WO2021001848A1

WO2021001848A1 - An apparatus for basal anchor dental implant having threading profile of cortical threads and cancellous threads

Info

Publication number: WO2021001848A1
Application number: PCT/IN2020/050565
Authority: WO
Inventors: Jayendra Bhupendrabhai DIWAN
Original assignee: Diwan Jayendra Bhupendrabhai
Priority date: 2019-06-30
Filing date: 2020-06-30
Publication date: 2021-01-07

Abstract

: An apparatus for basal anchor dental implant having threading profile of cortical threads and cancellous threads discloses an apparatus for dental implant. More particularly for basal screw dental implant wherein basal screw is provided onto an apparatus consisting of cortical threads and cancellous threads. the present invention solves the problem by proving an apparatus wherein two different thread profiles that promotes load shearing, Effective corticalization of cancellous bone and better stress relieving and distribution. The present invention provides a screw that has maximum stability, less shear stress and ultimately lesser chances of implant failure or implant loosening.

Description

TITLE AN APPARATUS FOR BASAL ANCHOR DENTAL IMPLANT HAVING THREADING PROFILE OF CORTICAL THREADS AND CANCELLOUS THREADS.

FIELD OF THE INVENTION:

The present invention relates to dental implants which can replace missing teeth and restore masticatory function. The present invention relates more particularly to basal type of dental implant wherein basal screw utilizes the basal cortical portion of the jaw bones for retention. This cortical bone is hard bone and can bear high occlusal load without being resorbed. It can be loaded immediately means restore masticatory function within few days, can be placed in the atrophied or normal jawbone.

BACK GROUND OF THE INVENTION:

Dental implants are often the best treatment for missing teeth. When a damaged or decayed tooth is removed, both the visible part of the tooth called the crown and the root are lost.

Conventionally, most common methods for dental implants are two step dental implant procedures have become standard in dentistry in the last two decades and also restore the patient’s mastication function. The long term success or failure of an implant is determined by the manner how the stresses at the bone-implant interface are transferred to the surrounding bones. And stability of implant abutment interface against mechanical loads (compression, bending, tension, torsion loads) acting on a prosthetic implant abutment system during functional and para functional activities.

One such method discloses in US 6848907 that is related to a screw for dental implants. Wherein a screw set for dental implants including a plurality of dental-implant screws but problem arises in such implants is progressive loosening of the screws connecting the implant with abutment and fracture of such screw or whole implant. Further, the screws used in general implants needs to be tightened with shear force because of which the damage of bone becomes normal difficulty. Also, by day to day operation it is observed that the screws get loose and because of which patients may face difficulties.

US patent publication number US20130216976 discloses basal implants are specifically designed single piece screw implant that utilizes strong cortical bone of the jaw to anchorage no threads anchor in alveolar ridge. It has single thread profile which is sharp and deep. The limitation of this invention is its sharp & deep thread profile creates high shear stress under loading condition of masticatory function. Bone is weakest in shear force and high shear force leads to implant failure. One familiar example of high shear stress is that we can easily cut an apple with the sharp knife and it is very difficult to cut an apple very blunt knife.

Another method described in US 8623060. It particularly discloses sharp & deep thread profile & cannulated screw for orthopaedic application. Screw have more deeply cut and more widely spaced threads compared to cortical screw. Since cancellous bone is much less dense than cortical bone the screw threads cut their path in the bone when the screw is inserted. Same phenomena of screw failure is observed in orthopaedics, under loading condition high shear force leads bone resorption.

In the both of the screws have similar thread pattern is deep and sharp, Large thin and polished shaft but head design is different. Under loading condition sharp and deep thread pattern creates higher shear force surrounding bone this results bone resorption, screw loosening and screw migration. Moreover, the conventional screw for dental implants exhibits several further disadvantages such as when inserted in the penetration hole of the dental prosthesis, the screw is difficult to locate visually, which hinders manipulation of the screw; if the surrounding portions of the recess of the screw become dull, the screw can be untightened only after breaking down the dental prosthesis, which necessitates remaking the dental prosthesis; the reduction of the clamping force of a tightened screw, due to the normal masticatory operation of the dental prosthesis, results in a loosening of the dental prosthesis, allowing undue movement; and a repetitive manipulation of the screw, e.g., tightening and untightening, is required for regular cleaning of the fitted dental prosthesis, but in retightening the screw, after a cleaning operation, the required clamping force is difficult to achieve if the tightening and untightening have been performed by compulsion, such that the surrounding portions of the recess of the screw become dull.

