• Journal of Yeungnam Medical Science
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• 제37권3호
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• pp.169-178
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• 2020

Glass ionomer cement (GIC) is a tailor-made material that is used as a filling material in dentistry. GIC is cured by an acid-base reaction consisting of a glass filler and ionic polymers. When the glass filler and ionic polymers are mixed, ionic bonds of the material itself are formed. In addition, the extra polymer anion reacts with calcium in enamel or dentin to increase adhesion to the tooth tissue. GICs are widely used as adhesives for artificial crowns or orthodontic brackets, and are also used as tooth repair material, cavity liner, and filling materials. In this review, the current status of GIC research and development and its prospects for the future have been discussed in detail.

• The Journal of the Korean dental association
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• 제16권3호통권106호
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• pp.193-195
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• 1978

The author observed the effect of x-ray irradiation on the tooth germ development of the rat fetuses. The lower right abdomen of the pregnant rats were exposed to x-ray irradiation (400 rads) on 9½th day of qestation. At 18½th day of qestation, the fetuses were removed from their mothers and histological sections of molar region were prepared. The results were as folows: 1. In the experimental fetuses, no significant changes appeared in the histological aspects of the enamel pulp, except the poor development of the innerenamel epithelium in the cusp region. 2. Pulp cells of cusp region in the irradiated fetuses were not differentiated to odontoblasts, The arrangement and population of pulp cells showed marked regional differences in the dental papilla. 3. Developmental features of dental follicle of irradiated fetuses were similar with controls.

• Journal of Korean Dental Science
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• 제15권2호
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• pp.172-180
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• 2022

Ameloblastic fibro-odontoma (AFO) is a rare odontogenic tumor, which occurs in young children before the age of 20 years. Radiologically, it is a well-defined radiolucent lesion containing radiopaque masses. Histopathologically, AFO is composed of odontogenic epithelium in a primitive-appearing connective tissue and hard tissue consisting of enamel and dentin. It is commonly found in the mandibular posterior region. AFO may be asymptomatic and is often associated with delayed tooth eruption. As it shows similar characteristics clinically and radiologically to odontoma, differential diagnosis through histopathological examination is important. Treatment of AFO is conservative enucleation, and teeth enclosed or associated with the lesion may require extraction. In this report, 2 young patients who visited our clinic with a chief complaint of delayed eruption were diagnosed as AFO with radiological and histopathological examination. After the surgery, the healing status was found to be favorable, and no evidence of recurrence was observed.

• Journal of the korean academy of Pediatric Dentistry
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• 제31권3호
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• pp.495-500
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• 2004

Dens invaginatus is a malformation of tooth resulting from an infolding of the enamel epithelium during tooth development. This malformation shows a broad spectrum of morphologic variations. This invagination frequently allows the entry of irritants and microorganism, which usually lead to necrosis of the adjacent pulp tissue and then to periapical or periodontal abscess. Root canal treatment of such tooth is often difficult because of the un usual form and complicated pulpal space. This article reports 2 cases of dens invaginatus in maxillary lateral incisors. The first case was successfully treated with $Ca(OH)_2$. In the second case, involved tooth was extracted and this extracted tooth was observed using the micro-computed tomography.

• Journal of the korean academy of Pediatric Dentistry
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• 제32권2호
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• pp.224-228
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• 2005

The effect of primary tooth infection on permanent teeth was reported by many previous study. It is seen histologic change in the enamel forming organ and in the surrounding sac, thus produce the defect as either hypoplasia or hypocalcification and alter the eruption of the permanent teeth. The periapical inflammation cause permanent tooth displacement in various direction and can be classified into the three categories : rotation, deflection inversion. This study reported case which displacement of succedaneous teeth may be caused by periapical infection of primary dentition and concluded that treatment procedure of infected primary tooth is selected and performed by importance to retain the tooth for space maintain, possibility to successfully restored, evidence of abnormal development of the succedaneous tooth.

• Journal of dental hygiene science
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• 제20권4호
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• pp.252-260
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• 2020

Background: In this study, the bleaching effect and surface damage of two types of over-the-counter home tooth bleaching agents were explored using an in vitro study of bleaching agents applied to bovine teeth specimens for 14 days. Methods: Domestic over-the-counter home tooth bleaching agents of gel and patch form that shared common active ingredients and manufacturers were selected and tested. The experiment specimens were made using composite resin with bovine tooth samples and then measured the initial microhardness. Specimens were then divided into a Gel group and a Patch group and underwent bleaching treatment once a day for two weeks for 30 to 60 minutes (recommended) or 7 hours. All specimens were coffee-stained prior to bleaching. The bleaching effect was measured using a spectrophotometer and surface damage was measured using a microhardness meter. Results: The difference in color following the bleaching procedure was positive in both the Gel and Patch group, although there were no statistically significant differences in bleaching effect between groups. There was no significant difference in bleaching effect based on duration. The microhardness test revealed that both the Gel group and the Patch group had surface damage after bleaching. The greatest surface damage was found in the Patch group that had undergone a 7-hour bleaching treatment, although the differences were not statistically significant. Conclusion: The bleaching effect of the home tooth bleaching agent was visible to the naked eye. However, longer applications than recommended did not result in greater bleaching, unlike consumers' expectations, and instead increased the chance of enamel damage. As such, there is a need for consumers to be alert and adhere to recommendations provided by each company.

