The comparison of landmark identification errors and reproducibility between conventional lateral cephalometric radiography and digital lateral cephalometric radiography / 대한치과교정학회지

The purpose of this study is to evaluate the reproducibility and errors in landmark identification of conventional lateral cephalometric radiography and digital lateral cephalometric radiography. Fifteen conventional lateral cephalometric radiographs and fifteen digital lateral cephalometric radiographs were selected in adults with no considerations on sex and craniofacial forms. Each landmark was identified and expressed as the coordinate (x, y). The landmarks were classified into 3 groups. The landmarks of the first identification was T1, identification after one week was T2, and identification after one month was T3. The mean and standard deviation of identification errors between replicates were calculated according to the x and y coordinates. The errors between first identification and second identification were expressed as T2-T1(x), T2-T1(y) and those between first identification and third identification were expressed as T3-T1(x), T2-T1(y). Each was divided into conventional lateral cephalometric radiography and digital lateral cephalometric radiography. The independent t-test was used for statistical analysis of identification errors for the evaluation of reproducibility. The results of this study were as follows; 1. Generally, the mean and standard deviation of landmark identification errors in digital lateral cephalometric radiography was smaller than those of conventional lateral cephalometric radiography. 2. Only a few landmarks showed statistically significant difference in identification error between conventional lateral cephalometric radiography and digital lateral cephalometric radiography. 3. The enhancement of image quality didn't guarantee decrease in landmark identification error and didn't affect tendency of landmark identification error.

Locus of control of surgical-orthodontic patient / 대한치과교정학회지

Surgical-orthodontic treatment is an increasingly more common dental procedure whose unique psycho-social or psychological feature has not been fairly quantified objectively. Since the treatment of a surgical-orthodontic (or orthodontic) patient is part science and part art, a subjective recognition of a patient about his or her own treatment may be more important than technical success during and after treatment. Therefore, the knowledge of the patient's underlying psychological status could be useful in the prediction of patient's response to surgical-orthodontic (or orthodontic) treatment. The purpose of this study was to investigate and evaluate the psychological difference between conventional orthodontic patient and surgical-orthodontic patient by using locus of control (LOC) examination. Locus of control scale has been proven to be extremely useful in the prediction of a variety of human behaviors. Two types of locus of control data (I-score, Internal locus of control score; E-score, External locus of control score) were obtained for 42 surgical-orthodontic patients and randomly selected 42 conventional orthodontic patients (as a control group) matched for age and gender. No statistically significant difference was observed in the scale of internal and external locus of control between the groups of surgical-orthodontic patients and conventional orthodontic patients. However, in the group of surgical-orthodontic patients, males showed lower E-score (external locus of control score, higher internal locus of control tendency) than females. The results of this study suggested that the psychological background of surgical-orthodontic patients, in contrast with that of cosmetic surgery patients, has a similar disposition with that of orthodontic patients.

Upper and lower second premolar extraction treatment case: Treatment strategy for Class III borderline cases / 대한치과교정학회지

When treating borderline cases which have mild crowding, non-extraction treatment may be considered firstly. But crowding may be reappeared by relapse and it may have problems in esthetics and stability. Secondarily four first premolar extraction treatment may be considered. But this may cause dish-in face by overretracting anterior teeth. In this cases, extraction of four second premolar is preferred because this resolves crowding without aggravating profile and has good stability after treatment. So we review cases treated by four second premolar extraction which show good treatment results and stability. The patients had good profile, Class I molar relationship, mild crowding and skeletal discrepancy and their growth had almost completed.

