Effect of dentin conditioners on the microtensile bond strength of a conventional and a self-etching primer adhesive system.

OBJECTIVE: To investigate the effect of different dentin treatments on the microtensile bond strength of a self-etching primer and a simplified, total-etch adhesive system. METHODS: Flat dentin surfaces were created on extracted human third molars. The surfaces were treated with one of the following conditioners: self-etching primer for 20 s (Clearfil SE Primer), 37% phosphoric acid for 15 s or 0.5 M EDTA for 30 s. Conditioned surfaces were then bonded with either Clearfil SE Bond or Single Bond followed by resin composite (Z250) build-ups constructed incrementally. Application of SE Primer was included when Clearfil SE Bond was used, after phosphoric acid and EDTA conditioning. After 24 h storage in water at 37 degrees C, the teeth were longitudinally sectioned across the bonded interface to produce beams with 1.0 mm2 of adhesive area, tested with the microtensile method at a rate of 0.5 mm/min. Data were analyzed using two-way ANOVA and Tukey's test. RESULTS: The highest bond strength mean was found for the combination SE Primer/Single Bond (58.5+/-20.8 MPa), followed by the EDTA/Clearfil SE Bond (47.8+/-15.1 MPa) and phosphoric acid/Single Bond (40.9+/-14.3 MPa). The remaining combinations showed statistically similar (p>0.05) tensile bond strength. SIGNIFICANCE: The bond performance of the adhesives tested was dependent on the dentin conditioner. Pre-treatment with a mild etchant such as 0.5 M EDTA improved the bond strength of Clearfil SE Bond. Single Bond performed better when a self-etching primer was used as the dentin conditioner, probably by preventing the formation of a defective zone at the base of the hybrid layer. Overall results indicate that higher bond strengths can be achieved by conditioning dentin with milder etchants, suggesting that deeper demineralization may prevent proper resin infiltration, hence compromising the bond.     

The bond of resin to different dentin surface characteristics

This study investigated the effects of dentin surface characteristics on bond strengths between resin and dentin. The shear bond strengths mediated by two dentin adhesive systems (Clearfil SE Bond and OptiBond Solo Plus) were evaluated. For each material, flat dentin surfaces prepared from human upper premolars were allocated to eight groups according to three characterizations; dentin location (occlusal or cervical), dentin depth (superficial or deep) and dentinal tubule orientation (perpendicular or parallel). A 0.75-mm diameter area of dentin was bonded according to each manufacturer's instructions before placing 0.5-mm high resin composite. The bonds were stressed in shear at a crosshead speed of 1 mm/minute. The mean bond strengths were compared using ANOVA and independent t-test. No statistically significant differences were found in shear bond strengths based on dentin location. Clearfil SE Bond presented higher bond strengths to deep dentin specimens bonded perpendicular to the tubules compared to those that were bonded parallel to the tubules. Whereas, the opposite results were found for deep dentin specimens bonded with OptiBond Solo Plus. In the case of superficial dentin, there were no differences between the two materials when bond strengths were compared among the different orientations of tubule. The results indicated that shear bond strengths may be affected by dentin depth, orientation of the tubule and the bonding material used, but not by location of the dentin.     

Ultra-morphological characteristics of dentin surfaces after different preparations and treatments

Using transmission electron microscopy (TEM), this study investigated the characteristics of smear layers after preparation of dentin surfaces using different methods. In addition, this study analyzed, using scanning electron microscopy (SEM), the interactions of smear layers with the various acidic agents used subsequently to treat the dentin surface. Mid-coronal dentin surfaces were prepared according to one of five instrumentation methods: fracture; grinding with carbide bur; grinding with regular-grit diamond bur; grinding with superfine-grit diamond bur; or grinding with 600-grit silicon carbide (SiC) abrasive paper. Then, each prepared dentin surface was further divided into control (no further treatment) or treatment with one of the following agents: phosphoric acid solution (PAS); phosphoric acid gel (PAG); Clearfil SE Bond 2 Primer (SE2); or Scotchbond Universal Adhesive (SBU). Longitudinal ultra-thin sections were made for TEM observations. Dentin discs, representing each surface preparation and treatment method described above, were created, and the morphology was examined by SEM. The TEM results revealed differences in thickness and denseness of the smear layer, according to the different methods of instrumentation used to prepare the dentin surface. The two forms of phosphoric acid completely removed the smear layer in all groups. Agglomerated silica particles were observed on the top of the collagen layer after etching with PAG. For all dentin surfaces, except for that prepared with SiC, SE2 demonstrated better etching efficacy on different smear layers, whereas SBU provided only superficial interaction.     

