• Restorative Dentistry and Endodontics
• /
• v.33 no.6
• /
• pp.570-579
• /
• 2008

The purpose of this study was to investigate the distribution of tensile stress of canal obturated maxillary second premolar with access cavity and notch-shaped class V cavity restored with composite resin using a 3D finite element analysis. The tested groups were classified as 8 situations by only access cavity or access cavity with notch-shaped class V cavity (S or N), loading condition (L1 or L2), and with or without glass ionomer cement base (R1 or R2). A static load of 500 N was applied at buccal and palatal cusps. Notch-shaped cavity and access cavity were filled microhybrid composite resin (Z100) with or without GIC base (Fuji II LC). The tensile stresses presented in the buccal cervical area, palatal cervical area and occlusal surface were analyzed using ANSYS. Tensile stress distributions were similar regardless of base. When the load was applied on the buccal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth with class Ⅴ cavity were slightly higher than that of the tooth without class V cavity. When the load was applied the palatal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth without class V cavity were slightly higher than that of the tooth with class V cavity.

• The Journal of the Korean dental association
• /
• v.26 no.8 s.231
• /
• pp.693-699
• /
• 1988

Composite Resin(콤포짓트 레진) 수복은 3급,4급(견치의 원심면 제외) 및 5등급 전치부와동에 주로 사용되었으나 재료의 개선으로 인해 1급,2급 및 견치 3급와동의 원심면에도 제한적으로 사용이 가능하게 되었다. 물론 실제적인 와동의 설계는 수복요건에 따라 다양한 형태변화를 부여할 수도 있다.

• Restorative Dentistry and Endodontics
• /
• v.29 no.1
• /
• pp.1-12
• /
• 2004

이 연구는 발거 소구치에서 5급 와동을 형성하여 접착 시스템 및 와동 위치에 따른 상아질에 대한 접착시스템의 미세 인장결합강도의 차이를 비교, 연구하였다. 접착방법은 resin-modified glass ionomer(Gl), compomer(부식여부에 따라 DE 및 DN군으로 분류), 그리고 상아질 접착제인 Single Bond(SB) 및 Cleayfil SE Bond(SE)와 복합레진(Clearfil AP-X)을 사용한 5개의 실험군으로 분류하였다. 소구치 협측 치경부에 wedge형태의 와동을 형성하고 5종의 접착 시스템을 제조자의 지시에 따라 적용, 충전하여 시편을 제작하여 미세인장결합강도를 측정하고, One-way ANOVA / Duncan's test로 통계분석하였다. SEM 검사는 미세인장결합강도의 시편제작과 동일한 방법으로 시편을 제작한 후 관찰하였다. 실험 결과, 상아질 접착제 및 복합레진(SB, SE)의 미세인장결합강도가 GI보다 높게 나타났고(p<0.05), 치은측이 교합측보다 더 낮게 나타났으며, CI, DE, SE에서 유의성 있게 낮게 나타났다(p<0.05). Compomer에서 conditioning 여부(DN, DE)에 따른 변화는 치은측에서만 유의차 있는 것으로 나타났다. SEM 관찰에서, 교합측의 상아세관은 결합 계면과 평행하게 주행하였고, 치은측에서는 결합계면에 수직으로 주행하는 것으로 관찰되었다.

• Restorative Dentistry and Endodontics
• /
• v.34 no.6
• /
• pp.477-483
• /
• 2009

The purpose of this study was to compare the microleakage of low and high viscosity flowable resins in class V cavities applied with 1-step adhesives. Forty Class V cavities were prepared on the cervices of buccal and lingual surfaces of extracted molar teeth and divided into four groups (n=8). Cavities were restored with AQ Bond Plus /Metafil Flo $\alpha$, G-Bond/ UniFil LoFlo Plus (Low flow groups), AQ Bond Plus/Metafil Flo and G-Bond/UniFil Flow (High flow group), respectively. Specimens were immersed in a 2% methylene blue solution for 24 hours, and bisected longitudinally. They were observed microleakages at the enamel and dentinal margins. In conclusion, the low viscosity flowable resins showed lower marginal microleakage than do the high vis cosity flowable resins in class V cavities.