Clinical study on the anomalies of number and morphology in cleft lip and palate patients' teeth / 대한치과교정학회지

Cleft lip and/or palate (CLP) is one of the most common congenital craniofacial anomalies and occurs more frequently in Asian people. Dental abnormalities in number, size, shape, and eruption of teeth are frequently associated with CLP. The purposes of this study were to investigate the effects of CLP on number, size, shape and eruption of teeth and to provide basic clinical data for diagnosis and treatment of the CLP patients. With the orthodontic and cleft charts, diagnostic models, orthopantomograms and intraoral x-ray films from 241 CLP patients who visited Dept. of Orthodontics, Seoul National University Dental Hospital, we evaluated the frequency of congenital missing teeth, supernumerary teeth, impacted teeth, and microdontia. The results were as follows ; 1. Frequency of congenital missing was relatively high up to 56.8 %. Congenital missing occurred frequently in the maxillary lateral incisor and the maxillary second premolar. Among the CLP types, frequencies of congenital missing in cleft lip and palate group and cleft lip and alveolus group were higher than those of cleft lip group and cleft palate group. And bilateral cleft showed higher frequencies than unilateral ones. 2. Supernumerary tooth was shown in 11.2 % of CLP patients. It occurred frequently in the area between the maxillary lateral incisors and the maxillary canine. Among the CLP types, cleft lip group showed relatively most highest frequency. 3. Impaction was shown in 18.3 % of CLP patients. It occurred most frequently in the maxillary lateral incisor and the maxillary canine than other teeth. Among the CLP types, cleft lip group and cleft lip and palate group showed most highest frequencies. 4. Microdontia was shown in 15.8 % of CLP patients. It occurred the most frequently in the maxillary lateral incisors and maxillary canines. Among the CLP types, cleft lip and alveolus group and cleft lip and palate group showed relatively higher frequencies. There was no microdontia in cleft palate group.

The effect of the IGF-I treated gingival and periodontal ligament fibroblast on osteoblasts / 대한치과교정학회지

Insulin-like growth factor I (IGF-I) has the local tissue regulating actions. In bone, IGF-I increases the replication of osteoblastic lineage, probably preosteoblasts, and enhances osteoblastic collagen synthesis and matrix composition rates. The purpose of this study was to investigate the local regulatory effect of IGF-I on periodontium totally, both in an autocrine and paracrine manner. To examine the effect of IGF-I directly on osteoblast (OB) of test rats, and indirectly on OB via periodontal ligament fibroblast (PDLF), and the effect of gingival fibroblast (GF) on OB via cellular paracrine manner for the understanding of humoral action of adjacent tissue, GF and PDLF were obtained from male Sprague-Dawley rats of six to eight weeks of age. OB was obtained from frontal and parietal calvarial bone of Sprague-Dawley 21day-old-fetus. After each cell was incubated 24 hours, for collecting conditioned medium, different concentrations of IGF-I (1,10,100 ng/ml,1ml/well) was adding in the GF, PDLF cells, and the supernatant from these cultures was put into the primary OB culture with 1x104cell/ml/well. The experimental group was divided into six groups - control OB, IGF-I treated OB, OB culture with conditioned medium from PDLF, OB culture with conditioned medium from IGF-I treated PDLF, OB culture with conditioned medium from GF, OB culture with conditioned medium from IGF-I treated GF. After final IGF-I treatment, OB was incubated for 24 hours, and alkaline phosphatase activity assay, BMP expression, cell proliferation measurement using MTT assay, total protein measurement, collagen synthesis assay using western blot, and examination of bone nodule synthesis were done. Alkaline phosphatase expressions were increased in the group of PDLF-IGF-I supernatant treatment. Direct IGF-I treatment with concentrations of 100ng/ml showed increased viable cell number measured by MTT assay. And IGF-I treatment did not increase total protein amount. The entire experimental group showed BMP2, 4 expression in western blot, and there was no significant difference between control and experimental groups. These results suggested that supernatant from PDLF effects on increasing cellular activities of OB regardless of IGF-I, and at high concentration, IGF-I increases OB cell proliferation.

