The contemporary use of removable orthodontic appliances.

Although apparently simple and efficient to use, removable appliances are no longer the appliance of choice for comprehensive orthodontic treatment in the permanent dentition. Their mechanical properties result in simple tipping of teeth, therefore multiple simultaneous tooth movements with apical control are not possible. It is for these and other reasons that removable appliances are usually only indicated for specific interventions in the mixed dentition, and as an adjunct to more complex fixed appliance treatment. Removable appliances, once popular because of their case of use, are no longer seen as the appliance of choice. This article discusses the rationale behind this statement and indicates cases suitable for removable appliance treatment.

A randomized clinical trial to compare three methods of orthodontic space closure.

AIM: To compare the rates of orthodontic space closure for: Active ligatures, polyurethane powerchain (Rocky Mountain Orthodontics, RMO Europe, Parc d'Innovation, Rue Geiler de Kaysersberg, 67400 Illkirch-Graffenstaden, Strasbourg, France) and nickel titanium springs. SAMPLE: Patients entering the space closure phase of fixed orthodontic treatment attending six orthodontic providers. Twelve patients received active ligatures (48 quadrants), 10 patients received powerchain (40 quadrants) and 11 patients, nickel-titanium springs (44 quadrants). METHOD: Patients were randomly allocated for treatment with active ligatures, powerchain or nickel titanium springs. Upper and lower study models were collected at the start of space closure (T(o)) and 4 months later (T(1)). We recorded whether the patient wore Class II or Class III elastics. Space present in all four quadrants was measured, by a calibrated examiner, using Vernier callipers at T(o) and T(1.) The rate of space closure, in millimetres per month (4 weeks) and a 4-monthly rate, was then calculated. Examiner reliability was assessed at least 2 weeks later. RESULTS: Mean rates of space closure were 0.35 mm/month for active ligatures, 0.58 mm/month for powerchain, and 0.81 mm/month for NiTi springs. No statistically significant differences were found between any methods with the exception of NiTi springs showing more rapid space closure than active ligatures (P < 0.05). There was no effect of inter-arch elastics on rate of space closure. CONCLUSIONS: NiTi springs gave the most rapid rate of space closure and may be considered the treatment of choice. However, powerchain provides a cheaper treatment option that is as effective. The use of inter-arch elastics does not appear to influence rate of space closure.