Polymerization shrinkage-strain and microleakage in dentin-bordered cavities of chemically and light-cured restorative materials.

OBJECTIVES: The aim of this study was to evaluate in vitro the relationship between polymerization shrinkage and microleakage in dentin-bordered restorations. METHODS: Four light-cured restorative materials in combination with their respective dental bonding agents (DBA) were investigated: Tetric Ceram/Syntac classic (Vivadent), Solitaire/Gluma Solid bond (Heraeus Kulzer), Definite/Etch & Prime 3.0 (Degussa), Solitaire 2/Gluma Solid bond (Heraeus Kulzer). The chemically cured resin Degufill sc microhybrid (Degussa) in combination with ART Bond (Coltène) was also included. Polymerization shrinkage of the restorative materials was measured using three different methods (dilatometer, linometer, buoyancy method) and analyzed with ANOVA. For the determination of microleakage, caries-free human molars were embedded in acrylic resin and subsequently abraded with a wet abrasion machine to produce four level dentin surfaces. One hundred sixty cavities (3 mm diameter/1.5 mm deep) were randomly assigned to four groups of equal size. The groups were restored without (group 1 and 2) and with DBA (group 3 and 4), and either not subjected (group 1 and 3) or subjected (group 2 and 4) to 2000 cycles from 5-55 degrees C. Each group was further divided into five material subgroups of eight cavities each. Microleakage was determined using a dye penetration test assessed at depths of 200, 400 and 600 microm into the fillings. Data were analyzed with the Kruskal-Wallis and the Mann-Whitney test. RESULTS: All three methods of measuring polymerization shrinkage (PS) generated the same, statistically secured ranking for the four light-cured restorative materials: PS Definite < PS Tetric Ceram < PS Solitaire 2 < PS Solitaire. In the microleakage study, only a few statistically significant differences were observed. Etch & Prime 3.0/Definite in group 3 and Solid Bond/Solitaire 2 in group 4 tended to exhibit the least microleakage. Correlation coefficients between aggregated shrinkage and microleakage data were 0.3 for group 3 and -0.2 for group 4. SIGNIFICANCE: The results do not suggest any correlation between polymerization shrinkage and microleakage in dentin of direct adhesive restorations.     

Effect of solvent type on microtensile bond strength of a total-etch one-bottle adhesive system to moist or dry dentin

This study evaluated the effect of organic solvent (acetone or ethanol) on the microtensile bond strengths (MTBS) of an adhesive system applied to dry and moist dentin. Sixteen extracted human third molars were ground to expose a flat occlusal dentin surface and acid etched for 20 seconds (20% phosphoric acid gel, Gluma Etch 20 Gel, Heraeus/Kulzer). After rinsing the acid etchant, an ethanol-based one-bottle adhesive system was applied to the mesial half of the occlusal dentin surface. An acetone-based, one-bottle adhesive system was applied to the distal half of the ground dentin surface. The teeth were randomly assigned to groups. In Group 1, the etched dentin was thoroughly air dried and an ethanol-based one-bottle adhesive system was applied (Gluma Comfort Bond, Heraeus/Kulzer) (GCB). In Group 2, the etched dentin was thoroughly air dried and an acetone-based one-bottle adhesive system was applied (Gluma One Bond, Heraeus/Kulzer)(GOB). In Group 3, excess moisture was removed after acid etching, leaving a moist dentin surface and a one-bottle ethanol-based adhesive was applied (Gluma Comfort Bond). In Group 4, excess moisture was removed after acid etching, leaving a moist dentin surface and an acetone-based adhesive was applied (Gluma One Bond). A hybrid resin composite (Venus, Heraeus/Kulzer) was applied to the bonded surface in four 1-mm increments and light cured according to manufacturer's directions. The specimens were then sectioned with a slow-speed diamond saw in two perpendicular directions to obtain sticks with a cross-section of 0.5 +/- 0.05 mm2. The microtensile bond strength (MTBS) test was performed with a Bencor device in an Instron machine at a crosshead speed of 0.5 mm/minute. The data were subjected to a two-way ANOVA and Scheffé Post hoc test (p < 0.05). The experimental MTBS measured for dry dentin were Group 1 = 37.0 +/- 10.6 and Group 2 = 34.7 +/- 9.0 in MPa (mean +/- SD); and on moist dentin, Group 3 = 50.7 +/- 11.0 and Group 4 = 38.5 +/- 10.5 in MPa (mean +/- SD). The ethanol based adhesives resulted in higher MTBS than acetone-based adhesive (p < 0.008) and bonding to moist dentin resulted in higher MTBS (p < 0.001). GCB applied on moist dentin resulted in statistically higher bond strengths than the other groups. The highest MTBS were achieved with the use of an ethanol-based adhesive to moist dentin.     