• Restorative Dentistry and Endodontics
• /
• v.32 no.5
• /
• pp.437-444
• /
• 2007

The purpose of this study was to compare the marginal microleakage of different 2-step adhesive systems in Class V cavities prepared with different diamond points. Forty Class V cavities were prepared with two different (coarse or fine) diamond points on cervical third of extracted molars. The occlusal and gingival margin of cavities was located in enamel and dentin, respectively. They were divided into one of four equal groups (n = 10) and ; Group 1-prepared with coarse diamond point (EX-41), restored with Single Bond and Z 250, Group 2-prepared with fine diamond piont (TF-21F), restored with Sing)e Bond and Z 250, Group 3-prepared with coarse diamond point (EX-41), restored with Clearfil SE Bond and Clearfil AP-X, Group 4-prepared with fine diamond point (TF-21F), restored with Clearfil SE Bond and Clearfil AP-X. Specimens were thermocycled, immersed in a 2% methylene blue solution for 24 hours, and bisected longitudinally. They were observed leakages at enamel and dentinal margins. Data were analyzed using Mann-Whitney and Wilcoxon signed ranked test. In this study, marginal microleakage or Single Bond was not affected by type of diamond points. But Clearfil SE Bond showed higher marginal microleakage at both enamel and dentinal margin when Class V cavity was prepared with coarse diamond point.

• Restorative Dentistry and Endodontics
• /
• v.31 no.1
• /
• pp.20-29
• /
• 2006

The purpose of this study was to analyze the stress distribution aspect of unrestored and restored combined shape (wedge shape occulusally and saucer shape gingivally) class V cavity, which found frequently in clinical cases. A maxillary second permolar restored with a combined shape class V composite restorations were modeled using the three dimensional finite element method. Static occlusal load of 170 N was applied on lingual incline of buccal cusp at the angle of $45^{\circ}$ with the longitudinal axis of the tooth. And three dimensional finite element analysis was taken by ANSYS (Version 6.0, Swanson Analysis System Co., Houston, U.S.A) program which represent the stress distribution on unrestored and restored cavity wall and margin. The conclusions were as follows. 1. Compared to the unrestored cavity, Von Mises stress at the cementoenamel junction and line angle of the cavity base were reduced and in restored cavity. 2. Von Mises stress at the occlusal and cervical cavity margin and wall were increased in restored cavity in comparison with the unrestored cavity. 3. In the hybrid and hybrid/flowable composite resin restoration, Von Mises stress at the cementoenamel junction and line angle of the cavity base were reduced more than in the flowable restoration. 4. In the hybrid and hybrid/flowable composite resin restoration, Von Mises stress at the occlusal and cervical cavity margin and wall were increased more than in the flowable restoration.

• Restorative Dentistry and Endodontics
• /
• v.35 no.2
• /
• pp.116-124
• /
• 2010

This study aimed to assess whether the gender of the dental practitioner affects operative techniques in class 2 and class 5 resin composite restorations. In 2008, a nationwide survey was given to Korean dentists. Total 12,193 e-mails were distributed, 2,632 were opened by recipients, and 840 responses were collected. Of the respondents, 78.9% were male and 21.1% were female. The gender distribution in the age groups between respondents and the total population did not differ (p > 0.05). A chi-square test was used to compare technical differences between female and male dentists. A multiple logistic regression analysis was performed to assess the association between gender and operative techniques in resin composite restoration. For class 2 resin composite restoration, female dentists were 1.87 times more likely than male dentists to do multiple incremental fillings (four layers or more) and 2.72 times more likely than males to spend 30 minutes or more for the treatment (p < 0.05). For class 5 resin composite restoration, female dentists were 2.69 times more likely than their male counterparts to use a cavity base or liner, 1.83 times more likely to do multiple incremental fillings (four layers or more) and 1.63 times more likely to spend 20 minutes or more for the procedure (p < 0.05). The gender factor was influential to individual operative techniques in restorative treatment.

• Restorative Dentistry and Endodontics
• /
• v.34 no.2
• /
• pp.87-94
• /
• 2009

The purpose of this study was to assess the current materials, methods and difficulties according to the year of licence and educational background of Korean dentists in Class II direct composite resin restorations. Total 17 questions were included in the questionnaire. Questions were broadly divided into two parts: first. operator's information. and second. the materials and methods used in Class II posterior composite restoration. The questionnaire was sent to dentists enrolled in Korean Dental Association via e-mail. Total 12,193 e-mails were distributed to dentists. 2,612 e-mails were opened, and 840 mails (32.2%) were received from respondents. The data was statically analyzed by chi-square test using SPSS(v. 12.0.1, SPSS Inc. Chicago, IL, USA). Male dentists among respondents was 79%. 60.3% of the respondents acquired their licences recently (1998-2007), and 77% practiced in private offices. 83.4% have acquired their knowledge through school lectures, conferences and seminars. For the Class II restorations, gold inlays were preferred by 65.7% of respondents, while direct composite resin restorations were used by 12.1 % amalgam users were only 4.4% of respondents. For the restorative technique, 74.4% of respondents didn't use rubber dam as needed. For the matrix. mylar strip (53.4%), metal matrix (33.8%) and Palodent system (6.5%) were used. 99.6% of respondents restored the Class II cavity by incremental layering. Obtaining of the tight interproximal contact was considered as the most difficult procedure (57.2%) followed by field isolation (21 %). Among various bonding systems, 22.6% of respondents preferred SE Bond and 20.2% used Single Bond. Z-250 was used most frequently among a variety of composite resins.

