An Evaluation of Validity of Measurements using Digital Caliper and Three-dimensional Virtual Dental Models

Lee, Joo Hoon; Paik, Ki Suk; Chang, Mi Sook; Lee, Seung Pyo

Abstract

The measurement of tooth and the space analysis of dental study models are essential for precise diagnosis and treatment plan for orthodontic or prosthodontic cases. Traditionally, these have been done on study models with instruments, such as a divider or a caliper. At present, three-dimensional (3-D) virtual dental models are available for clinicians, supplemented by dedicated software for performing needed measurements on them. For example, Autoscan system for dental application(TM) (ASDA; INUS technology INC, Korea) is one of these systems using a non-contact 3- D scanner. The accuracy of this system has been tested and validated by the Korea Testing Laboratory. However, the outline of dental models is not simple and has many undercuts. Therefore, we sought to evaluate the accuracy of measuring models using digital calipers or ASDA to compare these two techniques. From each ten study models, 10 duplicated stone and 10 virtual models were generated. Virtual models were scanned from duplicated model because of revival of clinical situation. Then, central incisors, canines, first molars, arch (intercanine and intermolar) width of original model were measured by a digital caliper, and the same items of virtual models were measured by software. All measurements were performed twice by two experienced observers. Data were statistically analyzed by 2-way Analysis of Variance (2-way ANOVA, SPSS Ver. 11.5). The results from this study have demonstrated that virtual model is highly valid and reliable for measuring both tooth size and arch width. Although some values of virtual model are higher or lower than original dental model, the significance value is still higher than 0.97. A digital caliper seems to be a more precise instrument to perform a scientific work, ASDA's accuracy is clinically acceptable. Furthermore, considering its present advantages and future possible applications, the examined or equivalent 3-D virtual models may become the standard for clinical use.