• Journal of Biomedical Engineering Research
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• 제23권2호
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• pp.139-145
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• 2002

Bis-GMA, 2.2-bis[p(2-hydroxy-3-methacryloyloxypropokyl)phenyl]Propane, is an essential component as a multifunctional methacrylate prepolymer in the light-curable polymeric dental composite resins. Two hydroxyl groups of the Bis-GMA molecule are considered to induce water sorption of the photocured composite resin in a mouth, resulting in gradual long-term deterioration of aesthetics and mechanical properties of the composite resins. In this study, some additives such as light stabilizer and antioxidant were added to composite resins to promote durability and storage stability of the last product. First of all, color change increased as a light stabilizer. Tinuvin P, was added to the composed resins and color stability was improved as an antioxidant, Irganox 245, was added to ones. In addition, when Tinuvin P and Irganox 245 were added together to the composed resins. the color stability was enhanced and mechanical properties such as diametral tensile strength before and after acceleration tests were also not greatly decreased. Therefore, when 0.5 weight Percent of Tinuvin P and 0.1 weight percent of Irganox 245 were added together to dental composite resins. the durability and color stability were enhanced, and furthermore the storage stability was also improved for the composed resins.

• Journal of the korean academy of Pediatric Dentistry
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• 제27권3호
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• pp.388-393
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• 2000

Cleft lip and palate is one of the most common congenital defects in oro-maxillo-facial region. Because most patients undergo surgical repair in early life, the sagittal jaw relationships used to be deteriorated gradually from palate surgery up to adulthood. Also, the maxillary lateral incisor may be absent or atypical-shaped in the cleft site and may not erupt or erupt ectopically, so multidisciplinary dental cares are needed for cleft lip and palate patients. The effects of the cleft lip and alveolus seem to be limited to that part of the dentofacial complex that surrounds the cleft area. In the maxillary arch, the anterior part of the non cleft segment has a tendency to be rotated forward. On the other hand, the cleft segment has a tendency to rotated slightly medially ; hence, the tendency for canines to be edge-to-edge and sometimes in crossbite. Lip and alveolus surgery adequetely correct these problems, with little untoward effect on the skeletal maxillary-mandible relationships. In this report, the patient has a repaired lip and cleft alveolus on the left side with congenital missing on '62, '22, oronasal fistula, and skeletal class III malocclusion which is not affected by lip surgery. Dental treatments for this patient including orthodontic(space supervision, functional regulator in mixed dentition, fixed therapy in permanent dentition) and prosthodontic(removable obturator with key and keyway attachment and Konus crown) therapy were performed to improve the patient's functions and esthetics.

• Journal of the korean academy of Pediatric Dentistry
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• 제29권1호
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• pp.1-10
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• 2002

The purpose of this study was to evaluate the fluoride release and anticariogenic effect of two compomers which is known to have been developed to improve the weak properties of glass ionomer cement and composite resin. Z-100 as composite resin(Group I), Dyract AP(Group II) and F-2000(Group III) as compomer, and Fuji II LC as glass ionomer cement(Group IV) were used as test materials and evaluations were peformed by pH/ISE meter far analyses of fluoride and polarizing microscope for analyses of anticariogenicity. The results can be summarized as follows: 1. The amount of fluoride release in compoite resin and compomer groups showed general pattern of decline during test period. Z-100 showed no fluoride release during test period. Fuji II LC showed the highest fluoride release among test groups and then F-2000 were followed. 2. The least resistance to dimineralization was observed microscopically in Z-100 group which has no fluoride in it. The best resistance to dimineralization was observed microscopically in Fuji II LC group and then compomer groups were followed. 3. Significant difference in lesion area was found between Fuji II LC group and another groups. Significant difference in lesion area was found between compomer groups and Z-100 group. No significant difference in lesion area was found between Dyract AP group and F-2000 cup. 4. Two compomers showed continual fluoride release and anticariogenic effect around filling materials. therefore, compomer was evaluated very attractive restorative material in pediatric dentistry.

