• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.211-218
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• 2011

Purpose: Intentional replantation (IR) is a suitable treatment option when nonsurgical retreatment and periradicular surgery are unfeasible. For successful IR, fracture-free safe extraction is crucial step. Recently, a new extraction method of atraumatic safe extraction (ASE) for IR has been introduced. Patients and Methods: Ninety-six patients with the following conditions who underwent IR at the Department of Conservative Dentistry, Seoul National University Bundang Hospital, in 2010 were enrolled in this study: failed nonsurgical retreatment and periradicular surgery not recommended because of anatomical limitations or when rejected by the patient. Preoperative orthodontic extrusive force was applied for 2-3 weeks to increase mobility and periodontal ligament volume. A Physics Forceps was used for extraction and the success rate of ASE was assessed. Results: Ninety-six premolars and molars were treated by IR. The complete success rate (no crown and root fracture) was 93% (n = 89); the limited success rates because of partial root tip fracture and partial osteotomy were 2% (n = 2) and 5% (n = 5), respectively. The clinical and overall success rates of ASE were 95% and 100%, respectively; no failure was observed. Conclusions: ASE can be regarded as a reproducible, predictable method of extraction for IR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2360-2367
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• 2013

The purpose of this study was to improve the paramedics skills to manage advanced airway by comparing speed and success rate between endotracheal intubation and laryngeal mask airway(LMA) insertion in a moving ambulance. Sixty subjects were randomly recruited and samely divided into control group and experimental group. And they were asked to join a practical experiment using dummy model. Data analysis was done by SPSS WIN 14.0 Version. As a result of this research, in terms of difference in speed according to patient's intubation posture, the speed of control group was indicated to be good in sniffing position(t=-4.038, p<.001). There was no difference in speed between two groups in neutral position. In the neutral posture given the endotracheal intubation, tooth fracture occurred in 16 people(53.3%). There was no difference in success rate between two groups. As for a change in self-confidence before and after experiment, the post self-confidence was indicated to have been enhanced in both groups. In conclusion, it is effective to use LMA in the traumatic patient who is unable to receive endotracheal intubation in sniffing position. It is very important for the paramedics to receive the continuous training of the airway management skills.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.183-194
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• 1989

This is a report of 2-cases of mandibular prognathism corrected by Intraoral oblique splitting osteotomy of mandibular ramus. The Intraoral oblique splitting osteotomy is a modification of sagittal split osteotomy of ramus and it is documented by Yoshida, on 1985. By this method. authors obtained the following results. 1. The patients' esthetic, psychological and functional problems were dissolved by setback of mandibular prognathism. 2. The postoperative infection, splitted bone segments fracture, paresthesia of the face and T.M.J. dysfunction were not appeared. 3. Postoperative intermaxillary fixation was maintained for 8 weeks. The patients could open their mouths in normal range after a week of intermaxillary fixation removal. 4. The soft tissue changes of lower lip and chin were about 1:1 to the hard tissue changes. 5. During intermaxillary fixation period and postoperative orthodontic treatment, slight relapse was observed. Now, the patients are under postoperative orthodontic treatment.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.90-97
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• 2008

The purpose of this study was to evaluate the effect of passive or active application of primer and coat times of bond on the shear bond strength when a self-etching primer adhesive (Clearfil SE Bond) was applied to enamel surface. Crowns of sixteen human molars were selected. Buccal and lingual enamels of crowns were partially exposed and slabs of 1.2 mm thick were made. They were divided into one of four equal groups (n = 8). Group 1: passive application of Primer and 1 coat of Bond, Group 2: active application of Primer and 1 coat of Bond, Group 3: passive application of Primer and 2 coats of Bond, Group 4: active application of Primer and 2 coats of Bond. Clearfil AP-X was bonded to enamel suface of each group using Tygon tubes. The bonded specimens were subjected to microshear bond strength (uSBS) testing with a crosshead speed of 1 mm/min. The results of this study were as follows; 1. The uSBS of Group 1 was the lowest among groups and the uSBS of Group 4 was the highest. 2. There was not statistically significant interaction between enamel uSBS by application method of Primer and coat time of Bond (p > 0.05). 3. There was not statistically significant difference between enamel uSBS by passive and active application of Primer (p > 0.05). 4. There was statistically significant difference between enamel uSBS by one- and two-coat of Bond (p < 0.05).

