Effect of sodium hypochlorite on bonding performance of universal adhesives to pulp chamber dentin.

Abstract Background/purpose: The most widely utilized irrigation solution in endodontic therapy is sodium hypochlorite (NaOCl). The purpose of this study was to assess the effects of NaOCl on the bond strength of four universal adhesives and one two-step self-etch adhesive to pulp chamber dentin. Materials and methods: One hundred sixteen extracted sound human third molars were used in this study. All the teeth were divided into two groups: (1) with NaOCl treatment and (2) without NaOCl treatment. These two groups were subdivided into five bonding groups: G-Premio Bond (GP), Beautibond Xtreme (BBX), Scotchbond Universal (SBU), Clearfil Universal Bond Quick (UBQ), and Clearfil Megabond 2 (MB2). The microtensile bond strength (µTBS), the fracture mode analysis, resin-dentin interface and dentin surface were observed by SEM. Two-way ANOVA was performed to analyze the µTBS (α = 0.05). Results: The µTBS of the NaOCl group significantly decreased for GP and MB2 (P < 0.05). Significant effects of adhesive (F = 12.182, P < 0.001), and irrigation (F = 27.224, P < 0.001) on the µTBS were observed, whereas interaction between adhesive and irrigation was not significant (F = 1.761, P = 0.144). The adhesive layer with variable thickness was observed in all groups with different morphological structures. Conclusion: The effect of NaOCl treatment on the µTBS differs depending on the type of adhesives.

The effect of an extra hydrophobic resin layer on the bond strength and durability of one-step universal adhesives used as a primer.

OBJECTIVES: To determine the effect of an extra hydrophobic resin layer (EHL) on the bond strength and durability of three different pH one-step universal adhesives (UAs) utilized in self-etch (SE) mode, and to explore whether UAs can be used as a primer in two-step bonding system. METHODS: Three different pH UAs were utilized: G-Premio Bond (GPB), Scotchbond Universal (SBU), All-Bond Universal (ABU), while the bonding agent of Clearfil SE Bond 2 (SE2) was selected as the EHL. For the EHL groups, EHL was applied after the air blow of each UA and before light curing. The microtensile bond strength (µTBS), fracture modes, interfacial structures and nanoleakage (NL) were evaluated after 24 h water storage and after 15,000 thermal cycling (TC). Elastic modulus (EM) and hardness (H) was tested by a nanoindenter after 24 h. RESULTS: Significantly higher µTBS was achieved in the GPB+EHL group compared with GPB both at 24 h and after 15,000 TC, while the additional use of EHL did not improve the µTBS of SBU and ABU significantly both at 24 h and after 15,000 TC. GPB+EHL demonstrated lower NL than GPB. The mean EM and H of the adhesive layer in GPB+EHL was significantly decreased compared with GPB. CONCLUSIONS: The results indicated that the bond strength and durability of low pH one-step UA (GPB) were significantly improved by additional application of EHL both at 24 h and after 15,000 TC, while no significant improvement was observed for ultra-mild one-step UAs (SBU and ABU). CLINICAL SIGNIFICANCE: This study indicates that GPB can be used as a primer in a two-step bonding system, while SBU and ABU may not be as effective. These findings may help guide clinicians in selecting the appropriate UAs and bonding techniques for different clinical scenarios.

Influence of Novel Experimental Light-Cured Resin Cement on Microtensile Bond Strength.

The purpose of this study was to evaluate the microtensile bond strength (µTBS) and Knoop hardness number (KHN) of a novel experimental light-cured resin cement (HL). Eighteen flat dentin surfaces of human molars were polished using #600 SiC paper and bonded to CAD/CAM resin blocks with the respective resin cements and composites: HL, Panavia V5 (PV), and Clearfil AP-X (AP). All specimens were stored in distilled water at 37 °C for 24 h and 7 days. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) observations were performed to evaluate filler morphology and to detect the elements. The resin cements had a significant effect on the immediate µTBS (F = 22.59, p < 0.05) and after water storage µTBS (F = 22.83, p < 0.05). Significant differences (p < 0.05) in the KHN between the tested materials were observed, and HL indicated the highest KHN when compared with PV. HL showed a combination of the regular-shaped filler and spherical-shaped filler within the matrix. Silicon was detected in HL from the EDX evaluation. HL exhibited better bonding performance and polymerization, which may have contributed to the improvement of the adhesive strength.

