A matter of Class: interpreting subdivision in a malocclusion.

Confusion exists in the orthodontic community regarding the meaning of subdivision in Angle's classification system. The purpose of this study was to survey orthodontic educators in the United States to determine their viewpoint on the meaning of subdivision and to ascertain the criteria on which they base their interpretations. Fifty-seven surveys were mailed to department chairs in the United States, asking them to identify the definition to which their orthodontic residency program subscribes; 34 surveys were returned. Twenty-two responses supported the notion that subdivision refers to the Class II side, 8 responses said that it refers to the Class I side, 3 responses supported neither view, and 1 response indicated that not everyone in the program could agree on the meaning of subdivision. Although the prevailing belief appears to be that subdivision indicates the side with a molar malocclusion, the orthodontic community does not have a consistent standard, and it is time to resolve this controversy.