So, the present invention solves the problem by proving an apparatus wherein two different thread profiles that promotes load shearing, Effective Corticalization of cancellous bone and better stress relieving and distribution. The present invention provides a screw that has maximum stability, less shear stress and ultimately lesser chances of implant failure or implant loosening.

SUMMARY OF THE INVENTION:

An apparatus for basal anchor dental implant having threading profile of cortical threads and cancellous threads comprising two types of thread profiles i.e., cortical thread and cancellous thread. Cortical threads are at distal region of implant that engages in cortical bone. Cortical threads have deep and sharp thread angle which allows threads to wedge easily in hard cortical bone. Cortical bone is less likely to resorb under dynamic loading condition and most of the occlusion forces are grounded to hard cortical bone. Cancellous threads are at superior region to cortical threads that engages in cancellous bone in alveolar region. Cancellous thread is a combination of two threads, Base thread and top thread which is smaller sharp thread formed upon the top of base thread. Base thread has 3 distinct features. Minor thread diameter is bigger than cortical thread, threads are broader and shallower than cortical tread and conical thread profile. These threads are needed to achieve Effective cortecalization of cencellous bone. It takes active part in load sharing and prevent overloading of hard cortical bone and prevents implant failure and helpful in stress relieving and distribution.

The principal object of the present invention is to provide an apparatus for dental implant. More particularly for basal screw dental implant wherein basal screw is provided onto an apparatus consisting amalgamation of cortical threads and cancellous threads.

One of the objects of the present invention is to provide an apparatus of basal type dental implant consisting of cortical threads wherein Cortical threads comprises deep and sharp thread angle which allows threads to wedge easily in hard cortical bone.

One of the objects of the present invention is to provide an apparatus of basal type dental implant consisting of cancellous threads is amalgamation of base thread and top thread.

One of the objects of the present invention is to provide cancellous threads prevents overloading of hard cortical bone, implant failure and helpful in stress relieving and stress distribution.

One of the objects of the present invention is to provide large anchoring region by providing amalgamation of cortical thread and cancellous thread region on an apparatus.

One of the objects of the present invention is to provide better shear stress distribution under dynamic loading. As broad and shallow cancellous threads transfer less shear force under the dynamic loading.

One of the objects of the present invention is to promote better implant primary postoperative stability (immediate after surgery) and secondary stability (long term), the purpose is to minimise the chances of implant failure or implant loosening.

BRIEF DESCRIPTION OF THE DRAWINGS: The objects, features and advantages of the invention will best be understood from the following description of various embodiments thereof, selected for purposes of illustration, and shown in the accompanying figures.

Figure 1. Illustrate perspective view of an apparatus for basal anchor dental implant having threading profile of cortical threads and cancellous threads.

Figure 2. Discloses an apparatus for basal anchor dental implant wherein cortical threads that engage in cortical bone and cancellous thread that engage in cancellous Bone after final fixation.

Figure 3. Discloses terminology of cortical threads.

Figure 4. Discloses terminology of cancellous threads.

Figure 5. Teaches difference between cancellous thread and cortical threads in terms of diameter of the apparatus.

Figure 6. Teaches difference between cancellous thread and cortical threads in terms of thread size of the apparatus.

Figure 7. Discloses cancellous threads has conical thread profile.

Figure 8. Discloses cancellous thread is a combination of two threads.

Figure 9. Discloses an apparatus having thin polished shaft at superior region to cancellous thread.

Figure 10. Discloses an apparatus having collar which is located on the thin polished shaft.

Figure 11. Discloses the top part of an apparatus which is Abutment.

