• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.1-28
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• 1990

The severe atrophic edentulism with poor neuromuscular control militates against successful conventional denture therapy. To such situation, a prescribing of dental implant treatment has been considered with some probability. Implant materials used as a trial for dental implants includes metals, plastic polymers and ceramics. The purpose of this study was to observe histologic response in osseointegration process at titanium implant-tissue interface based on biocompatibility at specific period of sequential natures which were divided into a half month, one, month, two months, three months and immediate as a base line. In this study, unilateral lower left premolar and molar teeth were extraced in three dogs. After allowing to heal for 6 months, three kinds of osseointegrated implant, $Br{\aa}nemark$, Corevent and kimplant(a prototype of SNU implant study)were inserted in each dog respectively according to the above sequence from front to back. The specimens were taken from those dogs at the same time since implant were inserted quite reverse order of the specified periods, and decalcified and processed for histologic examination for the light microscopy and the electron microscopy. The microscopic histologic findings at the interface between titanium implants and tissue were interpretated as follows : A. Light microscopic findings : a. Immediate : Implant were surrounded by compact bone and spongy bone. Microcrak was observed in the superficial bone tissue. Osteocytes were disappeared and bone lacunae were observed as a vacant space in some parts. In the contacting with the spongy bone, bone trabeculae and bone marrow were in contact with the implant. b. A half Month : Osteoblasts exist as a monolayer in th inner bone trabeculae and do bone additiocn. Osteoblasts&inflammatory cells were observed in some parts. c. One Month : The presence of osteoclasts decreased. Osteoblasts did active bone fromation, and bone marrow was in contact with the implant in the many places. d. Two Months : Bone formation was advanced in comparison with the b and c. The presence of osteoclsts was not observed. e. Three Months : The superficial bone tissue contacted with the implants was entirely composed by the compact bone. B. Electron microscopic findings : a. A half month and one month group : In the parts of the active bone formation, osteoblasts with the well developed endoplasmic reticulum and Golgi apparatus were arranged in the monolayer. In the parts of the bone resorption, ruffled border was well developed and many osteoclasts with the well-developed golgi apparatus, mitochondria, vacuole, vesicle and lysosome were existed. b. Three months group : No osteoblasts were observed in the superficial bone tissue. Bone matrix with collaen fiber was observed. c. No significant dirrerence in the histologic findings was observed in $Br{\aa}nemark$, Core-vent and kimplant.

• Restorative Dentistry and Endodontics
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• v.14 no.1
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• pp.109-118
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• 1989

The purpose of this study was to investigate the bio-stimulating effect of low power density laser radiation on the mechanically exposed pulp. Class V cavities on dog's teeth were prepared and the pulps were mechanically exposed with a round bur. In control group, the exposed pulps were capped with $Ca(OH)_2$ powder and the cavities were sealed with Z.O.E.. In experimental group A, the pulps were irradiated with GaA1As laser for 5 minutes and then they were treated the same as control group. In experimental group B, the exposed pulps were covered by aluminum foil and sealed with Z.O.E. after they were irradiated with the laser as the experimental group A. In the all groups, the pulps were histopathologically observed at the time intervals of 1, 2 and 3 week after experiment and the results were statistically evaluated. The results were as follows: 1) In control and experimental groups, mild vascular congestion and bleeding was found in most of the specimens and for the new formation of dentin bridge, experimental group A had the most cases. The dentin bridge had discontinuous osteodentin like appearance without any dentinal tubules. Inflammatory cell infiltration consisted of acute and chronic inflammatory cell, and the formation of microabscess was also observed. 2) The degree of inflammatory cell infiltration was not significantly different among control group and experimental groups at 1 week, 2 week and 3 week. 3) The formation of new dentin bridge was not significantly different between control group and experimental group A at 1 week, but at 2 week and 3 week, experimental group A showed significantly more cases of new dentin formation than control groups. (P < 0.05). 4) Between control group and experimental group B, there was no significant difference in formation of the new dentin bridge at 1, 2 and 3 week. (P> 0.05). 5) There was no significant difference in formation of the new dentin bridge at 1 and 2 week between experimental group A and experimental group B, but at 3 week, the former significantly had more cases of new dentin bridge formation than the latter.(P < 0.05).