Long-term effects of chlorhexidine varnish treatment on microbial changes of dental plaque in orthodontic patients with fixed appliances / 대한치과교정학회지

The authors observed the long term effects of chlorhexidine varnish treatment on microbial of dental plaque in orthodontic patients with fixed appliances. The initial sample was 100 patients who were arranged to be treated with fixed orthodontic appliances. The final sample consisted of 21 patients who could be traced for 32 weeks after application of fixed orthodontic appliances. They were classified into the experimental group (12 patients) and the control group (9 patients). The experimental group was treated with chlorhexidine varnish once a week for 4 weeks before application of fixed orthodontic appliance. The control group was not treated with chlorhexidine varnish before application of fixed orthodontic appliance. The experimental group was treated once more after 20 weeks. The microbial changes of dental plaque were analysed by indirect immunofluorescence technique at pre-treatment 4, 8, 20, and 32 weeks. The result were as follows. 1. In the experimental group, streptococcus mutans was significantly suppressed during experimental period. (p<0.01) But, in the control group, streptococcus mutans was significantly increased after placement of fixed orthodontic appliances during experiment period. (p<0.05) 2. Streptococcus sanguis, streptococcus mitis, Actinomyces viscosus, and Actinomyces naeslundii did not show significant change between the experimental and the control group during experiment period.

Analysis of the primary and the permanent teeth dimension In Korean hemifacial microsomia patients / 대한치과교정학회지

Hemifacial microsomia (HFM) is the second most common craniofacial abnormalies. HFM represnted a spectrum of clinical findings such as hypoplasia of the mandibular ramus and condyle, confinement of maxilla growth, external and/or middle ear defects, involvement of some cranial suture, buccal soft tissue, facial nerve, and muscles in the affected side. HFM often showed progressive facial asymmetry and occlusal plane slanting to the affected side with growth. There were several reports about asymmetry of tooth maturation, hypodontia, delayed eruption, enamel hypoplasia in HFM. Since teeth develop in close association with size and morphology of the maxilla and the mandible, it is highly likely that dental changes will be present in HFM. So the purpose of this study was to investigate the differences of the primary and the permanent teeth dimensions in the maxillary and the mandibular dentition between the affected and the non-affected side of HFM. The sample of this study consisted of 34 unilateral HFM patients (18 males and 16 females, average age : 5 year 11 months old). The authors examined the mesiodistal and the faciolingual dimensions of the primary and the permanent teeth and performed statistical study by using paired t-test. The results were as follows : 1. The mesiodistal dimensions of the mandibular second primary molar and the mandibular first permanent molar in the affected side of HFM were significantly smaller than those of non-affected side. But there were no significant differences in the anterior teeth and the mandibular frist primary molar. It means that a gradient of severity from anterior teeth to posterior teeth was found in the mandibular dentition.. 2. Although there were no significant differences in the faciolingual dimensions of the primary and the permanent teeth in the maxillary and the mandibular dentition between the affected and non-affected side of HFM, there were general trend of compensatory increase in faciolingual dimension of the mandibular primary and the permanent teeth in the affected side. Therefore these results showed that HFM might affect on the abnormality of tooth dimension, especially the most posterior teeth, in the affected side of the mandible.

Submentovertex cephalometrics in Korean adults / 대한치과교정학회지

It is important that the orthodontist accurately assess the degree to which facial asymmetry contributes to a given malocclusion before treatment planning. P-A, submentovertex and verticosubmental view have been used in the assessment of facial asymmetry. Among them, submentovertex view is rarely used because it has low reproducibility and is short of normal data and proper analysis method. The purpose of this study was to develop a submentovertex cephalometrics and obtain normal data in Korean adults. The subjects consisted of 40 normal adults (male : 22, female : 18) without the experience of orthodontic treatment. We find the 2 angular and 9 linear measurements. Though submentovertex cephalomentrics has the limitation in comparing the absolute length between right and left, it is useful to examine the relationship of skeletal and dental midline, the shape and location of condyle head and the shape of mandibular body in submentovertex view. Therefore, if we understand the limitation of submentovertex cephalomentrics and use lateral, P-A submentovertex cephalomentrics together, we will measure the location and amount of skeletal disharmony more exactly.

