Effect of an Er,Cr:YSGG laser preparation on dentin bond strength of a universal adhesive

The aim of this study was to evaluate the bond strength of a universal adhesive system to dentin prepared with SiC paper or an Er,Cr:YSGG laser using different bonding strategies (etch-and-rinse versus self-etch mode). Ninety-six extracted caries-free, sound human molars were used. The teeth were longitudinally sectioned in the mesiodistal direction and were wet polished with 600-grit SiC paper to obtain a standardized flat dentin surface. All prepared teeth were randomly divided into two groups, according to the surface preparation method: GroupI:an erbium, chromium:yttrium,scandium, gallium, garnet laser; Group II: silicon carbide paper[SiC] (n = 48). Each group was then assigned into three subgroups according to the universal adhesive’s (Single Bond Universal) bonding strategies: (a) etch-and-rinse mode with phosphoric acid, (b) etch-and-rinse mode with a laser, (c) self-etch mode (n = 16). For surface preparation, the Er,Cr:YSGG laser was used at 3 W, 30 Hz with 140 μs pulse duration for 25 s. For etching mode, the laser was used at 1.5 W (60% air, 70% water). Cylinders of composite were fabricated on the bonding area and shear bond strength was determined using a universal testing machine. Failure modes were evaluated using a stereomicroscope. The data were analyzed using two-way ANOVA followed by the Bonferroni test (p < 0.05). Bonding strategies showed statistically significant differences in both the SiC-and laser-prepared groups (p < 0.05).Universal adhesive used in etch-and-rinse mode with acid showed significantly higher bond strength values than in self-etch mode (p < 0.05). The bond strength values did not differ according to the surface preparation method (p > 0.05). Irrespective of preparation method, using universal adhesive in etch-and-rinse mode with acid might improve dentin bond strength. Laser preparation did not affect the bond strength of the universal adhesive tested.     

Effect of caries removal techniques on bond strength to caries affected dentin on gingival wall: AFM observation of dentinal surface

Objective: The purpose of this study was to evaluate the effect of different caries removal techniques on the bond strength of two adhesive systems. Materials and Methods: Seventy human molar teeth that had proximal carious lesions were randomly divided into four groups according to the technique used to remove the caries: a conventional steel bur, an Er:YAG laser, a chemomechanical Carisolv^® gel, and air polishing. The groups were then divided into two subgroups according to the adhesives used: Clearfil S³ (Kuraray Co., Ltd, Tokyo, Japan) and Adper SE Plus (3 M ESPE, St Paul, MN, USA). The enamel and superficial dentin of the crown was flattened and caries were removed using different methods. Teeth were restored with composite and three 1 mm² stick-shaped microtensile specimens were prepared from each tooth. For each removal technique, the surface roughness of one dentin sample was analyzed using atomic force microscopy (AFM). The microtensile bond strength data were then analyzed using a two-way ANOVA, Kruskal–Wallis and Mann–Whitney U tests, and multiple comparison tests (p = 0.05). Results: The two-way ANOVA showed that the effects of the cavity preparation techniques and adhesive systems and their interaction were statistically significant (p < 0.05). The μTBS values were highest when bonding with Adper SE Plus to cavities prepared with the steel bur (37.20 ± 11.65 MPa) and lowest when bonding with Clearfil S³ Bond to cavities prepared with the Er:YAG laser (16.74 ± 6.95 MPa). Conclusion: The caries removal techniques affected the bond strength values of the self-etch adhesive systems.     

