Stress distribution around implants with different interproximal contacts: A photoelastic analysis

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 using the plane transmission photoelasticity technique. Three photoelastic models were created with three adjacent implants corresponding to posterior jaw aligned in straight line, varying the contact between the crowns (contact point = CP; contact surface = CS; splinted = SP). Three loading types were applied: a = axial (30 N); b = lateral with a 40° 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 (τ) values were obtained by the program "Fringes" by means of photoelastic analysis of 27 points of each image. It was carried out the t-Student test with p<0.05 and using normalize points. The majority of the points presented statistically different (p<0.05) in different groups. The SP group presented minimum stress values in all loadings. The CS group showed more homogeneous stress distribution around the implants in all loadings when compared to the CP group. © 2009 Springer-Verlag.