• 대한치과기공학회지
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• 제38권3호
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• pp.127-133
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• 2016

Purpose: Currently advanced in Dental CAD/CAM technology increase a use of Co-Cr sinter metal block at Dental CAD/CAM part traditionally it has been being used with metal casting method. There is an advantage that can leave out a step of investment and casting as well as reducing a working time to compare with conventional casting method in a dry milling. Methods: In this research, compare a deformation of before and after sinter result of Co-Cr sinter metal block. Design a specimen figure by 3D CAD software and transformed it to a STL file can be used at Dental CAD/CAM. With a transformed STL file, milled a Co-Cr sinter metal specimen by using a Dental CAD/CAM dry milling machine. It arrived at the following conclusions after measuring an outer form and thickness of a machined specimen and then after sinter measure it again in a way of before sinter measurement method. Results: It is confirmed that there is no error while a 3D design figure specimen is transformed to a Dental CAD data. It is observed that there is no error at Co-Cr sinter metal specimen which consider a length of single coping and bridge. Conclusion: It is observed that there is no deformation at a specimen of AS05 and AB05 are made of 0,5mm thickness. On the other hand, the out of range of deformation is observed at a specimen of AS10 and AB10 which are made of 1mm thickness.

• 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.

• 대한치과기공학회지
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• 제21권1호
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• pp.153-163
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• 1999

The 21st centurt, the era of change-space, is requesting us to readjust our education system. In other words, we should renew it by looking back into the past cultivate more advanced ideas. As a matter of fact junior colleges have been considered just as miniture of universities in every way such as curriculum, prossor emploment, school affairs, etc. Therefore we should change our existing education system not to be criticized for the next century. May students are trained for industry as dental technicians in our department of college. We should educate experiment and practice substantially as college professors as well as exert ourselves in developing our abilities to adapt to high diverse industrial technique, putting emphasis on practice more than theory. It is mecessary for us to sufficiently teach the technique to good students and make them display their abilities in order to produce high quality goods. Reinvestment ineducation is a condition precedent. Dental laboratories have just employed the students that graduated from our college. However it's time for a change. They should pay attention to our education and assist us in all respects with the thought of equally educating professional dental technicians together with us. The field practice system is subject to reinforcement so that our students have more opporunities of utilizing the tools and materials for practice. Finally we should not only carry out new reserch more deeply no less than dental technicians who are experienced in business for development of education system but endeavor to meet pratical education by adding what is pratically needed in dental laboratories to the existing education system.

• 대한치과기공학회지
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• 제36권4호
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• pp.247-253
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• 2014

Purpose: The aim of this study was to evaluate the effect of colored zirconia with different coloring liquids. Methods: Total 30 specimens were prepared. Specimens were classified into 6 groups: IPS e.max Ceram(P), Uncolored zirconia(C), VITA In-Ceram$^{(R)}$2000 YZ LL1(L), Zirkonzahn coloring liquid(Z), Wieland coloring liquid(W), and Kuwotech coloring liquid(K). Four different types of zirconia coloring liquid, VITA In-Ceram$^{(R)}$ 2000 YZ LL1(VITA Zahnfabrik, Germany), Zirkonzahn coloring liquid(Zirkonzahn, Italy), Wieland coloring liquid(Wieland, Germany), Kuwotech coloring liquid(Kuwotech, Korea) were used to fabricate colored zirconia by using infiltrating method and then completely sintered. The color of the all specimens was measured using the spectrophotometer(CM-2600d, Konica Minolta, Japan) and expressed in terms of the 3-coordinated values(CIE $L^*a^*b^*$). Color differences were calculated using the equation $${\Delta}E^*=[({\Delta}L^*)^2+({\Delta}a^*)^2+({\Delta}b^*)^2]^{1/2}$$. Results: $L^*a^*b^*$ values of the colored zirconia were affected by the coloring liquids. The uncolored zirconia(C) group showed the highest $L^*$ value and zirkonzahn coloring liquid(Z) group showed the lowest $L^*$ value. Zirkonzahn coloring liquid(Z) showed the highest $a^*$ value and VITA In-Ceram 2000 YZ LL1(L) group showed the highest $b^*$ value. Generally, the color difference(${\Delta}E^*$) in all groups showed higher than 3.7 except between IPS e.max Ceram(P) and wieland coloring liquid(W) group. Conclusion: Within the limitations of this study, various coloring liquids influenced the $L^*$, $a^*$, and $b^*$ values of colored zirconia. IPS e.max Ceram(P) and wieland coloring liquid(W) group did not show clinically perceiving color difference.

