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

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

Effects of phosphoric acid pretreatment and substitution of bonding resin on bonding effectiveness of self-etching systems to enamel

PURPOSE: To examine the etching efficacy of three self-etching systems to unconditioned enamel and to phosphoric-acid conditioned enamel using scanning electron microscopy (SEM), and to investigate the microtensile bond strength (muTBS) of three self-etching adhesives to unconditioned enamel used according to the manufacturers' instructions, on phosphoric-acid conditioned enamel, and when their different adhesives were replaced with a control resin after etching. MATERIALS AND METHODS: Clearfil SE Bond (CSE), Tyrian SPE/One-Step Plus (TY), and Adper Prompt L-Pop (AD) were employed. Scotchbond Multi-Purpose Plus (SBMP), an etch-and-rinse adhesive, was used as control. For muTBS evaluation, the buccal or lingual mid-coronal enamel of 30 molars was used. In the first group, self-etching adhesives were applied conventionally, according to manufacturers' directions (group C). A second group of specimens was etched with 35% phosphoric acid before application of the self-etching adhesives (group PA), and the third group of specimens was etched with the self-etching adhesives, rinsed, but bonded using a control bonding resin (group CR). Following restoration with Z250, they were sectioned into beams (0.8 mm2), and stressed to failure. Data were subjected to two-way ANOVA and Tukey's test. The etching efficacy of the self-etching adhesives, phosphoric acid, and prior phosphoric acid + SE application was evaluated under SEM. RESULTS: All self-etching adhesives applied as recommended by the manufacturers showed lower muTBS values than those obtained in PA and CR groups, although this difference was only significant for TY and AD. The means of all self-etching adhesives under PA and CR groups were similar to SBMP. The enamel conditioned with self-etching adhesive showed a less distinct pattern. CSE exhibited the mildest etching pattern. All self-etching adhesives applied after phosphoric acid exhibited a more retentive etching pattern. CONCLUSION: The bond strength values of low-pH self-etching adhesives can be improved by the adjunctive use of phosphoric acid or replacement of the bonding resin.     

Bond strengths of nonrinsing adhesives.

OBJECTIVE: The purpose of this study was to determine enamel and dentin bond strengths of a nonrinsing "all-in-one" adhesive and of a nonrinsing conditioner combined with a 1-bottle adhesive. METHOD AND MATERIALS: Specimens were obtained from 240 bovine teeth ground to expose enamel or dentin surfaces. Ten enamel and 10 dentin specimens were randomly assigned to each of 12 different combinations of adhesive system (Prompt L-Pop; no etch + Prime & Bond NT; NRC + Prime & Bond NT; 36% phosphoric acid + Prime & Bond NT; no etch + Prime & Bond 2.1; 36% phosphoric acid + Prime & Bond 2.1) and restorative material (resin composite; polyacid-modified resin composite ["compomer"]). After the application of the adhesive system, a No. 5 gelatin capsule filled with the restorative material was seated against the enamel or dentin surface. After 24 hours in distilled water at 37 degrees C, the specimens were thermocycled and the shear bond strengths were measured. RESULTS: For resin composite, etching with phosphoric acid resulted in the highest bond strengths to enamel. For compomer, the highest enamel bond strengths were achieved with both phosphoric acid and Prompt L-Pop. Treating dentin with Prime & Bond NT without etching provided the highest mean bond strength for composite. For compomer, treating dentin with Prime & Bond NT resulted in the highest mean bond strengths, regardless of the conditioner. CONCLUSION: Compomer and resin composite exhibited statistically similar bond strengths. Bond strengths to dentin were significantly lower than those to enamel.     

