Doctoral student, Loma Linda University School of Dentistry, Loma Linda, Calif.
Distinguished Professor, Loma Linda University School of Dentistry, Loma Linda, Calif.
J Prosthet Dent. 2018 Jan;119(1):108-115. doi: 10.1016/j.prosdent.2017.02.009. Epub 2017 May 12.
Data comparing the denture tooth movement of computer-aided design and computer-aided manufacturing (CAD-CAM) and conventional denture processing techniques are lacking.
The purpose of this in vitro study was to compare the denture tooth movement of pack-and-press, fluid resin, injection, CAD-CAM-bonded, and CAD-CAM monolithic techniques for fabricating dentures to determine which process produces the most accurate and reproducible prosthesis.
A total of 50 dentures were evaluated, 10 for each of the 5 groups. A master denture was fabricated and milled from prepolymerized poly(methyl methacrylate). For the conventional processing techniques (pack-and-press, fluid resin, and injection) a polyvinyl siloxane putty mold of the master denture was made in which denture teeth were placed and molten wax injected. The cameo surface of each wax-festooned denture was laser scanned, resulting in a standard tessellation language (STL) format file. The CAD-CAM dentures included 2 subgroups: CAD-CAM-bonded teeth in which the denture teeth were bonded into the milled denture base and CAD-CAM monolithic teeth in which the denture teeth were milled as part of the denture base. After all specimens had been fabricated, they were hydrated for 24 hours, and the cameo surface laser scanned. The preprocessing and postprocessing scan files of each denture were superimposed using surface-matching software. Measurements were made at 64 locations, allowing evaluation of denture tooth movement in a buccal, lingual, mesial-distal, and occlusal direction. The use of median and interquartile range values was used to assess accuracy and reproducibility. Levene and Kruskal-Wallis analyses of variance were used to evaluate differences between processing techniques (α=.05).
The CAD-CAM monolithic technique was the most accurate, followed by fluid resin, CAD-CAM-bonded, pack-and-press, and injection. CAD-CAM monolithic technique was the most reproducible, followed by pack-and-press, CAD-CAM-bonded, injection, and fluid resin. Techniques involving compression during processing showed increased positive occlusal tooth movement compared with techniques not involving compression.
CAD-CAM monolithic dentures produced the best combination of accuracy and reproducibility of the tested techniques. The results from this study demonstrate that varying amounts of tooth movement can be expected depending on the processing technique. However, the clinical significance of these differences is unknown.
缺乏比较计算机辅助设计和计算机辅助制造（CAD-CAM）与传统义齿加工技术的义齿牙移动数据。
本体外研究的目的是比较包埋加压、流体树脂、注射、CAD-CAM 结合和 CAD-CAM 整体技术制造义齿的义齿牙移动，以确定哪种工艺产生最准确和可重复的义齿。
共评估了 50 个义齿，每个组 10 个。从预聚合聚甲基丙烯酸甲酯制成主义齿并进行铣削。对于传统加工技术（包埋加压、流体树脂和注射），主义齿的聚硅氧烷油灰模具被制作，其中放置义齿牙并用熔融蜡注入。每个蜡花饰义齿的乳突表面用激光扫描，生成标准三角形语言（STL）格式文件。CAD-CAM 义齿包括 2 个亚组：CAD-CAM 结合牙，其中义齿牙被结合到铣削的义齿基中，以及 CAD-CAM 整体牙，其中义齿牙作为义齿基的一部分被铣削。制造完所有样本后，将其水合 24 小时，然后用激光扫描乳突表面。使用表面匹配软件将每个义齿的预处理和后处理扫描文件叠加。在 64 个位置进行测量，允许评估颊、舌、近远中和咬合方向的义齿牙移动。中位数和四分位距值的使用用于评估加工技术之间的准确性和可重复性。使用 Levene 和 Kruskal-Wallis 方差分析评估加工技术之间的差异（α=0.05）。
CAD-CAM 整体技术是最准确的，其次是流体树脂、CAD-CAM 结合、包埋加压和注射。CAD-CAM 整体技术是最可重复的，其次是包埋加压、CAD-CAM 结合、注射和流体树脂。在加工过程中涉及压缩的技术显示出与不涉及压缩的技术相比，正向咬合牙移动增加。
CAD-CAM 整体义齿产生了测试技术中准确性和可重复性的最佳组合。本研究的结果表明，根据加工技术，可能会出现不同程度的牙齿移动。但是，这些差异的临床意义尚不清楚。
