Clinical guidelines for posterior restorations based on Coverage, Adhesion, Resistance, Esthetics, and Subgingival management. The CARES concept: Part I ­ partial adhesive restorations

Important changes have occurred over the last decades in the clinical application of the strategies for posterior restorations - from amalgam to composites in direct restorations and from traditional resistance form crowns to adhesive partial restorations such as onlays. Despite much evidence available for these advances, there are still very few established guidelines for common clinical questions: When does an indirect restoration present a clinical advantage over a direct one? When should one perform adhesive cusp coverage such as an onlay? When to implement resistance form designs in adhesive restorations? Which conditions create limitations for adhesion so that a resistance form preparation with a stiffer material such as a traditional crown might be more appropriate? In order to provide clinical guidelines, the present authors consider five parameters to support and clarify decisions - Coverage of cusps, Adhesion advantages and limitations, Resistance forms to be implemented, Esthetic concerns, and Subgingival management - the CARES concept. In Part I of this three-part review article, the focus is on clinical decisions for partial adhesive restorations regarding indications for direct versus indirect materials as well as the need for cusp coverage and/or resistance form preparations based on remaining tooth structure and esthetics.

To etch or not to etch, Part II: On the hydrophobic-rich content and fatigue strength of universal adhesives.

OBJECTIVE: To determine whether smear layer management, via conservative etching protocols, and the hydrophobic-rich content of hybrid layers would affect the fatigue strength of resin-dentin interfaces. METHODS: Bar-shaped dentin beams obtained from sound third molars were wet-polished for 30 s. Dentin was etched with 32 % ortho-phosphoric acid for 3 or 15 s, 10 % meta-phosphoric acid for 15 s or by a prime-and-rinse application using a mild universal adhesive (Scotchbond Universal, 3M ESPE). Self-etch application served as control. Coating was performed with a solvent-free bisGMA-based resin. Composite buildups were made with a nanofilled composite. Resin-dentin beams with twin-bonded interfaces were sectioned and stored in deionized water for 24 h at 37 â„ƒ before 4-point flexural quasi-static monotonic testing (n = 16). Stress-life fatigue behavior was evaluated under cyclic loading (n = 35) by the staircase method at 4 Hz. The tension side of cyclic-loaded unfractured beams were evaluated under SEM, along with the micro-morphology of etched dentin surfaces. Monotonic data was analyzed by two-way ANOVA followed by the Tukey Test and cyclic-loaded data by Kruskal-Wallis on Ranks (α = 0.05). RESULTS: Etching protocols and higher hydrophobic-rich content produced significantly higher fatigue life distributions (p < 0.05). Dentin demineralization was ranked as OPA 15 s > MPA 15 s > OPA 3 s > P + R > SE. Less aggressive etching and coating reduced crack formation at hybrid layers. SIGNIFICANCE: Current oversimplification trends in resin-dentin bonding constitute a trade-off between hybridization quality and easier adhesive handling. Controlled dentin etching and increasing the hydrophobic-rich content of hybrid layers may be necessary to extend the longevity of mild universal adhesives.

Influence of Smoking Habits on the Prevalence of Dental Caries: A Register-Based Cohort Study.

OBJECTIVE: This study aimed to evaluate the influence of smoking habit on the prevalence of dental caries lesions in a follow-up study. MATERIALS AND METHODS: A total of 3,675 patients (2,186 females and 1,489 males) with an average age of 51.4 years were included. Outcome measures were the incidence of dental caries defined as incipient noncavitated, microcavitated, or cavitated lesions which had been diagnosed through clinical observation with mouth mirror and probe examination evaluating change of texture, translucency, and color; radiographic examination through bitewing radiographs; or secondary caries through placement of a new restoration during the follow-up of the study. STATISTICAL ANALYSIS: Cumulative survival (time elapsed with absence of dental caries) was estimated through the Kaplan-Meier product limit estimator with comparison of survival curves (log-rank test). A multivariable Cox proportional hazards regression model was used to evaluate the effect of smoking on the incidence of dental caries lesions when controlled to age, gender, systemic status, frequency of dental hygiene appointments, and socioeconomic status. The significance level was set at 5%. RESULTS: Eight hundred sixty-three patients developed caries (23.5% incidence rate). The cumulative survival estimation was 81.8% and 48% survival rate for nonsmokers and smokers, respectively (p < 0.001), with an average of 13.5 months between the healthy and diseased state diagnosis. Smokers registered a hazard ratio for dental caries lesions of 1.32 (p = 0.001) when controlled for the other variables of interest. CONCLUSION: Within the limitations of this study, it was concluded that smoking habit might be a predictor for dental caries.

