Influence of storage time on bond strength of self-etching adhesive systems to artificially demineralized dentin after a papain gel chemical–mechanical agent application

ObjectivesThe aim of this study was to evaluate the influence of storage time on the bond strength of self-etching adhesive systems to artificially demineralized dentin submitted to application of a papain-based chemical mechanical agent for carious tissue removal.Materials and MethodsTwenty-four blocks of human coronal dentin were randomly divided into 2 groups: (1) restored with a two-step self-etching adhesive system (Clearfil SE Bond); (2) restored with a one-step self-etching adhesive system (One-Up Bond F Plus). After artificial caries induction, the specimens were treated with papain-based gel, received an application of the adhesive system according to the respective group, and blocks of microhybrid resin composite measuring 5.0 mm high and 5.0 mm wide were fabricated incrementally on the tooth, which would later be cut to obtain sticks with a bond area of around 1 mm², for use in the microtensile tests. After this, half of the sticks obtained from each tooth were submitted to the microtensile test 24 h later, while the other half were stored in water, in an oven at 37° C for a period of 180 d. The specimens were submitted to the microtensile test in a Universal Test Machine at a speed of 0.5 mm/min. The surfaces of the fractured test specimens were examined visually under a stereoscopic loupe in order to classify the fracture type. After exploratory analysis of the data, the two-way Analysis of Variance (ANOVA) and the Tukey test were applied. The data on the fracture types were analyzed by the Exact Fisher test.ResultsNo statistically relevant differences were verified among the means of the microtensile bond strength values of the adhesive systems evaluated in the different storage times. Mixed and adhesive fractures types were observed for both groups.ConclusionStorage time did not influence the bond strength of the two-step or one-step self-etching adhesive systems to artificially demineralized dentin submitted to application of a papain-based chemical mechanical agent for carious tissue removal. Both adhesive systems provided similar bond strength at different storage times.     

Polymerization and adhesion behavior of experimental dental bonding materials with different initiator systems

The use of alternative photoinitiators has been reported as a way to improve physical-mechanical characteristics of dental adhesive systems. In this way, the aim of this study was to evaluate the degree of conversion (DC) and dentin bond strength in dentin cavities of experimental simplified adhesive systems formulated with alternative photoinitiators and diphenyliodonium hexafluorophosphate (DPIHFP). A model simplified adhesive system was formulated by mixing a similar blend of monomers with different photoinitiator systems: camphorquinone (CQ), phenylpropanedione (PPD), bis-alkyl phosphine oxide (BAPO), CQ/PPD, and CQ/BAPO; with or without the addition of DPIHFP. DC was measured using Fourier Transform Infrared Spectroscopy. Bond strength was evaluated in bovine dentin cavities. DPIHFP increased DC for the CQ-based system, but did not affect the dentin bond strength. The PPD system showed the highest DC. All photoinitiator systems provided similar dentin bond strength. DPIHFP seems to increase the DC of CQ-based system, but it had no influence on PPD or BAPO systems. PPD was the most effective for to increase DC without improving bond strength of adhesive systems. Therefore, it is recommended that new adhesive systems to be formulated with phenylpropanedione to increase the DC of tooth restorations caused by traditional camphorquinone-based adhesive systems.     

Effect of 2% chlorhexidine digluconate application and water storage on the bond strength to superficial and deep dentin

The aim of the present in vitro study was to evaluate the effect of chlorhexidine, applied before a self-etching adhesive system (Clearfil SE Bond) on microtensile bond strength to superficial and deep dentin (DD), immediately and after six months of water storage (WS). Forty dentin specimens were divided into two groups according to dentin depth: superficial and deep. The specimens were then divided according to the solution to be applied (n = 10): CLX: 2% chlorhexidine (passively applied for 60 s) and NT (no treatment). A self-etching adhesive system was applied according to the manufactures instructions, with composite restorative placed on the dentin surface. After 24 h, dentin–resin blocks were sectioned into beam-shaped specimens that were submitted to microtensile bond strength testing either immediately or after six months of WS. Data were submitted to three-way ANOVA (α = 0.05). Bond strength values for the deep dentin group were significantly lower than those observed for superficial dentin (SD) (p = 0.002), whether chlorhexidine solution had been applied or not. There was no statistical difference in bond strength for specimens tested after 24 h and 6 months of WS. The application of chlorhexidine did not affect immediate and long-term bond strength to dentin. Bond strength in deep dentin was lower than in SD.     

