• Restorative Dentistry and Endodontics
• /
• 제28권4호
• /
• pp.341-347
• /
• 2003

This study was conducted to evaluate the temperature rise on the root surface while the root canal is being obturated using continuous wave of condensation technique. Maxillary central incisor was prepared for repeated canal obturation. Ten thermocouples (Omega Engineering Inc., Stanford, USA) were placed at 1 mm increment from the anatomical root apex. The real temperature of Buchanan plugger was recorded before insertion into the root canal. The root canal was obturated with continuous wave of condensation technique as described by Buchanan and the root surface temperature was recorded during obturation at $150^{\circ}C,{\;}200^{\circ}C,{\;}250^{\circ}C{\;}and{\;}300^{\circ}C$ temperature settings of System B HeatSource (Model 1005, Analytic technologies, Redmond, WA, USA). After completion of the temperature recording, the dentinal-cementum thickness at each sites was measured. The data were analyzed using one-way ANOVA followed by Scheffe's test and linear regression test. The results were as follows. 1. When the temperature was set at $150^{\circ}C,{\;}200^{\circ}C,{\;}250^{\circ}C{\;}and{\;}300^{\circ}C$ on the digital display of System B HeatSource, the real temperature of the plugger at the 1mm point from the tip revealed $130.82{\pm}2.96^{\circ}C,{\;}158.00{\pm}5.26^{\circ}C,{\;}215.92{\pm}6.91^{\circ}C{\;}and{\;}249.88{\pm}3.65^{\circ}C$ respectively. 2. The position of 8 mm from the anatomical apex showed the highest temperature increase at each temperature settings and it was significantly higher than those of other positions (p<0.0l). The temperature rise was constantly increased toward coronal portion from apex of the root. 3. The maximum temperature increase on the root surface was $2.37{\pm}0.09^{\circ}C{\;}at{\;}150^{\circ}C{\;}setting,{\;}3.11{\pm}0.12^{\circ}C{\;}at{\;}200^{\circ}{\;}setting,{\;}3.93{\pm}0.09^{\circ}C{\;}at{\;}250^{\circ}C{\;}setting{\;}and{\;}5.69{\pm}0.15^{\circ}C{\;}at{\;}300^{\circ}C$ setting respectively. These results suggest that it be relatively kind to the supporting tissues of the root that the root canal is obturated using continuous wave of condensation technique at $150^{\circ}C,{\;}200^{\circ}C,{\;}250^{\circ}C{\;}and{\;}300^{\circ}C$ temperature settings on digital temperature display of System B HeatSource.

• Restorative Dentistry and Endodontics
• /
• 제35권2호
• /
• pp.134-142
• /
• 2010

이 연구의 목적은 상아질 지각과민증 모드의 Er,Cr:YSGG 조사가 복합레진 수복물의 미세인장 결합강도에 미치는 영향을 평가하는 것이다. 20개의 발거된 대구치를 사용하여 Er,Cr:YSGG 레이저 적용 유무와 사용된 접착제 시스템(Optibond FL과 Clearfil SE bond), 산의 적용 시간(15초와 20초)에 따라 여섯 그룹으로 나누었다. 노출된 교합면 상아질에 레이저 조사 후 접착제를 도포하고 복합레진으로 수복하였다. 24시간 동안 실온의 증류수에 보관 후 각 그룹 당 12개의 시편을 준비하였다. 모든 시편의 미세인장 결합강도를 측정하고 파절 양상을 관찰하였다. 더불어 레이저를 조사한 시편과 조사하지 않은 시편을 주사현미경을 이용하여 관찰하여 다음과 같은 결과를 얻었다. 1. 레이저를 조사한 그룹은 레이저를 조사하지 않은 그룹보다 낮은 미세인장 결합강도를 나타내었다. 2. 레이저 조사 유무와 관계없이, Optibond FL이 Clearfil SE bond보다 높은 미세인장 결합강도를 나타냈으며, Optibond FL을 사용했을 때 산부식 시간이 20초인 경우가 15초인 경우보다 더 높은 값을 나타내었다. 3. 레이저를 조사한 상아질의 SEM 사진은 관간상아질보다 관주상아질이 더 두드러져 보이며, 상아세관이 열려있으며 도말층은 관찰되지 않았다.

