Load-bearing capacity of CAD/CAM milled polymeric three-unit fixed dental prostheses: Effect of aging regimens

Abstract

This study tested the fracture load of milled and conventionally fabricated polymeric and glass-ceramic three-unit fixed dental prostheses (FDPs) after aging. FDPs were fabricated (N = 1,050) from four computer-aided design and computer-aided manufacturing (CAD/CAM) resins: (1) AT (artBlock Temp); (2) TC (Telio CAD); (3) ZP (ZENO PMMA); (4) CT (CAD-Temp); two conventionally fabricated resins, (5) IES (integral esthetic press), (6) CMK (CronMix K), and a glass-ceramic (control) (7) PG (IMAGINE PressX). Specimens of each group were tested immediately after fabrication (n = 15 per material). Seventy-five FDPs per material type were stored in artificial saliva (37°C) and 15 of them were randomly selected after aging (1, 7, 28, 90, and 180days) for fracture load measurement. The remaining specimens (n = 60 per material) were subjected to chewing simulation (×120.000-1.200.000, 49N, 5°C/50°C). The data were analyzed using two-way and one-way ANOVA followed by Scheffé test. The interactions between FDP materials and aging time in both storage media showed a significant impact on the results (p < 0.001). Among saliva storage groups, TC and ZP showed the highest, and PG the lowest fracture load (p < 0.05). AT and CT were not affected from chewing simulation. TC, ZP, and AT presented the highest in ascending order (p < 0.05), PG and CMK showed the lowest fracture load after chewing simulation (p < 0.001). Aging did not influence the fracture load of FDPs made of CAD/CAM resins. FDPs made of glass-ceramic showed significantly lower fracture load than those of all resin FDPs. Considering fracture load measurements, CAD/CAM resins tested could be alternative materials to glass-ceramic for FDP construction.