Bond strength and interfacial morphology of adhesives to primary teeth dentin

PURPOSES: To evaluate (1) the shear bond strength to the dentin of primary teeth and failure site of hydrophilic dentin bonding agents, (2) the interfacial micromorphology of these adhesives on primary teeth. MATERIALS AND METHODS: Seventy-six primary noncarious molars stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on superficial dentin to which the adhesives and resin composite could be applied. After preparing the dentin surface, the teeth were stored in distilled water for 48 hours. They were then rinsed and dried with compressed air and divided at random into four groups of 16 specimens each: Group 1: Dentastic; Group 2: One-Step; Group 3: Prime & Bond 2.0; Group 4: Compoglass SCA. Z100 resin was used in all groups. All specimens were thermocycled (500x) and sheared in an Instron machine. After shear testing, the debonding sites of all samples were examined with a stereomicroscope and selected samples were also examined with the scanning electron microscope. Three additional samples per group were used to evaluate the resin adaptation to dentin. RESULTS: The results in MPa were: Dentastic 19.62 (4.67); One-Step 11.24 (3.67), Prime & Bond 22.38 (6.47), Compoglass SCA 18.88 (4.04). ANOVA (P < 0.0001) revealed that there was a significant difference between the groups. The Student-Newman-Keuls test (P < 0.05) showed no statistically significant difference between Dentastic, Prime & Bond and Compoglass SCA. However, these three groups were statistically significantly higher than One Step. In the Dentastic group, 14 of 16 samples revealed resin cohesive failure (resin fracture) while two of 16 displayed dentin cohesive failure (dentin fracture). In the One Step group, 15 samples failed at the resin and one sample showed dentin cohesive failure. In the Prime & Bond group, 12 specimens revealed resin cohesive failure while four displayed dentin cohesive failure. In the Compoglass SCA group, 13 samples had resin cohesive failures while three had dentin cohesive failures. All samples revealed an intimate adaptation to the dentin displaying resin tag formation.     

Effects of moxonidine and clonidine on renal function and blood pressure in anesthetized rats

OBJECTIVES: This study was conducted 1) to characterize through SEM analysis the resin-dentin interface produced by single-bottle primer/adhesives and a three-component system [Scotchbond Multi-Purpose (3M Dental)] and 2) to evaluate the shear bond strength to dentin of these adhesive systems. METHODS: Single-bottle primer/adhesives [Bond 1 (Jeneric/Pentron), Single Bond, (3M Dental Products); One Step (Bisco Inc.), OptiBond Solo (Kerr Corp.), Prime & Bond 2.1 (L.D. Caulk-Dentsply), Syntac Single-Component (Ivoclar-Vivadent), Tenure Quilk with Fluoride (Den-Mat)] were used according to manufacturers' instructions to bond resin composite to flat dentinal surfaces of extracted human third molars (n = 15). All samples were thermocycled 300x. Twelve specimens per group were used to measure shear bond strength and three specimens were used to evaluate the interfacial morphology under SEM. A one-way ANOVA and Turkey's test were used to assess the results. RESULTS: Mean shear bond strengths in MPa +/- SD for the groups ranged from 22.27 +/- 4.5 MPa for Single Bond to 7.6 +/- 3.9 MPa for Syntac Single-Component. The statistical analysis indicated that Single Bond produced significantly higher (p < 0.001) bond strengths than Syntac Single-Component, Prime & Bond 2.1, Bond 1 and Tenure Quik With Fluoride. Bond strengths for Syntac Single-Component were significantly lower than One-Step, OptiBond Solo, Scotchbond Multi-Purpose Plus and Single Bond. SEM examination clearly revealed the formation of a distinct hybrid layer for all adhesive systems; however, minor variations in ultrastructure existed among products. SIGNIFICANCE: Some single-bottle primer/adhesive present in vitro bond strengths and hybrid layer formation similar to those found for the conventional three-component adhesive system tested.     

