Impact of simulated reduced alveolar bone support, increased tooth mobility, and distal post-supported, root-treated abutment tooth on load capability of all-ceramic zirconia-supported cantilever FDP.

Abstract

The aim of this in vitro study was an analysis of the impact of simulated reduced alveolar bone support and post-restored, endodontically treated distal abutment tooth on load capability of all-ceramic zirconia-based cantilever-fixed dental prosthesis (CFDP). The roots of human lower sound premolars (n = 80) were divided into five experimental groups to be restored with all-ceramic zirconia-supported three-unit CFDP regarding bone loss (BL) relative to the cement-enamel junction (CEJ): 2mm below CEJ = 0% BL (control group), group 25% distal BL, group 50% distal BL, group 50% mesial and distal BL, and group 50% distal BL and adhesive post-supported restoration. Specimens were exposed to simulated clinical function by thermo-mechanical loading (6.000 cycles 5°-55°; 1.2 × 106 cycles 0-50N) and subsequent linear loading until failure. Tooth mobility increased significantly for groups with simulated bone loss (p < 0.001). Four specimens failed during thermal cycling and mechanical loading (TCML). The maximum load capability ranged from 350 to 569N, and did not differ significantly between experimental groups (p = 0.095). Groups with simulated bone loss revealed more tooth fractures at distal abutment teeth, whereas technical failures were more frequent in the control group (p = 0.024). Differences of alveolar bone support and respectively increased tooth mobility between mesial and distal abutments did not influence load capability. A distal adhesively post-and-core-supported, root-treated abutment tooth did not increase risk of three-unit CFDP failure. CFDPs are a treatment option used with caution when reduced alveolar bone support, increased tooth mobility, and distal post-supported, root-treated abutment teeth are involved.