A study for the development of the Korean orthodontic bracket / 대한치과교정학회지

The aim of this study was development of the Straight-Wire Appliance(SWA) suitable for the treatment of Korean. To accomplish the object of this study, Korean adult with normal occlusion were selected with following criteria: 1) no functional abnormality in the craniofacial area, 2) good dental arch form and posterior occlusal relationship, 3) Angle Class I occlusal relationship, 4) no experience of orthodontic, nor prosthodontic treatment, especially, no dental treatment on labial and buccal surfaces of teeth, 5) good facial profile. Impression were taken for upper and lower dental arches of the selected normal occlusion samples and the orthodontic dental stone models were fabricated. 5 well-trained orthodontists had examined the acquired dental stone models to select study samples which satisfy the Six keys to optimal occlusion of Andrews. 155 pairs of dental stone models (92 pairs of Male, 63 of Female) were finally selected. 3 dimensional digitization were performed with the Coordinate Measuring Machine(CMM, MPC802, WEGU-Messtechnik, Germany) and measuring of Angulation, Inclination, In-and-Out, Molar offset angle and Arch form were accomplished with a measuring software to achieve data for the development of SWA. Before the measurement, error study was performed on the 3 dimensional digitization with CMM, and the analysis of reliability of computerized measuring method adapted in this study and conventional manual method presented by Andrews was performed. Results of this study were as follows: 1. Equi-distance digitization with mesh size 0.25 mm, 0.5 mm and 1.0 mm were acceptable in 3 dimensional digitization of dental stone model with the CMM, and the digitization with 1.0 mm mesh size was recommendable in terms of efficiency. 2. Computerized measuring method with 3 dimensional digitization was more reliable than manual measuring method of Andrews. 3. Data were collected for the development of SWA suitable for the morphological characteristics of Korean with the computerized measuring method with 3 dimensional digitization.

The effect of chlorhexidine varnish application on the shear bond strength of orthodontic brackets / 대한치과교정학회지

The purpose of this study was to determine whether the application of chlorhexidine varnish affects the shear bond strength and failure pattern of orthodontic brackets or not. The experimental group consisted of 22 human premolars which extracted after chlorhexidine varnish application (4 times for 1 week interval) in vivo, and the control group consisted of 22 human premolars which extracted without any pre-treatment. After all teeth wee etched with 37% phosphoric acid gel, metal orthodontic brackets (Q-3002, RMO, USA) were bonded to each tooth using auto-polymerizing orthodontic resin (Ortho-One, Bisco, USA) with the same bonding procedure. The shear bond strength was measured with Instron universal testing machine (model 4466, Instron Ltd., England), and the failure pattern of each bracket was examined with Scanning Electron Microscope (SM 840A, JEOL, Japan). The data were analysed statistically with t-test. The results were as follows: 1. Application of chlorhexidine varnish had no significant effect on the shear bond strength of the orthodontic bracket. 2. There was no significant difference in the failure pattern of orthodontic bracket between the experimental group and the control group.

MRI study of temporomandibular joint disorder in orthodontic patients / 대한치과교정학회지

Magnetic resonance imaging(MRI) of the temporomandibular joint(TMJ) is very useful method to diagnose internal derangement of the TMJ because of its high specificity for identification of condyle-disc relationships. The purpose of this study was to evaluate the existence, incidence and severity of internal derangement of th TMJ by the MRI of patients who are suspected to have TMJ disorder. MRI sample was composed of 50 subjects(10 males, 40 females) and the mean age was 22.9 years. 43 subjects of the sample were found to have positive findings. 56% of the subjects with positive findings had ADD(anterior disc displacement) without reduction, and 65% had internal derangement of bilateral joints. Distributions in the types of malocclusion in patients with positive findings, the Angle's classification had shown : the largest 41.9% for Cl II (39.6 for Cl II div 1 and 2.3% for Cl II div 2), 37.2% for Cl III, and 2.3% for the nuidentified. 8.6% of the subjects with positive findings had facial asymmetry and 55.8% had openbite. We can conclude that the percentage of CI II is the highest in patients with internal derangement of the TMJ. Openbite or facial symmetry is considered to be uncompensated or compensated deformity which results from facial skeleton remodeling in the process of degenerative joint disease(DJD) due to TMJ degeneration. Therefore it is recommended to screen the patients with facial asymmetry or openbite by MRI before the beginning of orthodontic treatment. Differential diagnosis is essential because the tendency of relapse is high after the orthodontic treatment and continuous observation of TMJ is needed in patients with TMJ disorder.

