• The korean journal of orthodontics
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• v.39 no.3
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• pp.168-176
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• 2009

Objective: The purpose of this study was to evaluate how airway changes influence facial growth during puberty in Korean children. Methods: Thirty-six patients aged 9 to 11 (mean age: 10.7 years) were selected. Cephalograms and hand-wrist x-rays were taken at pre-treatment (T1) and post-treatment (T2). The sample was divided into narrow (5.2 - 8.6 mm, AW-Narrow), medium (8.9 - 11.5 mm, AW-Medium), and wide (11.7 - 16.0 mm, AW-Wide) groups according to the airway width at T1. Cephalometric measurements at T1, T2 and growth from T1 to T2 were compared between groups. Results: The degree of increase in airway size in each group was 4.55 mm, 3.84 mm and 1.94 mm in the AW-Narrow, AW-Medium, and AW-Wide groups, respectively. Moreover, the differences were statistically significant. The significant smallest posterior facial height was found in the AW-Narrow group at T1. For the growth values from T1 to T2, the AW-Narrow group showed significantly larger values of PFH/AFH, facial axis, ANS (T1 - T2), and Gn (T1 - T2) than the AW-Medium group. Conclusions: The compensational changes in the airway width and facial growth were found in the narrow group. Surgical approach of the airway to prevent unfavorable facial growth in these years of age should be carried out, but with careful deliberation because these problems may be improved naturally.

• The korean journal of orthodontics
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• v.32 no.5 s.94
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• pp.327-342
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• 2002

Soft tissue profile is a critical area of interest in the development of an orthodontic treatment and diagnosis. The purpose of this study was to determine the facial profile preference of diversified group and to investigate the relationship between most Preferred facial Profile and existing soft tissue reference lines. A survey instrument of constructed facial silhouettes was evaluated by 894 lay person. The silhouettes had varied nose, lips, chin and soft tissue subnasale point. Seven sets of facial type were computer-generated by an orthodontist to represent distinct facial types. The varied facial profiles were graded on the basis of most preferred to least preferred. Every facial profile were measured by soft tissue reference lines(Ricketts E-line, Burstone B-line) to observe the most preferred facial profile. The results as follows: 1. In reliability test, the childhood group showed lower value than other groups, which means that this group has no concern on facial profile preference. 2. It appears that sexual and age difference made no significant difference in selecting the profile 3. An agreement to least preferred facial profile was higher than an agreement to most preferred facial profile. 4. Coefficient of concordance (Kendall W) was higher in the twentieth group. It means that a profile preference of the twentieth is distinct. 5. A lip protrusion (to Ricketts E-line and Burstone B-line) of most preferred facial profile was similar to measurements of previous study that investigate skeletal and soft tissue of esthetic facial profile of young Korean. So these reference lines can be used valuably in clinics. 6. Profile of excessive lip protrusion or retrusion to E-line & B-line was least preferred. 7. Most preferred profile of all respondents group was straight profile. Profile that showing convex profile was not pre(erred and the least preferred profile was concave profile.

• The korean journal of orthodontics
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• v.32 no.5 s.94
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• pp.343-353
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• 2002

This study was designed to investigate the stress distribution of alveolar bone in case of on masse retraction with lingual K-loop archwire using the 3-dimensional photoelastic stress analysis followed by stress freezing process. Lingual K-loop archwire which had loop in 15mm height was used and activated by retraction force of 350gm per each side. The results were as follows 1. Central incisor : As the closer side to crown, the larger tensile stress was distributed at both mesial and labial surfaces and the larger compressive stress was distributed at distal surface. As the closer side to root apex, the larger compressive stress was distributed at lingual surface. The compressive stress was distributed at root apex. 2. Lateral incisor : The tensile stress was distributed at the coronal side of mesial surface. The compressive stress was distributed at distal surface. As the closer side to crown, the larger tensile stress was distributed at labial surface. The tensile stress was distributed at coronal side and the compressive stress was distributed at apical side of lingual surface. The compressive stress was distributed at root apex. 3. Canine The tensile stress was distributed at coronal side and the compressive stress was distributed at apical side of mesial surface. The tensile stress was distributed at distal surface. As the closer side to crown, the larger tensile stress was distributed at both mesial and distal surfaces. The compressive stress was distributed at root apex. 4. Second premolar : The tensile stress was distributed at mesial surface. The compressive stress was distributed at coronal side and the tensile stress was distributed at apical side of distal surface. The compressive stress was distributed at coronal side of buccal surface. As the closer side to crown, the larger tensile stress was distributed at lingual surface. The compressive stress was distributed at root apex. 5. First molar . As the closer side to crown, the larger tensile stress was distributed at both mesial and distal surfaces. No stress was distributed at buccal surface and palatal root apex. As the closer side to crown, the larger tensile stress was distributed at both lingual surfaces. The compressive stress was distributed a4 buccal root apexes. 6. Second molar The compressive stress was distributed at all root apexes. As the closer side to crown, the larger compressive stress was distributed at both mesial and lingual surfaces, and the larger tensile stress at both distal and buccal surfaces. Transverse bowing effect was observed in on-masse retraction with lingual K-loop archwire, however vertical towing effect was not. Rather, reverse vortical bowing effect was developed.

• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.413-421
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• 2000

The purpose of this study was to observe the effects of pregnancy on the experimental tooth movement and alveolar bone turnover process of Sprague-Dawley female rat. Sixty rats were divided into pregnant-tooth movement group(P-Tm), normal-tooth movement group(N-Tm) and normal group(N). Maxillary first molar appliances were inserted bilaterally and activated to 40grams. To measure the amount of tooth movement, x-ray was taken 2 times after appliance insertion and before sacrifice. Animals were sacrificed at 1,3,7,14 days(N=5). Just after sacrifice, alveolar bones were collected and frozen immediately for biochemical analysis. Tooth movement was assessed cephalometrically and tartrate-resistant acid(TRAP) and alkaline phosphatase (ALP) activities were measured in extracts of paradental alveolar bone. The results were as follows: 1. The amount of tooth movement in P-Tm group was greater than that of N-Tm group(p<0.01). 2. Alveolar bone ALP of normal tooth movement group was not significantly different from the control, TRAP was significantly different from the control(p<0.01). In normal tooth movement group, alveolar bone ALP was increased gradually and peak(day 7) fell off significantly at day 14(p<0.05). The Peak of alveolar bone TRAP(day 7) fell off slightly, sustained day 14(p<0.01). 3. Alveolar bone ALP and TRAP of pregnant tooth movement group were not significantly different from that of normal tooth movement group. In pregnant tooth movement group, alveolar bone ALP was increased at day 3(p<0.01) and fell off significantly at day 7-14, alveolar bone TRAP were increased at day 3 and sustained day 14. 4. The peak of alveolar bone phosphatases in pregnant tooth movement group(day3) preceded the peak in normal tooth movement group(day7) (p<0.01). According to the above results, we suggested that bone resorption activity was increased in alveolar bone of pregnant rat, and the degree of tooth movement in pregnancy may be greater than that of normal group because of high bone turnover of alveolar bone in pregnant rat.

• The korean journal of orthodontics
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• v.27 no.1
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• pp.157-171
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• 1997

This study was conducted to see the effect of TiN ion-plating on the bond strength of orthodontic bracket. Three stainless-steel brackets with different base types were chosen; when TiN ion-plated brackets and non iorrplated brackets were bonded to the teeth, initial and long-term bond strength were measured, The observations oi bonding surface and failure sites through the scanning electron microscope were analysed and compared. The summary of this study was as follows; ${\cdot}$ When TiN ion-plating was not applied, the Micro-Loc type was the highest in bond strength atter 24 hours as $5.89{\pm}1.77$ MPa, followed by $4,27{\pm}1.12MPa$ for Foil Mesh type and $2.64{\pm}0.58MPa$ for Undercut type(P<0.05). ${\cdot}$ Under TiN ion-plating, the bond strength after 24 hours showed: Micro-Loc type $-6.26{\pm}1.51MPa$, Foil Mesh type $-7.45{\pm}2.01MPa$, Undercut type $-2.93{\pm}0.84MPa$. Unlike in the case of non ion-plating, Foil Mesh type showed a higher strength than Micro-Loc type, with Undercut type still showing the lowest bond strength(P<0.05). The bond strength, after 24 hours, increased in case of ion-plated in all 3 types, but a significant increase was shown only in Foil Mesh type(P<0.001). ${\cdot}$ Under a long-term immersion, regardless of ion or non ion-plating, bond strength in general increased over the initial bond strength(one day), with more stability. ${\cdot}$ Through scanning electron microscopic observation of bonding surface, it was found that, regardless of the bracket base type or the application of ion-plating, the resin was thoroughly spreaded into bracket base to form a solid bonding surface between the bracket and the tooth. This was also true in case of a long-term immersion. ${\cdot}$ The scanning electron microscopic observation of failure sites revealed diverse failure patterns.