Assessment of the initial and aged dentin bond strength of universal adhesives

This study evaluated the effect of mechanical loading on microtensile bond strengths (μTBS) of universal adhesives to dentin and quantified adhesive dentin penetration using micro-Raman spectroscopy. Human molars had occlusal dentin exposed and were allocated into eight groups: All-Bond Universal and Scotchbond Universal using etch-and-rinse and self-etch approaches, Adper Prompt L-Pop, Adper Single Bond Plus, Clearfil SE Bond, and Optibond FL. Following bonding procedures and build-ups, specimens were either stored in water at 37 °C for 24 h or mechanically loaded (50,000 cycles, 50 N) prior to μTBS test. Additional teeth were prepared for micro-Raman analysis of adhesive penetration and FE-SEM. Data were analyzed by two-way ANOVA and Tukey׳s post hoc test (P<0.05). Mechanical loading had no deleterious effect on μTBS with the exception of Adper Prompt L-Pop. Incomplete infiltration of the demineralized dentin was noticed for adhesives using the etch-and-rinse approach and for Scotchbond Universal in the self-etch approach.     

Biodegradation of caries-affected dentin bonding interface of fluoride and MDPB-containing adhesive system

The aim of this study was to evaluate the effect of a fluoride/MDPB (12-methacryloyloxydodecylpyridinium bromide)-containing adhesive system on the durability of a bond to permanent artificially induced caries-affected dentin (CAD) exposed to Streptococcus mutans culture and water storage. Twelve third molars were selected. Flat dentin surfaces were submitted to artificial caries development in S. mutans and Broth heart infusion (BHI). Caries-infected dentin was removed with burs according to clinical criteria and CAD cavities were restored with Adper Scotchbond Multi-Purpose (SBM) and Clearfil Protect Bond (CPB). Nontrimmed resin–dentin bonded interfaces (1 mm²) were stored in S. mutans+BHI for 3 days, in deionized water for 3 months, and afterwards subjected to microtensile bond strength test (μTBS). The control group was not submitted to storage and immediate μTBS testing was performed. Fractographic analysis was performed after μTBS testing. Four molars were restored as described, and morphological evaluation hybrid layer (HL) was performed by scanning electron microscopy (SEM). Two-way ANOVA with split-plot design and Tukey′s tests were performed. No difference was found between μTBS values of SBM and CPB irrespective of groups. Significant decrease was observed in μTBS values after S. mutans culture and water storage, but without difference between them. CPB had more homogenous hybrid layer than SBM. Fluoride/MDPB-containing adhesive system did not prevent degradation of CAD bond strength in both degradation methods.     

Effect of proanthocyanidin incorporation into dental adhesive on durability of resin–dentin bond

BackgroundProanthocyanidin has shown to have beneficial effects on dentin bonding via its collagen cross-linking and protease inhibitory effects.ObjectiveThis study evaluated the effect of incorporation of 1–3% PA into a dental adhesive on durability of resin–dentin bond.Materials and methodsThe experimental adhesive was first formulated by combining 50 wt% comonomer mixtures with 50 wt% ethanol. PA was then added to the ethanol-solvated adhesive to yield three groups of adhesives at concentrations of 1.0 wt%, 2.0 wt% and 3.0 wt%. The PA-free adhesive served as control. Flat dentin surfaces from forty extracted third molars were etched with 32% phosphoric acid and the specimens were randomly assigned to one of the four adhesive groups. Two layers of experimental adhesives were applied to etched dentin and light-cured for 20 s after solvent evaporation. Composite build-ups were performed using Filtek Z250 (3M ESPE). The bonded teeth were divided into three subgroups for different methods of storage: (1) 24 h indirect water exposure (IE), (2) 6 M IE and (3) 6 M direct water exposure (DE). After the designated period of water storage, the bonded teeth were sectioned into 0.9 mm×0.9 mm beams for bond strength testing. Bond strength data were evaluated by two-way ANOVA and Tukey׳s tests (α=0.05). Interfacial nanoleakage was examined using a field-emission scanning electron microscopy. Two-way ANOVA and Tukey׳s tests were used to examine the effects of PA concentration and water exposure on bond strength and percentage of nanoleakage (α=0.05).ResultsTwo-way ANOVA showed that the factors, water exposure and PA concentration had a significant effect on bond strength (p<0.001). Interaction between the two factors was also significant (p<0.001). Bond strength of all four adhesives decreased with PA concentrations and ageing. Type of water exposure had no effect on the bond strength of PA-incorporated adhesive; while direct water exposure significantly reduced the bond strength of PA-free adhesive. Conversely, the factors, water exposure and PA concentration showed a significant effect on nanoleakage percentage (p<0.001). Interaction between the two factors was not significant (p>0.05).ConclusionIncorporation of proanthocyanidin into a dental adhesive did not prevent resin–dentin bond degradation over time.     