Root and pulpal dentin after surface demineralization

Abstract Previous studies have indicated that there may be a difference in connective tissue response to surface demineralized dentin from root and pulpal surface regions. Consequently, it was the purpose of the present investigation to examine the initial surface characteristics of the dentin from these regions to determine if there were differences which could enhance interactions with adjacent connective tissues. Rectangular dentin specimens with opposite faces of root and pulpal region dentin were immersed in a saturated solution of citric acid, pH 1, for 3 min, rinsed, and prepared for examination in an ISI-40 SEM. Comparisons were made between root and pulpal surfaces of the specimens, and with non-acid treated controls. Control specimens were characterized by the presence of a smear layer which obscured the openings of dentinal tubules on all surfaces. Citric acid treatment removed the smear layer, resulted in exposure of dentinal tubule orifices, and produced a mat-like, fibrillar surface texture. The pulpal surface had a more coarse appearance than the root surface. Quantitation of the number and diameter of tubule orifices showed larger values for the pulpal surface. The percentage of die surface area occupied by tubule orifices was significantly greater on the pulpal aspect. It was concluded that surface demineralization of dentin from the pulpal region results in exposure of a greater amount of collagen substrate, and the latter may predestine an enhanced interaction with connective tissue components.     

Effect of dentin conditioning on dentin permeability and micro-shear bond strength

The purpose of this study was to compare fluid flow rates across dentin surfaces treated with four conditioners. The effect of conditioning on the micro-shear bond strengths of glass ionomer cement (Fuji IX GP) and resin-based adhesives (Single Bond 2 or Clearfil SE Bond) were also investigated. Under a simulated pressure of 1.3 kPa, two dentin conditioners, phosphoric acid, and a self-etching primer were applied to the dentin surfaces. Dentinal fluid flows at baseline and after conditioning were recorded for 15 min each. The conditioned surfaces were examined using a scanning electron microscope. The micro-shear bond strengths of the glass ionomer cement and of the resin-based adhesives bonded to conditioned dentin surfaces were evaluated while simulated intrapulpal pressure was maintained at 0 or 1.3 kPa. Only the dentin surface etched with phosphoric acid showed a significant increase in permeability. Micro-shear bond strengths of Fuji IX GP were not affected by conditioning the dentin surfaces or by bonding at different intrapulpal pressures (0 or 1.3 kPa). The effects on bond strengths of resin-based adhesives depended on the system used. The simulated positive intrapulpal pressure during bonding significantly affected the adherence of Single Bond 2, whereas Clearfil SE Bond was unaffected.     

