A comparison of microtensile bond strengths of several dentin bonding systems to primary and permanent dentin.

OBJECTIVES: Limited information exists with regard to the adhesive ability of glass ionomer cements (GIC) and recently developed resin-based dentin bond systems to primary dentin. The aim of this study was to compare the microtensile bond strength of a conventional GIC (Fuji IX), a resin-modified GIC (Fuji II LC), and two resin-based dentin adhesives (Prime and Bond NT with NRC and Single Bond). The bonded interfaces were also observed using field emission electron microscopy(FE-SEM). METHODS: Microtensile bond test specimens were prepared on superficial dentin of primary and permanent molars. The specimens were bonded according to each manufacturer's instructions except for Prime and Bond NT/NRC which used Silux Plus resin composite instead of Dyract. Hour-glass shaped specimens were created (diameter of 1.2+/-0.02 mm) and stressed in tension at a crosshead speed of 1mm/min. Results were analyzed using two-way ANOVA and LSD test, fracture modes were analyzed using the Mann-Whitney U-test and Kruskall-Wallis test. Twelve specimens were prepared for each material on primary and permanent dentin. Samples were prepared in the same manner, then critical point dried, fractured and sputter-coated for the FE-SEM observations. RESULTS: Two-way ANOVA showed the overall bond strengths were greater for the permanent dentin compared with primary dentin. However, for individual material comparisons no differences among the bond strengths to primary and permanent dentin for Fuji IX (9.7, 12.2 MPa), Fuji II LC (16, 20.1 MPa), Prime & Bond NT/NRC (18.1, 21.6 MPa) and Single Bond (18.2, 21.6 MPa), were detected. However, Fuji IX bond strengths were significantly lower than the other systems tested when bonded to either primary or permanent dentin (p<0.05). Failure mode showed cohesive failure of GIC and mostly adhesive failure for the resin-based adhesives. The FE-SEM observations showed hybrid-like layer formation for the GIC materials and hybrid layer formation for the resin-based adhesives. SIGNIFICANCE: The materials tested would be suitable for bonding to either primary or permanent dentin, but the resin-modified GIC or resin-based systems are likely to provide a stronger bond than the conventional GIC, Fuji IX.     

Effect of bur type on microtensile bond strengths of self-etching systems to human dentin

PURPOSE: To compare the microtensile bond strength (microTBS) of five adhesives to human dentin prepared with 600-grit SiC abrasive paper (SiC), a diamond rotary instrument, or a carbide bur. The null hypothesis was that different cavity preparation instruments do not affect adhesion of resin adhesives. MATERIALS AND METHODS: Human molars (n = 45) were randomly divided into three groups according to surface treatment. Each group was bonded using a total-etch adhesive (Single Bond, 3M ESPE), one of three self-etching primer systems (Clearfil SE Bond or ABF, Kuraray; Imperva Fluorobond, Shofu), or a self-etching adhesive (One-Up Bond F, Tokuyama). A 4-mm composite crown was built over the bonded surface. Specimens were stored in water for 24 h at 37 degrees C. They were sectioned into 0.7-mm-thick slabs, trimmed to a cross-sectional area of 1 mm2, and loaded to failure at a crosshead speed of 1 mm/min using a tabletop tester (EZ-Test, Shimadzu). Microtensile bond strength data were analyzed using analysis of variance and Fisher's PLSD test. RESULTS: Surface preparation using a carbide bur generally yielded higher bond strengths than preparation using either a diamond rotary instrument or SiC abrasive paper. SE Bond had the highest mean microTBS of the five adhesives tested. CONCLUSION: Resin-dentin bond strengths can be affected by the type of instrument used to prepare the tooth. Specifically, higher bond strengths might be achieved by using carbide burs rather than diamond cutting instruments.     

Comparison between regional micropush-out and microtensile bond strength of resin composite to dentin

The present study analyzed the prevalence of dental caries as well as associations of dental health and family competence among 7-year-old children and their families. Dental caries status was the outcome variable of the 7-year prospective follow-up study. Pre-tested questionnaires were used to gather data individually from the parents at six points in time (at the public maternity health-care clinic during the mother's pregnancy and at childbirth, at the well-baby clinic at 18 months, and at ages 3, 5, and 7 years). Clinical examinations at dental health-care clinics were used to record dental status indicators of the child at ages 3, 5, and 7 years. A child had caries more often when the mother did not regard it as important to teach a healthy lifestyle right from birth; when the mother undervalued consistent action in child-rearing; when the father preferred merely to explain the causes and consequences during child-rearing (giving no examples); when the father had several new carious teeth per year; when the child consumed sweets several times a week; or when the child's toothbrushing was infrequent. The child's daily dental health behaviors and a strong influence of family competence emerged in the final logistic regression analysis. Dental and well-baby clinic staff members need to discuss consistency in child-rearing with the parents and there is a need for modeling adult dental health behaviors at the time of the mother's pregnancy if the child's future preventive dental health is to function properly.     