Post-treatment with high-power lasers to improve bond strength of adhesive systems to bleached dentin

To assess the effect of Er:YAG and diode lasers on the shear bond strength (SBS) of adhesive systems to bovine dentin submitted to bleaching with a high concentration agent. One hundred and twenty bovine dentin fragments were used. Fragments were distributed into 12 groups (n = 10) considering the bleaching (present or not), surface post-treatment (untreated, Er:YAG laser or diode laser) and adhesive system (total-etching or self-etching). Specimens received two applications of 38% hydrogen peroxide. Er:YAG laser (2940 nm, 200 mJ, 4 Hz) and diode laser (980 nm, 1.5 W) were applied for 15 s on bleached dentin surface. Restoration was performed with resin using split matrix. Specimens were submitted to SBS test and data (MPa) were analyzed by ANOVA and Tukey’s test (α = 0.05). SBS of bleached specimens decreased in comparison with non-bleached (p < 0.05). The highest values were obtained for the post-treatment with Er:YAG laser (p < 0.05). Total-etching adhesive was superior to self-etching system (p < 0.05). The irradiation of bleached dentin with Er:YAG laser followed by the application of the total-etching adhesive had similar SBS to unbleached dentin with no post-treatment (control) (p > 0.05). Er:YAG laser post-treatment followed by the total-etching adhesive system improve the bond strength of restorative material to bleached dentin.     

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.     

Which is effective on bond strength of resin-based sealers: incorporation of powdered dentin to primer or adhesive?

The aim of this study was to investigate the effect of adding powdered dentin to primer or adhesive in a self-etch system on the shear bond strength of three resin-based sealers. Seventy-two premolars were sectioned buccolingually, and 144 root halves were divided into three groups according to the sealer used: epoxy resin-based sealer (AH Plus), methacrylate resin-based (RealSeal, Hybrid Root SEAL) n = 48. The surfaces were irrigated with 5% NaOCl, 17% EDTA, distilled water for 5 min. Four subgroups were created (n = 12): control group; Clearfil Liner Bond 2 V treated group; powdered dentin added to the primer of Clearfil Liner Bond 2 V (40 wt.%); and powdered dentin added to the adhesive of Clearfil Liner Bond 2 V (20 wt.%). Dentin powder was prepared. Three mm high buildups with a constant surface area of 3.45 mm² were created using the sealers and allowed to set (37 ºC, 100% humid, 72 h). The samples were tested to failure for shear bond strength (1 mm/min). The data were calculated (MPa) and analyzed using two-way ANOVA, one-way ANOVA, and Tukey HSD tests. Adhesive use decreased the bonding performance of AH Plus (p = 0.00). Mean bond strength of the other sealers was found similar to control. Primer or adhesive resin with powdered dentin did not increase the adhesive performance of the self-etch system used. The shear bond strength of RealSeal was significantly increased when powdered dentin was added to primer or adhesive (p = 0.00). The effect of adding powdered-dentine to primer or adhesive in a self-etch system on the shear bond strength was sealer-dependent .     

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.     

Influence of phosphoric acid etching on the dentin bond durability of universal adhesives

This study aimed to compare the microshear bond strength (MSBS) of three universal adhesives and a three-step conventional adhesive to dentin after 24-hour and one-year storage in water. A new fluoride-releasing universal adhesive (Clearfil Universal Bond Quick: CUQ) and two commercially available adhesives (ScotchBond Universal: SBU and All-Bond Universal: ABU) were evaluated with phosphoric acid etching (PA-etch mode) or without it (self-etch mode). All-Bond 3 (AB3) served as control group. After bonding composite cylinders to dentin discs obtained from caries-free human teeth, the specimens were stored in deionized water at 37?°C for either 24 hours or one year (n?=?14) before MSBS measurement. Two-way ANOVA analysis of the results showed that the adhesives, storage time and their interactions had a significant effect on MSBS (p?<?0.01). In self-etch mode, there was no significant difference among universal adhesives at the baseline. In PA-etch, the CUQ and SBU showed significantly higher MSBS compared with AB3 (p?<?0.05). At baseline, no difference was found between the two modes for each universal adhesive (p?>?0.05). After one year, CUQ in self-etch mode showed a slight increase in nominal MSBS (p?>?0.05) and Weibull characteristic strength, which was significantly higher than SBU and ABU in the corresponding mode. There was no difference among the three universal adhesives in PA-etch mode after one year (p?>?0.05). In conclusion, the durability and reliability of dentin bonding with universal adhesives in different application modes depended on the material; and the self-etch approach showed promising results for the tested fluoride-releasing universal adhesive.     