Effect of self-etching adhesives on dentin permeability in a fluid flow model

STATEMENT OF PROBLEM: Numerous self-etching bonding systems exist, with composition differing from one product to another. It is important for the clinician to know if they are all equally effective, and whether they provide an effective seal between dentin and restorative materials. PURPOSE: This study was designed to measure the hydraulic conductance of physiologic saline across dentin after application of various self-etching bonding systems or of a 1-bottle adhesive system preceded by a phosphoric acid etch. MATERIAL AND METHODS: One hundred extracted noncarious human third molars from patients 18-25 years old were used for this study. Dentin disks were cut from crown segments parallel to the occlusal surface at the top of the pulp cavity. The 100 disks, each 1 mm thick, were divided into 10 groups (n=10 per group), each of which was treated with 1 of 9 self-etching systems-AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, Etch & Prime 3.0, Prime & Bond NRC Nt, One-Up Bond F, optiBond solo Plus Self Etch, Prompt L-Pop, or Xeno III-or a control bonding system (Prime & Bond NT) preceded by a phosphoric acid etch. Hydraulic conductance, the volume of fluid transported across a known area of surface (0.28 cm2) per unit time under a unit pressure gradient (200 cm H2O), was analyzed for the adhesive systems using a fluid flow apparatus (Flodec). First, both sides of each specimen were etched with 36% phosphoric acid for 30 seconds, and the hydraulic conductance was measured every 30 seconds for 15 minutes. The initial set of measurements served as the reference value for each specimen. The measurements were repeated when a smear layer had been formed and, finally, after 1 of the 10 bonding systems had been applied. The data were analyzed using a 1-way ANOVA and Duncan's multiple range test (alpha=.05). RESULTS: The control 1-bottle adhesive used with a phosphoric acid pre-etch did not provide the largest reduction in penetration (42.3%). The greatest mean reduction (68.9%, P<.05) was observed with the self-etching product Xeno III. The mean reduction for the other materials tested were: One-Up Bond F, 60.5%; AdheSE, 58.2%; Etch & Prime 3.0, 56.8%; Adper Prompt L-Pop, 51%; optiBond solo Plus Self Etch, 45%; Clearfil SE Bond, 35.5%, Prime & Bond NRC Nt, 16.4%; and Prompt L-Pop, 16.3%. CONCLUSION: Within the limitations of this study, the self-etching systems tested produced different reductions in dentin permeability. For some, the reduction was much greater than the decrease in dentin permeability provided by the bonding system with a phosphoric acid pre-etch; for others, the reduction was small.     

The effect of different types of flowable restorative resins on microleakage of Class V cavities

This study evaluated the microleakage of Class V cavities restored with three different types of flowable resin restorative material and compared the effects of using their respective manufacturer's dentin adhesive or a different brand. Class V cavities with the occlusal margin in enamel and the gingival margin in dentin were prepared on the buccal and lingual surfaces of 48 non-carious human molars. The teeth were randomly assigned to three equal groups of 16. The first eight teeth in each group were restored with one of the flowable restorative materials (Filtek Flow, Dyract Flow, Admira Flow) using the manufacturer's recommended dentin adhesive (Single Bond, Prime & Bond NT, Admira Bond), and the remaining eight molars were restored using a different brand of dentin adhesive (Gluma Comfort Bond). The samples were thermocycled 200 times (5 degrees C-55 degrees C) with a one-minute dwell time. They were then immersed in a 2% basic fuchsin solution for 24 hours, sectioned and analyzed by stereomicroscopy. There was no statistically significant difference at the occlusal margins for either restoration used with its respective dentin adhesive. At the gingival margins, there was a significant difference among all groups. Flowable ormocer (Admira Flow/Admira Bond) displayed the least leakage at the gingival margins. When these flowable restoratives were used with a different brand of dentin adhesive, statistically significant differences were observed both on enamel and dentin. None of the restoratives tested fully prevented leakage at the gingival margins. No significant differences in microleakage were observed among the restorative materials used with respect to the manufacturer's dentin adhesive or a different brand except for Admira Flow restorative at the gingival margins. The gingival margins had significantly more microleakage than the occlusal margins (p < 0.05) except in the Admira Flow group, where microleakage at the occlusal and gingival margins was almost equal.     

