Intrusion of the maxillary posterior teeth with a single buccal mini-implant positioned bilaterally in young adults with a tendency towards hyperdivergence: A clinical study

Abstract

Background: Skeletal anchorage systems have been used for intrusion of the posterior teeth with satisfactory results. To achieve this, mini-implants are placed at anatomically challenging sites such as the palate or require several mini-implants to produce the desired effect. Objective: To determine the magnitude of intrusion of the maxillary posterior teeth achieved on a continuous arch wire using a single buccal mini-implant placed bilaterally in young patients with a tendency towards hyperdivergence and to evaluate its influence on the skeletal, dental and soft-tissue structures. Methods: A total of 17 patients with proclination of the anterior teeth, tendency towards hyperdivergence and clockwise rotation of the mandible were selected. First premolars were extracted as part of treatment protocol. A 0.022-MBT bracket prescription was used. Mini-implants were placed bilaterally on the buccal aspect at the mucogingival junction or slightly gingival to it between the maxillary second premolar and first permanent molar. A total of 200 g of intrusive force was placed from a continuous 0.019 × 0.025 inch stainless-steel arch wire to the mini-implant by means of an elastomeric thread on both sides. Lateral cephalograms and study models were taken before the start of intrusion and six months later. Parametric and non-parametric tests were done to assess treatment results. Results: Significant intrusion was observed in the maxillary molar and premolar region with tendency towards intrusion in the anterior region. There was significant decrease in lower anterior facial height (LAFH) with anti-clockwise mandibular rotation, decrease in facial proportion index and total facial height. No changes were observed in the transverse plane. Conclusion: Intrusion of the permanent maxillary molar can be achieved on a continuous arch wire with a single buccal mini-implant placed bilaterally with improvement in facial aesthetics, especially in the vertical plane. This method may be beneficial in patients with borderline vertical discrepancy treated with conventional friction mechanics during space closure after first premolar extractions.