Abstract
There has been an increase in utilizing 3D printers in dental restorations. The purpose of the study is to compare mechanical properties of 3D-printed prostheses to those of self-cured and/or computer-aided design-computer-aided manufacturing (CAD-CAM) restorations. A metal master typodont was prepared for the mandibular left sextant with implant analogs embedded at the first premolar and first molar positions with a missing second premolar. Three-unit provisional fixed dental prosthesis (FDP) was designed utilizing the 3Shape tooth library and forty-five uniform specimens were fabricated with different materials: self-cured poly(methyl methacrylate) (PMMA) (N = 15), milled PMMA CAD-CAM blocks (N = 15) and 3D-printed resin (N = 15). All specimens were tested using an Instron machine at a crosshead speed of 0.5 mm/min by an axial load on the occlusal surface of the second premolar pontic site. Statistical analysis was completed with Shapiro-Wilk, ANOVA and Tukey post-hoc tests. Mean fracture force was 300.61 N, 294.64 N and 408.49 N for self-cured PMMA, milled PMMA and 3D-printed resin, respectively. Mean force at FDP fracture of 3D-printed resin was significantly greater than the mean fracture force of either self-cured (p = 0.016, 95% CI [17.86, 197.91]) or milled (p = 0.010, 95% CI [23.83, 203.88]) PMMA.
Highlights
Provisional restorations are essential for treatment, providing protection to prepared tooth structure, pulp and surrounding periodontal tissues [1,2,3,4,5]
computer-aided design-computer-aided manufacturing (CAD-CAM) of Poly(methyl methacrylate) (PMMA) provisional prostheses avoids heat of polymerization and shrinkage associated with self-cured PMMA
This study aims to investigate the impact of manufacture technique on the fracture strength of provisional resin 3-unit fixed dental prostheses (FDPs)
Summary
Provisional restorations are essential for treatment, providing protection to prepared tooth structure, pulp and surrounding periodontal tissues [1,2,3,4,5]. Poly(methyl methacrylate) (PMMA) is a popular material for provisional restorations due to high strength, color stability and ease of repair [11]. Chairside fabrication with self-cured PMMA results in an exothermic reaction which may irritate pulpal tissues and polymerization shrinkage which may cause distortion of the restoration [3]. CAD-CAM of PMMA provisional prostheses avoids heat of polymerization and shrinkage associated with self-cured PMMA. The advantages of provisional restorations via CAD-CAM process over conventional curing include increased durability [1,3,4,12,13], improved fit [3,4] and color stability [4]. Fabrication with milling has disadvantages: material waste, introduction of microcracks and limited reproduction of surface details depending on the size of the milling instrumentation [14]
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