U.S. Army Advanced Education Program in Prosthodontics, Fort Gordon, GA.
Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA.
J Prosthodont. 2019 Apr;28(4):428-435. doi: 10.1111/jopr.12604. Epub 2017 Nov 14.
To compare the shrinkage of denture bases fabricated by three methods: CAD/CAM, compression molding, and injection molding. The effect of arch form and palate depth was also tested.
Nine titanium casts, representing combinations of tapered, ovoid, and square arch forms and shallow, medium, and deep palate depths, were fabricated using electron beam melting (EBM) technology. For each base fabrication method, three poly(vinyl siloxane) impressions were made from each cast, 27 dentures for each method. Compression-molded dentures were fabricated using Lucitone 199 poly methyl methacrylate (PMMA), and injection molded dentures with Ivobase's Hybrid Pink PMMA. For CAD/CAM, denture bases were designed and milled by Avadent using their Light PMMA. To quantify the space between the denture and the master cast, silicone duplicating material was placed in the intaglio of the dentures, the titanium master cast was seated under pressure, and the silicone was then trimmed and recovered. Three silicone measurements per denture were recorded, for a total of 243 measurements. Each silicone measurement was weighed and adjusted to the surface area of the respective arch, giving an average and standard deviation for each denture.
Comparison of manufacturing methods showed a statistically significant difference (p = 0.0001). Using a ratio of the means, compression molding had on average 41% to 47% more space than injection molding and CAD/CAM. Comparison of arch/palate forms showed a statistically significant difference (p = 0.023), with shallow palate forms having more space with compression molding. The ovoid shallow form showed CAD/CAM and compression molding had more space than injection molding.
Overall, injection molding and CAD/CAM fabrication methods produced equally well-fitting dentures, with both having a better fit than compression molding. Shallow palates appear to be more affected by shrinkage than medium or deep palates. Shallow ovoid arch forms appear to benefit from the use of injection molding compared to CAD/CAM and compression molding.
比较三种义齿基托制造方法（CAD/CAM、压缩成型和注塑成型）的收缩情况。还测试了拱架形状和 palate depth 的影响。
使用电子束熔化 (EBM) 技术制作了 9 个钛铸件，代表锥形、卵形和方形拱架形状以及浅、中和深 palate depth 的组合。对于每种基底制造方法，从每个铸件中制作了三个聚硅氧烷 (polyvinyl siloxane) 印模，每种方法有 27 个义齿。压缩成型的义齿使用 Lucitone 199 聚甲基丙烯酸甲酯 (PMMA) 制造，注塑成型的义齿使用 Ivobase 的 Hybrid Pink PMMA 制造。对于 CAD/CAM，义齿基托由 Avadent 使用他们的 Light PMMA 设计和铣削。为了量化义齿和主铸模之间的空间，将硅橡胶复制材料放置在义齿的凹处，在压力下将钛主铸模放置到位，然后修剪和恢复硅橡胶。每个义齿记录三个硅橡胶测量值，总共 243 个测量值。每个硅橡胶测量值均称重并调整到各自拱架的表面积，得出每个义齿的平均值和标准偏差。
制造方法的比较显示出统计学上的显著差异 (p = 0.0001)。使用平均值的比率，压缩成型的平均空间比注塑成型和 CAD/CAM 多 41%至 47%。拱架/牙弓形状的比较显示出统计学上的显著差异 (p = 0.023)，浅牙弓形状的压缩成型的空间更大。浅卵形的形状显示出 CAD/CAM 和压缩成型的空间比注塑成型的大。
总体而言，注塑成型和 CAD/CAM 制造方法制作的义齿同样贴合，两者的贴合度均优于压缩成型。浅牙弓似乎比中或深牙弓更容易受到收缩的影响。与 CAD/CAM 和压缩成型相比，浅卵形牙弓形状似乎受益于注塑成型的使用。
