Photoelastic Analysis of Stresses Transmitted by Implant Supported Adjacent Crowns

Objectives: The aim of this study was evaluate the influence of the proximal contact in the load distribution and stress characteristics in the posterior region of the mandible transmitted by adjacent non-splinted screw-retained over implants metal-ceramic crowns with and without the presence of a second molar proximal contact, using photoelastic analysis.

Methods: A rectangular model (68 x 30 x 15mm) was made of polymethylmethacrylate resin to simulate half of the mandibular arch. The model was completed with resin replicas replacing the first premolar and second molar, and two 3.75 X 11mm threaded implants replacing the second premolar and first molar. Roots of the teeth replicas were covered with an Impregum Soft layer to simulate the periodontal ligament. Different load application points were coupled to the device and the following loads were applied: 1 – single vertical loading on the premolar and molar crowns (5kgf); 2 - simultaneous vertical loading on the crowns replacing the premolar and molar (10kgf). Three points in the cervical area, between the teeth and implants, and one point in apical area of each implant were considered.

Results: Table 1- Stress values (MPa) in the predetermined points of interest

Points of interest	With 2nd molar			Without 2nd molar
	Load application:			Load application:
	Molar	Simultaneous	Premolar	Molar	Simultaneous	Premolar
1	6.28	8.83	6.17	15.75	10.54	2.66
2	1.38	7.13	10.11	5.53	4.58	7.77
3	26.93	22.99	25.33	11.07	20.01	10.54
4	15.65	15.43	4.15	8.2	13.73	4.47
5	4.04	3.51	2.77	3.09	2.43	3.62

 After photoelastic qualitative and quantitative analysis, the results showed that the presence of a second molar proximal contact optimizes the stress distribution around the implants. 

  Conclusions: The presence of effectiveness proximal contact reduces stresses around the implants under vertical static load and that premature occlusal contacts concentrate the stresses around the loaded implant.

This abstract is based on research that was funded entirely or partially by an outside source: FAPESP 2008/06960-8

Keywords: Biomechanics, Implants, Loading, Occlusion and Prosthodontics

Presenting author's disclosure statement: All authors disclose any financial and personal relationships with other people or organizations that could inappropriately influence (bias) this work.

See more of: Implant-supported Prostheses/Imaging Techniques for Host Bone or Interface Evaluation
See more of: Implantology Research

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