Human and bovine pulp-derived cell reactions to dental resin cements.

OBJECTIVES: The objective of this study was to evaluate the cytotoxic reaction of transfected human pulp derived cells (tHPDC) and transfected bovine pulp derived cells (tBPDC) after exposure to resin cements [RelyX UnicemClicker (RX), MaxCem (MC), Panavia F 2.0 (PF), BisCem (BC), and Bistite II DC (BII)] and to compare it to the generation of reactive oxygen species (ROS). MATERIALS AND METHODS: Set materials were extracted in culture medium, cell survival as a measure of cytotoxicity was determined photometrically using crystal violet after cells were exposed to the extracts for 24 h. The generation of ROS was detected by flow cytometry after cells were exposed to extract dilutions for 1 h. RESULTS: The ranking of the least to the most cytotoxic material was: RX < BII < PF < BC < MC for both cell lines, but for tHPDC, only MC and PF eluates were different from untreated controls. Generally, tBPDC were more susceptible to materials than tHPDC, but only for RX and BC was this difference statistically significant. All undiluted extracts increased ROS production in both cell lines but to a higher amount in tHPDC than in tBPDC. CONCLUSIONS: tHPDC reacted less sensitive than tBPDC in the cytotoxicity test but with the same rank order of materials. In contrast, the cellular oxidative stress reaction was more pronounced in tHPDC than in tBPDC. CLINICAL RELEVANCE: Depending on the residual dentine layer in deep cavities, biologically active resin monomers or additives released from resin cements may influence the dentine­pulp complex, for instance, its regenerative and reparative capacities.

Effect of a new restoration technique on fracture resistance of endodontically treated teeth.

The aim of the study was to investigate the effect of a new fiber-reinforced composite restoration technique on fracture resistance in endodontically treated premolars. Eighty sound extracted human mandibular premolars were assigned to four groups (n = 20). Group 1 did not receive any treatment. In groups 2, 3 and 4, the teeth received root canal treatment and a mesio-occluso-distal cavity preparation. Group 2 was kept unrestored. Group 3 was restored with a dentin bonding system and composite resin. In group 4, a piece of polyethylene ribbon fiber was inserted into the groove in a buccal to lingual direction during the restoration of teeth with dentin bonding system and composite resin. After finishing and polishing, the specimens were stored in 100% humidity at 37 degrees C for 24 h and placed at an angle of 45 degrees to the long axis of the tooth and subjected to compressive loading in a universal testing machine at a crosshead speed of 0.5 mm min(-1). The load necessary to fracture the samples was recorded in Newton (N) and submitted to Kruskal-Wallis anova and Mann-Whitney U-test. The fracture strength of the teeth reinforced with a combination of polyethylene fiber and composite resin were not significantly different than those that were restored with only composite resin (P > 0.05). However, most of the failure modes of the reinforced teeth were limited to the level of the enamel, while the other three groups showed fractures generally at the level of the dentin, cemento-enamel junction or more below (P < 0.05). Therefore, polyethylene ribbon fiber-reinforced composite resin restorations seemed a more reliable restorative technique than traditional composite restorations for extensive cavities.

Effects of citric acid modified with fluoride, nano-hydroxyapatite and casein on eroded enamel.

OBJECTIVES: The aim of this in vitro study was to evaluate the effects of citric acid containing fluoride, nano-hydroxyapatite, and casein on eroded enamel. DESIGN: The crowns of 120 extracted bovine incisors were embedded in acrylic resin. An enamel window (2 × 3 mm) was created on the surface. Before in vitro pellicle formation samples were eroded in 1% citric acid (pH = 3.2) for 1 h at 36 °C and were randomly classified to eight groups (n = 15) as follows: Positive control: 1% citric acid, Negative control: Distilled water, F1: 0.047 mmol/L sodium fluoride, F2: 0.071 mmol/L sodium fluoride, NHA1: %0.05 Nano-Hydroxyapatite, NHA2: %0.1 Nano-Hydroxyapatite, C1: %0.02 Casein, C2: %0.2 Casein. Erosion cycling was performed three times daily for 3 days. In each cycle, the samples were immersed in 10 mL of control or modified solutions (10 min) and in 10 mL of artificial saliva (60 min). The surface roughness and enamel loss were analyzed by using profilometer, scanning electron microscopy (SEM) and atomic force microscopy techniques (AFM). RESULTS: Among the groups, the positive control group was found to be having the highest erosive wear. Erosive wear in the F2, NHA2, C1, and C2 groups was not significantly different from the negative control group (p > 0.05). The C1 and C2 groups showed that erosion terminated and minimal tissue recovery occurred on the enamel surface. CONCLUSION: Although all modifications reduced further demineralization, the citric acid modification with casein was found to be having a greater impact on dental erosion than the others.

