Effect of clear aligners on distalization of maxillary first molars in mixed dentition and early permanent dentition: a retrospective study.

BACKGROUND

The differential impact of maxillary first molar distalization on the three-dimensional displacement of the maxillary second molars during crown formation (Nolla 4-6 stages) and root development (Nolla 7-8 stages) remains unclear. Furthermore, the influence of two stages on the three-dimensional displacement of the first molars and central incisors, as well as the actual distal displacement and displacement rate of the first molars requires further investigation.

METHOD

36 patients were equally divided into Nolla 4-6 stages group ( aged 8.50 ± 0.92 years) and Nolla 7-8 stages group ( aged 11.27 ± 0.67 years). CBCT data were analyzed before and after distalization. Normally distributed data were analyzed using paired sample T-tests, with significance set at P < 0.05.

RESULT

(1) After distalization in Nolla 4-6 and Nolla 7-8 stages groups, the first and second molars showed buccal movement, distobuccal rotation and crown distal inclination (P < 0.05). Proclination of the maxillary central incisors was found. (2) Compared to Nolla 4-6 stages group, the degree of distobuccal rotation and crown distal inclination of second molars, distobuccal rotation of first molars and proclination of central incisors were smaller and the realization rate was larger in Nolla 7-8 stages group (P < 0.05).

CONCLUSIONS

Clear aligners can effectively distalize maxillary first molars when second molars are unerupted. However, the movement of molars and central incisor, the actual displacement and realization rate of first molars are different in Nolla 4-6 and Nolla 7-8 stages. Treatment plans should be tailored to the developmental stage of the second molars to enhance efficiency and ensure optimal dental and maxillofacial health in children.