Long-term stability of anterior open bite treatment with bonded spurs in the mixed dentition: a secondary data analysis from a clinical trial.

This study evaluated the stability of anterior open bite (AOB) treatment with bonded spurs (BS) after 4 years of follow-up. The BS group included 26 patients (9 male, 17 female) in the mixed dentition with Class I or Class II malocclusion and AOB, treated with BS for 1 year. Lateral cephalograms were taken at pretreatment (T1, 8.06 years), post-treatment (T2, 9.11 years) and 4-year post-treatment (T3, 13.3 years). The control group comprised 20 untreated subjects (7 male, 13 female) with AOB. The primary outcome was the overbite change. Interphase cephalometric comparisons in the BS group were performed with repeated measures ANOVA followed by Tukey or Friedman test (P < 0.05). Intergroup comparisons were performed with t-tests, Mann-Whitney, and Chi-square tests (P < 0.05). Multiple linear regression analysis evaluated the influence of initial AOB severity and facial growth pattern on long-term overbite changes. During the follow-up, the BS group showed a slightly increase in overbite (0.87 ± 1.17 mm). Two patients (7.69%) demonstrated relapse with negative overbite (mean: -2.75 mm) at T3. During treatment, the BS group showed greater overbite increase (4.53 ± 1.55 mm), incisor extrusion (2.72 1.25 mm), and lingual tip of upper (2.72 ± 1.25°) and lower incisors (-2.24±3.61°) compared to the control group. Neither initial AOB severity nor facial growth pattern significantly influenced long-term overbite changes (P = 0.831). Ethnic heterogeneity between the BS and control groups, and the use of a historical control group, which made randomization impossible. Another limitation is the absence of data on the etiological habits in the control group. Bonded spurs are effective for anterior open bite treatment in the mixed dentition, providing a high rate of long-term stability (92.31%).