• The Journal of Korean Academy of Prosthodontics
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• v.36 no.6
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• pp.878-887
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• 1998

Although attachments have been utilized for a retainer of removable prostheses during several decades, there is little information on the force distribution by the attachments. This study was undertaken to evaluate the stress patterns developed by partial dentures employing rigid attachments on the supporting structures. Four types of the mandibular removable partial dentures were designed depending upon the position of the rigid attachment and the existency of lingual bracing. Under 100N of vertical and 25N of lateral loads on the 1st and 2nd lower molar of partial denture, stress distribution patterns and displacement were analysed with three dimensional finite element method by ANSYS version 5.3. 1. The highest stresses were concentrated on the distal alveolar crest of posterior abutment and the second stresses on the apical region of posterior abutment in the models. 2. The greatest displacement were shown on the distal alveolar crest of posterior abutment and the second displacement on the distal alveolar crest of anterior abutment in the models. 3. There was little difference between the models with intraoral attachment and those with extracoronal attachment. 4. There was little difference between the models with and without the lingual bracing.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.4
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• pp.312-321
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• 2007

Purpose: Distraction osteogenesis has been applied to the maxillofacial implantology and good experimental and clinical results have been reported. However, histologic studies of implants placement on distraction osteogenesis of atrophic alveolar ridges are scarce. In this study, we compare the bone formation between in the transport part and in the distraction part by histomorphometric analysis. Materials & methods: Three adult beagle dogs were served as experimental subjects. The 2 premolars and 1st molar were extracted on the Lt. side of mandible in each beagle dog. After one month later, osteotomy was performed and distraction device was adapted. Distraction was performed with gradual incremental separation of two bone pieces at a rate of 1.0mm per day for 5 days. During consolidation phase, new bone was formed in the distraction zone between the separated bone pieces. 5 weeks after distraction phase, 3 implants were placed in each beagle dog. The implants were inserted through transport part and distraction part and inferior basal bone. The animals were sacrificed at 2 weeks, 4 weeks, and 12 weeks after implant placement. BIC and BA of implants on distraction part and transport part were measured histomorphometrically. Results: BIC, BA increased after implant placement as time goes by passes and new bone formation was slightly higher in transport part than in distraction part at 2 weeks, 4 weeks after implant placement. At 12 weeks after implant placement, BIC, BA of were 74%, 61% in transport part and 77%, 59% in distraction part, therefore there were no difference in BIC and BA between transport part and distraction part at 12 weeks after implant placement.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.4
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• pp.275-282
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• 1992

Maxillofacial war injures is specific representative of severe hard and soft tissue defect. This type of injuries were different from the trauma because it may be fatal. The purpose of this study was to evaluate the injury type base on the retrograde medical record in the 104 patients from Feb. 1991 to Aug. 1992 in Korea Veterans Hospital. The obtained results were as follows. 1. Among 104 cases, 51 cases(49.0%) were classified as mandibular defects only, and 53 cases (51.0%) were classified as maxillary with mandibular defect (combined). 2. The etiologic factors of injury were gunshot, artillery and grenade or shell: 33 cases, 14cases, and 10 cases respectively in Korea War, 19 cases, 5 cases, and 8 cases respectively in Vietnam War. 3. In 57 cases of mandibular partial defect, the angle area showed the highest frequencies, 18 cases(31.6%). 4. In 42 cases of mandibular segmental defect, the area between the 1st molar and the ascending ramus showed the highest frequencies. 17 cases(40.4%), and almost all cases were unilateral defect (40 cases, 95.0%) 5. Reconstruction method performed for segmental mandibular defect were wire or plate(15 cases, 35.7%) and soft tissue closure only(12 cases, 28.7%), respectively.

• The korean journal of orthodontics
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• v.20 no.2
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• pp.247-266
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• 1990

The alveolar bone remodeling is essential in tooth movement by orthodontic forces. The collagen and chondroitin sulfate are acting as an important roles in bone remodeling. This study was performed to measure out the quantity of the collagen and chondroitin sulfate in the alveolar bone of rats applied by experimental orthodontic forces. The 150 Sprague-Dawley male rats were divided into the $PGE_2$ treated group, indomethacin treated group and the normal group. A 80gm force rubber band was used as a orthodontic appliance between upper incisors and right upper 1st molar, and left side of experimental rats with no appliance was regarded as a control side. The samples of alveolar bones were obtained from pressure and tension sites in all three groups. respectively, and in control sides, too. The results were as follows. 1. The change in total collagen remains stable in both pressure and tension sites of all three groups, compared with control side by the time consuming. 2. The change in soluble collagen showed the most highest level in tension site, lowest level in pressure site of $PGE_2$ treated group in 5th. experimental day. 3. The change in chondroitin sulfate showed the most highest level in pressure site, lowest level in tension site of $PGE_2$ treated group in 5th. experimental day. 4. In indomethacin treated group, the change of soluble collagen and chondroitin sulfate showed small range of variance compared with $PGE_2$ treated and normal group.

