• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.77-97
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• 1989

The purpose of this study was to observe the effect of ${\beta}GP$ in the remaining dental pulp tissue after pulpotomy in the dogs' teeth. For vital pulpotomy, 72 dogs' teeth were used and class V cavities were prepared and the pulps were amputated. ZOE and Dycal (Caulk Co., USA) were placed over the amputated tissue and cavities were sealed with ZOE cement in the control group. In the experimental group, ${\beta}GP$, ${\beta}GP$-ZOE, ${\beta}GP$-Dycal were placed over the exposed pulp tissues respectively. Dogs were sacrificed after 1, 2 and 4 weeks following the operations and the teeth were decalcified in the nitric acid, sectioned and stained with HE for light microscopic examination. For electron microscopic examination, specimens were made after 2 and 4 weeks following the operation. A comparative microscopic examination revealed as follows. 1. The dentin bridge was formed continuously due to osteodentin in the ${\beta}GP$-Dycal group at the 2nd week, the dentin bridge composed of osteodentin and tubular dentin was observed at the 4th week. 2. Osteodentin formation was vigorously in the ${\beta}GP$-Dycal than in the Dycal group. 3. In the surface of osteodentin the osteodentinoblasts showing vivid synthetic activity were observed and the matrix vesicles were presented during calcification of osteoid dentin matrix. 4. The dentin bridge formation was not observed in ${\beta}GP$ group and ${\beta}GP$-ZOE group.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.6 no.1
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• pp.15-18
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• 1976

The authors has observed the effect of X-ray irradiation on the dentin matrix formation of the albino rat fetuses. The lower abdomen of the pregnant ratswere exposed to X-ray on the 9 1/2th day of gestation, respectively 150, 250 and 350 rads. The fetuses of the right sides of the same pregnant rats which were not exposed to X-ray were as controls. The results were as follows: 1) In the 150 rads irradiated fetuses, predentin formation was identical with control groups, but the arrangement of odontoblasts was distorted, subodontoblastic layer was condesed with pulp cells and blood capillaries were enlarged. 2) In the 250 rads irradiation, dentin matrix was imperfact or osteodentin was occured. Short columnar or cuboidal odontoblasts were presented and pulp cells were dispersed. Blood capillaries were cogested. 3) 350 rads irradiated fetuses showed osteodentin matrix and numerous degenerated odontoblasts. Their dental papilla showed reticular atrophy and enlarged capillary.

• Journal of dental hygiene science
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• v.10 no.5
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• pp.395-401
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• 2010

Over expression of TGF-${\beta}1$ revealed the same phenotype as NFI-C deficient mouse. It has been reported that NFI-C deficient mice demonstrated abnormal odontoblast differentiation and aberrant dentin formation during root development. In the present study, in order to investigate the histological differences between wild type (WT) mouse and NFI-C deficient mouse, we compared morphological characteristics and smad4 expression between those mice. Hematoxyline-eosin (H-E) staining was used to investigate morphological changes and immunohistochemistry was also performed to observe the Smad4 expression pattern. In H-E staining, incisor of NFI-C deficient mouse showed an open area in the lingual root, irregular odontoblasts and osteodentin. Also, NFI-C deficient mouse showed short root and osteodentin in molar. In addition, Smad4 protein was strongly expressed in NFI-C deficient mouse compared with wild type. These findings suggest that NFI-C deficiency affects odontoblast differentiation and result in the formation of abnormal roots. Therefore, balancing between NFI-C and TGF-${\beta}$ signaling including Smad4 is important for the regulation of normal odontoblast differentiation and dentin formation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.19 no.1
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• pp.39-48
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• 1989

Six to eight-month-old female albino rats were used as experimental animals. As an irradiation equipment, a Co-60 was used. The experimental animals were divided to; 6 of the control group, 12 of the 500cGy single irradiation group, 12 of the 1000cGy fractionated irradiation group, and 12 of the 1500cGy fractionated irradiation group. From the first week to the forth, 3 rats were picked from each group every week to be sacrificed and fixed with formalin. Those rats were observed by means of H-E stain after being taken radiograph and decalcified. The analysis of radiographic findings and light microscopic findings gives results as follows: 1. The delay of dental eruption rate was found in every group which underwent the irradiation experiment. Dentin niche, osteodentin, and dentin island were formed in the parts which were damaged by the irradiation. 2. The longer the observation period was, the more deposit of osteodentin and dentin island was formed. 3. In the single irradiation group, the damage effect was in proportion to the increase of radiation dose, whereas the damage was much less in the fractionated group receiving the same dose. 4. The 500cGy single irradiation group got temporary repairable damage, while the 1000cGy single irradiation group got considerable damage and showed much slower eruption rate than the 500cGy single irradiation group. The basal portion of the 1500cGy single irradiation group, whose growth was arrested, was destroyed. 5. The fractionated group were irradiated 500cGy everyweek. Repair was visible during the interval periods. The damage was accumulated as irradiation repeated, but degree of damage was lower than that of the 1000cGy and 1500cGy single irradiation group.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.205-215
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• 2008