Cause-Effect Relationship of Varying Bonding Thicknesses in Dentin Adhesion of Universal Adhesives.

PURPOSE: To evaluate whether varying thicknesses of universal adhesives utilizing the additional coating strategy would affect their microtensile bond strength (µTBS) to dentin, hardness, and elastic modulus (mechanical properties). MATERIALS AND METHODS: Ninety-nine human maxillary premolars were cut to expose coronal dentin, ground with regular-grit diamond burs, and randomly distributed into 9 groups based on 1. adhesive: Scotchbond Universal Adhesive (SB; universal), G Premio Bond (GP; universal) and Clearfil Megabond 2 (MB; two-step self-etch; control); and 2. application strategy (one, two or three coats; each coat light cured). After adhesive application and resin composite buildup, the bonded teeth were stored in distilled water (37°C; 24 h). Resin-dentin sticks from eight premolars per group (each premolar yielded 3 sticks; n = 24 sticks altogether) were prepared for the µTBS test, followed by measurement of the adhesive thicknesses at their fractured ends using SEM. The mechanical properties of the adhesive layers produced by different coats were evaluated on separate resin-dentin slices (n = 3 teeth per group). RESULTS: Two coats significantly increased the µTBS (p < 0.001) of all the adhesives. The correlation between adhesive thickness and bond strength was positive for GP but negative for SB. MB did not show any correlation. Additional coating significantly increased the mechanical properties of GP (p < 0.05) but did not affect SB and MB (p < 0.05). CONCLUSION: An additional adhesive coating over the manufacturers' recommendations improved the bond strength of all the adhesives tested. However, the increased mechanical properties of the adhesives with additional curing was material dependent.

Interfacial Characterization of a Conventional Glass-Ionomer Cement after Functioning for 1-year In Vivo.

PURPOSE: To morphologically evaluate the interface between a conventional glass-ionomer cement (GIC) and dentin one day after placement, as well as the changes at the interface after one year of aging/functioning in monkey teeth. MATERIALS AND METHODS: On the buccal surfaces of seven intact teeth in each of two monkeys, shallow class V cavities were prepared, which were then filled with Fuji IX GP (GC) to provide 1-year in vivo data. A year later, two more teeth in each monkey were similarly prepared and restored for the 1-day in vivo group. The following day, the restored teeth were extracted and the restoration interfaces observed using transmission electron microscopy (TEM). In addition, restorations were similarly placed in two extracted human teeth (control, 1-day in vitro group) and observed a day after placement using TEM. RESULTS: The 1-day in vivo and in vitro results showed that the GIC appeared to bond to dentin through a demineralized zone similar to the hybrid layer produced by resinous adhesives. However, the interface between GIC and dentin after 1 year in vivo appeared to change over time: many needle-like crystals were detected within the remineralized layer and along the collagen fibrils. Slow diffusion of ions resulted in pores, which filled with mineral crystals and made the pores smaller. CONCLUSION: The interface between GIC and dentin morphologically changes over time, and recrystallization or remineralization at the interface may occur (1 year in vivo).

Antibacterial potential of colloidal platinum nanoparticles against Streptococcus mutans.

This study evaluated the antibacterial activity of colloidal platinum nanoparticles (CPNs) toward Streptococcus mutans (S. mutans) viability. S. mutans 109c was treated with water and three CPN solutions at 37°C for 24 h (i.e., control, PAA-Pt, C-Pt, C-CyD-Pt). Dilution series (10-1-10-5) were prepared using brain heart infusion (BHI) broth for all samples, and a 100 µL suspension of each dilution was spread onto a BHI agar plate. Colony-forming units (CFU/mL) were determined after 24 h. The effects of CPNs on S. mutans survival and biofilm formation were investigated using fluorescence and scanning electron microscopies. The antibacterial rate of S. mutans increased with increasing concentrations of all three CPNs, with PAA-Pt nanoparticles exhibiting the highest antibacterial efficacy. CPNs were found to reduce S. mutans growth and inhibit biofilm formation remarkably.

Pulpal response to mineral trioxide aggregate containing phosphorylated pullulan-based capping material.