DETAILED DESCRIPTION OF THE INVENTION:

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompany drawings. The invention is capable of other embodiments, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.

The present invention solves the problem related to the stresses at the bone-implant interface are transferred to the surrounding bones, loosening of the screws connecting the implant with abutment and fracture of such screw or whole implant.

The main embodiment of the present invention is to provide an apparatus for dental implant and particularly for basal screw dental implant wherein basal screw is provided onto an apparatus consisting of cortical threads and cancellous threads. Basal screw dental implant defines as derive support from the basal bone area which is usually remains free from the infection and less prone to resorption.

One of the embodiments of the present invention is to provide an apparatus having amalgamation of cortical threads and cancellous threads. Cortical screws have closely- spaced, shallow threads and larger core-to-outer diameter ratios than cancellous screws. Cortical screws are stronger than cancellous screws of the same outer diameter. They are usually blunt ended. When used to fix plates to long bones, fully-threaded screws are used in order to fixate both cortices so that maximal stability is achieved. The blunt end should extend only a few millimetres into the soft tissues beyond the far cortex to minimize damage to the soft tissue. Cancellous screws are designed for fixation of cancellous bone. They are most commonly used in the metaphysis of long bones where cancellous bone is abundant. They have more deeply cut and more widely spaced threads compared to cortical screw. Since cancellous bone is much less dense than cortical bone, the screw threads cut their path in the bone when the screw is inserted, i.e. cancellous screws are self-tapping. It may partially threaded cancellous screws are often used as lag screws for metaphyseal fractures. One of the embodiments of the present invention is to provide an apparatus of basal screw dental implant consisting of cortical threads wherein Cortical threads comprises deep and sharp thread angle which allows threads to wedge easily in hard cortical bone.

One of the embodiments of the present invention is to provide an apparatus of basal type dental implant consisting of cancellous threads is amalgamation of base thread and top thread. The top thread is small sharp thread formed upon the base thread.

One of the embodiments of the present invention is to provide cancellous threads prevents overloading of hard cortical bone, implant failure and helpful in stress relieving and stress distribution.

Another embodiment of the present invention is to achieve effective cartelization of cancellous bone wherein the process of screw insertion porous cancellous bone surrounded to cancellous thread is compressed and condensed.

One of the embodiments of the present invention is to provide large anchoring region by providing amalgamation of cortical thread and cancellous thread region on an apparatus.

One of the embodiments of the present invention is to provide better shear stress distribution under dynamic loading.

Figure 1 of the present invention illustrate perspective view of an apparatus for basal anchor dental implant having threading profile of cortical threads and cancellous threads. Normally, the whole apparatus is a single piece but the present invention does not limit the scope by providing only single piece but it can be manufactured in different parts as per requirements. As disclosed in Figure 2, an apparatus for basal anchor dental implant having two thread profile as cortical threads 2a that is engaged with cortical bone 2b of jaw of homo-sapiens and cancellous thread 2c is engaged with cancellous bone 2d of jaw of homo- sapiens. Moreover, a thin polished shaft 2e is located above cancellous thread 2c and collar 2g is located on the thin polished shaft 2e at any distance. Abutment 2f is provided to install a tooth on it.

Figure 3 discloses terminology of cortical threads wherein Cortical threads have deep and sharp cortical thread angle 3a is between 20° to 60°. Cortical thread minor diameter 3b is in range between 0.5 mm to 2 mm and it may change as per requirement. Cortical thread major diameter 3c is in range between 2.5mm to 5 mm and it may change as per requirement. Cortical thread having conical profile 3d is 1.4° as suitable but it can vary as per requirement. Cortical thread length 3e is defined as per requirement.

