A Comparative Evaluation of Digital and Conventional Approaches in Orthodontic Space and Tooth Size Analysis: A Retrospective Comparative Study

Aim of the study was to comparatively assess the sensitivity of digital measurements for space discrepancies and tooth size analysis in comparison to conventional plaster models, digital models, and rescanned plaster models. Orthodontic pre-treatment records were obtained from 40 randomly selected patients undergoing orthodontic treatment in the permanent dentition (mean age: 20.83; 14 males, 26 females). Intraoral 3D records and conventional plaster models were collected. Digital measurements were performed using an intraoral scanner (iTero Element, Align Technologies, San Jose, Calif), while conventional measurements were derived from alginate impressions used to create plaster models. These plaster models were subsequently digitized using the same intraoral 3D scanner. All measurements from the digitized models were analyzed using the OrthoCAD software (Cadent, Carlstadt, NJ, USA). No significant differences were observed among the groups for measurements of Hayes-Nance Maxilla Actual, Hayes-Nance Maxilla Required, Hayes-Nance Maxilla Discrepancy, Bolton Overall Maxilla, Bolton Overall Mandible, Bolton Overall Discrepancy, Bolton Overall Ratio (%), Overbite, and Overjet (p>0.05). Throughout the study, no variations were observed in Hayes-Nance, Bolton analyses, or overjet-overbite measurements across digital models, plaster models, and digitized plaster models. The mean differences between methods were generally within 1 mm, suggesting clinical comparability for most analyses. However, moderate intra-examiner reliability was observed for Bolton Anterior Ratio and Overbite, indicating that these variables should be interpreted with caution. Within the limitations of this study, scanning plaster models with an intraoral scanner appears to be a feasible and clinically acceptable alternative to direct digital scanning.