Adhesion of resin composite core materials to dentin

PURPOSE: This study determined (1) the effect of polymerization mode of resin composite core materials and dental adhesives on the bond strength to dentin, and (2) if dental adhesives perform as well to dentin etched with phosphoric acid as to dentin etched with self-etching primer. MATERIALS AND METHODS: Human third molars were sectioned 2 mm from the highest pulp horn and polished. Three core materials (Fluorocore [dual cured], Core Paste [self-cured], and Clearfil Photo Core [light cured]) and two adhesives (Prime & Bond NT Dual Cure and Clearfil SE Bond [light cured]) were bonded to dentin using two dentin etching conditions. After storage, specimens were debonded in microtension and bond strengths were calculated. Scanning electron micrographs of representative bonding interfaces were analyzed. RESULTS: Analysis showed differences among core materials, adhesives, and etching conditions. Among core materials, dual-cured Fluorocore had the highest bond strengths. There were incompatibilities between self-cured Core Paste and Prime & Bond NT in both etched (0 MPa) and nonetched (3.0 MPa) dentin. Among adhesives, in most cases Clearfil SE Bond had higher bond strengths than Prime & Bond NT and bond strengths were higher to self-etched than to phosphoric acid-etched dentin. Scanning electron micrographs did not show a relationship between resin tags and bond strengths. CONCLUSION: There were incompatibilities between a self-cured core material and a dual-cured adhesive. All other combinations of core materials and adhesives produced strong in vitro bond strengths both in the self-etched and phosphoric acid-etched conditions.     

Bond strength of different adhesive systems to dental hard tissues

This study compared the shear bond strengths of different adhesive systems to enamel and dentin of different depths. The adhesive systems used were: Single Bond one-bottle total-etch; AQ Bond one-step self-etching, Clearfil SE Bond two-step self-etching and Tyrian SPE/One-step Plus two-step self-etching. Eighty extracted non-carious human mandibular molars were mounted in self-curing resin and the occlusal surfaces were ground with a mechanical grinder to obtain flat occlusal enamel surfaces. After applying the adhesive systems, a plastic tube was attached to the enamel surfaces. The tube was filled with a universal hybrid resin composite, which was then polymerized. The specimens were stored in water at 37 degrees C for 24 hours. Shear bond testing was carried out using an Instron Universal testing machine with a crosshead speed of 1 mm/minute. The occlusal enamel of the 80 teeth was removed to determine the bond strengths of the adhesives to superficial dentin. To obtain deep dentin, the same teeth were ground deep towards the pulp, with the remaining dentin thickness approximately 0.7 mm. The adhesives and restorative material were then applied to the prepared dentin surfaces following the methodology described above. For occlusal enamel surfaces, the bond strength of Single Bond was significantly higher than the other adhesives. Single Bond, Clearfil SE Bond and Tyrian SPE/One-step Plus performed equally when bonded to superficial dentin; the lowest bond strength was obtained with AQ Bond. On deep dentin, the highest bond strengths were obtained with Clearfil SE Bond. For each adhesive system, shear bond strength to enamel was statistically higher than it was to either superficial or deep dentin. There were no significant differences between shear bond strengths to superficial versus deep dentin, regardless of adhesive.     

Bond strength of a self-etching adhesive system to caries-affected dentin

This in vitro study evaluated the microtensile bond strengths of sound versus caries-affected dentin using a self-etching adhesive system, Clearfil SE Bond, with or without additional acid pre-conditioning. Extracted human mandibular molars with occlusal caries extending halfway through the dentin were used. In the first group, the teeth were bonded with the self-etching adhesive Clearfil SE Bond according to the manufacturer's instructions. In the second group, prepared dentin surfaces were etched with 37% phosphoric acid prior to applying the same self-etching adhesive. After the bonding procedure, all specimens were built up with composite resin and stored in water for 24 hours. The teeth were serially sectioned vertically into 0.7-mm slabs and trimmed into an hourglass shape for measuring microtensile bond strength. Each specimen was attached to a Bencor device and stressed in tension at a crosshead speed of 1 mm/minute. Statistical analysis was performed using two-way ANOVA and the Tukey HSD test (p<0.05). The microtensile bond strengths of Clearfil SE Bond to sound dentin (32.9) were significantly higher than to caries-affected dentin (15.9). In the second group where acid etching was performed prior to applying Clearfil SE Bond, there were no statistically significant differences between the microtensile bond strengths of sound (19.2) and caries-affected dentin (16.3). While bond strengths to sound dentin were decreased by using additional acid etching prior to applying Clearfil SE Bond, this procedure revealed no statistically significant differences in bond strengths for the caries-affected dentin.     