Microtensile bond strengths of seven dentin adhesive systems.

OBJECTIVES: The purpose of this study was to evaluate the microtensile bond strengths of seven dentin adhesive systems (Solid Bond, EBS-Multi, PermaQuik, One Coat Bond, Gluma One Bond, Prime & Bond NT/NRC and Clearfil Liner Bond 2V) and their respective fracture modes. METHODS: Superficial occlusal dentin of extracted human molars was exposed, finished with wet 600-grit silicon carbide paper, and a block of resin composite bonded with the above adhesives according to the manufacturers' instructions. The teeth were kept in tap water for 24 h at 37 degrees C, sectioned to obtain three or four bar-shaped specimens, which were then shaped to an hour-glass form of 1.2 +/- 0.02 mm diameter. The specimens were stressed at a crosshead speed of 1 mm/min until rupture of the bond. The mean bond strengths were compared using one-way ANOVA and LSD tests. The frequency of fracture modes was compared using Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: Mean microtensile bond strengths ranged from (17.8 +/- 7.0) MPa for Solid Bond to (36.0 +/- 8.1) MPa for Clearfil Liner Bond 2V. The bond strength of Clearfil Liner Bond 2V and PermaQuik (30.8 +/- 8.5 MPa) were not significantly different, and were higher than all other materials. Bond strengths of Solid Bond (17.8 +/- 7.0) MPa, EBS-Multi (18.7 +/- 5.0) MPa, One Coat Bond (21.9 +/- 5.6) MPa, and Gluma One Bond (23.4 +/- 5.2) MPa were not significantly different. SEM examination indicated that Solid Bond, EBS-Multi and One Coat Bond showed no significant difference in failure modes but were significantly different from PermaQuik, Prime & Bond NT/NRC and Clearfil Liner Bond 2V. SIGNIFICANCE: The self-etching primer system, Clearfil Liner Bond 2V, provided the simplest bonding technique, and together with PermaQuik exhibited greatest bond strength to dentin.     

Microscopic evaluation of dentin interface obtained with 10 contemporary self-etching systems: correlation with their pH

This study investigated micromorphological differences in the hybridized complex formed using 10 commercially available self-etch bonding systems. In addition, the influence of the pH of the primer of these adhesives was evaluated. The self-etching systems tested were AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, Etch&Prime 3.0 (Degussa, Germany), Prime & Bond NT Non Rinse Conditioner (Dentsply, Konstanz, Germany), One-Up Bond F, OptiBond Solo Plus Self Etch, Prompt L-Pop and Xeno III. One hundred non-carious human third molars were used. The teeth were divided into two groups of 50 and prepared for evaluation by optical microscopy or scanning electron microscopy. The specimens in each group were further divided into 10 subgroups of five specimens each to evaluate the 10 bonding systems. The pH of the primers of the bonding systems was measured. The results demonstrated morphological differences at the interface, depending on adhesive composition. The differences mainly concerned thickness of the hybrid layer, the absence or presence of microscopic voids at the adhesive-composite interface and whether the dentinal tubuli were completely sealed. The pH was not the determining factor conditioning the action of the self-etching adhesives.     

