• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.17 no.1
• /
• pp.271-278
• /
• 1987

The purpose of the present study was to investigate associations between periapical and bitewing techniques by assessing the crestal alveolar bone. This article also reports the ability of these two techniques to correctly detect evidence of interproximal dental caries, and comparison between the interproximal overlapping of teeth. Bitewing and periapical radiographs were used from posterior quardants of 243 dental students in Seoul National University. The distance from cemento-enamel junction to the alveolar crest (CEJ-AC) was measured for each proximal surface from the distal of cuspid to the distal of second molar. Data were arranged according to the proximal surface examined, and bitewing and periapical measurements were compared using paired tests. The obtained results were as follows: 1. In maxilla, a significant t ratio with a P value of 0.05 or less reached for 100% and in mandible, reached for 94%. 2. The anatomic limitations imposed on periapical radiographic technique, most often result in somewhat foreshortened radiographic images. This situation would tend to be accentuated by the anatomical restrictions of the hard palate. 3. Consequently, since the significant differences frequently exist between measurements obtained from bitewing and periapical techniques, it is important to define which technique is used. 4. The number of the interproximal overlapping was the largest medial side of the maxillary second molar, while the smallest at the distal side of the mandibular second premolar. And the overall number of the interproximal overlapping was more (538) in the periapical technique than in the bitewing technique (372). 5. The interproximal dental carious lesions were detected more (74) on the bitewing films than on the periapical ones (23). The fact was resulted from the small number of interproximal overlapping and relative easi- ness of obtaining horizontal angulation in taking the bitewing radiographs.

• Imaging Science in Dentistry
• /
• v.41 no.2
• /
• pp.71-78
• /
• 2011

Purpose : This study was performed to determine the optimal tile size for the fractal dimension of the mandibular trabecular bone using a tile counting method. Materials and Methods : Digital intraoral radiographic images were obtained at the mandibular angle, molar, premolar, and incisor regions of 29 human dry mandibles. After preprocessing, the parameters representing morphometric characteristics of the trabecular bone were calculated. The fractal dimensions of the processed images were analyzed in various tile sizes by the tile counting method. Results : The optimal range of tile size was 0.132 mm to 0.396 mm for the fractal dimension using the tile counting method. The sizes were closely related to the morphometric parameters. Conclusion : The fractal dimension of mandibular trabecular bone, as calculated with the tile counting method, can be best characterized with a range of tile sizes from 0.132 to 0.396 mm.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.36 no.6
• /
• pp.528-532
• /
• 2010

Introduction: There are few reports on tooth eruption through Bio-Oss grafts. To our knowledge, there are no reports on whether teeth can erupt normally through the grafts. The aim of this study was to examine the effect of Bio-Oss grafts on tooth eruption in a canine model. Materials and Methods: In five 10-week-old dogs, the deciduous third mandibular molars in one jaw quadrant of each animal were extracted and the fresh extraction sockets were then filled with Bio-Oss particles (experimental side). No such treatments were performed on the contralateral side (control side). A clinical and radiological evaluation was carried out every other week to evaluate the eruption level of the permanent third mandibular premolars and compare the eruption levels between the two sides. Results: At week 4 after the experiment, the permanent third premolars began to erupt on both sides. At week 12, the crown of the permanent third premolar emerged from the gingiva on both sides. At week 20, the permanent third premolars on both sides erupted enough to occlude the opposing teeth. No significant differences were found between the control and experimental sides in terms of the eruption speed of the permanent third molars. Conclusion: These findings demonstrate that the grafting of Bio-Oss particles into the alveolar bone defects does not affect tooth eruption.