Micro-tensile bond strengths of bonding agents to pulpal floor dentine

AIM: The purpose of this study was to characterize the dentine surface of the pulpal floor and to determine the micro-tensile bond strengths of two dentine adhesive systems used in conjunction with a resin composite core material to pulpal floor dentine. METHODOLOGY: Thirty-six extracted human molars were cut horizontally with a slow-speed diamond saw to expose the pulp chamber and the pulp tissue was removed. Eight teeth were used to investigate characteristics of untreated and etched dentine surfaces of the pulpal floor using SEM. Twenty-eight teeth were randomly allocated to two groups, each of 14 teeth. In group 1, a 'one-bottle' system (Prime & Bond NT) was used as dentine bonding agent and in group 2, a self-etching-priming system (Clearfil SE Bond) was applied. Pulp chambers of both groups were then filled with resin composite core buildup (FluoroCore) and kept moist in tap water at 37 degrees C for 24 h. Samples were prepared for micro-tensile bond testing by sectioning each tooth vertically in the mid-pulpal floor region and shaped to an hour-glass form of 1 +/- 0.2 mm(2) area at the bonded interface. Micro-tensile bond strengths were determined using a universal testing machine at a crosshead speed of 1 mm min-1. Fractured surfaces were examined by SEM. RESULTS: The intact pulpal floor showed numerous calcospherites with variable tubule density and few accessory canals. Etching the pulpal floor with 34% phosphoric acid gel resulted in an irregular surface with patent dentinal tubules and the dome-shaped calcospherites mostly lost. With self-etching primer, the superficial dentine surface was less demineralized and little peritubular dentine matrix was removed. Mean bond strength for the self-etching-priming (Clearfil SE Bond) specimens was significantly greater than for 'one-bottle' (Prime & Bond NT) specimens (P< 0.05, Student's t-test). The fracture mode of Clearfil SE Bond specimens was mostly partial cohesive failure within dentine, whilst Prime & Bond NT specimens mostly showed partial cohesive failure in bonding resin/composite. CONCLUSIONS: Despite an irregular surface morphology and absence of a smear layer, bonding to pulpal floor dentine was weaker than previously reported for cut coronal dentine. The self-etching-priming system bonded more strongly than the 'one-bottle' system.     

Effect of removal of surface collagen fibrils on resin-dentin bonding.

OBJECTIVES: The aim of this study was to evaluate the effects of NaOCl at removing the demineralized layer by examining the morphology of the hybrid layer and measuring shear bond strengths after different dentin treatments. METHODS: Dentin disks were treated with: (1) 35% phosphoric acid (PA) 20 s; (2) PA treatment followed by 1.5% NaOCl, 2 min; (3) PA treatment, followed by a 10% NaOCl immersion for 120 h. SEM was used to analyze the morphology of dentin and its interface with dentin bonding agents (DBAs), while shear bond strength tests were used to measure adhesion. All specimens were then fractured into two halves: One half was inspected under SEM; the other half was sequentially placed in 10% PA followed by 12.5% NaOCl for 70 h, to remove all dentin from the resin replica of the original bonded interface. RESULTS: SEM observations showed that collagen fibrils were completely removed from the acid-etched surface by NaOCl treatment. The diameter and the size of dentinal tubules and the number of lateral branches of the tubules were increased following NaOCl treatment. NaOCl applied on dentin smear layers did not significantly modify their SEM morphology. Resin tags were larger in diameter after phosphoric acid/NaOCl treatment than after only phosphoric acid treatment. Resin-infiltrated dentin-layers were only observed after the single phosphoric acid (i.e. conventional etching) procedure, and were not observed after combined phosphoric acid/NaOCl treatment. Etched/NaOCl samples showed a lower bond strength using Scotchbond MP and 3M Single Bond, but were higher in Optibond FL and unmodified in Prime & Bond 2.0 groups when compared with acid-etched controls. Treatment of etched dentin with NaOCl for 120 h produced an unusual type of resin infiltration of mineralized dentin that could be called a "reverse hybrid layer" which may explain the mechanism of resin bonding to NaOCl treated dentin. SIGNIFICANCE: The use of acidic conditioners for exposure of the collagen matrix exposes a soft delicate mesh that can collapse, thereby interfering with resin infiltration. If acid-etching is followed by NaOCl treatment, high bond strengths can be achieved via "reverse hybrid layer" formation, a proposed new mechanism of micromechanical resin retention. This mechanism is not yet recommended for clinical use but demonstrates a new type of resin retention.     

