Effect of emergence profile and space gap size on excess cement in cement-retained implant reconstructions

Excess cement is one of the most prevalent problems with cement-retained implant-supported prostheses. The excess cement may be considered an important source of inflammation during implant application. Optimizing the design procedure for reducing excess cement is necessary for successful and safe implant applications.

This study assessed the effect of two confounding factors, i.e., emergence profile and space gap size, on the level of excess cement. Three types of emergence profiles (concave, convex, and straight) and three different gap sizes (30, 60, and 90 µm) were considered for implant design, and the level of excess cement was measured for each design.

Statistical analyses using one-way ANOVA followed by post hoc P value correction revealed that the best emergence profile with the lowest excess cement was the straight profile, with statistically lower excess cement compared with concave and convex profiles (P<0.05) and no significant difference between concave and convex profiles. Furthermore, analyses showed that lower gap size was associated with lower excess cement, even though increasing the gap size from a threshold (>60 µm) made the difference significant. Interaction analysis using two-way ANOVA also indicated the interaction between the emergence profile and space gap size.

The results emphasized that a straight profile with a smaller gap size should be considered to reduce the excess cement. However, due to the small sample size of the study, further analyses with different types of materials, angles of deformation, and gap sizes are required to reveal the exact relationship between excess cement and the design specifications.