This study aimed to evaluate the pulpal responses of monkey's pulp after direct pulp capping (DPC) with the novel mineral trioxide aggregate containing phosphorylated pullulan-based material (MTAPPL). Seventy-two teeth were randomly divided into four groups: MTAPPL; Nex-Cem MTA (NX); TheraCal LC (TH); and Dycal (DY). Histopathological changes in the pulps were observed at days 3, 7 and 70. On day 3, mild inflammatory responses were observed in the MTAPPL, no to moderate inflammatory responses in the TH, whereas moderate inflammatory responses in the NX and DY. No mineralized tissue formation (MTF) was observed in all groups. On day 7, no or mild inflammatory responses were observed in all groups. Initial MTF was observed except for DY. No inflammation with complete MTF including presence of odontoblast-like cells was observed in the MTAPPL, NX and TH groups at day 70. These findings indicate that MTAPPL could be an efficient DPC material.

Effect of conditioning and 1 year aging on the bond strength and interfacial morphology of glass-ionomer cement bonded to dentin.

OBJECTIVE: The purpose of this study was to determine the bond stability and the change in interfacial ultra-structure of a conventional glass-ionomer cement bonded to dentin, with and without pre-treatment using a polyalkenoic acid conditioner. METHODS: The occlusal dentin surfaces of six teeth were ground flat. Glass-ionomer cement was bonded to the surfaces either with or without polyalkenoic acid conditioning. The teeth were sectioned into 1-mm2 stick-shaped specimens. The specimens obtained were randomly assigned to two groups with different periods of storage in water: 1 week and 1 year. The micro-tensile bond strength (µTBS) was determined for each storage time. Additional specimens were prepared for Transmission Electron Microscopy (TEM); they were produced with or without prior polyalkenoic acid conditioning in the same way as in the µTBS test. RESULTS: There was no significant difference in µTBS to conditioned dentin and non-conditioned dentin (p > 0.05). The failures appeared to be of a mixed nature, although aging caused more areas of cohesive than adhesive failure in both groups. The TEM observation showed an intermediate layer, a matrix-rich layer and a partially demineralized layer in the polyalkenoic acid conditioned group. SIGNIFICANCE: Aging did not reduce the bond strength of the conventional glass-ionomer cement to dentin with or without the use of a polyalkenoic acid conditioner.

Bonding Performance of a Hydrophilic Amide Monomer Containing Adhesive to Occlusal and Cervical Dentin.

This study aimed to evaluate the bonding performance of a new one-step self-etching adhesive system containing a novel hydrophilic amide monomer. Clearfil Universal Bond Quick (CUB) and Clearfil Megabond 2 (CMB) were used as the one-step and two-step adhesive systems, respectively. Flat dentin surfaces of human premolars were exposed using #600 SiC (silicon carbide) and bonded with the respective adhesives of each system. The teeth were sectioned to obtain beams (1 mm × 1 mm) after 24 h of water storage. The mean bond strength and standard deviations (MPa) on an occlusal surface were as follows: CUB: 45.9 ± 19.7 and CMB: 67.9 ± 25.3. The values for cervical ones were CUB: 56.0 ± 20.3 and CMB: 67.6 ± 16.0, respectively. In both conditions, the microtensile bond strength (µTBS) value was lower than that of CMB. As seen during the microscopic observation, no adhesive failure was observed after µTBS testing because CUB formed a firm and tight adhesive interface.

The microtensile bond strength test: Its historical background and application to bond testing.

Microtensile bond strength (µTBS) test was introduced in 1994. Since then, it has been utilized profoundly across many bond strength testing laboratories, making it currently one of the most standard and versatile bond strength test. Although it is a static and strength-based method, together with the morphological and spectroscopic investigations, it has been contributing immensely in the advancement of dentin adhesive systems. µTBS test has a greater discriminative capability than the traditional macro-shear bond test. During the early stage of its development, the authors predicted that this testing method would enable evaluation of the adhesive performances of resins to excavated carious or sclerotic dentin and the regional bond strengths of various portions of the cavity. In addition, they also stated the possibility of comparing the long-term stability of resin adhesion at various portions of the cavity walls on teeth extracted at various times after insertion of bonded restorations. In this review, we discussed the historical background, inception and the application of the µTBS test and proposed directions for further improvement of this testing method.

Bioactive Two-step Approach: Promising Bonding Strategy for a One-step Self-etch Universal Adhesive.