Influence of pH cycling and mechanical loading on the resin-dentin microtensile bond strength

The durability of adhesive interfaces is still a problem in adhesive restorations in dentistry. Laboratorial ageing methods have been proposed to predict the performance of materials, but they still require standardization. The objective of this study was to evaluate the resin-dentin microtensile bond strength of composite restorations subjected to pH cycling and different levels of mechanical loading. Resin blocks were built over a flat superficial dentin of bovine incisors (n = 40), using a three-step adhesive system. Half of the specimens were submitted to 10 cycles of pH cycling, followed by mechanical loading (0, 500,000; 1,000,000; 2,000,000 cycles – 98 N, 4 Hz). The other half was directly subjected to mechanical loading. After ageing, all groups were subjected to a microtensile bond test. Data were analyzed using two-way ANOVA and Tukey’s test (α = 0.05). The frequency of the early de-bonding was compared using the Chi-square test (α = 0.05). The statistical analysis revealed that the cross-product interaction ‘pH cycling’ vs. ‘number of mechanical loading cycles’ (p = 0.72) as well as the main factor ‘pH cycling’ (p = 0.49) was not statistically significant, and they were not able to reduce the resin–dentin bond strength values. Regarding the number of mechanical loading cycles, the groups subjected to 2,000,000 cycles showed lower bond strength values than the others (p = 0.003). The frequency of debonded specimens increased with mechanical loading. Therefore, it can be concluded that in this restorative model, at least 2,000,000 mechanical cycles are need to decrease the microtensile strength and simulate the ageing of the interface.     

Efficacy of accelerated aging methods to degrade the adhesive interface of dentin cavities bonded with etch-and-rinse adhesive systems

This study evaluated the bond durability produced by etch-and-rinse (E&R) adhesive systems in response to traditional and accelerated aging methods. Tridimensional dentin cavities were prepared on 80 bovine incisors, which were bonded with a 3-step E&R (Adper Scotchbond Multipurpose Plus – MP) and a 2-step E&R (Adper Single Bond 2 (SB) adhesive systems, and restored with composite. The samples were stored in water for 24 h, and then subjected to each of the aging methods (n = 10): control group – only 24-h storage (not exposed to additional aging), 6- and 12-month water storage, and 10% NaOCl storage. The push-out bond strength test was performed in a universal testing machine. Failure modes were evaluated by scanning electron microscopy. Data were analyzed by two-way ANOVA and Tukey tests (p < 0.05). Aging methods provided statistically similar bond strength for 3-step E&R adhesive system (p > 0.05). 10% NaOCl storage provides statistically similar bond strength values to 6- and 12-month water storage (p > 0.05), which were statistically lower than those provided by 24-h water storage (control group) (p < 0.05). Adhesive failures were more frequent. Aging methods provided different behaviors according to each adhesive system. The accelerated 10% NaOCl storage was effective to decrease bond strength only for 2-step E&R adhesive system.     

Effect of fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate on bond strength to enamel

To investigate the effect of fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate on the shear bond strength (SBS) of two adhesive systems to enamel. Specimens obtained from permanent teeth were randomly distributed among four groups for enamel pretreatment [Control (no treatment, CNT), Duraphat varnish (DV), Clinpro White varnish (CWV), MI Varnish (MIV)], and each group was further divided into two subgroups according to adhesive [Etch&rinse (Adper Single Bond, ASB), self-etch (Clearfil SE Bond, CSE)]. Specimens were stored in distilled water at 37 °C for 24 h. Cylindrical composite specimens (2.3 mm in diameter, 3.0 mm in height) were then bonded to the enamel surfaces. SBS tests were performed and data were analyzed with two-way ANOVA and Tukey’s tests. For both CSE and ASB, SBS values of the CNT groups were significantly higher than those of all the enamel pretreatment groups (p < 0.05). Among the enamel pretreatment groups, SBS values with both adhesive systems were lowest in the MIV groups, followed by CWV and DV groups. In conclusion, pretreatment of enamel surfaces with fluoride-containing varnishes reduced bonding performance of adhesive systems to enamel. MIV appeared to cause greater enamel surface alterations and precipitation, which interfered with adhesive bonding mechanisms.     

