Photoelastic Analysis of Fixed Partial Prosthesis Crown Height and Implant Length on Distribution of Stress in Two Dental Implant Systems

Abstract

The aim of this study was to evaluate by photoelastic analysis stress distribution on short and long implants of two dental implant systems with 2-unit implant-supported fixed partial prostheses of 8 mm and 13 mm heights. Sixteen photoelastic models were divided into 4 groups: I: long implant (5 × 11 mm) (Neodent), II: long implant (5 × 11 mm) (Bicon), III: short implant (5 × 6 mm) (Neodent), and IV: short implants (5 × 6 mm) (Bicon). The models were positioned in a circular polariscope associated with a cell load and static axial (0.5 Kgf) and nonaxial load (15°, 0.5 Kgf) were applied to each group for both prosthetic crown heights. Three-way ANOVA was used to compare the factors implant length, crown height, and implant system (α = 0.05). The results showed that implant length was a statistically significant factor for both axial and nonaxial loading. The 13 mm prosthetic crown did not result in statistically significant differences in stress distribution between the implant systems and implant lengths studied, regardless of load type (P > 0.05). It can be concluded that short implants showed higher stress levels than long implants. Implant system and length was not relevant factors when prosthetic crown height were increased.

Stress on external hexagon and Morse taper implants submitted to immediate loading

“…This fact emphasizes the importance of quantitative analysis for photoelastic methodology and the literature suggests that the photoelastic method, associated with a quantitative analysis, is better for comparing stress at the bone-implant interface. [18][19][20] Shear stress values for the distal implant (A/E) showed no statistically significant differences between the infrastructure types, signifying that the bar type is irrelevant for reducing the stress levels around implants. This lack of influence of the bar type is probably due to the total passivity obtained with this technique, since the position of these implants is in accordance with the framework.…”