Multi-Purpose Plus Research Articles

Bond Strength of Two Resin Cements with Leucite-reinforced Ceramic Using Different Bonding Agents.

To compare the bond strength of two resin cements to leucite-reinforced ceramics using three different boding agents and evaluate the compatibility of bonding agents. Twenty extracted sound human molars were sectioned horizontally 2-3 mm above the cementoenamel junction (CEJ). CAD/CAM ceramic blocks for inLab were also sectioned to create 4 mm thick and bonded to the dentin. The adhesive groups assigned were divided into four adhesive groups: Group I: Variolink II dual-cure resin cement and Scotchbond Multi-Purpose Plus adhesive, group II: Multilink Automix dual-cure resin cement and Multilink primers, group III: Multilink Automix and Clearfil SE bond 2 (CSE2) adhesive, group IV: Multilink Automix and CSE2 with light curing after adhesive application. Five specimens of each group were sectioned perpendicular to obtain six microsticks of 1 × 1 mm width from each sample. Microtensile bond strength data were expressed in MPa. Fracture modes (FrMs) analyzed for the surfaces were divided into six patterns. Microtensile bond strength data were statistically analyzed with one-way ANOVA and Tukey post hoc tests (α = 0.05). T-test was performed at the 5% significance level to analyze groups III and IV with and without light curing. Group I showed the highest μTBS average of 13.67 MPa, group IV showed 12.26 MPa, group III showed 12.15 MPa, and group II showed the lowest average of 10.84 MPa. No significant differences were found between the bonding agents. However, the six types of failure modes, although all observed, were characterized by the adhesive system: Type I: adhesive failure of laminated dentin and ceramic; type II: adhesive failure of laminated ceramic; type III: adhesive failure of laminated dentin; type IV: cohesive failure of luting agent; type V: cohesive failure of dentin, and type VI: mixed failure of adhesion and cohesion. As a result, the FrM most commonly observed was the adhesive failure at the luting cement-ceramic block interface. The combination of resin cements and bonding agents did not significantly affect the bond strength of CAD/CAM ceramic restorations and dentin. Several universal bonding agents are currently available for direct and indirect bonding, and using the same bonding agent for direct and indirect restorations could simplify inventory and benefit routine clinical practice. How to cite this article: Aida N, Koi K, Amaya-Pajares SP, et al. Bond Strength of Two Resin Cements with Leucite-reinforced Ceramic Using Different Bonding Agents. J Contemp Dent Pract 2023;24(11):859-863.

Bonding stability of universal adhesives to feldspathic ceramic with or without prior silane application.

This study aimed to assess the bonding stability of three universal adhesives to a CAD-CAM feldspathic ceramic with or without prior silane application. The universal adhesives tested were Ambar Universal (FGM), Single Bond Universal (3M), and Ybond Universal (Yller). Scotchbond Multipurpose Plus (3M) was used as a control. The silane used was RelyX Ceramic Primer (3M). Microtensile bond strength (μTBS) to Vitablocs Mark II was measured after 24 h or 6 months of water aging (n = 20). Failure modes were observed through scanning electron microscopy, and pH and degree of C = C conversion (DC) of the adhesives were measured (n = 3). Data were analyzed using One-, Two-, and Three-Way ANOVA. The pH values differed significantly among the adhesives (P<0.001), while the DC was similar (P = 0.141). The universal adhesives showed significant differences in μTBS, with higher immediate results when using silane and lower results after aging. Notably, a significant decrease in μTBS was observed after 6 months when silane was applied. In contrast, the control adhesive exhibited consistent results between the 24-hour and 6-month storage periods. The universal adhesives showed a decrease in μTBS ranging from 25.5% to 40.1% after prolonged storage. Adhesive failures were predominant in all groups. The presence or absence of silane in the adhesive composition did not affect the bonding performance. The application of a separate silane coupling agent improved the immediate bond strength of universal adhesives to CAD-CAM feldspathic ceramic. However, this bond strength significantly decreased after 6 months of water aging. The bond strength remained stable for universal adhesives when applied without silane after 6 months of aging. This article is protected by copyright. All rights reserved.