Effect of calcium removal on dentin bond strengths.

OBJECTIVE: The purpose of this in vitro study was to determine the microtensile bond strengths (mu TBS) of 3 dental adhesives when applied to dentin decalcified with ethylenediaminetetraacetic acid (EDTA). The null hypothesis tested was that the removal of calcium from dentin would not influence the bond strengths. METHOD AND MATERIALS: Eighteen extracted human molars were cut in 2 equal halves. One half served as the control, having no EDTA treatment, while the other half was assigned to 1 of 3 periods (1 hour, 24 hours, or 100 hours) of decalcification with buffered 0.5 mol/L EDTA. Middle dentin was bonded with 1 of 3 dentin adhesive groups: a self-etching primer, Clearfil SE Bond (SE); an acetone-based total-etch adhesive, Prime&Bond NT (NT); and an ethanol- and water-based total-etch adhesive, Single Bond (SB). The specimens were restored with Z-250 resin composite and sectioned in 0.9 +/- 0.2 mm2 sticks that were tested in tensile mode. RESULTS: For each adhesive, the control group (not decalcified) resulted in statistically higher bond strengths than the treatment groups. For specimens that were not decalcified, SE and SB had statistically similar bond strengths, but both resulted in statistically higher bond strengths than NT. For specimens decalcified for 1 hour, SE resulted in statistically higher bond strengths than either SB or NT, which were ranked in the same statistical group. SE was the only dentin adhesive to result in measurable mu TBS after decalcification with EDTA for 24 hours, while SB/24 hour and NT/24 hour specimens debonded spontaneously prior to testing. All the specimens treated with EDTA for 100 hours debonded prior to testing. CONCLUSION: Three conclusions were drawn: (1) All 3 adhesive systems included in this project bonded significantly better to calcified than to decalcified dentin, regardless of their composition; (2) The self-etching primer-based adhesive ranked consistently equal to or better than the 2 total-etch-based adhesives, regardless of the EDTA decalcification time; and (3) Removal of calcium may be more detrimental for adhesives that rely on dentin acid etching than for adhesives based on self-etching primers.     

Aggressiveness of contemporary self-etching adhesives. Part II: etching effects on unground enamel.

OBJECTIVES: The aggressiveness of three self-etching adhesives on unground enamel was investigated. Ultrastructural features and microtensile bond strength were examined, first using these adhesives as both the etching and resin-infiltration components, and then examining their etching efficacy alone through substitution of the proprietary resins with the same control resins. METHODS: For SEM examination, buccal, mid-coronal, unground enamel from human extracted bicuspids were etched with either Clearfil Mega Bond (Kuraray), Non-Rinse Conditioner (NRC; Dentsply DeTrey) or Prompt L-Pop (ESPE). Those in the control group were etched with 32% phosphoric acid (Bisco) for 15s. They were all rinsed off prior to examination of the etching efficacy. For TEM examination, the self-etching adhesives were used as recommended. Unground enamel treated with NRC were further bonded using Prime&Bond NT (Dentsply), while those in the etched, control group were bonded using All-Bond 2 (Bisco). Completely demineralized, resin replicas were embedded in epoxy resin for examination of the extent of resin infiltration. For microtensile bond strength evaluation, specimens were first etched and bonded using the self-etching adhesives. A second group of specimens were etched with the self-etching adhesives, rinsed but bonded using a control adhesive. Following restoration with Z100 (3M Dental Products), they were sectioned into beams of uniform cross-sectional areas and stressed to failure. RESULTS: Etching patterns of aprismatic enamel, as revealed by SEM, and the subsurface hybrid layer morphology, as revealed by TEM, varied according to the aggressiveness of the self-etching adhesives. Clearfil Mega Bond exhibited the mildest etching patterns, while Prompt L-Pop produced an etching effect that approached that of the total-etch control group. Microtensile bond strength of the three experimental groups were all significantly lower than the control group, but not different from one another. When the self-etching adhesives were replaced with the control adhesive after etching, bond strengths of NRC/Prime&Bond NT and Prompt L-Pop were not significantly different from that of the control group, but were significantly higher than that of Clearfil Mega Bond. SIGNIFICANCE: Both etching efficacy and strength of the resins are important contributing factors in bonding of self-etching adhesives to unground enamel.     

