การเปรียบเทียบการวิเคราะห์ระยะที่ว่างบนแบบจำลองดิจิทัลกับแบบจำลองปลาสเตอร์

Abstract

Objectives (1) to evaluate the differences of linear measurement on dentoform with conventional method and digital models (2) to evaluate the differences of linear measurement on digital models, which created from direct scanning of dentoform, the impression scanning and the plaster cast replicas scanning and (3) to evaluate the differences of space analysis in various groups with different severity of crowding on digital models obtained by three scanned processes compared with those taken from plaster models. TM Materials and methods Part 1: a plastic dentoform was marked for 24 reference points and direct measured linear distances with a digital caliper. Digital models were created from the plastic dentoform with three processes by direct scanning the dentoform, impression scanning and plaster cast replica scanning with 3Shape R700T scanner. Measurements of linear distances were made for all three groups of digital models with 3Shape OrthoAnalyzer. Comparison the differences of linear measurement made directly on dentoform and digital models obtained from direct scanning and the differences of linear measurement made directly on three groups of digital models were done. Part 2: 120 upper and lower plaster models of patients were divided into four groups according to the severity of crowding (group 1: no crowding, group 2: <2 mm, group 3: 2-4 mm, group 4: >4 mm) and those were converted to digital models by three different scanning methods: direct scanning using 3Shape R700T scanner, impression scanning and plaster cast replica scanning. Tooth size and arch length measurement were performed on both plaster models by the using of digital caliper and digital models with the using of 3Shape OrthoAnalyzerTM. Space discrepancy for each study model was calculated. The comparison of the tooth size, arch length and space discrepancy measurement made directly on plaster models and made on all three groups of digital models were done. Results Part 1: Statistically significant differences were found between the measurements made directly from the dentoform and digital models (P<0.05) as 19 from 24 observations. The measurements on digital model were greater than the measurements on dentoform but just slightly as 0.08-0.41 mm. Statistically significant differences were found among three groups of digital models (P<0.05) only 4 from 24 observations. The differences were slightly just around as 0.11-0.23 mm. Part 2: No statistically significant differences were found between plaster and digital model measurement for the sum of tooth size, arch length and space discrepancy measurement in any of the various groups of crowding. (P≥0.05) Conclusion Although there were statistically significant differences between the measurements made directly from the dentoform and digital models but the differences were slightly and considered no clinical significant. Therefore, the use of digital models appears to be acceptable in linear, tooth size, arch length and space analysis measurement.