Dentin regional bond strength of self-etch and total-etch adhesive systems

OBJECTIVES: To evaluate the microtensile bond strength (MTBS) of self-etch (with or without H(3)PO(4)-etching) and total-etch bonding systems bonded to different regions of dentin. METHODS: Long flat dentin cavity preparations extending from top-crown to root-apex within the same tooth were performed and bonded: using two-step (Clearfil SE Bond/SEB, Resulcin Aqua Prime/RES) and one-step (Etch & Prime 3.0/EP, One-Up Bond F/OUB, Prompt L-Pop/PLP, Solist/SOL and Futurabond/FUT) self-etch adhesives; these same adhesives were also applied following H(3)PO(4)-etching of dentin and finally two more groups were bonded with total-etch adhesives (Single Bond/SB and Prime & Bond NT/PBNT). Build-ups of resin composite were constructed incrementally to ensure sufficient bulk for the MTBS test and the different regions of dentin were identified by painting with different colours on the top of the resin composite. Specimens were sliced into beams and tested in tension. ANOVA and multiple comparisons tests were used (p<0.05). RESULTS: Regardless of the tested dentin region, SEB attained the highest MTBS to smear layer-covered surfaces (i.e., coronal dentin: 42.7MPa), while H(3)PO(4)-etching of dentin hampered bonds (i.e., coronal dentin: 27.7MPa). When bonding with PBNT, SB, RES, EP, PLP, SOL and FUT, MTBS was similar for different dentin regions. H(3)PO(4)-etching of dentin did not alter the attained MTBS. SIGNIFICANCE: SEB yielded the highest MTBS to all regions of dentin. When bonding to parallel-cut dentin, previous H(3)PO(4)-etching of dentin did not increase MTBS and differences in bond strength among dentin regions were absent.     

Resistance of ten contemporary adhesives to resin-dentine bond degradation

OBJECTIVES: To evaluate resin-dentine bond degradation after 1 year of water storage. METHODS: Human dentine surfaces were bonded with two etch-and-rinse self-priming adhesives (Single Bond/SB and Prime & Bond NT/PBNT), three 2-step self-etching adhesives (Clearfil SE Bond/SEB, Resulcin Aqua Prime/RES and Non-Rinse Conditioner with Prime & Bond NT/NRC-PBNT), and five 1-step self-etching adhesives (Etch & Prime 3.0/EP, Prompt L-Pop/PLP, Solist/SOL, Futurabond/FUT and AQ Bond/AQ). Adhesives were applied according to manufacturers' instructions. Composite build-ups were constructed and the bonded teeth were stored (24 h, 6 months, 1 year) in distilled water at 37 degrees C. After storage, the intact teeth were sectioned into beams and all specimens were tested for microtensile bond strengths (MTBS). ANOVA and multiple comparisons tests were applied at alpha = 0.05. Fractographic analysis of debonded beams was performed using scanning electron microscopy. RESULTS: SB, PBNT and SEB attained the highest MTBS, regardless of the storage period. A significant decrease in MTBS was observed after 6 months for SOL. After 12 months the only groups that did not reduce bond strength were SB and SEB. Bonded specimens in NRC-PBNT, RES and FUT produced pre-testing failures after 12 months, and MTBS could not be measured. CONCLUSIONS: The resistance of resin-dentine bonds to degradation is material-dependent. When the enamel-resin interface is preserved, the etch-and-rinse adhesives and the mild 2-step self-etch adhesive SEB exhibited the best resin-dentine bond durability. Those tested self-etching adhesives having a pH < or 1 and using water or acetone as solvent attained catastrophic bond failure after 1 year of water storage.     

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 self-etching primers to enamel and dentin of primary teeth.

