• Imaging Science in Dentistry
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• 제43권1호
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• pp.17-23
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• 2013

Purpose: The purpose of this study was to assess cone-beam computed (CBCT) sialography imaging in the detection of different changes associated with lesions of salivary glands. Materials and Methods: This study consisted of 8 cases with signs and symptoms from salivary gland lesions. Conventional sialography using digital panoramic and lateral oblique radiographs and CBCT sialography were performed for each subject. The radiographs were evaluated by 3 radiologists independently of each other. The results were compared between conventional sialography and CBCT sialography in the evaluation of various lesions associated with the salivary glands. Results: There was an agreement between the radiologists in interpreting the lesions that affected salivary glands with both techniques. The detection of the presence of stones or filling defects, stenosis, ductal evagination, dilatation, and space occupying lesions was 83% for conventional sialography compared with CBCT sialography. CBCT sialography was superior to conventional sialography in revealing stones, stenosis, and strictures, especially in the second and third order branches. Conclusion: It would be advisable to perform CBCT sialography in cases of obstructive salivary gland diseases for better demonstration of the ductal system of the gland.

• Journal of Korean Dental Science
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• 제14권2호
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• pp.61-68
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• 2021

Purpose: The aim of this study was to investigate the outcomes of endodontic treatment of mandibular second molar with C-shaped canal in elderly patients and related factors affecting the survival of the tooth. Materials and Methods: From 2010 to 2015, the survival rate following endodontic treatment was evaluated in elderly patients over 60 years who visited the Veterans Health Service Medical Center for endodontic treatment. The presence of C-shaped canals was confirmed using clinical records and radiographic features. Patient's age, sex, systemic diseases, tooth location, vitality, signs and symptoms, fractures, caries, apical radiolucency, canal shaping methods, sealer leakage, filling voids, and restoration of prosthesis were included in the analyses as confounding variables. The survival rate of teeth was analyzed using Kaplan-Meire analysis and the relationship between the survival rate and variables was analyzed using Simple and Multiple Cox regression analysis. Result: In total, 107 teeth in elderly patients had C-shaped canal. The survival rate of teeth that received endodontic treatment was 63.70%. None of the factors investigated significantly influenced the survival rate (P>0.05). Conclusion: In elderly patients with C-shaped canal, the survival rate after root canal treatment was not significantly different from that of other mandibular molars.

• Restorative Dentistry and Endodontics
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• 제46권3호
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• pp.38.1-38.13
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• 2021

The elimination of endodontic biofilms and the maintenance of a leak-proof canal filling are key aspects of successful root canal treatment. Several materials have been introduced to treat endodontic disease, although treatment success is limited by the features of the biomaterials used. Silver nanoparticles (AgNPs) have been increasingly considered in dental applications, especially endodontics, due to their high antimicrobial activity. For the present study, an electronic search was conducted using MEDLINE (PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar, and EMBASE. This review provides insights into the unique characteristics of AgNPs, including their chemical, physical, and antimicrobial properties; limitations; and potential uses. Various studies involving different application methods of AgNPs were carefully examined. Based on previous clinical studies, the synthesis, means of obtaining, usage conditions, and potential cytotoxicity of AgNPs were evaluated. The findings indicate that AgNPs are effective antimicrobial agents for the elimination of endodontic biofilms.

• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.57-66
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• 1990

