Avaliação do efeito do uso do arco lingual em pacientes com diferentes tipos faciais : análise em telerradiografia de perfil

Abstract

The Nance lingual arch is widely used in preventive and interceptive orthodontics, and its main objective is to maintain lower arch length in cases of premature loss of deciduous teeth or mild to moderate crowding during the change from a mixed dentition to permanent dentition. Objectives: To perform a literature review addressing aspects related to the uses of the lingual arch and its effect on the dentition, as well as to evaluate and compare the effect of the lingual arch in patients with vertical and horizontal growth patterns. Materials and methods: Linear and angular measurements were performed using cephalograms of 41 patients (21 horizontal and 20 vertical patients) after the use of the lingual arch for a period of 12 ± 3 months. A control sample of 21 patients was used to compare the effect of the lingual arch. The Kolmogorov-Smirnov normality test and Student's T test for dependent samples to compare before and after treatment were used. Student's T-test for independent samples was used to compare experimental group vs. control group and vertical vs. horizontal patients. In order to evaluate the reliability of the measurements, the Intraclass Correlation Coefficient (ICC) was calculated. The measures evaluated were: angular incisor, angular molar, angular second molar; vertical molar, vertical incisor, arch length and sagittal displacement of the incisor and molar. Results: The control group had a decrease in arch length of 1 ± 1.2 mm and the experimental group lost only 0.2 ± 1 mm (p = 0.01). There were no significant differences between experimental group and control for the other measures. When comparing vertical and horizontal patients, the only measure that showed statistically significant diference was the angular second molar. The lower second molars showed distal inclination in the horizontal type and a mesial inclination in the vertical type (p <0.05). Conclusion: The lingual arch was effective to control arch length during the study period. There was no difference in the effect of lingual arch between vertical and horizontal patients, except for second molar angulation. Mesial angulation of the second molar is related to greater chance of impaction. Vertical patients during the use of the lingual arch need to be monitored regarding the risk of impaction of the second permanent molar.