The effect of dentin primer on the tensile bond strength to human enamel

Four third-generation dentin bonding products (Scotchbond Multi-Purpose, Optibond, All-Bond 2, and Prisma Universal Bond 3) were tested to evaluate their tensile bond strength to enamel. Test enamel specimens were etched, primed, and polymerized according to each manufacturer's directions. Control specimens were treated identically except the primer application was eliminated. The results demonstrated that the dentin primer significantly increased the tensile bond strength of All-Bond 2, significantly decreased the tensile bond strength of Scotchbond Multi-Purpose and Optibond, and had no significant effect for Prisma Universal Bond 3. A one-way analysis of variance was run between the eight groups tested, and three significant subsets were found (P < .05). The subset with the highest mean tensile bond strengths consisted of Prisma Universal Bond 3 primed and nonprimed, All-Bond 2 primed, and Optibond nonprimed.     

Adhesion of a compomer to dental structures

The objective of this study was to evaluate the bond strength of a compomer to dental enamel, dentin, and cementum. Flat surfaces of these tissues were obtained from recently extracted human teeth. The different substrates were either treated with PSA (a primer and adhesive) or acid etched (35% phosphoric acid gel) and treated with PSA. Cylindrical specimens of compomer were then bonded to the substrates. Shear bond strength was determined after a 24-hour immersion in 37 degrees C water. Significant differences were found between both treatments on enamel, while none were found on dentin or cementum. The use of acid etchant on enamel as a surface-conditioning step previous to priming with PSA allowed a better bond between Dyract compomer and that substrate; acid etching was not particularly needed on dentin and cementum.     

Marginal adaptation of resin-bonded light-cured glass ionomers in dentin cavities

PURPOSE: To investigate the marginal adaptation of resin-modified glass ionomer cements in dentin cavities placed with or without additional application of resin bonding systems. MATERIALS AND METHODS: Three resin-modified materials (Fuji II LC, Photac-Fil, Vitremer), one compomer (Dyract) and as reference an adhesively bonded resin composite system (Gluma CPS-Pekafill) were used. Flat peripheral dentin surfaces on human molar teeth were produced by wet grinding on SiC paper. Cylindrical cavities, 3.5 mm wide, were prepared in these dentin areas and restored with the individual materials. Sixty cavities were pretreated and restored as requested by the respective manufacturers. Following water storage of the specimens for 15 minutes or 24 hours, excess was gently removed by wet grinding for microscopic inspection of the marginal area. Additionally, in 30 cavities an experimental one-component adhesive resin system, a proprietary dimethacrylate and HEMA mixture dissolved in acetone, was combined with each of the restoratives for evaluation after 15-minutes water storage. Finally, in six cavities each, Dyract was combined with Prime and Bond 2.0, and Vitremer with Scotchbond Multi-Purpose Plus for assessment after 15 minutes. Maximum marginal gap widths (MGW) were measured. One-way ANOVA by ranks (Kruskal-Wallis-Test) followed by Wilcoxon's Two-Sample test were used to study the statistical difference of MGW among the treatment groups at a rejection level P = 0.05. RESULTS: Neither the conventionally placed material systems nor the restorations in combination with adhesives showed consistently gap-free margins after 15-minute water storage. After 24-hour storage with Vitremer 4 of the 6 restorations were gap-free, whereas with all other materials only perfect margins were registered. There was, however, no significant difference between the groups. Application of the experimental and/or the specific resin bonding agents had no effect on early MGW except for the Photac-Fil group, which was significantly reduced.     

Initial tensile bond strength of resin-modified glass ionomers and polyacid-modified resins on perfused primary dentin

The objective of this study was to evaluate the initial tensile bond strength of a resin-modified glass ionomer (Photac-Fil) and two polyacid-modified composite resins (Compoglass, Dyract) to primary dentin. A hybrid composite resin (Tetric) and two chemical cured glass ionomers (BaseLine, Hi-Dense) served as controls. Ninety caries-free dentinal discs were ground flat and perfused with Ringer's solution. Dentinal surfaces were conditioned (except for Base Line). From each material, fifteen standardized specimens were attached to the dentin. Light-curing of the respective materials followed (1 min), and adhesion was tested with a universal testing machine 15 min after application. The highest initial bond strength was observed with Tetric (5.17 MPa). Closed test procedure (Kruskal-Wallis) showed significant differences between all materials (P < 0.05), except for Compoglass (1.82 MPa) vs. Dyract (2.35 MPa), and BaseLine (0.37 MPa) vs. Photac-Fil (0.42 MPa). The condensable glass ionomer Hi-Dense revealed a mean tensile bond strength of 0.79 MPa. Adhesion of (polyacid-modified) composite resins is superior to the other tested glass ionomer materials, when applied to perfused primary dentin.     