Development of a simplified etch-and-rinse adhesive containing niobiophosphate bioactive glass

PurposeThe aim of this study was to evaluate radiopacity, degree of conversion (DC), Knoop hardness (KHN), ultimate tensile strength (UTS) and microtensile bond strength (µTBS) to dentin of an experimental adhesive containing micro-filler of niobium–phosphate bioactive glass (NPG).Materials and methodsThe NPG glass was produced by fusion of NbO₅, Na₂CO₃, CaO, (NH₄)₂HPO₄ at 1400 °C. After cooling, the glass was ground to a mean particle size<25 µm, and either added (40 wt%) to an experimental adhesive resin mix containing monomers and solvent, or not. The DC of the adhesives was evaluated by Fourier transform infrared spectroscopy. Flat dentin surfaces were obtained from 16 molar teeth, and prepared for use to evaluate µTBS (n=8). An hourglass-shaped matrix (UTS and KHN) or disk-shaped matrix (radiopacity) was filled with adhesive and light-polymerized. The data from each test were analyzed by appropriate statistical methods.ResultsThe presence of glass particles made the adhesive system radiopaque. Addition of bioactive NPG glass particles to the adhesive system prevented decreases in bond strength; reduced the UTS and increased DC and KHN. All groups showed predominance of adhesive failure mode.ConclusionAddition of 40% NPG glass may be an alternative to obtain an adhesive system with adequate mechanical and bond strength to dentin properties.     

Bond strength and adhesive interface analysis using EDTA as a dentin conditioner

This study evaluated dentin bond strength and dentin-resin interfacial morphology using phosphoric acid-etching and EDTA-conditioning. The occlusal enamel of twenty-four human third molars was removed to expose the dentin surfaces, which were polished with a SiC paper (600 grit). Teeth were randomly divided into three groups (n = 8): etching with 37% phosphoric acid (15 s), conditioning with 0.1 M EDTA (60 s) and 0.5 M EDTA (120 s). Adhesive (XP Bond, Dentsply) was applied and three layers (2 mm each) of composite (EsthetX, Dentsply) were placed and light-activated separately (20 s). Teeth were sectioned to obtain specimens for the microtensile bond strength test (1 mm² at cross section). Half of the specimens was tested in a universal testing machine (EZ Test, Shimadzu) after 24 h and the other half after storage for 10 months. Failure mode and adhesive interface were analyzed using scanning electron microscopy. Data were analyzed by mixed models for repeated measures (PROC MIXED) and Tukey-Kramer test, considering a significance level of 5%. Mean bond strength values (SD) after 24 h and 10 months were, respectively (in MPa): phosphoric acid: 37.3 (7.7) / 33.9 (6.7); 0.1 M EDTA: 14.7 (7.3) / 15.1 (10.1); 0.5 M EDTA: 25.1 (7.7) / 21.1 (14.1). Dentin treatment with EDTA and phosphoric acid resulted in hybrid layer and resin tags formation. Mixed failures were prevalent for all groups tested after 24 h. Storage for 10 months changed the failure mode for the 0.5 M EDTA group to adhesive failure (between dentin and bonding agent). EDTA applied for 60 s yielded lower bond strength results compared to phosphoric acid and EDTA (120 s), but there was no significant reduction after 10 months of storage for any of the tested groups.     

