No abstract available.
Malocclusion* ; Malocclusion, Angle Class I* ; Molar*

No abstract available.

No abstract available.
Animals ; Bone Resorption* ; Dinoprostone* ; Rats* ; Tooth Movement* ; Tooth*

By observing the correlationships between the characteristics of the facial pattern and the methods of establishing the position of the lower central incisor to the five reference lines on the lateral roentacenocephalograms, the author tried to fine the most useful method of them, the criteris of which were the independence of a vatiation according to facial patterns, the close rslationships with soft tissue and lip balance, and the simple and consistent usefulness in clinical practice. The subject consisted of forty normal occlusions, forty class II div 1 malocclusion, forty class III malocclusions, ten treated class II div 1 cases and ten treated class III cases, all were in 14-17 yrs of age. The findings of this study are as follows: 1. The position of the lower central incisor to FP, OP, MP and NB showed variations according to ANB, FMA, Facial convesity and holdaway angle. 2. The position of the lover central incisor to AP line (A-Pog) was not correlated with ANB, FMA, Facial convexity and Holdaway angle, so it can be used consistently, regardlesss of the facial pattern. 3. The linear position of the incisal edge of the lower central incisor to AP line has a profound influence on harmonious soft tissue and lip balance.
Incisor* ; Lip ; Malocclusion

This study was undertaken to investigate the degree of asymmetry in each part of the head in skeletal craniofacial asymmetric patients, and secondarily to determine the nature of difference existed between asymmetric patients and normal persons. The subjects consisted of 49 asymmetric adult patients and 52 normal adults, and the average ages were 21 years 5 months and 23 years 5 months, respectively. The computerized analyses of 33 linear measurements, 12 angular. measurements, and 8 surface areas from posteroanterior cephalometric radiograph were carried out. The conclusions were as follows; 1. Asymmetry was a common finding in both normal and asymmetric group. 2. When the analyses were undertaken after the head was divided into 3 parts anteroposteriorly and superoinferiorly in the asymmetric patients, there were significant asymmetries in all parts excepts in the cranial base region. 3. When the analyses were undertaken after the head was divided into respective 3 parts anteroposteriorly in the asymmetric patients, the more posterior part showed relative stability than the more anterior part. 4. When the analyses were undertaken after the head was divided into 3 parts superoinferiorly in the asymmetric patients, the more superior part showed relative stability than the more inferior part. 5. Twelve variables indicating asymmetry were selected and the highest ranked variable was Me-Mid-sagittal reference line.
Adult ; Head ; Humans ; Skull Base

No abstract available.
Animals ; Electromagnetic Fields* ; Magnets* ; Rats*

This experiment was designed to study possible roles of interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha in bone remodeling by measuring their effects on PGE2, LTB4 and collagenase production when they were administered to human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were collected from first premolars extracted for orthodontic treatment. They were incubated in the environment of 37degrees C, 5% CO2, and 100% humidity. They were treated with 0.25% trypsin-EDTA solution and centrifuged. PDL cells in the fifth to seventh passage were used for the experiment. Cells were seeded onto the culture dishes and when they were successfully attached, human recombinant interieukin-lbeta, interleukin-6, and tumor necrosis factor-alpha were administered, alone or in combination. They were incubated for 4, 8 and 24 hours and the levels of PGE2, LTB4 and collagenase released into the culture media were assessed by enzymeimmunoassay and collagenase activity assay. The conclusions are as follows: 1. IL-1beta and TNF-a were very active in stimulating the production of PGE2 and collagenase by human periodontal ligament fibroblasts, while IL -6 increased LTB4 production. 2. IL-1beta significantly increased PGE2 , but LTB4 production was not increased. IL-1beta is thought to act mainly via the cyclooxygenase pathway of arachidonic acid metabolism. 3. IL-6 tended to inhibit IL- 1beta in the production of PGE2 and collagense whereas IL-6 and TNF-alpha showed additive effect in the level of PGE2. The above cytokines increased the release of at least one of PGE2, L TB4 and collagenase. It suggests that cytokines are involved in bone remodeling process by stimulating PDL fibroblasts to produce various bone-resorptive agents. The roles of cytokines in bone remodeling as a whole would need further study.
Arachidonic Acid ; Bicuspid ; Bone Remodeling ; Collagenases* ; Culture Media ; Cytokines* ; Dinoprostone* ; Fibroblasts* ; Humans* ; Humidity ; Interleukin-1beta ; Interleukin-6 ; Leukotriene B4* ; Metabolism ; Periodontal Ligament* ; Prostaglandin-Endoperoxide Synthases ; Tumor Necrosis Factor-alpha