The author conducted a dental survey of college girl students and compared with that of college students 20 years and 10 years ago which based on the same criteria. The items of this survey included the prevalence of dental caries, DMFT and the kinds of restored materials. College girl students 2,294 were examined in May 1988, with the recommended criteria and method of W.H.O.. Among them, the data of 2,243 were analyzed and compared with the data of 1968 and 1978. The following results were obtained : 1. The average number of present teeth was $28.86{\pm}1.65$, which does not show much difference when compared to $29.00{\pm}1.94$ of 1968 and $28.97{\pm}1.64$ of 1978. 2. The prevalence of dental caries was 86.22%, which increased in comparison to 83.25% of 1968 and 84.92% of 1978. 3. DMF index was 19.98, which considerably increased in comparison to 14.56 of 1968 and 15.51 of 1978. 4. The number of DMFT was $5.75{\pm}5.04$ per student. Compared to $4.23{\pm}3.88$ of 1968 and $4.49{\pm}3.69$ of 1978, there is a considerable increase. I) The average number of decayed(D) teeth was $1.14{\pm}1.63$, which decreased from $1.16{\pm}1.57$ of 1968 and $2.09{\pm}2.16$ of 1978. II) The average number of missing(M) teeth was $0.23{\pm}0.73$, which also decreased from $0.69{\pm}1.11$ of 1968 and $0.32{\pm}0.79$ of 1978. III) The average number of filled(F) teeth was $4.39{\pm}4.91$, which increased from $2.38{\pm}3.33$ of 1968 and $2.09{\pm}3.17$ of 1978. 5. According to the analysis of filling material, filling baby including amalgam, gold inlay, resin, silicate cement and paladium inlay was 90.5%, which increased in comparison to 72.8% of 1968 and 83.6% of 1978. Among them, amalgam occupied 62.93%, which showed the most increase. On the other hand, crown and bridge was 6.5%, 3.0%, respectively, which showed continuous decrease from 12.1%, 15.1% of 1968 and 8.7%, 7.7% of 1978. Therefore, the prosthodontic treatment reduced due to the decrease of tooth extraction. In contrast, there is continuous increase of conservative treatment which maintaining natural tooth.

• 치위생과학회지
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• 제21권4호
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• pp.243-250
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• 2021

Background: Endodontic sealers or their toxic components may become inflamed and lead to delayed wound healing when in direct contact with periapical tissues over an extended period. Moreover, an overfilled sealer can directly interact with adjacent tissues and may cause immediate necrosis or further resorption. Therefore, the treatment outcome conceivably depends on the endodontic sealer's biocompatibility and osteogenic potential. This study aimed to evaluate the cell viability and osteogenic effects of four different sealers in osteoblastic cells. Methods: AH Plus (resin-based sealer), Pulp Canal Sealer EWT (zinc oxide-eugenol sealer), BioRoot RCS (calcium silicate-based sealer), and Well-Root ST (MTA-based calcium silicate sealer) were mixed strictly according to the manufacturer's instructions, and dilutions of sealer extracts (1/2, 1/5 and 1/10) were determined. Cell viability was measured using the water-soluble tetrazolium-8 (WST-8) assay. Differentiation was assessed by alkaline phosphatase (ALP) activity and mineralized nodule formation by Alizarin Red S staining. Results: The cell viability of the extracts derived from the sealers excluding Well-Root ST was concentration dependent, with sealer extracts having the least viability at a 1/2 dilution. At sealer extract dilution of 1/10, the test groups showed the same survival rate as that control group, with the exception of BioRoot RCS. Among all experimental groups, BioRoot RCS showed the highest cell viability after 48 hours. The ALP activity was significantly higher in a concentration-dependent manner. Furthemore, all four materials promoted ALP activity and mineralized nodule formation compared to the control at 1/10 dilutions. Conclusion: This is the first study to highlight the differences in biological activity of these four materials. These results suggest that the composition of root canal sealers appears to alter the form of biocompatibility and osteoblastic differentiation.