Restoration interface microleakage using one total-etch and three self-etch adhesives

This study evaluated the efficacy of a total-etch and three self-etch adhesives in reducing microleakage after three months water storage and thermocycling. Thirty freshly extracted caries-free human premolars and molars were used. Class V standardized preparations were performed on the facial and lingual surfaces, with the gingival margin placed 1 mm below the CEJ. The teeth were randomly divided into four groups; Group I: Xeno III one-step self-etch adhesive (Dentsply/Caulk), Group II: Prime & Bond NT total-etch adhesive (Dentsply/Caulk), Group III: i-Bond one-step self-etch adhesive (Heraeus Kulzer) and Group IV: Clearfil SE Bond two-step self-etch adhesive (Kuraray Medical). The teeth were restored using 2 mm increments of shade A2 resin composite (Esthet-X, Dentsply/Caulk). Each layer was cured using the Spectrum 800 curing light (Dentsply/Caulk) for 20 seconds at 600mW/cm2. The teeth were stored in distilled water for 90 days. Samples were thermocycled 500x between 5 degrees C and 55 degrees C with a dwell time of 30 seconds, then placed in a 0.5% methylene blue dye solution for 24 hours at 37 degrees C. Samples were sectioned longitudinally and evaluated for microleakage at the occlusal and gingival margins under a stereomicroscope at 20x magnification. Dye penetration was scored: 0 = no penetration; 1 = partial dye penetration along the occlusal or gingival wall; 2 = dye penetration along the occlusal or gingival wall; 3 = dye penetration to and along the axial wall. A Mann-Whitney test was used to demonstrate significantly more dye penetration in Group III than in the other groups at both the occlusal and gingival scores (p < 0.0001). When comparing the occlusal and gingival scores for each group, the Wilcoxon Rank test showed no significant difference in dye penetration for Xeno III (p > 0.05), Prime & Bond NT (p = 0.059) and I Bond (p = 0.083), and Clearfil SE Bond yielded more dye penetration at the occlusal than at the gingival wall (p = 0.001).     

Inter-crystallite nanoretention of self-etching adhesives at enamel imaged by transmission electron microscopy

The purpose of this in vitro study was to analyse the mode of action of self-etching adhesive systems when applied for resin-to-enamel bonding. Transmission electron microscopy was used to investigate the enamel-resin interface after application of non-rinsing self-etching adhesive systems based on phosphoric acid estered methacrylates (Clearfil Liner Bond 2, Clearfil SE Bond, Etch & Prime 3.0 and Resulcin AquaPrime) compared with conventional phosphoric acid etching and bonding (Heliobond). Non-decalcified ultrathin sections from the interface between enamel and self-etching adhesive systems revealed a 1.5-3.2-microm deep enamel surface layer characterized by a less-dense arrangement of enamel crystallites separated from each other by nanometer-sized spaces. A 1.5-3.2-microm wide, netlike resinous structure was observed in corresponding decalcified specimens, indicating that self-etching priming agents dissolve the peripheral and central part of the enamel crystallites, while simultaneously promoting inter- and intra-crystallite monomer infiltration. A similar pattern, but greater depth (6.9 microm) of enamel surface hybridization was found in the phosphoric acid-etched and bonded specimens. The nanoretentive interlocking between enamel crystallites and resin could explain the potential of self-etching adhesive systems in resin-to-enamel bonding despite the less distinct enamel etching pattern observed in scanning electron microscopy investigations.     

Self-etching primer vs phosphoric acid: an alternative concept for composite-to-enamel bonding.