Effect of different application techniques on microshear bond strength of self-etch adhesives to dentin

Objectives: To investigate the effect of different self-etch adhesive systems application techniques: active or passive in a single or double layer on adhesive–dentin microshear bond strength.

Methods: Occlusal surfaces of 48 extracted human molars were ground to expose flat superficial dentin surfaces. Specimens were randomly divided into two main groups according to the tested self-etch adhesive system either: One-step self-etch (Adper^TM easy-one) or two-step self-etch (Adper^TM SE Plus). Each adhesive system was applied on the prepared dentin surfaces followed one of these techniques: (1) Passive application of a single layer, (2) Active application of single layer, (3) Passive application of double adhesive layer (with light curing in between), and (4) Active application of double adhesive layers. Resin composite was packed inside micro-tubes fixed on the bonded dentin surfaces and light cured for 40 s. All specimens were stored in artificial saliva either for 24 h or 3 months before testing. Microshear bond strength test was employed using a universal testing machine at a crosshead speed of 0.5 mm/min.

Results: Adper^TM SE Plus showed higher significant microshear bond strength in compared with Adper^TM easy-one. For both adhesive systems active application showed higher significant microshear bond strength to dentin than passive application. Double application of adhesive systems showed lower microshear bond strength than single application.

Conclusion: Active application of self-etch adhesives could improve the dentin microshear bond strength. Double application with curing in between the layers did not improve the bond strength to the tested adhesive.     

Effects of cavity disinfectants on bond strength of an etch-and-rinse adhesive to water- or ethanol-saturated sound and caries-affected dentin

Objective: To evaluate the effect of cavity disinfectants on the immediate microtensile bond strength (μTBS) of an etch-and-rinse adhesive to water- and ethanol-saturated sound and caries-affected dentin (CAD). Material and Methods: Thirty-six human molars were sectioned to expose 1/3 of the mid-coronal dentin surface. Sound (n = 18) and CAD (n = 18) specimens were divided into six groups each (n = 3): one positive control (sound), one negative control (CAD), and five experimental groups each. In the control group, dentin surfaces were bonded using an etch-and-rinse adhesive with a traditional water-wet bonding technique. In the experimental groups, ozone was applied before etching and chlorhexidine after etching. In the ethanol-wet bonding groups, acid-etched dentin surfaces were treated with ethanol. Following adhesive application and composite buildups, bonded specimens were sectioned to form sticks. Failure modes were analyzed using a stereomicroscope. Results: The water-wet bonded sound control group yielded the highest μTBS among all groups (p < 0.001). The lowest μTBS values were observed in the ozone groups (p < 0.05). The ethanol-wet bonded CAD group exhibited a higher μTBS than the water-wet bonded negative controls. Although compared to the positive control, chlorhexidine decreased the μTBS (p < 0.05), an increase with no significant difference was observed in the negative control (p > 0.05). Conclusions: The μTBS values of CAD were lower than those of sound dentin. Ethanol-wet bonding improved the μTBS of CAD. Ozone application reduced the μTBS in both sound and CAD; chlorhexidine improved the immediate μTBS after etching in CAD.     

