Treatment results and long-term stability of anterior open bite malocclusion

OBJECTIVES: To evaluate treatment results and long-term stability of anterior open bite malocclusion and to identify predictive factors for both treatment results and their stability. DESIGN: Retrospective study. SETTING AND SAMPLE POPULATION: The Department of Orthodontics and Oral Biology at the Radboud University Nijmegen Medical Centre, The Netherlands. Fifty-two patients with an anterior open bite. METHODS: Lateral cephalograms and dental casts were analysed at: start of treatment (Ts), end of treatment (T0), 2 and at least 5 years after the end of treatment (T2 and T5, respectively). A standard cephalometric analysis was performed, while the Peer Assessment Rating (PAR) index was used to evaluate the occlusion. RESULTS: The mean PAR reduction at T0 was 74%, but decreased to 56% at T5. The mean overbite (OB) increased from -3.2 mm (+/- 1.9) at Ts to 0.4 mm (+/- 1.1) at T0, 0.1 mm (+/- 1.6) at T2 and 0.2 mm (+/- 1.8) at T5. Thirty-seven patients (71%) had a positive OB at T0, but the bite opened again in 10 of these patients (27%) from T0 to T5. Forty-four per cent of our patients had an open bite at T5. No pre-treatment variables could predict these changes. CONCLUSION: Treatment response and long-term stability of the anterior open bite was found to be rather poor. This has to be taken into consideration when planning treatment of open bite patients. Prediction of open bite closure at the end of active treatment or at the follow-up was not possible.