The purpose of this study is to evaluate at which stage of tooth germ would develop into normal calcification and hence to increase the success rate of transplantation. Therefore, tooth germs on the 15th, 17th embryonic day and the 3rd day of birth were separated for allotransplantation into maxilla of adult rat of 11 weeks. Calcification processes were analyzed radiographically and histopathologically at 4 weeks and 8 weeks after allotransplantation. The results are as follows: 1. Allotransplanted tooth germ at 4 weeks and 8 weeks showed delayed calcification compared to that of normal odontogenesis. 2. At 4 weeks, abnormal calcified tissue, such as odontoma and ankylosis of osteodentin with surrounding alveolar bone were observed. 3. At 8 weeks, allotransplanted tooth germs of the 15th and 17th embryonic day showed calcification and osteodentin surrounded by periodontal ligament. 4. At 8 weeks, allotransplanted tooth germs of the 3rd day of birth showed calcification composed of cementum and osteodentin. In this study, we observed small sized and amorphous calcified tissue from allotropic allotransplantation of tooth germs. Since these calcified tissue were underdeveloped and shaped irregularly, for calcification into normal tooth form, further study needs consideration about the reduction of surgical trauma, developmental stage of transplanted tooth germ, blood supply from recipient site, fixation method in transplanted site and period of transplantation.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.35-42
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• 2006

The developmental process of a tooth is being presented as an important study subject to analyze formation of normal dental arch and tooth. The purpose of this study was to see the formation of tooth from a tooth bud transplanted in a white rat regarding that the jawbone could be used as a new donor site of a trasplant. The first molar of a matured white rat was extracted and the tooth bud of a 13.5 day rat embryo was transplanted. The histological and radiographical results after 4 and 8 weeks respectively are as the following. 1. Calcification in dentin, cementum, pulp and periodontal ligament was formed from the tooth bud transplanted in the alveolar socket. 2. The development of hard and soft tissue was delayed compared to the normal tooth formation and abnormal histologic features such as ankylosis and osteodentin were found. 3. The formed hard tissue did not erupt into the jaw within 8 weeks.

• The Journal of the Korean dental association
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• v.15 no.8
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• pp.611-615
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• 1977

The author observed histochemically the nature of the calcified tissue in the rabbit dental pulp, induced by pulpal injection of potassium permanganate. The pulp of rabbit mandibular incisors were exposed and enlarged by a dental hand reamer. The exposed pulps were injected with 0.05ml of 20mM solution of potassium permanganate dissolved in Ringer's solution in experimental tooth. Also the control tooth received a pulpal injection of 0.05ml of Ringer's solution. After pulpal injection, the tooth was plugged with a gutta-percha root canal point. The staining techniques were hematoxylin-eosin stain, van Gieson stain, PAS reaction, toluidine blue stain, alcian blue-hematoxylin stain and colloidal iron-picric acid stain. The results were as follows: 1. The pulp on experimental tooth showed osteodentin-like calcified tissue. Also, in some areas, false denticle-like substance were observed. 2. The central portion of the calcified matrix showed metachromasia in toluidine blue stain had strong staining capacity in alcian blue stain. 3. The peripheral portion of the calcified tissue revealed marked van Gieson positive reaction for collagen. But their staining ability in alcian blue was slight and metachromasia was not appeared.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.6 no.1
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• pp.33-38
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• 1976

The author observed the effects of the cobalt-60 irradiation on the amelogenesis and dentinogenesis of the albino rat fetuses by means of histological and histochemical methods. Females in oestrus were mated overnight and examined the next morning for evidence of copulation. The lower left abdomen of mothers were exposed to cobalt-60 irradiation on the 10th day of gestation, l00R 200R and 300R respectively. The fetuses were removed from the mothers on the 18th day of gestation. The employed histochemical methods were PAS reaction, colloidal iron reaction, aldehyde fuchsin stain, α-amino acid reaction, -SH radical reaction and methyl- green pyronin stain. The results were as follows; 1. The group irradiated by l00R made no histological differences in comparison with the control group. 2. Increasing the irradiation to 200R, abnormal dentin formation occured, and resulted in enamel hypoplasia and in atrophy and necrosis of odontoblasts. In dentinal papilla, the dilation and the degeneration of the blood vessels, excessive reticular atrophy and osteodentin were revealed. 3. With the more irradiation (200R-300R), the positive material of PAS, α-amino acid and aldehyde fuchsin tended to decrease in the ameloblast and the odontoblast. No significant changes appeared in DNA, the stainability of methylgreen pyronin.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.61-68
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• 1982

This study was undertaken to compare the histopathological effects of the fractionated doses of 2,400, 4,800 and 7,200 rads of Cobalt-60 irradiation on the teeth of the sixty eight rats (Wester strain), weighing approximately 130gm. They were devided into four groups; no irradiation as a control (Group I) and others (Group II, III, and IV) which received different doses of radiation using 1.25 Mev RAC-120 Cobalt-60 Teletherapy Unit with exposure dose rate 69 rads/min, TSD 80cm. Experimental animals received 600 rads every three days until the total dosage of their groups were reached. Experimental animals were sacrified at the 1st day, 1st, 2nd, 3rd, 4th, 5th and 6th week irradiation. The following histopathologic findings were obtained: 1. The Group II, received 2,400 rads, showed no histopamologic changes essentially same as those of the control Group. 2. In the Groups III and IV, received 4,800 rads and 7,200 rads, disarray of the normal palasading arrangement of the odontoblastic cells, vacuolar degeneration in the odontoblastic layer, osteodentin and dentinal niches in the anterior teeth were observed. 3. There were no distinct changes in the posterior teeth in the Groups III and IV. 4. The ameloblast cells seemed to be less sensitive to radiation damage than the odontoblast cells.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.718-724
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• 2007

A case of dentinal dysplasia type I is presented. Dentin dysplasia type I is a rare dental anomaly that is characterized by disturbance in dentin formation. It appears to be normal clinically, but, radiographically, it is characterized by obliteration of all pulp chambers and short, blunted, and malformed roots. Histological analysis shows whorls of tubular dentin and atypical osteodentin. In this case, features of dentin dysplasia type I in mixed dentition is presented. The clinical, radiographic, and histopathological findings of this condition are described along with its management.