The Effect of Decalcified Root Surfaces on Dentinal Bond Strength

Microtensile bond strengths of current dentin adhesives to intact and decalcified root surfaces were evaluated. Two hundred and twenty-four extracted human incisors were divided into two groups as intact (IRD) and decalcified (DRD). The roots of DRD teeth were placed in a demineralization solution to produce artificial carious-like lesions. Root surfaces were slightly ground and treated with either Scotchbond Multi-Purpose (SMP), Adper Single Bond Plus (SBP), Adper Easy Bond (AEB), Scotchbond SE (SSE), Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Clearfil Tri-S Bond (CTS), FL-Bond II (FLB), XP Bond (XPB), iBond (IB), AdheSE Bond (ASE), Optibond Solo Plus (OSP), Prelude Dental Adhesive (PDA), and G-Bond (GB). Composite build-ups were formed on the bonded surfaces. After thermocycling, hour-glass shaped specimens with an area of 1 mm² at the bonded interface were subjected to microtensile testing. Resin–dentin interfaces were observed with SEM. Kruskal Wallis and Mann Whitney-U tests were used for statistical analysis. There was not significant difference between bond strengths to intact and decalcified dentin, with the exception of ASE and CSE, which had higher values to IRD (p < 0.05). SSE and CTS were the adhesives that showed higher bond strengths to DRD than to IRD, however the difference was not significant (p > 0.05). The self-etch adhesives performed better on both IRD and DRD surfaces than etch-and-rinse systems.     

Bonding ability of self-adhesive resin-cements after dentin biomodification with hyaluronic acid

Purpose: The present study evaluated the influence of the hyaluronic acid (HA) on the bonding ability of self-adhesive resin cements to dentin regarding the bond strength. Eighty bovine incisors were ground flat to obtain a 2-mm thick slices which received conical preparations. The specimens were randomly distributed into 4 groups (n = 15) according to the dentin pretreatment (1 – control: untreated dentin; 2 – application of HA) and the evaluation time (1 – control: immediate evaluation; 2 – hydrolytic degradation: 6 months of storage in water at 37 °C). Preparations received the application of a self-adhesive resin cement (RelyX U200 or MaxCem Elite). Push-out bond strength test was conducted (0.5 mm/min). The bond strength data was submitted to two-way ANOVA/Tukey’s test (α = 0.05). For U200, no significance was observed when comparing the immediate (24 h) and 6 months means for the control groups (unexposed specimens). Previous application of HA to dentin significantly reduced the bond strength of U200 to dentin in both evaluation times (p < 0.05). HA had no significant influence on the push-out bond strength means for the cement MAX in both evaluation times (p > 0.05). The type 1 failure mode (adhesive mode) occurred in 100% of the specimens, irrespective of the dentin treatment or evaluation times. Pretreatment of dentin with HA produces a material-dependent influence on the push-out bond strength. The bonding ability of RelyX U200 is negatively influenced by the pretreatment of dentin with HA, whereas the biomodification of dentin with this bioactive agent causes no impact for the cement MaxCem Elite.     

NaOCl degradation of one-step one-bottle self-etch adhesives bonded to bovine dentine

Objective: The aim of the present study was to assess the influence of an in vitro aging regime (NaOCl storage) on dentine microtensile bond strength (μTBS) of five one-step one-bottle self-etch adhesives in comparison with bond strength of two-step self-etch adhesive.

Material and methods: Flattened dentine surfaces from 30 bovine incisors were bonded with five one-step one-bottle self-etch adhesives (iBond, Clearfil S3 Bond, AdheSE One F, G-Bond, Optibond all-in-one) and one two-step self-etching adhesive (Clearfil SE Bond). Composite buildups were done with microhybrid resin composite. Bonded samples were sectioned into resin–dentine sticks of 0.8 mm² cross section. Randomly selected 20 sticks were tested directly by microtensile bond strength testing machine, whereas another randomly selected 20 sticks were tested after being stored in solution of 10% NaOCl for 5 h. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests (p < 0.05).

Results: All adhesives exhibited similar dentine bond strength with exception of G-Bond. After NaOCl storage, μTBS reduced in all groups significantly. The lowest μTBS were found for G-Bond. Rest of one-step self-etch adhesives presented similar μTBS with two-step self-etch adhesive.

Conclusion: Interfaces of resin–dentine bonding are susceptible to NaOCl degradation. The amount of the destruction depends on adhesive system. NaOCl degradation of the nonresin encapsulated collagen fibers might decrease long-term stability of resin bonding with dentine.     

