Cytotoxicity,genotoxicity and antibiofilm activity on Streptococcus mutans of an experimental self-etching adhesive system containing natural Butia capitata oil

This study evaluated the biocompatibility and antibiofilm effects on Streptococcus mutans of an experimental self-etching adhesive system formulated with a natural vegetable product. The cytotoxicity of Clearfil Protect Bond (CPB), Clearfil SE Bond (CSEB), Adper SE Plus (AP), an experimental adhesive containing Butia capitata oil (EA) and an oil-free experimental adhesive as control (CA) was tested on 3T3/NIH mouse fibroblasts. Genotoxicity was indicated by micronuclei formation, and cell alterations were analyzed using light microscopy. To evaluate the effect of the adhesives on S. mutans biofilm, biomass samples were collected for dry weight and bacterial viability analyses, and the pH of the culture media was determined daily as an indicator of biofilm acidogenicity. The CA primer and EA uncured bond adhesive were the least toxic. No statistical difference was observed between EA and the untreated control, and EA showed similar effect to CPB. These findings suggest EA is biocompatible and presents activity against S. mutans biofilm.     

Effect of irradiation source on the dentin bond strength of a one-bottle universal adhesive containing an amide monomer

One-bottle universal adhesives have been widely used because of their simplicity of bonding procedures for various dental materials. The present study evaluated the effect of the polymerization light source on the micro-tensile bond strengths of a universal adhesive (Clearfil Universal Bond Quick) to dentin in comparison with a one-bottle self-etch adhesive (Clearfil S³ Bond Plus) and two 2-step self-etch adhesives (Clearfil SE Bond and Clearfil SE Bond 2). The adhesives were applied to extracted human dentin according to the manufacturer’s instructions and irradiated using either a quartz-tungsten-halogen (QTH) or blue light-emitting diode (LED). Subsequently, a resin composite was incrementally built on each adhesive and light-cured using the QTH. The bonded specimens were sectioned and subjected to micro-tensile bond strength tests. Both the type of adhesive and the light source were found to statistically affect the bond strength, with no interactions. The LED gave greater bond strength than the QTH. The bond strengths of the two-step adhesives were significantly higher than those of the one-bottle products, irrespective of the light source. The Clearfil Universal Bond Quick exhibited significantly higher bond strength than the Clearfil S³ Bond Plus. LED curing improved the performance of Clearfil Universal Bond Quick, and this product generated bond strength superior to that of the existing one-bottle adhesive Clearfil S³ Bond Plus.     

Microshear bond strength of universal adhesives for use with artificially demineralized enamel,with and without pre-etching

The aim of this study was to investigate the microshear bond strength of five universal adhesives for use with demineralized enamel, with and without pre-etching. Using five universal adhesives (Single Bond Universal (SBU), Clearfil Universal (CU), Prime&Bond Elect Universal (PBU), Bisco All Bond Universal (ABU), Gluma Bond Universal (GU)), composite cylinders were bonded to the labial surfaces of extracted upper incisor teeth, with or without pre-etching. A micro-shear bond strength test was performed. The debonding surfaces were evaluated with the use of SEM. The data was analyzed using one-way ANOVA and Tukey’s Post-hoc tests. SBU, ABU, and PBU increased the bond strength statistically when used in etch&rinse mode (p?<?0.05). GU and CU did not change the bond strength statistically with the use of pre-etching (p?>?0.05). The bond strength of universal adhesives on demineralized enamel, with and without initial acid etching, depends on the type of adhesive system used.     

Antibacterial Effect of Dental Adhesive Containing Dimethylaminododecyl Methacrylate on the Development of Streptococcus mutans Biofilm

Antibacterial bonding agents and composites containing dimethylaminododecyl methacrylate (DMADDM) have been recently developed. The objectives of this study were to investigate the antibacterial effect of novel adhesives containing different mass fractions of DMADDM on Streptococcus mutans (S. mutans) biofilm at different developmental stages. Different mass fractions of DMADDM were incorporated into adhesives and S. mutans biofilm at different developmetal stages were analyzed by MTT assays, lactic acid measurement, confocal laser scanning microscopy and scanning electron microscopy observations. Exopolysaccharides (EPS) staining was used to analyze the inhibitory effect of DMADDM on the biofilm extracellular matrix. Dentin microtensile strengths were also measured. Cured adhesives containing DMADDM could greatly reduce metabolic activity and lactic acid production during the development of S. mutans biofilms (p < 0.05). In earlier stages of biofilm development, there were no significant differences of inhibitory effects between the 2.5% DMADDM and 5% DMADDM group. However, after 72 h, the anti-biofilm effects of adhesives containing 5% DMADDM were significantly stronger than any other group. Incorporation of DMADDM into adhesive did not adversely affect dentin bond strength. In conclusion, adhesives containing DMADDM inhibited the growth, lactic acid production and EPS metabolism of S. mutans biofilm at different stages, with no adverse effect on its dentin adhesive bond strength. The bonding agents have the potential to control dental biofilms and combat tooth decay, and DMADDM is promising for use in a wide range of dental adhesive systems and restoratives.     

