Accuracy of Mandibular Dentition Distalisation With Invisalign in Class III Malocclusion: A Pilot Study Using CBCT Superimposition

OBJECTIVE: By integrating digital models with cone beam computed tomography (CBCT) images and registration on stable hard tissue regions for superimposition, we aimed to enable a more precise and detailed analysis of Invisalign treatment on Class III malocclusion. MATERIALS AND METHODS: Digital models of 12 Class III adults at pretreatment (T1) and posttreatment (T2) were integrated with maxillofacial CBCT images. The T1 and T2 CBCT images were superimposed using voxel-based registration of stable cranial base structures to assess the three-dimensional movement of the maxillary teeth and positional changes of the mandible. Mandibular tooth movement was evaluated by superimposition of the mandibular CBCT images, registered on the symphysis and mandibular body. The virtual planning model created by ClinCheck was superimposed based on its position relative to the T1 digital model. RESULTS: The median accuracy of distal movement for the mandibular first molar cusps ranged from 26.72% to 33.87%. With miniscrew anchorage, the accuracy ranged from 39.28% to 44.66%. Actual distal movement averaged 0.62 ± 0.82 mm to 0.80 ± 0.89 mm with Class III elastics, and 2.02 ± 1.71 mm to 2.29 ± 1.53 mm with miniscrews. The maxillary incisors significantly proclined more with Class III elastic traction. No significant positional changes in mandibular anatomical landmarks were observed during treatment with miniscrew anchorage, whereas the use of Class III elastics led to significant positional changes in the condyle head. CONCLUSION: Invisalign treatment may not reach the expected efficacy in mandibular dentition distalisation, especially when skeletal anchorage is absent.