Effect of application technique and dentin bonding agent interaction on shear bond strength

This study evaluated the interaction of five clinical application techniques and the shear bond strength of four DBAs (OptiBond FL, Clearfil SE Bond, PQ1 and Prime & Bond NT). A hybrid resin composite (Herculite XRV restorative resin) was attached to human dentin surfaces using five application techniques: Group A--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group B--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for three seconds to remove the excess adhesive. Group C--adhesive spread with 3M brush for 30 seconds, excess adhesive removed with a clean brush, two strokes side by side, no compressed air. Group D--adhesive spread with a Micro-applicator brush for 30 seconds followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group E--adhesive spread with a Micro-applicator brush for 30 seconds, the excess adhesive removed with a clean brush, two strokes side by side and no compressed air. The specimens were stored in distilled water at 37 degrees C for 24 hours, followed by thermocycling between 5 degrees C and 55 degrees C for 1,000 cycles. The shear bond strengths were determined on a universal testing machine operating with a crosshead speed of 5 mm/minute. The fracture sites were examined by 20x stereo microscope to determine the type of failure that occurred during the debonding procedure. Bond strength data were compared with analysis of variance at a significance level of p<0.05. Post hoc comparisons of means were performed with t-tests with p-values adjusted for multiple comparisons. This in vitro study concluded that there was an interaction between the application technique and bonding agent tested. All DBAs utilized the one-second compressed air technique, which yielded the highest bond strengths.     

Wet bonding: effect of drying time and distance

PURPOSE: To examine the effect of various drying times and air syringe-to-tooth distances on the shear bond strength of a dentin adhesive that requires a wet surface for maximum effectiveness. MATERIALS AND METHODS: Seventy extracted human molars were acid etched. The surface of the etched dentin was rinsed and dried with compressed air for 1, 3, or 5 seconds from a distance from either a distance of 1 or 10 cm. The adhesive One-Step was then applied, composite cylinders were attached and shear bond strengths were obtained. RESULTS: Drying time and distance had a significant impact on the resultant shear bond strengths. Longer drying times and shorter syringe-to-tooth distances negatively affected the bond strength of the adhesive studied.     

Effects of etchants, surface moisture, and resin composite on dentin bond strengths

This in vitro study evaluated the effects of etchant type, surface moisture, and resin composite type on the shear bond strength of dentin adhesives. Three adhesives which bond to etched dentin were used in the study: All-Bond 2, Amalgambond, and Clearfil Photo Bond. Occlusal enamel was removed from 200 human molars to expose dentin. The dentin surfaces were etched, treated with a dentin adhesive system, and bonded with resin composite. After thermocycling and storage, the composite columns were fractured from dentin using an Instron machine. Bond strengths were calculated and subjected to a statistical analysis. Etchant type, surface moisture, and resin composite type all had significant effects on dentin bond strengths. Overall, the highest bond strengths were obtained with 10/3 etchant, moist dentin, and hybrid composite. The highest bond strengths for All-Bond 2 and Amalgambond were obtained by using the manufacturer's recommended etchant, moist dentin, and a hybrid composite. The mean bond strengths for All-Bond and Amalgambond under these conditions were 22.5 and 19.0 MPa, respectively. Clearfil Photo Bond had significantly lower bond strengths, but was relatively unaffected by changes in experimental conditions.     

Effects of argon laser curing on dentin shear bond strengths

Previous studies have demonstrated the ability of the argon laser to polymerize light-activated materials and improve enamel shear bond strengths. This study was conducted to evaluate the effects of the argon laser on dentin shear bond strengths of current dentin bonding systems. Argon laser (HGM Model 8) at 231 and 280 mW, 5 sec bonding agent, 10 sec composite, and a conventional curing light (Translux EC/Kulzer) at 10 sec bonding agent, 20 sec composite were used to polymerize samples of dentin bonding systems [Scotchbond Multi-Purpose Plus (3M) and Prime Bond (Dentsply/Caulk), both with TPH (Dentsply/Caulk) composite]. A flat dentin bonding site (600 grit) was prepared on the buccal surface of extracted human teeth. Twelve samples were made for each set of parameters for both laser and conventional light totaling 48 samples. Samples were stored in distilled water in light-proof containers for 24 h at 37 degrees C. Shear bond strengths (MPa) were determined for each sample on the Instron testing machine. Mean values were calculated for each set of data and ANOVA with Fisher PLSD were used for statistical analysis. The argon laser provided bond strengths that were 21-24% greater than those of the conventional curing light system.     

