Associate Professor, Division of Restorative Science and Prosthodontics, College of Dentistry, The Ohio State University, Columbus, Ohio.
Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Mustafa Kemal University, Hatay, Turkey.
J Prosthet Dent. 2018 Jul;120(1):65-70. doi: 10.1016/j.prosdent.2017.11.021. Epub 2018 Feb 21.
Computer-aided design and computer-aided manufacturing (CAD-CAM) high-density polymers (HDPs) have recently been marketed for the fabrication of long-term interim implant-supported fixed prostheses. However, information regarding the precision of fit of CAD-CAM HDP implant-supported complete-arch screw-retained prostheses is scarce.
The purpose of this in vitro study was to evaluate the marginal discrepancy of CAD-CAM HDP complete-arch implant-supported screw-retained fixed prosthesis frameworks and compare them with conventional titanium (Ti) and zirconia (Zir) frameworks.
A screw-retained complete-arch acrylic resin prototype with multiunit abutments was fabricated on a typodont model with 2 straight implants in the anterior region and 2 implants with a 30-degree distal tilt in the posterior region. A 3-dimensional (3D) laboratory laser scanner was used to digitize the typodont model with scan bodies and the resin prototype to generate a virtual 3D CAD framework. A CAM milling unit was used to fabricate 5 frameworks from HDP, Ti, and Zir blocks. The 1-screw test was performed by tightening the prosthetic screw in the maxillary left first molar abutment (terminal location) when the frameworks were on the typodont model, and the marginal discrepancy of frameworks was evaluated using an industrial computed tomographic scanner and a 3D volumetric software. The 3D marginal discrepancy at the abutment-framework interface of the maxillary left canine (L1), right canine (L2), and right first molar (L3) sites was measured. The mean values for 3D marginal discrepancy were calculated for each location in a group with 95% confidence limits. The results were analyzed by repeated-measures 2-way ANOVA using the restricted maximum likelihood estimation and the Satterthwaite degrees of freedom methods, which do not require normality and homoscedasticity in the data. The between-subjects factor was material, the within-subjects factor was location, and the interaction was included in the model. Tukey tests were applied to resolve any statistically significant source of variation (overall α=.05).
The 3D marginal discrepancy measurement was possible only for L2 and L3 because the L1 values were too small to detect. The mean discrepancy values at L2 were 60 μm for HDP, 74 μm for Ti, and 84 μm for Zir. At the L3 location, the mean discrepancy values were 55 μm for HDP, 102 μm for Ti, and 94 μm for Zir. The ANOVA did not find a statistically significant overall effect for implant location (P=.072) or a statistically significant interaction of location and material (P=.078), but it did find a statistically significant overall effect of material (P=.019). Statistical differences were found overall between HDP and the other 2 materials (P≤.037).
When the tested materials were used with the CAD-CAM system, the 3D marginal discrepancy of CAD-CAM HDP frameworks was smaller than that of titanium or zirconia frameworks.
计算机辅助设计和计算机辅助制造（CAD-CAM）高密度聚合物（HDPs）最近已投放市场，用于制造长期临时植入物支持的固定修复体。然而，关于 CAD-CAM HDP 植入物支持的全弓螺丝固定修复体的适合精度的信息很少。
本体外研究的目的是评估 CAD-CAM HDP 全弓植入物支持的螺丝固定修复体框架的边缘不匹配，并将其与传统钛（Ti）和氧化锆（Zir）框架进行比较。
在前部区域的 2 个直植入物和后部区域的 2 个具有 30 度远倾的植入物上，在典型模型上制造了带有多单位基台的螺丝固定全弓丙烯酸树脂原型。使用三维（3D）实验室激光扫描仪对典型模型和树脂原型进行数字化，以生成虚拟的 3D CAD 框架。使用 CAM 铣削单元从 HDP、Ti 和 Zir 块制造 5 个框架。当框架位于典型模型上时，通过拧紧上颌左侧第一磨牙基台（末端位置）中的修复体螺丝来进行单螺丝测试，并使用工业计算机断层扫描扫描仪和 3D 体积软件评估框架的边缘不匹配。测量上颌左侧犬齿（L1）、右侧犬齿（L2）和右侧第一磨牙（L3）位点的基台-框架界面的 3D 边缘不匹配。在每个位置计算 3D 边缘不匹配的平均值，并在具有 95%置信限的组内进行计算。使用限制最大似然估计和 Satterthwaite 自由度方法的重复测量 2 方式方差分析来分析结果，该方法不需要数据的正态性和同方差性。受试者因素为材料，受试者内因素为位置，模型中包含交互作用。应用 Tukey 检验来解决任何具有统计学意义的变异源（总α=.05）。
仅对于 L2 和 L3 可以进行 3D 边缘不匹配测量，因为 L1 值太小而无法检测。L2 处的平均差异值为 HDP 为 60μm，Ti 为 74μm，Zir 为 84μm。在 L3 位置，平均差异值为 HDP 为 55μm，Ti 为 102μm，Zir 为 94μm。方差分析未发现植入物位置的总体统计学显著影响（P=.072）或位置和材料的统计学显著交互作用（P=.078），但发现材料的总体统计学显著影响（P=.019）。总体上，在 HDP 和其他 2 种材料之间发现了统计学差异（P≤.037）。
当使用 CAD-CAM 系统测试这些材料时，CAD-CAM HDP 框架的 3D 边缘不匹配小于钛或氧化锆框架。