• Restorative Dentistry and Endodontics
• /
• v.33 no.5
• /
• pp.428-434
• /
• 2008

The purpose of this study was to compare the microtensile bond strength in Class I cavities associated with different light curing modes of same light energy density. Occlusal enamel was removed to expose a flat dentin surface and twenty box-shaped Class I cavities were prepared in dentin. Single Bond (3M Dental product) was applied and Z 250 was inserted using bulk technique. The composite was light-cured using one of four techniques, pulse delay (PD group), soft-start (SS group), pulse cure (PC group) and standard continuous cure (CC group). The light-curing unit capable of adjusting time and intensity (VIP, Bisco Dental product) was selected and the light energy density for all curing modes was fixed at $16J/cm^2$. After storage for 24 hours, specimens were sectioned into beams with a rectangular cross-sectional area of approximately $1mm^2$ Microtensile bond strength $({\mu}TBS)$ test was per- formed using a univel·sal testing machine (EZ Test, Shimadzu Co.). The results were analyzed using oneway ANOVA and Tukey's test at significance level 0.05. The ${\mu}TBS$ of PD group and SS group was higher than that of PC group and CC group. Within the limitations of this in vitro study, modification of curing modes such as pulse delay and soft start polymerization can improve resin/dentin bond strength in Class I cavities by controlling polymerization velocity of composite resin.

• Restorative Dentistry and Endodontics
• /
• v.27 no.4
• /
• pp.394-402
• /
• 2002

2급 복합레진 수복 와동의 치은 변연이 상아질 상에 있을 때 유동성 레진 이장의 유무와 두께가 미세누출에 미치는 영향을 알아보기 위해 본 실험을 시행하였다. 60개의 발거된 대구치의 근, 원심면에 각각 협설측 3mm, 치은벽 깊이 1mm의 2급 와동을 형성하고 치은 변연은 법랑-백아 경계에서 약 1mm 하방에 위치 시켰다. 모든 와동을 32% 인산으로 15초 처리 및 30초 수세 후 Prime & Bond$^{\circledR}$ NT 상아질 접착제를 적용하였고, Tetric Ceram(TC), Tetric Flow(TF)를 이용하여 다음의 6가지 군으로 나누어 수복하였다. (1) TC로 수평 적층 충전, (2) TC로 수직 적층 충전, (3) 0.5-1mm두께로 TF 이장 후 TC로 수평적층 충전, (4) 0.5-1mm 두께로 TF 이장 후 TC로 수직 적층 충전, (5) 2-3mm 두께로 TF 이장 후 TC로 수평적층 충전, (6) 2-3mm두께로 TF이장 후 TC로 수직 적층 충전. 충전된 시편을 37$^{\circ}C$ 100% humidity에서 24시간 보관하고 5$^{\circ}C$와 55$^{\circ}C$에서 500회의 열순환을 실시하여 치은 변연의 0.5mm 외부에 nail varnish를 도포 하여 2% methylene blue 용액에 12시간 침잠시켰다. 시편을 아크릴릭 레진에 매몰하여 수복물의 중앙에서 종절단 한 후 입체현미경하에서 색소의 침투도를 관찰하여 다음과 같은 결과를 얻었다. 유동성 레진의 이장을 시행한 군과 하지 않은 군간에 미세누출은 유의차를 보이지 않았다(p>0.05) 유동성 레진의 두께에 따른 미세누출의 차이는 나타나지 않았다(p>0.05) 경사면 충전법을 시행한 군에서는 유동성 레진을 이장한 군들이 이장하지 않은 군보다 유의하게 많은 누출을 보였다(p<0.05). 수평적층 충전법을 시행한 군에서는 유동성 레진 이장이 미세누출에 유의한 차이를 보이지 않았다(p>0.05).