Effect of storage duration/solution on microshear bond strength of composite to enamel.

The aim of this study was to determine the effect of three storage solutions and two storage durations on microshear bond strength (microSBS) of a resin composite. Sixty non-carious human permanent molars were stored in three storage solutions (0.1% thymol, 10% formalin, and distilled water). Each tooth was separated mesio-distally into two parts. Specimens of the first part were stored for 24 hours, while specimens of the second part were stored for two months in the solutions. After each storage period, the enamel surface was covered with a composite resin in combination with an etch-rinse adhesive system. Specimens were then serially sectioned into sticks of 1 mm' bond area and subjected to microSBS test. There were no statistically significant differences between the two storage periods for each solution (p>0.05). The thymol solution group showed lower microSBS values than those of distilled water for both storage periods (p<0.05). As for the formalin group, its microSBS values were not statistically different from those of distilled water and thymol groups at each storage period (p>0.05). In conclusion, the thymol solution caused the microSBS of the resin composite to decrease when compared to both formalin and distilled water after 24 hours and two months. However, the microSBS of the resin composite was not affected by storage duration.

The quantitative evaluation of apical sealing of four endodontic sealers.

The aim of this in vitro study was to evaluate the apical seal obtained with four root canal sealers: Rocanal 2, Sealapex, AH Plus, and RC Sealer. Forty root canals were prepared using the step-back technique. The specimens were divided into four groups of 10 samples and obturated by laterally condensed gutta-percha with one of the tested sealers. The computerized fluid filtration method was used for evaluation of apical sealing properties. The quantitative apical leakage of each specimen was measured after 7, 14, and 21 days. Statistical analysis indicated that the apical leakage of all sealers used in this study decreased gradually from 7 days to 21 days (p < 0.05). Sealapex showed better apical sealing than the other sealers at 7, 14, and 21 days (p < 0.05). RC Sealer, AH Plus, and Rocanal 2 showed similar apical leakage values at every period (p > 0.05).

Shear bond strengths of self-etching adhesives to caries-affected dentin on the gingival wall.

The purpose of this study was to evaluate the bonding ability of five current self-etching adhesives to caries-affected dentin on the gingival wall. Seventy extracted human molars with approximal dentin caries were employed in this study. In order to obtain caries-affected dentin on the gingival wall, grinding was performed under running water. Following which, specimens mounted in acrylic blocks and composite resins of the bonding systems were bonded to dentin with plastic rings and then debonded by shear bond strength. With Clearfil SE Bond, bonding to caries-affected dentin showed the highest bond strength. With Optibond Solo Plus Self-Etch, bonding to caries-affected dentin showed higher shear bond strength than AQ Bond, Tyrian SPE & One-Step Plus, and Prompt-L-Pop (p<0.05). Further, the bond strengths of Clearfil SE Bond and Optibond Solo Plus Self-Etch to sound dentin were higher than those of Prompt-L-Pop, AQ Bond, and Tyrian SPE & One-Step Plus (p<0.05). In conclusion, besides micromechanical interlocking through hybrid layer formation, bond strength of self-etch adhesives to dentin may be increased from additional chemical interaction between the functional monomer and residual hydroxyapatite. The results of this study confirmed that differences in bond strength among self-etching adhesives to both caries-affected and sound dentin were due to chemical composition rather than acidity.

Apical leakage of resin based root canal sealers with a new computerized fluid filtration meter.

In this in vitro study, the apical leakage of three root-canal sealers: AH Plus, Diaket, and EndoREZ was evaluated using a new computerized fluid filtration meter. Forty-five extracted human premolar teeth with single root and canal were used. The coronal part of each tooth was removed and the root canals were prepared using GT Rotary files and crown-down technique. The roots were randomly divided into three groups of 15 samples, filled with one of the test materials and gutta-percha cones by the cold lateral condensation technique and were stored at 37 degrees C and 100% humidity for 7 days. One-week later, apical parts of roots of 10 +/- 0.05 mm were attached to computerized fluid filtration meter. Apical leakage quantity was determined as microl/cmH(2)O/min(-1). Statistical analysis indicated that root fillings with Diaket in combination with cold lateral condensation technique showed lower apical leakage than the others (p < 0.05). In addition, this new computerized fluid filtration meter allowed quantitative measurement of leakage easily. As it is a newly developed device to measure apical leakage of endodontic sealers, the reliability of it needed to be tested.