PURPOSE: The objective of this in vitro study was to evaluate the tensile bond strength of three self-etching primers to human primary enamel and dentin. METHODS: Forty (40) freshly extracted primary molars were sectioned bucco-lingually and embedded in self-curing acrylic resin with the facial or lingual surfaces exposed. The specimens were wet ground to 600 grit SiC paper to expose a flat enamel or dentin surface. The materials tested were: Prompt L-Pop (LP2, ESPE), Clearfil SE Bond (CSE, Kuraray America), Etch and Prime 3.0 (EP, Degussa) anda control, Prime and Bond NT (NT, Dentsply/Caulk). The adhesive systems were applied according to the manufacturers' instructions. An inverted, truncated cone of composite (Pertac II, ESPE) with a 2-mm bonding diameter was cured using a polytetrafluoroethylene jig. The specimens were debonded in tension using a universal testing machine (Instron) at a crosshead speed of 0.5 mm/min. RESULTS: Analysis of variance (ANOVA) showed significant differences existed between the four systems and two surfaces. To enamel of primary teeth, Prime and Bond NT had significantly higher bond strength (25.9 MPa) than when bonding with the three acidic primers Prompt L-Pop (18.5 MPa), Etch and Prime 3.0 (19.3 MPa) and Clearfil SE Bond (18.7 MPa). Complete bond failures occurred with Prompt L-Pop and Etch and Prime 3.0 to dentin of primary teeth. With a mean of 39 Mpa, the bond strength to dentin of primary teeth with Clearfil SE Bond was significantly higher than with Prime and Bond NT (12.5 MPa). CONCLUSIONS: The results of this in vitro study show that the four adhesive systems tested bonded effectively to enamel of primary teeth, but only CSE achieved adequate bond strengths to dentin of primary teeth.     

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.     

Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives

The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers’ instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24 h, 37 °C) or thermocycled (5,000 cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α = 0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24 h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin–dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.     

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.     

Microtensile bond strengths of two adhesive resins to discolored dentin after amalgam removal

Studies have reported the discoloration of dentin beneath amalgam restorations. The purpose of this study was to test the hypothesis that the bond strengths of adhesive resins to this discolored dentin are lower than those to normal dentin, and are related to the presence of metallic ions or corrosion products. Amalgam-filled extracted human teeth were used. After the removal of amalgam, the discolored dentin and surrounding normal dentin were bonded with Single Bond or Clearfil SE Bond and tested for microtensile bond strengths. The bond strengths of Single Bond and Clearfil SE Bond to normal dentin were greater than to discolored dentin. Clearfil SE Bond demonstrated higher bond strength to normal dentin than did Single Bond. However, no differences were found between the bond strengths to the discolored dentin of both adhesives. Elemental micro-analysis revealed various amounts of tin in all discolored dentin.     

Effects of adhesive liner and provisional cement on the bond strength of nickel/chrome/beryllium alloy cemented to dentin.

OBJECTIVE: Treating teeth with adhesive agents before placing a provisional restoration can prevent tooth sensitivity. This study evaluated the bond strength of resin cements to dentin treated with 2 adhesive agents and 2 provisional cements. METHODS AND MATERIALS: Extracted human molars were prepared by exposing dentin and were treated with either Prime & Bond NT or Clearfil SE Bond. After a simulated impression technique, the teeth were provisionalized with either a eugenol or noneugenol temporary cement. Teeth were cleaned for bonding by either mechanical removal of the cement or use of an acid conditioner. Panavia F and Calibra resin cements were used to cement nickel/chrome/beryllium alloy to the tooth surfaces, and the specimens were debonded. Mean shear bond strengths for each group were calculated. RESULTS: Mean shear bond strengths ranged from 26.6 +/- 5.8 MPa for Calibra bonded to dentin treated with Prime & Bond NT, a noneugenol cement, and mechanically cleaned, to 10.6 +/- 4.4 MPa for Panavia F bonded to unlined (no adhesive) dentin treated with a eugenol cement and mechanically cleaned. Of the 14 groups tested, significant differences were observed related to the adhesives and resin cements. Both temporary cements reduced the bond to dentin not treated with a resin adhesive. Use of an acid conditioner for cleaning the temporary cement also reduced bond strengths in all groups. CONCLUSIONS: Placement of a dentin adhesive before provisionalization may prevent the temporary cement from affecting the bond of the final resin cement to the tooth. For the products used in this study, use of phosphoric acid to clean the tooth surface is not recommended.     

