Influência do contato interproximal em próteses fixas implanto-suportadas na mandíbula edentada posterior análise fotoelástica

Abstract

The use of fixed partial dentures in rehabilitations of edentulous jaw with implants is a well documented fact, although controversies still exists about splinting or not prosthetic crowns in these conditions. Thus, the aim of this study was to analyze the effect of prosthetic crowns detachment of a fixed partial denture with surface and punctual contacts by means of stress gradient evaluation determined by the technique of plane transmission photoelasticity. Three photoelastic models were created with 3 contiguous implants corresponding to posterior jaw aligned in straight line, varying the contact between the crowns (contact point = PC; contact surface = SC; splinted = ES). Three loading types were applied: a = axial in group (30 N); b = lateral with a 40º angle (10.8 N) over the implant corresponding to the first molar; c = central axial (9.8 N) over the implant corresponding to the second premolar. Thirty images were obtained of each loading type in each group (n = 270) in the circular polariscope. Fringe orders and maximum shear stress (&#964;) values were obtained by the program Fringes by means of photoelastic analysis of 27 points of each image and right away of 12 points in bone crest region. It was carried out the t-Student test with p<0.05 and the calculation of the graphics area. The majority of the points presented statistically different (p<0.05) in different groups. The ES group presented minimum stress values in all loadings. The SC group showed more homogeneous stress distribution around the implants in all loadings and minimum stress values in the bone crest region when compared to the PC group. Within the limitations of this study, the ES group presented better results, followed by the SC group.