Comparison of treatment changes in overjet and jaw base relationship with removable and fixed functional appliances

Abstract

AIM: To compare changes in overjet and jaw base relationship during treatment and follow-up of skeletal Class II malocclusion subjects. MATERIALS AND METHOD: A series of lateral cephalograms obtained from a group of consecutive male patients treated with headgear-activator (RFA) for 12 months was compared with a matched group treated with a Herbst appliance for 6 months, followed by ‘retention’ with an Andresen activator for six months (FFA). The patients were then followed for a further 24 months. Lateral cephalograms were obtained at start of treatment, after 6 and 12 months of treatment, and after another 24 months, and analysed (Pancherz, 1982). Interpolations were made to obtain data representing exactly the same length of observations periods. RESULTS. During the initial 6 months of treatment the jaw base relationship improved significantly more in the FFA than the RFA group; the difference of 1.5 mm being statistically significant (P < 0.05). After 12 months of treatment (RFA) and treatment and retention (FFA), there was no significant difference in the change of jaw base relationship between the two groups, and neither so at 24 months follow-up. After 6 months of treatment the overjet reduction was 5.7 mm greater (P < 0.001) in the FFA group than in the RFA group. At 12 months the RFA group showed a continued reduction in overjet whereas relapse occurred in the FFA group, the difference of 3.4 mm was statistically significant (P < 0.001). At the 24 month follow-up the difference in overjet change was 1.6 mm (ns). CONCLUSION: The FFA seems to offer only short-term advantages with regard to changes in overjet reduction and jaw base relationship compared with the RFA. The observed superiority in the initial phase did not persist long-term.