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.     

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.     

Bond strengths of one- and two-step self-etch adhesive systems

STATEMENT OF PROBLEM: One-bottle self-etching adhesives have been introduced that combine the etchant, primer, and adhesive into a single bottle in an effort to reduce the number of bonding steps. Limited research has been conducted comparing the efficacy of 1-bottle and 2-bottle self-etching adhesives. PURPOSE: This investigation evaluated the microtensile bond strength (MTBS) of 3 one-step self-etching adhesives, 2 two-step self-etching adhesives, and a total-etch adhesive. A secondary objective was to evaluate the effect of an intermediary layer of elastic resin on the MTBS of 2 of the self-etching adhesives. MATERIAL AND METHODS: The MTBS of 3 one-step self-etching adhesives (G-Bond, iBond, and Clearfil S(3)), 2 two-step self-etching adhesives (Clearfil SE and Optibond Solo Plus Self-Etch), and a total-etch adhesive (Prime & Bond NT) was evaluated. Microtensile bond strength (MPa) was determined using composite resin (Herculite XRV) cylinders bonded to the dentin surface of human third molars (n=24) using 6 bonding agents. Each bonded tooth specimen was longitudinally sectioned to produce bar-shaped specimens with a square cross-sectional nominal bond area of 1.4 mm(2) (n=20). Bonded specimens were stored in distilled water at 37 degrees C +/- 2 degrees C for 72 hours, during which time they were subjected to thermal cycling (1500 cycles, in water baths of 5 degrees C and 55 degrees C, for a dwell time of 30 seconds). Testing was performed on a universal testing machine at a crosshead speed of 1.0 mm/min. One-way ANOVA, Ryan-Einot-Gabriel-Welsh multiple range test, and Wald chi square test, each using an overall alpha=.05, were performed on all data. Low-power (x20) microscopic examination of the bond failure was observed for each specimen. RESULTS: The 1-way ANOVA (P<.001) and Ryan-Einot-Gabriel-Welsh multiple range test (P<.05) showed significant differences between the mean MTBS values for several of the bonding agents tested. The Wald chi square test of the Weibull distribution showed significant differences between adhesives (P<.001). CONCLUSION: Of the bonding agents tested, significantly higher MTBS was obtained with the total-etch 2-stage adhesive. The results of this study suggest that there are similar bond strengths between the 1- and 2-bottle self-etch adhesives.     

Bond strength of self-etching adhesives to dental hard tissues

Since most cavity preparations show not only areas of exposed enamel and superficial dentin but also of deep dentinal areas, it would be desirable to use a dental adhesive which can obtain equally good bond strength to these hard tissues. The objective of this study was to measure the bond strength of self-etching adhesives to enamel and superficial and deep dentin. Human molars were ground to expose a surface of enamel or superficial (2.0-2.5 mm distance to pulp) or deep dentin (0.5-1.0 mm), embedded in acrylic resin and assigned to three groups (total n=90). The adhesives tested were: Clearfil SE Bond (SE), Prompt L-Pop (LP), and Etch&Prime 3.0 (EP). After application of the adhesives, an inverted, truncated cone of composite (Pertac II, ESPE) was cured. After storage, specimens were debonded in tension at a cross-head speed of 0.5 mm/min. The median tensile bond strength values to enamel were SE 29.1 MPa, LP 22.4 MPa, and EP 21.5 MPa. The median bond strengths for superficial dentin were SE 27.3 MPa, LP 8.4 MPa, and EP 3.2 MPa. The median bond strengths for deep dentin were SE 20.2 MPa, LP 5.7 MPa, and EP 1.3 MPa. The adhesives tested bonded effectively to enamel, but only SE achieved promising bond strengths to superficial and deep dentin.     