Figure 4 discloses terminology of cancellous threads wherein having cancellous threads at superior region to cortical threads. Cancellous thread is a combination of two threads which are Base thread 4a and top thread 4b which is small sharp thread formed upon the base thread. Cancellous thread angle 4c is in range between 120° to 160° and it may vary as per requirement. Minor diameter 4d of cancellous thread is in range of 2.5mm to 5mm and major diameter 4e having a range of 3mm to 8mm and both are varied as per requirement. Conical profile 4f of cancellous thread is normally same as cortical thread but it may vary as per requirement. Thread length 4g of the cancellous thread is dimensioned as per requirement. Figure 5 teaches difference between cancellous thread and cortical threads in terms of diameter of the apparatus wherein major diameter 5a of cancellous thread is bigger than major diameter 5b of cortical thread. Figure 6 teaches difference between cancellous thread and cortical threads in terms of thread size of the apparatus wherein cancellous threads are broader and shallower 6a than cortical thread 6b. Figure 7 discloses cancellous threads has conical thread profile 7a. Figure 8 discloses cancellous thread is a combination of two threads wherein base thread 8a and top thread 8b which is small sharp thread formed upon the base thread 8a whereas cortical thread has single thread profile 8c. Figure 9 discloses an apparatus having thin polished shaft 9a length of a range between 15mm to 20mm as per requirement and diameter 9b depends upon the diameter of thin polished shaft. Figure 10 discloses an apparatus having collar which is located on the thin polished shaft having length 10a varies between 2mm to 3mm and collar diameter 10b is larger than the diameter of thin polished shaft. Said collar located at the distance 10c from the abutment end as per requirement. Figure 11 discloses a top part of an apparatus which is Abutment wherein diameter 11a of said abutment is varied between 3.5mm to 4.5mm and length lib is in range between 3mm to 7mm. Moreover, distal radius 11c of abutment depends on the diameter of thin polished shaft and abutment.

One of the embodiments of the present invention is to provide effective cortecalization wherein Effective cortecalization of cancellous bone is resulted by chain of action. As the process of screw insertion, first cortical thread 2a are comes in a contact with cancellous bone 2d, bone is displaced according to sharp and deep thread pattern 3a, this formed pattern is further expanding and bone is compressed at 3 points when comes in the contact with cancellous thread.

i. First point of bone compression achieved at base of cancellous thread because its minor thread diameter 5a is bigger than cortical thread 5b.

ii. The sharp and deep cavity that was originally formed by cortical thread is now broadened by cancellous thread because its thread profile is broader 6a than cortical tread 6b.

iii. Finally, conical thread profile 7a expands the cancellous bone because threads major and minor diameter increases as a screw progress in the cancellous bone. Conical thread profile has another advantage that is every thread remains in full contact with bone after final fixation.

iv. As we know that cancellous thread is a combination of two threads, Base thread

4a and top thread 4b which is small sharp thread formed on the top of base thread. This top thread is formed to increase grip of cancellous thread in the cortecalization cancellous bone.

The implant of the present invention wherein bone behaviour in dynamic occlusal loading: i. Cortical bone is less likely to resorb under dynamic loading condition. Cortical thread allows more bone between two threads that promotes good stability in cortical region. Most of the occlusion forces are grounded to hard cortical bone.

ii. Load sharing is done by cortecalization cancellous bone at cancellous thread region the purpose is to achieve load sharing and prevent overloading of hard cortical bone and prevents implant failure.

iii. The region of anchoring is cortical bone and cortecalization cancellous bone. .

This prevents implant loosening & implant mobility.

iv. We all know we can easily cut an apple with the sharp knife and it is very difficult to cut an apple very blunt knife, here shear force principal applies. Bone is weakest in shear force and broad and shallow cancellous threads transfer less shear force under dynamic loading. Thus, cortecalization cancellous bone also prevented from overloading.

v. More stable basal anchor implant, load distribution in larger surface area, Effective cortecalization of cancellous bone, stress relieving and distribution principal applied to prevent bone resorption and implant failure, Patient centric approach.

Experimental Results

Bonenkar Implant’s holding strength test is the important factor to determine implant’s initial stability where there is a comparison of basal anchor dental implant having threading profile of cortical threads and cancellous threads initial stability with other implants in bone Simulation Models.

