RÉSUMÉ
Objective:To assess the long-term stability of leveling the curve of Spee after at least 8 years post-treatment in patients with mesocephalic pattern. Material and Methods:Measuring the depth of the curve of Spee in 10 mesocephalic patients at the following times: T0 (before the beginning of orthodontic treatment), T1 (at the end of orthodontic treatment) and T2 (at least 8 years after orthodontic treatment). These measures were compared using paired t-test (significance level of 5%). The curve depths were calculated from the measures of the distances between the lower buccal cusp of the posterior teeth of each side to a reference surface, which was supported by 3 points of the lower cast. Results:The mean curve of Spee depth at T0 was 1.86 mm, 0.50 mm at T1 and 0.53 mm at T2. The mean correction of the curve of Spee depth was 1.36 mm (73.11%) and the average relapse was 0.03 mm (2.2%). No statistically significant differencebetween T1 and T2 values in left or right sides was found. On the other hand, significant differences among T0 and T1 and T0 and T2 values were found. Conclusion:The results suggest that there was no significant depth relapse of the curve of Spee and also that leveling the curve is a stable procedure after 8 years after treatment in mesocephalic patients still using mandibular fixed retainer. The values found when comparing the depth in T0 and T1 showed that the curve of Spee was leveled during orthodontic treatment