• Journal of Periodontal and Implant Science
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• v.31 no.2
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• pp.317-332
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• 2001

The purpose of this study was to investigate effects of the natural coral(NC) and the hydroxyapatite/calcium sulfate hemihydrate(HA/CS) on an early stages of wound healing in the rat periodontal fenestration defects. In this experiment, twelve male rats(Mean : 520g in BW) aged 8 to 9 months were used. Experimental periodontal fenestration defects were surgically created with tapered fissure bur at the buccal surface of the left mandibular 1st, 2nd molars. The buccal aspects of molar roots were carefully denuded of their periodontal ligament through a bony window created in the left mandibles of rats under general anesthesia. Each experimental periodontal fenestration defect was grafted with natural coral and HA/CS, randomly. An area without bone graft was assigned for negative control group. At 10,35 days, rats were serially sacrificed via intracardiac perfusion with 2.5% glutaraldehyde and specimens were processed with Hematoxylin-Eosin stain for light microscopic evaluation. The results of this study were as follows : 1. The defect areas were filled with dense connective tissues at 10 days in control group. But in the test(NC, HA/CS)groups, the connective tissues around graft materials were formed more loosely and the response of inflammation by graft materials itself was not found. 2. The defect areas were filled with new osteoid tissues and new cementum was not formed on the cut root surface at 35 days in the control group. 3. New osteoid tissue formation was more prominent at 35 days in control than test groups. 4. The NC and HA/CS particles were encapsulated by loose connective tissues at 10 days and by dense connective tissues at 35 days, respectively. 5. In the test groups, resorption of graft particles was not found through the experimental time. From the above results, natural coral and hydroxyapatite/calcium sulfate hemihydrate may be biocompatible and osteoconductive and have a weak adverse reaction to the periodontal tissues.

• The korean journal of orthodontics
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• v.47 no.6
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• pp.375-383
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• 2017

Objective: The purpose of this study was to evaluate the dental and skeletal effects of the modified C-palatal plate (MCPP) for total arch distalization in adult patients with Class II malocclusion and compare the findings with those of cervical pull headgear. Methods: The study sample consisted of the lateral cephalograms of 44 adult patients with Class II Division 1 malocclusion, including 22 who received treatment with MCPP (age, $24.7{\pm}7.7years$) and 22 who received treatment with cervical pull headgear (age, $23.0{\pm}7.7years$). Pre- (T1) and post-treatment (T2) cephalograms were analyzed for 24 linear and angular measurements. Multivariate analysis of variance was performed to evaluate the changes after treatment in each group and differences in treatment effects between the two groups. Results: The mean amount of distalization at the crown and root levels of the maxillary first molar and the amount of distal tipping was 4.2 mm, 3.5 mm, and $3.9^{\circ}$ in the MCPP group, and 2.3 mm, 0.6 mm, and $8.6^{\circ}$ in the headgear group, respectively. In addition, intrusion by 2.5 mm was observed in the MCPP group. In both groups, the distal movement of the upper lip and the increase in the nasolabial angle were statistically significant (p < 0.001). However, none of the skeletal and soft tissue variables exhibited significant differences between the two groups. Conclusions: The results of this study suggest that MCPP is an effective treatment modality for total arch distalization in adults.

• Korean Journal of Veterinary Research
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• v.50 no.4
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• pp.303-310
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• 2010

Demand on specialized feline dentistry has increased over the years, partly due to growing feline population in Korea. Despite the notable increase in the population, not much researches has been conducted on oral disease for stray cats. Thus this research was conducted on 81 adult stray cats from Gwangju in Korea (42 males and 39 females) with average weight of 3.4 kg and also focused on occurrence of periodontal disease (plaque and calculus), feline odontoclastic resorptive lesion (FORL), stomatitis and tooth anomaly. Formation of dental plaque and calculus were abundant on maxilla than mandible, especially distributed much on 4th premolar teeth and 1st molar teeth. After thorough examination of oral cavity, 33 stray cats (40.7%) were found to have oral disease. Eighteen stray cats (22.2%) had tooth fracture which was evident on cuspid and missing teeth were present on 2nd premolar tooth of maxilla and 2nd incisor of mandible amongst 20 stray cats (24.7%). FORL was present on cuspids and 2nd premolar tooth of maxilla among 10 stray cats (12.3%). Stomatitis was involved with FORL, missing tooth, and tooth fracture. Therefore, it was determined that stomatitis, FORL, and periodontal disease were closely associated.