Effect of solvent and rewetting time on dentin adhesion.

OBJECTIVE: The purpose of this in vitro study was to determine the influence of solvent and rewetting time on microtensile dentin bond strengths of four dentin adhesives. METHOD AND MATERIALS: Sixty human molar specimens were divided into four dentin adhesive treatment groups: (1) a water-based total-etch dentin adhesive, EBS Multi; (2) an ethanol-based total-etch adhesive, Excite; (3) an acetone-based total-etch adhesive, Prime & Bond NT; and (4) an ethanol- and water-based total-etch adhesive, Single Bond. For each dentin adhesive, three specimens were assigned to five dentin moisture conditions. Specimens were tested in the tensile mode. RESULTS: When adhesives were applied to moist dentin, bond strengths varied from 26.2 MPa for Prime & Bond NT to 29.5 MPa for Single Bond without any statistical differences. When applied to dentin that had been dried for 15 seconds, Prime & Bond NT and Excite resulted in the lowest mean bond strengths, but they were statistically similar to each other (7.9 and 8.3 MPa, respectively). Single Bond resulted in a mean bond strength of 12.7 MPa, which was significantly lower than that of EBS Multi (24.1 MPa). For the latter, all mean bond strengths were statistically similar when some amount of moisture was present on the surface. For the other three adhesives, mean bond strengths returned to the range obtained on moist dentin only when dentin was rewet for 30 seconds. CONCLUSION: Bond strengths upon rewetting depend on the type of solvent in the bonding system, and rewetting time.     

Influence of the substrate and load application method on the shear bond strength of two adhesive systems

The difficulty with comparing data obtained from different research centers calls for the standardization of laboratory procedures. This in vitro study compared the shear bond strength (SBS) of two adhesive systems--a self-etching system, Etch&Prime 3.0 and a one-bottle total-etch system, Single Bond--using two methods of load application (orthodontic edge wire loop and knife-edge blade). The hypothesis of substrate influence on the results obtained for both tests was also investigated. Twenty-four recently extracted human teeth were embedded in PVC tubes using acrylic resin and divided into two groups (n=12). A proximal surface of each tooth was wet-ground flat to expose dentin. Etch&Prime 3.0 and Single Bond adhesive systems were applied according to the manufacturers' instructions, and cone-shaped restorations were then built using Z100 resin composite. After storage in distilled water at 37 degrees C for 24 hours, the specimens were submitted to SBS testing using an orthodontic edge wire loop. The same teeth were again embedded in PVC tubes using acrylic resin and the other proximal surface was wet-ground flat to expose dentin. The specimens were prepared as explained above, and after storage in distilled water under the same previous conditions, they were submitted to SBS testing using a knife-edge blade. Two-way ANOVA and Tukey's tests were performed to determine any statistically significant differences among testing conditions. Results indicated that SBS values obtained for Etch&Prime 3.0 were significantly lower than Single Bond for both methods of load application (p<0.001). Regarding the load application method, statistically significant higher values (p<0.01) were obtained for Etch&Prime 3.0 when the knife-edge blade was used, whereas, no significant difference was observed between the two methods for Single Bond. There was a significant correlation between the bond strength values obtained on the same tooth (p<0.05). SEM examination found that Etch&Prime 3.0 demonstrated narrower tags than Single Bond. Moreover, the peritubular dentin was not adequately decalcified when Etch&Prime 3.0 was used.     