Microtensile bond strength of two resin composite materials placed with direct and indirect techniques under simulated pulpal pressure.

PURPOSE: The aim of this in vitro study was to compare the dentin bond strength of directly and indirectly inserted composite restorations. MATERIALS AND METHODS: Twenty extracted human mandibular molars were prepared to form a flat occlusal dentin surface using an Isomet saw under water. Five-mm-thick composite restorations (Filtek Z 250 and Clearfil AP-X) were placed on the dentin surfaces by direct or indirect techniques. The direct restorations were bonded with Single Bond and Clearfil SE Bond bonding agents. Indirect restorations were cemented with two composite luting cements (3M Opal Luting Cement and Panavia F). All restorative procedures were applied under simulated pulpal pressure (15 cm H2O). Each tooth was then vertically sectioned with an Isomet saw through the composite buildups and the dentin. Thus, for microtensile testing, 0.65 x 0.65 mm specimens were obtained from pulpal and remote dentin regions. The results were analyzed according to the regional dentinal surfaces (pulpal and remote dentin). For statistical analyses, two-way ANOVA and Duncan post-hoc tests were used (p < 0.05). RESULTS: Direct application of Clearfil AP-X showed that tensile bond strengths were higher than those obtained for directly and indirectly applied Filtek Z 250 and indirectly applied Clearfil AP-X. No significant difference in tensile bond strengths was demonstrated between pulpal and remote dentin (p > 0.05). CONCLUSION: It is concluded that the bond strengths of resin luting cements to dentin need further improvement.

Effect of tooth age on microtensile bond strength of two fluoride-releasing bonding agents.

PURPOSE: The purpose of this study was to evaluate the effect of age of dentin and enamel on the microtensile bond strengths of a glass-ionomer based, all-in-one, single-step, self-etching adhesive system (Reactmer Bond, RB) and an antibacterial, two-step self-etching primer system (ABF Bond, ABF). MATERIALS AND METHODS: Extracted molars from 3 age groups (20 to 25, 35 to 40, and 50 to 55 years) were used. Enamel was removed from the occlusal surfaces of the teeth, and the entire flat surfaces were covered with composite resin (4 mm in height) following application of bonding agents. The bonded specimens were thinly sectioned parallel to the long axis of the tooth into 0.87 +/- 0.03 mm2 rectangular sections, resulting in 6 to 7 enamel specimens and 10 to 15 dentin specimens per tooth. The specimens were subjected to the microtensile test at a crosshead speed of 1 mm/min. The data were analyzed by Univariate ANOVA, Tukey HSD, and regression analysis. RESULTS: The bond strength of ABF to both enamel and dentin was higher than the bond strength of RB. Bond strengths of ABF to dentin were significantly higher than the bond strengths to enamel (p < 0.05). The 35- to 40-year age group of ABF showed the highest bond strength of all. In RB dentin groups, 34% of specimens showed cohesive failure in composite resin material. CONCLUSION: Bond strength values to enamel were not affected by age of teeth in either bonding system. Dentinal bond strength using ABF changed according to age of the teeth. Age did not affect bond strength values of RB to dental hard tissues. However, the high number of cohesive failures in Reactmer paste indicated low tensile strength of the material.

Effect of desensitizers on the bond strength of a self-etching adhesive system to caries-affected dentin on the gingival wall.

A self-etching dentin adhesive was evaluated for its ability to bond to caries-affected and sound dentin after applying three desensitizers to the gingival walls. Sixty extracted human molars, with approximal dentin caries, were cut horizontally on the long axis of the tooth through caries-affected gingival walls. Carious dentin was removed with SiC paper by means of a caries detector to expose caries-affected dentin. The molars were randomly assigned to four groups: control and three experimental groups-Micro Prime, Glauma Desentizer and Cervitec. Desensitizers were applied to the dentinal surfaces according to manufacturers' instructions. A resin composite was bonded to both the caries-affected and sound dentin of each tooth using a bonding system and plastic rings. The restoration was debonded by shear bond strength. The application of Micro Prime and Gluma Desensitizer to caries-affected dentin did not show any effect on bond strength testing. However, Cervitec caused a decrease in bond strength to caries-affected dentin. The effect of desensitizers on the bond strength of the self-etch bonding agent to caries-affected dentin changed according to the chemical composition of the materials. Desensitizer application on sound dentin is recommended with self-etch bonding systems.

