Etiology of Class II Division I Malocclusion

BACKGROUND: Throughout the history of modern orthodontics there has been debate as to the effect of treatment upon both the dento-alveolar and skeletal relationships in a Class II Division I Malocclusion. With Cephalometric analysis we are able to examine these interactions in greater detail. OBJECTIVE: Our study evaluated the changes from start to retention in the treatment of Class II Division I patients, relative to the mean data of a clinically normal occlusion. METHODS: Cephalometric data was collected on 74 patients at the start of treatment and retention phase. Both sets of data were related to the mean data of Class I occlusion. The mean data for each measurement for start and retention series, was related to the mean data for clinically normal occlusions. The number of patients who exhibited numbers greater than 1 standard deviation were recorded for both start and retention sets of data which were compared to each other for all 38 measurements taken to investigate the effect of treatment of this malocclusion upon the maxillofacial structures. RESULTS: Patients chin in an AP relationship with FH more similar to that of a Class I. Patients Profile Less Convex than at the Start of Treatment, more similar to Class I. Position of Molar in Maxilla more similar to that of Class I. Position of Molar in Maxilla more similar to Class I in proportion of the effective length of Mx. CONCLUSIONS: There are differences between the Class II Division I start and retention means for numerous measurements when compared to that of Class I occlusions. Fewer patients are outside of 1 standard deviation of the clinically normal means when treatment of the Class II Division I malocclusion is complete. More is occurring than just movement of teeth, there is a change to a more Class I skeletal relationship.