Effects of simulated pulpal pressure,mechanical and thermocycling challenge on the microtensile bond strength of resin luting cements

This study aimed at comparing the microtensile bond strength (µTBS) of three simplified luting strategies after different aging processes. Sixty human molars were prepared to expose flat middle dentin surfaces which received the following luting procedures: (i) SB+ARC – two-step etch-and-rinse adhesive+conventional resin cement (Adper Singlebond 2+RelyX ARC, 3M-ESPE); (ii) S3+PAN – one-step self-etch adhesive+conventional resin cement (Clearfil S3+Panavia F2.0, Kuraray Medical); (iii) U200 – self-adhesive resin cement (RelyX U200,3M-ESPE). The specimens were finally restored by indirect resin composite procedures (Filtek Z100,3M-ESPE). The aging regimens were water storage at 37 °C for one week (control), one week of 20 cm H₂O simulated pulpal pressure (SPP), 200,000 mechanical loading (ML) cycles, or 5000 thermal cycles (TC). The µTBS data was analyzed by two-way ANOVA and Tukey's test (α=0.05). SB+ARC showed significantly higher µTBS for control and all aging processes (p<0.001). Nevertheless, TC had no effect on the bond strength of SB+ARC. No difference in µTBS was observed between S3+PAN and U200 after SPP (p=0.251), but significant lower values were found for U200 after ML (p=0.010) besides being superior in the control groups (p<0.001). For U200, all ageing regimens induced significant reductions in the bond strength (p<0.001) with a more pronounced negative effect after ML. S3+PAN showed significant lower bond strength (p=0.010) only after ML aging. Two-step etch-and-rinse adhesive associated with dual-curing conventional resin cement may present the highest overall µTBS. However, the use of S3 one-step self-etch adhesive along with conventional resin cements may provide the most stable luting performance under the tested aging strategy.     

The effects of self-etch bio-active dental adhesive systems on bacterial microleakage

The aim of this in vitro study was to evaluate the effects of bio-active and non-bio-active self-etch adhesive sytems on bacterial microleakage of class II box cavities with restoration margins in dentin. Two bio-active (Clearfil Protect Bond and F1 Bond II) and two nonbio-active (Clearfil SE Bond and Clearfil s3 Bond) adhesive systems were selected for the study. Eighty mesial and distal class II box cavities were prepared on fourty sound human third molar teeth. The teeth were then divided into four groups with 10 teeth in each group. Groups were restorated using different adhesive systems. The restored specimens were immersed into a culture medium containing streptococcus mutans for bacterial microleakage test. Serial sections of the specimens were used to evaluate the bacterial lekage by using light microscope. The data obtained from the test of bacterial microleakage was evaluated using 2-way mixed analysis of variance (p < 0.05). Statistical analysis showed significant differences between the groups (p < 0.05). Nevertheless it was observed that none of the tested adhesive systems including the bio-active ones were successfull in eliminating bacterial microleakage.     

Bond strengths of bulk-fill resin composite repairs: effect of different surface treatment protocols in vitro

To evaluate the effect of different surface treatment protocols on the microtensile bond strength (μTBS) of bulk-fill resin composite repairs. Thirty-five bulk-fill resin composite samples (Filtek Bulk Fill) were prepared (5 × 5 × 5 mm) and aged by thermocycling (X5000). Samples were randomly divided into five groups (n = 7): a control (no treatment) and four surface treatment groups (Single Bond Universal [SBU]; phosphoric acid (37%) + SBU; Er,Cr:YSGG laser + SBU; aluminum oxide sandblasting + SBU). Filtek Ultimate Universal composite was used as a repair material. After storage for 24 h in distilled water (37 °C), sticks were obtained and subjected to a μTBS test. The data (MPa) were analyzed by one-way ANOVA with a post hoc test (α = 0.05). Failure mode was evaluated using a light microscope (10×). There were significant differences between the groups (p < 0.05). The lowest bond strength values were obtained in the control group (p < 0.05). No significant difference was observed between Group II (universal adhesive) and Group III (acid etch + universal adhesive) (p > 0.05). The bond strength of Group II was significantly lower than that of the other surface treatment groups (p < 0.05). While Group III showed significantly lower values than those of the laser treatment group (Group IV), similar values were obtained with Al₂O₃ sandblasting group (Group V). The highest repair bond strength was obtained in Group IV (p < 0.05) which was not significantly different from the Al₂O₃ sandblasting group (p > 0.05). The predominant failure mode was adhesive. Treatment of aged bulk-fill resin composite surfaces with laser and Al₂O₃ sandblasting provided higher repair bond strength values.     