• The korean journal of orthodontics
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• v.27 no.1
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• pp.141-155
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• 1997

The purpose of this study was to evaluate the effectiveness of the Nd:YAG laser and the Er:YAAG laser on etching enamel for direct bonding of orthodontic bracket. The advantages of laser etching rather than conventional acid etching are to reduce the subsurface demineralization rate, to inhibit the spillage of acid onto uninvolved ""its of enamel, and to save the clinical manipulation time involving drying, trashing and drying again. 189 freshly extracted human premolars were prepared for this research. 165 out of them were divided into 11 groups of 15 teeth. One group was acid etching and the rest groups were irradiated with Nd:YAG laser by four different energy levels(100mj 10pps, 100mj 20pps, 150mj 20pps, 200mj 20pps) and with Er:YAG laser by six different energy levels(60mj 5pps, 60mj 10pps, 100mj 10pps. 200mj 10pps, 200mj l5pps, 400mj 10pps). Shear bond strength was tested with Instron after 24 hours, one week, and three weeks. Twenty-four out of 189 teeth were divided into twelve groups untreated control, acid etching, and ten laser irradiation subgroups. And the ultrastructural enamel surfaces of each group were observed with scanning electron microscope. The results were as follows; 1. The means and the standard deviations of shear bond strength of Nd:YAG and Er:YAU laser irradiation by different energy levels were obtained. 2. Shear bond strengths of Er:YAG laser irradiation groups were higher than those of Nd:YAG laser irradiation groups at the identical energy level. 3. Maximum bond strengths was achieved at the energy of I50mj, 20pps in Nd:YAG laser irradiation groups or 60mj, 10pps in Er:YAG laser irradiation groups. 4. It was acceptible for direct bonding to irradiate lb0mj 20pps with Nd:YAG laser or to irradiate 60mj 10pps with Er:YAG laser considering the results of shear bond strength tests and SEM obsesvation.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.243-256
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• 2018

The purpose of this study was to investigate the effects of the anodization and cyclic calcification treatment on the surface characteristic and bioactivity of the titanium thin sheet in order to obtain basic data for the production of bioactive titanium membrane. A $30{\times}20{\times}0.08mm$ titanium sheets were prepared, and then they were pickled for 10 seconds in the solution which was mixed with $HNO_3:HF:H_2O$ in a ratio of 12: 7: 81. The $TiO_2$ nanotube layer was formed to increase the specific surface area of the titanium, and then the cyclic calcification treatment was performed to induce precipitation of hydroxiapatite by improvement of the bioactivity. The corrosion resistance test, wettability test and immersion test in simulated body solution were conducted to investigate the effect of these surface treatments. The nanotubes formed by the anodization treatment have a dense structure in which small diameter tubes are formed between relatively large diameter tubes, and their inside was hollow and the outer walls were coupled to each other. The hydroxyapatite precipitates were well combined on the nanotubes by the penetration into the nanotube layer by successive cyclic calcification treatment, and the precipitation of hydroxyapatite tended to increase proportionally after immersion in simulated body solution as the number of cycles increased. In conclusion, it was confirmed that induction of precipitation of hydroxyapatite by cyclic calcification treatment after forming the nanotube $TiO_2$ nanotube layer on the surface of the titanium membrane can contribute to improvement of bioactivity.

