Precision and trueness of dental models manufactured with different 3-dimensional printing techniques.

INTRODUCTION: In this study, we assessed the precision and trueness of dental models printed with 3-dimensional (3D) printers via different printing techniques. METHODS: Digital reference models were printed 5 times using stereolithography apparatus (SLA), digital light processing (DLP), fused filament fabrication (FFF), and the PolyJet technique. The 3D printed models were scanned and evaluated for tooth, arch, and occlusion measurements. Precision and trueness were analyzed with root mean squares (RMS) for the differences in each measurement. Differences in measurement variables among the 3D printing techniques were analyzed by 1-way analysis of variance (α = 0.05). RESULTS: Except in trueness of occlusion measurements, there were significant differences in all measurements among the 4 techniques (P <0.001). For overall tooth measurements, the DLP (76 ± 14 µm) and PolyJet (68 ± 9 µm) techniques exhibited significantly different mean RMS values of precision than the SLA (88 ± 14 µm) and FFF (99 ± 14 µm) techniques (P <0.05). For overall arch measurements, the SLA (176 ± 73 µm) had significantly different RMS values than the DLP (74 ± 34 µm), FFF (89 ± 34 µm), and PolyJet (69 ± 18 µm) techniques (P <0.05). For overall occlusion measurements, the FFF (170 ± 55 µm) exhibited significantly different RMS values than the SLA (94 ± 33 µm), DLP (120 ± 28 µm), and PolyJet (96 ± 33 µm) techniques (P <0.05). There were significant differences in mean RMS values of trueness of overall tooth measurements among all 4 techniques: SLA (107 ± 11 µm), DLP (143 ± 8 µm), FFF (188 ± 14 µm), and PolyJet (78 ± 9 µm) (P <0.05). For overall arch measurements, the SLA (141 ± 35 µm) and PolyJet (86 ± 17 µm) techniques exhibited significantly different mean RMS values of trueness than DLP (469 ± 49 µm) and FFF (409 ± 36 µm) (P <0.05). CONCLUSIONS: The 3D printing techniques showed significant differences in precision of all measurements and in trueness of tooth and arch measurements. The PolyJet and DLP techniques were more precise than the FFF and SLA techniques, with the PolyJet technique having the highest accuracy.

Failure of setting of mineral trioxide aggregate in the presence of fetal bovine serum and its prevention.

INTRODUCTION: The purpose of this study was to examine the effect of fetal bovine serum (FBS) on the setting of 2 white mineral trioxide aggregates (MTAs) and to determine if calcium chloride (CaCl(2)) alters the setting behavior of both MTAs under this condition. METHODS: Two types of MTA cements (ProRoot MTA [Dentsply Tulsa Dental, Tulsa, OK] and MTA-Angelus [Angelus Dental Solutions, Londrina, Brazil]) were mixed with either distilled water (DW) or 10% CaCl(2) solution. Mixed MTA was placed in a polyethylene mold, and each mold was then placed in saline or FBS-soaked Oasis. After storing for 4 days, the MTA samples were removed from the molds, and the microhardness was independently measured at 3 different levels: 0.5 mm, 2 mm, and 4 mm away from the bottom in contact with the immersion solution. RESULTS: None of the samples mixed with DW and exposed to FBS for 4 days had set at the 0.5-mm and 2-mm levels. CaCl(2) was effective in reducing (the 0.5-mm level) or eliminating (the 2- and 4-mm levels) the adverse effect of FBS. The groups with short-term exposure to FBS had the same surface microhardness as the groups stored in saline-soaked Oasis. CONCLUSIONS: MTA did not set when the mixed MTA was exposed to FBS for 4 days. In these cases, 10% CaCl(2) helped the setting of MTA, and the effect was more pronounced in ProRoot MTA than in MTA-Angelus. In contrast, short-term exposure to FBS had minimal or no detrimental effects on the setting behaviors of both MTAs.