Overdentures biomechanics' behavior retained by one or two implants with morse taper connection, submitted to traction forces (vertical, anterior and posterior displacement): photoelastic and strain gauge analysis

Abstract

The two implant-retained overdentures have been considered the optimal choice to rehabilitate edentulous jaws. Despite this, recent studies relate the use of a single implant in the middle of the jaw it is sufficient to promote retention and stability to the prosthesis. However, there is no studies with this protocol using morse taper implants. In this way, the present study will aim to evaluate, by photoelastic and strain gauge analysis, the biomechanics' behavior of overdentures implant-retained by one or two morse taper implants, subject to traction forces (vertical, anterior and posterior displacement). From an experimental model of edentulous mandible, the specimens will be divided in 02 groups of 01 sample each to photoelastic analysis and 02 groups of 05 samples each to strain gauge analysis. 12 models will be prepared, 2 with photoelastic resin (PL-2) and 10 with polyurethane resin (F160). These will be divided accord by the number of implants (one or two). On the photoelastic test, the conjunct photoelastic model/implant/prosthesis will be positioned in a circular polariscope and, then, the prosthesis will be pulled in a constant speed of 50mm/min, to simulate the generated tension on the implant/bone interface when the prosthesis is removed. Three types of displacements will be carry out: vertical, anterior and posterior displacement, with a universal testing machine. The generated tensions will be photographically registered and analyzed in a graphical program (Adobe Photoshop), to verify the direction of propagation and the intensity of the tensions, according qualitative analysis. To the strain gauge methodology, two electrical strain gauges will be horizontally positioned in mesial and distal regions of the implants directly on the marginal crest of polyurethane models. The same displacement tests will be carry out. The electrical signs will be captured by a data acquisition device controlled by a computer, being processed by a specific software. Each test will be realized 5 times and the tension values noted, whereas in each test will be expected to reset the tensions values to verify the absence of plastic deformation. The means of tensions values registered will be united in tables and submitted to statistical analysis.