Fracture Strength of Six-Unit Anterior Fixed Provisional Restorations Fabricated Using Various Dental CAD/CAM Systems

Purpose: This study compares the fracture strengths of long-span fixed provisional restorations fabricated via digital additive and subtractive methods to those fabricated via conventional heat-processing techniques. Materials and Methods: A six-unit anterior partial restoration was designed as an anatomical and morphologic structure using a dental CAD/CAM system. The provisional restorations (N = 40) of four different fabrication methods (n = 10 per group) were used for the failure loading test: stereolithography apparatus (SLA), liquid crystal display (LCD), milling (MIL), and heat-processed temporary (HPT). The specimens were subjected to a maximum load-to-fracture test using a universal testing machine, and the representative fracture patterns were observed. Statistical analysis was performed using Shapiro-Wilk, Kruskal-Wallis, Mann-Whitney U, and Bonferroni post hoc tests (P <.05). Results: The four groups showed significant differences in fracture strength according to the materials and manufacturing methods used (P <.001, except between SLA and HPT groups). The fracture strengths of MIL and LCD digitally fabricated groups were significantly higher than that of the HPT group (P <.001). Conclusions: The subtractive method is ideal for fabricating long-span fixed provisional restorations for long-term use. Additionally, LCD additive manufacturing technology could soon be a good alternative for restorations.