Effects of chlorhexidine and povidone-iodine mouth rinses on the bond strength of an orthodontic composite.

The purpose of this study was to determine whether the application of two antibacterial mouth rinses to etched and unetched enamel affects the shear bond strength (SBS) of an orthodontic composite resin. Eighty-five lower human incisors were divided into five groups, ie, group 1: control group, no mouth rinse was used; groups 2 and 3: mouth rinses were applied to the intact enamel surface before etching; groups 4 and 5: mouth rinses were applied to the etched enamel. A bonding agent and a composite resin were applied to the teeth surface. For shear bond testing, the specimens were mounted in a universal testing machine, and an apparatus attached to a compression load cell was applied to each specimen until failure occurred. The data were analyzed using analysis of variance and Tukey honestly significance tests. Fracture modes were analyzed by Mann-Whitney U-test. There was no statistically significant difference between the SBS values of group 1 (31.64 +/- 3.62 MPa) and group 4-five experimental applications (P > or = .05). However, the SBS value of group 3 (36.56 +/- 5.95 MPa) was significantly larger than those of group 4 (30.00 +/- 4.97 MPa) and group 5 (30.26 +/- 7.30 MPa). In addition, no significant differences were observed between group 1 and groups 2 (34.33 +/- 7.26 MPa) and 3 (36.56 +/- 5.95 MPa) (P > or = .05). Because the application of chlorhexidine and povidone-iodine before acid etching did not cause any decrease in bond strength, it is advisable for use under the orthodontic resin composite to obtain an antibacterial effect or to prevent the risk of bacteremia.

Cytotoxicity evaluation of luting resin cements on bovine dental pulp-derived cells (bDPCs) by real-time cell analysis.

To evaluate the cytotoxicity of resin cements on dental pulp-derived cells (bDPCs), Bifix QM (BQM), Choice 2(C2), RelyX U200(RU200), Maxcem Elite(ME), and Multilink Automix(MA) were tested. The materials were incubated in DMEM for 72 h. A real-time cell analyzer was used to evaluate cell survival. The statistical analyses used were one-way ANOVA and Tukey-Kramer tests. BQM, RU200, and ME demonstrated a significant decrease in the bDPCs' index at 24 and 72 h (p≤0.001). These materials were found to be the most toxic resin cements, as compared to the control and other tested materials (C2 and MA). However, C2 and MA showed a better survival rate, compared to BQM, RU200, and ME, and had lower cell index than the control group. The cytotoxic effects of resin cements on pulpa should be evaluated during the selection of proper cements.

Cytotoxicity of temporary cements on bovine dental pulp-derived cells (bDPCs) using realtime cell analysis.

PURPOSE: To evaluate the cytotoxicity of temporary luting cements on bovine dental pulp-derived cells (bDPCs). MATERIALS AND METHODS: Four different temporary cements were tested: Rely X Temp E (3M ESPE), Ultratemp (Ultradent), GC Fuji Temp (GC), and Rely X Temp NE (3M ESPE). The materials were prepared as discs and incubated in Dulbecco's modified eagle's culture medium (DMEM) for 72 hours according to ISO 10993-5. A real-time cell analyzer was used to determine cell vitality. After seeding 200 µL of the cell suspensions into the wells of a 96-well plate, the bDPCs were cured with bioactive components released by the test materials and observed every 15 minutes for 98 hours. One-way ANOVA and Tukey-Kramer tests were used to analyze the results of the proliferation experiments. RESULTS: All tested temporary cements showed significant decreases in the bDPCs index. Rely X Temp E, GC Fuji Temp, and Rely X Temp NE were severely toxic at both time points (24 and 72 hours) (P<.001). When the cells were exposed to media by Ultratemp, the cell viability was similar to that of the control at 24 hours (P>.05); however, the cell viability was significantly reduced at 72 hours (P<.001). Light and scanning electron microscopy examination confirmed these results. CONCLUSION: The cytotoxic effects of temporary cements on pulpal tissue should be evaluated when choosing cement for luting provisional restorations.

Restoring function and esthetics in a patient with amelogenesis imperfecta: a case report.

