Stress Distribution Around Single Short Dental Implants: A Finite Element Study

Abstract

Bone height restrictions are more common in the posterior regions of the mandible, because of either bone resorption resulting from tooth loss or even anatomic limitations, such as the position of the inferior alveolar nerve. In situations where adequate bone height is not available in the posterior mandible region, smaller lengths of implants may have to be used but it has been reported that the use of long implants (length ≥10 mm) is a positive factor in osseointegration and authors have reported failures with short implants. Hence knowledge about the stress generated on the bone with different lengths of implants needs scientific evaluation. The purpose of this study was to compare and evaluate the influence of different lengths of implants on stress upon bone in mandibular posterior area. A 3 D finite element model was made of the posterior mandible using the details from a CT scan, using computer software (ANSYS 12). Four simulated implants with lengths 6 mm, 8 mm, 10 mm and 13 mm were placed in the centre of the bone. A static vertical force of 250 N and a static horizontal force of 100 N were applied. The stress generated in the cortical and cancellous bone around the implant were recorded and evaluated with the help of ANSYS. In this study, Von Mises stress on a 6 mm implant under a static vertical load of 250 N appeared to be almost in the same range of 8 and 10 mm implant which were more as compared to 13 mm implant. Von Mises stress on a 6mm implant under a static horizontal load of 100 N appeared to be less when compared to 8, 10 and 13 mm implants. From the results obtained it may be inferred that under static horizontal loading conditions, shorter implants receive lesser load and thus may tend to transfer more stresses to the surrounding bone. While under static vertical loading the shorter implants bear more loads and comparatively transmit lesser load to the surrounding bone.

The Prosthetic Influence and Biomechanics on Peri-Implant Strain: a Systematic Literature Review of Finite Element Studies

“…Assessing the effect of the axial force, was detected the distribution of uniform stress in peri-implant bone without concentrations in a specific surface area of the implant [24,25,27,28,36]. These FEA findings are close to results of in vivo studies.…”

“…Also, implant design characteristics were described as factors causing the stress. The alteration of stress was related with implant length [21,24,29], width [21,25,26,28-31], macro-relief as thread [28,32], and micro-relief as porosity [27]. Some of the articles emphasized that stress changes were caused by platform switching connection [20-22,33].…”

Effect of joining the sectioned implant-supported prosthesis on the peri-implant strain generated in simulated mandibular model

“…Heat-cured resin was used for fabricating the models as its modulus of elasticity is closer to natural cancellous bone. [ 9 10 11 ] The models were designed with a slit in the center of the base to simulate the L-shape and the flexion of the mandible. Implant analogs of dimension 3.75 mm × 11.5 mm were placed in the following tooth positions; 36, 33, 43, 46.…”

Influence of implant dimensions in the resorbed and bone augmented mandible: A finite element study

“…Many current in vivo and in vitro studies have tried to assess the impact of implant dimensions on the stress transmitted to the peri-implant tissue but have yet to reach a clear conclusion on this complex matter. [ 4 5 6 7 8 ] Some studies have reported that a larger implant may lead to smaller stress values in the peri-implant bone. [ 5 6 7 ] However, other studies show that smaller implants used in resorbed mandibles have a comparable long-term survival rate and stress values to larger implants.…”

“…[ 4 5 6 7 8 ] Some studies have reported that a larger implant may lead to smaller stress values in the peri-implant bone. [ 5 6 7 ] However, other studies show that smaller implants used in resorbed mandibles have a comparable long-term survival rate and stress values to larger implants. [ 4 5 6 ] Furthermore, there is a lack of studies on the importance of bone geometry and its influence on the implant induced stress at the crestal bone level, since implant dimensions, stress, and bone geometry are all inter-related and should not be studied separately.…”