The measurement threshold and limitations of an intra-oral scanner on polished human enamel

Objective. To investigate the measurement threshold of an intra-oral scanner (IOS) on pol-ished human enamel. Methods. The optical performance of an IOS was compared to a gold-standard non con-tacting laser profilometer (NCLP), on a painted microscope slide, compared to increasing particle size of silicon-carbide papers (21.8-269.0 & micro;m) and separately on polished human enamel with increasing step-heights. The enamel samples were randomised (n = 80) and scanned using the IOS and NCLP at increasing step-height depths (& micro;m) (1.87-86.46 & micro;m) and quantified according to ISO:5436-1. The measurement threshold of the IOS was determined using a custom designed automated lesion localisation algorithm, corroborated by Gaussian skewness (Ssk) and kurtosis (Sku) analysis, to assess the minimum step-height measured on each enamel sample. Results. The NCLP showed statistically increased Sq surface roughness for all silicon carbide particle sizes compared to the microscope slide, whereas, the IOS Sq roughness discrim-inated silicon-carbide particles above 68.0 & micro;m compared to the glass slide (p <= 0.02). On polished enamel, the automated minimum detectable step-height measurable on each sample was 44 & micro;m. No statistically significantly different step-height enamel lesion mea-surements were observed between NCLP and IOS above this threshold (p > 0.05). Significance. This study revealed the fundamental optical metrological parameters for the IOS, was step-heights above 44 & micro;m and this reflects the data acquisition of the system. These results highlight the limitations of IOS used in this study, mandating further research to optimise the performance of other IOS systems, for measuring wear of materials or tooth wear on human unpolished natural enamel surfaces. (c) 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Automated summary

This study investigated the measurement threshold of an intraoral scanner on polished human enamel, revealing a threshold of 44 micrometers for accurate measurements. The results showed no significant differences in enamel lesion measurements between the non-contacting laser profilometer and the intraoral scanner above this threshold.