The effectiveness of clear aligners in levelling the curve of Spee and related maxillofacial factors in patients with a deep overbite

Abstract

Abstract Introduction To guide deep overbite treatment, the effectiveness of clear aligners and the influence of maxillofacial characteristics were assessed in levelling the curve of Spee (COS). Methods Forty-two patients underwent phased treatment using clear aligners. Digital dental models were created before and after treatment following which predicted outcomes, and dental cast measurements were conducted in addition to the analysis of lateral cephalometric and panoramic radiographs. The anticipated COS correction was compared with the actual correction achieved. Using multiple linear regression, associations between levelling effectiveness and clinical indicators were evaluated to establish prediction equations. P = 0.05 indicated statistical significance. Results The levelling effectiveness was 71.8 ± 19.0%. The regression model accounted for 88.5% of the variance in levelling effectiveness (F-value = 167.209, adjusted R 2 = 0.885, Akaike information criterion [AIC] [E]=-146.94). The levelling effectiveness was related to the vertical skeletal pattern, the angulation of the mandibular incisors to the mandibular plane, the axial inclination of the mandibular anterior teeth, and the pre-treatment COS depth. Levelling effectiveness and other maxillofacial variables were not significantly related. Conclusion Clear aligners effectively level the COS. Patients with a larger Frankfort-mandibular plane angle, a pre-treatment COS depth, and an incisor-mandibular plane angle, more easily achieved COS levelling using clear aligners. Those with smaller mandibular incisor parallelism still achieved effective levelling.