Effect of epigallocatechin gallate,green tea extract and chlorhexidine application on long-term bond strength of self-etch adhesive to dentin

This study evaluated the effect of dentin pretreatment with metalloproteinase inhibitors on long-term microtensile bond strength (μTBS) of self-etch adhesive (SEA) to dentin. Thirty-two dentin fragments received pretreatments (n=8): C: control (not treated); GT: 2% green tea extract; CLX: 2% chlorhexidine; EGCG: 2% epigallocatechin gallate. SEAs (Clearfil SE Bond) and resin composite were applied to dentin surface. After 24 h, resin-blocks were cut into sticks submitted to μTBS testing immediately or after 6 months of storage in water. Two-way ANOVA and Tukey test (α=5%) indicated that CLX group showed μTBS values statistically superior to the other groups at immediate testing, whereas those of EGCG group were the lowest (p=0.018). After 6 months, a significant increase in μTBS values was observed for all groups, except for CLX (p=0.018). In conclusion, μTBS increased in dentin pretreatment with EGCG and green tea groups, and in the non-treated group.     

Microtensile versus microshear bond strength between dental adhesives and the dentin substrate

This study evaluated the performance of different bonding tests on the bond strength of three adhesive systems to dentin. Forty-eight bovine incisors were used in the study, which were allocated in two groups according to the bond strength test performed: microtensile (µTBS) or microshear (µSBS). Also, each group was divided in three subgroups according to the adhesive system applied: Single Bond (SB), Prime & Bond (PB) and XP Bond (XPB) (n=8). The teeth were prepared according to each bond strength test protocol, and then the specimens were tested in an universal testing machine (EMIC). The data were submitted to two-way ANOVA (bond strength test and adhesive system type factors) and Tukey's post hoc test (α=0.05). The µTBS results were higher for all the adhesives when compared to the µSBS ones. Within the µTBS results, SB showed higher bond strength than PB and XPB, which showed similar adhesive performance among each other; within the µSBS results, all the adhesives presented similar bond strength values to dentin. The µTBS test detected differences between the adhesive systems evaluated; in contrast, the µSBS test was less discriminating in evaluating the adhesive performance of the materials tested.     

Effect of erosive challenge and Nd:YAG laser irradiation on bond strength of adhesive systems to dentin

PurposeTo evaluate the effect of Nd:YAG laser irradiation and erosive challenge on bond strength of two adhesive systems to dentin.MethodsTwenty bovine incisors were cut and grounded to obtain eighty slabs of flat dentin. Specimens were allocated into eight groups, based on: adhesive system—a two-step etch-and-rinse and a two-step self-etch; laser irradiation—Nd:YAG (1 W/10 Hz) or control (no laser irradiation); and erosive challenge after restorative procedure—presence or absence of erosive challenge. Nd:YAG laser groups were submitted to laser irradiation before the restorative procedure. Blocks of composite resin were built up on the bonded surfaces with a Southern Dental Industries device to perform shear bond strength (SBS) test. After, each specimen of erosive challenge, groups were subjected to immersion in Sprite Zero^® (20 ml/2 h/24 °C/under agitation). The SBS test (0.5 mm/min) was performed after 24 h of water storage at 37 °C. Failure mode was evaluated with a stereomicroscope (X400). Data were analyzed with three-way ANOVA and Tukey’s post hoc tests (α=0.05).ResultsThe etch-and-rinse adhesive system presented higher bond strength values than self-etch adhesive. Laser irradiation increased the bond strengths values when erosive challenge was present. The predominant failure mode observed was adhesive.ConclusionsThe irradiation of Nd:YAG laser positively influences the bond strength values when erosive challenges are present. Moreover, the etch-and-rinse adhesive system is a better option to be used in dentin in this clinical condition.     

Deproteinization stabilises dentin bonding of self-adhesive resin cements after thermocycling

