Functional occlusion after fixed appliance orthodontic treatment: a UK three-centre study

This study aimed to assess the prevalence of functional occlusal contacts in cases treated to a Class I incisor relationship by upper and lower fixed appliance therapy. Helkimo's dysfunction indices were used by one examiner to assess mandibular mobility, clinical dysfunction and occlusal status. One-hundred-and-eighty-eight subjects participated in three UK orthodontic centres; Cardiff, Newport and Liverpool. The results show that RCP (CR)-ICP (CO) discrepancies occurred in 33 (18 per cent) cases, non-working side contacts were present in 31 per cent and posterior contacts on protrusion occurred in 44 (23 per cent) subjects. These interferences were significantly more frequent in cases treated by postgraduate students compared with those treated by staff clinicians (P < 0.05). An overbite greater than 2.4 mm resulted in a highly significant reduction in the occurrence of non-working side contacts and posterior protrusive contacts (P < 0.001). The prevalence of functional occlusal discrepancies in this UK sample of orthodontic cases is similar to that reported in the American literature.