Bimaxillary protrusion as a pathologic problem in the Thai.

The purpose of the study was to determine the nature and occurrence of bimaxillary protrusion in seventy-five students of the Faculty of Dentistry, University of Chiangmai, Thailand. The average age of the subjects was 22 years. Growth and development of facial dimensions were in a relatively stable configuration. Procedures included an evaluation of cephalographs, models, and photographs and an analysis of habits. A Steiner's analysis revealed the significance of the interincisal relationship for bimaxillary protrusion. In all cases the interincisal angle was below 124 degrees. In comparison with cases having an interincisal angle above 124 degrees, there was an increase in problems such as mouth breathing and tongue and lip habits, as well as a relative increase in tongue volume. Results of the study indicate that the etiology of bimaxillary protrusion is complex, involving environmental factors, soft-tissue function, volume, and habit.