PURPOSE: To evaluate the potential of an additional application of two novel hydrophobic experimental adhesive resins with or without bioactive zinc fluoride glass to promote the bond strength of a one-step self-etch universal adhesive. MATERIALS AND METHODS: Three self-etch universal adhesives, G-Premio Bond (GPB), Scotchbond Universal (SBU) and Clearfil SE Bond 2 (SE2), and two experimental adhesive resins, BZF210 and BZF21, were used in this study; thus, five groups were formed: GPB, GPB+BZF210, GPB+BZF21, SBU, and SE2. The adhesives were applied to flat dentin surfaces according to each manufacturer's instructions. The microtensile bond strengths (µTBS) were evaluated after 24-h water storage. The fracture modes and interfacial structures were analyzed using SEM, while elemental analysis was performed using SEM-EDS. The data were analyzed using one-way ANOVA and the Games-Howell test (p < 0.05). RESULTS: Significantly higher µTBS was achieved by additional application of BZF210 (48.68 ± 6.59 MPa) and BZF21 (58.58 ± 2.84 MPa) compared with GPB (33.57 ± 4.22 MPa) alone. Most failures occurred above the smear layer in GBP, while more cohesive and mixed failures were observed in GBP+BZF210, GPB+BZF21, SBU, and SE2. The interfacial structures revealed that GBP+BZF210 and GPB+BZF21 had more and longer resin tags than did GPB. SEM-EDS showed a particularly high peak of zinc in GPB+BZF21. CONCLUSIONS: The bond strength of GPB was significantly improved by the additional application of BZF210 and BZF21. Using an additional bioactive hydrophobic layer on a one-step, self-etch universal adhesive can significantly improve its bonding efficacy and extend its clinical options.

GPDM- and 10-MDP-based Self-etch Adhesives Bonded to Bur-cut and Uncut Enamel - "Immediate" and "Aged" µTBS.

PURPOSE: To determine the microtensile bond strength (µTBS) of two 2-step self-etch adhesives (SEAs) to bur-cut and uncut enamel. MATERIALS AND METHODS: The buccal and lingual enamel surfaces of 15 teeth were ground flat ("bur-cut" enamel), while the enamel surface of another set of 15 teeth was solely prophylactically cleaned ("uncut" enamel). Resin composite was bonded to the surfaces using the GPDM-based SEA OptiBond XTR (Kerr), the 10-MDP-based SEA Clearfil SE Bond (Kuraray Noritake), or the 3-step etch-and-rinse adhesive (E&RA) OptiBond FL (Kerr) that served as the gold-standard control. After 1-week water storage at 37°C, specimens were serially cut into 1-mm2 stick-shaped microspecimens, of which half per tooth were further subjected to 20,000 thermocycles (TC) prior to µTBS testing. Data were statistically analyzed using ANOVA and the post-hoc Tukey test. The interfacial ultrastructure of the GPDM-based SEA OptiBond XTR with uncut and bur-cut enamel was additionally characterized with transmission electron microscopy (TEM). RESULTS: After 1-week water storage and upon TC aging, both SEAs bonded significantly (p < 0.05) less effectively to both bur-cut and uncut enamel than did the control OptiBond FL, except when OptiBond XTR was bonded to bur-cut enamel; then a similarly high µTBS was recorded (p > 0.05). TEM interfacial characterization revealed a tight interaction of Optibond XTR with both bur-cut and uncut enamel. CONCLUSION: The best bonding efficacy to enamel is still achieved by etching with phosphoric acid, following an E&R approach, while the higher etching efficacy of the GPDM-based SEA may result in equally effective bonding, provided that the enamel is bur-roughened first.

Bond performance of "Touch and Cure" adhesives on resin core systems.

The purpose of this study was to compare the micro-tensile bond strength (µTBS) of three resin core composites to dentin and to examine the bonded interface of the composites. One experimental TDK-03(TD) and, two commercial, DC core Automix One (DC) and Unifil core EM(UN) were used. Flat dentin surfaces of human molars were exposed using #600 SiC paper and bonded with the respective adhesive of each system. After bonding, the composites were built up on the surfaces and cured under two conditions: "light condition" or "dark condition". µTBSs (MPa) in the light condition were: TD; 60.02±17.08, DC; 38.21±13.70, and UN; 29.50±9.71; in the dark condition: TD; 54.62±17.11, DC; 8.40±4.81, and UN; 9.47±6.56. Dark curing negatively affected the bond strength of the two commercial resin-core materials. The experimental material was not affected by the curing conditions.

