[The effect on chewing of treating distal bite with an activator]

The aim of this study was to analyse the influence of activator treatment on chewing efficiency. The subject material consisted of 60 children, adolescents and adults: Twelve children (ten years of age) with a Class II, Division 1 malocclusion were treated successfully with activators to a normal occlusion (16 years of age). Three normal occlusion samples, ten years (n = 12), 16 years (n = 12) and 29 years (n = 12) of age as well as an untreated Class II sample (n = 12), 16 years of age, served as control groups to the activator patients. The chewing ability was evaluated with the aid of a chewing efficiency test. The dental occlusion was appraised on dental casts. Recordings were made of number of erupted teeth, number of intermaxillary occlusal tooth contacts, overjet and overbite. The results revealed that chewing efficiency in activator patients was doubled from ten to 16 years of age. When comparing untreated subjects 16 years and ten years of age a greater chewing efficiency was seen in the older subjects. This was true for both Class II malocclusion and normal occlusion cases. Furthermore, in 16 year old subjects the chewing efficiency was comparable in treated and untreated normal occlusions as well as untreated Class II malocclusions. Thus, the investigation did not ascertain whether activator treatment per se resulted in an improved chewing efficiency. Furthermore, in the activator group no direct association existed between improvement in chewing efficiency and increased number of erupted teeth on one hand and increased number of intermaxillary occlusal tooth contacts, reduced overjet and overbite on the other. It is suggested that chewing efficiency is partly age related. The sagittal intermaxillary dental arch relationship doesn't seem to play an important role in determining chewing ability. However, harmonious interplay between the occluding teeth and the muscles influencing them (the muscles of mastication, the tongue-, lip- and cheek-musculature) is certainly of importance.