• Journal of the korean academy of Pediatric Dentistry
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• 제29권3호
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• pp.362-370
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• 2002

During the last two decades, many new filling materials and material groups have been developed. the number of available restoratives has increased dramatically, especially during the last 5 years. Ormocers are a new class of materials which are still under development with regard to dental applications. However, in the chemical literature these materials have been known for a long time and used for producing scratch resistant coatings on plastic spectacle lenses. It is a combination of inorganic and organic materials. 'Ormocer' is an abbreviation for 'Organically Modified Ceramics'. These compounds are also known in the literature as 'Ormosils' (organically modified silicates). Their chemistry is comparable to that of silicones and organic polymers. The purpose of this study was to determine of compressive strength and flexural strength of a ormocer (Admira) and to investigate the effects of water absorption in comparison with three composite resins(Z-100, Tetric Ceram, Surefil) and one compomer(Dyract AP). The following results were obtained ; 1. Admira had the lower compressive strength than Surefil, but no statistically difference with other materials at 1 day(p>0.05). 2. Admira had the lower flexural strength than all other materials at 1 day. From 2 days, Admits showed lower flexural strength than three composite resin(p<0.05). 3. There was not statistically significant difference of compressive and flexural strengths between hybrid composite resin group(Z-100, Tetric Ceram) and Packable resin group(Surefil) for experimental period(30 days)(p>0.05). 4. All five materials showed an increase in compressive and flexural strength till 2 days and showed a decrease from 7 days in water(p<0.05). 5. Each materials had the statistically similar behavior of compressive and flexural strengths over time(p>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• 제29권3호
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• pp.407-412
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• 2002

The primary cause of missing teeth vary depending on the region. The loss of posterior teeth is mainly due to dental caries, whereas that of the anterior teeth occur primarily due to trauma at the age of standing and walking and secondarily from the rampant dental caries. Particularly, reduction of the arch length in the cases of premature loss of primary teeth may compromise the eruption of succedaneous permanent teeth. This may result in crowding and impaction of the permanent teeth, and asymmetry of arch, thus a careful consideration for space maintenance should be made in such cases. Space maintainer is required in the case of premature loss of primary posterior teeth, because space loss result from the approximate and centrifugal movement of the neighboring teeth. Generally, in the case of primary incisor, space loss occurs when 1) tooth contact is relevant, 2) crowding in primary dentition is present, and 3) a primary incisor is lost before the eruption of primary canine. Contrarily, in the case of primary dentition with interdental space, space loss will not be observed, mostly when a primary incisor is lost after the eruption of primary canine. Thus, using a space maintainer in cases of premature loss of primary incisor has been introduced primarily not for the purpose of space maintaining but for an aesthetic purpose, prevention of parafunctional oral habits such as tongue thrust, and of pronunciation. Additionally, few case studies have been reported of space loss in cases of premature loss of primary incisor. This study is to report cases of the space loss following the premature loss of primary incisors observed in children.

• The Journal of Korean Academy of Prosthodontics
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• 제54권1호
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• pp.49-56
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• 2016

Excessive occlusal wear can result in unacceptable damage to the residual teeth structure, anterior guidance and masticatory function. An 86-year-old man presented with worn dentition and anterior deep bite due to loss of the posterior support. Two implants covered by Korean national health insurance, fixed partial denture and direct composite resin were used to restore the dentition, instead of removable prosthesis. The occlusal vertical dimension was increased by 2 mm in the premolar area and shortened dental arch concept was applied. This treatment was a less expensive alternative to full-mouth rehabilitation with positive esthetic and functional outcomes after 7 months of follow-up.

• The Journal of Korean Academy of Prosthodontics
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• 제54권1호
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• pp.41-48
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• 2016

Edentulous patients with severe alveolar bone resorption have trouble with using traditional complete denture. In order to overcome these problems, implant-retained overdenture was developed. SFI-bar$^{(R)}$ system can save time and cost compared to other existing bar systems which need complicated laboratory procedures because it can be adjusted directly in a patient's mouth. A 55-year-old male, who had experienced a fractured lower old implant-retained overdenture, wanted a durable and painless denture. The fractured Locator$^{(R)}$ attachments were removed and edentulous mandible was restored with SFI-bar$^{(R)}$. A 77-year-old female with a medical history of the Parkinson's disease and severely absorbed alveolar bone of mandible, wanted to wear a retentive mandibular denture without pain. After placing two implants in front of mental foramen, two adaptors were connected to two implants and a tube bar was connected to the adaptors. A female part fitted to the bar was attached to the new denture. These clinical reports describe two-implant-retained overdenture using the SFI-bar$^{(R)}$ system in mandibular edentulous patients. Since the patients were satisfied esthetically and functionally during 2 years' observation, we would like to report cases.

