An effective approach to assessing inter-root distances using tooth models without repeated cone-beam computed tomography scans during orthodontic treatment

Objective: To propose the utilization of virtual tooth models (VTMs) created by combining tooth root data from cone-beam computed tomography (CBCT) and crown data gathered through intraoral scanning to assess inter-root distance and angulation during orthodontic treatment when repeated radiographic monitoring becomes necessary. Methods: Patients with planned dental implant placement in edentulous areas during or after orthodontic treatment and who underwent intraoral and CBCT scans at the pretreatment and posttreatment stages were selected. Tooth models were fabricated by merging intraorally scanned crowns with the corresponding CBCT-scanned roots from the pretreatment. Tooth positions posttreatment was estimated by integrating models into posttreatment intraoral scans. Moreover, the actual positions were obtained from posttreatment CBCTs. Discrepancies in the estimated and actual tooth positions, including interradicular distances and inter-root angulations, were compared. Results: The minimum inter-radicular distance between two adjacent teeth demonstrated no significant difference between the estimated and actual tooth positions. The difference in inter-root angulation was not statistically significant. Most interradicular distances measured at each landmark revealed no significant differences between the estimated and actual tooth positions, except at the buccolingual midpoint of the cemento-enamel junction, where a slight discrepancy was observed. Conclusions: The tooth position of VTMs demonstrated clinically acceptable accuracy compared to CBCT scans. Additionally, VTMs can benefit both clinicians and patients by enabling accurate assessment of the inter-radicular space for dental implant placement without repeated CBCT scans.