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Photoelastic comparison of as-cast and laser-welded implant frameworks
Karina Albino Lencioni1, Ana Paula Macedo2, Renata Cristina Silveira Rodrigues3
1Postgraduate student, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
Statement Of Problem:
A misfit between the implant and metal framework can produce biomechanical problems.
Purpose:
The purpose of this in vitro study was to evaluate the vertical misfit, passivity, and biomechanical behavior of a prosthetic protocol-shaped I-beam framework, varying the number and inclination of implants before and after laser welding.
Material And Methods:
Two metal models with 4 or 5 implants were used. The I-beam framework for 4 or 5 implants was fabricated with cobalt-chromium alloy. The vertical misfit and passivity were evaluated with a stereomicroscope at ×80 magnification, with frameworks screwed into the respective model. The biomechanical behavior was analyzed with photoelastic studies. These analyses were performed before and after welding to observe the influence of the laser welding.
Results:
The misfit was not significantly different among the groups studied; laser welding did not influence the vertical misfit. However, when the groups were compared for passivity, the 5 implants before welding group were statistically different (P=.025).
Conclusions:
Laser welding generated more passivity, less vertical misfit, and favorable stress distribution to the I-beam framework supported by 4 implants. To the I-beam framework supported by 5 implants laser welding did not influence the misfit or stress distribution, but there was an improvement in passivity.