Antibacterial Photodynamic Inactivation of Fagopyrin F from Tartary Buckwheat (Fagopyrum tataricum) Flower against Streptococcus mutans and Its Biofilm

The objective of this study was to determine reactive oxygen species (ROS) produced by fagopyrin F-rich fraction (FFF) separated from Tartary buckwheat flower extract exposed to lights and to investigate its antibacterial photodynamic inactivation (PDI) against Streptococcus mutans and its biofilm. ROS producing mechanisms involving FFF with light exposure were determined using a spectrophotometer and a fluorometer. S. mutans and its biofilm inactivation after PDI treatment of FFF using blue light (BL; 450 nm) were determined by plate count method and crystal violet assay, respectively. The biofilm destruction by ROS produced from FFF after exposure to BL was visualized using confocal laser scanning microscopy (CLSM) and field emission scanning electron microscope (FE-SEM). BL among 3 light sources produced type 1 ROS the most when applying FFF as a photosensitizer. FFF exposed to BL (5 and 10 J/cm²) significantly more inhibited S. mutans viability and biofilm formation than FFF without the light exposure (p < 0.05). In the PDI of FFF exposed to BL (10 J/cm²), an apparent destruction of S. mutans and its biofilm were observed by the CLSM and FE-SEM. Antibacterial PDI effect of FFF was determined for the first time in this study.     

In vitro Streptococcus mutans biofilm formation on surfaces of chlorhexidine-containing dentin bonding systems

This in vitro study evaluated the influence of chlorhexidine diacetate (CDA) when blended within dentin bonding systems (DBSs) on Streptococcus mutans (S. mutans) biofilm formation.One commercially available 0.2% wt CDA-containing DBS (Peak Universal Bond) and five experimental 0.2% wt CDA-containing DBS formulations (experimental Adper Scotchbond 1XT plus experimental resins, R₂, R₃, R₄, R₅) were assessed vs their no-CDA containing counterparts. Twenty-eight DBSs disks were prepared for each group (6.4 mm×1.0 mm) and cured for 80 s at 800 mW/cm² in a nitrogen atmosphere. A modified Drip-Flow Reactor was used to grow S. mutans biofilms on specimen surfaces for 24 h and adherent, viable biomass was evaluated using a tetrazolium salt assay (MTT). Two specimens from each of the tested materials were processed with LIVE/DEAD stain and observed using laser confocal microscopy (CLSM) while two disks from each group were examined by using scanning electron microscopy (SEM).MTT assay, CLSM and SEM observations showed that CDA addition decreased, increased or did not change S. mutans biofilm formation. The lowest biofilm formation was obtained with Peak Universal Bond and R₅ (with and without CDA).It may be concluded that the chemical composition of DBSs determines their ability to promote or hamper biofilm formation. Therefore, CDA addition may be helpful in modulating biofilm formation provided that DBS formulation is tuned and optimized.     

The effects of self-etch bio-active dental adhesive systems on bacterial microleakage

The aim of this in vitro study was to evaluate the effects of bio-active and non-bio-active self-etch adhesive sytems on bacterial microleakage of class II box cavities with restoration margins in dentin. Two bio-active (Clearfil Protect Bond and F1 Bond II) and two nonbio-active (Clearfil SE Bond and Clearfil s3 Bond) adhesive systems were selected for the study. Eighty mesial and distal class II box cavities were prepared on fourty sound human third molar teeth. The teeth were then divided into four groups with 10 teeth in each group. Groups were restorated using different adhesive systems. The restored specimens were immersed into a culture medium containing streptococcus mutans for bacterial microleakage test. Serial sections of the specimens were used to evaluate the bacterial lekage by using light microscope. The data obtained from the test of bacterial microleakage was evaluated using 2-way mixed analysis of variance (p < 0.05). Statistical analysis showed significant differences between the groups (p < 0.05). Nevertheless it was observed that none of the tested adhesive systems including the bio-active ones were successfull in eliminating bacterial microleakage.     

