Research Article: Adaptation and validation of the Wylie cephalometric analysis for three-dimensional assessment of canine occlusion in Labrador retrievers
Abstract:
In veterinary medicine, we lack a quantitative method for assessment and classification of occlusion. Current systems of occlusion classification are subjective, limiting the ability for precise treatment planning.
A medical record search identified 146 head CTs from Labrador Retrievers from 2007–2022. 3D computer models of skulls were created from DICOM files. Thirty standardized anatomic landmarks were placed on each model to perform cephalometric analysis. A cohort of 96 dogs was used to establish breed-specific reference values, with assessment for sexual dimorphism prior to standardization. The remaining 50 dogs served as a validation cohort for the Wylie cephalometric analysis to quantify maxillomandibular length discrepancy. Facial angles analysis and three ratio-based measurements (MXPM4: MNM1, MXK9: MNK9, and MX: MN) were calculated for all samples.
Craniofacial measurements showed significant sexual dimorphism and showed allometric scaling with weight. There was no significant difference between normalization and validation groups. Wylie score clustered near zero (SD?=?3), indicating minimal maxillomandibular discrepancy in dogs with normal occlusion. The mean ANB angle was 7.8°?±?1.5°. Ratio-based measurements assessing maxillary-to-mandibular relationships were as follows: MXPM4: MNM1 ratio was 1.1, the MXK9: MNK9 ratio was 0.9, and the MX: MN ratio was 1.0 across all individuals. The ratio-based measurements correlated strongly with the Wylie score.
Human cephalometric analyses can be adapted for use in canine patients. This study established a reference standard for cephalometric analysis in Labrador Retrievers as a representative of mesaticephalic canine skulls. The Wylie analysis and ratio-based measurements represent a quantifiable method of occlusion assessment.
Introduction:
In veterinary medicine, we lack a quantitative method for assessment and classification of occlusion. Current systems of occlusion classification are subjective, limiting the ability for precise treatment planning.
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