Orthopedic Correction of Growing Hyperdivergent, Retrognathic Patients With Miniscrew Implants

Abstract

Traditional orthodontic treatments do not adequately address the skeletal problems of retrognathic, hyperdivergent, Class II adolescents; the few approaches that do require long-term patient compliance. This paper introduces a novel approach using miniscrew implants (MSIa) and growth to treat retrognathic hyperdivergent adolescents. Nine consecutive patients were evaluated at the start of treatment (13.2 ±1.1 years of age) and again at the end of the orthopedic phase (after 1.9 ±0.3 years). Each patient had two MSIs placed in either side of the palate. Coil springs (150 g) extended from the MSIs to a RPE, which served as a rigid segment for intruding the maxillary premolar and molars. Two additional MSIs were placed between the first mandibular molars and second premolars; coil spring (150 g) extended from the MSIs to hold or intrude the mandibular molars. Prior to treatment, the patients exhibited substantial and significant mandibular retrusion (Z-score=−1.0), facial convexity (Z-score=0.7), and hyperdivergence (Z-score=1.6). Treatment produced consistent and substantial orthopedic effects. The chin was advanced an average of 2.4 mm, the SNB angle increased by 2.1°, the mandibular plane angle decreased 3.9°, and facial convexity decreased by approximately 3.2°. Questionnaires showed that this treatment approach was not painful or uncomfortable; the majority of the patients indicated that they were very likely to recommend the treatment to others. Treatment was accomplished by titrating the amount of orthodontic intrusion performed based on the individuals' growth potential.

Dentoskeletal changes following mini-implant molar intrusion in anterior open bite patients

“…Buschang et al (2011) 5 reported a pilot study of nine adolescent patients, but ours is the first paper to report both skeletal and dental changes resulting from molar intrusion in adolescent patients. Treatment at an earlier chronological age, coincident with adolescent growth, showed statistically significant correlations with the changes in OB, OP-SN, and SNB.…”

“…However, it is possible to successfully correct AOB with the adjunctive use of temporary skeletal anchorage. [1][2][3][4][5][6][7][8] It has been suggested that palatal alveolar miniimplants, coupled with a customized rigid transpalatal arch provides optimal chances for mini-implant stability and molar intrusion, especially in patients with higharched palates. 9,10 Several studies have investigated the total effects of molar intrusion, but the results have included additional mandibular molar intrusion and vertical maxillary and mandibular molar (occlusal) settling following both the intrusion phase and treatment completion.…”

Mechanical stability and clinical applicability assessment of novel orthodontic mini-implant design

“…14,15 Recently, mini-implants have been applied with palatal expanders to achieve greater sutural expansion. 8,16 With the broadened application of the mini-implants used in orthodontics, there is a need to examine the stability of these implants under various clinical conditions.…”

Translational mini-screw implant research

“…This has opened the possibility of using MSIs for posterior intrusion and indirect mandibular autorotation. For example, a prospective, feasibility study was designed by Buschang et al (2011) to produce vertical facial reductions by intruding segments of teeth in a controlled fashion using MSIs. This novel approach using MSIs and growth to treat retrognathic, hyperdivergent adolescents showed a very favourable response, with advancement of the chin, the SNB angle increased, the mandibular plane angle decreased, and facial convexity decreased.…”