Microtensile bond strengths of composite to dentin treated with desensitizer products

PURPOSE: This study was designed to analyze the influence of desensitizing procedures on dentin bond strength. MATERIALS AND METHODS: Forty bovine incisors were used, divided into four groups (n = 10): G1: control; G2: Gluma Desensitizer (Heraeus Kulzer); G3: Oxa-Gel (Art-Dent); G4: low-intensity laser (MMOptics). The buccal surface was wet ground flat with 180-, 400- and 600-grit silicon carbide abrasive paper to expose midcoronal dentin and create a uniform surface. After the application of the desensitizing agents to the exposed dentin, the specimens were etched with 35% phosphoric acid for 30 s, and an adhesive (Single Bond) was applied and light cured. A 4-mm high crown of composite resin (Filtek Z250) was then built up. Specimens were trimmed to an hourglass shape with cross sections of 1 mm2. Each specimen was individually fractured by a microtensile testing machine at a crosshead speed of 0.5 mm/min. The data, recorded in MPa, were analyzed with one-way ANOVA and the Duncan test (p = 0.05). RESULTS: Specimens treated with dentin desensitizers (except Gluma) yielded significantly lower mean bond strengths than nontreated control specimens. The mean values in MPa (+/- SD) were: G1: 13.4 (6.2); G2: 13.2 (4.8); G3: 7.15 (4.3); G4: 7.21 (4.6). CONCLUSIONS: Among the desensitizing agents studied, only Gluma Desensitizer did not detrimentally influence the bond strength values. It is a useful material for dentin desensitization.     

循环加载对氟斑牙牙本质粘接性能的影响

目的：评价循环加载对正常牙及不同程度氟斑牙牙本质微拉伸粘结强度的影响。方法：24个新鲜拔除的无龋第三磨牙和氟斑磨牙根据Dean氏指标分为正常、轻度、中度、重度4组。垂直牙体长轴除去冠部釉质,在面制备盒形洞,用Prime＆BondNT粘结,复合树脂充填。每组再随机分成实验组和对照组,实验组以50N大小的力进行循环加载,加载10000次。制备测试微拉伸粘结强度的条状试件,在拉力试验机上测定粘结强度。结果：对照组中正常组、轻度组、中度组、重度组的微拉伸粘结强度分别为：（43.98±6.28）MPa、（39.83±8.70）MPa、（29.41±5.76）MPa、（19.61±4.15）MPa;加载组中正常组、轻度组、中度组、重度组的微拉伸粘结强度分别为：（35.13±7.81）MPa、（30.53±8.47）MPa、（21.66±6.51）MPa、（13.93±4.90）MPa。结论：循环加载10000次使所有粘接试件的微拉伸粘结强度下降;无论加载与否,粘接强度都随着牙齿氟化程度增加而降低,其中以重度氟斑牙组的粘接强度最低。     

Effect of 2% chlorhexidine on dentin microtensile bond strengths and nanoleakage of luting cements

Objectives

The aim of this study was to investigate the effect of pre-treatment by chlorhexidine on the microtensile bond strength (mTBS) of resin cements and nanoleakage at the resin–dentine interfaces.

Methods

Cylindrical composite blocks were luted to human dentine using resin cements (RelyX ARC, 3M ESPE: ARC; Panavia F, Kuraray Medical Inc.: PF; RelyX Unicem, 3M ESPE: UN) with/without pre-treatment by 2% chlorhexidine digluconate (CAVITY CLEANSER, Bisco, Inc., Schaumburg, IL, USA). CAVITY CLEANSER was applied on the acid etched dentine for 60 s in the ARC group, and on smear layer-covered dentine in the PF and UN groups. After storage in water for 24 h, the bonded teeth were sectioned into 1 mm thick slabs and further into 0.9 mm × 0.9 mm beams. After immersion in water or ammoniacal silver nitrate for 24 h, the beams were stressed to failure in tension. The fractured surfaces were examined by field-emission scanning electron microscopy (FE-SEM) using backscattered electron mode. The silver-stained slabs were used to examine nanoleakage within the bonded interface by FE-SEM.

Results

The resin cement and chlorhexidine treatment had significant effects (p < 0.0001) on mTBS; while the storage media had no significant effect (p = 0.435). The mTBS of ARC was significantly higher than the other cements. Chlorhexidine reduced mTBS and produced pronounced nanoleakage when PF and UC were luted to dentine.

Conclusions

Pre-treatment with chlorhexidine affected the integrity of dentine bonding with PF and UC, while there was no adverse effect on coupling of ARC.     