To etch or not to etch, Part I: On the fatigue strength and dentin bonding performance of universal adhesives.

OBJECTIVE: To characterize whether the bonding performance and fatigue strength of resin-dentin interfaces created by a universal adhesive would be affected by different H3PO4-application times to more accurately assess long-term durability. METHODS: Mid-coronal flat dentin surfaces with standardized smear-layers were produced on sound third molars, etched with 32% H3PO4 for 0, 3 and 15 s, bonded with a mild universal adhesive (3M-ESPE) and restored with a nanofilled composite. Bonded specimens (0.9 × 0.9 mm) were stored in deionized water for 24 h and sectioned into beams for microtensile testing (n = 10). Resin-dentin beams were tested under tension until failure (0.5 mm/min) after 24 h or 6 month storage in artificial saliva at 37 ̊C. Bar-shaped resin-dentin beams (0.9 × 0.9 × 12 mm) were tested under 4-point-flexure initially at quasi-static loads (n = 22) and then under cyclic loads (n > 50). The stress-life fatigue behavior was evaluated using the twin-bonded interface approach by the staircase method at 4 Hz. Fractured interfaces and the tension side of unfractured beams were evaluated under SEM, along with the micro-morphology of the etched dentin surfaces and hybrid layers. Data were analyzed by ANOVA and Tukey test and Wilcoxon Rank Sum Test (α = 0.05). RESULTS: Quasi-static loads were limited to discriminate the bonding performance of resin-dentin interfaces. Application modes significantly affected etching patterns, fatigue strength, endurance limits and hybrid layer morphology (p < 0.001). SIGNIFICANCE: Reductions in fatigue strength of self-etched bonded interfaces raise concerns about the true ability of universal adhesives to properly bond to dentin.

Risk Score to Predict Dental Caries in Adult Patients for Use in the Clinical Setting.

BACKGROUND: There is a need for risk prediction tools in caries research. This investigation aimed to estimate and evaluate a risk score for prediction of dental caries. MATERIALS AND METHODS: This case-cohort study included a random sample of 177 cases (with dental caries) and 220 controls (randomly sampled from the study population at baseline), followed for 3 years. The risk ratio (RR) for each potential predictor was estimated using a logistic regression model. The level of significance was 5%. RESULTS: The risk model for dental caries included the predictors: "presence of bacterial plaque/calculus" (RR = 4.1), "restorations with more than 5 years" (RR = 2.3), ">8 teeth restored" (RR = 2.0), "history/active periodontitis" (RR = 1.7) and "presence of systemic condition" (RR = 1.4). The risk model discrimination (95% confidence interval) was 0.78 (0.73; 0.82) (p < 0.001, C-statistic). Patients were distributed into three risk groups based on the pre-analysis risk (54%): low risk (

Long-term In Vitro Adhesion of Polyalkenoate-based Adhesives to Dentin.