• Journal of Technologic Dentistry
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• v.17 no.1
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• pp.41-57
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• 1995

This study was conducted to collect and analyze previous information in order to manage efficience, improve experience effect and promote employment rate. The questionnaire interview with 27 chief of dental Laboratory refered clinical experience in technology department about clinical experience in 14 Jumior colleges were also investigated. The results were summarried as follows : The portion of age of 35-39 among chief of dental Laboratory was 40.7% which was the highest, that of male was 96.3%, that of junior college graduate was 97.5%, that of 10years experience was 92.6% and that of ceramic technician was 85.2%, 63.0% dental laboratory for clinical experience was a bore space of 30pyong. Aspect of dental laboratory management, manufacturing all part of prosthetic restoration was 29.6%, othodontic appliance and ceramic restoration was 7.4%, 3.8%, each. The percentage of 40.7 was having connection with 30-3a dental clinics and referring case per day was 10-19 cases(40.7%), manufacturing time of referred prosthetic restoration was 3-4 days(77.8%), places preparing seminar room for education was 29.6%, above a place of 40pyong was 11.1% 30-34 pyong and 35-39 pyong was 7.4% each. During training of 2 years education course student, 18.5% was rack of thorough occupational career. While 44.4% will want the more salary among 3years education course student, 74.1% will expect the more dental techmicians would engaged in their field, 51.9% will hope improve of their theory and practice, 29.6% be expected better skill and 14.8% be expected better theory. Attitude of clinical experience places was distributed by 59.3% of offering only experience chance, 25.9% of wasting time and 29.0% of annoying. The big emphasis of climical experience was thorough occupational career(44.4%). The clinical experience places of our college were selected after direct visiting, so their condition of management was not that bad but most of dental laboratory were poor in management state and working environment. Therefore it is difficult to choose appropriate places and dental Laboratory are also limited manpower and time as suppliers. So that it recommended to induce flexible management of experience period by interval and rotation of experience places among college and to applicate intern-system for employment ant industry-college cooperation aspect.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.9 no.2
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• pp.122-126
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• 2013

Cerebral palsy is one of the primary handicapping conditions of childhood. The prevalence of malocclusions in patients with cerebral palsy is approximately twice than in general population. Even though these high rates of malocclusions, most clinicians may feel uncomfortable about treating such problems to reduce inclination of anterior teeth because to reduce of protrusion makes to decrease risk of trauma. This is the case report about mitigation of maxillary anterior teeth protrusion in patient with cerebral palsy. A 14 year old boy who had cerebral palsy visited our dental hospital. He had severe protrusive maxillary anterior teeth and narrow arch form. He was experienced at using Castillo morales appliance in early childhood. He had mild mental retardation and was able to learn simple skills. He and his parents had willing to improve his dental problems. A gentle impression taking on maxilla was done. Removable appliance was made including median screw and labial bow. We provide a period of adaption for 3 weeks. After of anterior teeth through activation of labial bow was done once a month by dentist. The treatment carried out for 10 months and we could observe reduced labial inclination of maxillary right central incisor and more wide arch form. Hawley type retainer was set at maxilla for retention. In conclusion, accompanying careful case selection and treatment, patient with cerebral palsy can be treated and should not be ignored their orthodontic needs.

• Journal of Korean society of Dental Hygiene
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• v.17 no.5
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• pp.747-755
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• 2017

Objectives: The purpose of study is to investigate periodontal disease-related recognition and oral health-related behavior in orthodontic patients with fixed appliance. Methods: A self-reported questionnaire was completed by 286 orthodontic patients with fixed appliance in Gwangju, Jeonnam from September 1 to September 27, 2016. The questionnaire consisted of general characteristics (3 items), orthodontic related characteristics (3 items), knowledge of periodontal disease (3 items), and oral health-related behavior (4 items). The data were analyzed by frequency analysis, percentage and chi-square analysis using SPSS 21.0 program. Results: 62.8% had experiences of dental treatment and 67.5% had intention of involvement on incremental care program in orthodontic treatment periods. Accuracy rate of cause about periodontal disease was high in female and case of acquiring information experiences on periodontal disease (p<0.05). 67.2% performed correct toothbrushing for the management of periodontal disease in the experiences of acquiring information on periodontal disease in orthodontic treatment periods (p<0.05). The proportions of using interdental toothbrush and mouth rinsing solutions were high among those over 20 years old and students in the subjects (p<0.05). Conclusions:The accuracy rate were high in the answers about cause and management of periodontal disease in case of acquiring information experiences on periodontal disease in orthodontic treatment periods. Therefore, there is a need to further development and implementation of dental hygiene intervention program for periodontal disease care with fixed orthodontic appliances in that regard.