Vascular changes in the periodontal ligament of the rat incisors following application of experimental orthodontic forces were examined by the India ink perfusion method. 57 rats were used for this experiment. The rats were divided into experimental group (54 rats) and control group (3 rats). 54 experimental rats were divided into group I (27 rats) and group II (27 rats). The right and left upper incisors of group. I and group II rats were separated distally with forces of 20gm, 70gm respectively. The vascular changes of periodontal ligament were observed histologically by means of light microscope after 1,2 and 3 days of tooth movement and 1,3,5,8,14, and 21days after removal of orthodontic force. The results were as follows; 1. After one day of tooth movement, occlusion of blood vessels, hyalinization of periodontal ligament and resorption of alveolar bone adjacent to the alveolar crest on pressure side were observed. Above the tissue changes on the pressure side of group II were more severe than those of group I. Especially, septal bone of group II was separated after 2 days of tooth movement. 2. In tension zones, periodontal space was widened and periodontal fibers were orientated in the direction of pull. The blood vessels of periodontal ligament were distended. New bone deposition was seen along the inner surface of the alveolus after 2 days of tooth movement. 3. After 3 days of tooth movement, deposition of new bone was seen along the periosteal surface of alveolar bone on pressure side, progressing with increasing after removal of orthodontic force. Remodelling of the new bone was occurred 5 days after removal of orthodontic force. 4. 3 days after removal of orthodontic force, invasion of blood vessels into the marginal periodontal ligament on pressure side was observed clearly and the vessels below the epithelial attachment were increased. 5. After removal of orthodontic force, hyalinized structures disappeared concomittantly with an invasion of blood vessels from the neighboring periodontal ligament. 14 days after removal of orthodontic force, the vessels in the periodontal ligament of group I were finished the vascular rearrangement. 21 days after removal of orthodontic force, the vessels in the periodontal ligament of group II were finished the vascular rearrangement.
Animals ; Blood Vessels ; Epithelial Attachment ; Hyalin ; Incisor* ; India ; Ink ; Perfusion ; Periodontal Ligament ; Rats* ; Tooth Movement* ; Tooth*

The purpose of this study was to evaluate and compare frictional forces generated between orthodontic brackets and arch wires. Independent variables were chosen for study: arch wire size and shape, arch wire material, bracket width, and second-order angulation between bracket and arch wire. Kinetic frictional forces of stainless steel (0.014", 0.016", 0.018", 0.016" x 0.022", 0.018" x 0.022"), beta-titanium (0.016" x 0.022") arch wires were measured on wide and junior edgewise twin brackets (0.018" x 0.022" slot). Instron was used to pull arch wires while 0degrees, 3degrees, 6, or 9degrees angulation between and wire and bracket was given. The results were as follows: 1. The frictional force of beta-titanium wire was larger than that of stainless steel wire. 2. The frictional force was generally increased as the size of wire is increased. 3. The frictional force of rectangular wire was larger than that of round wire. 4. As second order angulation was increased, the frictional force was also increased. 5. The frictional force was larger on a wide bracket than on a junior bracket.
Friction* ; Humans ; Orthodontic Brackets* ; Stainless Steel ; Tooth*

The purpose of this study was to evaluate treatment effects of bionator in Class II division 1 malocclusion by FEM(Finite Element Method). The 73 subjects were classified into good result group and poor result group in reference to posttreatment molar relation, posttreatment overbite and overjet, posttreatment profile, and relapse. Pretreatment and posttreatment lateral cephalograms were taken and FEM was performed. The results were as follow; 1. There was no statistical significance in treatment changes between the sexes, and between the treatment result groups. 2. Treatment changes were not significantly different among the age groups. 3. The effect of treatment period groups on skeletal and dentoalveolar changes were analyzed using ANOVA. Body of maxilla, upper incisor, anterior face, ramus, upper anterior face, lower anterior face and treatment effect were correlated with the treatment period, but correlation coefficients were low. 4. The results of present investigation confirm that Class II bionator can assist in the correction of Class II division 1 malocclusion, mainly due to dentoalveolar changes. 5. There is significant difference in skeletal and dentoalveolar pattern between good result group and poor result group. In poor result group, maxilla was relatively downward and backward rotated, mandible was relatively backward rotated, upper incisor was in relatively lingual position, lower incisor was in relatively labial position.
Activator Appliances* ; Humans ; Incisor ; Malocclusion* ; Mandible ; Maxilla ; Molar ; Overbite ; Recurrence