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.605-611
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• 1995

The purpose of this study was to evaluate effects of time on shear bond strengths of a light-cured glass ionomer cement and chemically cured resin cement to enamel, and to observe the failure patterns of bracket bondings. Shear bond strength of a light-cured glass ionomer cement were compared with that of a resin cement. Metal brackets were bonded on the extracted human bicuspids. Specimens were subjected to a shear load(in an Instron machine) after storage at room temperature for 5 and 15 minutes; after storage in distilled water at $37^{\circ}C$ for 1 or 35 days. The deboned specimens were measured In respect of adhesive remnant index. The data were evaluated and tested by ANOVA, Duncan's multiple range test, and t-test, and those results were as follows. 1. The shear bond strength of light-cured glass ionomer cement is higher than that of resin cement at 5 and 15 minutes. 2. The shear bond strengths of both light-cured glass ionomer cement and resin cement increase with time. There was no significant difference in those of both 1 day group and 35 day group 3. Light-cured glass ionomer cement is suitable as orthodontic bracket adhesives

• The korean journal of orthodontics
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• v.41 no.1
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• pp.6-15
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• 2011

Objective: The aim of this study was to evaluate the biomechanical aspects of peri-implant bone upon root contact of orthodontic microimplant. Methods: Axisymmetric finite element modeling scheme was used to analyze the compressive strength of the orthodontic microimplant (Absoanchor SH1312-7, Dentos Inc., Daegu, Korea) placed into inter-radicular bone covered by 1 mm thick cortical bone, with its apical tip contacting adjacent root surface. A stepwise analysis technique was adopted to simulate the response of peri-implant bone. Areas of the bone that were subject to higher stresses than the maximum compressive strength (in case of cancellous bone) or threshold stress of 54.8MPa, which was assumed to impair the physiological remodeling of cortical bone, were removed from the FE mesh in a stepwise manner. For comparison, a control model was analyzed which simulated normal orthodontic force of 5 N at the head of the microimplant. Results: Stresses in cancellous bone were high enough to cause mechanical failure across its entire thickness. Stresses in cortical bone were more likely to cause resorptive bone remodeling than mechanical failure. The overloaded zone, initially located at the lower part of cortical plate, proliferated upward in a positive feedback mode, unaffected by stress redistribution, until the whole thickness was engaged. Conclusions: Stresses induced around a microimplant by root contact may lead to a irreversible loss of microimplant stability.

• Journal of Oral Medicine and Pain
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• v.37 no.4
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• pp.251-256
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• 2012

With today's heightened interest in quality of life, leisure and sports activities were popular in the general public. Accordingly, the incidence of oral and maxillofacial injury are also rising. Use of a mouth protector to prevent the trauma of the oral and maxillofacial region is growing in importance, and among the mouth protector the mouthguard is the most commonly used. Mouthguard has been suggested to protect injuries by (1) preventing tooth injuries by absorbing and deflecting blows to the teeth; (2) shielding the lips, tongue, and gingival tissues from laceration; (3) preventing opposing teeth from coming into violent contact; (4) providing the mandible with resilient support, which absorbs an impact that might fracture the unsupported angle or condyle of the mandible; (5) preventing neck and cerebral brain injuries. Although mouthguard is effective for prevention of oral and maxillofacial injury, it is not widespread to athletes or general public and they are lack of awareness about the importance of mouthguard. We present the types and materials of mouthguard, things to consider when mouthguard fabrication, and the usage. This should be helpful in awareness about the importance and popularization of mouthguard.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.4
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• pp.363-368
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• 2000