• Journal of Periodontal and Implant Science
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• v.37 no.2
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• pp.237-249
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• 2007

This study was performed to evaluate the effect of membrane exposure on new bone formation when guided bone regeneration with perforated titanium membrane on atrophic alveolar ridge. The present study attempted to establish a GBR model for four adult beagle dog premolar. Intra-marrow penetration defects were created on the alveolar ridge(twelve weeks after extraction) on the mandibular premolar teeth in the beagle dogs. Space providing perforated titanium membrane with various graft material were implanted to provide for GBR. The graft material were demineralized bovine bone(DBB), Irradiated cancellous bone(ICB) and demineralized human bone powder(DFDB). The gingival flap were advanced to cover the membranes and sutured. Seven sites experienced wound failure within 2-3weeks postsurgery resulting in membrane exposure. The animals were euthanized at 4 weeks postsurgery for histologic and histometric analysis. The results of this study were as follows: 1. There was little new bone formation at 4 weeks postsurgery. irrespectively of membrane exposure. 2. There was significant relationship between membrane exposure and bone graft resorption(P<0.05), but no relation between membrane exposure and infiltrated connective tissue. 3. There was much bone graft resorption on DFDB than ICB and DBB. 4. The less exposure was on the perforated titanium membrane, the more dense infiltrated connective tissue was filled under the membrane when grafted with ICB and DBB. but there was no relationship between the rate of membrane exposure and the percentage of infiltrated connective tissue area and no relationship between the percentage of the area in the infiltrated connective tissue and in the residual bone graft. Within the above results, bone formation may be inhibited when membrane was exposed and ICB and DBB were more effective than DFDB as a bone graft material when guided bone regeneration.

• Journal of Periodontal and Implant Science
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• v.29 no.1
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• pp.1-14
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• 1999

Ursodeoxycholic acid(UDCA) is a hydrophilic gall bladder acid and has been used as a effective drug for liver disease related to in1munity. This drug inhibits secretions of IL-2, IL-4, and $IFN-{\gamma}$ from T-cells and production of immunoglobulin from B-cells. Also it has been reported that UDCA inhibits production of IL-1 related to the progression of periodontal disease and activation of collagenases. The purpose of the present study was to elucidate the effects of UDCA on inhibition of periodontal disease progression using clinical, microbiological and histometrical parameters. Twelve pure bred, 16 month-old-beagle dogs were used in the study. After ligature-induced periodontal diseases were formed, experimental drugs were applied twice a day and then the results of clinical, microbiological, and histometrical parameters were measured at baselie(initiation of experiment) , 4weeks and 8weeks. The gel with UDCA(concentration 0.5%, 5% 3 dogs in each) was applied to experimental group, chlorhexidine to positive control group(3dogs) and the gel without UDCA(base) to negative control group. After induction of general anesthesia, the maxillary 2nd, 3rd premolars and 1st molar and the mandibular 2nd, 3rd, 4th premolars and 1st molar were ligated in one side selected randomly and were not ligated in the opposite side. The plaque index(PI), gingival index(GI), pocket depth(PD) and gingival crevicular fluid(GCF) volum were measured clinically. The PI and GI were measured at 3 buccal points of all experimental teeth and the GCF was measured only at the 3rd premolar in the maxilla and the 4th premolar in the mandible. In the microbiological study, the samples extracted from the 3rd premolar of the maxilla and the 4th premolar of the mandible at the center of buccal surface were analyzed aerobics, anaerobics and Streptococcus colony forming units, After clinical and microbiological examination at 8weeks, the dogs were sacrificed by carotid artery perfusion. The samples were fixed and sectioned including interproximal area, and the distance from cementoenamel junction(CEJ) to alveolar crest was measured. The results were that PI, GI and PD increased until 4 weeks and decreased at 8 weeks in three groups but the differences between all the groups were not significant. The 0.5% UDCA in non-ligated group showed remarkable decrease of GCF. The experimental group applied 5% UDCA decreased the number of aerobics and anaerobics. The distance from CEJ to alveolar crest was greater in the negative control group on both ligated and non-ligated sides, but the differences were not significant stastically.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.317-333
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• 2000