干燥和湿润环境下不同牙本质粘接剂的微拉伸粘接强度比较

目的 应用6种不同类型牙本质粘接剂,比较其粘接试样在干燥和湿润测试环境下的微拉伸粘接强度,并分析产生差异的原因。方法 选择人离体无龋第三磨牙24颗,暴露面牙本质,将试样随机均分为6组,分别使用6种粘接剂（Prime ＆ Bond NT、Contax、Clearfil SE Bond、Adper Prompt、Clearfil S3 Bond和i Bond）和一种复合树脂制作牙本质-复合树脂粘接体,然后纵向片切制备横截面积约0.8 mm²的微拉伸试样,每种粘接材料的拉伸试样再分成3个亚组（每个亚组n=20）：A组（试样粘接界面保持湿润）、B组（试样在空气中干燥2 h后测试）、C组（试样在空气中干燥24 h后测试）,测试微拉伸粘接强度,最后扫描电镜观察断裂模式。结果 i Bond处理的A组与B、C组粘接强度差异无统计学意义（P>0.05）,其余5种粘接剂的A组粘接强度均低于B、C组（P<0.05）。断裂模式均以界面破坏为主,与试样干湿状态无关。结论 干燥环境下所测得牙本质粘接剂的微拉伸粘接强度值高于湿润环境下所测得的强度值。     

三种分层充填方法对牙本质黏结强度的影响

目的:对比研究3种分层充填方法对牙本质黏结的微拉伸强度的影响。方法:选取因正畸需要拔除的前磨牙15个,随机分为3组。去除面釉质,暴露平的牙本质表面,在其中央制备3.5mm×3.5mm×3mm的盒形洞。使用Single Bond黏结剂,按使用说明进行牙本质黏结,用Z100复合树脂充填窝洞:A组:分3层水平充填;B组:分3层斜向充填(第一层水平充填,第二、三层近远中向斜向充填);C组:分3层斜向充填(第一、二层近远中向斜向充填,;第三层水平充填)。用硬组织切片机将实验牙切成黏结面积约0.9mm×0.9mm的正方形小条作为试件,用以测试牙本质微拉伸黏结强度。在体视显微镜和扫描电镜下观察样本的断裂界面。结果:C组的微拉伸黏结强度测试值(31.99±5.27)高于A组(24.56±4.90)和B组(31.19±3.90),3种分层充填方法对牙本质微拉伸黏结强度的影响有统计学意义(P<0.05)。体视显微镜和扫描电镜下观察测试样本的断裂多数为黏结界面破坏。结论:3种分层充填方法对牙本质黏结的微拉伸强度存在影响,其中C组的分层充填方法略优于另外两组。因此,在修复较深的牙体缺损时,采用合适的分层充填方法有利于获得良好的黏结效果。     

Effect of surface conditioning methods on the microtensile bond strength of resin composite to composite after aging conditions.

OBJECTIVES: This study evaluated the effect of two different surface conditioning methods on the repair bond strength of a bis-GMA-adduct/bis-EMA/TEGDMA based resin composite after three aging conditions. METHODS: Thirty-six composite resin blocks (Esthet X, Dentsply) were prepared (5 mm x 6 mm x 6 mm) and randomly assigned into three groups for aging process: (a) immersion in citric acid (pH 3.0 at 37 degrees C, 1 week) (CA); (b) boiling in water for 8h (BW) and (c) thermocycling (x5000, 5-55 degrees C, dwell time: 30s) (TC). After aging, the blocks were assigned to one of the following surface conditioning methods: (1) silica coating (30 microm SiO(x)) (CoJet, 3M ESPE)+silane (ESPE-Sil) (CJ), (2) phosphoric acid+adhesive resin (Single Bond, 3M ESPE) (PA). Resin composite (Esthet.X) was bonded to the conditioned substrates incrementally and light polymerized. The experimental groups formed were as follows: Gr1:CA+PA; Gr2:CA+CJ; Gr3:BW+PA; Gr4: BW+CJ; Gr5:TC+PA; Gr6: TC+CJ. The specimens were sectioned in two axes (x and y) with a diamond disc under coolant irrigation in order to obtain non-trimmed bar specimens (sticks, 10 mm x 1 mm x 1 mm) with 1 mm(2) of bonding area. The microtensile test was accomplished in a universal testing machine (crosshead speed: 0.5 mm min(-1)). RESULTS: The means and standard deviations of bond strength (MPa+/-S.D.) per group were as follows: Gr1: 25.5+/-10.3; Gr2: 46.3+/-10.1; Gr3: 21.7+/-7.1; Gr4: 52.3+/-15.1; Gr5: 16.1+/-5.1; Gr6, 49.6+/-13.5. The silica coated groups showed significantly higher mean bond values after all three aging conditions (p<0.0001) (two-way ANOVA and Tukey tests, alpha=0.05). The interaction effect revealed significant influence of TC aging on both silica coated and acid etched groups compared to the other aging methods (p<0.032). Citric acid was the least aggressive aging medium. SIGNIFICANCE: Chairside silica coating and silanization provided higher resin-resin bond strength values compared to acid etching with phosphoric acid followed by adhesive resin applications. Thermocycling the composite substrates resulted in the lowest repair bond strength compared to citric acid challenge or boiling in water.