Pera Francesco, Pesce Paolo, Bagnasco Francesco, Pancini Nicolò, Carossa Massimo, Baldelli Lorenzo, Annunziata Marco, Migliorati Marco, Baldi Domenico, Menini Maria
C.I.R. Dental School, Department of Surgical Sciences, University of Turin, 10126 Turin, Italy.
Department of Surgical Sciences (DISC), University of Genoa, 16132 Genoa, Italy.
Materials (Basel). 2023 Jan 15;16(2):833. doi: 10.3390/ma16020833.
The aim of the present study was to investigate the accuracy of a new digital impression system, comparing it to the plaster impression technique in the realization of full-arch implant-supported metal frameworks.
We took 11 scans (8 of the upper maxilla and 3 of the lower jaw) on a sample of nine patients previously rehabilitated with fixed full-arch screw-retained prostheses following the Columbus Bridge Protocol (CBP) with four to six implants (total: 51) since at least 4 months. Two impressions were taken for each dental arch: one analogic plaster impression using pick-up copings and an open tray technique and a second one using an intra-oral scanner. Two milled metal substructures were realised. The precision and passivity of the substructures were clinically analysed through the Sheffield test and endo-oral radiographs. Laboratory scans of the plaster casts obtained from an intra-oral scanner (IOS) and of the plaster casts obtained from traditional impression were compared with the intraoral scans following Hausdorff's method and an industrial digital method of optical detection to measure discrepancies. A Mann-Whitney test was performed in order to investigate average distances between surfaces after the superposition.
The Sheffield test demonstrated an excellent passivity of the frameworks obtained through both the digital and the analogic method. In 81.81% of cases (n = 9) both substructures were found to have a perfect fit with excellent passivity, while in 18.18% (n = 2) of cases the substructures were found to have a very slight discrepancy. From the radiographic examination, no gaps between the frameworks and the implant heads or multiunit abutments were observed, with 100% accuracy. By superimposing digital files of scans according to Hausdorff's method, a statistically significant discrepancy ( = 0.006) was found between the digital scans and the digital models obtained from plaster impressions. Three-dimensional optical detection found a mean discrepancy of 0.11 mm between the analogic cast and the cast derived from the digital impression.
The present study clinically demonstrates that milled implant-supported full-arch frameworks obtained through a digital scan and the herein described technique have an accuracy comparable to those obtained with traditional plaster impression.
本研究的目的是调查一种新型数字印模系统的准确性，并将其与在制作全牙弓种植体支持的金属框架时的石膏印模技术进行比较。
我们对9名患者的样本进行了11次扫描（上颌8次，下颌3次），这些患者此前按照哥伦布桥接协议（CBP），使用4至6颗种植体（共51颗）进行了固定全牙弓螺丝固位修复，时间至少为4个月。每个牙弓取两次印模：一次使用取模帽和开放式托盘技术取模拟石膏印模，另一次使用口腔内扫描仪取模。制作了两个铣削金属子结构。通过谢菲尔德测试和口腔内X光片对这些子结构的精度和被动性进行临床分析。将从口腔内扫描仪（IOS）获得的石膏模型的实验室扫描结果与从传统印模获得的石膏模型的扫描结果，按照豪斯多夫方法和一种工业数字光学检测方法进行比较，以测量差异。进行曼-惠特尼检验以研究叠加后表面之间的平均距离。
谢菲尔德测试表明，通过数字方法和模拟方法获得的框架均具有出色的被动性。在81.81%的病例（n = 9）中，两个子结构均被发现具有完美贴合且被动性极佳，而在18.18%（n = 2）的病例中，子结构被发现存在非常轻微的差异。从X光检查中，未观察到框架与种植体头部或多单位基台之间有间隙，准确率为100%。根据豪斯多夫方法叠加扫描的数字文件后，发现数字扫描与从石膏印模获得的数字模型之间存在统计学上的显著差异（ = 0.006）。三维光学检测发现模拟模型与数字印模衍生的模型之间的平均差异为0.11毫米。
本研究在临床上证明，通过数字扫描和本文所述技术获得的铣削种植体支持的全牙弓框架的准确性与传统石膏印模获得的框架相当。