Dual-cured adhesive system improves adhesive properties of dentin cavities restored with a bulk-fill resin composite

Aim: To evaluate the impact of a dual-cured adhesive system on the in situ degree of conversion (DC), bond strength (BS) and failure mode (FM) of adhesive interfaces in dentin cavities restored with a bulk-fill resin composite. Methods: 4-mm-deep dentin cavities with a 3.1 C-factor were created in 68 bovine incisors (n = 17 per group). The lightcured (Scotchbond™ Universal) or the dual-cured (Adper™ Scotchbond™ Multi-purpose Plus) adhesive system was applied to the cavities, which were then restored with a bulkfill resin composite (Filtek™ Bulk Fill). In situ DC analysis was performed by means of micro Raman spectroscopy at the top and bottom interfaces. Push-out BS was measured in a universal testing machine after 24-h or 6-month water storage. FM was determined with a stereomicroscope. Data of in situ DC and BS were analyzed by two-way analysis of variance (ANOVA) and Tukey test (p&lt;0.05), while the FM was analyzed descriptively. Results: The groups that received the dual-cured adhesive system showed statistically higher in situ DC and BS than those that received the light-cured adhesive system. Cohesive failure mode was the most frequent in all conditions. Conclusion: In situ DC and BS were influenced by the curing strategies of the adhesive systems with better performance of the dual-cured material.

Bond Stability of Universal Adhesives Applied To Dentin Using Etch-And-Rinse or Self-Etch Strategies.

This study evaluated the immediate and 6-month dentin bond strength of universal adhesives used in etch-and-rinse or self-etch bonding strategies. The adhesives tested were Ambar Universal, G-Bond, Single Bond Universal, Tetric N-Bond Universal, and Ybond Universal. Gold standard adhesives (Scotchbond Multipurpose Plus and Clearfil SE Bond) were controls. Microtensile dentin bond strength (n=5 teeth), pH, and C=C conversion (n=3) were evaluated. Data were analyzed at α=0.05. All adhesives showed differences in pH. Ybond had intermediately strong aggressiveness, whereas the others were ultra-mild. The C=C conversion was different in most adhesives. In the etch-and-rinse strategy, all adhesives showed similar results generally except for G-Bond, which had lower bond strength than most adhesives. G-Bond and Tetric-N-Bond showed lower bond strengths after 6 months compared with 24 h, whereas the other adhesives had stable dentin bonds. In the self-etch strategy, G-Bond had lower bond strength than most adhesives. After 6 months, Ambar was the only adhesive showing lower dentin bond strength compared with 24 h. Most adhesives had discreet drops in bond strength during aging when used in the self-etch strategy. The failure modes were also material dependent, with a general pattern of increased adhesive and/or pre-testing failures after storage. In conclusion, the bonding performance of universal adhesives to dentin is material dependent. Most adhesives had stable dentin bonds with results comparable to the gold standard materials, particularly when applied in the self-etch mode. In general, it seems the use of universal adhesives in dentin should not be preceded by phosphoric acid etching.

Resin-Based Materials Protect Against Erosion/Abrasion-a Prolonged In Situ Study.

While patient compliance is key to preventive measures related to dental erosion, the application of resin-based materials could serve as an additional treatment to inhibit erosion progression. This in situ study evaluated the effect of applying resin-based materials, including resin infiltrant, on previously eroded enamel subjected to prolonged erosive and abrasive challenges. The factors under study were types of treatment (infiltrant [Icon], sealant [Helioseal Clear], adhesive [Adper Scotchbond Multi-Purpose Plus], and control [no treatment]); wear conditions (erosion [ERO] and erosion + abrasion [ERO + ABR]) and challenge time (5 and 20 days) in a single-phase study. The blocks were prepared from bovine enamel, eroded (0.01 M HCl, pH 2.3 for 30 seconds) and randomized among treatments, wear conditions, and volunteers. The application of resin-based materials followed the manufacturers' recommendations. Twenty-one volunteers wore the palatal intraoral device, in which one row corresponded to ERO and the other to ERO + ABR. In each row, all treatments were represented (2 blocks per treatment). For 20 days, the erosive challenge was performed 4 times/day (immersion in 0.01 M HCl, pH 2.3, for 2 minutes) for the ERO condition. For the ERO + ABR condition, two of the erosive challenges were followed by abrasion for 15 seconds with fluoride dentifrice slurry. Enamel and/or material loss was measured using profilometry (initial, after treatment, and after the end of the fifth and 20th days of in situ erosive challenge) and analyzed by ANOVA models and Tukey's test (α=0.05). The results showed that the application of resin-based materials did not cause superficial enamel loss. The infiltrant group showed a thicker layer of material above the enamel compared with the other materials (p=0.001). After the erosive challenge, there was no difference between the conditions ERO and ERO + ABR (p=0.869). All materials protected the enamel against erosion progression compared with the control group (p=0.001). Based on these results, we conclude that the application of resin-based materials results in protection of previously eroded enamel subjected to in situ erosive and abrasive challenge for 20 days.

