Carlos A Jurado, Francisco X Azpiazu-Flores, Mark A Antal, Silvia Rojas-Rueda, Damian J Lee
The fracture load of 3-unit FDPs fabricated from milled and 3D printed contemporary CAD-CAM resin materials for interim tooth-supported restorations differed significantly. Among the materials tested, the 3D printed resin presented a fracture load that was either comparable to or exceeded that of the milled polymethyl methacrylate (PMMA)-based restorative polymers evaluated.
STATEMENT OF PROBLEM: Although several studies have evaluated the mechanical properties of contemporary computer-aided design and computer-aided manufacturing (CAD-CAM) polymers for interim tooth-supported restorations, research describing mechanical testing under clinically representative conditions is limited.
PURPOSE: The purpose of this in vitro study was to compare the fracture load of interim 3-unit fixed dental prostheses (FDPs) fabricated from 6 different materials.
MATERIAL AND METHODS: A 3-unit interim FDP including the maxillary right canine and right first molar as retainers and a premolar as a pontic was digitally designed. The tooth preparations consisted of 1.5 mm of occlusal reduction, 1.0 mm of axial reduction, and a 1.0-mm chamfer finish line. The prostheses were fabricated using 6 different materials for interim restorations (n=7 per group): BeautyZir Multilayer PMMA, Dentsply Multilayer PMMA, Harvest Esthetic DCL, Structure CAD, and VITA CAD Temp; and a 3-dimensionally (3D) printed photopolymer (Sculpture 2.0). The restorations were positioned on custom-made aluminum dies, and their fracture load (N) was evaluated in a universal testing machine. The data were analyzed using the Welch-corrected 1-way ANOVA and Bonferroni-corrected Tukey honestly significant difference (HSD) test (α=.05).
RESULTS: The Sculpture 2.0 group exhibited the highest mean ±standard deviation fracture load of all groups (1077.0 ±48.88 N), followed closely by Dentsply Multilayer PMMA (1046.8 ±45.93 N) and Harvest Esthetic DCL (948.7 ±35.18 N). BeautyZir Multilayer PMMA (709.8 ±64.81 N) and Structure CAD (615.0 ±99.93 N) presented moderate fracture load. VITA CAD presented the lowest strength and the highest variability of all groups (307.0 ±142.15 N).
CONCLUSIONS: The fracture load of 3-unit FDPs fabricated from milled and 3D printed contemporary CAD-CAM resin materials for interim tooth-supported restorations differed significantly. Among the materials tested, the 3D printed resin presented a fracture load that was either comparable to or exceeded that of the milled polymethyl methacrylate (PMMA)-based restorative polymers evaluated.