• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.707-727
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• 2000

매식된 인공치아의 성공을 위해서는 적절한 교합과 수동적 적합성을 갖는 보철물의 제작과 구강내 노출 직후부터의 세균성 치태조절이 요구된다. 본 연구는 전처리(passivation과 tridodecyl - methyl - ammonium chloride(TDMAC) 처리)가 다른 타이타늄 표 면에 chlorhexidine varnish와 테트라사이클린 을 도포시 약제의 방출역학을 알아보고 구강내 치태형성의 억제정도를 평가하기 위하여 시행 되었다. 이를 위해 방출용액으로 인산완충액 성분의 인조타액을 1일${\sim}$1개월간 매일 교환하여 약제농도를 측정하고 타이타늄 박막에 잔류한 약제 활성을 측정하였으며 항균제 도포한 타이타늄 원판을 부착한 장치를 구강내 위치시킨 1일${\sim}$3주 후 원판을 제거하여 주사전자현미경으로 세균 부착상을 관찰하였다. 테트라사이클린은 TDMAC 처리된 표면에서 $10{\sim}18$일까지 유효농도로 방출되었고 표면의 유효 항균 활성은 $3{\sim}4$주간 유지되었으며, chlorhexidine varnish 도포 시에는 TDMAC 전처리시 초기에 $3{\sim}7$일 간 증가한 유효 항균 활성을 방출하여 매식지대치 등에 이러한 항균제도포 시 매식치 주위환경에 항균활성 공급원으로 작용할 수 있음을 보였다. 주사현미경적 관찰시 모든 타이타늄 표면에서 구강내 위치 30분 후에는 세균이 부착되어 있지 않고 타액 단백질 성분에서 유래한 것으로 보이는 피막물질이 표면을 부분 또는 전면에 걸쳐 덮고 있었다. 구강내 노출 2시간 후 항균제 미도포 표본들에는 약간의 구균이 단층으로, $1{\sim}3$일 후에는 부분적으로 두꺼운 세균층을 형성하였고 7일 후에는 표면전체에 걸쳐 세균층이 덮여있었으며 주로 구균과 약간의 간균이 주종을 이루었다. 항균제 도포시 구강내 노출 1주일 이전까지는 미도포군에 비해 치태형성이 지연되는 경향을 보였지만 2주 이후에는 세균 수나 치태형성 양상이 유사하였다. 이 연구로부터 항균제 도포시 1주일 이전의 초기 치태형성을 감소시킬 수 있음을 알 수 있었으며 이러한 연구결과는 타이타늄 임프란트 지대치 표면에 항균제의 도포가 임상적으로 유용할 수 있음을 시사하였다.

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.85-90
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• 2009

STATEMENT OF PROBLEM. Over the years, resin-bonded fixed partial dentures (RBFPDs) have gone through substantial development and refinement. Several studies examined the biomechanics of tooth preparation and framework design in relation to the success rate of RBFPDs and considered retention and resistance form essential for increase of clinical retention. However, these criteria required preparations to be more invasive, which violates not only the original intentions of the RBFPD, but may also have an adverse effect on retention due to loss of enamel, an important factor in bonding. PURPOSE. The object of this in vitro study was to compare the dislodgement resistance of the new types of RBFPDs, the conventional three-unit fixed partial denture, and conventional design of RBFPD (Maryland bridge). MATERIAL AND METHODS. Fifty resin mandibular left second premolars and second molars were prepared on dentiforms, according to the RBFPD design. After model fabrication (five group, n = 10), prostheses were fabricated and cemented with zinc phosphate cement. After cementation, the specimens were subjected to tensile loading at a cross head speed of 4 mm/min in a universal testing machine. The separation load was recorded and analyzed statistically using one-way analysis of variance followed by Duncan's multiple range test. RESULTS. Group V, the pin-retained RBFPDs, had the highest mean dislodgement resistance, whereas specimens of group II, the conventional RBFPDs, exhibited a significantly lower mean dislodgement resistance compared to the other 4 groups (P <.05). There were no significant differences between group I, III, and IV in terms of dislodgement resistance (P>.05). Group V had the highest mean MPa (N/$mm^2$) (P <.05). There was no significant difference between groups I, II, III and IV (P > .05). CONCLUSION. Within the limits of the design of this in vitro study, it was concluded that: 1. The modified RBFPDs which utilizes the original tooth undercuts and requires no tooth preparation, compared with the conventional design of RBFPDs, has significantly high dislodgement resistance (P < .05). 2. The modified RBFPDs which utilizes the original tooth undercuts and requires minimal tooth preparation, compared with the conventional FPDs, has significantly no difference in retention and dislodgement resistance)(P>.05). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P<.05).