Effect of hydroxyapatite morphology and quaternary ammonium polymer co-inclusion on bond strength,cytotoxicity, and cell morphology of self-etching adhesive

This study aimed to obtain and evaluate hydroxyapatites (HAp) as nanoparticles and nanorods for use in self-etching adhesive. The effect of co-inclusion of a multifunctional quaternary ammonium methacrylate polymer (QAMP) on their mechanical, cell viability, and morphological properties was also investigated. Hydroxyapatite nanoparticles (HApP24 and HApP36) and nanorod-shaped hydroxyapatite (HApR14) were characterized by XRPD, SEM-FEG, and FTIR spectroscopy. HApP24, HApP36, HApR14, and HApR14 + QAMP were added to Clearfil™ SE Bond. Microtensile bond strength (μTBS), cell viability (MTT method), and cell morphology (SEM) of these adhesives were studied. Characterization data confirmed that hydroxyapatites were successfully synthesized. Significant decrease μTBS was achieved for Clearfil™ SE Bond + HApP24 (p = 0.031) and Clearfil™ SE Bond + HApP36 (p = 0.008) when immediate (IM) and 12 months (12 M) were compared. No statistical difference (p > 0.05) was achieved when six months (6 M) and 12 M results of μTBS were compared for Clearfil™ SE Bond + HApR14. Clearfil™ SE Bond + QAMP, Clearfil™ SE Bond + HApR14 + QAMP, and Clearfil™ SE Bond presented no significant difference comparing storage periods. Lower cell viability was achieved when HApP24 and HApP36 were included to Clearfil™ SE Bond. Co-inclusion of QAMP + HApR14 into Clearfil™ SE Bond improved (p = 0.049) the viability of cells when compared to Clearfil™ SE Bond. SEM micrographs of fibroblast-like cells demonstrated consistent results with cell viability. This is the first report that hydrothermal nanorods of HAp and QAMP are co-included into adhesive system for providing remineralizing and antimicrobial properties at the same time as they kept bond stability.     

The role of surface-sealant application on bond effectiveness of all-in-one self-etch adhesives

Purpose: To examine microleakage around Class-V restorations bonded with 3 current all-in-one adhesive systems in the presence or absence of surface-sealant in different evaluation groups.

Materials and Methods: Clearfil S3 Bond, G-Aenial Bond, and Optibond All-in-One (AiO), were used in the Class-V cavities in accordance with the manufacturer’s instructions (control group) or were additionally combined with Fortify Plus surface-sealant (surface-sealant group). The two main treatment groups of the dentin adhesives were subdivided into four different evaluation groups (24 h, 6 months, 12 months, and 12 months with two applications); the teeth were immersed in 0.5% methylene blue dye solution for 24 h. Samples were then sectioned longitudinally in a bucco-lingual direction and evaluated for microleakage under a stereomicroscope. Dye penetration was scored at the enamel (occlusal) and dentin (gingival) margins.

Results: Microleakage scores were greater at the dentin margins compared with the enamel margins for Clearfil S3 Bond in all evaluation groups, whereas no difference was observed between enamel and dentin microleakage for Optibond AiO. Using Fortify Plus in the enamel margins decreased the microleakage scores of Clearfil S3 Bond. When the control and surface-sealant groups were compared in the G-Aenial Bond enamel margins, the application of surface-sealant significantly reduced microleakage after 6 and 12 months. For Optibond AiO, no statistically significant differences in enamel and dentin margins were observed between the control and surface-sealant application groups.

Conclusion: The application of surface-sealant could be considered appropriate for reducing microleakage in composite resin restorations, but this effect might depend on the dentin adhesive.     

Effect of different dentin adhesives and application modes on sealing ability of amalgam restorations

