Análise fotoelástica da distribuição das tensões em próteses unitárias e de três elementos implantossuportadas com diferentes tipos de conexões internas

Abstract

The accurate fit between the dental implant and the prosthetic abutment is responsible for the stability of the entire prosthetic-implant system, and provides better distribution of the occlusal load to the surrounding bone. In order to improve the stress distribution between implant and bone, different types of internal connection implants were introduced. However, there are few studies on the biomechanical behavior of these type of connections. This study aimed to investigate the stress distribution in screwed implant-supported prosthesis with different implantabutment connections by using a photoelastic analysis. Eight photoelastic models were fabricated in PL-2 resin and divided according to the different types of internal connections: morse taper (MT), internal morse hexagon (IMH), morse taper hexagon (MTH) and frictional morse taper (FMT) implants (3.75 x 11.5 mm), and the number of crowns (single and 3-unit piece). Models were positioned in a circular polariscope and 100-N axial and oblique (45 degrees) loads were applied in the occlusal surface of the crowns by using a universal testing machine. The stresses were photographically recorded and qualitatively analyzed using a software (Adobe Photoshop). Under axial loading, the number and distribution of high-intensity fringes did not differ among groups for both crowns types (single and splinted 3-element). Low stress values located at the implant apex were noted. The oblique loading increased the number of fringes for all groups. In conclusion, the internal connection tested in this study did not affect the number and distribution of stress. The different types of internal connection provided better stability of the implant/prosthesis set, which provides improved stress distribution when the prosthetic pillar is loaded. Oblique loading promoted higher stress concentration than axial loading