Effects of rotary instrumentation and different etchants on removal of smear layer on human dentin

STATEMENT OF PROBLEM: Various methods of rotary preparation and conditioning of teeth affect surface topography and may affect the retention of dental restorations. PURPOSE: This study microscopically evaluated dentin surfaces prepared by different rotary instruments and etched using several types of acid etchants that have been deemed suitable dentin conditioners. MATERIAL AND METHODS: Occlusal surfaces of 35 extracted human molars were ground wet with 320-grit silicon carbide paper to the depth of the central groove and then prepared with diamond (n = 5) and finishing burs (n = 30). Five specimens from each group were used for SEM evaluation of mechanical preparation effects. Dentin specimens (n = 5) prepared with finishing burs were then etched with 1 of 5 etchants (25% polyacrylic acid, 10% phosphoric acid, 10% citric acid, 20% lactic acid, or 32% phosphoric acid) for 10 seconds. Specimens were critical-point dried and freeze fractured for SEM analysis. RESULTS: Diamond rotary instruments created more undulating surfaces than finishing burs. Fine grooves were observed running perpendicular to undulations and parallel to the direction of instrument rotation. Specimens prepared with finishing burs exhibited a smooth surface interrupted by only a slight granularity. The amorphous smear layer was partially removed after the application of 25% polyacrylic acid (pH 1.53), but all dentinal tubules contained plugs. The number of dentin tubules containing plug material and the amount of material in the tubules decreased noticeably with 10% phosphoric acid (pH 0.86), and the dentin surface had an appearance similar to the specimen etched with 10% citric acid (pH 1.70). The surfaces treated with 20% lactic acid (pH 1.40) produced a clearly etched surface with minimal demineralization. Etching of dentin with 32% phosphoric acid (pH 0.16) revealed significant changes in dentin with the evidence of increased tubule diameter. CONCLUSION: Differences related to the method of instrumentation were found in the surface characteristics of dentin. The degree of smear layer removal was related to the pH of the acid etchant.     

羟磷灰石牙本质脱敏剂对温和型通用型粘接系统粘接性能研究

目的 本研究旨在评估含羟磷灰石（HA）脱敏剂封闭牙本质小管的效果及其对温和型通用型粘接剂粘接性能的影响。 方法 收集完整的第三磨牙,制备冠中部牙本质样本,建立牙本质敏感模型。根据不同的脱敏处理方式随机分为4组,分别进行下述处理：无脱敏处理（对照组）、Biorepair牙膏处理（含HA脱敏牙膏）、Dontodent牙膏处理（含HA脱敏牙膏）和HA糊剂处理。通过扫描电镜（SEM）观察牙本质小管封闭情况,并评估牙本质小管封闭率。分别使用All-Bond Universal、Single Bond Universal和Clearfil Universal Bond以自酸蚀模式应用于脱敏处理后的牙本质。通过接触角测量评估脱敏处理后牙本质表面的润湿性和表面能（SFE）。制备树脂-牙本质粘接试样,测试微拉伸粘接强度,分析脱敏处理方式对于3种通用型粘接剂的牙本质微拉伸粘接强度的影响。 结果 SEM显示含HA脱敏牙膏和HA脱敏剂处理后牙本质小管均明显封闭,封闭率HA组>Biorepair组>Dontodent组（P<0.05）。接触角分析表明,含HA脱敏剂对通用型粘接剂的润湿性无显著影响（P>0.05）,但脱敏处理后牙本质SFE显著增加（P<0.05）。微拉伸粘接强度测试表明,含HA脱敏牙膏会降低微拉伸粘接强度（P<0.05）,而HA组与对照组的微拉伸粘接强度之间差异无统计学意义（P>0.05）。 结论 含HA脱敏牙膏能够形成牙本质小管封闭。在使用温和型通用型粘接剂进行后续树脂修复时,含HA脱敏牙膏降低牙本质粘接强度,而HA糊剂的脱敏处理未对粘接性能产生不利影响。     

Dentinal tubule occlusion with lanthanum fluoride and powdered apatite glass ceramics in vitro