Purpose: The aim of the study was to evaluate the sealing ability of bonded amalgam restorations using different adhesive materials with different adhesive application methods including amalgam bonding application. Materials and methods: The prepared Class-V cavities were randomly assigned to four application groups of four tested dual-curing dentin adhesives (Scotchbond Multi-Purpose Plus, XP Bond, Xeno IV and Clearfil Liner Bond 2V), dual-curing resin-based cement (Panavia F2.0) and a control group (unlined amalgam). Group 1 adhesives were applied according to the instructions for direct light-curing, Group 2 chemical-curing mode was applied according to the manufacturer’s amalgam bonding instructions. Group 3 adhesives were first applied in light-curing mode, and then amalgam bonding adhesive was applied. Group 4 adhesives were first applied in chemical-curing mode, followed immediately by light-curing mode. After that, amalgam adhesive parts were applied; then, the amalgam was condensed and carved. After storage for 24 h in distilled water at 37 °C, restorations were finished and polished. The teeth were then thermocycled (500 cycles between 5 and 55 °C), and the specimens were examined for microleakage using methylene blue as a marker. Results: Compared to the control group, the adhesive application modes significantly reduced microleakage for both dentin and enamel margins (p < 0.05). In dentin margins of the adhesives tested, Group 4 showed the lowest leakage score. On the enamel margins for Scotchbond Multi-Purpose Plus and XP Bond, Group 1 showed the highest microleakage (p < 0.05). Conclusion: According to marginal sealing ability and ease of application, Group 2 was recommended for the etch and rinse systems, and Group 4 was also recommended for the self-etch systems under amalgam restorations.     

Biodegradation of caries-affected dentin bonding interface of fluoride and MDPB-containing adhesive system

The aim of this study was to evaluate the effect of a fluoride/MDPB (12-methacryloyloxydodecylpyridinium bromide)-containing adhesive system on the durability of a bond to permanent artificially induced caries-affected dentin (CAD) exposed to Streptococcus mutans culture and water storage. Twelve third molars were selected. Flat dentin surfaces were submitted to artificial caries development in S. mutans and Broth heart infusion (BHI). Caries-infected dentin was removed with burs according to clinical criteria and CAD cavities were restored with Adper Scotchbond Multi-Purpose (SBM) and Clearfil Protect Bond (CPB). Nontrimmed resin–dentin bonded interfaces (1 mm²) were stored in S. mutans+BHI for 3 days, in deionized water for 3 months, and afterwards subjected to microtensile bond strength test (μTBS). The control group was not submitted to storage and immediate μTBS testing was performed. Fractographic analysis was performed after μTBS testing. Four molars were restored as described, and morphological evaluation hybrid layer (HL) was performed by scanning electron microscopy (SEM). Two-way ANOVA with split-plot design and Tukey′s tests were performed. No difference was found between μTBS values of SBM and CPB irrespective of groups. Significant decrease was observed in μTBS values after S. mutans culture and water storage, but without difference between them. CPB had more homogenous hybrid layer than SBM. Fluoride/MDPB-containing adhesive system did not prevent degradation of CAD bond strength in both degradation methods.     

The Effect of Decalcified Root Surfaces on Dentinal Bond Strength

Microtensile bond strengths of current dentin adhesives to intact and decalcified root surfaces were evaluated. Two hundred and twenty-four extracted human incisors were divided into two groups as intact (IRD) and decalcified (DRD). The roots of DRD teeth were placed in a demineralization solution to produce artificial carious-like lesions. Root surfaces were slightly ground and treated with either Scotchbond Multi-Purpose (SMP), Adper Single Bond Plus (SBP), Adper Easy Bond (AEB), Scotchbond SE (SSE), Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Clearfil Tri-S Bond (CTS), FL-Bond II (FLB), XP Bond (XPB), iBond (IB), AdheSE Bond (ASE), Optibond Solo Plus (OSP), Prelude Dental Adhesive (PDA), and G-Bond (GB). Composite build-ups were formed on the bonded surfaces. After thermocycling, hour-glass shaped specimens with an area of 1 mm² at the bonded interface were subjected to microtensile testing. Resin–dentin interfaces were observed with SEM. Kruskal Wallis and Mann Whitney-U tests were used for statistical analysis. There was not significant difference between bond strengths to intact and decalcified dentin, with the exception of ASE and CSE, which had higher values to IRD (p < 0.05). SSE and CTS were the adhesives that showed higher bond strengths to DRD than to IRD, however the difference was not significant (p > 0.05). The self-etch adhesives performed better on both IRD and DRD surfaces than etch-and-rinse systems.     

Assessment of the initial and aged dentin bond strength of universal adhesives

This study evaluated the effect of mechanical loading on microtensile bond strengths (μTBS) of universal adhesives to dentin and quantified adhesive dentin penetration using micro-Raman spectroscopy. Human molars had occlusal dentin exposed and were allocated into eight groups: All-Bond Universal and Scotchbond Universal using etch-and-rinse and self-etch approaches, Adper Prompt L-Pop, Adper Single Bond Plus, Clearfil SE Bond, and Optibond FL. Following bonding procedures and build-ups, specimens were either stored in water at 37 °C for 24 h or mechanically loaded (50,000 cycles, 50 N) prior to μTBS test. Additional teeth were prepared for micro-Raman analysis of adhesive penetration and FE-SEM. Data were analyzed by two-way ANOVA and Tukey׳s post hoc test (P<0.05). Mechanical loading had no deleterious effect on μTBS with the exception of Adper Prompt L-Pop. Incomplete infiltration of the demineralized dentin was noticed for adhesives using the etch-and-rinse approach and for Scotchbond Universal in the self-etch approach.     

