Functional jaw orthopaedics for management of Class II division 1 malocclusion

Abstract

Malocclusion is a deviation from rarely attained ideal arrangement among teeth (normal occlusion) that does not necessarily cause a functional problem [1]. Class II Division 1 malocclusion is characterised by the mandibular dentition “distal” to the maxillary dentition; the malrelation may be due to a basic osseous dysplasia or due to forward movement of the maxillary dental arch and alveolar processes or combination of skeletal and dental factors. The purpose of dentofacial orthopaedics is to modify the pattern of facial growth and the underlying bone structure of the face. The objective is to promote harmonious facial growth by changing the functional muscle environment around the dentition. The principle of functional therapy is to reposition a retrusive mandible to forward position by constructing an appliance with a protrusive bite when the appliance is placed in the mouth. The mechanics are reversed to correct a retrusive maxilla, but the principle remains the same [2]. The twin block appliance (TBA), described by William J Clark in 1982, is considered the most successful functional appliance in the treatment of Class II division 1 malocclusion. [3]. The TBA incorporates the use of upper and lower bite blocks, interfacing at 70° to achieve the desired forward position of the mandible and redirect occlusal forces to achieve rapid correction of malocclusion.