To simulate hypersensitive dentin, the smear layer and dentinal plugs of bovine root dentin specimens were removed by immersion in 10% phosphoric acid, polishing with hydroxyapatite particles, and ultrasonic cleansing. The fluoride-tannic acid-lanthanum-apatite (FTLA) group was treated with acidulated phosphate fluoride (APF) containing tannic acid followed by rubbing with a paste of lanthanum chloride (LaCl3) and powdered apatite glass ceramics. The treated specimens were immersed in a remineralizing solution that mimics saliva for 6 weeks. The SEM observations revealed that the treated surfaces of the FTLA group were completely covered with fine spherical compounds and the dentinal tubules were occluded with plugs to a depth of about 3 microns. Fluoride and lanthanum were detected to a depth of over 20 microns by EPMA observation. After the remineralization, the surface of FTLA-treated specimen did not have any opened tubules and showed a remarkable increase in the number of fine spherical deposits in the dentinal tubules. These results suggest that the reaction products produced by sequential treatment with acidic fluoride and LaCl3 and powdered apatite glass ceramics are able to effectively occlude dentinal tubules.     

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目的评价不同表面处理方法对激光预备牙本质形态学变化和黏结强度的影响。方法2013年5月至7月在中国医科大学附属口腔医院收集20～40岁新鲜拔除的活髓第三磨牙20颗及根尖发育完全的前磨牙8颗,铒、铬：钇钪镓石榴石（Er,Cr：YSGG）激光处理暴露的牙争面牙本质,然后按照不处理、37％磷酸酸蚀、自酸蚀及0．5mol／LEDTA调节各自分为4组,使用扫描电子显微镜（SEM）观察前磨牙牙本质处理面形态;第三磨牙使用Adper easy bond或Single bond 2黏结,Z350树脂逐层堆积树脂冠后,制作哑铃型试件进行微拉伸黏结强度测试,采用单因素方差分析进行组间差异比较。结果SEM观察发现：前磨牙激光预备后不处理组（对照组）牙面不规则,无玷污层,牙本质小管开放;磷酸酸蚀组牙本质表面最规则,自酸蚀组和EDTA处理组处理后表面变化不如磷酸酸蚀组明显。微拉仲黏结强度测试结果显示,第三磨牙分组后的3种处理方式牙本质黏结强度均显著高于对照组（P〈0．05）,磷酸酸蚀组黏结强度最强（P〈0．05）,而自酸蚀组及EDTA处理组差异无统计学意义（P〉0．05）。结论37％磷酸酸蚀、自酸蚀及0．5mol／LEDTA调节3种处理均可提高激光预备的牙本质黏结强度,37％磷酸酸蚀组获得最佳短期黏结效果。     

Shear bond strength of two resin cements to human root dentin using three dentin bonding agents

This study compared the bond strength of two resin cements to human root dentin when used with three bonding agents. The materials used were Rely X ARC and Perma Cem, two one-bottle bonding agents (Single Bond, Bond-1) and one self-etching bonding agent (Clearfil SE Bond). The dentin was obtained from single rooted human teeth, and the specimens were treated with either 15% EDTA or 37% phosphoric acid to remove the smear layer, except in groups where the self-etching bonding agent was used. The resin cements were placed on dentin surfaces with the use of bonding agents. Shear bond strength (SBS) was tested using a single plane shear test assembly. The dentin specimens were divided into 10 groups. Eight groups were pre-treated with EDTA or phosphoric acid to remove the smear layer, followed by a bonding agent (Bond-1 or Single Bond) and resin cement (Rely X or Perma Cem). In the two remaining groups, the smear layer was left intact, and the two resins cements were used in combination with the self-etching bonding agent (Clearfil SE Bond). No statistically significant differences were observed among the eight groups treated with one-bottle bonding agents. The mean bond strengths of the two groups treated with the self-etching bonding agent did not differ significantly from each other but were both significantly greater than the bond strengths of all the other groups. The results of this study also showed that EDTA can be used as an alternative to phosphoric acid in bonding procedures for resin cements. However, the bond strengths of resin cements, in combination with a self-etching bonding agent, were significantly greater than those of the same cements when used with one-bottle bonding agents.     