Evaluation of microtensile bond strength of self-etching adhesives on normal and caries-affected dentin.

The purpose of this study was to evaluate the µTBS (microtensile bond strength) of currently available self-etching adhesives with an experimental self-etch adhesive in normal and caries-affected dentin, using a portable hardness measuring device, in order to standardize dentin Knoop hardness. Normal (ND) and caries-affected dentin (CAD) were obtained from twenty human molars with class II natural caries. The following adhesive systems were tested: Mega Bond (MB), a 2-step self-etching adhesive; MTB-200 (MTB), an experimental 1-step self-etching adhesive (1-SEA), and two commercially available one-step self-etching systems, G-Bond Plus (GB) and Adper Easy Bond (EB). MB-ND achieved the highest µTBS (p<0.05). The mean µTBS was statistically lower in CAD than in ND for all adhesives tested (p<0.05), and the 2-step self-etch adhesive achieved better overall performance than the 1-step self-etch adhesives.

Effect of Conditioning and Aging on the Bond Strength and Interfacial Morphology of Glass-ionomer Cement Bonded to Dentin.

PURPOSE: To determine the bond stability and the change in interfacial ultrastructure of a conventional glassionomer cement bonded to dentin, with and without pretreatment using a polyalkenoic acid conditioner. MATERIALS AND METHODS: The occlusal dentin surfaces of 10 teeth were ground flat. Glass-ionomer cement was bonded to the surfaces either with or without polyalkenoic acid conditioning. The teeth were sectioned into 1-mm2 stick-shaped specimens. The 200 specimens obtained were randomly assigned to four groups with different periods of storage in water: 1 week, 1 month, 3 months, and 6 months. The microtensile bond strength (µTBS) was determined for each storage time. Additional specimens were prepared for transmission electron microscopy (TEM); they were produced with or without prior polyalkenoic acid conditioning in the same manner as for the µTBS test. RESULTS: There was no significant difference in µTBS to conditioned dentin (p > 0.05). After 6 months of aging, the µTBS to non-conditioned dentin was significantly reduced as compared to the 1-week, 1-month, and 3-month results (p < 0.05). The failures appeared to be of a mixed nature, although aging caused more areas of cohesive than adhesive failure in all groups. TEM observation showed a demineralized layer and an amorphous gel phase in the polyalkenoic acid conditioned group. CONCLUSION: Aging did not reduce the bond strength of the conventional glass-ionomer cement to dentin when the surface was pretreated with a polyalkenoic acid conditioner.

Effect of remaining dentin thickness on microtensile bond strength of current adhesive systems.

The purpose of this study was to evaluate the effect of remaining dentin thickness (RDT) on the bond strength of current adhesive systems. Third molars were randomly allocated among four groups depending on the adhesive system used: Clearfil SE Bond ONE (SE1), G-Bond PLUS (GB), BeautiBond (BB), and Clearfil Mega Bond (MB). Bonded specimens were stored in water at 37°C for 24 h. Teeth were then sectioned perpendicular to the adhesive interface to produce beams. After measuring RDT of each beam, microtensile bond strength test was carried out using a universal testing machine at a crosshead speed of 1 mm/min. All data were analyzed by linear regression analysis. Bond strengths of one-step self-etch materials used in this study increased with an increase in RDT. In contrast, that of two-step self-etch adhesive system was not affected by RDT.

Microtensile bond strength of a newly developed resin cement to dentin.

The purpose of this study was to evaluate the microtensile bond strength (µTBS) of a newly developed resin cement, ECD-89 (ECD, Tokuyama Dental, Tokyo, Japan) to dentin and to observe the interfacial micromorphology by comparing with two commercial resin cements, Multilink Automix (MA, Ivoclar Vivadent AG, Schaan, Liechtenstein) and Panavia F2.0 (PF, Kuraray Noritake Dental, Tokyo, Japan). Flat dentin surfaces of human third molars were exposed using #600 SiC. After application of primer and cement to the dentin surface, each cement was applied and cured with light (light condition) or without light (dark condition). The teeth were sectioned to obtain beams (1 mm×1 mm) after 24 h of water storage. The mean bond strengths and SDs (MPa) were: ECD: 68.6±14.9, MA: 39.2±18.9, PF: 39.4±18.5 and ECD: 54.5±22.4, MA: 36.7±15.6, PF: 13.4±4.46 when cured in light and dark condition, respectively. In both conditions, ECD-89 showed statistically higher µTBS than the others.