Resin-modified glass ionomers for luting posterior ceramic restorations

OBJECTIVES: Until recently, esthetic inlay restorations in posterior teeth have been limited to cavities surrounded by enamel. Dentin adhesive systems in combination with luting composites and light-cured resin-modified glass ionomer cements offer a possibility for bonding ceramic inlays to cavities when the cervical margin is in dentin. This study was designed to compare in vitro marginal integrity of ceramic inlays bonded to dentin to restorations placed in cavities with margins located entirely in the enamel. METHODS: In the present in vitro study, the sealing abilities of a dentin bonding agent/luting composite combination (Syntac/Dual Cement, Vivadent) and resin-modified glass ionomers (Photac Fil, Photac Bond, ESPE; Dyract, De Trey Dentsply; Fuji II LC, GC Dental Industrial Corp.; and Vitremer, 3M Dental Products) used as luting agents in cavities extending beyond the cemento-enamel junction, were compared to the sealing abilities of a conventional luting composite (Vita Cerec Duo Cement, Vita) in cavities within sound enamel. SEM analysis and dye penetration were performed to evaluate marginal integrity at the cervical cavity margins. RESULTS: The dentin bonding agent/luting composite combination (Syntac/Dual Cement) rendered a marginal seal within the dentin similar to the quality obtained with the conventional luting procedures within sound enamel. When three out of the five resin-modified glass ionomers were used as luting agents (Dyract, Fuji II LC and Vitremer), the results were comparable to those reported for the dentin bonding agents and the conventional method. SIGNIFICANCE: Light-cured resin-modified glass ionomer cements may be considered as an alternative to dentin bonding agents when the cavity margins of ceramic inlay restorations are within the dentin. However, further studies, e.g., wear resistance, must be performed.     

Bond strengths and SEM evaluation of Clearfil Liner Bond 2

PURPOSE: To evaluate a dental adhesive system that uses a single conditioning/primer agent. MATERIALS AND METHODS: Twenty-five flat enamel and dentin bonding sites were prepared to 600 grit on human molar teeth. The Clearfil Liner Bond 2 adhesive system was used to bond Clearfil AP-X composite to both enamel and dentin. After 24 hours of water storage, shear bond strengths were determined using an Instron testing machine. Fifty V-shaped cavity preparations were prepared in human molar teeth with an enamel and cementum margin. Composite restorations were placed using the new adhesive system. The teeth were stored for 24 hours, thermocycled, stained with AgNO3 , sectioned and examined for microleakage. SEM examinations were also completed to evaluate the effects of the treatment steps on enamel and dentin surfaces. RESULTS: Mean shear bond strengths for the experimental adhesive to enamel and dentin were 28.2 +/- 4.9 and 19.4 +/- 3.1 MPa. A t-test revealed that the enamel bond strength was significantly greater (P<0.05) than the dentin strength. No marginal leakage was observed from the enamel margins of the restorations. Three restorations showed minimal leakage from the cementum margins. SEM examinations showed resin penetration into both the conditioned enamel and dentin surfaces. The adhesive system produced high bond strengths to both enamel and dentin, exhibited very minimal microleakage and was easy to use.     

Strength of secondary-cured resin composite inlay repairs

A study was designed to simulate the repair of an indirect resin composite restoration with conventionally cured resin composite. Two-part specimens were prepared to test the diametral tensile strength of the repair interface between the base material of an indirectly cured resin composite (Herculite XRV) and repairs carried out with three directly cured materials (Herculite XRV, TPH, and Charisma). The repairs were carried out with and without use of the bonding resin for the repair material. The diametral tensile strengths of all repaired specimens were significantly less than those of bulk unrepaired specimens. There were no significant differences between the diametral tensile strengths of repaired blocks when the repair materials were used without bonding resin. The use of an intermediate layer of bonding resin significantly increased the bond strengths obtained when Herculite XRV and TPH were used for repair. There was no significant difference between the strength values of Herculite XRV and TPH, but Charisma exhibited the lowest strengths of repaired specimens.     