The in vitro morphological effects of some current pre-treatments on dentin surface: a SEM evaluation

This in vitro study morphologically evaluated the effect of some current surface pre-treatments on dentin, using scanning electron microscopy, and related these morphological alterations to clinical implications. The labial surfaces of 30 bovine lower incisors were ground to obtain a flat dentin surface and were finished with 600-grit SiC paper to produce standardized smear layers. The teeth were randomly divided into six groups of five each. Group 1 was the control group, smear layer covered dentin; Group 2 was etched with 37% phosphoric acid (PA) for 15 seconds; Group 3, 37% PA for 15 seconds, followed by 10% NaOCl for 60 seconds; Group 4, 10% NaOCl for 60 seconds; Group 5, a self-etching primer (Clearfil SE Bond, CSEB-primer) was applied for 20 seconds; Group 6, CSEB-primer for 20 seconds, followed by NaOCl for 60 seconds. The specimens were fixed, dehydrated, dried and analyzed by SEM. Treatment with 37% PA removed the smear layer, funneled the tubules and resulted in a collagen-rich surface which appeared to have collapsed in its outermost part, producing a dense surface layer covered with silica particles. When 37% PA treatment was followed by 10% NaOCl, the collagen network was removed to reveal an eroded, rough mineral surface with numerous lateral branches and larger than normal tubular orifices. The action of 10% NaOCl on the smear layer-covered dentin showed no significant alteration in surface morphology. The treatment with CSEB-primer dissolved the smear layer but only partially dissolved the smear plugs. The tubules did not present the typical funnel shape seen following PA treatment. These morphological aspects on dentin surface must influence bonding results. The dentin surface alterations produced by PA appeared to be a very severe demineralization pattern, quite irregular and less permeable to monomer infiltration, while the surface provided by the self-etching primer appeared to be a more uniform, less porous surface, and the association with simultaneous monomer infiltration may reduce the occurrence of mistakes in clinical bonding procedures.     

Aggressiveness of contemporary self-etching systems. I: Depth of penetration beyond dentin smear layers.

OBJECTIVE: This study examined, with the use of transmission electron microscopy (TEM), the aggressiveness of three self-etching adhesive systems in penetrating dentin smear layers of different thickness. METHODS: Dentin disks were produced from extracted human third molars. For the control group, the middle dentin surface was cryofractured to create a bonding surface that was devoid of a smear layer. The experimental teeth were polished with wet 600 or 60-grit SiC paper to produce bonding surfaces with thin and thick smear layers. They were bonded using one of the three self-etching systems: Clearfil Mega Bond (Kuraray), Non-Rinse Conditioner and Prime&Bond NT (Dentsply DeTrey) and Prompt L-Pop (ESPE). Bonded specimens were then demineralized and embedded in epoxy resin for TEM examination. RESULTS: For Mega Bond, thin authentic hybrid layers between 0.4-0.5 microm were found. Smear layer and smear plugs were retained as part of the hybridized complex. For Non-Rinse Conditioner/Prime&Bond NT, the authentic hybrid layers were between 1.2-2.2 microm thick. Smear layer and smear plugs were completely dissolved in dentin with thin smear layers, but were partially retained as part of the hybridized complex in those with thick smear layers. For Prompt L-Pop, authentic hybrid layers were 2.5-5 microm thick and smear layer and smear plugs were completely dissolved even in dentin with thick smear layers. SIGNIFICANCE: Contemporary self-etching systems may be classified as mild, moderate and aggressive based on their ability to penetrate dentin smear layers and their depth of demineralization into the subsurface dentin. The more aggressive system completely solubilized the smear layer and smear plugs and formed hybrid layers with a thickness approaching those of phosphoric acid conditioned dentin.     

