first pitch P1 (shown);
[0073] If the second pitch P2 is smaller than the first pitch P1, the coronal surfaces SC1 and SC2 are recut. Thus, the second pitch P2 is equal to the coronal distance PC and smaller than the first pitch P1 as the apical distance PA (defined by the apical surfaces SA1 and SA2 which are not recut).
[0074] The second threading cycle results in a reduction in the width L (in a radial plane containing the longitudinal axis II) of the peripheral flanks SLP1 and SLP2, which gradually increases in the direction of the coronal end 2a. Figure 1 ) after which the dental implant 1 comprises an increase in the width L (in a radial plane containing the longitudinal axis II) of the peripheral side surfaces SLP1 and SLP2 in the direction of the coronal end 2a.
[0075] exist Figure 2 As can be seen in the figure, in sections T2 and T3, the width L (along the longitudinal axis II) of the peripheral side surfaces SLP1 and SLP2 does not increase as much in the direction of the coronal end 2a as in the Figure 1 This significantly weakens the increase in the insertion torque of the segments T2 and T3 (and therefore the dental implant 1 ) when they penetrate into the bone.
[0076] After the second thread machining cycle, a plurality of tapping grooves, such as grooves R1 and R2 ( Figure 3 ) so that the dental implant 1 has self-tapping capability.
[0077] The effect of the present invention in reducing the screwing insertion torque is Figure 5 , which is shown in a graph showing the insertion torque (in N.cm) as a function of penetration (in mm) performed by inserting two dental implants into a polyurethane biomechanical test block with a density of 40 PCF (pounds per cubic foot) representing high-density bone.
[0078] Curve C1 relates to a similar Figure 1 A dental implant (but further provided with a similar Figure 3 The dental implant has been inserted by screwing it into a hole with an inner diameter of 3.6 mm.
[0079] Curve C2 relates to a 4 mm maximum outer diameter (in section T2) and a total length of 12 mm. Figure 3 The dental implant 1 according to the present invention (having a structure similar to Figure 3 The dental implant has been inserted by screwing it into a hole with an inner diameter of 3.6 mm.
[0080] It can be seen that for a penetration stroke very slightly less than 10 mm, the insertion torque shown by curve C1 increases rapidly to 80 N.cm. The screwing is then interrupted at 80 N.cm in order not to damage the internal connector means of the dental implant so that it can be driven in rotation to screw it in. This actually means that the insertion of the dental implant has failed: it has not been possible to do this in the block over its entire length of 12 mm.
[0081] It can be seen that the insertion torque of the dental implant 1 according to the present invention, shown by curve C2, increases slowly. For a penetration of about 10 mm, the insertion torque is about 50 N.cm, which is much less than 80 N.cm for the implant without the present invention. This successfully inserts the dental implant 1 with its full length of 12 mm without exceeding an insertion torque of 70 N.cm, which is unlikely to damage the internal connector means of the dental implant 1, so that it can be driven in rotation to screw it in.
[0082] Curve C2 has a smaller slope than curve C1 : thanks to the invention, the increase in screw-in torque is greatly attenuated.
[0083] The invention is not limited to the embodiments that have been explicitly described, but includes modifications and generalizations of the invention that are included within the scope of the following claims.
Claims
1. A dental implant (1) comprising an implant body (2) extending along a longitudinal axis (II) between a coronal end (2a) and an apical end (2b), the implant body (2) having a core (3), along which a helical thread (4) having at least one spiral (F1, F2) extends, the dental implant (1) having at least one section (T2, T3) in which the thread (4) has a height (F1, F2) which gradually decreases in the direction of the coronal end (2a). H) and the core (3) tapers in the direction of the apex (2b), the at least one spiral (F1, F2) having an apical surface (SA1, SA2) oriented toward the apex (2b) of the dental implant, a coronal surface (SC1, SC2) oriented toward the coronal end (2a) of the dental implant (1), and a peripheral side surface (SLP1, SLP2) connecting the apical surface (SA1, SA2) and the coronal surface (SC1, SC2) of the at least one spiral (F1, F2), wherein: The top surface (SA1, SA2) of the at least one spiral (F1, F2) has, in a section along the longitudinal axis (II), a first profile (PP1, PP2) that repeats according to a top distance (PA), The coronal surface (SC1, SC2) of at least one spiral (F1, F2) has, in a section along the longitudinal axis (II), a second profile (DP1, DP2) that repeats according to a coronal distance (PC), Characterized in that, in the at least one section (T2, T3), the top distance (PA) is greater than the crown distance (PC).
2. The dental implant (1) according to claim 1, characterized in that The crown distance (PC) and the apex distance (PA) are constant.
3. The dental implant (1) according to claim 2, characterized in that The ratio of the top distance (PA) to the crown distance (PC) belongs to the interval [1, 1.1].
4. The dental implant (1) according to claim 1, characterized in that One of the crown distance (PC) and the top distance (PA) is constant, and the other of the crown distance (PC) and the top distance (PA) gradually increases.
5. The dental implant (1) according to any one of claims 1 to 4, characterized in that The core (3) tapers conically in the direction of the apex (2b) on the at least one section (T2, T3) of the dental implant (1).
6. The dental implant (1) according to claim 5, characterized in that In the at least one section (T2, T3) of the dental implant (1) in which the core (3) tapers in the direction of the apex (2b), the thread (4) tapers, preferably conically, in the direction of the apex (2b).
7. The dental implant (1) according to claim 6, characterized in that In the at least one section (T2, T3) of the dental implant (1): The core (3) and the thread (4) are conical, The taper (A3) of the core (3) is greater than the taper (A4) of the thread (4).
8. A method for producing a dental implant (1), comprising an implant body (2) extending along a longitudinal axis (II) between a coronal end (2a) and an apical end (2b), the implant body (2) having a core (3) along which a helical thread (4) having at least one spiral (F1, F2) extends, characterized in that: a) during a first threading cycle, forming at least one spiral (F1, F2) by means of a threading tool which is subjected to a longitudinal relative movement according to a first pitch (P1), such that: In at least one section (T2, T3) of the dental implant (1), the at least one spiral (F1, F2) has a height (H) which decreases in the direction of the coronal end (2a), and the core (3) tapers in the direction of the apical end (2b), said at least one spiral (F1, F2) having a coronal surface (SC1, SC2) oriented substantially in the direction of said coronal end (2a), The at least one spiral (F1, F2) has a top surface (SA1, SA2) oriented substantially in the direction of the top end (2b), The at least one spiral (F1, F2) has a peripheral side surface (SLP1, SLP2) connecting the top surface (SA1, SA2) and the coronal surface (SC1, SC2), b) during a second thread machining cycle, in said at least one length section (T2, T3) of the dental implant (1), re-cutting using the thread machining tool with a longitudinal relative movement according to a second pitch (P2): the top surface (SA1, SA2), the second pitch (P2) is greater than the first pitch (P1), and / or The coronal plane (SC1, SC2), the second pitch (P2) is smaller than the first pitch (P1).
9. The manufacturing method according to claim 8, characterized in that: The first pitch (P1) and the second pitch (P2) are constant.
10. The manufacturing method according to claim 9, characterized in that: A ratio of a largest one to a smallest one of the first pitch (P1) and the second pitch (P2) belongs to the interval [1, 1.1].
11. The manufacturing method according to any one of claims 8 to 10, characterized in that: The first pitch (P1) and the second pitch (P2) are between 0.6 mm and 3 mm.