Fracture load of milled polymeric fixed dental prostheses as a function of connector cross-sectional areas

Abstract

Polymeric computer-aided design/computer-aided manufacturing (CAD/CAM) blocks exhibit various advantages in contrast to conventionally processed resin restorations. However, the influence of connector dimensions on resin fixed dental prostheses (FDPs) has not yet been investigated. This study evaluated the impact of connector cross-sectional area (CSA) on the fracture load of 3-unit CAD/CAM FDPs and compared this with conventionally fabricated ones. Anatomically shaped 3-unit FDPs with the CSAs of 6, 9, 12, and 16 mm(2) (N=240, n=15 per material and per CSA) were fabricated from the following CAD/CAM materials: artBloc Temp (AT), TelioCAD (TC), CAD-Temp (CT), and one conventional resin material, CronMix K (CMK) as the control group. The fracture load was tested and the data were analyzed with 2-way ANOVA, 1-way ANOVA, the Scheffé post hoc test, and Weibull statistics (α=05). CMK showed the significant lowest values for all CSAs followed by CT, except for the 12 mm(2) connector (P<.001). The CAD/CAM FDPs exhibited a significant increase in fracture load with the increase of CSA (P<.001). Conventionally fabricated FDPs presented an increase of values up to the CSA of 12 mm(2). For TC, the shape increased with a larger CSA. The other materials exhibited no tendencies in this regard. Among the 12 mm(2) groups, AT exhibited the highest shape value (19.1), and among the 16 mm(2) groups, TC showed the highest shape value (17.0). The CMK FDPs with a CSA of 16 mm(2) showed almost half as high a shape parameter (6.4) than the other three CSAs. CAD/CAM resin FDPs revealed significantly higher fracture load values than conventionally fabricated FDPs and showed a significant increase in fracture load with the increase of the CSA.