The purpose of this in vitro study was (1) to investigate the composite-to-enamel bond strength and (2) to analyze the marginal adaptation of resin composite restorations in class 2 cavities using three self-etching priming agents in comparison to conventional phosphoric acid etching and bonding application. In the first part of the study 24 extracted bovine incisors were embedded in acrylic resin and ground flat with 800-grit paper. The following three self-etching priming agents/composite resins were applied to the enamel surfaces of six teeth each: Clearfil Liner Bond 2/Clearfil AP-X (Group I), Etch & Prime 3.0/Degufill mineral (Group II), Resulcin AquaPrime + MonoBond/Ecusit (Group III). In Group IV Ecusit-Mono/Ecusit was used after enamel etching with phosphoric acid (37%). Shear bond strength values measured on a T22 K testing machine at a crosshead speed of 1 mm/min were: 24.2 +/- 3.0 MPa (Group I), 21.9 +/- 1.4 MPa (II), 34.0 +/- 3.6 MPa (III), and 26.3 +/- 1.8 MPa (IV). ANOVA revealed significant (P < 0.05) differences in shear bond strength between groups, except comparison of Group I and II, and Group I and IV. In the second part of the study 24 standardized class 2 cavity preparations with the approximal box extending 1 mm above the CEJ were prepared in extracted human molars. Enamel margins were beveled and the teeth were divided into four groups of six teeth each. Cavities were restored using the self-etching priming agents Clearfil Liner Bond 2 (Group I), Etch & Prime 3.0 (Group II), and Resulcin AquaPrime + MonoBond (Group III). In Group IV composite resin restorations were placed after 37% phosphoric acid etching and bonding application (Ecusit-Mono). Quantitative SEM analysis of the marginal adaptation of the restorations after thermocycling (5-55 degrees C, 2500 cycles) and mechanical loading (100 N, 500,000 cycles) revealed excellent, gap-free margins in 91.2% (Group I), 93.0% (Group II), 92.0% (Group III), and 92.5% (Group IV) of the restorations' approximal area. There were no statistically significant differences between the four groups (P < 0.05). In conclusion, results of the present in vitro study indicate that use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in composite-to-enamel bonding restorative techniques.     

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.     

Effect of oxygen inhibition of self-etching adhesives on enamel-dentin polymer bond

PURPOSE: To determine effects of light curing of self-etching adhesives under ambient air or nitrogen on inhibition depths, enamel and dentin bond strengths, and marginal adaptation in dentin cavities. MATERIALS AND METHODS: The adhesives investigated were: AQ Bond (AQB, Sun Medical; Kyoto, Japan), iBond (IBO, Heraeus Kulzer; Hanau, Germany), One-Up Bond F II (OUB, Tokuyama; Tokyo, Japan), and Prompt L-Pop (PLP, 3M/ESPE; Seefeld, Germany). Inhibition layer thickness (ILT) was microscopically measured on 3 disk-shaped specimens each. Shear bond strengths (SBS) on enamel and dentin (n = 8) were determined after 10 min and 24 h water storage of bonded composite specimens (Venus, Heraeus Kulzer). The marginal adaptation of bonded Venus restorations in cylindrical dentin cavities was microscopically evaluated after 10 min of specimen storage (n = 8) in water. The data were statistically analyzed using parametric and nonparametric ANOVA and post-hoc tests at p < 0.05. RESULTS: Adhesive curing under air revealed significant ILT (microm) differences: IBO (4) < AQB (8) < PLP (12) < OUB (23). Upon curing in nitrogen atmosphere, no inhibition occurred with AQB, IBO, and PLP, and < 3 microm for OUB. SBSs on enamel after 10 min or 24 h did not differ according to curing atmospheres (p > 0.05). On dentin, SBSs were higher after curing under N2 (p < 0.05). Irrespective of the curing atmosphere, marginal adaptation was good for AQB and IBO and poor for PLP; OUB revealed significantly smaller gaps under N2 than under air curing. CONCLUSION: Oxygen inhibition of the four self-etching adhesives investigated had no or only moderate effects on bonding efficacy to enamel and dentin.     

Comparison of microleakage on one composite etched with phosphoric acid or a combination of phosphoric and hydrofluoric acids and bonded with several different systems

