An epidemiologic study on the orthodontic patients who visited department of orthodontics, Chosun university dental hospital last 10 years (1990-1999) / 대한치과교정학회지

With socioeconomic development and change of esthetic recognition, the demand for orthodontic treatment and number of orthodontic patients has been increasing so rapidly. And frequency of malocclusion was changed. So this study was done in an attempt to provide an epidemiologic study so that we can accomodate their orthodontic needs adequately and to obtain the reliable quantitative information regarding the characteristics of orthodontic patients. Distribution and trends were examined in 3,070 malocclusion patients who had been examined and diagnosed at Department of Orthodontics, Dental Hospital, Chosun University over 10 year-period from 1990 to 1999. The results were as follows : 1.The number of patients per year was increasing trend and higher visiting rate in female(56.5%) than in male(43.5%). 2.Age distribution had shown 7~12 year-old group being the largest(37.9%) and each percentage of 13~18, 19~24, above-19, 0~6 year-old group was 32.0%, 19.6%, 7.1%, 3.4%. 3. Hellman dental age IVa which is completion of the permanent dentition showed the highest percentage in male and female. 4.Geographic distribution showed a majority of patients in Kwang Ju(71.0%). Group within the distance 10km from Chosun Dental Hospital was 56.3% and group within 20km was 14.7%. 5.Anterior cross bite showed the highest percentage in chief complaints and percentage of Mn. prognathism and protrusion of Mx. teeth was 12.6%, 12.2%. 6.Distribution in the types of malocclusion according to the Angle's classification had shown; 38.9% for Class I, 20.7% for Class II division 1, 2.0% for Class II division 2, 38.4% for Class III. 7.In the dental vertical dysplasia according to the Angle's classification, deep bite was the most frequent in Class II div.1 and div. 2(24.3%, 56.7%) and open bite in Class III(21.4%). 8.In the skeletal sagittal dysplasia, 39.3% of skeletal ClassII was due to the undergrowth of the mandible and 46.3% of skeletal ClassIII was due to the overgrowth of the mandible. 9.Distribution in orthodontic treatment accoding to the extraction and nonextraction had shown 66.9% for nonextraction case, 33.1% for extraction case, and four first bicuspids have been extracted in the highest percentage(38.6%). 10.Patients who had orthognathic surgery comprised 7.9%, with an increasing trend.

Changes of lateral cephalometric values according to the rotation of head / 대한치과교정학회지

This study was performed to find out the effect projection errors on cephalometric linear and angular measurements according to head rotation during taking lateral cephalometric radiography. Seventeen skulls with permanent dentition and on gross asymmetry were obtained from the Department of Anatomy, Medical School, Chosun University. Total 527 x-ray films were taken with 1degrees interval from the reference position(0degrees) to 15degrees around the vertical axis (Z axis) which is perpendicular to the midpoint of the connecting the center of two ear rods in submento-vertex direction. Statistical analysis was performed by paired t-test if there were statistically significant differences between the mean of the reference position(0degrees) and that of each rotation angle. The following results were obtained. 1. The projection errors of angular measurements were smaller than those of linear measurements. 2. The projection errors of angular measurements including midline landmarks were smaller than those including bilateral landmarks. 3. The horizontal linear measurements were gradually decreased when the skull was rotated toward the film, but slightly increased and then decreased when the skull was rotated toward the focal spot. However, the changes were smaller in focal direction. 4. The projection errors of horizontal linear measurements were larger than those of vertical linear measurements. 5. The projection errors of vertical linear measurements were increased with increased distance form the rotation axis to vertical measurements. It is concluded that the use of angular measurements rather than linear measurements is recommended to minimize the projection errors.