• Journal of the korean academy of Pediatric Dentistry
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• 제28권4호
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• pp.654-660
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• 2001

Dentinogenesis imperfecta is an example of an inheritable dentinal defect originating during the histodifferentiation stage of tooth development, with involvement of the primary and permanent teeth. Shields, Bixler and El-Kafrawy proposed three types of Dentinogenesis imperfecta : Type I, II, III. Witkop reported a prevalence of 1 in 8000 with the trait, and no significant difference between male and female. Affected teeth have red-brown discoloration often with distinctive wearness of occlusal surface of posterior teeth and incisal surface of anterior teeth. Once enamel seperated from underlying defective dentin, the dentin demonstrates significantly acclerated attrision. Radiographically, the teeth have thin roots, bulbous crown, cervical constriction, and obliteration of the root canals and pulp chambers. In primary dentition periapical lesions or multiple root fractures are often observed. In successive generations the phenotypes of discoloration and wearness of teeth occurred, and one of the patient's subships, 10 year-old sister, showed general discoloration of her teeth and mild wearness. In this case, a 4 year-old male reported to the Yonsei University Pedodontics clinic, with a chief complaint of discolored teeth. The teeth showed generally yellowish-brown discoloration and moderate wearness. In radiographic features, obliteration of pulp, bulbous crown, and short roots were observed. It was diagnosed as Dentinogenesis imperfecta. The posterior teeth were restored with Stainless Steel Crown, and defective incisors including left upper primary central incisor which was extracted due to a root fracture with Open-faced Stainless Steel crown.

• Journal of Dental Rehabilitation and Applied Science
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• 제37권2호
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• pp.61-72
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• 2021

A beautiful smile is made when it is symmetrical and gums are displayed less than 2 - 3 mm. Excessive gingival display also known as "gummy smile" is often recognized to be unaesthetic. Causes of gummy smile can be caused by delayed eruption, vertical maxillary excess, hypermobile upper lip, or a short upper lip. Meanwhile botulinum toxin which is an exotoxin produced from Clostridium botulinum, works by blocking the release of acetylcholine from the cholinergic nerve end plates leading to inactivity of the muscles. The application site and weakens the muscle tone is drawing attention as a gummy smile treatment caused by hypermobile upper lip. There have been many studies about the method of injecting botulinum toxin into muscles around the lips, but there is still no standardized research method and treatment method, so there is controversy over the therapeutic effect. The aim of this study is to review the previous studies about the predictors of indication and effects of gummy smile treatment using botulinum toxin injection. Especially we tried to propose a protocol for optimal dose and efficient injection point through the anatomical considerations for gummy smile treatment using botulinum toxin.

• The Journal of Korean Academy of Prosthodontics
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• 제46권5호
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• pp.470-478
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• 2008

Statement of problem: Use of all-ceramic prostheses fabricated with CAD/CAM systems is increasing in the dentistry. Marginal fidelity in production of all-ceramic restoration has important clinical implications and is a key consideration issue in CAD/CAM production as well. Purpose: The objective of this study was to analyse marginal fidelities of $Procera^{(R)}$ Allceram Crown. Material and methods: On 56 patients treated with $Procera^{(R)}$ system Allceram Crown at Dankook Dental Hospital, marginal discrepancies of 101 abutments were measured by stereomicroscope at coping and final restoration stages. Paired t-test and one-way analysis of variance on marginal discrepancy data were conducted to determine the presence of significant differences between measurement and measuring point stages. Results: Marginal discrepancies of final restoration ($45.82{\pm}30.84\;{\mu}m$) were lower than alumina coping ($53.84{\pm}38.83\;{\mu}m$). Furthermore, the differences were found to be statistically significant at 95% confidence level. Anterior marginal discrepancies were lower than posterior marginal discrepancies, but they were not statistically significant. Lingual marginal discrepancies were higher than other measurement sites, and the differences were found to be statistically significant at 95% confidence level. Conclusion: Within the conditions of this study, marginal fidelities of $Procera^{(R)}$ Allceram Crown were acceptable, and after porcelain build-up, marginal fitness improved over alumina coping. More careful scanning is needed for better results.