Dimensions of Posterior Implant Restorations Related to Intra-Coronal Cantilever and Occlusal Forces: An In Vitro Study.

Objective: The aim of the present study was to investigate the relation of the implant position to the implant crown and analyze the location and magnitude of bite force.

Materials and methods: The dimensions of 49 posterior implant-supported restorations were recorded in terms of: 1. implant diameter, 2. crown length, 3. crown width, 4. crown height, 5. occlusal surface of the restoration. The crown/implant height was measured and the distance between the implant center and the restoration center revealed the size of intra-coronal cantilevers. The occlusal force analysis determined the point and magnitude of loading. Correlation coefficient r was used for the statistical process and statistical control was carried out with the aid of t-test with minimum level of significance p < 0.05.

Results: - The mean crown-to-implant ratio was 0.9 and in short implants (< 10mm) the ratio was 1.28. - Intra-coronal cantilever extensions ranged from 2.1 mm to 6.35 mm depending on crown size. - Occlusal loading was identified in cantilever areas of the crown.

Conclusions: - Implant center deviates from crown center in 71%-82% of the cases depending on site location. - Implants with non-ideal position may support a functionally occluding crown.

Clinical significance: Intra-coronal cantilevers are a critical factor to avoid clinical complications and should be taken under consideration both in the planning and fabrication phase of implant restorations.