STATEMENT OF PROBLEM: There are no data available on whether or to what extent hydrofluoric acid affects the marginal integrity of dentin-bonded composite restorations when it is used instead of phosphoric acid in the total-etch technique. PURPOSE: This in vitro study examined the etching effects of phosphoric acid versus a combination of phosphoric and hydrofluoric acid by evaluation of microleakage in a composite restoration bonded with different dentin adhesive systems. MATERIAL AND METHODS: Extracted teeth (n = 90) containing 2 class II preparations, mesial occlusal (MO) and distal occlusal (DO) standarized (cervical margins in dentin) were perfused with Ringer solution and etched in 1 of 2 ways: with phosphoric acid only or with phosphoric combined with hydrofluoric acid. Different dentin bonding agents were then applied (Etch & Prime 3.0, Optibond Solo, Prime & Bond NT, Scotchbond 1, Syntac Single Component, or Syntac Sprint; (n = 15 for each etching material)). The preparations were restored with a hybrid composite (Herculite XRV) and submitted to 5000 thermocycles (5 degrees C to 55 degrees C) to simulate the in vivo situation. Microleakage was assessed with 2% methylene blue diffusion for 24 hours. Dye penetration was calculated as a percentage of the total length of the gingival margins of the preparation with light microscopy at original magnification x 32. The results were analyzed with the Kruskal-Wallis multiple comparison z-value assay (alpha = .05). RESULTS: Differences in dye penetration were significant, both as a function of the dentin adhesive and the conditioning mode applied. In the specimen groups conditioned with phosphoric acid, Optibond Solo (54% +/- 44%) and Syntac Sprint (74% +/- 39%) demonstrated the lowest penetration values. Higher values were obtained for Prime & Bond NT (81% +/- 34%), Scotchbond 1 (83% +/- 31%), Etch & Prime 3.0 (85% +/- 33%), and Syntac Single Component (95% +/- 16%), with no significant differences (alpha=.05) between specimen groups. The best results were obtained for Syntac Sprint (24% +/- 26% dye penetration) after conditioning with a mixture of phosphoric and hydrofluoric acid. The least favorable result was obtained for Optibond Solo (65% +/- 31%). It was significantly different from Prime & Bond NT (76% +/- 37%), Scotchbond 1 (85% +/- 29%), and Etch & Prime 3.0 (88% +/- 24%). Syntac Single Component (75% +/- 32%) was significantly different from Syntac Sprint. Syntac Single Component and Syntac Sprint exhibited significantly better results when conditioned with a combination of phosphoric acid and hydrofluoric acid than with phosphoric acid only. CONCLUSION: Within the limitations of this in vitro study, total-etching water-based (Syntac Single Component) and acetone-based (Syntac Sprint) bonding agents with a combination of phosphoric acid and hydrofluoric acid led to significant reductions (alpha=.05) in dye penetration compared to phosphoric acid conditioning only. Ethanol-based dentin bonding agents (Etch & Prime 3.0, Optibond Solo, and Scotchbond 1) were not significantly influenced by the type of conditioner used.     

In vivo evaluation of microleakage from composites with new dentine adhesives

The purpose of this study was to investigate microleakage in V class composite restorations with total etch versus self-etching adhesives. Experiments were conducted in vivo and were also evaluated interfacial micromorphology. Forty class V cavities were prepared on the buccal surfaces of teeth in three healthy dogs. The cavities were randomly assigned into five groups of eight teeth and restored with one of the following adhesive systems: Etch and Prime 3.0/Definite flow/Definite, Prompt L-pop/Filtek flow/P-60, Admira bond/Admira Flow /Admira, Bond 1/Flow it/Alert, Stae/Wave/Glacier. After 60 days the animals were killed and the teeth were extracted. The teeth were then immersed in a solution of 0.5% basic fuchsin dye for 24 h, sectioned and scored for microleakage. Features of the tooth/restoration interfaces were also examined using Scanning electron microscopy. Student-Newman-Keuls and one-way anova revealed significance differences among the groups for overall wall scores (P < 0.05). The total-etch adhesives revealed significantly less microleakage scores than the self-etching adhesive systems tested. Wilcoxon Signed Ranks Test revealed significant differences between the occlusal and gingival microleakage scores for each adhesive restorative system, with the exception of Admira (P < 0.05).     

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.     

Microleakage of Class V resin composites placed using self-etching resins: effect of prior enamel etching.

