Private practice, City Bell-La Plata, Buenos Aires, Argentina.
Director Graduate in Digital Dentistry, Catholic University of Córdoba, Córdoba, Argentina; Director Centro de Capacitación CAD3D, City Bell-La Plata, Buenos Aires, Argentina; Director Educational Center in Digital Dentistry, Valencia, Spain; Visiting Faculty, Graduate in Prosthodontics and Implants, Rey Juan Carlos University, Madrid, Spain; Private practice, City Bell-La Plata, Buenos Aires, Argentina.
J Prosthet Dent. 2022 Sep;128(3):513.e1-513.e11. doi: 10.1016/j.prosdent.2022.05.004. Epub 2022 Aug 5.
Interim dental restorations can be fabricated from additively manufactured ingots. However, the flexural strength and surface roughness of restorations fabricated by using this technique are unknown.
The purpose of this in vitro study was to assess the influence of the manufacturing method (milling, additive manufacturing, or a combination of subtractive and additive methods) and accelerating aging on the flexural strength and surface roughness of interim dental materials.
A bar design (25×2×2 mm) was used to fabricate the specimens by using 3 methods: milling (M group), additive manufacturing (AM group), and a combination of subtractive and additive methods (AM+M group). In the M group, an interim material (CopraTemp PMMA) was used to fabricate the milled (350i imes-icore) specimens. In the AM group, specimens were fabricated by using a printer (Form3B+) and an interim resin (Temporary CB) according to the manufacturer's protocol. In the AM+M group, specimens were milled from AM ingots (Temporary CB) and with the same milling machine as in the M group. Two subgroups were created based on the artificial aging (thermocycling): nonaged and aged (n=10). Flexural strength was calculated by using a universal testing machine, followed by determination of the Weibull distribution. Surface roughness was measured by using a digital microscope. The Shapiro-Wilk test revealed that the flexural strength and surface roughness (Ra) data were normally distributed (P>.05). Two-way ANOVA followed by post hoc multiple comparison Tukey tests were used to examine the data (α=.05). The Shapiro-Wilk test revealed that the surface roughness area data were not normally distributed (P<.05). Therefore, the Kruskal-Wallis followed by pairwise multiple comparisons tests were selected (α=.05).
Manufacturing methods (P<.001) and artificial aging (P=.043) were significant factors in the flexural strength measured. The M group had the highest flexural strength mean values (180 MPa), while the AM group showed the lowest flexural strength mean values (77 MPa). Additionally, nonaged specimens (128 MPa) had significantly higher flexural strength values than aged specimens (117 MPa). Manufacturing method (P<.001) was a significant factor in the surface roughness measured. The M group had the highest linear surface roughness mean values (0.86 μm), while the AM group showed the lowest linear surface roughness mean values (0.49 μm).
Manufacturing method and thermocycling influenced the flexural strength and surface roughness of the groups tested.
临时牙修复体可以由增材制造的铸锭制成。然而，使用这种技术制造的修复体的弯曲强度和表面粗糙度尚不清楚。
本体外研究的目的是评估制造方法（铣削、增材制造或减材和增材混合方法）和加速老化对临时牙科材料弯曲强度和表面粗糙度的影响。
使用 3 种方法（铣削、增材制造和减材与增材混合方法）制造试件：铣削（M 组）、增材制造（AM 组）和减材与增材混合方法（AM+M 组）。在 M 组中，使用一种临时材料（CopraTemp PMMA）制造铣削（350imes-icore）试件。在 AM 组中，根据制造商的协议，使用打印机（Form3B+）和一种临时树脂（Temporary CB）制造试件。在 AM+M 组中，使用增材制造铸锭（Temporary CB）并使用与 M 组相同的铣床进行铣削。根据人工老化（热循环）创建了 2 个亚组：未老化和老化（n=10）。使用万能试验机计算弯曲强度，然后确定威布尔分布。使用数字显微镜测量表面粗糙度。Shapiro-Wilk 检验表明弯曲强度和表面粗糙度（Ra）数据呈正态分布（P>.05）。采用双因素方差分析和事后多重比较 Tukey 检验进行数据分析（α=.05）。Shapiro-Wilk 检验表明表面粗糙度面积数据呈非正态分布（P<.05）。因此，选择了 Kruskal-Wallis 检验和两两比较检验（α=.05）。
制造方法（P<.001）和人工老化（P=.043）是弯曲强度测量的显著因素。M 组的弯曲强度平均值最高（180 MPa），而 AM 组的弯曲强度平均值最低（77 MPa）。此外，未老化试件（128 MPa）的弯曲强度值显著高于老化试件（117 MPa）。制造方法（P<.001）是测量表面粗糙度的显著因素。M 组的线性表面粗糙度平均值最高（0.86 μm），而 AM 组的线性表面粗糙度平均值最低（0.49 μm）。
制造方法和热循环影响了所测试组的弯曲强度和表面粗糙度。