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.63-67
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• 2009

STATEMENT OF PROBLEM. Use of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material. PURPOSE. This study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive. MATERIAL AND METHODS. Adhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material(Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level. RESULTS. The results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile bonding strength to Silfix-Imprint II at all drying periods. CONCLUSION. Significant increase in tensile bonding strength with Silfix-Aquasil and VPS Tray adhesive-Imprint II combination until 10 and 15 minutes respectively. Tray adhesive-impression material combination from the same company presented higher tensile bonding strength at all drying time intervals than when using tray adhesive-impression material of different manufactures.

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.107-112
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• 2009

STATEMENT OF PROBLEM. Macroscopic and especially microscopic properties of implant surfaces play a major role in the osseous healing of dental implants. Dental implants with modified surfaces have shown stronger osseointegration than implants which are only turned (machined). Advanced surface modification techniques such as anodic oxidation and Ca-P application have been developed to achieve faster and stronger bonding between the host bone and the implant. PURPOSE. The purpose of this study was to investigate the effect of surface treatment of titanium dental implant on implant stability after insertion using the rabbit tibia model. MATERIAL AND METHODS. Three test groups were prepared: sandblasted, large-grit and acid-etched (SLA) implants, anodic oxidized implants, and anodized implants with Ca-P immersion. The turned implants served as control. Twenty rabbits received 80 implants in the tibia. Resonance frequencies were measured at the time of implant insertion, 2 weeks and 4 weeks of healing. Removal torque values (RTV) were measured 2 and 4 weeks after insertion. RESULTS. The implant stability quotient (ISQ) values of implants for resonance frequency analysis (RFA) increased significantly (P <. 05) during 2 weeks of healing period although there were no significant differences among the test and control groups (P >. 05). The test and control implants also showed significantly higher ISQ values during 4 weeks of healing period (P < .05). No significant differences, however, were found among all the groups. All the groups showed no significant differences in ISQ values between 2 and 4 weeks after implant insertion (P >. 05). The SLA, anodized and Ca-P immersed implants showed higher RTVs at 2 and 4 weeks of healing than the machined one (P < .05). However, there was no significant difference among the experimental groups. CONCLUSION. The surface-modified implants appear to provide superior implant stability to the turned one. Under the limitation of this study, however, we suggest that neither anodic oxidation nor Ca-P immersion techniques have any advantage over the conventional SLA technique with respect to implant stability.

• The Journal of Advanced Prosthodontics
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• v.2 no.2
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• pp.33-38
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• 2010

PURPOSE. Marginal fit is a very important factor considering the restoration's long-term success. However, adding porcelain to copings can cause distortion and lead to an inadequate fit which exposes more luting material to the oral environment and causes secondary caries. The purpose of this study was to compare the marginal fit of 2 different all-ceramic crown systems before and after porcelain veneering. This study was also intended to verify the marginal fit of crowns originated from green machining of partially sintered blocks of zirconia (Lava CAD/CAM system) and that of crowns obtained through machining of fully sintered blocks of zirconia (Digident CAD/CAM system). MATERIALS AND METHODS. 20 crowns were made per each system and the marginal fit was evaluated through a light microscope with image processing (Accura 2000) at 50 points that were randomly selected. Each crown was measured twice: the first measurement was done after obtaining a 0.5 mm coping and the second measurement was done after porcelain veneering. The means and standard deviations were calculated and statistical inferences among the 2 groups were made using independent t-test and within the same group through paired t-test. RESULTS. The means and standard deviations of the marginal fit were $61.52{\pm}2.88{\mu}m$ for the Digident CAD/CAM zirconia ceramic crowns before porcelain veneering and $83.15{\pm}3.51{\mu}m$ after porcelain veneering. Lava CAD/CAM zirconia ceramic crowns showed means and standard deviations of $62.22{\pm}1.78{\mu}m$ before porcelain veneering and $82.03{\pm}1.85{\mu}m$ after porcelain veneering. Both groups showed significant differences when analyzing the marginal gaps before and after porcelain veneering within each group. However, no significant differences were found when comparing the marginal gaps of each group before porcelain veneering and after porcelain veneering as well. CONCLUSION. The 2 all-ceramic crown systems showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy.