The effect of air abrasion on shear bond strength to dentin with dental adhesives

This study compared the effects of different dentin surface treatments on the shear bond strengths of three adhesive systems. The adhesive systems included a resin-modified glass ionomer, Fuji II LC, and two dentin bonding systems, One Step and Scotchbond Multi-Purpose Plus. The surface treatments compared for each adhesive system were as follows: 1) the controls, which were conditioned, 2) air abrasion at 120 psi without conditioning, 3) air abrasion at 160 psi without conditioning, 4) air abrasion at 120 psi with conditioning, and 5) air abrasion at 160 psi with conditioning. The KCP 1000 Whisperjet was used for all air-abrasive specimens. Controls for each adhesive material (Fuji II LC, One Step, Scotchbond Multi-Purpose Plus) were bonded using manufacturers' recommendations. Results showed that air abrasion significantly lowered bond strength of the resin-modified glass ionomer, conditioned or nonconditioned (P < 0.01). Air abrasion alone significantly lowered bond strengths of the dentin bonding agent systems (P < 0.01). However, air abrasion plus conditioning of the dentin surface resulted in bond strengths that were similar to the conditioned-only specimens (P < 0.01).     

An investigation on the shear bond strength of one dentin adhesive at two different dentin depths

The aim of this investigation was to study the effect of dentin depth and patient's age on the shear bond strength of one dentin adhesive (ART Bond), using an Instron Universal testing machine at a cross-head speed of 0.5 mm/min. Forty human molar teeth were used and were divided into two main groups, twenty each representing two age groups of patients, i.e., between 20 to 30 years and between 30-40 years of age. Every group was further subdivided into two subgroups of different dentin depths, i.e., superficial and deep. Results were recorded in Kg/Cm2 and converted into MPa units, then tabulated and statistically analyzed. A Duncan's range statistic test at P < or = 0.05 showed statistically significant differences between the bond strength values for both age groups at different dentin depths, with the superficial dentin showing higher bond values, and there were also statistically significant differences between the bond strength values of the two age groups at the same dentin depth, with the older age group showing higher bond values.     

Bond strength to crown and root dentin

PURPOSE: To investigate (1) the tensile bond strengths of four commercial dentin bonding systems to bovine crown and root dentin and (2) the structure of the hybrid layers for each system bonded to the two dentin substrates. MATERIALS AND METHODS: Superficial surfaces were exposed in bovine crown and root dentin. The teeth were embedded in plaster and a 3 mm diameter bonding area was demarcated. The four bonding systems used were All-Bond 2, Super-Bond D-Liner Plus, Clearfil Liner Bond II, and ProBond. Bonding procedures followed the manufacturers' instructions with the exception of Super-Bond D-Liner Plus where the primer was left in situ for 60 seconds. Tensile bond strengths were tested after 24-hour storage in 37 degrees C deionized water. Specimens were also prepared for SEM observation of the hybrid layer, after treatment with 10% phosphoric acid, and 10% phosphoric acid and 5% sodium hypochlorite. RESULTS: Statistically lower bond strengths to crown dentin when compared with root dentin were observed for All-Bond 2, whereas Liner Bond II showed the opposite (P < 0.01). Both ProBond and Super-Bond D-Liner Plus showed no statistical differences between crown and root dentin (P > 0.05). Hybrid layers could be observed for All-Bond 2, Liner Bond II and Super-Bond D-Liner Plus, with no apparent differences between the hybrid layers of crown and root dentin. In the case of ProBond, where the smear layer was not removed during the priming stage, it appeared that the primer had infiltrated and caused hybridization of the smear layer. The differences in bond strength were thought to be related to the different bonding mechanisms of each material, as well as possible variations in the crown and root dentin substrates.     

Cysteine and glutathione deficiency in AIDS patients: a rationale for the treatment with N-acetyl-cysteine

The purpose of this study was to determine the effect of accidental dentin primer contact with etched enamel on shear bond strength of composite resin to enamel. Four dentin bonding systems were included in this study: GLUMA Dentin Bond, Scotchbond, and Prisma Universal Bond 2 and 3. Eighty extracted human permanent anterior teeth were used and divided in eight test groups. The vestibular surfaces were ground and acid etched. For each dentin bonding system 10 samples were treated with dentin primer prior to placement of resin. Shear bond testing showed that enamel contact with dentin primer in the above two systems decreased the shear bond strength between composite and enamel by 31 to 44%.     