PURPOSE: To study the influence of a polyalkenoate copolymer (VCP) on the immediate (24 h) and 6-month dentin bonding stability of VCP-based adhesives, using microtensile bond strength (µTBS), nanoleakage (NL), and ultramorphological analyses (FE-SEM). MATERIALS AND METHODS: Eighty-four caries-free molars were randomly assigned to seven adhesives: Clearfil SE Bond (CSE, Kuraray Noritake); Adper Single Bond Plus (SB, 3M ESPE); SB without VCP (SBnoVCP, 3M ESPE); Scotchbond Universal Adhesive applied as a etch-and-rinse adhesive (SBU_ER); SBU without VCP applied as an etch-and-rinse adhesive (SBUnoVCP_ER); SBU applied as a self-etch adhesive (SBU_SE, 3M ESPE); SBU without VCP applied as a self-etch adhesive (SBUnoVCP_SE, 3M ESPE). Half of the beams were tested after 24 h, and the other half was aged in water for 6 months prior to testing. For each tooth/evaluation time, two beams were randomly selected for NL analysis. Statistical analyses of µTBS results were performed using two-way ANOVA, Tukey's post-hoc tests, and Student's t-test for paired data (α = 0.05). Nanoleakage was statistically analyzed using the Kruskal-Wallis and Mann-Whitney tests, with Wilcoxon's test for paired data. For FE-SEM, four caries-free molars were assigned to each of the seven groups. Dentin disks were restored and cross sectioned into halves. One half was observed at 24 h, and the other at 6 months. RESULTS: The highest 6-month mean µTBS was obtained with SBU_SE/SBUnoVCP_SE and SBUnoVCP_ER. SBUnoVCP_SE resulted in greater silver deposition at 6 months. FE-SEM observations showed that CSE and SBU_SE specimens resulted in a submicron hybrid layer without signs of degradation at 6 months. CONCLUSIONS: VCP may contribute to the long-term bonding stability of VCP-based adhesives.

Chemical Adhesion of Polyalkenoate-based Adhesives to Hydroxyapatite.

PURPOSE: To evaluate the chemical interaction between synthetic hydroxyapatite (HAp) and polyalkenoic acid copolymer- based (also known as Vitrebond copolymer [VCP]) adhesives. MATERIALS AND METHODS: Six dentin adhesive formulations were used: 1) Adper Single Bond Plus (SB); 2) SB formulation without VCP (SBnoVCP); 3) Adper Easy Bond (EB); 4) EB formulation without VCP (EBnoVCP); 5) Scotchbond Universal adhesive (SBU); 6) SBU formulation without VCP (SBUnoVCP). Each adhesive was mixed with HAp, polymerized, and analyzed using FTIR and 13C/31P NMR spectroscopy. RESULTS: The FTIR spectra of SB+HAp indicated that the carbonyl group changed absorption wavenumber compared to that of SBnoVCP+HAp. 13C NMR analysis showed that the presence of methacrylated phosphoric esters in the EB and SBU formulations led to similar carbonyl resonance with or without VCP. 31P NMR revealed a resonance shift at 0.5 ppm for SB+HAp, EB+HAp and SBU+HAp spectra. In comparison with EB+HAp and SBU+HAp, a slight fade-out of the same resonance shift for EBnoVCP+HAp and SBUnoVCP+HAp was observed without completely disappearing, respectively, meaning that VCP might induce a modification of phosphorus moieties in addition to the ionic interaction between phosphate ester groups and HAp. CONCLUSION: Our data suggests that a chemical interaction occurred between VCP-containing adhesives and synthetic HAp.

Influence of a hydrophobic resin coating on the immediate and 6-month dentin bonding of three universal adhesives.

