Is mandibular posterior dento-alveolar intrusion essential in treatment of skeletal open bite in adult patients? A single center randomized clinical trial.

BACKGROUND: Anterior open bite (AOB) malocclusion usually represents a complicated and advanced orthodontic problem. The skeletal variant of AOB used to be treated with a combined orthodontic and surgical approach, until the posterior segments' intrusion has been validated as an alternative, effective and conservative treatment modality for such cases with comparable outcomes to the surgical approach. The objective of this two-arm parallel randomized clinical trial was to compare the effects of mini-screw supported maxillary versus bi-maxillary buccal segments' intrusion on the amount of anterior open bite closure. METHODS: Twenty-two adult patients aged 17-25 years, with skeletal open bite and anterior dental separation of 3-8 mm were randomized to either the comparator (Maxillary Intrusion with Consolidation of mandibular buccal segments-MIC) or intervention (Bimaxillary buccal segments' intrusion-BMI) groups. Miniscrew-assisted buccal segments' intrusion was instituted using fixed appliances on rigid stainless steel archwires (19 x 25 stainless steel) via nickel-titanium coil springs in the maxilla and memory chains in the mandible. The intrusion force was 200 g per maxillary buccal segment in both groups, and it was 150 g for each mandibular posterior segment in the BMI group. Duration of intrusion was 6 months. RESULTS: Anterior open bite was significantly closed in both groups with means of 3.8 +/- 0.84 (95% confidence interval [CI] 3.2-4.4) and 3.84 +/- 1.47 mm (CI;2.8-4.9) for the MIC and BMI groups, respectively with no significant difference between them (p-value < 0.05). Maxillary posterior teeth experienced significant intrusion in both groups, with a mean of 2.89 +/- 1.13 mm (CI;2.63-3.14) in the MIC group and 2.26 +/- 1.62 mm (CI;1.89-2.62) in the BMI group. Statistically significant mandibular posterior teeth intrusion occurred in both groups with means of 0.86 +/- 0.91 (CI;0.65-1.06) and 0.33 +/- 0.84 mm (CI;0.14-0.52) in the BMI and MIC groups, respectively, with a statistically significant difference of 0.53 +/- 0.14 (CI;0.25-0.8) mm. However, such difference was considered clinically insignificant. CONCLUSIONS: Anterior open bite closure could be successfully achieved with maxillary buccal segments intrusion without the need for active intrusion of the mandibular posterior segments, as long as the latter are efficiently consolidated. TRIAL REGISTRATION: The trial was prospectively registered at clinicaltrials.gov with an identifier number of NCT04713280.