Snow on cholera--the special lecture in the Second British Epidemiology and Public Health Course at Kansai Systems Laboratory on 24 August 1996

The purpose of this study was to evaluate the resin-dentin interfacial morphology and shear bond strength of several new and experimental dentin bonding systems classified as single-bottle/total etch, multi-step/total etch, and self-etching. Class 1 and 5 cavities were prepared from freshly extracted permanent molars and restored with composite resin. Each bonded sample was cross sectioned and one-half was completely demineralized and deproteinized, while the other half was polished along the cut surface to permit measurement of the thickness of resin-infiltrated dentin layer (RIDL) within intertubular dentin (iRIDL) and around the peritubular walls (pRIDL) of resin tags by SEM. Shear bond strength was measured for all the systems 2 minutes after photocuring. SEM showed iRIDL and resin tags of different morphology depending on material and dentin location. The iRIDL was thinner in superficial dentin and thicker in deep dentin. Peritubular RIDL (pRIDL) was thinner than intertubular RIDL. Bond strength measurements varied from 12 to 21 MPa, depending on the materials used. Self-etching primer systems exhibited the highest bond strength, although one of the one-step/total etch systems also yielded very high values. The contribution of pRIDL to adhesion onto superficial dentin is limited by the small number of tubules. Single-component bonding agents produced SEM morphology and bond strengths similar to those of multi-step systems. Self-etching systems, despite their limited RIDL thickness, produced the highest immediate bond strengths. Bond strength did not correlate well with the thickness and morphology of RIDL.     

Bond strength of multi-step and simplified-step systems

PURPOSE: To measure and compare the in vitro shear bond strength (SBS) of the following three pairs of multi- and simplified-step dentin bonding systems: OptiBond vs. OptiBond FL, All-Bond 2 vs. One-Step, and Tenure vs. Tenure Quik. MATERIALS AND METHODS: 60 extracted human mandibular molars were sectioned perpendicular to the long axis 1 mm above the CEJ to expose the dentin bonding surface. After being wet-ground to 600 grit with SiC abrasive papers, rinsed and dried, the teeth were individually mounted in phenolic rings with epoxy resin, and randomly assigned into six equal groups of 10 each. The dentin surfaces were treated with the above mentioned dentin bonding systems, and a gelatin cylinder filled with resin composite (Pertac-Hybrid) was directly bonded to each pretreated surface. After 7-day storage in 37 degrees C water followed by thermocycling, the specimens were shear tested to failure on an Instron machine. Data were analyzed by independent t-tests, one-way ANOVA, and Duncan's Multiple Comparison tests at alpha = 0.05. RESULTS: Except for the pair Tenure/Tenure Quik, the differences between the pairs All-Bond 2/One-Step and OptiBond/OptiBond FL were statistically significant with All-Bond 2 and OptiBond FL yielding higher shear bond strength (P < 0.05). Findings of this study indicated that OptiBond FL was the only simplified-step system showing improved bond strength.     

Dentastic bond strength to dentin

PURPOSE: To evaluate the shear bond strength to the dentin of permanent teeth and failure site of Dentastic hydrophilic dentin bonding agent. MATERIALS AND METHODS: Forty permanent noncarious molar teeth stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on dentin to which the resin composite could be applied. After preparing the tooth surface, the teeth were stored in distilled water for 48 hours. They were then divided at random into four groups of 10 specimens each: Group 1: Dentastic, five coats of primer; Group 2: Dentastic, three coats of primer; Group 3: Dentastic, five coats of primer, light-cured adhesive before resin bonding; Group 4: Dentastic, three coats of primer, light-cured adhesive before resin bonding. All specimens were thermocycled (500x) and sheared in a testing machine. After shear testing, the debonded sites of all samples were examined with a stereomicroscope and a scanning electron microscope. RESULTS: The results in MPa were: Group 1: 22.63 +/- 6.24; Group 2: 23.35 +/- 5.14; Group 3: 23.58 +/- 5.66; Group 4: 27.26 +/- 8.22. ANOVA and Student-Newman-Keuls showed no statistically significant difference between the groups. In all groups, all specimens failed at the dentin (dentin cohesive failure = dentin fracture) or at the resin (resin cohesive failure = resin fracture). This means that the bond strength of the product is stronger than the cohesive strengths of the dentin and the resin.