• Journal of the Korean Society for Precision Engineering
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• 제27권4호
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• pp.87-94
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• 2010

When occlusal force is applied to a tooth, stress concentration occurs on the dental cervical line. This study investigated to find the maximum force and strain of natural teeth using an Instron and strain gauges, comparing the strain of cervical enamel using finite element analysis(FEA). Tests were conducted with a mandibular first premolar applying the conditions of occlusion. Then, the FEA was processed with the same as conditions of the fracture test. The test showed that the maximum force, maximum compressive strain and maximum tensional strain was $278{\pm}26$ N, $0.668{\times}10^{-3}{\pm}0.678{\times}10^{-3}$ and $0.248{\times}10^{-3}{\pm}0.102{\times}10^{-3}$, respectively. It was found that six of eight measured strains were within the range of estimated strains by the FEA. Even though it was assumed that properties of FE models were isotropic, it could prove useful as a reference in understanding the tendency of dental strain.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제23권4호
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• pp.332-337
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• 2001

An odontoma is a slow growing and nonaggressive odontogenic tumor composed of enamel, dentin, cementum, and pulp tissue. The etiology of odontomas is unknown, although local trauma, infection, and genetic factors have been suggested. Odontomas are classified as compound odontoma or complex. A 20-year retrospective study was performed on 36 odontomas from the files of the Department of Oral Pathology at Chosun University School of Dentistry. Fifty-six percent of the patients were compound odontoma and 44% were complex odontoma. 56 percent of the patients were female and 44% were male. The odontoma is most often diagnosed in the second decade of life, during routine radiographic examination. The usual presenting symptoms are an impacted or and unerupted tooth, a retained primary tooth. Other less frequent signs and symptoms are pain, swelling, suppuration, foul odor, tooth mobility. In our patients were treated by enucleation of the tumor, and related teeth were treated by surgical extraction or orthodontically assisted eruption.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• 제10권1호
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• pp.9-14
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• 1980

The author studied on the effects of X-ray irradiation to the development of periodontal ligament in gestation rats. They were irradiated in their abdomen with 100, 200 and 300 rads respectively in one shot irradiation with deep radiation therapy equipment (MAXIMAR 250-Ⅲ), In 7th, 14th, 21th and 28th day after delivery, those new born rats were respectively sacrificed with ether anesthesia and removed of their mandibles. After removal, those mandibles were fixed in 10% neutral buffer formalin, decalcified with 5% trichloroacetic acid for 5 days and embedded with paraffine. Staining was performed with H-E, Van Gieson, Mallory azan, Bielshowsky-Gomori silver stain and Halmi's oxytalan fiber stain. The results were as follows: 1. Before tooth eruption, all the fiber: components in dental sac were almost always oriented near the outer enamel epithelial \layer. But in irradiated new born rats, those collagen fiber orientation was more irregular than those of control groups, and this phenomenon was more severe in proportion to the amount of irradiation in the gestation period. 2. Before tooth eruption, the connective tissue fibers in periodontal ligament were stained with lighter in the irradiated groups than those of control groups. Oxytalan fibers of irradiated groups were thin and splitting pattern of their fiber morphology to compare with those of control groups. 3. After tooth eruption, the periodontal ligament fibers of irradiated groups were oriented functionally and their morphology was thick, fine and heavy staining. Oxytalan fibers were revealed with oblique parallel arrangement in the periodontal ligament of irradiated groups.

• Restorative Dentistry and Endodontics
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• 제18권2호
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• pp.413-422
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• 1993

The purpose of this study was to evaluate the adaptation of light cured glass ionomer cement and composite resin using all- etch technique to tooth structure. In this study, class V cavities were prepared on the buccal surfaces of 10 extracted human premolar teeth with cementum margin and teeth were randomly assigned 2 groups of 5 teeth each. The cavities of glass ionomer cement group were filled with the light cured glass ionomer cement(Fuji II LC) and the cavities of composite resin group were filled with the light cured composite resion(P - 50) using all- etch technique with All- Bond 2. The restored teeth were stored in 100 % relative humidity at $37^{\circ}C$ for 48 hours. And then, the roots of the teeth were removed with the tapered fissure bur and the remaining crowns were sectioned occlusogingivally through the center of restorations. Adaptation at tooth - restoration interface were assessed occlusally, gingivally, and axially by scanning electron microscope. The results were as follows : 1. The adaptation to enamel walls of composite resin restorations using All - Bond 2 showed better than glass ionomer restorations. 2. The adaptation to gingival and axial walls of glass ionomer restorations showed better than composite resin restorations using All - Bond 2. 3. In both groups, occlusal margins of restorations showed better adaptation than gingival margins of restorations.