Effect of different dentin adhesives and application modes on sealing ability of amalgam restorations

Purpose: The aim of the study was to evaluate the sealing ability of bonded amalgam restorations using different adhesive materials with different adhesive application methods including amalgam bonding application. Materials and methods: The prepared Class-V cavities were randomly assigned to four application groups of four tested dual-curing dentin adhesives (Scotchbond Multi-Purpose Plus, XP Bond, Xeno IV and Clearfil Liner Bond 2V), dual-curing resin-based cement (Panavia F2.0) and a control group (unlined amalgam). Group 1 adhesives were applied according to the instructions for direct light-curing, Group 2 chemical-curing mode was applied according to the manufacturer’s amalgam bonding instructions. Group 3 adhesives were first applied in light-curing mode, and then amalgam bonding adhesive was applied. Group 4 adhesives were first applied in chemical-curing mode, followed immediately by light-curing mode. After that, amalgam adhesive parts were applied; then, the amalgam was condensed and carved. After storage for 24 h in distilled water at 37 °C, restorations were finished and polished. The teeth were then thermocycled (500 cycles between 5 and 55 °C), and the specimens were examined for microleakage using methylene blue as a marker. Results: Compared to the control group, the adhesive application modes significantly reduced microleakage for both dentin and enamel margins (p < 0.05). In dentin margins of the adhesives tested, Group 4 showed the lowest leakage score. On the enamel margins for Scotchbond Multi-Purpose Plus and XP Bond, Group 1 showed the highest microleakage (p < 0.05). Conclusion: According to marginal sealing ability and ease of application, Group 2 was recommended for the etch and rinse systems, and Group 4 was also recommended for the self-etch systems under amalgam restorations.     

Adhesion of resin composite to enamel and dentin: a methodological assessment

This study compared the impact of four test methods on adhesion of resin composite to enamel and dentin. Human molars (N = 54) were randomly assigned to test the adhesion of resin composite material (Quadrant Universal LC) using one of the following test methods: (a) macroshear test (SBT; n = 16), (b) macrotensile test (TBT; n = 16), (c) microshear test (μSBT; n = 16) and (d) microtensile test (μTBT; n = 6). In a randomized manner, buccal or lingual surfaces of each tooth, were assigned as enamel or dentin substrates. Enamel and dentin surfaces were conditioned using an etch-and-rinse adhesive system (Syntac Classic). After storage (24 h, 37 °C), bond tests were conducted in a Universal Testing Machine (1 mm/min) and failure types were analyzed. Data were analyzed using Univariate and Tukey`s, Bonneferroni tests (α = 0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. Test method (p < 0.001) and substrate type (p < 0.001) significantly affected the results. When testing adhesion of resin composite to enamel, SBT (25.9 ± 5.7)^a, TBT (17.3 ± 5.1)^a,c and μSBT (27.2 ± 6.6)^a,d test methods showed significantly higher mean bond values compared to μTBT (10.1 ± 4.4)^b (p < 0.05). Adhesion of resin composite to dentin did not show significant difference depending on the test method (12 ± 5.7–20.4 ± 4.8; p > 0.05). Only with SBT, significant difference was observed for bond values between enamel (25.9 ± 5.7) and dentin (12 ± 5.7; p < 0.05). Weibull distribution presented the highest shape values for enamel-μSBT (29.7) and dentin-μSBT (22.2) among substrate-test combinations. Regardless of the test method, cohesive failures in substrate were more frequent in enamel (19.1%) than in dentin (9.8%).