Influence of light-activated and auto- and dual-polymerizing adhesive systems on bond strength of indirect composite resin to dentin

STATEMENT OF PROBLEM: Clinicians must be aware of the bonding effectiveness of auto- and dual- polymerizing adhesive systems before choosing the material and technique of cementing inlay/onlays to dentin. An inadequate choice may compromise the success of indirect restorations. PURPOSE: This study compared the microtensile bond strength (MTBS) of indirect composite resin bonded to dentin by light-activated, autopolymerizing, and dual-polymerizing adhesive systems. MATERIAL AND METHODS: Occlusal dentin surfaces of 36 human third molars were exposed and flattened. Teeth were assigned to 1 of the following 6 groups (n=6) of adhesive luting systems: 2 dual-polymerizing systems (Scotchbond Multipurpose Plus/Rely X [SBMP] and Prime & Bond NT Dual Cure/Enforce [PBDC]); 1 autopolymerizing system (ED Primer/Panavia F [EDP]); and 3 light-activated systems (control groups) (Adper Single Bond/Rely X [SB], Prime & Bond NT/Enforce [PB], and Clearfil SE Bond/Panavia F [CF]). The restorative materials were applied according to manufacturer's directions. A 2-mm-thick prepolymerized composite resin (Clearfil APX) disc was cemented with the resin cements on the bonded dentin. Teeth were stored in water at 37 degrees C for 24 hours. Afterwards, teeth were sectioned both mesial-distally and buccal-lingually to obtain multiple bonded beam specimens with 0.8 mm(2) of cross-sectional area. Each specimen was tested in tension at a crosshead speed of 0.5 mm/min until failure. Data (MPa) were analyzed by 1-way analysis of variance and the Tukey post hoc test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy. RESULTS: Mean MTBS values (MPa) for experimental groups were as follows: SBMP, 32.89 +/- 3.26(a); SB, 26.74 +/- 7.45(ab); PB, 26.11 +/- 4.48(ab); CF, 25.30 +/- 6.42(ab); EDP, 16.82 +/- 5.53(bc); PBDC, 11.20 +/- 5.89(c) (P<.001). Groups with similar lowercase letters were not significantly different. Failure pattern of fractured specimens varied according to the polymerization mode. CONCLUSION: The autopolymerizing system and one of the dual-polymerizing systems were as effective as the light-activated systems in bonding indirect composite restorations to dentin.     

Evaluation of microleakage using different bonding agents

This study evaluated microleakage in vitro using different bonding agents. Forty-two freshly extracted caries-free human teeth were randomly divided into seven groups of six teeth and restored with different adhesive systems: Single Bond, Prime&Bond NT, Excite, Durafill Bond, Etch&Prime 3.0, Prompt L-Pop and Vitremer as the control group. All groups were treated according to manufacturers' instructions. Class V cavities were prepared on buccal and lingual surfaces (3 x 2.5 x 1.5 mm) of each tooth (12 restorations per group), with gingival margins in dentin. The teeth were restored with Charisma resin composite. After finishing and polishing with Denco-Flex disks, the teeth were thermocycled for 200 cycles (5 degrees C-55 degrees C +/- 2 degrees C, 60-second dwell time). Apical foramina and surfaces around restorations were coated with nail varnish, stained in 50% AgNO3 solution for 12 hours and longitudinally sectioned. Microleakage was evaluated with a stereomicroscope. Marginal penetration was scored on a 0-4 scale. Statistical analysis using the Kruskal-Wallis test revealed significant (p < or = 0.05) leakage at dentin margins for all adhesive systems when compared to the control. Except for Durafill Bond, no significant difference was found between the self-etching adhesives and one-bottle adhesives.     