OBJECTIVE: To test the influence of a hydrophobic resin coating (HC) on the immediate (24h) and 6-month (6m) microtensile dentin bond strengths (µTBS) and nanoleakage (NL) of three universal adhesives applied in self-etch (SE) or in etch-and-rinse (ER) mode. METHODS: Sixty caries-free extracted third molars were assigned to 12 experimental groups resulting from the combination of the factors "adhesive system" (Scotchbond Universal Adhesive [SBU], 3M ESPE; All-Bond Universal [ABU], Bisco Inc.; and G-Bond Plus [GBP], GC Corporation); "adhesive strategy" (SE or ER); "hydrophobic resin coating" [HC] (with or without Heliobond, Ivoclar Vivadent); and "storage time" (24h or 6m). Specimens were prepared for µTBS testing - (24h) half of the beams were immediately tested under tension; and (6m) the other half was stored in distilled water (37°C) for 6m prior to testing. For each tooth, two beams were randomly selected for NL evaluation for both evaluation times. Data were analyzed for each adhesive system using three-way ANOVA and Tukey's post-hoc test (α=0.05). RESULTS: µTBS: (24h): In SE mode, HC resulted in statistically greater mean µTBS for all adhesives. (6m): When HC was not used the mean µTBS for SBU/ER, ABU/ER, GBP/ER and SBU/SE decreased significantly. NL: (24h): SBU/ER, ABU/ER and GBP/SE resulted in a significant reduction in NL when HC was applied. (6m): No significant reduction was observed for SBU/ER or for SBU/SE regardless of the use of HC. SIGNIFICANCE: The application of a hydrophobic resin coating improved the 24h and the 6m performances of all three adhesives systems in SE mode.

Effects of solvent evaporation time on immediate adhesive properties of universal adhesives to dentin.

OBJECTIVE: To evaluate the microtensile bond strengths (µTBS) and nanoleakage (NL) of three universal or multi-mode adhesives, applied with increasing solvent evaporation times. METHODS: One-hundred and forty caries-free extracted third molars were divided into 20 groups for bond strength testing, according to three factors: (1) Adhesive - All-Bond Universal (ABU, Bisco, Inc.), Prime&Bond Elect (PBE, Dentsply), and Scotchbond Universal Adhesive (SBU, 3M ESPE); (2) Bonding strategy - self-etch (SE) or etch-and-rinse (ER); and (3) Adhesive solvent evaporation time - 5s, 15s, and 25s. Two extra groups were prepared with ABU because the respective manufacturer recommends a solvent evaporation time of 10s. After restorations were constructed, specimens were stored in water (37°C/24h). Resin-dentin beams (0.8mm(2)) were tested at 0.5mm/min (µTBS). For NL, forty extracted molars were randomly assigned to each of the 20 groups. Dentin disks were restored, immersed in ammoniacal silver nitrate, sectioned and processed for evaluation under a FESEM in backscattered mode. Data from µTBS were analyzed using two-way ANOVA (adhesive vs. drying time) for each strategy, and Tukey's test (α=0.05). NL data were computed with non-parametric tests (Kruskal-Wallis and Mann-Whitney tests, α=0.05). RESULTS: Increasing solvent evaporation time from 5s to 25s resulted in statistically higher mean µTBS for all adhesives when used in ER mode. Regarding NL, ER resulted in greater NL than SE for each of the evaporation times regardless of the adhesive used. A solvent evaporation time of 25s resulted in the lowest NL for SBU-ER. SIGNIFICANCE: Residual water and/or solvent may compromise the performance of universal adhesives, which may be improved with extended evaporation times.

Influence of a hydrophobic resin coating on the bonding efficacy of three universal adhesives.

OBJECTIVES: To evaluate the effect of an additional hydrophobic resin coating (HE) on the resin-dentine microtensile bond strengths (µTBS), nanoleakage (NL), and in situ degree of conversion (DC) of three universal adhesives used in the etch-and-rinse (ER) and the self-etch (SE) modes. METHODS: Sixty caries-free extracted third molars were divided into 12 groups according to the combination of the factors adhesive (All-Bond Universal [ABU]; G-Bond Plus [GBP] and Scotchbond Universal [SBU]), adhesive strategy (ER and SE), and the use of HE (Heliobond; yes or no). After restorations were constructed, specimens were stored in water (37°C/24h) and sectioned into resin-dentine beams (0.8mm(2)) to be tested under tension (0.5mm/min). Selected beams from each tooth were used for DC quantification and for NL evaluation. Data from each adhesive were analyzed with two-way ANOVA and Tukey's test (α=0.05). RESULTS: ABU and GBP resulted in higher µTBS in the ER mode. The use of HE increased the µTBS of ABU and GBP only in the SE mode. Lower NL was observed for SBU and ABU in the ER mode+HE, and for GBP in the SE mode+HE. SBU and GBP showed higher DC when used in the ER mode, which was increased with HE application. The DC of ABU was similar in all conditions. CONCLUSIONS: The conversion of 1-step SE to 2-step SE may increase the µTBS and DC of current universal adhesives. The reduction in the NL is more dependent on the adhesive composition than on the bonding strategy.