The establishment of orthodontic web server multimedia database system for continuing education / 대한치과교정학회지

The Objective of this research was to construct the multimedia database system that was necessary for the education of the practitioners and the students. To establish this system, there were technical problems as follows: 1) The processing of the images, 2) The rapid processing of the information with the computer network, 3) The development of diagnosis tools, 4) The technique to establish the database system, 5)The link between the database system and the internet, and 6) The method to educate through many cases. The analysis for diagnosis and treatment planning were provided as two parts : model analysis and cephalometric analysis. As a model analysis, arch length discrepancy and Bolton tooth ratio were provided for the part of patient information. Cephalometric analyses were provided in the part of initial diagnosis. The Cephalometric analysis ver 2.0 and the PowerCeph pro 3.3.5 were used to show Tweed, Steiner and Jarabak analysis. In the main part, Kim's analysis and some measurements were added. In the post-treatment or retention part, we show the superimposition of the cephalometrics with which you can find the effectiveness of the various orthodontic treatment. The address of this home page is "http://damis.snu.ac.kr/orthodontics"

Regional load deflection rate of multiloop edgewise archwire / 대한치과교정학회지

This study was conducted in order to analyze the mechanical characteristics of multiloop edgewise archwire(MEAW). The purposes were 1) to compare load deflection rate(LDR) of MEAW with that of various other archwires in the individual interbracket span, 2)to compare the wire stiffness in the interbracket span with that in the multi-L-loop region (the span from distal border of the bracket of the lateral incisor to the mesial border of the buccal tube of second molar), and 3) to verify the experimental results with theoretically derived formula. The single L-loops five different horizontal lengths and multi-L-loops for the upper and lower arches were made out of .016 X .022 permachrome stainless steel wire. Straight segment of plain stainless steel, TMA and NiTi wire of the same dimension were prepared. The LDR was measured using Instron model 4466 with the load cell of 50N capacity at cross head speed of 1.0mm/min, and maximum deflection of 1.0mm. Five specimens were tested under each experimental condition. The wire stiffness number for each interbracket region and multi-L-loop region was calculated from the LDR and the interbracket spans. By dividing the theoretical model of multi-L-loop into 35 linear segments, the energy stored in each segment was obtained. Then the LDR and wire stiffness of single L-loop and multi-L-loop were calculated and compared. The findings were as follows : 1) The average LDR of MEAW in the individual interbracket region was 1/1.53 of that of the NiTi, 1/247 of TMA and 1/5.16 of the plain stainless steel wire. 2) The wire stiffness of MEAW in the multi-L-loop region was 1.53 times larger than that in the interbracket region, and the LDR was almost twice as large as that of NiTi in that region. 3) According to the theoretically derived equation, the wire stiffness of the single L-loop was lower than that of multi-L-loop. The results of this study suggest that MEAW has the unique mechanical property which could allow individual tooth movement and transmit elastic force effectively through the entire arch wire.

The study on the cleft lip and/or palate patients who visited Dept. of The study on the cleft lip and/or plate patients who visited Dept. of Orthodontics, Seoul National University Dental Hospital during last11 years(198 / 대한치과교정학회지

