The purposes of this study were: 1) to determine the normal range of CR-CO discrepancy in normal occlusion group: 2) to evaluate the changes of condylar position and craniofacial morphology between centric relation and centric occlusion before and after stabilization splint therapy in malocclusion group outside the normal range of CR-CO discrepancy. The normal occlusion group consisted of 80 subjects who had well-balanced faces and good occlusions with acceptable Class I molar relationship. They had not been treated orthodontic ally and had no signs or symptoms of temporomandibular joint dysfunction. 71 malocclusion patients enrolled for orthodontic treatment at the Department of Orthodontics, College of Dentistry, Chosun University comprised the malocclusion group, little variation of growth factor by the second molar eruption. They had CR-CO discrepancy beyond normal range and were subdivided into anterior-posteriorly -[25 Class I (0 or = 4), and 24 Class III (ANB < or = 0)]; vertically - [20 Normodivergentscy (30 or = 34), and 18 Hypodivergency (SNGoMe < or = 30)] ; and sexually - [26 Male and 45 Female]. For malocclusion group, stabilization splint with mutually protected type of occlusal scheme was applied for three months. Panadent articulators, Panadent condylar position indicator (CPl), and lateral headfilm were used to investigate the influence of stabilization splint on condylar position and craniofacial morphology. The results of this study were as follows: 1. The amounts of CR-CO discrepancy in normal occlusion were that the antero-posterior component (delta X) was 0.56 +/- 0.46mm (Male: 0.63 +/- 0.42rnm, Female: 0.49 +/- 0.50mm) ; the supero-inferior component (delta Y) was -0.75 +/- 0.48rnm (Male: -0.76 +/- 0.52rnm, Female: -0.73 +/- 0.43rnm) ; and the transverse component (delta Z) was -0.33 +/- 0.28mrn (Male: -0.38 +/- 0.29mm, Female: -0.31 +/- 0.27mm). 2. The condylar position was in normal range after stabilization splint therapy. 3. The mandible was always rotated infero-posteriorly after stabilization splint therapy. 4. Antero-posteriorly, Class III malocclusion responded very well to the stabilization splint therapy. 5. Vertically, Hyperdivergency responded very well to the stabilization splint therapy. 6. Sexually, Male responded very well to the stabilization splint therapy.
Centric Relation ; Dental Articulators ; Dentistry ; Female ; Humans ; Male ; Malocclusion ; Mandible ; Molar ; Orthodontics ; Reference Values ; Splints* ; Temporomandibular Joint

The purpose of this study was to evaluate the characteristics of craniofacial skeleton on orthognathic surgical cases with skeletal Class III malocclusion. For this study, 74 students at the dental college of Chosun University volunteered as a normal occlusion group. They had well-balanced faces and good occlusions with acceptable Class I molar relationship. They had not received orthodontic treatment and had no signs or symptoms of temporomandibular joint dysfunction. 45 malocclusion patients enrolled for orthognathic surgical treatment with skeletal Class III malocclusion at the Department of Orthodontics, College of Dentistry, Chosun University. On the basis of this study, the results of this study were as follows: 1. Skeletal Class III malocclusion was largely due to the overgrowth of mandible in man and the undergrowth of maxilla in woman. 2. The mandible was antero-inferiorly overgrown by large MP-HP angle and large gonial angle in orthognathic surgical cases with skeletal Class Iii malocclusion. And also, upper incisors were severely labioversioned, but on the other hand lower incisors were linguoversioned. 3. In female, lower-third facial height was characteristically shortened in comparison with middle-third facial height and also, lower facial throat angle was sgrall in male.
Dentistry ; Female ; Hand ; Humans ; Incisor ; Male ; Malocclusion* ; Mandible ; Maxilla ; Molar ; Orthodontics ; Orthognathic Surgery ; Pharynx ; Skeleton* ; Temporomandibular Joint

This study was performed, by Finite Element Method, to evaluate the stress distribution on the periodontal tissue according to activation of the various closing loops and to predict the pattern of movement of maxillary incisors. At the same time, bull loop, key-hole loop, T-loop, combination loop and asymmetrical T-loop which were used for retraction of maxillary incisors was analysed by Finite Element Method. The following results were obtained. 1. Horizontal force wits the greatest in bull loop, the followed by key-hole loop, combination loop, T-loop and initial tooth movement exhibited uncontrolled tipping. 2. Horizontal force in asymmetrical T-loop compared to other closing loops was remarkably decreased, and the intrusive force on the incisors occurred. 3. As torque was increased, the moment was increased as a linear increment. 4. As moment was increased, initial movement of tooth changed to root movement from uncontrolled tipping.
Incisor* ; Tooth ; Tooth Movement ; Torque