Prefabricated veneers - bond strengths and ultramorphological analyses.

PURPOSE: To measure the microshear bond strengths (µSBS) of composite resin to the intaglio surface of prefabricated indirect veneers and analyze the FE-SEM ultramorphology of the pretreated intaglio surfaces as well as the fracture modes. MATERIALS AND METHODS: Three veneer systems (veneer and respective luting material) were used in this study: two prefabricated veneer types, Cerinate One-hour (CER, DenMat) and Componeer (CMP, Coltene), and a laboratory- made veneer, IPS e.max Press (IPS, Ivoclar Vivadent) used as the control. For each group, 10 veneers were used. After delimitation of the bonding area with a double-faced adhesive tape, 0.8-mm-diameter cylinders of composite luting material were bonded to the pretreated intaglio surface. After polymerization, the specimens were fractured in shear mode using the wire-loop method in a universal testing machine. The pretreated intaglio surface of two extra veneers and four fractured specimens per group were morphologically characterized using FE-SEM. RESULTS: CER resulted in statistically lower mean µSBS (7.1 ± 1.2 MPa) than the other two veneer systems, CMP (15.2 ± 2.5 MPa) and IPS (14.7 ± 1.7 MPa) at p < 0.0001. As seen with the FE-SEM, the intaglio surface of CMP did not display microretentive features, while multiple microretentions were observed in both CER and IPS after HF etching. CONCLUSION: Within the limitations of this in vitro study, the CMP and IPS veneer systems resulted in greater bond strengths than those of the CER veneer system.

Effects of industrial noise on circumpulpar dentin--a field emission scanning electron microscopy and energy dispersive spectroscopy analysis.

Chronic exposure to Industrial Noise (IN), rich in Low Frequency Noise (LFN), causes systemic fibrotic transformation and sustained stress. Dental wear, significantly increased with exposure to LFN, affects the teeth particularly through the circumpulpar dentin. Our goal is to understand the consequences of IN exposure on the circumpulpar dentin of Wistar rats. 10 Wistar rats were exposed to IN for 4 months, according to an occupationally simulated time schedule and 10 animals were used as age-matched controls. The first and the second upper and lower molars of each animal were processed for observation by Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS) analysis was performed. In exposed animals FESEM showed a 2.0 to 6.0 µm-dense mineral band between dentin and the pulp with no regular continuity with the tubules. This structure had a few tubules where the odontoblasts processes could be observed embedded within the band and collagen fibers were trapped inside. EDS analysis revealed that it was hydroxyapatite similar to dentin, with a higher carbon content. FESEM results show that the band may be tertiary reparative dentin formed by odontoblast-like cells, but the increased amount of carbon (EDS) could mean that it is sclerotic dentin. IN should be acknowledge as a strong stimulus, able to cause an injury to odontoblasts and to the formation of reparative tertiary dentin, in a process that may accelerate the aging of the teeth, either by direct impact of acoustic pressure pulsations or by increased stress and dental wear.

Effect of substrate age and adhesive composition on dentin bonding.