The material of choice for the Bone Simulation is taken as solid foam high density Saw bone, this product of saw bone mimics Grade 1 bone. Closed cell foam conforms to ASTM F- 1839-08 Standard that has high density 50 pound per cubic feet, volume fraction 0.68 and compressive strength 48megapascal.The uniformity and consistent properties of rigid foam make it an ideal material for comparative testing of bone screws. Place the implant in the bone model according to drilling protocol. After Implant’ s threads are engaged in the bone, abutment is fixed in to abutment holding fixture.

For the experiment, we have used Universal Testing Machine- FIE make UTE -60. Abutment holding fixture is fixed at top Pneumatic grip of the machine and bone model is fixed at bottom Pneumatic grip of the machine. The force is applied in the opposite direction which means machine applies tension force to pull implant out of the bone and peak load was recorded on the software until failure of bone or implant is observed.

Results

Observation

Basal implant peak load is taken as 2.26 KN = 2260 N = 226 Kg

Other single thread profile basal implant peak load is taken as 1.6 KN = 1600 N = 160 Kg

Basal implants holding strength test result

Basal implants initial stability is 40% higher comparing to any other thread profile basal implant.

Claims

CLAIMS We Claim,

[CLAIM 1] An apparatus for basal anchor dental implant 100 having threading profile of cortical threads and cancellous threads is characterised by:

a) cortical thread 2a comprises cortical thread minor diameter

3b, cortical thread major diameter 3c , cortical single thread profile 8c and cortical thread length 3e ;

b) cancellous thread 2c comprises cancellous thread minor diameter 4b, cancellous thread major diameter 4c, cancellous base thread 8a , cancellous top thread 8b and cancellous thread length 4e;

c) protuberant collar 2g connecting the vault end 2f and the thin polished shaft 2e ;

d) vault end 2f comprises vault diameter 11a, vault length lib and vault distal radius 11c;

e) protuberant collar 2g comprises protuberant collar length

10a, protuberant collar diameter 10b and protuberant distance from vault end 10c and

f) thin polished shaft 2e comprises thin polished shaft length

9a and thin polished shaft diameter 9b.

[CLAIM 2] The apparatus as claimed in claim 1, wherein basal screw is an amalgamation of cortical thread 2a and cancellous thread 2c.

[CLAIM 3] The apparatus as claimed in claim 1, wherein the cortical thread angle 3a is having the sharper thread angle 3a ranging from 20^° to 60^°.

[CLAIM 4] The apparatus as claimed in claim 1, wherein the cancellous thread angle 4c is having the blunt Whitworth form ranging from 120^° to 160^°.

[CLAIM 5] The apparatus as claimed in claim 1, wherein cortical thread minor diameter 3b and cortical thread major diameter 3c are forming the cortical thread conical profile 3d ranging from 1.0^° to 2.0°.

[CLAIM 6] The apparatus as claimed in claim 1, wherein cancellous thread minor diameter 4b and cancellous thread major diameter 4c are forming the cancellous thread conical profile 4c ranging from 130^° to 140^°.

[CLAIM 7] The apparatus as claimed in claim 1 wherein the cortical thread

2a and cancellous thread 2c actively occupy the surrounding bone through which the said dental implant 100 is having better holding capacity.

[CLAIM 8] The apparatus as claimed in claim 1, wherein the more surface area has been covered and thread to bone ratio is maintained.

[CLAIM 9] The apparatus as claimed in claim 1, wherein the vault end 2f

supporting the implant comprising the vault groove for the proper bonding of the implant.

[CLAIM 10] The apparatus as claimed in claim 1, wherein the proper maintenance of the thread to bone ratio will endorse to the high primary stability without the cracking or splitting of the bone.

[CLAIM 11] The apparatus as claimed in claim 1 wherein, the occlusion forces are grounded to hard cortical bone 2b and Load sharing is done by corticalized cancellous bone 2d at cancellous thread region.

[CLAIM 12] The apparatus as claimed in claim 1, wherein load sharing is achieved by corticalized cancellous bone 2d.

[CLAIM 13] The apparatus as claimed in claim 1, prevents the implant failure and the mechanical overloading of the bone.

[CLAIM 14] A modified Pross single piece compressive dental Implant 100 as claimed in claim 1 wherein the protuberant collar 2g is less susceptible to the bacterial accumulation.