Microscrew anchorage in skeletal anterior open-bite treatment.

OBJECTIVE: To evaluate the effectiveness of miniscrew anchorage for intrusion of the posterior dentoalveolar region to correct skeletal open bite.

MATERIALS AND METHODS: The study was comprised of 12 patients (aged 14.3 to 27.2 years; mean 18.7 years) with anterior open bites. All the patients presented a Class II skeletal pattern and excessive posterior growth. Self-drilling miniscrew implants were inserted into the posterior midpalatal area and the buccal alveolar bone between the lower molars. A transpalatal and a lingual arch were used to maintain the molars on each side in order to avoid overrotation during intrusion. A force of 150 g was applied to the microscrews on each side to intrude the posterior teeth. Lateral cephalograms of all 12 patients were taken preintrusion and immediately after completion of the intrusion. The cephalometric films were measured and compared.

RESULTS: The results showed that the anterior open bites in 12 patients were all corrected in a mean of 6.8 months. Overbite increased by a mean of 4.2 mm (P < .001), from -2.2 mm in preintrusion to 2.0 mm in postintrusion. The maxillary and mandibular first molars were intruded for an average of 1.8 mm (P < .001) and 1.2 mm (P < .001), respectively. The mandibular plane angle was reduced by 2.3 degrees (P < .001), which led to a counterclockwise rotation of the mandible with a significant decrease in the anterior facial heights (mean of 1.8 mm; P < .001).

CONCLUSION: Miniscrew anchorage has the advantages of being a simpler procedure, being minimally invasive, and requiring minimal patient cooperation.