PURPOSE: To study the effect of dentin age and adhesive composition on the microtensile dentin bond strengths (µTBS) of five dentin adhesives. MATERIALS AND METHODS: Sixty extracted caries-free human teeth were assigned to the appropriate age group: less than 21 years of age (<21), 21-40 years of age (21-40), and greater than 40 years of age (>40). For each age group, specimens were randomly divided into five dentin adhesives: (1) Adper Easy Bond (EB, 3M ESPE), a one-step self-etch adhesive; (2) Experimental Adper Easy Bond without the Vitrebond Co-polymer (CP) (EBnoCP, 3M ESPE); (3) Adper Single Bond Plus (SB, 3M ESPE), a two-step etch&rinse adhesive; (4) Experimental Adper Single Bond Plus without CP (SBnoCP, 3M ESPE); and (5) Adper Scotchbond Multi-Purpose (MP, 3M ESPE), a three-step etch&rinse adhesive, as the control group. Specimens were sectioned in X and Y directions and the resulting beams were tested to failure in tension mode at a crosshead speed of 1 mm/min. Statistical analysis was computed using t-test and two-way analysis of variance followed by Fisher least significant difference multiple comparison post hoc test at p < 0.05. RESULTS: The highest mean µTBS values were obtained in the control group (MP) for all age groups. EB resulted in statistically similar mean µTBS compared to EBnoCP for all age groups: p = 0.538 for (<21); p = 0.974 for (21-40); and p = 0.909 for (>40). SB resulted in statistically higher mean µTBS than SBnoCP for all age groups [p<0.009 for (<21); p<0.028 for (21-40); and p<0.041 for (>40)]. MP, the control group, resulted in statistically lower mean µTBS when applied to the oldest age group (>40) compared to the youngest age group (<21), at p < 0.04. When means were pooled for the variable 'age group,' SB resulted in significantly higher mean µTBS than SBnoCP at p < 0.009, while EB resulted in statistically similar mean µTBS compared to EBnoCP (p=0.9). MP resulted in statistically higher mean µTBS than all other adhesives-SB (p<0.0001), SBnoCP (p<0.0001), EBnoCP (p<0.022), and EB (p<0.046). CONCLUSIONS: The substrate age influenced the bonding ability of the three-step etch&rinse adhesive. The presence of a carboxylic-based polymer (CP) enhanced the bonding ability of the two-step etch&rinse adhesive.

Dentin bond strengths of four adhesion strategies after thermal fatigue and 6-month water storage.

STATEMENT OF PROBLEM: The stability of current dental adhesives after artificial aging may depend on the adhesion strategy. PURPOSE: To evaluate the effect of thermal fatigue and water storage on the dentin microtensile bond strengths (µTBS) of four adhesion strategies. MATERIALS AND METHODS: Forty-eight human molars were assigned to four dentin adhesives: FL--OptiBond FL (Kerr Corporation, Orange, CA, USA); SOLO--OptiBond SOLO Plus (Kerr Corporation); XTR--OptiBond XTR (Kerr Corporation); and AIO--OptiBond All-in-One (Kerr Corporation). Teeth were restored with a hybrid composite, and sectioned to obtained bonded beams. For each adhesive, one-third of the central and peripheral beams were assigned to one of three aging conditions: (1) kept in distilled water for 24 hours (24 h); (2) thermocycled (TC) for 20,000 cycles; and (3) stored in distilled water for 6 months (6M). Beams were tested in tension mode. Statistical analysis (p < 0.05) was computed using Analysis of Variance and Fisher's Least Significant Difference post hoc test. RESULTS: The highest mean µTBS for 24 h, TC, and 6M were obtained with XTR, but only the 6M mean µTBS were significantly higher than those of the other three adhesives. For FL, mean µTBS decreased significantly from 24 h to TC. For SOLO, mean µTBS remained stable over the three aging conditions. Mean µTBS for AIO decreased significantly from 24 h to 6M. CONCLUSION: The self-etch adhesives XTR and AIO performed similarly or better than the etch-and-rinse adhesives FL and SOLO for all three testing conditions. Their aging stability seems to be material-dependent.

Laboratory bonding ability of a multi-purpose dentin adhesive.