Bonding performance of a newly developed step-less all-in-one system on dentin.

The purpose of this study was to evaluate the short-term µTBS (Micro-tensile bond strength) and microscopic (SEM and TEM) observation of four recent adhesives. One adhesive was an experimental step-less 1-step system (LLB-2, Tokuyama Dental), which is an all-in-one system without the light-curing step in the application process. The other two were self-adhering light-cured flowable composite resin systems FLD (Fusio Liquid Dentin, Pentron Clinical Technologies) and VF (Vertise Flow Dental Restorative Materials, Kerr Corporation), which combine all the bonding steps together. A 2-step self-etching system MG (Clearfil MegaBond, Kuarary Medical) was employed as the control group in this study. The µTBS of MG was the highest (79.0 MPa) followed by that of LLB-2 (63.1 MPa), FLD (23.6 MPa), and VF (13.1 MPa). The microscopic observations showed that MG and LLB-2 had an approximately 20 µm and 5 µm adhesive layer respectively, without bubble or gap-formation at the resin-dentin interface, which were found in FLD and VF.

Expansion of nanotechnology for dentistry: effect of colloidal platinum nanoparticles on dentin adhesion mediated by 4-META/MMA-TBB.

PURPOSE: To investigate the effect of Colloidal Platinum Nanoparticles (CPN) on the bond strength between dentin and 4-META/MMA-TBB resin using different concentrations of CPN. MATERIALS AND METHODS: Twenty-five extracted human third molars were stored in 0.5% chloramine T. The occlusal dentin slices were prepared by grinding occlusal surfaces of each tooth and polishing with 600-grit silicon carbide paper under running water. One control and four experimental groups (2 specimens per group) were used as follows: a) dentin surfaces treated with 10-3 solution, followed by rinsing with water and subsequently an acrylic rod bonded with hand-mixed 4META/MMA-TBB resin (Super-Bond C&B, Sun Medical) (control); b) dentin surfaces treated with 10-3 etching solution, followed by rinsing with water and application of CPN (100% or 10%) as a primer solution for 60 s and rinsed with water for 20 s, then an acrylic rod bonded with Super-Bond C&B(Etch-CPN [100% or 10%]); c) dentin surfaces treated with CPN (100% or 10%) for 60 s, rinsed with water for 20 s, followed by application of 10-3 solution, then an acrylic rod bonded with Super-Bond C&B (CPN-Etch [100% or 10%]). After storage in 37°C water, specimens were sectioned into beams (cross-sectional area: 1 mm2) for microtensile bond strength testing at a crosshead speed of 1mm/min. The data were analyzed using the Games-Howell method (p < 0.05; n = 15). RESULTS: Etch-CPN (100), CPN-Etch(100) and CPN-Etch (10) showed significantly higher bond strengths compared to the control. When using 10% CPN, the highest bond strength was demonstrated. The bond strength of 4META/MMA-TBB resin was approximately doubled by CPN application. CONCLUSION: The results of this study showed that higher bond strengths are obtained when treating dentin with a lower concentration of CPN. Further evaluation to optimize conditions such as the application time and rinsing time are required.

Effect of application time of colloidal platinum nanoparticles on the microtensile bond strength to dentin.

The purpose of this study was to investigate the effect of application time of colloidal platinum nanoparticles (CPN) on bond strength. Dentin surfaces were subjected to one of the following treatments: (A) Etching with 10% citric acid-3% FeCl(3 )solution (10-3 solution); (B) Etching with 10-3 solution followed by applying CPN as a primer solution for 10, 20, 30, or 60 seconds; and (C) Priming with CPN for 10, 20, 30, or 60 seconds followed by etching with 10-3 solution. An acrylic rod was bonded to each treated dentin surface using 4-META/MMA-TBB resin. Bonded specimens were sectioned into beams for microtensile bond strength testing. In groups (B) and (C), highest bond strength was obtained when dentin surfaces were treated with CPN for 30 seconds. This meant that the CPN primer solution either enhanced the penetration of resin into dentin or the degree of conversion of 4-META/MMA-TBB resin. Within the limitations of this study, treatment with 0.1 mN CPN primer solution followed by 20 seconds of water rinsing resulted in high bond strength.