• The Journal of Advanced Prosthodontics
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• v.12 no.2
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• pp.55-60
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• 2020

PURPOSE. The aim was to evaluate the effect of four acidic beverages on the roughness (Ra) and color change (ΔE_ab) of two brands of artificial teeth and a heat-polymerized acrylic resin (HPAR) for use in a prosthetic base. MATERIALS AND METHODS. All materials were divided into 5 groups, according to the used acidic beverage (artificial saliva - control, red wine, orange juice, coke-based, and lemon juice-based soft drink). The immersion process was divided into two stages: T1 - immersion in the acidic solutions for 10 minutes for 14 days; T2 - after T1, the samples were immersed in grape juice for 14 days. The Ra of the samples was evaluated in a rugosimeter and the ΔE_ab in a spectrophotometer, before and after the immersions. The analysis of variance of one (ΔE_ab) and two factors (Ra) and Tukey were performed (α=.05). RESULTS. There was a statistical difference for roughness after immersion (T1) for Trilux and Tritone teeth, regardless of the acid solution. For Trilux teeth, all acid solutions increased Ra (P<.05). For Tritone teeth, only the coke-based soft drink did not statistically change Ra. Grape juice (T2) altered Ra only of artificial teeth (P<.05). The color was changed for all materials, after T1 and T2. CONCLUSION. In general, the acidic solutions changed the Ra and ΔE_ab of HPAR and artificial teeth after T1. The grape juice altered the roughness only of the artificial teeth, promoting a clinically acceptable color change in the materials.

• The Journal of Advanced Prosthodontics
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• v.12 no.2
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• pp.100-106
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• 2020

PURPOSE. The purpose of this in vitro study was to evaluate the fitting accuracy of single crowns made from a novel presintered Co-Cr alloy prepared with a computer-aided design and computer-aided manufacturing (CAD/CAM) technique, as compared with crowns manufactured by other digital and the conventional casting technique. Additionally, the influence of oxide layer on the fitting accuracy of specimens was tested. MATERIALS AND METHODS. A total of 40 test specimens made from Co-Cr alloy were investigated according to the fitting accuracy using a replica technique. Four different methods processing different materials were used for the manufacture of the crown copings (milling of presintered (Ceramill Sintron-group_cer_sin) or rigid alloy (Tizian NEM-group_ti_nem), selective laser melting (Ceramill NPL-group_cer_npl), and casting (Girobond NB-group_gir_nb)). The specimens were adapted to a resin model and the outer surfaces were airborne-particle abraded with aluminum oxide. After the veneering process, the fitting accuracy (absolute marginal discrepancy and internal gap) was evaluated by the replica technique in 2 steps, before removing the oxide layer from the intaglio surface of the crowns, and after removing the layer with aluminum oxide airborne-particle abrasion. Statistical analysis was performed by multifactorial analysis of variance (ANOVA) (α=.05). RESULTS. Mean absolute marginal discrepancy ranged between 20 ㎛ (group_cer_npl for specimens of Ceramill NPL) and 43 ㎛ (group_cer_sin for crowns of Ceramill Sintron) with the oxide layer and between 19 ㎛ and 28 ㎛ without the oxide layer. The internal gap varied between 33 ㎛ (group_ti_nem for test samples of Tizian NEM) and 75 ㎛ (group_gir_nb for the base material Girobond NB) with the oxide layer and between 30 ㎛ and 76 ㎛ without the oxide layer. The absolute marginal discrepancy and the internal gap were significantly influenced by the fabrication method used (P<.05). CONCLUSION. Different manufacturing techniques had a significant influence on the fitting accuracy of single crowns made from Co-Cr alloys. However, all tested crowns showed a clinically acceptable absolute marginal discrepancy and internal gap with and without oxide layer and could be recommended under clinical considerations. Especially, the new system Ceramill Sintron showed acceptable values of fitting accuracy so it can be suggested in routine clinical work.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.122-130
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• 2006