The purpose of this study was to evaluate racial differences in head posture and the influence of head posture to the craniofacial morphology. The sample group of this study was made up of 51 Korean males and 120 Scandinavian Caucasian males. From the comparison of the cranio-cervical angels and the variables of craniofacial morphology between them, the following results were obtained. 1. the cranio-cervical angle (NSL/OPT) was on average 9.28 degrees larger in Koreans. 2. The length of the anterior cranial base (N-S) was on average 4.66mm shorter in Koreans. 3. The length of the maxillary base (sp-pm and ss-pm) were on average 2.75mm and 4.65mm shorter in Koreans respectively, the anterior maxillary height (n-sp) was on average 2.60mm longer, the posterior dimension (s-pm) was found to be 2.06mm longer in Koreans, and the maxillary inclination (NSL/NL) was identical in both samples. 4. The mandibular body length (pg-tgo) and ramus height (ar-tgo) were identical in the two groups, but the gonial angle (ML/RL) was 3.22 degrees smaller and the mandibular plane inclination (NSL/ML) was 2.44 degrees larger in Koreans. 5. The maxillary prognathism (s-n-sp and s-n-ss) and the mandibular prognathism (s-n-ss) were identical in both samples. 6. The sagittal jaw relationship (ss-n-pg) was 1.44 degrees larger in the Koreans sample, but the vertical jaw relationship (NL/ML) was not significantly different. 7. The anterior facial height (n-gn) was 5.57mm longer in the Koreans sample. 8. The mandibular alveolar prognathism (CL/ML) was 5.71 defrees greater and the interincisal angle (ILs/ILi) was 3.08 degrees more acute in Koreans. Taken together these results, craniofacial morphology can be influenced by the head posture defined by cranio-cervical angulation.
Head* ; Humans ; Jaw ; Male ; Posture* ; Prognathism ; Skull Base

The purposes of this study were to evaluate and compare the frequency of ceramic bracket fracture, frequency of enamel fracture, bond fracture site, adhesive remnant index after mechanical and electrothermal debracketing, to evaluate effectiveness of high and low speed rotary instrument and ultrasonic instrument during residual adhesive remnants removal, and to measure resin film surface(percentage) using by image artalyser(Leco 300). Bond fracture site, bracket fracture, and enamel surface damage were examined by scanning electron microscope. The following results were obtained: 1. In the mechanical debracketing group, the bond failed predominantly at enamel-adhesive interface with the bulk of adhesive remaining on bracket base. 2. In the eletrothermal debracketing group, the bond failed predominantly at adhesive-bracket interface with the bulk of adhesive remaining on enamel surface. 3. The most effectiveness of residual resin removal was obtained by means of the resin polishing bur and the order of scratch formation was the precedure using tungsten carbide bur, ultrasonic scaler, sot-lex disc, and polishing bur. 4. The order of the resin film surface percentage was ultrasonic scaler, tungsten carbide bur, sot-lex disc, and resin polishing bur.
Adhesives ; Ceramics* ; Dental Enamel* ; Tungsten ; Ultrasonics

The purpose of this study was to identify the compensatory adaptation of dentoalveolar structure according to the various skeletal relation though the statistical correlation between the anteroposterior, vertical skeletal and dentoalveolar relation, For this study, the sample were consisted of 101 adult subjects (51male and 50 female, mean age; male 23.6 years, female 21.5 years) who had good occlusion with the range of normal overjet and overbite and acceptable Angle's class I molar relationship which had not been related orthodontically. The results were as follows : 1. Even though acceptable normal occlusion, the range of measurements which represent anteroposterior, vertical skeletal relation and dentoalveolar relation were very wide. 2. Upper and lower incisor axis were significantly correlated with anteroposterior skeletal relation, which means the more lingual inclination of upper anterior teeth and the more labial inclination of lower anterior teeth according to the more anterior position of mandible to the maxilla (p<0.01). 3. Upper and lower anterior alveolar bone height was statistically correlated with the lower anterior vertical skeletal height. 4. Upper and lower alveolar bone hight were not correlated with anteroposterior skeletal relation (p>0.05). 5. The correlation between the incisor axis and vertical skeletal was more closely related in upper anterior teeth than the lower anterior teeth. To summarize the above results, even though acceptable normal occlusion, skeletal and dentoalveolar relation was very widely ranged, and there were close relationship between the anteroposterior skeletal relation and the inclination of upper and lower anterior teeth and between the vertical skeletal relation and upper and lower anterior alveolar bone height. These finding can be concluded as compensatory adaptation to the different skeletal relationship
Adult ; Axis, Cervical Vertebra ; Female ; Humans ; Incisor ; Male ; Mandible ; Maxilla ; Molar ; Overbite ; Tooth*

