Cesur M G, Omurlu I K, Ozer T
Department of Orthodontics, Faculty of Dentistry, Adnan Menderes University, Aydin, Turkey.
Department of Biostatistics, Faculty of Medicine, Adnan Menderes University, Aydin, Turkey.
Niger J Clin Pract. 2017 Sep;20(9):1175-1181. doi: 10.4103/1119-3077.197012.
The aim of this study was to evaluate the accuracy of digital models produced with the three-dimensional dental scanner, and to test the dimensional stability of alginate impressions for durations of immediately (T0), 1 day (T1), and 2 days (T2).
A total of sixty impressions were taken from a master model with an alginate, and were poured into plaster models in three different storage periods. Twenty impressions were directly scanned (negative digital models), after which plaster models were poured and scanned (positive digital models) immediately. The remaining 40 impressions were poured after 1 and 2 days. In total, 9 points and 11 linear measurements were used to analyze the plaster models, and negative and positive digital models. Time-dependent deformation of the alginate impressions and the accuracy of the conventional plaster models and digital models were evaluated separately.
Plaster models, negative and positive digital models showed significant differences in nearly all measurements at T (0), T (1), and T (2) times (P < 0.01, P < 0.05, and P < 0.001). Arch perimeter measurements did not differ at T (0) and T (1) times (P > 0.05), but they demonstrated statistically significant differences at T (2) time (P < 0.05) between the models.
This study showed that measurements on negative digital models offer a high degree of validity when compared to measurements on positive digital models and plaster models; differences between the techniques are clinically acceptable. Direct scanning of the impressions is practicable method for orthodontists.
本研究旨在评估三维牙科扫描仪生成的数字模型的准确性，并测试藻酸盐印模在即刻（T0）、1天（T1）和2天（T2）时间段内的尺寸稳定性。
用藻酸盐从一个主模型上制取总共60个印模，并在三个不同的储存时间段内灌注成石膏模型。20个印模直接扫描（负性数字模型），之后立即灌注石膏模型并扫描（正性数字模型）。其余40个印模在1天和2天后灌注。总共使用9个点和11条线性测量来分析石膏模型以及负性和正性数字模型。分别评估藻酸盐印模随时间的变形以及传统石膏模型和数字模型的准确性。
石膏模型、负性和正性数字模型在T（0）、T（1）和T（2）时间的几乎所有测量中均显示出显著差异（P < 0.01、P < 0.05和P < 0.001）。牙弓周长测量在T（0）和T（1）时间没有差异（P > 0.05），但在T（2）时间模型之间显示出统计学上的显著差异（P < 0.05）。
本研究表明，与正性数字模型和石膏模型的测量相比，负性数字模型的测量具有高度的有效性；技术之间的差异在临床上是可接受的。对印模进行直接扫描对正畸医生来说是一种可行的方法。