Amelogenesis imperfecta is a hereditary disorder that affects enamel on primary and permanent teeth. It is a rare dental disease but represents a major restorative challenge for the dentist. A 14-year-old boy presented with sensitive, discolored, and mutilated teeth and a decreased vertical dimension of occlusion. The aim of treatment was to reduce dental sensitivity, to restore esthetics, and to correct the vertical dimension of occlusion. To modify the occlusion, and to protect the dentin from chemical and thermal attacks, nickel-chrome onlays were placed on the molars. To improve the esthetics of the incisors and premolars, resin composite restorations were applied. The patient was regularly recalled during the postoperative period. Radiographic and clinical examinations 10 months posttreatment revealed no evidence of disorders associated with the restored teeth or their supporting structures.

Evaluation of the dental plaque pH recovery effect of a xylitol lozenge on patients with fixed orthodontic appliances.

The purpose of this study was to evaluate the influence of a xylitol lozenge on the dental plaque pH profile of fixed orthodontic patients. Twelve volunteers participated in this study. Before the measurement of plaque pH, subjects were asked to refrain from brushing their teeth for 48 hours and from eating and drinking for two hours. The subjects' baseline dental plaque pH was recorded using the touch technique. It was followed by a one-minute rinse with 15 ml of a 10% solution of sucrose, and subsequent plaque pH measurements were carried out during the next one hour. Xylitol lozenges were taken five times a day during a 14-day period. The variables of resting-plaque pH, minimum-plaque pH (MP pH), time required to reach MP pH (TMP), last-plaque (LP) pH at the end of one hour, cH area (CH), and pH at each test time were calculated for each pH test of the subjects. The paired sample t-test was used for statistical comparison. The mean MP pH values increased from 4.81 to 5.09 in the experimental measurement (P < .05). The mean TMP was not affected by the use of xylitol (P > .05). Although the LP pH showed an increase during the experimental period, the difference between control and experimental periods was not statistically significant (P > .05). The CH of the experimental period was significantly less than that of the control period (P < .05). As a result, the use of a xylitol lozenge after a sucrose challenge can be an advisable practice for fixed orthodontic patients to prevent future dental caries.

Dental approach to erosive tooth wear in gastroesophageal reflux disease.

BACKGROUND: The duration of gastro-esophageal reflux disease (GERD), the frequency of reflux, the pH and type of acid, and the quality and quantity of saliva affect the severity of dental erosion due to GERD. OBJECTIVE: To summarize the diagnostic protocol and treatment of dental erosion due to GERD. METHODS: A Medline literature search was performed to identify articles associated with a dental approach to GERD. RESULTS: The dental professional must carry out a diagnostic protocol, which includes collecting data on the patient's medical and dietary history, occupational/recreational history, dental history, and oral hygiene methods. Intraoral, head and neck, and salivary function examinations should be performed to expose the dental implications of GERD symptoms. CONCLUSION: Diagnosing the cause of erosive tooth wear can help prevent further damage. Patients must be informed about how to prevent GERD.

Effect of accelerated aging on the bonding performance of fluoridated adhesive resins.

The purpose of this study was to investigate the dentin bond durability of a one-step, fluoride-containing, glass ionomer-based adhesive system, Reactmer Bond (RB), and that of a two-step, fluoride-containing, self-etch adhesive system, Clearfil Protect Bond (CPB). Enamel was removed from the occlusal surfaces of teeth, and flat dentin surfaces were entirely covered with a composite resin following the application of an adhesive material (n=10). After specimens were sectioned into rectangular sticks of 0.87 ± 0.03 mm(2), the sticks were randomly assigned into two accelerated aging time period groups: 1 week or 1 year. Microtensile bond strengths were determined. Bond strength of RB increased significantly after 1 year (1 week=27.80 ± 10.57 MPa versus 1 year=36.93 ± 14.38 MPa) (p<0.05). In contrast, there was no significant difference in bond strength between the two time periods for CPB (1 week=51.74 ± 17.8 MPa versus 1 year=56.03 ± 18.85 MPa) (p>0.05). Both fluoride-containing adhesives seemed to demonstrate reliable bonding performance after 1 year of accelerated aging in water.

Cytotoxicity testing of temporary luting cements with two- and three-dimensional cultures of bovine dental pulp-derived cells.