• The Journal of Advanced Prosthodontics
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• 제1권1호
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• pp.31-36
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• 2009

PURPOSE. To determine the change in stability of single-stage, three different design of implant systems in humans utilizing resonance frequency analysis for early healing period(24 weeks), without loading. MATERIAL AND METHODS. Twenty-five patients were included into this study. A total of 45 implants, three different design of implant systems(group A,C,R) were placed in the posterior maxilla or mandible. The specific transducer for each implant system was used. ISQ(implant stability quotient) reading were obtained for each implant at the time of surgery, 3, 6, 8, 10, 12, 24 weeks postoperatively. Data were analyzed for different implant type, bone type, healing time, anatomical locations. RESULTS. For each implant system, a two-factor mixed-model ANOVA demonstrated that a significant effect on ISQ values(group A=0.0022, C=0.017, R=0.0018). For each implant system, in a two-factor mixed model ANOVA, and two-sample t-test, the main effect of jaw position(P > .005) on ISQ values were not significant. CONCLUSIONS. All the implant groups A, C and R, the change patterns of ISQ over time differed by bone type. Implant stability increased greatly between week 0 and week six and showed slow increase between week six and six months(plateau effect).

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.93-97
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• 2015

PURPOSE. Xerostomia can diminish the quality of life, leads to changes in normal chemical composition of saliva and oral microbiata, and increases the risk for opportunistic infections, such as Candida albicans. Various artificial salivas have been considered for patients with xerostomia. However, the knowledge on the antifungal and antiadhesive activity of artificial saliva substitutes is limited. The aim of the present study was to evaluate influence of two artificial salivas on the adhesion of Candida albicans to the polymethylmethacrylate disc specimens. MATERIALS AND METHODS. Two commercial artificial salivas (Saliva Orthana and Biotene Oral Balance Gel) were selected. 45 polymethylmethacrylate disc specimens were prepared and randomly allocated into 3 groups; Saliva Orthana, Biotene-Oral Balance gel and distilled water. Specimens were stored in the artificial saliva or in the sterile distilled water for 60 minutes at $37^{\circ}C$. Then they were exposed to yeast suspensions including Candida albicans. Yeast cells were counted using ${\times}40$ magnification under a light microscope and data were analysed. RESULTS. Analysis of data indicated statistically significant difference in adhesion of Candida albicans among all experimental groups (P=.000). Findings indicated that Saliva Orthana had higher adhesion scores than the Biotene Oral Balance gel and distilled water (P<.05). CONCLUSION. In comparison of Saliva Orthana, the use of Biotene Oral Balance Gel including lysozyme, lactoferrin and peroxidase may be an appropriate treatment method to prevent of adhesion of Candida albicans and related infections in patients with xerostomia.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.146-150
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• 2015

PURPOSE. This in vitro study aimed to compare the failure load and failure characteristics of two different zirconia framework designs of premolar crowns when subjected to static loading. MATERIALS AND METHODS. Two types of zirconia frameworks, conventional 0.5 mm even thickness framework design (EV) and 0.8 mm cutback of full contour crown anatomy design (CB), were made for 10 samples each. The veneer porcelain was added on under polycarbonate shell crown made by vacuum of full contour crown to obtain the same total thickness of the experiment crowns. The crowns were cemented onto the Cobalt-Chromium die. The dies were tilted 45 degrees from the vertical plane to obtain the shear force to the cusp when loading. All crowns were loaded at the lingual incline of the buccal cusp until fracture using a universal testing machine with cross-head speed 0.5 mm/min. The load to fracture values (N) was recorded and statistically analyzed by independent sample t-test. RESULTS. The mean and standard deviations of the failure load were $1,170.1{\pm}90.9$ N for EV design and $1,450.4{\pm}175.7$ N for CB design. A significant difference in the compressive failure load was found (P<.05). For the failure characteristic, the EV design was found only cohesive failures within veneering porcelain, while the CB design found more failures through the zirconia framework (8 from 10 samples). CONCLUSION. There was a significant difference in the failure load between two designs, and the design of the framework influences failure characteristic of zirconia crown.

