Vertical changes during Begg’s and PEA-A Comparative Study

Abstract

The purpose of this study was to compare the vertical dimensional changes in bialveolar dental protrusion patients undergoing extraction of all four first premolars between the preadjusted edgewise appliance(PEA)(MBT) and the Begg appliance. The cephalometric records of 40 patients with Class I bimaxillary protrusion were selected and devided in two groups i.e Begg or PEA mechanotherapy. The age group of 18-25 years was selected for both groups. Skeletal and dental changes were analysed in both groups on lateral cephalograms taken pre (T1)& post (T2) treatment. A student t-test was used to analyse the treatment changes. Significant increase in face height and extrusion & mesial movement of lower molars within both groups were found. However no significant difference was found when the Begg mechano-therapy was compared to PEA Technique on vertical dimensional changes. I. Introduction Extraction of teeth has always been the primary method of gaining space for either correction of severe crowding or retraction of proclined teeth. It also helps in closing the bite in open bite subjects and has therefore been suggested as a method of controlling the vertical dimension of the face. The vertical dimension of the face increased following orthodontic treatment as the molars were extruded because of inter-arch mechanics, which consequently caused clockwise rotation of the mandible. Further fuelling this controversy, Cusimano and McLaughlin (1993) and Upadhyay et al. (2008) suggested that occlusal movement of the posterior teeth tends to keep pace with the increase in anterior face height, thus maintaining the mandibular plane angle and nullifying any bite-closing effect of protraction of the posterior teeth. Swain and Ackerman (1969) and Williams (1977) reported considerable molar extrusion under the influence of Class II elastics. However, James (1968) and Thompson (1972) found that with the Begg appliance, the deep bite was corrected primarily by simultaneous extrusion of the mandibular molars and intrusion of the lower incisors. It was suggested that molar extrusion might lead to a backward rotation of the mandible increasing the vertical facial dimension with a potentially detrimental effect on facial aesthetics. The aim of this research was to evaluate and compare the changes in the vertical facial dimension in Angle Class I bimaxillary dentoalveolar protrusion subjects on an underlying Class I or mild Class II skeletal base treated with first four premolar extractions with the Begg or PEA(MBT) technique.