This study evaluated the cytotoxicity of eugenol-containing and eugenol-free temporary luting cements. For cytotoxicity testing, bovine pulp-derived cells transfected with Simian virus 40 Large T antigen were exposed to extracts of eugenol-containing (Rely X Temp E) and eugenol-free (Provicol, PreVISION CEM, and Rely X Temp NE) temporary luting cements for 24 h. The cytotoxicity of the same materials was also evaluated in a dentin barrier test device using three-dimensional cell cultures of bovine pulp-derived cells. The results of the cytotoxicity studies with two-dimensional cultures of bovine dental pulp-derived cells revealed that cell survival with the extracts of Rely X Temp E, Provicol, PreVISION CEM, and Rely X Temp NE was 89.1%, 84.9%, 92.3%, and 66.8%, respectively. Rely X Temp NE and Provicol showed cytotoxic effects on bovine dental pulp-derived cells (P < 0.05). The results of the dentin barrier test revealed that cell survival with the above-mentioned temporary cement was 101.5%, 91.9%, 93.5%, and 90.6%, respectively. None of the temporary luting cements significantly reduced cell survival compared with the negative control in the dentin barrier test (P > 0.05). Biologically active materials released from temporary luting cements may not influence the dentine-pulp complex if the residual dentine layer is at least 0.5 mm thick.

Cytotoxicity evaluation of dentin bonding agents by dentin barrier test on 3-dimensional pulp cells.

OBJECTIVE: The aim of this study was to evaluate the effects of 4 dentin-bonding agents on the cell viability of bovine derived cells. STUDY DESIGN: Cytotoxicity of dentin-bonding agents (G-Bond [GB], Adper Prompt Self-Etch [APSE], Clearfil DC Bond System [CDCB], and Quadrant University-1-Bond [UB]) was analyzed with a dentin barrier test device using 3-dimensional (3D) pulp cell cultures. A commercially available cell culture perfusion chamber was separated into 2 compartments using a 500 µm dentin disk. The 3D cultures were placed on a dentin disk and held in place with a special biocompatible stainless steel holder. Test materials were introduced into the upper compartment in direct contact with the cavity side of the dentin disks according to the manufacturer's instructions. Subsequently, the pulpal part of the perfusion chamber containing the cell cultures was perfused with a medium (2 mL/h). After an exposure period of 24 hours, cell survival was determined by using the MTT assay. Statistical analyses were performed using the Mann-Whitney U test. RESULTS: In the dentin barrier test, cell survival rates of UB and CDCB were similar to the control group (P > .05). However, all other tested materials were cytotoxic for the 3D pulp-derived cell cultures (P < .05). CONCLUSIONS: Dentin-bonding agents include biologically active ingredients and may modify pulp cell metabolism when the materials are used in deep cavities in spite of a dentin barrier. If these adhesive agents are used in deep cavities, a biocompatible cavity liner should be used.

Effect of artificial aging regimens on the performance of self-etching adhesives.

This in vitro study was performed to compare the microtensile bond strengths (MTBS) of current self-etching adhesives to dentin and to evaluate the effects of artificial aging [(thermocycling (TC) and/or mechanic loading (ML)] on MTBS and on nanoleakage of self-etching adhesives. Two-step (AdheSE Bond, Clearfil Protect Bond, Clearfil SE Bond, Optibond Self-Etch) and one-step (Hybrid Bond, G-bond, Clearfil Tri-S Bond, and Adper Prompt L-Pop) self-etching adhesives were tested. Resin composite build-ups were created, and the specimens were subjected to 10(4) TC, 10(5) ML, and 10(4)/10(5) TC/ML. Non-aged specimens served as controls. In the control group, no significant differences were found among the MTBS of the one-step self-etching adhesives and among those of three two-step self-etching adhesives (AdheSE Bond, Clearfil Protect Bond, and Clearfil SE Bond) (p > 0.05). The MTBS of AdheSE Bond and Clearfil Protect Bond were higher than were those of all one-step self-etching adhesives and than those of Optibond Self-Etch. The MTBS of Clearfil SE Bond was higher than were those of two one-step self-etching adhesives (Adper Prompt L-Pop, G-bond) (p < 0.05). Compared with the non-aged controls, TC did not decrease (p > 0.05), but ML and TC/ML significantly decreased the MTBS of the adhesives tested (p < 0.05). Two-step self-etching adhesives tended to fail more cohesively in dentin. Transmission electron microscopy revealed different nanoleakage patterns in the adhesive and hybrid layers of all adhesives examined, and signs of additional silver-filled water channels were more readily detectable after TC/ML.