Begg light-wire treatment of a severe Class II cross-bite malocclusion

Abstract

I n the treatment of a Class 11, Division 1 malocclusion, attention is usually directed toward correcting the anteroposterior relationship of the dental arches and the vertical relationship of the anterior teeth. The third dimensionthe lateral relationship-is not often at fault. When a severe lateral discrepancy in the arches is present, however, treatment may be made much more complicated. Such a discrepancy may be due to a lateral deviation in the path of closure of the mandible, resulting from an initial contact of teeth, or to a basic discrepancy in the widths of the maxilla and mandible. If the discrepancy is so severe that the upper and lower buccal teeth do not meet, excessive vertical development of the buccal segments on the affected side may occur, giving rise to a progressively deteriorating traumatic occlusion. This report deals with a 12-year-old girl who was examined in January, 1971. She was diagnosed as having a Class II dental base relationship, crowding localized to the labial segments, an increased overjet, an increased complete overbite, and a buccal cross-bite on the right (Fig. 1) . The third mola.rs were developing normally. Treatment was directed toward relief of crowding, reduction of the overjet and the overbite, and establishment of a good buccal occlusion. The patient was treated according to the principles and method outlined by &ix. Recorded measurements were taken from tracings of preand post-treatment cephalometric lateral skull films and from models. The following features were assessed by means of measurements on standardized lateral skull radiographs with the use of the following landmarks (Fig. 2) : anterior nasal spine (ANS) , menton (M), gonion (G), incisal edge of the lower central incisor (I), tip of the lower first permanent molar (L), tip of the upper first permanent molar (U), maxillary plane (MxP)-a line joining the anterior and posterior nasal spines, mandibular plane (MP)-a line passing through menton and gonion.