Microtensile bond strength of contemporary adhesives to primary enamel and dentin

The purpose of this study was to assess bond strength of three self-etching and two total-etch adhesive systems bonded to primary tooth enamel and dentin. MATERIALS AND METHODS: Forty extracted primary human molars were selected and abraded in order to create flat buccal enamel and occlusal dentin surfaces. Teeth were assigned to one of the adhesive systems: Adper Scotch Bond Multi Purpose, Adper Single Bond 2, Adper Prompt L-Pop, Clearfil SE Bond and AdheSE. Immediately to adhesive application, a composite resin (Filtek Z250) block was built up. After 3 months of water storage, each sample was sequentially sectioned in order to obtain sticks with a square cross-sectional area of about 0.72 mm2. The specimens were fixed lengthways to a microtensile device and tested using a universal testing machine with a 50-N load cell at a crosshead speed of 0.5 mm/min. Microtensile bond strength values were recorded in MPa and compared by Analysis of Variance and the post hoc Tukey test (a = 0.05). RESULTS: In enamel, Clearfil SE Bond presented the highest values, followed by Adper Single Bond 2, AdheSE and Adper Scotch Bond Multi Purpose, without significant difference. The highest values in dentin were obtained with Adper Scotch Bond Multi Purpose and all other adhesives did not present significant different values from that, except Adper Prompt L-Pop that achieved the lowest bond strength in both substrates. Adper Scotch Bond Multi Purpose and Adper Single Bond 2 presented significantly lower values in enamel than in dentin although all other adhesives presented similar results in both substrates. CONCLUSIONS: contemporary adhesive systems present similar behaviors when bonded to primary teeth, with the exception of the one-step self-etching system; and self-etching systems can achieve bond strength values as good in enamel as in dentin of primary teeth.     

Dentin bond strengths of simplified adhesives: effect of dentin depth

The objective of this study was to compare the shear bond strength of 3 simplified adhesive systems applied on shallow vs deep dentin. For superficial dentin, 30 human molars were sectioned with a diamond saw to expose dentin immediately below the dentoenamel junction. For deep dentin, 30 molars were sectioned 3 mm below the dentoenamel junction. The teeth were mounted, polished to 600-grit, and randomly assigned to 3 groups (n=10): Single Bonda and OptiBond Solo, total-etch adhesives, and Clearfil Liner Bond 2V, a self-etching primer adhesive. Adhesives were applied, the restorative material Filtek Z250 inserted in a No. 5 gelatin capsule, and light-cured. After 24 hours in water at 37 degrees C, shear bond strength was measured with an Instron at 5 mm/min. The data were analyzed with 2-way ANOVA and Duncan's post-hoc test. The results showed the following shear bond strengths (mean +/- SD in MPa): Single Bond/superficial dentin = 22.1 +/- 2.8; Single Bond/deep dentin = 14.2 +/- 7.0; OptiBond Solo/superficial dentin = 18.9 +/- 4.1; OptiBond Solo/deep dentin = 18.4 +/- 4.8; Clearfil Liner Bond 2V/superficial dentin = 21.0 +/- 7.4; Clearfil Liner Bond 2V/deep dentin = 17.6 +/- 5.9. There were no significant differences between mean shear bond strength for the factor "adhesive system" (P>.822). The Duncan's test showed that Single Bond resulted in higher shear bond strength on superficial dentin than on deep dentin. The mean shear bond strength for Clearfil Liner Bond 2V and OptiBond Solo were not influenced by dentin depth. When data were pooled for dentin depth, deep dentin resulted in statistically lower bond strengths than superficial dentin (P<.01). The influence of dentin depth on shear bond strength depends on the specific composition of the dentin adhesive.     

Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces.

