• Restorative Dentistry and Endodontics
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• 제41권1호
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• pp.22-28
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• 2016

Objectives: The goal of this study was to compare the density of gutta-percha root fillings obturated with the following techniques: cold lateral (CL) compaction, ultrasonic lateral (UL) compaction, and warm vertical (WV) compaction. Materials and Methods: Thirty-three extracted mandibular first molars, with two separate mesial canals in each, were selected. After instrumentation, the canals were stratified into three groups based on canal length and curvature, and underwent obturation with one of the techniques. No sealer was used in order to avoid masking any voids. The teeth were imaged pre- and post-obturation using micro-computed tomography. The reconstructed three-dimensional images were analyzed volumetrically to determine the amount of gutta-percha present in every 2 mm segment of the canal. P values < 0.05 were considered to indicate statistical significance. Results: The overall mean volume fraction of gutta-percha was $68.51{\pm}6.75%$ for CL, $86.56{\pm}5.00%$ for UL, and $88.91{\pm}5.16%$ for WV. Significant differences were found between CL and UL and between CL and WV (p < 0.05), but not between UL and WV (p = 0.526). The gutta-percha density of the roots treated with WV and UL increased towards the coronal aspect, but this trend was not noted in the CL group. Conclusions: WV compaction and UL compaction produced a significantly denser gutta-percha root filling than CL compaction. The density of gutta-percha was observed to increase towards the coronal aspect when the former two techniques were used.

• Journal of Periodontal and Implant Science
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• 제40권4호
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• pp.164-171
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• 2010

Purpose: This study compared the total antioxidant status (TAS) and superoxide dismutase (SOD) activity in the saliva of periodontally compromised patients before and after scaling and root planing (SRP) to assess their diagnostic utility. Methods: Severe chronic periodontitis patient (test group) and subjects with no attachment loss, sites showing a 3 mm or more probing depth and a sulcus bleeding index < 10% (control group) were enrolled in this study. Saliva sampling and clinical examination were performed at one week, one month and 3 months after SRP. The TAS and SOD activity in each patient's saliva was measured for the comparative analysis between the groups. Results: In the test group, the TAS decreased directly after SRP. With time, it increased slightly and was relatively unchanged compared to the baseline. In the control group, the TAS also decreased immediately after SRP but increased gradually with time until 3 months. The SOD activity in the test and control subjects decreased immediately after SRP until 1 month. At 3 months, the SOD activity had increased. Both groups had a similar profile of SOD activity. However, the SOD activity of the control group was significantly higher than that of the test group at each point in time (P < 0.05). Conclusions: There was a significant difference in the total salivary antioxidant level between the periodontitis and healthy or gingivitis (control) group during the experiment period. The total antioxidant level in the saliva was higher in the patients with severe chronic periodontitis than the healthy or gingivitis control before SRP. The SOD activity of the periodontitis patients was lower than the control at each time point. These findings conclusively reveal the possible use of saliva as a diagnostic tool for periodontal health.

• The Journal of Advanced Prosthodontics
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• 제8권6호
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• pp.417-422
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• 2016

PURPOSE. The purposes of this study were to evaluate the staining resistance of CAD/CAM resin-ceramics polished with different techniques and to determine the effectiveness of the polishing techniques on resin-ceramics, comparing it with that of a glazed glass-ceramic. MATERIALS AND METHODS. Four different CAD/CAM ceramics (feldspathic ceramic: C-CEREC Blocs, (SIRONA) and three resin-ceramics: L-Lava Ultimate, (3M ESPE), E-Enamic, (VITA) and CS-CeraSmart, (GC)) and one light cure composite resin: ME-Clearfil Majesty Esthetic (Kuraray) were used. Only C samples were glazed (gl). Other restorations were divided into four groups according to the polishing technique: nonpolished control group (c), a group polished with light cure liquid polish (Biscover LV BISCO) (bb), a group polished with ceramic polishing kit (Diapol, EVE) (cd), and a group polished with composite polishing kit (Clearfil Twist Dia, Kuraray) (kc). Glazed C samples and the polished samples were further divided into four subgroups and immersed into different solutions: distilled water, tea, coffee, and fermented black carrot juice. Eight samples ($8{\times}8{\times}1mm$) were prepared for each subgroup. According to CIELab system, four color measurements were made: before immersion, immersion after 1 day, after 1 week, and after 1 month. Data were analyzed with repeated measures of ANOVA (${\alpha}=.05$). RESULTS. The highest staining resistance was found in gl samples. There was no difference among gl, kc and cd (P>.05). Staining resistance of gl was significantly higher than that of bb (P<.05). Staining resistances of E and CS were significantly higher than those of L and ME (P<.05). CONCLUSION. Ceramic and composite polishing kits can be used for resin ceramics as a counterpart of glazing procedure used for full ceramic materials. Liquid polish has limited indications for resin ceramics.

