Otani Takafumi, Raigrodski Ariel J, Mancl Lloyd, Kanuma Ikuru, Rosen Jacob
Graduate student, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
J Prosthet Dent. 2015 Aug;114(2):229-35. doi: 10.1016/j.prosdent.2015.02.021. Epub 2015 May 5.
Controlling tooth reduction for porcelain laminate veneers (PLVs) in fractions of millimeters is challenging.
The purpose of this study was to assess an automated robotic tooth preparation system for PLVs for accuracy and precision compared with conventional freehand tooth preparation.
Twenty maxillary central incisor tooth models were divided into 2 groups. Ten were assigned to a veneer preparation with a robotic arm according to preoperative preparation design-specific guidelines (experimental group). Ten were assigned to conventional tooth preparation by a clinician (control group). Initially, all tooth models were scanned with a 3- dimensional (3D) laser scanner, and a tooth preparation for PLVs was designed on a 3D image. Each tooth model was attached to a typodont. For the experimental group, an electric high-speed handpiece with a 0.9-mm-diameter round diamond rotary cutting instrument was mounted on the robotic arm. The teeth were prepared automatically according to the designed image. For the control group, several diamond rotary cutting instruments were used to prepare the tooth models according to preoperative preparation design guidelines. All prepared tooth models were scanned. The preoperative preparation design image and scanned postoperative preparation images were superimposed. The dimensional difference between those 2 images was measured on the facial aspect, finish line, and incisal edge. Differences between the experimental and the control groups from the 3D design image were computed. Accuracy and precision were compared for all sites and separately for each tooth surface (facial, finish line, incisal). Statistical analyses were conducted with a permutation test for accuracy and with a modified robust Brown-Forsythe Levene-type test for precision (α=.05).
For accuracy for all sites, the mean absolute deviation was 0.112 mm in the control group and 0.133 mm in the experimental group. No significant difference was found between the 2 (P=.15). For precision of all sites, the standard deviation was 0.141 mm in the control group and 0.185 mm in the experimental group. The standard deviation in the control group was significantly lower (P=.030). In terms of accuracy for the finish line, the control group was significantly less accurate (P=.038). For precision, the standard deviation in the control group was significantly higher at the finish line (P=.034).
For the data from all sites, the experimental procedure was able to prepare the tooth model as accurately as the control, and the control procedure was able to prepare the tooth model with better precision. The experimental group showed better accuracy and precision at the finish line.
将瓷贴面（PLV）的牙齿磨除量控制在毫米级以下具有挑战性。
本研究的目的是评估一种用于PLV的自动机器人牙齿预备系统与传统徒手牙齿预备相比的准确性和精确性。
20个上颌中切牙模型分为2组。10个根据术前预备设计的特定指南由机器人手臂进行贴面预备（实验组）。10个由临床医生进行传统牙齿预备（对照组）。最初，所有牙齿模型用三维（3D）激光扫描仪扫描，并在3D图像上设计PLV的牙齿预备。每个牙齿模型固定在一个牙列模型上。对于实验组，将一个配备直径0.9毫米圆形金刚石旋转切割器械的电动高速手机安装在机器人手臂上。牙齿根据设计图像自动预备。对于对照组，使用几种金刚石旋转切割器械根据术前预备设计指南预备牙齿模型。所有预备后的牙齿模型进行扫描。将术前预备设计图像和扫描后的术后预备图像叠加。在唇面、肩台和切缘测量这两个图像之间的尺寸差异。计算实验组和对照组与3D设计图像之间的差异。比较所有部位以及每个牙齿表面（唇面、肩台、切缘）的准确性和精确性。采用置换检验分析准确性，采用改良稳健的Brown-Forsythe Levene型检验分析精确性（α = 0.05）。
对于所有部位的准确性，对照组的平均绝对偏差为0.112毫米，实验组为0.133毫米。两组之间未发现显著差异（P = 0.15）。对于所有部位的精确性，对照组的标准差为0.141毫米，实验组为0.185毫米。对照组的标准差显著更低（P = 0.030）。在肩台的准确性方面，对照组明显更不准确（P = 0.038）。对于精确性，对照组在肩台处的标准差显著更高（P = 0.034）。
对于所有部位的数据，实验组的操作能够与对照组一样准确地预备牙齿模型，而对照组的操作能够更精确地预备牙齿模型。实验组在肩台处显示出更好的准确性和精确性。
