Accuracy of Bolton analysis measured in laser scanned digital models compared with plaster models (gold standard) and cone-beam computer tomography images

Abstract

Objective: The aim of this study was to compare the accuracy of Bolton analysis obtained from digital models scanned with the Ortho Insight three-dimensional (3D) laser scanner system to those obtained from cone-beam computed tomography (CBCT) images and traditional plaster models.

Methods: CBCT scans and plaster models were obtained from 50 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner; Bolton ratios were calculated with its software. CBCT scans were imported and analyzed using AVIZO software. Plaster models were measured with a digital caliper. Data were analyzed with descriptive statistics and the intraclass correlation coefficient (ICC).

Results: Anterior and overall Bolton ratios obtained by the three different modalities exhibited excellent agreement (> 0.970). The mean differences between the scanned digital models and physical models and between the CBCT images and scanned digital models for overall Bolton ratios were 0.41 ± 0.305% and 0.45 ± 0.456%, respectively; for anterior Bolton ratios, 0.59 ± 0.520% and 1.01 ± 0.780%, respectively. ICC results showed that intraexaminer error reliability was generally excellent (> 0.858 for all three diagnostic modalities), with < 1.45% discrepancy in the Bolton analysis.

Conclusions: Laser scanned digital models are highly accurate compared to physical models and CBCT scans for assessing the spatial relationships of dental arches for orthodontic diagnosis.

Keywords: Dental cast analysis; Digital models; Three-dimensional scanner.

Figure 1. Screenshot of imported scanned digital models using Ortho Insight three-dimensional software (Motionview Software LLC., Hixson, TN, USA).

Figure 2. Mesiodistal tooth width automatically calculated after digital separation of the teeth and automatic facial axis detection using Ortho Insight three-dimensional software (Motionview Software LLC., Hixson, TN, USA).

Figure 3. Landmarks represented by arrows on a cone-beam computed tomography (CBCT) slice (left) and a digitally bisected three-dimensional model obtained from the CBCT scans (right) using Avizo software (standard edition version 6.0; Mercury Computer System Inc., Chelmsford, MA, USA).