Rapid palatal expansion(RPE) is a method of inducing the new bone formation in the palate by separation of the midpalatal suture, which can be done conveniently by placing heavy force across the maxillary dental arch. This experiment was undertaken to examine the histologic changes after RPE and during retention period. Four young adult dogs(a control dog, three experimental dogs) aged 4 to 6 months old were used for this experiment Expansion screw(Hyrax(R), Dentarum Inc.) was delevered to the palate and turned 180 degrees every morning and evening for 8 days, giving a total expansion of 72mm. A control dog was sacrified at the starting point of this study without any treatment and three experimental dogs were sacrified after RPE, 14-day retention, and 28-day retention in each. Thereafter, those samples were observed with hematoxylin-eosin(H-E) stain, ground section(Vrillanueva stain), alkaline phosphatase(ALP) stain, tartrate-resistant acid phosphatase(TRA) stain. The results were as followings: 1. After RPE, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts were flattenedinactive state and also, a little osteoid tissues was observed. Few multinucleated osteoclasts which had TRAPpositive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 2. After 14-day retention, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts which had ALP-positive activity in their cytoplasm were seen. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 3. After 28-day retention, collagen fiber bundles were arranged like those of control dog and osteoblasts which showed a lot of immature bone formation were cuboidal shape and exhibited ALP-positive activity in their cytoplasm. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. According to the above results, the new bone formation after rapid palatal expansion was examined after 14-day retention and significantly increased. after 28-day retention.
Animals ; Collagen ; Cytoplasm ; Dental Arch ; Dogs* ; Humans ; Infant ; Osteoblasts ; Osteoclasts ; Osteogenesis ; Palate ; Sutures* ; Young Adult*

An epidemiological investigation was carried out at Yongin, Kyungkido, South Korea to determine the prevalence of symptoms of temporomandibular disorders and parafunctional habits in adolescent aged 16, 17 and 18 years. 2,098 students(male 507, female 1,591) were randomly selected and investigated with the questionnaire. The results were obtained as follows. 1. The prevalence of symptoms of temporomandibular disorders was 80.9% total, 77.3% for male and 82.0% for female with significance between male and female(P<0.05). 2. The prevalence of symptoms of temporomandibular disorders was gradually increased according to increasing age with significant difference among ages(P<0.01) 3. The most frequent symptom in the temporomandibular disorders is pain on chewing(65.9), and then clicking(50.7%), pain on mouth opening(41.8%), and pain on TMJ(36.8%). 4. There was little corelationship between clenching habits and symptoms of temporomandibular disorders(r=0.166), and also between bruxing habit and those(r=0.057).
Adolescent ; Female ; Gyeonggi-do* ; Humans ; Korea* ; Male ; Mouth ; Prevalence* ; Surveys and Questionnaires ; Temporomandibular Joint Disorders*

This study was done to recognize the importance of errors in measurements of cephalometric radiograph and to find the anatomical structures those need special care to select as a reference points through the detection of the systematic errors and estimation of random errors. For this purose, 100 cephalometric radiographs were prepared by usual manner and 61 reference points, and 130 measurement variables were established. Measurement errors were detected and estimated by the comparison of the 25 randomly-selected samples for repeated measurements with the main sample. The following results were obtained: 1. In comparison of the repeated measurements, there were statistical significant differences in 24 variables which were 18.4% of 130 total variables. 2. The frequency of the difference in identification of the reference points between the repeated measurements was very high in the root apex of upper incisor(as), the most posterior wall of maxilla(tu), soft tissue nasion(n'), soft tissue frontal eminence(ft), and adl in airway. 3. After correction of reference points marking until the level of below 59,6 significance, the range of random errors were from 0.67 to 1.71 degree or mm. 4. The variable shown the largest random error was the intenncisal angle(ILs-lLi). 5. Measurement errors were mainly caused by the lack of precision in anatomic definitions and obscure radiographic image. From the above results, the author could find the high possibility of errors in cephalometric measurements and from this point, we should include error analysis in all the studies concerning measurments. In is essential to have a concept of error analysis not only for the investigator but also for a reader of other articles.
Activities of Daily Living ; Humans ; Research Personnel

This study was done to identify the changes of bite force and occlusal contact between before and after stabilization splint therapy. 16 female patients, accepted for orthodontic treatment at the Department of Orthodontics, College of Dentistry, Chosun University, were selected as the sample of this investigation. For comparisons, the samples of 16 were divided into just before stabilization splint, 1 month after stabilization splint, 2months after stabilization splint, and 3 months after stabilization splint and used the T-scan system to identify the bite force and occlusal contact changes for each group. Statistical analysis of the data was carried out ANOVA tests, and Turkey test using SPSS/PC(+). The results were as follows : 1. Bite force change from just before treatment to 1 month after stabilization splint therapy was statistical significantly decreased (P<0.05). 2. Bite force change from 1 to 3 months after stabilization splint therapy showed no statistical significance(p>0.05). 3. The changes of anterior occlusal contacts showed no statistical significance regardless of the wearing periods of stabilization splint (p>0.05). 4. The changes of posterior occlusal contacts from just before treatment to 1 month after stabilization splint therapy was statistical significantly decreased (p>0.05). 5. The changes of posterior occlusal contacts during 1 to 3 months after stabilization splint therapy showed no statistical significance (p>0.05). 6. Posterior teeth rather than anterior teeth were more influenced by the changes of the number of occlusal contacts. To sum up above results, we may respect to capturing and stabilizing centric relation position just 1 month after stabilization splint therapy.
Bite Force* ; Centric Relation ; Dentistry ; Female ; Humans ; Orthodontics ; Splints* ; Tooth ; Turkey