• The Journal of Korean Academy of Prosthodontics
• /
• v.38 no.5
• /
• pp.606-617
• /
• 2000

The purpose of this study was to measure the marginal fidelities and the fracture strength of IPS Empress $2^{(R)}\;and\;In-Ceram^{(R)}$ ceramic crowns. After constructed of 12 experimental dies for each group, ceramic crowns were fabricated on the metal master dies prepared on the maxillary right premolar Marginal gaps were measured on the specimen between the margin of each crown and finish-ing line of the metal master die by using stereo-microscope($SZ-ST^{(R)}$ Olympus, Japan) and all specimens were cemented on the metal master die with Bistite $II^{(R)}$ (Tokuyama soda Co, LTD., Japan) resin cement. Finally marginal gaps were measured again. To measure of the fracture strength, buccal incline on the functional cusp of specimens were loaded until the catastrophic failure occurred by using the AGS-1000 $D^{(R)}$(Shimadzu, Japan). The result of marginal fidelities and fracture strength were statistically analyzed with the SPSS version 8.0 programs. The results of this study were as follows : 1. No significant difference was found in the mean marginal fidelities and fracture strength between the IPS Empress $2^{(R)}\;and\;In-Ceram^{(R)}$. 2. In comparison of marginal fidelities between before and after cementation, there was significant difference(P<0.05). The IPS Empress 2 system was shown in this study that had good marginal fidelities and fracture strength compared to In-Ceram ceramics. Although this system was acceptable to clinical applications, the system still has to be considered long-term researches about marginal fidelities and fracture strength due to the lack of data about the clinical researches.

• Journal of Periodontal and Implant Science
• /
• v.23 no.1
• /
• pp.127-134
• /
• 1993

The purpose of this study was to observe the control effect of hypersensitivity after periodontal treatment in the 19% microcrystalline hydroxyapatite containing toothpaste for the subject of 85 persons of both sexes, who complained hypersensitivity. At 2 weeks and 4 weeks after periodontal treatment, comparison of control effect was performed between the 19% microcrystalline hydroxyapatite containing toothpaste group and control group. The result were as follows, 1. The main causes of dentin hypersensitivity are the root exposure with gingival recession and cervical abrasion. 2. The occurance rate of hypersensitive tooth in the upper jaw was higher than that of the lower jaw, and more or less, the molar area showed more occlurance of hypersensitivity than the premolar and incisor area in both jaw. 3. Patients showed very sensitive response to the thermal stimulus, especially cold stimulus. 4. Exellent control effect of hypersensitivity in 19% microcrystalline hydroxyapatite containing toothpaste group showed 83.02% at 2weeks, 92.45% at 4weeks and these values were higher than the control group. In conclusion, we find that 19% microcrystalline hydroxyapatite containing toothpaste have the control effect of hypersensitivity and the proper toothbrushing method is the key in attaining more effectiveness of the toothpaste.

• Journal of Periodontal and Implant Science
• /
• v.26 no.3
• /
• pp.669-679
• /
• 1996

Gingival overgrowth is a well known side effect of several drugs, including nifedipine, phenytoin, cyclosporin, dilitiazem, verapamil. A number of studies have been performed to investigate the mechanism by which nifedipine(a calcium channel blocking agent) affects the gingival tissue. The aim of the present work was to investigate the effect of nifedipine on healthy gingival fibroblasts with special emphasis on determining the changes in cellular proliferation and protein and collagen synthesis. Gingival fibroblasts were obtained from the explants of healthy gingiva of extracted 3rd molars or premolar teeth extracted from the patients for orthodontic treatment. To evaluate the effect of nifedipine on cell proliferation, the cells were seeded at a cell density of $1{\times}10^4$cells/well in 24-well culture plates and treated with 100 and 200ng/ml of nifedipine for 10days. After trypsinization, the cells were counted with a haemocytometer on 1st, 3rd, 5th, 7th and 10th days. Then, MTT assay was carried out. For total protein and percent collagen synthesis, $3{\mu}Ci/ml$ $^3H-proline$ was added to each well for the final 4 hours of the incubation period. The results indicate that nifedipine does not influence cell proliferation in healthy gingival fibroblast in vitro and has a specific effect in reducing total protein and percent collagen synthesis. On the above the findings, exogenous nifedipine does not influence on healthy human gingival fibroblast proliferation and protein and collagen synthesis.