Cleft lip and/or palate is one of the most common congenital craniofacial anomalies. According to previous epidemiologic studies, incidence of cleft lip and/or palate has been increasing nowadays. However, there is no report about epidemiologic study of cleft lip and/or palate patients who visited dept. of orthodontics in Korea. So the purpose of this study was to provide the epidemiological characteristics and important basic clinical data for the diagnosis and the treatment of the cleft lip and/or palate patients. With the orthodontic and the charts, diagnostic models and X-ray films from 250 patients with cleft lip and/or palate who visited Dept. of Orthodontics, Seoul National University Dental Hospital during the last 11 years, the authors investigated patient`s visiting year, types of cleft, patient`s gender, and Angle`s classification of malocclusion, and surgery timing. 1. The number of cleft patients who visited Dept. of Orthodontics, SNUDH increased during 1988-1990and then it declined until 1992. From 1993 to 1996, it showed a stationary trend. After 1997 it showed an overwhelmingly increasing trend. 2. In the cleft type, the ratio of cleft lip : cleft lip and alveolus : cleft palate : cleft lip and palate was 7.6 : 19.2 : 9.6 : 63.6. In cleft position, unilateral clefts were more than bilateral ones (cleft lip 79 : 21, cleft lip and alveolus 77 : 23, cleft lip and palate 75.5:24.5). In cleft side, left clefts were more than right cleft (cleft lip 53.3 : 46.7, cleft lip and alveolus 59.5 : 40.5, cleft lip and palate 59.2 : 40.8). 3. In gender ratio, males were more than females in cleft lip (57.9 : 42.1), cleft lip and alveolus (68.8 : 31.2) and cleft lip and palate (76.1 : 23.9). But in cleft palate females were more than males as 41.7 : 58.3. 4. In the age groups, 7-12 year group was the most abundant as 52%, and then 0-6 year group (20.4%), 13-18 year group (17.2%), more than 18 year group (10.4%) were followed as descending order. 5. Most of the cleft lip repair surgeries were operated in 0-3 month (60.3%) and 4-6 month (17.9%). 6. The cleft palate repair surgeries were done in 1-2 year (31.7%), 0-1 year (25.6%), 2-3 year (12.1%), more than 5 year (11.6%) as descending order. 7. The lip scar revision surgeries were done before admission at elementary school 60%. (4-6 year (27.5%), 6-8 year (19.6%), more than 10 year (19.6%), 2-4 year (13.7%) as descending order) 8. The rhinoplasties were done before admission at elementary school in 51.7%. (0-2 year (7.1%), 2-4 year (14.3%), 4-6 year (21.4%), 6-8 year (14.3%)) 9. The pharyngeal flap were done at 6 Y (72.5 months) after birth on average and there was even distribution of surgery timing. 10. In relationship between Angle`s classification of malocclusion and cleft types, Class I was most abundant and Class III, Class II were followed as descending order in cleft lip group. But Class III was most abundant and Class I, Class II were followed as descending order in cleft lip and alveolus group, cleft plate group, and cleft lip and palate group. The percentage of frequency in Class III malocclusion was overwhelmingly higher in cleft lip and palate group than any other groups. 11. Because the frequency of Class III malocclusion was most prevalent in all age groups, anterior crossbite was the most common chief complaint of cleft patients.

Analysis of alveolar molding effects in infants with bilateral cleft lip and palate when treated with pre-surgical naso-alveolar molding appliance / 대한치과교정학회지

The goals of this study were 1) to present pre-surgical naso-alveolar molding(PNAM) appliance for bilateral cleft lip and palate treatment and 2) To evaluate the effects of the PNAM appliance on the alveolar molding of the premaxilla and the lateral segments. Subjects consisted of 8 bilateral cleft lip and palate infants (7 males and 1 female, mean age at first visit = 61.6 days after birth) who were treated with PNAM appliances in Department of Orthodontics, Seoul National University Dental Hospital. Average alveolar cleft gap between the premaxilla and lateral segment was 8.09+/- 5.03mm and average duration of alveolar molding treatment was 8.8+/-3.1weeks. These patients' models were obtained at initial visit (T0) and after alveolar molding (T1). 20 linear and 14 angular variables were measured by using photometry and digital caliper. All statistical analyses were performed by Microsoft Excel 97 program. Paired t-test was used to discriminate the effect of alveolar molding by PNAM appliance. 1. Closure of the alveolar cleft gap in bilateral cleft cases by molding therapy was completed successfully. 2. Alveolar molding inhibited outward growth of lateral segments and produced inward bending of lateral segments. 3. By bending the anterior part of the vomer, the premaxilla could be rotated and moved posteriorly via alveolar molding. Conclusion : This appliance can be applied to bilateral cleft lip and palate infants with satisfactory result before cheiloplasty.