• Restorative Dentistry and Endodontics
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• 제6권1호
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• pp.109-114
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• 1980

Ease of manipulation, adequate mechanical properties, long years of experience and economical cost are the factors which have established amalgam as the most widely used material for dental restorations. But amalgam restoration may require replacement because of secondary caries, fracture, "fall-out", dimensional change, tarnish or corrosion etc.. These failures of amalgam restorations seem to arise from failures during operations rather than from the inherent shortcomings of the material itself or of the patient's mismanagement. It is anticipated that notonly number of analgam restoration, but failures will be increase after more extensive utilization of the medical insurance which began in 1977. Then authors think that it would be helpful for the development of better treatment in daily dental practice, to know the duration of amalgam restorations and the reasons for their replacement. The data for this survey was compiled from 2, 856 out-patients of the Department of Dentistry, Ewha Woman's University Hospital from January 1975 to December 1977. 260 cases among 1,718 fillings were studied, of which 205 cases both had a single reason for replacement and recognized the date of the previous filling. The results obtained were as follows; 1. Amalgam fillings were 58. 5 percent of all dental restorative materials. Of these, 15. 13 percent of the amalgam restorations had to be replaced. 2. The first reason for replacement of amalgam restorations was secondary caries (56.10%), the second was fracture (23.80%) and the third was "fall-out" (8.78%). 3. Among those amalgms requiring replacement, 52.2 percent had been in place less than 3 years, 70.7 percent within 5 years and 89.8 percent had been in place less than 10 years. Only 10.2 percent had been in place more than 10 years.

• 한국재료학회지
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• 제19권7호
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• pp.403-406
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• 2009

The friction characteristics of automotive brake friction materials that contained different ceramic content were investigated. Several kinds of raw materials, such as resin-based binder, reinforcing fiber, friction restraint, abrasive, and filling materials were mixed, pressed, and heated in order to make the brake friction materials. The contents of SiC and $BaSO_4$ changed from 5 vol% to 20 vol%, respectively. In addition to this, the content of $Al_2O_3$ adjusted from 1 vol% to 16 vol%. The surface morphology of the SiC containing sample appeared rough while more debris was observed when the contents of SiC increased. This implies that the SiC containing brake composite was not adequate for the automobile. However, the relatively smooth surface was observed in samples that contained the $Al_2O_3$. But the roughness was low with a content of 11 vol% $Al_2O_3$ compared to the other samples. This is consistent with the abrasive properties of the samples. In the case of $BaSO_4$ containing samples, the smoothes surface was observed in the contents of 15 vol% $BaSO_4$. Thus, it was concluded that the 11 vol% $Al_2O_3$ and 15 vol% $BaSO_4$ containing composite would be the optimum content for the brake composite. Similar to the results of the surface morphology, the abrasion resistance consistently decreased when the content of SiC increased. On the contrary, the sample that contained 11 vol% $Al_2O_3$ and 15 vol% $BaSO_4$ showed the highest abrasion resistance compared to the other samples.

• 치위생과학회지
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• 제8권1호
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• pp.35-42
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• 2008

본 연구는 수도권, 서울, 전북지역의 치과위생사를 대상으로 2006년 7월부터 8월까지 실시한 656명에 대하여 자기 기입식 설문조사방식으로 치과위생사가 근무하는 병원환경에 대한 상태와 건강에 영향을 주는 요인, 치과위생사의 병원실내질환경 만족에 영향을 주는 환경요인 등에 차이점을 발견할 수 있는지를 파악하여 치과위생사의 건강관리를 위한 실내근무환경 개선과 신체자각증상 감소방안을 제시하고자 하였다. 1. 병원근무환경에 대한 주관적 평가를 통한 만족도를 분석한 결과 병원의 공기가 신선하다(2.51), 병원의 공기냄새가 기분 좋게 한다(2.71), 병원의 환기(2.84)로 실내공기질에 대한 만족도가 낮았다. 2. 자각증상경험정도에 대한 반응은 "등, 어깨, 목이 아프거나 뻣뻣하다"(3.50~3.67), "피곤하거나 졸리며 피로를 느낀다"(3.26~3.59)가 높게 나타났다. 3. 병원실내환경 만족도에 영향을 주는 요인은 병원 공기냄새가 가장 높게 나타나 실내공기질이 병원실내 환경 만족에 영향을 주는 주요한 요인이라는 결론을 얻었다. 그 외에도 병원 실내온도, 병원의 조명, 병원환기, 병원의 시끄러움, 병원공기 신선도 순으로 영향을 주었다. 4. 실내공기질에 따른 자각증상경험정도에 영향을 주는 요인은 "본인이 느끼는 건강상태"(p < 0.001), "화학물질 민감"(p < 0.001) 및 "냉난방 방식"(p < 0.001)순으로 나타났다. 5. 근무환경 만족도를 조사한 결과 실내공기질의 만족도가 가장 낮은 것으로 나타났으며, 이는 건물이 밀폐형이고 하루 환기횟수가 절대 부족하기 때문으로 파악되었다.