OBJECTIVE: The purpose of this study was to compare the seal along dentin and enamel margins produced by 3 self-etching resin bonding systems to that of an etch-and-rinse adhesive system. Potential improvement in adaptation along enamel margins through the experimental use of conventional enamel etching prior to application of the self-etching adhesives was also evaluated. METHOD AND MATERIALS: Class V resin composite restorations were placed in prepared cavities in extracted third molars using 3 self-etching dentin adhesive systems: Adper Prompt L-Pop (3M Espe), iBond GI (Heraeus Kulzer), and Tyrian SPE (Bisco), and an etch-and rinse adhesive, Adper ScotchBond Multi-Purpose (3M Espe). A group of teeth also underwent conventional enamel etching prior to use of the self-etching products. The restored teeth were thermocycled, subjected to a dye challenge, and sectioned. The sections were scored using an ordinal leakage scale (n = 20). Ranked data were analyzed using a 2-way analysis of variance and Tukey multiple comparison. RESULTS: When used as directed, there were no significant differences along dentin margins for any of the adhesives, but Adper Prompt and iBond demonstrated significantly greater leakage than the etch-and-rinse product along enamel margins. The incidence of enamel margin leakage decreased significantly for the same 2 products when enamel etching preceded use of the resin. Enamel etching increased the leakage along dentin margins for all 3 self-etching products, but not significantly. CONCLUSION: Considerable improvement of all classes of dentin-adhesive resin systems is still needed. Practitioners should await further clinical trials before adopting use of self-etching resins, especially for large occlusal restorations.     

In vitro fracture resistance of root-filled teeth using new-generation dentine bonding adhesives

AIM: To compare the fracture resistance of root-filled premolar teeth restored with new-generation dentine bonding adhesives. METHODOLOGY: Sixty extracted single-rooted human maxillary premolar teeth were used. Access cavities were prepared, and the roots were instrumented with K-files to an apical size 50 using a step-back technique. Root fillings were accomplished using gutta percha (Sure-Endo, Seoul, Korea) and AH Plus root canal sealer (Dentsply DeTrey, Konstanz, Germany) using the lateral condensation technique. The teeth were then randomly divided into six groups of 10 teeth each. A mesiodistocclusal (MOD) cavity was prepared in the teeth to the level of the canal orifices so that the thickness of the buccal wall of the teeth measured 2 mm at the occlusal surface and 3 mm at the cemento-enamel junction. Preparations were restored using the following adhesive systems: Etch & Prime 3.0 (Degussa AG, Hanau, Germany), Clearfil SE Bond (Kuraray, Osaka, Japan), Prompt L-Pop (ESPE, Seefeld, Germany), Panavia F (Kuraray, Osaka, Japan), Optibond Plus (Kerr, Orange, CA, USA) and Admira Bond (Voco, Cuxhaven, Germany); all preparations except those of the Panavia F and Admira Bond groups were further restored with resin composites. The Panavia F group was restored with amalgam and the Admira Bond group with Ormocer (Voco, Cuxhaven, Germany). The teeth were mounted in a Universal Testing Machine (Hounsfield, Surrey, UK), and the buccal walls were subjected to a slowly increasing compressive force until fracture occurred. The force of fracture of the walls of each tooth was recorded and the results in the various groups were compared. Statistical analysis of the data was accomplished using one-way anova. RESULTS: There was no significant difference in the fracture resistance of any of the test groups. CONCLUSIONS: In this laboratory study, the type of dentine bonding agents had no influence in the fracture resistance of teeth.     

Does chemomechanical caries removal affect dentine adhesion?

The purpose of this study was to determine whether shear bond strengths (SBS) to chemomechanically excavated dentine (Carisolv) differed from the SBS after conventional caries removal (bur). The following adhesive systems were used: Dyract AP/NRC/Prime & Bond NT; Dyract AP/Prime & Bond NT; Tetric Ceram/ Syntac SC; Tetric Ceram/Syntac SC (no etch) (TC 2); Definite/Etch & Prime 3.0; Definite/experimental. One-hundred and twenty human molars with occlusal caries were assigned to 12 groups. Sequential caries removal was controlled with laser fluorescence. After water storage, the samples were tested in a single-plane shear test assembly. The results demonstrated differences between the bonding systems, whereas the mode of caries removal had no consistent effect. If total etch technique was neglected, the results of the composite resin (TC 2) indicated a tendency to higher SBS in the Carisolv group (18.6 +/- 4.6 MPa) compared with conventional treatment (14.1 +/- 3.9 MPa). The present data demonstrate that chemomechanical caries removal has no adverse effect on bonding of modern adhesive systems to dentine. Smear layer-dissolving or -modifying bonding systems could potentially benefit from chemomechanical pretreatment.     