OBJECTIVES: The aim of this study was to evaluate the bonding of four commercially available adhesive systems to ground and intact enamel surfaces. METHODS: Extracted human teeth were used to measure the microtensile bond strength to enamel and a field-emission scanning electron microscopy (FE-SEM) was used to observe the bonded interface and the effect of the surface conditioning of each material. Intact buccal enamel surfaces were cleansed with tooth paste using a rotary dental brush, and the ground enamel surfaces were prepared by reducing approximately 0.5 mm from the buccal enamel surfaces using a high-speed diamond bur. One-Step (OS, Bisco), Single Bond (SB, 3M), Clearfil Liner Bond II (LBII, Kuraray), and Tokuso Mac Bond II (MBII, Tokuso) were evaluated for their ability to bond to enamel. RESULTS: There was no significant difference in bond strengths between the materials when they were applied to ground enamel surfaces (p > 0.05). However, the bond strengths of the self-etching systems, LBII and MBII, had significantly lower bond strengths to intact enamel than the bonding systems OS and SB using phosphoric acid etching (p < 0.05). FE-SEM revealed that the etching pattern of self-etching primers was not deep enough to obtain good penetration of bonding resin when applied to intact enamel surfaces. CONCLUSIONS: Phosphoric acid etching produced good resin adhesion to ground and intact enamel. The self-etching/self-priming systems also produced good adhesion to ground enamel, but had lower bond strengths to intact enamel.     

Primary dentin etching time,bond strength and ultra-structure characterization of dentin surfaces

Objectives

To evaluate the effect of shortening the etching time on roughness, microhardness and bond strength of three adhesive systems to primary tooth dentin.

Methods

Flat dentin surfaces from primary molars were randomly assigned to six experimental groups. Three different adhesive systems were used: an etch-and-rinse adhesive (Single Bond), a two-step self-etching (Clearfil SE Bond), and a one-step self-etching (One-Up Bond F) adhesive. In half of the specimens, the recommended etching time was used, in the other half the etching time was 50% reduced. After applying the adhesive, resin composite build-ups were constructed and stored in a humid environment for 24 h at 37 °C. Specimens were sectioned into 1 mm² beams and tested for microtensile bond strength (MTBS). Debonded surfaces were analyzed by scanning electron microscopy (SEM). Additional surfaces were conditioned for microhardness measurements (KHN) and for atomic force microscopy (AFM) analysis. Intertubular and total surface roughness (Ra) were recorded. Results were analyzed with ANOVA and Student–Newman–Keuls tests (P < 0.05).

Results

Single Bond and Clearfil SE Bond showed higher MTBS than One-Up Bond F. Bond strength and intertubular roughness increased when Single Bond and One-Up Bond F were used with a reduced etching time. For Clearfil SE Bond no differences in MTBS were detected when reducing the etching time. The application of phosphoric acid, Clearfil SE Bond primer and One-Up Bond F decreases dentin microhardness.

Conclusions

Shortening One-Up Bond F application time and reducing the etching time of phosphoric acid to one-half of the manufacturer's recommended etching time when using Single Bond are recommended when bonding to primary dentin.     

Influence of phosphoric acid pretreatment on self-etching bond strengths

Purpose : The purpose of this investigation was to evaluate the influence of phosphoric acid pretreatment on shear bond strength of two self-etching bonding systems to enamel and dentin. Materials and Methods: Forty-eight extracted third human molar teeth were mounted, embedded into polystyrene resin, polished with 600-grit aluminum oxide papers, and randomly divided into four groups ( n = 12): group 1–Clearfil Liner Bond® 2V (Kuraray Co. Ltd., Osaka, Japan); group 2–One Up Bond F® (Tokuyama Corp., Tokyo, Japan); group 3–phosphoricacid (Condicionador Dental Gel®, Dentsply Ind. Com. LTDA, Rio de Janeiro, Brazil) and Clearfil Liner Bond 2V; group 4–phosphoric acid and One Up Bond F. In groups 3 and 4 the substrate was pre-etched for 15 seconds with 37% phosphoric acid, rinsed, and dried with an air stream. In all groups adhesive systems were applied according to manufacturers' instructions and light cured; then a restorative composite resin (TPH Spectrum®, Dentsply Ind. Com. LTDA) was placed in a polytef matrix and cured. The specimens were stored in humidity for 7 days at 37°C. The shear bond strength test was performed in a universal test machine with a crosshead speed of 0.5 mm/min. All procedures were repeated for the dentin evaluation. Mean values were analyzed with two-way analysis of variance and Duncan tests ( p < .05).
Results : The values obtained are listed in decreasing order: enamel–group 3 = 24.6 MPa, group 4 = 23.6 MPa, group 1 = 19.2 MPa, group 2 = 8.5 MPa; dentin–group 1 = 17.2 MPa, group 2 = 16.1 MPa, group 4 = 13.1 MPa, group 3 = 11.3 MPa.
Conclusions : Under the conditions of this study, enamel etching with 37% phosphoric acid provided statistically significant higher shear bond strength values, regardless of the adhesive system. However, in dentin, for Clearfil Liner Bond 2V, phosphoric acid pretreatment negatively affected bond strength values.     