• 디지털융복합연구
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• 제14권1호
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• pp.321-326
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• 2016

치주질환은 치아주위 조직에 발현된 염증성 질환이다. 전염증성 사이토카인인 $TNF-{\alpha}$는 국소적인 염증이나 전반적인 염증과 관련이 있는 것으로 알려져 있다. 본 연구의 목적은 한국인에서 TNF 유전자 다형성과 전반적 급진성 치주염 간의 관계를 알아보고자 하였다. 연구대상은 실험군이 60명, 대조군이 81명 이었다. 협측에서 DNA를 채취하여 각 제한효소를 이용한 PCR-RFLP에 의해 $TNF-{\alpha}-308$과 -238을 측정하였다. 급진성 치주염 환자에서 $TNF-{\alpha}-308$ 유전자형은 A/A 3.2%, A/G 38.7% 그리고 G/G 82.35%가 나타났으며 대조군에서는 각 9.1%, 45.5%, 45.5%로 유의한 차이를 보이는 결과이다. $TNF-{\alpha}-238$의 대립유전자 2의 빈도는 실험군에서 67.6%, 대조군에서 72.2%로 유의한 차이를 보였다. 이러한 결과에 따르면 $TNF-{\alpha}-308$과 -238의 유전자다변성은 한국인의 급진성치주염과 연관이 있을 것으로 생각된다.

• 디지털융복합연구
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• 제13권7호
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• pp.283-292
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• 2015

본 연구는 의료기관인증제도 도입에 따른 환자안전과 의료서비스의 질이 병원경영활동에 미치는 복합영향을 확인하고 조직문화의 매개효과를 파악하고자 하였다. 이를 위해, 2014년 6월말까지 의료기관인증을 획득한 대구 경북지역에 위치하는 300병상 미만과 300병상 이상, 6개 의료기관 종사자를 대상으로 2014년 9월 22일부터 4주간 설문조사 하였다. 해당 병원에서 1년 이상 근무한 377명을 연구대상으로 하였다. 연구결과, 300병상 미만 중소병원과 300병상 이상 병원 및 종합병원 모두, 환자안전과 의료의 질, 조직문화와 병원경영활동은 변수 간 정(+)의 상관관계가 있는 것으로 나타났다. 환자안전과 의료의 질, 병원경영활동 사이에 조직문화가 부분 매개효과가 있는 것으로 나타났으며 인과효과가 높았다. 따라서 의료기관인증제도 도입에 따른 환자안전과 의료의 질 향상 활동은 병원경영활동을 증진시키는데 효과가 있다 여겨진다.

• 생명과학회지
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• 제20권3호
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• pp.321-325
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• 2010

구강에 상주하는 미생물 중, Streptococcus mutans는 충치 및 치주염의 원인인 치아플라그를 형성하는데 중요한 역할을 한다. Phytochemical은 식물에서 추출된 화학성분으로서, 사람의 건강에 유익한 영양물질로서 많은 연구들이 진행되어왔다. 본 연구는 이 phytochemical이 중요 구강미생물인 S. mutans에 대한 효과를 살펴보았다. 최근에 Thomson seedless raisin에서 여러 phytochemicals가 추출되었는데, 그 중 oleanolic acid (OA)와 5-(hydroxymethyl)-2-furfural (HF)의 임상적으로 중요한 여러 미생물에 대한 항균활성효과를 확인한 결과, OA가 그람음성균들에게는 항균활성효과가 나타나지 않았고, 그람양성균들에만 항균활성효과를 보였다. 그러나, HF의 경우에는 모든 균주에 대해 항균활성을 나타내지 않았다. 또한, OA는 S. mutans 균주의 표면부착과 생균막의 형성을 저해하기도 하였다. 따라서, 이 연구결과들은 OA가 치아에 존재하는 S. mutans의 생육 및 여러 생리적 특성들을 저해하므로 항플라그제나 항충치약으로서의 활용가능성을 확인할 수 있었다.