PURPOSE: To evaluate the laboratory dentin and enamel microtensile bond strengths (microTBS) and interfacial ultra-morphology of a new multi-purpose dental adhesive applied under different bonding strategies. METHODS: microTBS - 36 extracted caries-free human molars were assigned to six groups: Group CSE - Clearfil SE Bond, a 2-step self-etch adhesive (self-etch control); Group SBU-SE - Scotchbond Universal Adhesive (SBU), applied as a one-step self-etch adhesive; Group OSLm - OptiBond SOLO Plus (OSL), a 2-step etch-and-rinse adhesive applied on moist dentin (etch-and-rinse control); Group OSLd - OSL applied on air-dried dentin; Group SBU-ERm - SBU applied as a 2-step etch-and-rinse adhesive on moist dentin; Group SBU-ERd - SBU applied as a 2-step etch-and-rinse adhesive on air-dried dentin. Build-ups were constructed with Filtek Z250 and cured in three increments of 2 mm each. Specimens were sectioned with a slow-speed diamond saw under water in X and Y directions to obtain bonded beams that were tested to failure in tension at a crosshead speed of 1 mm/minute. Statistical analyses were computed using one-way ANOVA followed by post-hoc tests at P< 0.05. Ultra-morphologic evaluation - dentin-resin interfaces were prepared for each of the six groups, processed, and observed under a FESEM. RESULTS: microTBS - OSLm resulted in significantly higher mean microTBS (63.0 MPa) than the other five groups. All SBU groups ranked in the same statistical subset regardless of the dentin treatment. The lowest mean microTBS were obtained with CSE (47.2 MPa) and OSLd (50.2 MPa), which were ranked in the same statistical subset. Ultramorphologic evaluation - The two self-etch adhesives resulted in a similar ultra-morphology. Dried dentin did not preclude the formation of a hybrid layer with SBU-ERd, as opposed to OSLd.

Microtensile bond strengths and interfacial examination of a polyalkenoate-based 1-step adhesive.

PURPOSE: To study the effect of acid etching and the application of a hydrophobic bonding resin on the microtensile bond strengths (microTBS) and marginal sealing of the 1-step self-etch adhesive Adper Easy Bond (AEB). METHODS: Middle dentin was exposed in 30 extracted molars and randomly divided into six groups: (1) AEB applied as per manufacturer's directions; (2) as in AEB, but one coat of hydrophobic resin (HR) was applied and cured over AEB (AEB+HR); (3) etching with 35% H3PO4 for 15 seconds followed by AEB (Etch+AEB); (4) as in group Etch+AEB, but one coat of HR was applied and cured over AEB (Etch+AEB+HR); (5) Adper Single Bond Plus, the 2-step etch-&-rinse adhesive control (ASB); (6) Adper Scotchbond Multi-Purpose, the 3-step etch-&-rinse adhesive control (SBMP). Buildups were constructed with Filtek Z250 and cured in three increments of 2 mm each. Specimens were sectioned with a slow-speed diamond saw under water in X and Y directions to obtain bonded sticks with a cross section of 0.8 +/- 0.2 mm2 and tested to failure in tension mode at a crosshead speed of 1 mm/minute. Statistical analyses were computed using one-way ANOVA followed by Duncan's post-hoc test at P<0.05. For marginal sealing, 36 Class V preparations were restored with one of the six adhesive combinations and processed with 50% ammoniacal silver nitrate. After sectioning, specimens were observed under a backscattered FE-SEM to evaluate silver infiltration into the resin-dentin interface, which was measured in ranks (0-4) and compared with non-parametric statistical tests (P<0.05). RESULTS: AEB resulted in statistically lower mean microTBS than all other groups at P0.05. All the remaining groups resulted in statistically similar mean microTBS. For marginal sealing, data were grouped in three statistical subsets: Groups AEB and AEB+HR resulted in statistically less silver infiltration than groups Etch+AEB and Etch+AEB+HR. Groups ASB and SBMP resulted in similar silver infiltration compared to Groups AEB and AEB+HR. The nanoleakage pattern consisted of agglomerates of silver deposits located predominantly in the hybrid layer, while reticular or water-tree silver deposits were observed in both the AEB and ASB adhesive layers.