• International Journal of Oral Biology
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• v.36 no.2
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• pp.51-57
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• 2011

Runx2 and Osterix, the transcription factors for osteoblast differentiation, are known as fundamental factors to regulate the development of calcified tissues. However, the biological functions of these factors in the development of the periodontal tissues remain unclear. In this study, we investigated the distribution of Runx2 and Osterix during periodontal tissue development of the mice. Mandibles from 14-day-old mice were prepared for paraffin section. Serial sections of the mandible containing $1^{st}$ molar tooth germs were obtained as a thickness of $7\;{\mu}m$. Some sections were stained with hematoxylin and eosin. Others were used for immunohistochemistry for PCNA, Runx2, and Osterix. Epithelial cells in growing end of Hertwig's epithelial root sheath (HERS) and mesenchymal cells adjacent to the growing end of HERS expressed PCNA. Undifferentiated mesenchymal cells and hard tissue forming cells like cementoblasts and osteoblasts in early stage of differentiation expressed Runx2. Fully differentiated cementoblasts and osteoblasts secreting matrix proteins expressed Osterix. However, the cells terminated the matrix formation did not express Osterix. Periodontal ligament cells expressed Runx2 and Osterix. Pulp cells expressed Runx2 only. These results suggest that Runx2 and Osterix might regulate the differentiation of cementoblasts in the same manner as osteoblasts. Runx2 might participate in the process of cementoblast differentiation in early stage, whether Osterix might regulate the maturation and matrix synthesis of the cells.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.113-119
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• 2009

The purpose of this study was to compare the tensile bond strength of several self-adhesive resin cements bonded to dentin surfaces with different wet conditions. Three self-adhesive resin cements: Rely-X Unicem (3M ESPE, St. Paul, MN. USA). Embrace Wetbond (Pulpdent. Oakland. MA. USA). Maxcem (Kerr. Orange. CA. USA) were used. Extracted sixty human molars were used. Each self-adhesive resin cement was adhered to the dentin specimens (two rectangular sticks from each molar) in different wet conditions. Tensile bond strength were measured using universal testing machine (EZ Test. Shimadzu corporation. Kyoto. Japan) at a crosshead speed of 1.0mm/min. After the testing. bonding failures of specimens were observed by Operative microscope (OPMI pro, Carl Zeiss. Oberkochen, Germany). T-test was used to evaluate the effect of dentin surface wetness. One-way ANOVA test was used to evaluate the tensile bond strength of self-adhesive resin cements in the same condition. Scheffe's test was used for statistical analyzing at the 95% level of confidence. The result showed that wetness of dentin surface didn't affect tensile bond strength of self-adhesive resin cements and Maxcem showed the lowest tensile bond strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.4
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• pp.296-305
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• 2013

For the purpose of evaluating the prevalence of malocclusion and self-esteem in adolescents, 1,380 middle-school students in the Yangsan area were surveyed by oral examination and questionnaires and the obtained results were as follows: The distribution of 1st molar occlusion by Angle's classification was 69.0, 19.4, 10.6% for Class I, II and III respectively. In the horizontal relationship, the prevalence of normal overjet and crossbite was 86.9% and 5.6% respectively whereas larger and extremely larger overjet was found in 6.6% and 0.8%. In the vertical relationship of anterior teeth, normal, deep overbite and openbite was shown in 94.1%, 4.7%, and 1.2%. For the midline discrepancy, the distribution of groups with 0~1 mm, 2~4 mm and over 5 mm was 98.2%, 1.4%, and 0.4%. Crowding only in the maxilla was found in 9.6%, while that only in the mandible and in both arches was 14.1% and 24.1% respectively. Spacing only in the maxilla was seen in 3.0%, while that only in the mandible and in both arches was 2.4% and 1.7% respectively. Significant difference in self-esteem was revealed in female and malocclusion groups of crossbite and openbite(p < 0.05).