• Restorative Dentistry and Endodontics
• /
• 제29권5호
• /
• pp.430-438
• /
• 2004

This study evaluated the influence of application time of self-etching primers on microtensile bond strength (${\mu}$TBS) to dentin using three self-etching primer adhesive systems. Dentin surfaces were exposed from forty-eight human molars. They were conditioned with three self-etching primers (Clearfil SE Bond [SE], Unifil Bond [UF], Tyrian SPE + One Step Plus [TY]) and different primining times (10s, 20s, 30s and 40s). Composite resins were bonded to dentin surfaces and specimens were made. ${\mu}TBS$ was tested and statistically compared using by one-way ANOVA and Tukey's Test. The results of this study presented that priming time for 10s in SE and UF groups and for 30s and 40s in TY group was highly decreased ${\mu}TBS$ to dentin.

• Restorative Dentistry and Endodontics
• /
• 제20권2호
• /
• pp.832-838
• /
• 1995

The purpose of this study was to evaluate the amount of marginal microleakage of 2 light curable GI cements(Fuji II LC & VariGlass), which contain some resin components. 4 volunteers kept on acrylic resin plates, which contained dentin disks with cavities filled with test materials for 2 weeks. The time when polishing was done(5 minutes and 24 hours after filling) and the use of protective agents were varied, so 8 groups with each 6 specimens were tested. After having specimens(disks with cavities filled with materials) penetrated with 1% Methylene Blue solution, specimens were stored in 40% nitric acid solution for 4 days to extract adsorbed dye material. Supernatants of centrifuged samples were diluted 5 times and Spectrophotometer was used to determine the degree of absorption. Dye concentration was calculated through the pre-obtained Linear Regression Curve. The results were as follows. 1. The best result was seen in groups (PF24, PV24) which were protected and polished 24 hours later and the opposite phenomenon was seen in groups(NF24, NV24) which were held without protection and polished 24 hours later. Groups polished S minutes later showed moderate leakage pattern. 2. Groups polished 5 minutes later showed similar leakage amount irrespective of using of protective agent. But statistically insignificant lower values were seen in VariGlass than in Fuji II LC groups, So It was considered that VariGlass may be more resistant to early moisture attack than Fuji II LC. 3. In groups polished 24 hours later, there was no significant difference between materials but was definitely significant difference according to the use of protective agent. If the cement in which polishing will be done 24 hours later, Protective agent should be used to cover the surface.

• Restorative Dentistry and Endodontics
• /
• 제29권3호
• /
• pp.233-238
• /
• 2004

The purpose of this study was to evaluate the effect of immediate or delayed composite resin filling on dentinal microtensile bond strength (${\mu}TBS$) after applied the adhesive. The coronal dentin of human third molars was exposed. Single-Bond or One-Step was applied on the dentin surfaces. and composite resin were constructed immediately (group 1) or 5min., 10min., 15min., 20min. and 30min. (groups 2-6) after an adhesive was applied. The specimens were sectioned and made bar-shaped. Each surface area of them was about $1\textrm{mm}^2$. The ${\mu}TBS$ test was performed by EZ test. The results were analysed by One-way ANOVA and Tukey's test at 95% significance level. The results suggested that the ${\mu}TBS$ of Single-Bond to dentin was decreased when the composite resin was constructed 20min. and 30min. after Single-Bond was applied. But the ${\mu}TBS$ of One-Step was not affected by delayed composite resin filling.

