Mesiodistal tooth angulation to segmental occlusal plane in panoramic radiography / 대한구강악안면방사선학회지

PURPOSE: To evaluate the stability of the segmental occlusal plane and anatomical line as the reference line for measuring the mesiodistal tooth angulation in panoramic radiography and to determine the mean angle and the range of the mesiodistal tooth angulation in Korean population with normal occlusions. MATERIALS AND METHODS: Twenty nine subjects (15 men, 14 women) with normal occlusion were selected. A total of 29 panoramic radiograms were taken at normal head position and then 10 images of 5 subjects selected were repeatedly taken with repositioning 2 times at each of the head down (V-shaped occlusion) and up (horizontal occlusion) for evaluation of stability of adopted reference lines by using PM2002CC (Planmeca, Finland). The images were traced with adoption of two test reference lines and the long axes of the teeth. The mesial angles formed by each reference line and the long axes of the teeth were measured and analyzed. RESULTS: With anatomical reference line, the mesiodistal tooth angulations of the molars showed the significant difference by over 5 degree between the normal and each changed head position. With segmented occlusal reference line, deviations of mesiodistal tooth angulations by the two changed head positions were less than 1 degree. The means, standard deviations, and maximum and minimum values of mesiodistal tooth angulations to segmental occlusal reference line on panoramic radiography were determined. CONCLUSION: It would appear that mesiodistal tooth angulations to segmental occlusal plane as reference line in panograms are predictable as standards of normal occlusion and useful for evaluation of tooth arrangement between adjacent teeth.

Cleidocranial dysplasia: a case report / 대한구강악안면방사선학회지

Cleidocranial dysplasia is a rare and autosomal dominent disorder characterized by aplasia or hypoplasia of the clavicles, an open fontanelle, dental abnormalities, and short stature. A 17-year-old female who presented with short stature and subsequent delay in eruption of permanent teeth is described. she showed the abnormal hypermobility of the shoulder, ocular hypertelorism and concave nasal bridge. Radiographs revealed the underdeveloped maxilla, defect of the cranium in the fontanelle region, and aplasia of the clavicles. Characteristically, panoramic view revealed near parallel-sided borders of the ascending ramus and downward curvature of the zygomatic arch with hypoplasia. The prolonged retention of deciduous teeth with delayed eruption of permanent teeth and multiple embedded supernumerary teeth were striking. Radiographic and clinical investigations revealed Cleidocranial dysplasia.

The radiographic localization of unerupted maxillary incisors and supernumeraries / 대한구강악안면방사선학회지

PURPOSE: To evaluate the use of the vertical tube shift from a panoramic film and a periapical film to localize unerupted maxillary incisors and supernumeraries. MATERIALS AND METHODS: The total of 103 displaced maxillary incisors or embedded supernumeraries were examined in this study. The vertical tube shift technique with panoramic and periapical radiography by normal projection taken and compared to localize the position of the embedded maxillary incisors or supernumeraries by a radiologist and 5 general dentists. The gold standard used for the radiographic comparisons was the true position of the embedded tooth as confirmed by horizontal tube shift technique using three periapical radiographs. The general dentist examiners were instructed on the use of the modified acronym "SLDOBU" by the radiologist as it pertains to panoramic radiographs as the principle of vertical tube shift. RESULTS: All of the embedded maxillary incisors and supernumeraries were successfully located using the vertical tube shift from a panoramic and a maxillary anterior periapical radiograph by the radiologist and 5 general dentists. CONCLUSION: The use of a panoramic film with a periapical film combination for a vertical tube shift can be useful to localize unerupted maxillary incisors and supernumeraries.

Reference line for computed tomogram of the mandible / 대한구강악안면방사선학회지

PURPOSE: This study was performed to determine the proper reference line for taking axial computed tomograms from which the good cross-sectional views can be reformatted by multiplanar reconstruction. METHODS: Three dry mandibles with implanted gutta percha cones in the extracted socket were scanned axially according to 6 reference lines of 2 mandibular positions with computed tomogram Hitachi W550. The accuracy of measurements of the lengths of implanted gutta percha cones in the each cross-sectional view reformatted from axial computed tomogram by multiplanar reconstruction was evaluated. RESULTS: The difference between the measurements and the real length of implant was smallest in the bucco-lingual views reformatted from the axial views scanned according to the reference line of group V-a. The smaller the angle difference between reference line and occlusal line was, the smaller the difference between the measurements in the bucco-lingual views reformatted from axial views and the real length of implant. The majority of measured widths of implants in the bucco-lingually reformatted views were larger than the actual values. CONCLUSIONS: When the mandible is inclined within the limitation of gantry angle and scanned with the reference line coincident with occlusal plane, the bucco-lingual view can be reformatted without deformation of images from the axially scanned images.

Reference line for computed tomogram of the mandible / 대한구강악안면방사선학회지

PURPOSE: This study was performed to determine the proper reference line for taking axial computed tomograms from which the good cross-sectional views can be reformatted by multiplanar reconstruction. METHODS: Three dry mandibles with implanted gutta percha cones in the extracted socket were scanned axially according to 6 reference lines of 2 mandibular positions with computed tomogram Hitachi W550. The accuracy of measurements of the lengths of implanted gutta percha cones in the each cross-sectional view reformatted from axial computed tomogram by multiplanar reconstruction was evaluated. RESULTS: The difference between the measurements and the real length of implant was smallest in the bucco-lingual views reformatted from the axial views scanned according to the reference line of group V-a. The smaller the angle difference between reference line and occlusal line was, the smaller the difference between the measurements in the bucco-lingual views reformatted from axial views and the real length of implant. The majority of measured widths of implants in the bucco-lingually reformatted views were larger than the actual values. CONCLUSIONS: When the mandible is inclined within the limitation of gantry angle and scanned with the reference line coincident with occlusal plane, the bucco-lingual view can be reformatted without deformation of images from the axially scanned images.