Alghazzawi Tariq F
Department of Substitutive Dental Sciences, Taibah University, Madinah 42353, Saudi Arabia.
Department of Mechanical and Materials Engineering, The University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Polymers (Basel). 2023 Nov 3;15(21):4312. doi: 10.3390/polym15214312.
Polymeric materials show great promise for use in a variety of dental applications. Manufacturers generally provide flexural strength information based on standardized (ISO and ASTM) specimen dimensions and loading conditions. It is not clear, however, if flexural strength data are predictive of the clinical performance of dental crowns. The objectives of this study were, therefore, to determine whether flexural strengths, as measured via three-point bending (3PB), would be predictive of failure loads assessed via crunch-the-crown (CTC) tests. Three brands of polymers (Trilor, Juvora, and Pekkton) were fabricated into rectangular bars and fully contoured crowns (10 specimens of each polymer brand, 30 specimens of each shape). Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and burn off tests were used to characterize/confirm the materials. Bars were tested blindly in 3PB to determine flexural strength, and crowns were CTC-tested to determine failure load after luting to resin abutments. The statistical significance of the test results was evaluated via one-way ANOVA (α = 0.05) and Pearson's correlation coefficient, while regression analysis was used to test for a correlation between 3PB and CTC results. The fracture mechanisms and failure surface characteristics were characterized using scanning electron microscopy (SEM). There were significant differences ( < 0.05) in the mean crown failure loads (Trilor (7033 N) > Juvora (5217 N) > Pekkton (3023 N)) and mean flexural strengths of the bars (Trilor (468 MPa) > Juvora (197 MPa) = Pekkton (192 MPa)). The mode of crown fracture was different between the materials and included deformation (Juvora), ductile-to-brittle fracture (Pekkton), and a combination of cracks and deformation (Trilor). Flexural strengths did not correlate with the corresponding crown failure loads for any of the materials tested. These results suggest that dental practitioners should not rely on the flexural strengths reported from three-point bending tests, as advertised by the manufacturer, to predict the performance of polymeric crowns.
聚合材料在多种牙科应用中显示出巨大的应用前景。制造商通常会根据标准化（ISO和ASTM）的试样尺寸和加载条件提供弯曲强度信息。然而，尚不清楚弯曲强度数据是否能预测牙冠的临床性能。因此，本研究的目的是确定通过三点弯曲（3PB）测量的弯曲强度是否能预测通过咬冠（CTC）试验评估的破坏载荷。将三种品牌的聚合物（Trilor、Juvora和Pekkton）制成矩形棒和全轮廓牙冠（每个聚合物品牌10个试样，每种形状30个试样）。采用差示扫描量热法（DSC）、傅里叶变换红外光谱法（FTIR）和燃烧试验对材料进行表征/确认。对棒材进行盲法3PB测试以确定弯曲强度，对牙冠进行CTC测试以确定粘结到树脂基台后的破坏载荷。通过单因素方差分析（α = 0.05）和Pearson相关系数评估测试结果的统计学意义，同时使用回归分析来测试3PB和CTC结果之间的相关性。使用扫描电子显微镜（SEM）对断裂机制和破坏表面特征进行表征。牙冠平均破坏载荷（Trilor（7033 N）> Juvora（5217 N）> Pekkton（3023 N））和棒材平均弯曲强度（Trilor（468 MPa）> Juvora（197 MPa） = Pekkton（192 MPa））存在显著差异（< 0.05）。不同材料之间牙冠断裂模式不同，包括变形（Juvora）、韧性到脆性断裂（Pekkton）以及裂纹和变形的组合（Trilor）。对于所测试的任何材料，弯曲强度均与相应的牙冠破坏载荷无关。这些结果表明，牙科医生不应依赖制造商宣传的三点弯曲试验报告的弯曲强度来预测聚合物牙冠的性能。