Presurgical naso-alveolar molding appliance for unilateral cleft lip and palate / 대한치과교정학회지

The goals of this study were to present presurgical naso-alveolar molding (PNAM) appliance in unilateral cleft lip and palate treatment and to evaluate the effects of PNAM appliance on alveolar molding. Samples were consisted of 4 unilateral cleft lip and palate infants (3 males and 1 female, mean age=23.2 days after birth) who were treated with PNAM appliances in Department of Orthodontics, Seoul National University Dental Hospital. Average alveolar cleft gap between the greater and lesser segment was 8.27 mm and average duration of alveolar molding treatment was 9.7 weeks. These patients' models were obtained at initial visit (TI) and after successful alveolar molding (T2). Seven linear and five angular variables were measured by using photometry and digital caliper. All statistical analyses were performed by SPSS win ver. 7.5 program. Paired t-test was used to compare the mean values. 1. The posterior part of alveolar segments are the stable structures during alveolar molding treatment period in infants. 2. Forward growth of the greater segment may be hindered by the action of alveolar molding. 3. The closure of cleft gap during alveolar molding were usually due to inward and backward bending of the anterior part of the greater segment and outward bending of the whole lesser segment.

The effect of heat sterilization on the surface topography and the tensile properties in various nickel titanium wires including a Korean product / 대한치과교정학회지

The purpose of this study is to investigate the changes of mechanical properties and surface topography of various nickel titanium wires after heat sterilization for recycling with quantitative method. The materials used were four kinds of nickel titanium orthodontic wires including a Korean product. Experimental specimens were treated with two kinds of heat sterilization methods; dry heat (180degrees C, 60snin) and autoclave (121degrees C, 15-20psi, 30min). Mechanical properties were evaluated by tensile test with Instron 4466 (load cell capacity : 1000 kg, cross head speed : 5mm/min, grip distance : 40mm, in room temperature). Surface topography of various wires was compared with each other qualitatively by using scanning electron microscopy and quantitatively by using profilometer. The findings were analyzed statistically with student t-tests. The results were as follows; 1. Neither method of heat sterilization hod any effects on tensile properties of the nickel-titanium wires used in this experiment. 2. Before heat sterilization, the surface smoothness was highest in Optimalloy, followed by Align and Sentailoy, with NiTi showing the lowest smoothness value. 3. In surface topography, Align and Optimalloy were not influenced by heat sterilization. NiTi, on the other hand, had increased roughness after dry heat sterilization and Sentalloy showed the same tendency after each of the two heat sterilization procedures.

A study on the effect of the chincap by finite element analysis in juvenile skeletal Class III patients / 대한치과교정학회지

This study was conducted to investigate the changes in the structural parts of the craniofacial skeleton subsequent to chincap therapy in the juvenile skeletal Class Ill Patients. The subject consisted of 29 Korean children(14 males, 15 females) who had skeletal Class M malocclusion and were undergone chincap therapy from the beginning of the treatment (and an auxiThary upper removable appliance, if necessary). The control group was composed of 21 children(10 males, 11 females) with skeletal Class Ill malocclusion who had no orthodontic treatment. Cephalometric data at the mean age of 7 and 2 years later were analyized by finite element method, and compared between groups by independent group t-test(p<0.05). The results of the present study were as follows; 1. There were no significant changes in the cranial base, posterior face, upper anterior face, ramus, chin and soft tissues by the chincap therapy. 2. The mandibular body showed significant differences in the minimum extention ratio and the overall shape ratio. This means that the vertical direction of growth was retarded by the chincap therapy. 3. The major direction of the growth in the maxillary basal bone was significantly more horizontal in the experimental group, which suggests that the vertical growth of maxilla was inhibited. 4. There was statistical difference in the major direction of the growth of the anterior face between groups. This may be due to the significant difference in the major direction of growth of the lower anterior face, supposed to be resulted from the mandibular rotation and/or displacement by the chincap therapy. The change in the oral functional space seemed to be caused by the same reason. 5. From the standpoint of these results, the retardation of growth, the changes of the growth direction and the morphological changes could be accepted partly, but the major effect of the chincap seems to be the rotation and the displacement of the mandible.