The purposes of the study was to examine changes in thickness and strength of the rat femur after administration of sodium fluoride in the drinking water. 48 female Sprague-Dawley rats were randomly divided into 4 groups, and they were supplied with 0(control), 1, 5 and 50 ppm of fluoride in the drinking water ad libitum for 6 weeks. Rats were killed and both sides of femur were dissected. Bone strength was measured as the stress of failure of femur at the middle point and femoral neck with Instron. Histologic slides were prepared from the femur shaft with routine processing of fixing, demineralizing, embedding and HE staining. Thickness and area of cortical bone and medullary cavity were measured by using Camera Lucida and Image Analyzer. All the collected data were analyzed with one-way ANOVA, Duncan's multiple range test for post-hoc tests and ANCOVA using the SAS 6.12 package at the level of 0.05. Bone strength increased significantly in the animals given 1 and 5 ppm of fluoride in the water, as compared to the control group. There were significant decreases of stress at fracture in 50 ppmF group compared to the 1 and 5 ppmF groups. The similar trends of bone strength at the femoral neck fracture test, but there were no statistical significances. Cortical bone thickness and area of the femur increased in the 1 and 5 ppmF groups compared to the control. However, the thickness of 50 ppmF group also decreased significantly as compared to 1 and 5 ppmF groups. On the other hand, medullary thickness and area increased in all fluoride groups than control group. All of the findings presented support the conclusion that, low fluoride dosage used in water fluoridation could increase the bone strength and might have preventive effect on femur fracture.

• Journal of dental hygiene science
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• v.14 no.4
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• pp.461-467
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• 2014

The objective of this study was to evaluate the impact of the Q-ray view, a novel optical device on reliability of assessing a tooth status by dental hygiene students in the training for dental hygiene process. Twenty patients were enrolled in this study. Oral examinations were conducted by both seventeen third-year dental hygiene students and a trained faculty member. Traditional visual inspection was performed in phase I and then re-examined with Q-ray view in phase II. Restoration codes and lesion codes for each tooth were recorded separately according to the predefined criteria. As a measure of reliability, percent agreement and Cohen's kappa were determined. Agreements for each intraoral regions and types of lesion and restoration were calculated. Paired t-test and Pearson chi-square test for two proportions were used to compare mean Cohen's kappa and percent agreement at each phase. For the lesion code, mean kappa values of phase II for intraoral regions were significantly greater than that of phase I (p=0.017). For the both of the lesion code and restoration code, percent agreements of phase II for each types of lesion and restoration were significantly greater than that of phase II (p<0.001 and p<0.001, respectively). Especially difference of percent agreements between phase I and II for incipient caries, caries and fracture were significant for the lesion code (p=0.046, p<0.001, and p=0.029, respectively) and for not restored or sealed, tooth-colored restoration were significant for the restoration code (p<0.001 and p=0.011, respectively). The reliability of assessing a tooth status was improved when the Q-ray view used in dental hygiene student with beginner level of expertise. Q-ray view can be a promising device for conducting and educating the dental hygiene process better.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.2
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• pp.225-234
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• 2018

The purpose of this study was to analyze the ratio and rate of apical closure when inducing root growth of necrotic immature permanent teeth using alternative triple antibiotics. 24 permanent teeth in the treatment group and 27 premolars in the control group were retrospectively studied using periapical radiographs for more than 300 days after the first visit. The difference in the growth rate between the two groups was statistically compared using the Mann-Whitney test at a significance level of 0.05. There were no statistically significant differences between the two groups in the first month and during months 1 - 3, 3 - 6, and 6 - 12. After 12 months, the cumulative rate of decrease in the apical foramen width in the treatment group was 50.59% and that in the control group was 71.82%, which revealed a significant difference between the two groups. There were significant differences in the rates of decrease in the apical foramen width after 3, 6 months, and later period in the treatment group, respectively. The cumulative rate of increase in the root dentin area presented no statistically significant differences between the treatment group and control group during the entire period of examination.