Self-Etching Primers – an Alternative to the Conventional Acid Etch Technique?

MATERIAL AND METHODS: The aim of the present in vitro study was to evaluate the bonding capacity of three self-etching primers (Clearfil SE Bond [SE], Clearfil Liner Bond 2V [CLB], Novabond [NOVA]) to enamel. Two adhesive systems with a separate phosphoric acid etching procedure (Gluma Comfort Bond [GLU], Kurasper F [KU]) served as controls. 60 human incisors were used to evaluate shear bond strengths of composite cylinders to enamel. RESULTS: Significant differences were found between the groups (p < 0.001). The mean value for groups GLU, KU, CLB and SE was 24 MPa. The shear bond strength recorded for the Novabond system was significantly lower (17 MPa). CONCLUSION: The results of the present investigation indicate that enamel bonding especially with the self-etching primers CLB and SE is as effective as conventional phosphoric acid etching.     

Effect of bonding variables on the shear bond strength and interfacial morphology of a one-bottle adhesive

This study's objectives were: 1) to determine the combination of bonding procedures (with or without acid etching, moist or dry substrate, one or two applications of primer/adhesive) that would produce the highest shear bond strength of Prime & Bond and Dyract AP and 2) to characterize the resin-dentin/enamel interface produced by these bonding procedures. Ninety-six bovine incisors were randomly assigned to eight groups for shear bond testing to enamel (n = 6) and dentin (n = 6). Prime & Bond and Dyract AP were applied and cured following manufacturers' instructions. Shear bond testing was conducted in a Universal Testing Machine. Thirty-two bovine incisors were sectioned to produce blocks with enamel and dentin, then bonded in pairs for evaluation of interfacial morphology. They were polished and argon ion-etched using a high-speed argon ion-etching machine and examined by SEM. The groups where enamel was etched, kept moist or dry and received a single application of Prime & Bond produced the highest shear bond strength. Dentin bond strengths were high in the groups where dentin was etched and kept moist. The number of Prime & Bond applications had no effect on dentin bond strength. Acid etching results in better adaptation of Prime & Bond to enamel and dentin regardless of whether moisture is present.     

Effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic bracket retention

The purpose of this study was to test the effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic treatment. Bovine incisors were either acid-etched or laser-treated. An orthodontic bracket was attached on each treated surface using one-step dentin adhesive and self-curing resin. Tensile bond strength was then evaluated. In addition, the surface morphology of specimens treated with phosphoric acid/laser and self-etching primer, as well as the cross-section of enamel-primer-resin interfaces, were observed. One-Up Bond F-treated specimens after Er:YAG laser ablation showed statistically similar tensile bond strength (9.9 +/- 1.3 MPa) to that of phosphoric acid-etched specimens (11.8 +/- 1.7 MPa). Surface roughness and thickness of the enamel-primer-resin interfaces did not much affect the tensile bond strength of the tested specimens. In conclusion, Er:YAG laser ablation achieved clinically acceptable level of tensile bond strength when used with One-Up Bond F.     

Bonding to enamel and dentin using self-etching adhesive systems.