Bonding ability of three ethanol-based adhesives after thermal fatigue.

PURPOSE: To study the effect of thermal fatigue on the microTBS and interfacial morphology of three ethanol-based etch-&-rinse 2-bottle adhesives. METHODS: microTBS - 24 third molars were randomly assigned to one of three adhesive systems: (1) Adper Single Bond Plus (SBP, 3M ESPE); (2) Ambar (AMB, FGM); (3) Excite (EXC, Ivoclar Vivadent), and restored with a hybrid resin composite. For each adhesive, half of the specimens were thermocycled (TC) for 20,000 cycles (5-55 degrees C) while the other half was kept in distilled water for 24 hours at 37 degreesC (control). Specimens were sectioned in X and Y directions and the resulting sticks were tested to failure in tension mode at a crosshead speed of 1 mm/minute. Statistical analysis was computed using ANOVA and Tukey's post hoc for the microTBS; and non-parametric cross-tabulation with Chi-Square for the pre-testing failures at P< 0.05. Interfacial morphology -The occlusal enamel was removed from 12 extracted molars perpendicular to the long axis of the tooth. Teeth were equally assigned to one of the three adhesives and restored with a 1 mm-thick layer of a hybrid composite resin. A 2 mm-thick disk was sectioned from each specimen and cross-sectioned in two identical halves. Half of the each specimen was TC for 20,000 cycles (5-55 degrees C) while the other half was kept in distilled water for 24 hours at 37 degrees C (control). Specimens were chemically challenged and prepared for FESEM observation to observe the integrity of the hybrid layer before and after thermal fatigue. Micrographs were recorded digitally at standard magnifications and measurements were taken with the microscope embedded image software. RESULTS: microTBS - SBP and AMB resulted in statistically similar mean microTBS regardless of thermal fatigue. EXC resulted in statistically lower mean microTBS than SBP and AMB for the control (P< 0.001) and for the TC specimens (P< 0.0001). Interfacial morphology - The hybrid layers of SBP and AMB were densely infiltrated without interfacial failure. For EXC, extensive areas of debonding were observed between the adhesive layer and the hybrid layer both for the control and the TC groups. Thermal fatigue did not influence the bonding ability of AMB and SBP, but was detrimental for EXC.

In vitro sealing potential of a self-adhesive pit and fissure sealant.

OBJECTIVE: To study the sealing ability of a self-adhesive sealant. METHOD AND MATERIALS: Thirty-five extracted molars were assigned to seven groups: group 1, 35% phosphoric acid (PA) followed by Clinpro Sealant (CL) as the control group; group 2, Enamel Loc (EL), a self-adhesive sealant; group 3, PA followed by EL; group 4, Adper Prompt L-Pop (AP) followed by CL; group 5, AP followed by EL; group 6, PA followed by Adper Single Bond Plus (SB) and CL; and group 7, PA followed by SB and EL. Specimens were thermocycled and immersed in 50 wt% ammoniac silver nitrate. Silver leakage was measured in ranks from 0 to 4 and analyzed with Kruskal-Wallis and Mann-Whitney tests at P < .05. One additional tooth per group was used to study the enamel etching pattern. Specimens were observed under a field-emission SEM. RESULTS: The least silver infiltration was measured for group 1 (control group), which was significantly different from all other six groups. Etching enamel prior to the application of EL resulted in significantly less leakage than all other groups, except for the control group. EL alone resulted in similar leakage to EL with either AP or SB. None of the groups resulted in perfectly sealed interfaces. Under SEM, EL was unable to etch enamel. The self-etch adhesive AP resulted in a less defined etching pattern than the etch-and-rinse adhesive SB. CONCLUSION: Etching enamel with phosphoric acid is still essential for sealing the enamel-sealant interface. The self-adhesive sealant tested in this study may not be indicated for clinical use.