The purpose of this study was to determine the proliferative activity of the osteoblasts and fibroblasts in the midpalatal area and to investigate the adjacent periodontal tissues of individual tooth following rapid expansion of the palate. Ten young adult dogs, aged approximately ten months, were used in the experiment. The experimental design was consisted of 1 week expansion group(Group E1, 3 dogs), 2 week expansion group(Group E2, 3 dogs), 2 week expansion and 2 week retention group(Group E3, 3 dogs), and control group(Group C, 1 dog). For each group, expansion screw was activated one time per day(1/4 turn;$90^{\circ}$) following Hyrax-screw application. The experimental animals in each group were sacrificed at 1, 2 and 4 weeks following palatal expansion. Maxillary tissue blocks were obtained and prepared ior the histomorphologic and immunohistochemical studies. Light mcroscope, polarizing microscope, and soft X-ray apparatus were used in this study, and following results were obtained. 1. In polarizing microscopic study, the expansion groups(E1 & E2) showed blue color representing bone resorption and new bone formation in midpalatal suture area. E3 groups skewed less blue color compared to the E1 and E2 group. But yellow color increased by calcification in the E3 groups. 2. Immunohistochemical study revealed that positive responses of the osteoblasts to PCNA and undifferentiated fibroblasts to EGF in E1 group were somewhat increased. Positive response to PCNA and EGF were increased in fibroblasts and the osteoblasts forming new bone in E2 group. In E3 group, the positive response cell concentrated the periphery of edge of palatal process in both PCNA and EGF. 3. Throughout the expansion period(E1 & E2), light microscopic study showed the edges of the extensive resorption and new palatal processes, indicating bone remodeling within the suture. E3 group exhibited less remodeling of midpalatal suture area. E2 group and E3 group showed cementum formation and resorption at the apex of 3rd premolar and 1st molar E3 group exhibited extensive hyalinized zone on the cervical portion of buccal side of 1st molar. 4. Soft X-ray analysis of E1 group showed hypomineralized defect and microfractures in various parts of the suture areas when compared with control animals. There was no significant difference in the degree of mineralization in the midpalatal suture region between the C and E3 groups. Tooth axis showed tipping of 3rd premolar and 1st molar in the E2 group and E3 group. Based upon these experimental results, it is concluded that the undifferentiated mesenchymal cells always presented in midpalatal suture area following RPE. Differentiated osteoblasts and fibroblasts possess proliferating cellular activity until the 2 week retention period. The posterior teeth are tend to tip buccally as RPE force applied. Retention group exhibited irreversible response with severe hyalinized zone on the buccal surface of the first molar.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.318-332
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• 2000

The purpose of this study was to investigate the effects of demineralized freeze-dried bone (DFDB) on mechanically exposed pulp of dog by evaluating the pulpal inflammation and healing process, formation of dental hard tissue, and structural changes of fibroblasts of the remaining pulp tissue. Teeth of 4 dogs, weighing 10kg, were used in this study. Class V cavities were prepared followed by exposed the pulp tissue mechanically by sterilized round bur. In control group, exposed pulps were capped with calcium hydroxide paste followed by sealed with IRM. In experimental groups, the exposed pulps of one group were capped with the collagen and those of the other group were capped with DFDB. All cavities were sealed with same manor as control group. The animals were sacrificed at the intervals of 3, 7, 14, and 28 days for histopathlogic evaluation. The specimens were observed by the light microscope and trans-electron microscope. The results were as follows: 1. Pulp necrosis was not observed in all groups. Inflammatory response was disappeared from 1 week in control group and group 2. But it was not disappeared until 2 weeks and also irregular arrangement of odontoblasts was showed at the lateral walls of root canal just beneath the amputated site of the pulp in group 1. 2. Dentinal bridge was formed incompletely at 2 weeks but it was formed completely at 4 weeks in control group. Odontoid tissue was also found in control group at 4 weeks from treatment. Amputated site of pulp was encapsulated with fibrous tissue and odontoblast and dentinal bridge was not found in group 1. Preodontoid tissue and reparative dentin which were formed by odontoblast differentiated around DFDB were found, but dentinal bridge was not found in group 2. 3. Cell with large basophillic-stained nuclei infiltrated to amputated site and DFDB at 1 week from treatment in control group and group 2. They were found more in group 2 than in control group. Odontoblasts arranged more regularly and reparative dentin was found more as time elapsed. 4. Dentin-formative odontoblasts which showed ultramicrostructure of cytoplasm with polarized nucleus, rEM, Golgi complex, secretory granules, secretion of organic matrix in control of group and group 2. In regards to above results, the demineralized freeze-dried bone(DFDB) induce odontoblastic differentiation and further come up to the dentin formation in amputated pulp.