This study examined the effect of deproteinization on the microtensile dentin bond strength (µTBS) and nanoleakage (NL) of conventional and self-adhesive resin cements after 24 h or after 20,000 thermocycles. Occlusal dentin of thirty-two human molars were distributed into four groups according to the type of cement used: conventional or self-adhesive; and the strategy of luting: RelyX ARC/Single Bond 2 (RAc) following the manufacturer׳s instructions (control), RelyX ARC/Single Bond 2 (RAd) applied after dentin deproteinization; RelyX U200 (RUc) following the manufacturer´s instructions (control); RelyX U200 (RUd) applied after dentin deproteinization. The specimens were cut into non-trimmed dentin–composite sticks and the half sticks of each group were subdivided into two subgroups: 24 h water storage and after 20,000 thermal cycles, before microtensile bond test. For NL, 5 bonded sticks from each subgroup were prepared and analyzed under SEM. Three-way ANOVA showed that the dentin deproteinization increased the µTBS of both cements, although the RAd group showed a decrease on the µTBS after thermocycling. Chi-square test showed significant loss of specimens by premature failure for the groups after thermocycling, except for the RUd group. The dentin deproteinization improved the initial µTBS and decreases the NL of both cements tested, but, after thermocycling, this technique is only effective for RelyX U200.     

Influence of dentin biomodification with epigallocatechin-3-gallate on the bond strength of self-etch adhesive: Twelve-month results

To evaluate the effectiveness of dentin biomodification with epigallocatechin-3-gallate (EGCG) on the resin-dentin bonds over time. Twenty seven extracted human third molars were prepared to expose a flat dentin surface and divided into 3 groups (n=9). Dentin surfaces were dried and treated with 20 µL aliquots of either distilled water (control); 2% chlorhexidine digluconate solution (CHX) or 0.1% EGCG aqueous solution. Solutions were rubbed for 60 s followed by bonding with Adper Easy One, and 5-mm-thick resin crown build-up. Bonded teeth were stored in distilled water for 24 h and then longitudinally sectioned to obtain bonded sticks. One-third of the specimens were immediately subjected to a microtensile bond strength test in tension at 0.5 mm/min, while the remaining specimens were tested after six and twelve months of storage in distilled water at 37 °C. Data were analyzed with Two-way ANOVA and Holm–Sidak method. After 24 h of storage, mean bond strength values were not significantly different among all groups (p>0.05). Bond strengths of EGCG and CHX remained stable after 6 and 12 months. (p>0.05). To conclude, pretreatment with EGCG or CHX preserved the bonding of Adper Easy One to dentin after six and twelve months of storage.     

Microtensile bond strength testing of resin cements

To investigate the microtensile bond strength (μTBS) and failure mode of resin cements bonded to ceramic blocks following various surface treatments.Seventy-two Ceramco II (Ceramco lnc., Burlington, NJ) ceramic discs 10 mm in diameter and 4 mm thick were prepared. The ceramic specimens received 8 different surface conditions treatments before the application of resin cement. These surface treatments were sanding with 600-grit silicon carbide paper, microetching with aluminum oxide, sanding followed by silane application, microetching followed by silane application, hydrofluoric acid etching, hydrofluoric acid etching followed by silane application, application of adhesive resin, and combination of the previous two treatments (HF+S+Adh). Seventy-two extracted molars were ground flat at 90° to the long axis of the tooth until a sufficient circular area of dentin was exposed (at least 5 mm in diameter). Three resin cements were applied to these surfaces. After 24 h storage at 37 °C, the non-trimming version of μTBS test was used to produce 1 mm² microbars. The microbars were subjected to a tensile load using a modified testing device.Data were analyzed with 2-way analysis of variance. The interaction between the substrate surface treatment and cement type is significant (p<0.001).The results of this in vitro study suggest that when the tested ceramic restoration is cemented with a resin cement system, the ceramic should be etched with hydrofluoric acid, silane and adhesive should be applied prior to cementation. The results also suggest that an auto- or light-polymerizing cement should be considered instead of a dual-polymerizing cement.     

Effect of zinc chloride added to self-etching primer on bond strength to caries-affected dentin and chemical-physical-mechanical properties of adhesives