• Restorative Dentistry and Endodontics
• /
• 제25권1호
• /
• pp.116-122
• /
• 2000

On the instrumented root canal wall, amorphous, irregular smear layer can be observed with Scanning Electron Microscope(SEM). The purpose of this study was to evaluate the effect of the presence or absence of smear layer on the adhesion of Staphylococcus aureus to the dentin of the root canal. Human incisors, extracted within 7 days, with no caries, no fracture, no calcification of canal, were selected. After cutting crown portion at cemento-enamel junction, root canal preparation was done by modified crown-down technique using Profile and Gates - Glidden Drill. During canal preparation, 10ml physiologic saline solution(group1&3) or 10ml 3.5% NaOCl(group2&4) was used as irrigation solution. And 10ml physiologic saline solution(group1&3) or 10ml 0.5M EDTA(group2&4) was applicated for final flush. After vertical sectioning and ethylene oxide gas sterilization, samples(group1&2) were immersed into BHIYHM broth inoculated with Staphylococcus aureus (ATCC 31153) and incubated for 3hrs at $37^{\circ}C$. All samples were prepared for and observed with SEM(JEOL JSM840S). The data were analyzed by Mann-Whitney rank sum test. The conclusions are as follows ; 1. Smear layer covers entire root canal surface after root canal preparation. 2. Smear layer has been removed away and the entrances of dentinal tubules have opened widely, when applying 0.5M EDTA and 3.5% NaOCl. 3. A significantly higher number of bacteria were adhered to the root canal dentin without smear layer(p<0.0001). 4. Smear layer produced during root canal preparation impedes bacterial adhesion and colonization to dentin matrix, therefore inhibits canal reinfection.

• Restorative Dentistry and Endodontics
• /
• 제17권1호
• /
• pp.36-54
• /
• 1992

The purpose of this study was to compare the shear bond strengths to ground dentin surfaces of four dentinal bonding agents in 193 teeth. Various dentin surfaces treated with four dentin bonding agents were attached with two restorative composite resins. The effectiveness of the bonding were tested by the monitoring the shear bond strength. The shear bond strengths were measured after 2 hours and 24 hours after surface conditioning with four dentin bonding agents. Effects of EDTA, the additive illumination, and sealer treatments without primer on bond strength to dentin surfaces were assessed. In addition the effects of the thickness of specimens ranging from 0.65 mm to 1.95 mm and the ratio of catalyst and base paste on the bond strength of chemical cure composite resin were estimated. The shear bond strength was determined by testing specimens in the Instron universal testing machine (Model No. 1122) at a crosshead speed of 1.0 mm/min. Following condusions were drawn: 1. The highest mean shear bond strengths of chemical cure composite resin to dentin conditioning with dentin bonding agents aged 2 hours were obtained, and then that was decreased with time followed by EDTA treatment. 2. In light cure composite resin, the shear bond strength was increased following dentin conditioning with bonding agents with time, irradiation time and EDTA treatment except in SB group. 3. The thicker the composite resin specimen was, the less the shear bond strength in chemical cure composite resin was. 4. In light cure composite resin, there was a little change in shear bond strength following dentin conditioning with bonding agents. 5. In chemical cure composite resin, the shear bond strength was the highest in the ratio of 1/1 of catalyst and base part. 6. Without a dentin primer, shear bond strength to dentin conditioned only with UB sealer was the highest among four sealers in light cure composite resin.

• 대한치과보존학회:학술대회논문집
• /
• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
• /
• pp.608-608
• /
• 2003

The main objectives of root canal therapy are cleaning and shaping and then obturating the root canal system in 3 dimensions to prevent reinfection. Many instrumentation techniques and devices, supported by an irrigation system capable of removing pulp tissue remnants and dentin debris, have been proposed to shape root canals. But current regimens in chemomechanical debridement using instrumentation and irrigation with NaOCl are not predictably effective in root canal disinfection. These findings are not surprising because the root canal system is complex and contains numerous ramifications and anatomical irregularities. The microorganisms in root canals not only invade the anatomic irregularities of the root canal system but also are present in the dentinal tubules. Therefore further disinfection with an effective antimicrobial agent may be necessary and it well1mown that use of intracanal medication will lower bacterial count in infected root canals. Calcium hydroxide has a long history of use in endodontics, and more attention has been given to the use of calcium hydroxide as intracanal dressing for the treatment of infected pulp. However, when treatment is completed in one visit, no intracanal medications other than intracanal irrigants are used. Recently, a mixture of a tetracycline isomer, an acid, and a detergent(MTAD), has been introduced as a final rinse for disinfuction of the root canal system. It has been shown that MTAD is able to remove the smear layer with minimal erosive changes on the surface of dentin, and is effective against Enterococcus faecalis, a microorganism resistant to the action of other antimicrobial medications. In another study, the ability of MTAD was investigated to disinfect contaminated root canals with whole saliva and compared its efficacy to that of NaOCl Based on the results, it seems that MTAD is significantly more effective than 5.25% NaOCl in eradicating bacteria from infected root canals. In the cytotoxicity evaluation, MTAD is less cytotoxic than engenol, 3% $H20_2,\;Ca(OH)_2$ paste, 5.25% NaGCl, Peridex, and EDTA and more cytotoxic than 2.63%,1.31% and 0.66% NaOCl. Is it promising or transient?

