Expansão rápida da maxila: estudo longitudinal de 10 meses

Abstract

This thesis is composed of two scientific papers. Article I aimed to evaluate the effects of rapid maxillary expansion (RME) on sleep disorders in children with maxillary atresia using a case series longitudinal study. Article II evaluated the use of low-level laser (LLL) aplications as an adjuvant in RME regarding its effects on the bone repair of the midpalatal suture, and on the stability of the upper intermolar distance, through a randomized clinical trial. The study sample consisted of 27 patients, aged between 8 and 12 years, in the mixed dentition, with maxillary atresia, who underwent RME with a Hyrax expander. In the first study the patients were evaluated using a questionnaire answered by their guardians, the Sleep Disturbance Scale in Children (SDSC), at the following time points: T0 (pre-treatment phase), T1 (day of stabilization expansion screw), T2 (3 months after screw stabilization), T3 (immediately after removing the expander, after 6 months of retention) and T4 (3 months of post-retention). Poisson multilevel analysis adjusted for repeated measures was performed. RME influenced the reduction of SDSC total scores, and were statistically significant from T2 onwards, and below the cutoff point for risk of sleep disorders at T4. In Article II, the patients in the sample were randomly divided into two groups: laser group, n = 13, who underwent RME and LLL in the region of the midpalatal suture; and control group, n = 14, RME and LLL placebo. Ten LLL sessions were performed within a 35-day interval. At each session, 10 points were irradiated over the midpalatal suture and laterally to it. Bone density in the anterior region of the midpalatal suture was evaluated on occlusal digital radiographs, using the ImageJ software, using a grayscale at the following time points: T1, T2, T3 and T4; and the transverse stability of maxillary expansion was evaluated from the intermolar distance in millimeters using Meshmixer software, at time points T0, T1 and T4. Multilevel Poisson regression analysis was performed. The effect size for bone density was greater in the laser group, indicating greater bone repair in this group. Already the effect size for upper intermolar distance greater in the control group from T1 to T4, indicating a greater orthodontic relapse in this group, but with no statistically significant difference in both outcomes. In conclusion, RME had a positive effect on the reduction in SDSC total scores as of 3 months of screw stabilization. Although the proposed protocol trended toward benefitting the group irradiated by LLL, bone repair in the midpalatal suture and stability in the upper intermolar distance showed no clinical or statistical differences between the groups.