Evaluation of residual dentin after conventional and chemomechanical caries removal using SEM

The purpose of this in vitro study was to analyze the residual dentinal surfaces following caries removal using rotatory instruments and two chemomechanical methods (Papacárie and Carisolv), by scanning electron microscopy (SEM). Thirty primary incisors were divided into three groups, according to the caries removal method used, and their residual dentin was examined under SEM (15). After caries removal, 15 of these teeth were restored with Single Bond (3M) adhesive system and Z100 Filtek composite resin (3M). The tags of the replicas were observed under SEM. The chemomechanical caries removal methods (Papacárie and Carisolv) formed an amorphous layer, similar to the smear layer and few exposed dentinal tubules; the conventional caries removal method produced a smooth and regular dentinal surface, with typical smear layer and exposed dentinal tubules. All groups showed abundant tag formation. Scanning electron microscopy analysis revealed a difference between dentin treated with rotatory instruments and that treated with chemomechanical methods in spite of the occurrence of a similar tag formation in both groups.     

Carisolv去龋对牙本质粘结界面影响的实验研究

目的:研究Carisolv去龋对牙本质粘结界面的影响。方法:24颗新鲜拔除的中度龋损的第三磨牙,随机分成ABCD4组。每个牙的龋洞分成两半,一半用Carisolv去龋,另一半用涡轮车针去龋后,做如下处理:A组不处理;B组320ml/L磷酸酸蚀,扫描电镜观察牙本质表面形态;C组不酸蚀,DyractAP复合体充填;D组320ml/L磷酸酸蚀后复合树脂充填,扫描电镜观察牙本质-充填体界面。结果:A组:Carisolv去龋后牙本质表面玷污层少,大部分牙本质小管口开放,清晰可见,表面粗糙不平;涡轮车针去龋后牙本质表面覆盖较厚玷污层,牙本质小管口堵塞,很少见到开口。B组:Carisolv去龋组和涡轮车针去龋组均去除了玷污层,牙本质小管口开放,但Carisolv组牙本质小管无管塞,而涡轮车针组牙本质小管残留部分管塞。C组:观察牙本质-复合体界面见Carisolv去龋组有较多树脂突形成,深入牙本质小管及管周;而涡轮车针去龋组未见明显树脂突起形成。D组:观察牙本质-树脂界面见2组树脂突的密度和长度无明显差异,但Carisolv去龋组树脂突之间的侧枝连接较涡轮车针去龋组多见。结论:Carisolv去龋后牙本质表面玷污层少,牙本质小管口开放,表面粗糙不规则,利于粘结,尤其在使用不需酸蚀的复合体充填时优势突出。     

A scanning electron microscopic and tensile bond strength evaluation of Gluma dentin bond application, as a function of dentinal pretreatment

Scanning Electron Micrographs (SEM) and Tensile Bond Strength (TBS) measurements were used to evaluate the influence of three different dentinal pretreatments. A new testing device was developed for the TBS measurements. Human tooth roots were ground with a diamond bur. Tap water, Gluma Cleanser, and Neo-Sabenyl-Tubulicid were used to clean the surfaces before SEM inspection. The adhesion between root dentin and Lumifor Composite restorations was mediated by Gluma Bond. SEM observations revealed that a 30-second application of Gluma Cleanser removes the smear layer totally. Neo-Sabenyl-Tubulicid produced a very smooth surface. Application of Gluma Bond did not alter this appearance. Mean TBS values for surfaces sprayed with tap water, Gluma Cleanser, and Neo-Sabenyl-Tubulicid were 10 MPa, 7.3 MPa, and 10 MPa, respectively. There was a significant difference between group 2 (Gluma Cleanser) and the other groups. From this in vitro study, it is concluded that total removal of the smear layer with opening of the dentinal tubules (e.g., by means of Gluma Cleanser) reduces the TBS of Gluma Dentin Bond-Lumifor restorations to ground root dentin.     

