Document Type: Original Article

Authors

1 Assistant Professor, Department and Orthodontics, Dental School, Shiraz University of Medical Sciences

2 Assistant Professor, Iran University of Medical Sciences

Abstract

Most malocclusions have a vertical component, as well as, anterior-posterior malrelationship.Information about the vertical balance and the importance of growth in strategic sites of the face is emphasized as a determining factor in successful treatment. Most experienced clinicians agree that, malocclusions with marked vertical facial imbalance, are generally more difficult to treat and treatmentresults is definetly harder to maintain than the primarily ant-post discrepancies.Openbite is the result of abnormal vertical development, that is inufficient to permit teeth to meet their antagnoists, in the opposite arch. The ethiology of openbite generally may be:1) Disturbances or mechanical interferences with eruption and alveolar growth and 2) Skeletal Imbalance.In this study by utilizing of openbite definition, a group of 2365, 9-11 years old students in Shiraz primary schools were examined clinically and also by cephalomentric evaluation.Prevalence of anterior openbite was found to be about 3.08%, which was slightly, greater for female group.Correlating openbite with sagital discrepancy, children with CL.II occlusion were affected more frequently than children with CL.I and CL.III occlusion. Other results were as follow:1) It was found that, UFH/LFH ratio was less for openbite subjects, upper face height is almost normal but lower face height was sufficiently greater so as to make the total face height of openbite subjects greater than that of normal subjcts.2)Jarabak Index significantly decreased.3)The SN-MP and PP-MP angle were greater than normal.4)The Saddle, Articular and Gonial angles were increased which is a determining factor of vertically growth pattern of openbite subject.5)SN-GOGN angle had a high correlation with basal plane angle, occlusal-mand. plane, SNOcclusaland jarabak, therefore, these angular measurements, could be known to be reliable in the assesment of facial growth pattern and also and indication of the effect of mandibular position inanterior posterior and/or in vertical discrepancies.