The aim of this in vitro study was to evaluate the effect over time of zinc chloride (ZnCl₂) incorporated into the primer of a two-step self-etching adhesive system (Clearfil SE Bond, Kuraray - SE) on long-term microtensile bond strength (μTBS) to caries-affected dentin (CAD), and on flexural strength (FS) and conversion degree (CD) of the adhesive. First, the CD of SE with and without 2% (wt) ZnCl₂ solution was evaluated by Fourier transform infrared spectroscopy (FTIR). Then, beam-shaped samples (7 mm × 2 mm x 1 mm) were prepared with the SE primer containing the ZnCl₂ solution, to perform flexural strength (FS) tests. For μTBS testing purposes, CAD surfaces were randomly divided into two groups, according to the presence of ZnCl₂ powder (2 wt%) incorporated into the adhesive system (ZnCl₂), or its absence (NT). An additional group consisting of dentin pretreated with a 2% chlorhexidine digluconate (CHX) solution was proposed as a positive control (n = 10). A two-step self-etching system (SE) was applied following the manufacturer's instructions, and restorations of composite resin were built up on the dentin. After 24 h, the resin-dentin blocks were sectioned into specimens that were submitted to μTBS testing immediately following, or after 12 months of water storage (WS). Both μTBS and FS tests were performed using a universal testing machine (0.5 mm/min). FS and CD data were submitted to the Student t-test, and μTBS data were submitted to two-way ANOVA and Tukey's test (α = 0.05). ZnCl₂ incorporation had no statistically significant influence on flexural strength (p = 0.88) or conversion degree (p = 566). Regarding μTBS, no significant effect of the double interaction of “dentin treatment” versus “WS period” (p = 0.546) was observed. The bond strength was not affected by the WS period (p = 0.805). The highest mean bond strength was observed for the NT group, which did not differ from the ZnCl₂ group. The lowest mean bond strength was observed for the CHX group, which differed statistically from the NT group (p = 0.053). It was concluded that incorporation of ZnCl₂ into the SE self-etching primer did not interfere in the bond strength of caries-affected dentin, in regard to failure mode, flexural strength or CD, and had no other beneficial effects.     

Shrinkage stress,long-term adaptation and bond strength of low-shrinkage composite resins

PurposeTo evaluate the internal adaptation, bond strength, and polymerization stress of silorane- and methacrylate-based composite resins.Material and methodsThree methacrylate-based composite resins (Heliomolar; Tetric N-Ceram and Aelite LS) and one silorane-based composite resin (Filtek Silorane) were tested. Polymerization stress (n=5) was determined by the insertion of the composite resin between rods of polymethyl methacrylate. The ratio of the maximum force of contraction was recorded and the cross-sectional area of the rod was used to calculate the nominal stress. Bond strength was evaluated by microtensile bond test. Dentin surfaces of human third molars were bonded, sectioned, and stored for 24 h or 1 year in distilled water before the bond strength test. The ratio of maximum force and the adhered area was used for the bond strength calculation. For internal adaptation analysis, third molars received Class II cavities and were restored according to either an incremental oblique or bulk-filling technique. After being sectioned perpendicularly, impressions were taken and epoxy resin replicas were obtained of the internal surfaces of the restorations (after 24 h and 1 year of storage) to analyze gap formation using scanning electron microscopy.ResultsFiltek Silorane showed the highest​ bond strength after one year of storage, the lowest formation of gaps, and polymerization stress similar to methacrylate-based materials.ConclusionSilorane restorative material presented polymerization stress comparable to that of methacrylate-based composite resins, stable dentin bond strength after one year and better internal adaptation to the cavity walls, showing good alternative to traditional composite resins and promising longevity.     

Effect of self-etching dual-curing universal adhesive system application on bond strength of dentin resinous liners dentin

Purpose: The aim of this study was to evaluate the influence of previous application of an adhesive system on bond strength of resinous liner materials to dentin. Methods: Ninety bovine incisors crowns had a 6 × 6 mm area of dentin exposed, with minimum of 2 mm thickness. They were embedded in acrylic resin, and the dentin was polished with P600 SiC sandpaper for 30 s to standardize the smear layer. The specimens were divided into 6 groups (n = 15) according to the application or not of a self-etching system (Futurabond U – Voco) and the type of resinous liner used: A+Ionoseal (adhesive and Ionoseal – Voco); Ionoseal (Ionoseal only); A+Vitrebond (adhesive and Vitrebond – 3M/ESPE); Vitrebond (Vitrebond only); A+Ionosit (adhesive and Ionosit – DMG) and Ionosit (Ionosit only). Adhesives were used following manufacturer’s instructions, and the liner materials were applied inside a 2-mm-depth matrix and light-cured for 20 s. The bond strength was measured by microtensile test, using a universal testing machine with a cross-speed of 1 mm/min. Data were analyzed using one-way ANOVA and Tukey’s test (p < 0.05). Results: The adhesive system application increased bond strength of all liners tested. Ionoseal presented the highest bond strength when the adhesive system was used and exhibited similar performance to Vitrebond without adhesive. Ionosit without adhesive showed the smallest bond strength compared with the other liners tested. Conclusion: The application of an adhesive system prior to the use of the resinous liners improved the bond strength to dentin and should be preconized.     