OBJECTIVES: This study investigated the effectiveness of three different dentin adhesive systems on the adhesion of resin composite to both dentin and enamel. METHOD AND MATERIALS: The flat dentin and enamel surfaces of 60 extracted human molar teeth were exposed by wet grinding with 600-grit silicon carbide paper. One total-etch self-priming adhesive system (Prime & Bond NT), one two-step self-etching primer adhesive system (Clearfil SE Bond), and one "all-in-one" self-etching adhesive system (Prompt L-Pop) were evaluated. Each bonding system was applied according to the manufacturer's instructions and followed by composite (TPH Spectrum) application. Twenty-four hours after bonding, the teeth were subjected to shear testing. There were 10 replicates for each group. RESULTS: Prompt L-Pop exhibited significantly higher bond strength values to enamel (27 +/- 4.2 MPa) than all other groups. There were no statistically significant differences for shear bond strength to dentin among adhesives. Prompt L-Pop showed the statistically significantly higher bond strength to enamel than dentin. There were no statistically significant differences between the enamel and dentin bond strengths of Clearfil SE Bond and Prime & Bond NT. CONCLUSIONS: The self-etching adhesive systems produced high bond strengths to human coronal dentin and ground enamel surfaces. These materials seem to be very promising for further clinical applications, and the results are very encouraging for the clinical success of these simplified adhesive systems. The self-etching adhesive systems produced even better bond strengths to both enamel and dentin than conventional total-etch systems, especially the "all-in-one" system, which produced the highest bond strength to enamel.     

Shortening of primary dentin etching time and its implication on bond strength

OBJECTIVE: The aim of this study was to investigate the influence of shortening the etching time on the bond strength of a conventional and a self-etching primer adhesive system used in primary tooth dentin. METHODS: Flat dentin surfaces were obtained from 24 primary molars, randomly assigned to 4 experimental groups. The adhesive systems Single Bond and Clearfil SE Bond were applied in two groups according to the manufacturers' recommendations. In the other two groups, the adhesives were applied after half-time of acid etching, 7 s for Single Bond and 10 s for Clearfil SE Primer. Resin crowns were built up and after 24 h storage in water at 37 degrees C, the teeth were sectioned to produce beams with cross-sectional area of approximately 0.49 mm2. Specimens were tested in tension at 0.5 mm/min until failure. Fractured specimens were analyzed to determine the failure mode. RESULTS: Tensile bond strengths for Single Bond in primary dentin were higher than for Clearfil SE Bond. Shortening of acid etching time improved bond strength only for Single Bond, while no statistically significant difference was observed for Clearfil SE Bond when both etching times were compared. SIGNIFICANCE: No detrimental effect on bond strength was observed when the time of acid etching was shortened in 50%. Shortening the time for a procedure in a small child without compromising the quality of the work is a very important finding for the practicing pediatric dentist.     

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 using self-etching primer for bonding orthodontic brackets

Questions over the use of self-etching primers with composite resin adhesives in the bonding of orthodontic brackets remain unsolved. In addition, there are no previous reports on the efficacy of self-etching primers with resin-modified glass ionomer cements for bonding orthodontic brackets in orthodontic dentistry. The purpose of this study was to determine the shear bond strengths of orthodontic brackets bonded with one of four protocols: (1) a composite resin adhesive used with 40% phosphoric acid, (2) the same composite resin used with Megabond self-etching primer, (3) a resin-modified glass ionomer cement adhesive used with 10% polyacrylic acid enamel conditioner, and (4) the same resin-modified glass ionomer cement used with Megabond self-etching primer. The appearance of the tooth surfaces after acid etching or priming was observed with a field-emission scanning electron microscope (FE-SEM). When used with resin-modified glass ionomer cement, Megabond self-etching primer gave no significantly different shear bond strength compared with polyacrylic acid etching. But when used with composite resin adhesive, Megabond self-etching primer gave significantly lower shear bond strength than phosphoric acid etching. However, the shear bond strength of orthodontic brackets bonded with composite resin adhesive after Megabond priming was almost the same as that of brackets bonded with resin-modified glass ionomer cement after polyacrylic acid etching. FE-SEM observation revealed that Megabond self-etching primer produced less dissolution of enamel surface than did phosphoric acid and polyacrylic acid etching. Megabond self-etching primer may be a candidate for bonding orthodontic brackets using the resin-modified glass ionomer cement for minimizing the amount of enamel loss.