Agreement of digital and conventional maxillary arch-length and intermolar-width measurements in children aged 7 to 12

Background: Digital dental models are increasingly used in children, but their agreement with conventional cast measurements for arch-length and intermolar-width assessment remains unclear. This study compared conventional and digital workflows for intermolar width and arch-length assessment in maxillary models and evaluated workflow-level agreement between them. Methods: Maxillary models from 60 untreated children aged 7–12 years with Angle Class I molar relationships were evaluated. On plaster casts, intermolar width and arch length were measured with a digital caliper. The same casts were then digitized and analyzed using dedicated software. Intraobserver repeatability of conventional measurements was assessed with intraclass correlation coefficients and Dahlberg’s formula. Agreement between conventional and digital measurements was evaluated using Bland–Altman analysis. Results: The mean difference in arch length was 1.46 mm with 95% limits of agreement ranging from −6.5 to +9.5 mm, while the mean difference in intermolar width was 0.67 mm with 95% limits of agreement ranging from −3.1 to +4.4 mm. Conclusions: The digital workflow showed closer agreement with the conventional workflow for intermolar width than for arch length; however, the observed limits of agreement indicate that the two workflows should not be assumed to be interchangeable for individual patient-level decisions without clinical caution. For arch length, the wider limits of agreement likely reflect, at least in part, the non-equivalent geometric definitions used by the two workflows.

Mixed dentition; Digital dental model; Arch length; Intermolar width; Bland–Altman analysis

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