• 한국분말재료학회지
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• 제11권5호
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• pp.412-420
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• 2004

The purpose of the present study is to determine an optimum composition using cheaper powders keeping with high performance of hard rock cutting diamond saw blade. With 50Fe-20(Cu . Sn)-30Co specimen, a part of Co was replaced by Ni(5%, 10%, and 15%, respectively). These specimens were hot pressed and sintered for predetermined time at various temperature. Sintering is performed by two different methods of temperature controlled method and specimen dimension controlled method. In order to determine the property of the sintered diamond saw blade, 3 point bending tester, X-ray diffractometer, and SEM were used. As the Co in the bond alloy was replaced by Ni, the hardness of the specimen increased. Thus the 50Fe-20(CuㆍSn)-15Co-15Ni specimen showed the maximum hardness of 104(HRB). The results of 3 point bending test showed that flexure strength decreased along with increase in Ni content. This is attributed to the formation of intermetallic compound(Ni$_{x}$Sn) determined by X-ray diffraction. The fracture surface after 3 point bending test showed that diamond was fractured in the specimen containing 0%, 5%, and 10%Ni, and the fracture occurred at the interface between diamond and matrix in the specimen containing 15%Ni. The cutting ability test showed that the abrasive property was not changed in the specimen containing 0%, 5%, and 10%Ni. The optimum composition determined in this study is 50Fe-20(CuㆍSn)-20Co-10Ni.

• 대한치과교정학회지
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• 제46권5호
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• pp.290-300
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• 2016

Objective: This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods: Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results: An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions: The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization.

• International Journal of Oral Biology
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• 제41권3호
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• pp.105-111
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• 2016

${\beta}-carotene$ is present in carrots, pumpkins, and sweet potatoes. It suppresses many types of cancers by regulating cellular proliferation and apoptosis through a variety of mechanisms. However, the effects of ${\beta}-carotene$ on oral cancer cells have not been clearly established. The main goal of this study was to investigate the effects of ${\beta}-carotene$ on cell growth and apoptosis in oral cancer cells. Our results demonstrate that treatment with ${\beta}-carotene$ induced inhibition of cell growth, and that the effect was dependent on ${\beta}-carotene$ treatment time and concentration in KB cells. Furthermore, treatment with ${\beta}-carotene$ induced nuclear condensation and fragmentation in KB cells. ${\beta}-carotene$ promoted proteolytic cleavage of procaspase-3, -7, -8 and -9 with associated increases in the concentration of cleaved caspase-3, -7, -8 and -9. In addition, the level of cleaved PARP was increased by ${\beta}-carotene$ treatment in KB cells. These results suggest that ${\beta}-carotene$ can suppress cell growth and induce apoptosis in KB human oral cancer cells, and that it may have potential usefulness in anti-cancer drug discovery efforts.

• International Journal of Oral Biology
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• 제45권1호
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• pp.25-31
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• 2020

Enamel knot (EK)-a signaling center-refers to a transient morphological structure comprising epithelial tissue. EK is believed to regulate tooth development in early organogenesis without its own cellular alterations, including proliferation and differentiation. EKs show a very simple but conserved structure and share functions with teeth of recently evolved vertebrates, suggesting conserved signaling in certain organs, such as functional teeth, through the course of evolution. In this study, we examined the expression patterns of key EK-specific genes including Dusp26, Fat4, Meis2, Sln, and Zpld1 during mice embryogenesis. Expression patterns of these genes may reveal putative differentiation mechanisms underlying tooth morphogenesis.