Effect of stabilization of patients on the accuracy and scanning time of maxillary dentate quadrants: A clinical study

Abstract

Statement of problem

As intraoral scanning has gained widespread acceptance as an alternative to conventional impression-making, numerous studies have evaluated the influence of operator-related factors and patient-related factors on scanning accuracy. While several authors have noted patient movements as a clinical limitation of scanning technologies, research providing empirical data or testing this hypothesis is lacking.

Purpose

The purpose of this clinical study was to assess the effect of using the Zero Motion Scanning Band, a silicone occlusal mouth prop, and an OptraGate lip retractor for stabilizing the head and jaw on the accuracy (trueness and precision) and scanning time of digital quadrant scans.

Material and methods

A conventional impression was made of the maxillary right quadrant with polyvinyl siloxane material and then digitized using a calibrated extraoral scanner to create the reference file. Two different groups were created: no scanning aids (NSA) and with scanning aids (WSA). For the NSA group, scans were made without considering the participant’s movements. For the WSA group, scans included the Zero Motion Scanning Band, a silicone occlusal mouth prop, and an OptraGate lip retractor. Sixty-four scans were captured with an intraoral scanner (TRIOS 3) for each group, and the scanning time was recorded. Using an inspection and metrology software program, scans of each group were superimposed on the reference file to determine 3-dimensional (3D) deviations. The Kolmogorov-Smirnov test evaluated the normality of the distribution of variables, and the Mann-Whitney U test was selected for data analysis of non-normally distributed variables, including 3D deviations and scanning time (α=.05).

Results

Significant differences for trueness and scanning time mean values were observed under different scanning conditions: with and without head and jaw positioning (P<.05). The modified scan protocol exhibited higher trueness, with smaller mean root mean square values of 38.4 ±2.7 µm compared with 40.8 ±3.1 µm in the nonmodified group. However, precision did not display a statistically significant difference with varying scanning conditions (P>.05).

Conclusions

The use of the Zero Motion Scanning Band, a lip retractor, and a silicone occlusal mouth prop on the contralateral side of the scanned quadrant significantly improved the trueness and scanning time of the quadrant digital scan. Further evaluation of head and jaw stabilizing tools is recommended in more complex clinical scenarios, such as complete arch digital scans and scanning implant-supported restorations.