• 대한치과보철학회지
• /
• 제31권1호
• /
• pp.1-10
• /
• 1993

The purpose of this study was to evlauate the microleakage of 3 dentin bonding agents using different dentin pretreatment method under simulated physilogic pressure in cementing the porcelain laminate veneer. Noncarious 60 human maxillary molars were selected and randomly assigned to 4 groups of 15 each. The group with the margin placed on the enamel was classified as the control and the groups with the margin placed on root surface were subdivided into 3 groups according to the dentin bonding agents used. The group using All Bond 2 was classified as experimental group 1, the group using Scotchbond MP was classified as experimental group 2, and the group using Gluma was classified as experimental group 3. Roots were removed at 3mm below the cementoenamel junction, and reductions of the teeth for the porcelain laminate veneer were done on the mesial 1/2 of the buccal surface of each teeth. The pulp was extirpated and the pulp chamber was cleaned with 37% phosphoric acid for the patency of dentinal tubule. Under simulated physiologic pressure, porcelain laminate veneers were cemented to the teeth using each dentin bonding agent and luting cement. After cementation, all samples were stored at 36t in water for 24 hours and thermocycled for 1500 cycles, then immersed in 0.5% basic fuchsin solution and the teeth were sectioned longitudinally by using diamond saw and the extent of microleakage was measured. The following results were obtained, 1. Microleakage was observed in a few samples of control group but all the samples of experimental groups. 2. The control group showed the less extent of microleakage than the experimental groups. In experimental groups the experimental group 1 & the experimental group 2 showed similiar extent of microleakage and the experimental group 3 showed the greater extent of microleakage than other groups. Conclusively, practicing the porcelain laminate veneers in the clinic, although the margin of the porcelain laminate veneer should be placed on enamel, in the case that it is inevitable to place the margin of the porcelain laminate veneer on the root surface, it is recommened to use dentin bonding agents which use no dentin pretreatment or a dentin pretreatment which can leave the smear plugs.

• 대한소아치과학회지
• /
• 제27권4호
• /
• pp.524-534
• /
• 2000

유치 치근 흡수가 일어나는 경우는 임상에서 많이 접할 수 있다. 유치 치근 흡수는 나이에 따른 생리적 흡수와 치아우식증 및 외상 등으로 비정상적으로 흡수되는 염증성 흡수로 나눌 수 있다. 염증성 흡수는 그 시기와 양상이 생리적인 치근 흡수와는 다르며, 흡수기전이나 흡수면의 미세구조에 있어서도 많은 차이가 있을 것으로 사료된다. 유치 치근 흡수면의 미세구조에 대한 연구는 많이 있었으나, 생리적 흡수면과 염증성 흡수면의 미세구조를 비교한 연구는 드물다. 본 연구는 생리적 흡수면과 염증성 흡수면의 형태 및 인접한 세포를 연구하기 위하여 생리적 및 염증성 흡수로 인해 발거된 유치 치근의 흡수 표면을 주사전자현미경상으로, 조직학적 형태를 광학현미경상으로 관찰하여 다음과 같은 차이점을 알 수 있었다. 1. 주사전자현미경상에서 생리적 유치 치근 흡수 표면은 타원형, 원형 및 다각형 모양의 흡수소와가 관찰되었고, 염증성 흡수 표면은 크기가 작으며 형태가 다양하고 매우 불규칙한 무정형 형태의 흡수소와가 관찰되었다. 2. 광학현미경상에서 생리적 유치 치근 흡수면은 흡수소와로 구성된 규칙적인 큰 흡수와가 관찰되었고, 염증성 흡수면은 불규칙한 흡수소와가 관찰되었다. 3. 광학현미경상에서 생리적 유치 치근 흡수면에는 다핵거대세포가 흡수소와에 직접 접하고 있었으며, 염증성 흡수면은 간엽세포 및 염증세포가 많이 관찰되었다. 4. 광학현미경상에서 염증성 치근 흡수면에서는 상아질 흡수를 보상하는 부분적인 백악질 형성이 관찰되었다.