• Imaging Science in Dentistry
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• 제50권1호
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• pp.1-7
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• 2020

Purpose: This study was performed to evaluate the magnitude of artifacts produced by gutta-percha and metal posts on cone-beam computed tomography (CBCT) scans obtained with different tube currents and with or without metal artifact reduction (MAR). Materials and Methods: A tooth was inserted in a dry human mandible socket, and CBCT scans were acquired after root canal instrumentation, root canal filling, and metal post placement with various tube currents with and without MAR activation. The artifact magnitude was assessed by the standard deviation (SD) of gray values and the contrast-to-noise ratio (CNR) at the various distances from the tooth. Data were compared using multi-way analysis of variance. Results: At all distances, a current of 4 mA was associated with a higher SD and a lower CNR than 8 mA or 10 mA (P<0.05). For the metal posts without MAR, the artifact magnitude as assessed by SD was greatest at 1.5 cm or less (P<0.05). When MAR was applied, SD values for distances 1.5 cm or closer to the tooth were reduced (P<0.05). MAR usage did not influence the magnitude of artifacts in the control and gutta-percha groups(P>0.05). Conclusion: Increasing the tube current from 4 mA to 8 mA may reduce the magnitude of artifacts from metal posts. The magnitude of artifacts arising from metal posts was significantly higher at distances of 1.5 cm or less than at greater distances. MAR usage improved image quality near the metal post, but had no significant influence farther than 1.5 cm from the tooth.

• Restorative Dentistry and Endodontics
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• 제19권2호
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• pp.447-459
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• 1994

The purpose of this study is to evaluate of shear bond strength of light-curing composite resin to light-curing glass ionomer cement. Composite resin and glass ionomer cement have been widely used as an esthetic filling materials in dental clinics. To achieve better clinical results, sandwich technic was developed with conpensating for disadvantages of these two materials. Especially, light-curing glass ionomer cement provided greately improved bonding strength of teeth or composite resin, and then excellent clinical results can be acquired. In this study, 6 commercial light-curing glass ionomer cements(3 commercial restorative materials : Fuji II LC, Variglass VLC, Vitremer, and 3 commercial lining materials : Fuji Lining LC, Baseline VLC, Vitrebond) were devided two groups. According to manufacturer's appointment, no surface treatment was referred to N groups. Supposing. of clinical practice, surface grinding with water spray at 320 grit sand paper, 40 seconds etching with 37% phosphoric acid, 20 seconds washing, 20 seconds air drying was referred to N groups. Totally 12 experimental groups were devided, and all 120 specimens from 10 specimens of each groups were made. After light-curing composite resin was bonded to light-curing glass ionomer cement, shear bond strength was tested by Instron universal testing machine between glass ionomer cement and composit resin. The data were analyzed statistically by Student's t-test and ANOVA. The obtained results were as follows; 1. In light-curing glass ionomer cement, restorative materials showed higher shear bond strength to composite resin than lining materials(p<0.05). 2. Variglass VLC of restorative material group and Baseline VLC of lining material group have highest shear bond strength to composite resin(p<0.001). 3. In light-curing glass ionomer cement, surface grinding and acid etching reduced shear bond strength to composite resin(p<0.001)}. 4. VGN group 1s highest shear bond strength to composite resin, VBE group is lowest shear bond strength to composite resin(p<0.001).