Dental distribution around the peri-implant bone interface with increasAlso

Dental implants have proven to be a
very successful treatment modality in restoration of both partial and complete
edentulous jaws. However, there are still minor part of implant cases failing
primarily due to infection and secondarily to
biological parameters such as length, diameter and the angle at which the
implants are placed. When it comes to the angulation, it is sometimes related
to procedural errors and in other cases it was done intentionally to gain more
surface area and maintain patency of vital structures.7

The major factors that effect when an implant is
placed at an angulation are the abutment gaps and stress distribution after the
loading phase. As a general rule, implants placed vertically receive
compressive (occlusal) and moderate (lateral) shear forces directing most of
them to the apical third. Whereas in case of angulated implants these normal
forces might lead to uneven stress distribution. There are studies indicating
the rationale for use of titled implants and possible failure and success
ratios. But none have addressed the area of where and how much maximum tilt is
survivable. Our attempt is to study the stress distribution around the
peri-implant bone interface with increasAlso in our study weSpecific Aims:

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1.      To study the stress distribution
along implant-bone interface when implants placed at different angulations.
Number of angulation 10,15,20,30,40,50.

2.      Extend study to Mohr’s circle of 3D
Stress analysis for angulated implants in Type 1 to Type 4 bone types (Misch
Classification based on bone density).

3.      To study on stress distribution on
posterior tilted implants with and without anterior axial implant splinting.


Over the
last decade, implants have proven to be successful with an excellent prognostic
factor in restoring edentulous areas. But, still there are a considerable
number of studies showing a small percentage of failing implants. These
failures are classified into early and late failures, where early are during
surgical phase and primary stability attainment. Late failures are those that
arrive after restorative phase.4 Majority of late failures are
attributed to biomechanical overload.4 

are the mainstream of restorative dentistry in the world. One of the main
benefits of placing an implant is to maintain the bone level and esthetics
after the tooth extraction.7 In addition, implant will also increase
the retention, function, and performance of removable restorations for
edentulous patient.7 Ideally, Implant will be placed vertically (0
Degree) to allow the occlusal forces to travel along the long axis of the
tooth.8 In exceptional cases, where there is not enough bone
available to place implant vertically, angulated implant placement for the long
term success.8 Simultaneously, the failure of the implant has been
seen in vertical or angulated implants.9 Out of many indicating
factors for the implant failure, —————- and ————- are the
most common.9

We know
that, when not enough bone present and avoid the damage to vital structure,
angulated implants are best option.8 but we do not have enough
evidence to provide best result in which angulation. Moreover, what is the
range to withstand the forces and for how long? This project has tried to
include these key points to identify the strength of the angulated implants
with the use of Finite Element Analysis (FEA). “FEA were performed for various
angled dental implant to study effects on stress distribution generated in the
surrounding jaw bone and to determine an optimal angulation for even stress
distribution.” 10  

FE analysis
is a virtual 3D application, that is excelling in mechanical engineering to
study solid- solid and solid-liquid interactions. There is old literature in
implant dentistry showing that this software had given reliable results in
studying the stress distribution in the peri-implant area.


















Materials and Methods:

As an initial attempt we proposed to
use Straumann 4.0mm wide, Regular neck, both cylindrical and tapered bone level
implants dimensions. 3D patient scans are obtained from UB SDM, which will be cleared
through IRB approval. The study will be performed in UB-SDM, Dr.Andreana
Implant Research lab with support of Dr. Andreana. We will work in the
combination of Mr.Abani Kumar Patra  from UB- Department of
Mechanical and Aerospace Engineering who is specialized in computational
mathematics and FE Analysis.


The study will follow the guidelines
similar to a solid- solid interaction 3D FE Analysis. The 3D patient scan data
and the Straumann implant dimensional data is loaded into the 3D FE
application. This allows the application to generate 3D virtual patient jaw and
implant structure identical to the natural anatomy and dimensions. The
application also allows us to load the density of the solids, which helps us to
load the densities of type 1- 4 bone and the implant density. The application
generates the resistance based on the densities loaded. This allows us to map
the Poison’s ratio along the implant-bone interface in different bone types.

In total the study involves 8 virtual
models, 4 representing the type 1 – 4 bone type with a Straumann 4.0mm, RN,
cylindrical bone level and other 4 models with similar bone densities with a
tapered implant.

Once the 8 models were generated a
simulation exercise similar to the bite forces will be applied to the implant.
The forces will be applied starting from 500- 2000 N compressive and 150 N
lateral force representing the normal occlusal and shear forces in human. 11
The results are drawn using different variable ratios and will be mapped
accordingly to show the stress distribution.

Statistical Management of Data:



























Yang Zhang, Dan Zhang, Cuijuan Feng, Peng Peng,
Hailong Hu, Toshiyuki Kawakami, Tohru Takagi, Noriyuki Nagai, A
Three-dimensional Finite Element Analysis for the Biomechanical Characteristics
of Orthodontic Anchorage Micro-implant, Journal of Hard Tissue Biology,
Released November 22, 2006, Online ISSN