五种牙本质粘结系统微拉伸强度的比较

目的比较不同类型自酸蚀牙本质粘结系统的粘结强度,为临床应用提供参考。方法选择4种自酸蚀粘结系统Clearfil S3Bond,i Bond,Clearfil SE Bond,XenoⅢ,1种全酸蚀粘结系统Single Bond2,用微拉伸法测试这些粘结系统的粘结强度并进行比较。结果全酸蚀粘结剂Single Bond2的微拉伸强度最高,与自酸蚀粘结剂粘结强度有显著差异（P〈0.05）。自酸蚀粘结剂i Bond,S3Bond,XenoⅢ两两之间粘结强度无显著差异（P〉0.05）。SE Bond的粘结强度显著高于i Bond,S3Bond和XenoⅢ（P〈0.05）。结论第五代牙本质粘结剂具有较强的粘结强度,但第七代牙本质粘结剂临床操作更为方便。     

Single-step, self-etch adhesives behave as permeable membranes after polymerization. Part III. Evidence from fluid conductance and artificial caries inhibition

PURPOSE: To test the hypothesis that formation of inhibition zones by bonded restorations in artificially-induced carious dentin lesions is related to the permeability of the self-etch adhesives. METHODS: Fluid conductance of four single-step self-etch adhesives (Prompt L-Pop, Etch&Prime 3.0, One-Up Bond F and Reactmer Bond), and a control two-step self-etch adhesive (UniFil Bond) were measured after sound dentin surfaces were:(1) acid-etched; (2) polished to produce smear layers; (3) bonded with the adhesive; each at 20 cm hydrostatic pressure (hp). Osmotic fluid conductance was also determined for the bonded dentin after immersion in 4.8 M CaCl2 at 0 cm hp. For artificial caries inhibition, a non-fluoride releasing (NFR) two-step self-etch adhesive (UniFil Bond) and a fluoride-releasing (FR) single-step adhesive (Reactmer Bond) were used in combination with a NFR composite (Metafil CX) or a FR restorative material (Reactmer Paste). Artificial caries were induced in these restorations, from which 120 +/- 10 microm thick sections and the effect of caries inhibition were quantitatively assessed with polarizing light microscopy and image analysis. RESULTS: Fluid conductance after bonding with the single-step adhesives Prompt L-Pop and Etch&Prime 3.0 were not significantly different from those recorded from smear layer-covered dentin. Although better seals were achieved with One-Up Bond F and Reactmer Bond, fluid conductance at 20 cm hp was significantly higher than the two-step self-etch adhesive UniFil Bond. Osmotic conductance at 0 cm hp were not significantly different from normal fluid conductance at 20 cm hp. The sizes of artificial carious lesions in UniFil Bond were significantly higher irrespective of whether a FR or NFR composite was used. Significant reduction in lesion size occurred in Reactmer Bond with the use of a NFR composite, and even more so with the use of a FR composite.     

脱矿牙本质与四种粘接剂的粘接强度测试及粘接界面观察

目的比较脱矿牙本质与4种全酸蚀或自酸蚀粘接剂的粘接强度及粘接界面超微结构的差异,以期对临床治疗有所指导。方法选择20颗面龋坏的离体磨牙,在龋显示剂的指示下去除牙本质龋的感染层,保留脱矿牙本质。平齐龋洞洞底平面,去除冠向牙体组织,作为粘接面。选择临床常用的2种全酸蚀粘接剂:材料A(All Bond2)、材料B(Prime&BondNT)和2种自酸蚀粘接剂:材料C(ClearfilSEBond)、材料D(XenoⅢ),分别按说明书要求粘接。用慢速锯将样本牙切为粘接面积约0.9mm×0.9mm的长方体试件。体视显微镜下将试件分为正常牙本质组和脱矿牙本质组,用微拉伸测试仪检测粘接强度。扫描电镜观察各组试件粘接界面的超微形态。结果方差分析提示牙本质类型和粘接剂对微拉伸粘接强度的影响均有统计学意义(P<0.05)。对正常牙本质,不同粘接剂的微拉伸粘接强度差异无统计学意义(P>0.05);对于脱矿牙本质,材料D的微拉伸粘接强度较其他粘接剂明显降低(P<0.05)。扫描电镜下观察脱矿牙本质的混合层多孔稀疏,树脂突短少,无侧枝形成。结论对脱矿牙本质,本项实验中全酸蚀粘接剂的粘接强度优于自酸蚀粘接剂。