• The Journal of Korean Academy of Prosthodontics
• /
• v.26 no.1
• /
• pp.153-169
• /
• 1988

There is a little scientific documentation reporting the stress, distribution to the edentulous mandible by different concepts of occlusal scheme. So, this study was to investigate the hypothesis that the magnitude and distribution of the occlusal stresses, transmitted through a mandibular complete denture base to the edentulous mandible, would be influenced by the lingualized occlusion. This investigation was performed to analyze the stresses induced in a three-dimensional photoelastic edentulous mandible, when a load is applied to the denture arranged into lingualized occlusion in centric relation, lateral and protrusive functional position. The mounted denture on a Dentatus Type ARO articulator was loaded in a pure vertical direction with 15kgs on the center of articulator in each case and the stresses were frozen into epoxy edentulous model at $127^{\circ}C$ in the stress freezing furnace. The stress-frozen epoxy models were sliced with diamond disc saw into 4mm thick. The slices were examined with a circular polariscope. The results were as follows: 1. In centric relation, the stresses were low at anteriors, and gradually increase to the premolar, molar area and highest at the first molar and gradually decrease from the second molar and lowest at the retromolar pad region. The lingual side showed higher stresses than labiobuccal side. 2. In lateral functional position, the working side showed higher stresses than the balancing side. In working side, the lingual side showed higher stresses than the buccal side and in balancing side, the buccal side showed higher stresses than the lingual side. 3. In protrusive position, stress distribution was symmetrical on the posteriors and the stresses were concentrated at the labial side of the anteriors.

• Journal of Periodontal and Implant Science
• /
• v.38 no.4
• /
• pp.621-628
• /
• 2008

Purpose: Osteopontin is one of the major non-collagenous protein of hard tissue. Use of peptide domain of biologically active protein has some advantages. The objective of this experimental study is evaluation of periodontal regenerative potency of synthetic peptide gel which containing collagen binding domain of osteopontin in the degree III periodontal defect of beagle dogs. Material and Methods: Experimental degree III furcation defect was made in the mandibular third and fourth premolar of beagles. Regenerative material was applied during flap operation. 8 weeks after regenerative surgery, all animals were sacrificed and histomorphometric measurement was performed to calculate the linear percentage of the new cementum formation and the volume percentage of new bone formation. Result: The linear percent of new cementum formation was 41.6% at control group and 67.1% at test group and there was statistically significant difference. The volume percent of new bone formation was 52.1% at control group and 58.9% at test group. Conclusion: As the results of present experiment, synthetic peptide gel containing collagen binding domain of osteopontin significantly increase new bone and cementum formation in the degree III furcation defect of canine mandible.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.42 no.1
• /
• pp.22-29
• /
• 2015

The purpose of this study was to evaluate the eruption patterns of mandibular premolars associated with dentigerous cysts after marsupialization regarding the depth, angulation and root development of impacted teeth. Spontaneous eruption was found in 93% of mandibular premolars after marsupialization. Eruption speed and rate of angulation change were greater in mandibular premolars associated with a cyst than those on the non-cyst side. The group with less matured roots tended to have greater eruption speed and angulation change. The eruption speed and angulation change declined rapidly during the first 6 months after marsupialization. Based on the results of this study, it might be possible to predict the eruption pattern of mandibular premolars associated with a cyst after marsupialization, which would be useful for treatment planning.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.47 no.2
• /
• pp.213-218
• /
• 2020

The loosely structured periodontal ligament and low mineralized bone surrounding erupting teeth provide minimal resistance to an extrusive force. The maxillary central incisors are the most frequently avulsed due to trauma. The prognosis of replanted teeth is affected by extra-alveolar period and conditions. Implant-supported restorations are contraindicated in adolescent patients with poor prognosis traumatized teeth. Autotransplantation of premolar to the anterior region provides a viable treatment alternative. This case report describes the autotransplantation of premolars and esthetic rehabilitation in a teenage patient with traumatized incisors, poor oral hygiene, and severe crowding. Comprehensive and long-term treatments were performed to improve complex and challenging oral problems.