Graduate student, Graduate Prosthodontics, Department of Prosthodontics, College of Dentistry, University of Tennessee Health Science Center, Memphis, Tenn.
Professor, Department of Prosthodontics, College of Dentistry, University of Tennessee Health Science Center, Memphis, Tenn.
J Prosthet Dent. 2022 Feb;127(2):275.e1-275.e7. doi: 10.1016/j.prosdent.2021.11.005. Epub 2021 Dec 10.
New techniques and materials for the laboratory fabrication of interim fixed dental prostheses have gained in popularity, yet how their failure strengths compare with conventional chairside materials is unclear.
The purpose of this in vitro study was to compare the strength of computer-aided design and computer-aided manufacturing (CAD-CAM) milled polymethylmethacrylate (PMMA) or 3-dimensionally (3D) printed bis-acryl interim fixed dental prostheses with a traditional chairside-dispensed autopolymerizing bis-acryl prosthesis while taking into account the effect of loading rate and storage time.
A dentiform mandibular second premolar and second molar with a first molar pontic were prepared and scanned. Three groups of 3-unit interim fixed dental prostheses were fabricated: milled PMMA, 3D-printed bis-acryl, and chairside-dispensed autopolymerizing bis-acryl. The interim prostheses were evaluated for fit with a silicone disclosing material and cemented onto 3D-printed resin dies. The specimens were stored in 100% humidity at 37 °C. After 1 or 30 days of storage, the cemented interim prostheses were loaded to failure in a universal testing machine at 1 or 10 mm/min (n=15/group). Failure loads were analyzed by 3-way analysis of variance and multiple comparisons (α=.05).
Mean ±standard deviation failure loads ranged from 363 ±93 N (3D-printed bis-acryl, 30 days, 1 mm/min) to 729 ±113 N (milled PMMA, 24 hours, 1 mm/min). Loading rate did not significantly affect failure load of the interim prostheses (P=.306). After 30 days of storage in 100% humidity, the failure load of milled PMMA and 3D-printed bis-acryl interim prostheses decreased significantly, but the chairside autopolymerizing bis-acryl prostheses were not affected. After 30 days of storage, the failure loads of milled PMMA and chairside autopolymerizing bis-acryl were not significantly different.
Regardless of loading rate, interim fixed dental prostheses from milled PMMA had the highest initial strength 1 day after storage. Thirty days of exposure to humidity, however, reduced the strength of the CAD-CAM-manufactured interim prostheses, whereas the traditional chairside prostheses retained their strength.
用于实验室制作临时固定义齿的新技术和材料越来越受欢迎，但它们的失效强度与传统的椅旁材料相比如何尚不清楚。
本体外研究的目的是比较计算机辅助设计和计算机辅助制造（CAD-CAM）铣削聚甲基丙烯酸甲酯（PMMA）或 3 维（3D）打印双丙烯酸临时固定义齿与传统椅旁分配自聚合双丙烯酸义齿的强度，同时考虑加载速度和储存时间的影响。
制备并扫描具有第一磨牙桥的下颌第二前磨牙和第二磨牙。制作了三组 3 单位临时固定义齿：铣削 PMMA、3D 打印双丙烯酸和椅旁分配自聚合双丙烯酸。使用硅酮显影材料评估临时义齿的适合性，并将其粘接到 3D 打印树脂模具上。将标本在 37°C 的 100%湿度下储存。储存 1 或 30 天后，将粘合的临时义齿在万能试验机上以 1 或 10mm/min 的速度加载至失效（每组 n=15）。通过 3 因素方差分析和多重比较（α=.05）分析失效负载。
平均±标准偏差失效负载范围为 363±93N（3D 打印双丙烯酸，30 天，1mm/min）至 729±113N（铣削 PMMA，24 小时，1mm/min）。加载速度对临时义齿的失效负载没有显著影响（P=.306）。在 100%湿度下储存 30 天后，铣削 PMMA 和 3D 打印双丙烯酸临时义齿的失效负载显著降低，但椅旁自聚合双丙烯酸义齿不受影响。储存 30 天后，铣削 PMMA 和椅旁自聚合双丙烯酸的失效负载无显著差异。
无论加载速度如何，储存 1 天后，铣削 PMMA 的临时固定义齿具有最高的初始强度。然而，30 天暴露于湿度会降低 CAD-CAM 制造的临时义齿的强度，而传统的椅旁义齿则保持其强度。
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