Influence of fluorescent dye on mechanical properties of adhesive systems

The aim of the study was to evaluate the influence of fluorescent dye (rhodamine B) on the ultimate tensile strength (UTS), elastic modulus (E), and flexural strength (FS) of different adhesives, specifically Scotchbond Multi-Purpose (3M ESPE, St. Paul, USA) and Clearfil SE Bond (Kuraray Medical Inc., Okayama, Japan). The bond of adhesive systems were mixed or not with 0.16 mg/mL of rhodamine B. The UTS values of beam-shaped specimens were measured with a universal testing machine (n=10). The FS and E values were evaluated with bar-shaped specimens (n=5). Data were statistically analyzed by two-way analysis of variance. No significant differences in UTS, E, or FS were found among the groups. Thus, at the concentration tested, incorporation of rhodamine B did not affect the mechanical properties of the adhesives.     

Effect of adhesive type and composite viscosity on the dentin bond strength

Objectives: Evaluate the influence of composite resins viscosity and type of cure of the adhesive systems on the bond strength of composite resins submitted to artificial aging.

Methods: Dentin specimens (n = 240) were divided into 2 groups: Group GC: GrandioSO, and Group GF: GrandioSO Heavy Flow. These groups were subdivided into 6: FM: Futurabond M – light cured, FDCC: Futurabond Dual Cure – chemical cured, FDCL: Futurabond Dual Cure – light cured, CS3: Clearfil S3 – light cured, CDCC: Clearfil Dual Cure – chemical cured, and CDCL: Clearfil Dual Cure – light cured. Resin blocks were build up on the dentin surface. Half of samples on each group were cut to obtain resin/dentin sticks (1 × 1 mm). The other half was first submitted to thermomechanical aging. The dentin/resin sticks were submitted to microtensile bond strength test and the results were analyzed using three-way ANOVA and Tukey’s test (α = 5%).

Results: ANOVA showed significant influence for adhesive (p = 0.0000) and aging (p = 0.0001). No significant influence of the composite viscosity on bond strength was observed (ANOVA: p = 0.0861). For adhesive, the results of Tukey’s test (MPa) were CDCC: 13.44 (±5.13)a; FM: 14,01 (±2.71)a; CDCL: 14.51 (±4.98)a; FDCC: 18.66 (±7.13)b; CS3: 18.80 (±6.50)b; FDCL: 19.18 (±7.39)b. For aging: AGED: 14.99 (±6.32)a; NOT AGED: 17.87 (±5.97)b.

Conclusion: Composite resin viscosities did not influence on the bond strength. Type of cure of the adhesives had influence on the bond strength. Thermomechanical aging decreased the bond strength.     

A novel chemical aging method for evaluating degradation of resin-dentin bond: a preliminary study

Purpose: to investigate the use of NaOH solution as storage medium on dentin micro-tensile bond strengths (MTBS) and the micromorphology of resin–dentin interfaces. Materials and Methods: mid-coronal dentin was exposed for 45 human third molars. One of five dentin adhesives investigated was applied to each dentin surface, followed by placement of a resin composite from the same manufacturer (Clearfil S3 Bond + Clearfil Majesty, Clearfil SE Bond + Clearfil Majesty, Kuraray Co. Ltd; Adper Easy One + Z250, Adper Single Bond 2 + Z250, 3M ESPE; Gluma Comfort Bond + Charisma, Heraeus Kulzer). Bonded specimens were sectioned through resin–dentin interfaces into multiple beams with a cross-sectional area of about 1 mm². The beams were kept in 10 wt% NaOH solution at 37 °C for 0, 2, 4, 6, 8, 10, or 12 h respectively prior to MTBS evaluation. The MTBS data were analyzed statistically. Failure modes were determined by stereomicroscopy. Representative fractured surfaces and resin–dentin interfaces were examined by scanning electron microscopy. Resin–dentin interfaces were also analyzed by transmission electron microscopy (TEM). Results: dentin MTBS decreased significantly with increased storage time in NaOH. Micro-gaps appeared along the resin–dentin interfaces after NaOH treatment and became wider over time. An electron-dense hybrid layer was observed by TEM in the control group, while an electron-lucent band was detected at the resin–dentin interfaces of specimens treated with NaOH for 8 h. Conclusion: aging of resin–dentin bonds in NaOH solution may be used as an expedited chemical aging method for evaluating degradation of dentin bond.     