Effects of desensitizing agents on dentinal tubule occlusion

The aim of this study was to evaluate the features of dentinal tubules occlusion following application of three commercially available desensitizing agents: potassium oxalate-based / Oxa-Gel (OX), HEMA and glutaraldehyde-based / Gluma Desensitizer (GD) and acidulated phosphate fluoride-based / Nupro Gel (AF). Buccal cervical areas of twenty-four extracted human third molars were smoothed and wet-polished with SiC papers and diamond pastes, in order to simulate the clinical aspect of hypersensitive dentin cervical surfaces. The teeth were randomly divided into four groups (n=6), according to the dentin surface treatments: G1: untreated; G2: OX; G3: GD; G4: AF. Specimens were fractured in the lingual-buccal direction and prepared for SEM analysis. OX promoted tubule occlusion by crystal-like deposits in the lumen of the tubules. While GL created a thin layer over the dentin surface, AF application produced precipitates that occluded the tubules. According to the SEM analysis, all desensitizing agents were able to occlude the dentinal tubules.     

Microtensile bond strength of self-etching adhesive systems to differently prepared dentin

PURPOSE: To evaluate the microtensile bond strength (microTBS) of three self-etching adhesive systems with different degrees of acidity (Clearfil SE Bond, One-Up Bond F, and Xeno III) to dentin prepared with three different methods. METHODS: Forty-five extracted human third molars were ground flat to expose occlusal dentin and polished with 600-grit abrasive paper. All teeth were randomly divided into three groups according to the preparation method: baseline surface (AP#600), steel fissure bur (SB) and regular grit diamond bur (DB). Dentin surfaces were bonded with one of the three adhesive systems; then resin composite was incrementally built up. After storage in 37 degrees C water for 24 hours, specimens were cut and trimmed to create an hourglass shape with cross sectional area of approximate 1 mm2. All specimens were subjected to microtensile bond strength testing. The bond strength data were analyzed with one and two-way ANOVA and Dunnett Multiple comparisons test at P< 0.05. RESULTS: For Xeno III and One-Up Bond F, the microTBS to dentin prepared with the different methods were not significantly different. However, the microTBS of Clearfil SE Bond to dentin prepared with the diamond bur was significantly lower than the other preparation methods. Xeno III produced the lowest microTBS that were statistically different from the other adhesive systems when each preparation method was compared (P< 0.01). SEM observation of the prepared dentin surfaces showed that the diamond bur group produced a thicker smear layer that followed by steel bur and 600-grit paper. Therefore, the smear layer from diamond burs had a greater influence in decreasing microTBS of Clearfil SE Bond that has the weakest acidity self-etching adhesive systems evaluated.     

Effect of surface treatments and different adhesives on the hybrid layer thickness of non-carious cervical lesions

This in vitro study observed and compared the resin and non-carious sclerotic dentin interfaces generated by three different adhesives and two different techniques, using a scanning electron microscope (SEM). Thirty-two human premolars, with buccal, non-carious cervical lesions, were used. The teeth were randomly divided into eight groups. Group 1: Sclerotic dentin was treated with Single Bond (3M). Group 2: After superficial sclerotic dentin was removed with a diamond bur (Diatech, Coltene), the dentin surfaces were treated with Single Bond. Group 3: Sclerotic dentin was treated with Clearfil SE Bond (Kuraray). Group 4: After superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond was applied. Group 5: Sclerotic dentin was treated with Xeno III (Dentsply). Group 6: After superficial sclerotic dentin was removed with a bur, Xeno III was applied to the dentin surfaces. For Groups 7 and 8, after the superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond, with an additional 37% phosphoric acid gel, was used on the sclerotic dentin surfaces in Group 7 and Xeno III was used in Group 8. In all groups, the cavities were restored with Filtek Supreme (3M). All the specimens were sectioned longitudinally and polished along the cut surface. The sections were treated with 37% orthophosphoric acid for five seconds, rinsed with water and treated with 5% NaOCL for 10 minutes. The specimens were then gold-sputter coated and evaluated under SEM. The thickness of the hybrid layer was measured on the gingival, occlusal and axial dentin interfaces. ANOVA was performed to determine whether there were any statistically significant differences in hybrid layer thickness. Post-hoc multiple comparisons were done with Tukey's test. Hybrid layer thickness was increased with all adhesives when superficial dentin was removed with a bur. Hybrid layer thickness showed significant differences between total-etch and self-etch systems.