• The Journal of Advanced Prosthodontics
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• 제4권4호
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• pp.204-209
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• 2012

PURPOSE. The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS. A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS. Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION. The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants.

• The Journal of Advanced Prosthodontics
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• 제4권4호
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• pp.197-203
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• 2012

PURPOSE. The aim of this systematic review was to address treatment outcome according to attachment systems for mandibular implant overdentures in terms of implant survival rate, prosthetic maintenance and complications, and patient satisfaction. MATERIALS AND METHODS. A systematic literature search was conducted using PubMed and hand searching of relevant journals considering inclusion and exclusion criteria. Clinical trial studies on mandibular implant overdentures until August, 2010 were selected if more than one type of overdenture attachment was reported. Twenty four studies from 1098 studies were finally included and the data on implant survival rate, prosthetic maintenance and complications, patient satisfaction were analyzed relative to attachment systems. RESULTS. Four studies presented implant survival rates (95.8 - 97.5% for bar, 96.2 - 100% for ball, 91.7% for magnet) according to attachment system. Ten other studies presented an implant survival rate ranging from 93.3% to 100% without respect to the attachment groups. Common prosthetic maintenance and complications were replacement of an assay for magnet attachments, and activation of a matrix or clip for ball or bar attachments. Prosthetic maintenance and complications most commonly occurred in the magnet groups. Conflicting findings were found on the rate of prosthetic maintenance and complications comparing ball and bar attachments. Most studies showed no significant differences in patient satisfaction depending upon attachment systems. CONCLUSION. The implant survival rate of mandibular overdentures seemed to be high regardless attachment systems. The prosthetic maintenance and complications may be influenced by attachment systems. However patient satisfaction may be independent of the attachment system.

• The Journal of Advanced Prosthodontics
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• 제4권4호
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• pp.179-186
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• 2012

PURPOSE. The aim of this study was to evaluate the efficiency of manual polishing over autoglazed and overglazed porcelain and their effect on plaque accumulation. MATERIALS AND METHODS. Thirty-six porcelain discs were fabricated out of which 18 each was subjected for autoglazing and overglazing. Half surface of the discs was left intact; the remaining half was roughened with medium grit diamond bur. Roughened surfaces were repolished by porcelain polishing kits (Shofu, DFS, Eve). All the surfaces were evaluated by the perthometer and SEM. Six discs from each sample were placed in human volunteer's mouth for 72 hours to evaluate the plaque accumulation. Acquired data was subjected to ANOVA comparative evaluation. RESULTS. Roughened surfaces had average roughness value of $2.88{\pm}0.1935{\mu}m$. The repolished surfaces by porcelain correction kits Shofu, DFS and Eve, average roughness value reduced to $0.6250{\pm}0.1036$, $0.9192{\pm}0.0953$, $0.9017{\pm}0.1305$ respectively. Autoglazed and overglazed surfaces showed the mean roughness value (Ra) of $0.4217{\pm}0.0685$, $0.3450{\pm}0.0729$. SEM study showed the improved surfaces when subjected for polishing. Plaque accumulation percentage was the highest on roughened surface ($93.83{\pm}6.2552%$), followed by porcelain discs polished by commercial kits. Autoglazed surfaces found to be the best surfaces with the least plaque accumulation ($0.5237{\pm}0.4209%$). CONCLUSION. All the polishing kits used in the study reduced the average roughness by approximately 77%. Corrected porcelain surfaces should ideally be reglazed, alternatively, polish the surfaces before final cementation.