NaOCl degradation of one-step one-bottle self-etch adhesives bonded to bovine dentine

Objective: The aim of the present study was to assess the influence of an in vitro aging regime (NaOCl storage) on dentine microtensile bond strength (μTBS) of five one-step one-bottle self-etch adhesives in comparison with bond strength of two-step self-etch adhesive.

Material and methods: Flattened dentine surfaces from 30 bovine incisors were bonded with five one-step one-bottle self-etch adhesives (iBond, Clearfil S3 Bond, AdheSE One F, G-Bond, Optibond all-in-one) and one two-step self-etching adhesive (Clearfil SE Bond). Composite buildups were done with microhybrid resin composite. Bonded samples were sectioned into resin–dentine sticks of 0.8 mm² cross section. Randomly selected 20 sticks were tested directly by microtensile bond strength testing machine, whereas another randomly selected 20 sticks were tested after being stored in solution of 10% NaOCl for 5 h. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests (p < 0.05).

Results: All adhesives exhibited similar dentine bond strength with exception of G-Bond. After NaOCl storage, μTBS reduced in all groups significantly. The lowest μTBS were found for G-Bond. Rest of one-step self-etch adhesives presented similar μTBS with two-step self-etch adhesive.

Conclusion: Interfaces of resin–dentine bonding are susceptible to NaOCl degradation. The amount of the destruction depends on adhesive system. NaOCl degradation of the nonresin encapsulated collagen fibers might decrease long-term stability of resin bonding with dentine.     

Bond Strength and Monomer Conversion of Bonding Agents Mixed with Restorative Composites Prior to Light Exposure

This study examined the effect of adhesive systems (either placed as directed or when mixed with composites prior to photocuring) on bond strength and monomer conversion. Occlusal surfaces of extracted human molars were ground flat and Scotchbond Multipurpose®, Single Bond®, or Clearfil SE Bond® adhesive systems were applied according to manufacturer's directions, mixed in situ with flowable or hybrid composites prior to photocuring. Specimens were prepared for microtensile bond-strength testing, and maximal bond strength at failure was recorded. Adhesives and composites were also placed on a diamond attenuated-total-reflectance unit, and infrared spectra were obtained kinetically. Addition of flowable Scotchbond prior to light-curing increased bond strength; however, no effect on Single Bond and Clearfil SE Bond was observed. The mixture of adhesives with composites resulted in lower monomer conversion for Scotchbond and Clearfil SE Bond.     

Fracture mechanics of dental adhesives supplemented with Polymethyl-vinyl-ether-co-maleic anhydride

The objective of this study was to determine the effect of Polymethyl-vinyl-ether-co-maleic anhydride (PVM/MA), called Gantrez AN, on interfacial fracture toughness (K_IC) of self-etch and etch-and-rinse dental adhesives. Sixty-five chevron-notched dentin-composite resin specimens were prepared. The following testing groups with different bonding agents were prepared and tested with a cross head speed of 0.1 mm/min: Clearfil SE (CF); Clearfil SE with Gantrez AN in primer (CFGp); Clearfil SE with Gantrez AN in bonding agent (CFG); Prime & Bond (PB); Prime & Bond with Gantrez AN (PBG). The K_IC values were determined and compared. The mode of failure was examined with light microscopy. The mean K_IC (standard deviation) of the Clearfil SE groups were 0.60 (0.09) MPa m^1/2 for CF, 0.64 (0.09) MPa m^1/2 for CFGp and 0.68 (0.16) MPa m^1/2 for CFG. The most common mode of fracture was cohesive. The mean K_IC (standard deviation) of the Prime & Bond groups were 0.63 (0.09) MPa m^1/2 for PB and 0.41 (0.11) MPa m^1/2 for PBG. Adhesive fracture most commonly occurred in the Prime & Bond groups. Gantrez AN did not adversely affect K_IC of the self-etch dental adhesive, but lowered K_IC of the etch-and-rinse adhesive. Addition of Gantrez AN to self-etch adhesive (CF) may be warranted to produce an antibacterial effect. Clinical studies of bacterial attachment and anti-bacterial effects to further justify the use of Gantrez AN in bonding agents are warranted.