Discrepancies in Occlusal Contact Relationship in 12-year-old Children in SA

The study forms part of a larger study to determine the prevalence of malocclusion in 12-year-old SA children using the DAI. Objective: The purpose of this part of the study was to determine the prevalence and severity of occlusal contact relationship discrepancies in 12-year-old SA children. Method: The sample comprised 6351, 12-year-old children from 7 provinces in SA. According to Proffit et al, two major types of malocclusion occur, intra-arch irregularities and malalignment, and discrepancies in occlusal contact relationship. In the DAI, occlusal contact relationships are defined in terms of the variables: anterior maxillary overjet, anterior mandibular overjet, vertical anterior openbite and antero-posterior molar relation. Results: Of the 6351 children, 90.5% presented with anterior maxillary overjet and 9.5% with anterior mandibular overjet. According to Moyers an overjet between 1mm and 3mm is considered normal. The results of the current study indicate that 57.2% of the subjects with maxillary overjet presented with a normal overjet, 11.1% with a 0mm overjet (edge-to-edge) and 31.7% with an overjet larger than 3mm. Anterior openbite, which is a lack of vertical overlap between any of the opposing pairs of incisors, was present in 7.7% of the sample. The size of the openbite ranged from 1 to 8mm. The assessment of antero-posterior molar relation was based on the relationship of the permanent upper and lower first molars. Only the largest deviation from Angle Class I was recorded. The results indicate that 44.5% of the sample presented with an antero-posterior molar relationship discrepancy. Of these, 30.2% presented with a half a cusp displacement and 14.3% presented with a full cusp displacement. Conclusions: Antero-posterior molar relationship discrepancies (44.5%) were the most prevalent form of occlusal contact relationship discrepancy followed by increased overjet (42.8%), mandibular overjet (9.5%) and anterior openbite (7.7%) in 12-year-old SA children.