Congenital Missing Teeth(hypodontia, oligodontia) is the developmental absence of one or more teeth. It has been reported as being the most common anomaly of dental development in human, relatively common in the permanent dentition. In a recent review, Vastardis has quoted incidence ranges of $1.6%{\sim}9.6%$ in the permanent dentition. Brook has quoted a prevalence of $3.5%{\sim}6.5%$ in most populations, with severe hypodontia, defined as the absence of six or more teeth, having a prevalence of $0.3{\sim}0.4%$. The most commonly affected teeth are third molars, followed by maxillary lateral incisor, and second premolars. The etiology is unknown, several hypotheses include trauma, nutritional deficiency, infection, metabolic abnormalities, systemic disease and genetic influence. The multiple congenital missing is commonly associated with specific syndrome or severe systemic abnormalities such as cleft lip & palate and Down's syndrome. These cases present that children have multiple congenital missing teeth in the permanent dentition, without any systemic disease. Management of this condition must be considered orthodontic and prosthodontic treatment comprehensively. In these cases, children were treated by space maintainer or orthodontic appliance and follow-up checked.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.366-376
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• 2013

The purpose of this study is to evaluate the marginal and internal fit of coping made by CAD/CAM using different scanning methods. Zirconia coping was made by each CAD/CAM system followed by intra-oral scanning, model optical scanning and model contact scanning. It was embedded into Epoxy Resin and was cut by buccal to lingual. AMD (Absolute marginal discrepancy), MG (Marginal gap), GA (Gap of axial), GL (Gap of line angle) and GO (Gap of occlusal) of each sample were measured. The result is as followed; 1. The mean value of AMD in Group 1, Group 2, Group 3 are $141.21{\pm}42.94{\mu}m$, $140.63{\pm}31.64{\mu}m$, $109.37{\pm}28.42{\mu}m$. The averages of MG in Group 1, Group 2, Group 3 are $82.52{\pm}43.99{\mu}m$, $90.28{\pm}27.93{\mu}m$, $66.55{\pm}28.77{\mu}m$. Statistically there is no difference in AMD and MG among the three Groups (Anova, P>0.05). 2. GA of Group 2 revealed statistically difference compared with Group 1 and Group 3 (Anova, P<0.05). 3. GL and GO of Group 1 showed statistically significant differences compared with Group 2 and Group 3 (Mann-whitney test (P<0.05). Zirconia copings made by 3 ways of scanning methods have no difference with conventional ceramics in AMD and MG which are known as the most important factors.

• The Journal of the Korean dental association
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• v.48 no.4
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• pp.280-287
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• 2010

Objective: In spite of increasing dental treatment for the disabled, there was a few collected data on dental treatment status and dentists' perception in Korea. The purpose of this' study is to research the current dental treatment status for the disabled in Korea and to suggest public health policies for the disabled. Material and methods: Total of 68 dentists who have treated the disabled regularly were asked to fill questionnaires regarding dental treatments for the disabled. Results: 1. It is necessary to set up public dental center for the disabled in rural area. 2. In case of dental treatments relating to cerebral palsy, ADHD, autism, the compensation for treatment time and extra investment is needed. 3. Only 39.7% of dentists charged treatment fees to the disabled as same as normal patients. Moreover 38.2% of dentists answered that they didn't charge treatment fees at all when their patient are disabled. 4.23.5% of dentists provided all of dental treatments including dental implant and orthodontic appliances in Korea. However, 54.3% of dentists reported the improvement of access to dental implant, orthodontic and esthetic treatment is needed. 5. It is imperative for the government to improve the support system for the disabled. Conclusions: Through this research only 26.5% of dentists answered that they had received the fund from the government and 11.1% of them were satisfied with the support for the disabled in Korea. This indicated the improvement of government financial support system for the disabled is needed.