Inlay shading effect on the photopolymerization kinetic of a dental composite material used as bonding system in an indirect restoration technique.

OBJECTIVES: To define the inlay shading effect on the polymerization levels and kinetics of a light activated bonding system for an indirect restoration technique. MATERIALS AND METHODS: For the bonding system, an adhesive: Excite (Ivoclar-vivadent) and a composite: Z250 (3M-ESPE, St Paul Minnesota, USA) were investigated. A Demetron (Kerr USA) light curing unit was used. The composite inlay blocks of 2 mm thick were used for the experiment (Artglass A2 Heraeus, Kulzer, Dormagen, Germany). The bonding composite was photocured using a 2 mm composite inlay block as a shielding system while the adhesive was shielded by a 2.3 mm thick wafer, composed of the inlay material and the previously cured bonding composite. The kinetics and levels of polymerization were measured by a differential scanning calorimeter technique (DSC 25, Mettler, Orange, CA, Toledoh, küsnacht, switzerland). RESULTS: The inlay shielded dental composite reaches a significantly lower level of polymerization compared to the unshielded composite. Inlay shielded composite, has a slower polymerization kinetic compared to unshielded composite. The resin adhesive shielded by the inlay-composite wafer reaches polymerization values not significantly different from those of the unshielded adhesive. SIGNIFICANCES: The degree of cure of the light-cured composite resins for use as a base for indirect composite restorations, may be severely reduced as a result of inlay shielding.     

Quantitative evaluation of microleakage in Class V cavities using one-bottle and self-etching adhesive systems

The aim of this in vitro study was to evaluate quantitatively the microleakage in Class V cavities restored with one-bottle and self-etching adhesive systems with and without previous acid etching. Two one-bottle adhesive systems (Single Bond and Prime & Bond 2.1) and one self-etching adhesive system (Clearfil Mega Bond) were used in this study. One hundred and twenty sound human premolar teeth were randomly divided into 6 groups, and 20 Class V restorations were prepared in the root dentin to test each bonding system. Each bonding system was used with and without acid etching. Specimens were prepared, dyed with 2% methylene blue, sectioned, triturated, and evaluated with an absorbance spectrophotometer test in order to quantify the infiltrated dye. Results were statistically evaluated by ANOVA and Tukey-Kramer test. No statistically significant differences were found among the adhesive systems when no etching agent was used. However, the Single Bond adhesive system showed statistically significant lower microleakage means than Clearfil Mega Bond and Prime & Bond 2.1 when 37% phosphoric acid was used. Single Bond and Clearfil Mega Bond adhesive systems presented similar behavior when the manufacturers' instructions were followed.     

Influence of time and thermocycling on marginal sealing of several dentin adhesive systems.

This study evaluated the in vitro microleakage of six dentin adhesive systems. Triangle-shaped Class V cavities with coronal margin in enamel and gingival margin in cementum or root dentin were cut in the buccal surfaces of 90 non-carious single-root human teeth. These teeth were randomly assigned into six groups (n = 15) for the evaluation of six different dentin adhesive systems: One Step, Prime & Bond 2.0, Syntac Single, Single Bond, Optibond Solo and Syntac Sprint. The preparations were restored with Degufill Ultra composite and polished using the Enhance system. Each group was randomly divided into three subgroups (n = 5): samples of the first subgroup were immersed in 2% methylene blue solution for seven days; those of the second subgroup remained in a similar solution for 31 days; those of the third subgroup were thermocycled 500x at 5-55 degrees C and immersed in 2% methylene blue for seven days. All 90 teeth were then embedded in methacrylate and bucco-lingually sectioned; the dye penetration was evaluated using an 0-4 ordinal scale. All of the dentin adhesive groups showed minimal leakage at the enamel margins with increased leakage at the gingival margins. Optibond Solo showed the best outcomes among the dentin adhesives tested.