A study on the extracellular matrix in the artificially created cleft lip wound healing of rabbit fetuses / 대한치과교정학회지

Adult wound healing is accompanied with inflammation and eventual scar formation, whereas fetal wounds heal rapidly by mesenchymal proliferation without significant inflammatory cell participation and with minimal or no scar formation. The cellular mechanisms underlying these differing forms of wound healing are unknown but the extracellular matrix, through its effects on cell function, may play a key role. Therefore the purpose of this study is to investigate the spatial and temporal deposition of several component of extracellular matrix, which are known to be involved with scar formation, in the artificially created cleft lip wound healing of fetuses. The author had undergone hysterotomy and created cleft lip-like defects on fetuses of New Zealand White Rabbit in mid-third trimester(24 days). Fetuses were divided into the repaired group, the unrepaired group and the sham-operated control group. At 1, 2, 3, 5, 7 days after procedure, fetuses were obtained by Caeserean section. After documenting the viability of fetuses, they were photographed to compare size and facial morphology and sectioned for histological examination by H & E stain and spatial and temporal deposition of collagen type I. III, IV, V and fibionectin, laminin by immunohistochemical method. The findings are summarized as follows: 1. There were lack of inflammation in the repaired and the unrepaired group during experimental periods. 2. The reepithelialization of the unrepaired group was slower than that of the repaired group. 3. Collagen I, III, V were found from post-op. third day. There were no difference of distribution in the control, the repaired and the unrepaired group. Collagen types I, III, V were present in all groups with restoration of the normal collagen pattern in the fetus. This implies that lack of scarring in fetal wounds is due to the difference of collagen organization pattern within wound and not simply lack of collagen formation. 4. Collagen IV was slightly increased at post-op. third day and decreased after post-op, fifth day. Eventually there were no differences in the control, the repaired and the unrepaired group. Laminin was found at post-op. fifth day and maintained staining density until post-op. seventh day. There were no differences in the control, the repaired and the unrepaired group. According to staining of laminin and collagen type IV in epithelial basement membrane, formation of epithelial basement membrane was not completed until reepithelialization was finished. 5. According to staining of laminin and collagen type IV, there were no increase of neovascularity in the repaired and the unrepaired group. 6. Fbbronectin was increased until post-op. third day at fibrin clot, wound base and margin and decreased after post-op. fifth day. Eventually, there were no differences in the control, the repaired and the unrepaired group, So it implies fibronectin plays a role as provisional matrix for fetal wound healing

The evaluation of sella turcica on the shape and volume in class III patients / 대한치과교정학회지

Sella turcica contains pituitary gland that has influence on craniofacial growth So, if the volume of sella turcica correlate to the function of pituitary gland, we can assume that the volume of sella turcica in skeletal Class III patients has some difference to that of normal occlusion group. The purpose of this study was to evaluate the difference of shape and volume of sella turcica between normal occlusion group and Class III patients. The shape of sella turcica was Classified by Inaba method and the volume of sella turcica was measured in lateral and P-A cephalograms by Di Chiro method. To find out the possibility of the volume of sella turcica as diagnostic aid to predict Class III growth pattern, the correlation coefficients between the volume of sella and cephalometric variables were calculated. The results were as follows. 1. The volume of sella turcica in Class III patients is larger than that of normal occlusion groups. 2. The volume of sella turcica in female was larger than that of male in Class III patients. 3. The volume of sella turcica has close correlation with APDL ANB, SNA, SNB, ODI, gonial angle, post. cranial base length. 4. Sella Index (volume of sella / ant. cranial base length) can be a more accurate indicator that represent Class III growth pattern than volume of sella itself. 5. The morphologic pattern of sella turcica had no significant difference between two groups.