A modification to the incisor classification of malocclusion

During the study of two-hundred orthodontic cases under treatment in the General Dental Service, four clinicians showed only moderate agreement using the British Standard Classification of Incisor Malocclusion. Cohen's Kappa statistic was used to measure the inter-examiner agreement. The 35 cases in which there was high disagreement between the examiners were scrutinized to determine the source of this disagreement. Following discussion, revised definitions were produced which included the introduction of a Class II-intermediate group. After an interval of 2 months these 35 cases were reclassified using the new definitions. Increased inter-examiner agreement was found. Four examiners (three of whom were common to the original study) then used the modified classification to describe the incisal relationship of 100 cases referred for treatment at Bristol Dental Hospital. The inter-examiner and the intra-examiner agreement were both found to be good. It is recommended that the Incisor Classification of Malocclusion be extended to include a Class II-intermediate group.