The influence of blood and/or hemostatic agent contamination on Micro-TBS to dentin

Aim: The purpose of this study was to evaluate the effects of blood contamination and hemostatic agent Ankaferd Blood Stopper (ABS: Ankaferd Drug Inc, Istanbul, Turkey) on the microtensile bond strength of a self-etching adhesive. Material and methods: Flat dentin surfaces were created from 40-M teeth and randomly divided to four groups according to contamination and adhesive procedure. The specimens of Group 1 are contaminated with blood; ABS was applied to the specimens of Group 2 after blood contamination and applied to the specimens of Group 3 without blood contamination. Group 4 is control group and self-etching adhesive was applied to all specimens. Teeth were restored with a nanohybrid composite. The specimens were sectioned to the beams and microtensile testing was carried out and the data were statistically analyzed with analysis of variance test. Tukey’s honestly significant difference post hoc test was also performed for multiple comparisons to compare subgroups. Results: Group 4 had the highest strength value, followed by Group 3, while Group 1, which contacts only with blood, had the lowest strength value. Conclusion: ABS has a negative effect on the bond strength of one-step self-etching adhesive system.     

Bond Strength and Interfacial Ultramorphology of Current Adhesive Systems

This study evaluated the bond strength and ultramorphology of the resin-dentin interfaces produced by current dental adhesive systems. Nine dentin bonding agents were investigated. Restored teeth were vertically, serially sectioned to obtain bonded slices for interfacial TEM analysis or to produce bonded beams for the microtensile bond strength test. The one-step self-etching adhesives (Futurabond® NR and Hybrid Bond®) showed lower bond strength values than the three-step etch-&-rinse adhesive system All-Bond 3. Most bonding agents presented statistically similar mean bond strength values, which ranged from 41.3 ± 17.9 to 35.0 ± 5.3 MPa. The thickness of the hybrid layer varied according to the type of adhesive system used. While the etch and rinse adhesives with alcohol as organic solvent showed bond strength means higher than 40 MPa, the self-etching systems showed bond strength lower than 40 MPa. Resin-dentin interdifusion zone and resin tags were noted in all bonded interfaces.     

The effect of different cementing strategies and adhesive interface aging on microtensile bond strength (μTBS) of lithium disilicate ceramics to dentin

This study evaluated the effect of different cementing strategies and adhesive interface aging on microtensile bond strength (μTBS) of lithium disilicate ceramic (IPS e.max CAD) to dentin. Forty coronal dentin fragments were randomly assigned to four groups according to the cementing strategy used to bond lithium disilicate ceramic to coronal dentin surface (n = 10): U200 (self-adhesive resin cement (RC) RelyX U200®/3 M ESPE), SBU (single-step self-etching adhesive system (AS) Single Bond Universal®/3 M ESPE + RelyX ARC®/3 M ESPE RC), AdperSB (two-step etch-and-rinse AS Single Bond 2®/3 M + RelyX ARC®/3 M ESPE RC) and Scotchbond (three-step etch-and-rinse AS Scotchbond Multi-Purpose®/3 M + RelyX ARC®/3 M RC). After 48 h, the ceramic-tooth blocks were sectioned perpendicular to the adhesive interface in the form of sticks and randomly subdivided into two groups according to when they were to be submitted to μTBS testing: immediately or 6 months after storage in water. Some sticks were kept for analysis of the adhesive interface by scanning electron microscopy (SEM). The μTBS test was performed in a universal testing machine (0.5 mm/min). The data (MPa) were analyzed using split-plot ANOVA and Tukey’s test (α = 0.05). Water storage decreased μTBS in all cementing strategies. The μTBS was greatest in the Scotchbond group and lowest in the U200 group, at both storage times. No signs of interface degradation were detected under SEM after water storage. In conclusion, water storage decreased bond strength, regardless of the adhesive cementation strategy, and that the three-step adhesive system/dual-cure resin cement ultimately performed better in terms of bond strength.