The Effect of Two Adhesive Agents on Shear Bond strength Between Fresh Dental Amalgam and Resin Composite

Objective: To assess and compare the results on the bond strength of two adhesive agents that bond fresh amalgam to two types of composite restorations, and to check the mode of bond failure.&#x0D; Methods: Sixty standardized circular cavities were prepared in a block of polymethyl methacrylate with standardized dimensions. Fresh amalgam was condensed to fill the cavity, then a gelatin mold with standardized dimensions was placed over the fresh amalgam,and the composite resin was bonded to the amalgam. Samples were assigned into three main groups, each containing (20) samples. G1: Amalgam bonded to composite without adhesive agent, G2: Amalgam bonded to composite by single bond universal adhesive, G3: Amalgam bonded to composite by scotch bond MPP, and each group was divided into two subgroups of (n=10) (Nanofill and Nanohybrid composite) to measure shear bond strength, which was followed by evaluation of debonding in all samples under a stereomicroscope to assess the mode of failure.&#x0D; Results: All The results showed that G3 has higher shear bond strength than G1 and G2, and this is statistically significant at (p=0.001, p=0.005) respectively, while G1 has the lowest shear bond strength and a statistically non-significant difference from G2 at (p=0.539). It was also found that the type of composite resin has no effect on bond strength and statistically non-significant difference was found for any of the sub-groups. Following debonding of all the samples, they were examined under a stereomicroscope, and the adhesive failure present was about (%65), and mixed failure present about (%35), while cohesive failure was (%0).&#x0D; Conclusions: Highest bond strength was found with Scotch bond multi-purpose plus (SBMPP) agent compared to other groups. The strength of the fresh amalgam bonding to the composite resin without an adhesive agent was low. The bond strength with single bond universal adhesive was lower than with the SBMPP system.

Evaluation of the accuracy of a modified microtensile test using micro-specimens

Purposeto evaluate the accuracy of a modified method of microtensile test (μTBS) through the performing of micro specimens (cross section 0.09 mm2) and to evaluate the interfacial integrity by confocal laser microscopy (CLSM). Material and methodstwo bond agents, Clearfil SE Bond and Scotchbond Multipurpose Plus were applied to flat dentin substrate of 32 human premolars and composite crowns were built up with Charisma Opal. The restored teeth were sectioned to produce beam-shaped specimens by diamond saw. For display in CLSM, 0.16 mg/ml of Rhodamine B was incorporated into adhesives thus forming two groups for each adhesive (n = 8) groups of teeth restored with adhesives stained and unstained. The presence of microporosities was recorded in CLSM before testing μTBS. The failure patterns were analyzed using SEM. Data of bond strength was submitted to two-way ANOVA. Resultsthe results showed bond strength data with low rate of premature failure, high percentage of failures at the actual interface (90%) and low coefficient of variation. No significant difference were observed between the specimens mean values of stained and unstained adhesives (p > 0.05). The CLSM revealed detailed information of the adhesive interface, showing low percentage of microporosities for both bonding agents. Conclusionbased on the results of different test parameters it can be inferred that the modified microtensile test performed with micro specimens, shown reliable and could be considered a valid method.

Resistance to Dislodgement of REBILDA® Post System to Intraradicular Dentin

Currently there is controversy in the literature about clinical and adhesive effectiveness with respect to adhesive systems aimed to root reinforcement. Thus, the objective of this study was to evaluate the Push-Out bond strength between the Rebilda® post system and the intraradicular dentine. Thus, 28 unirradicular teeth were used, cut and standardized in 16 mm. The root segments were submitted to endodontic treatment; and then randomly divided into two groups, Group 1 (n = 14): Rebilda® DC + Futurabond DC; Group 2 (n = 14): RelyX ARC + Adper Scothbond Multipurpose Plus. Ten specimens from each group were submitted to the Push-Out Test. The remaining 4 specimens from each group were prepared for Scanning Electron Microscopy (SEM) in order to evaluate the formation of resinous extensions at the post-cement-dentin interface. Group 2 showed better results when compared to Group 1 regarding bond strength and in formation of resinous extensions or tags, but there was no statistically significant difference (p&gt;0.05). It was concluded that the REBILDA® Post System promotes adequate bond strength to intraradicular dentin.

Bond Strength Evaluation of Two Adhesive Systems in Fiberglass Posts Cementation

Objective: To compare the bond strength of three-step and self-etch adhesive systems with and without prior acid etching on bonding of fiberglass posts in root canals. Material and Methods: Experiments were conducted on roots of five upper molars without curvature and sectioned in a cervical-apical direction. With the aid of a high-speed turbine and diamond tips, cylindrical cavities 7 mm in depth and 1.4 mm in diameter were made in the dentine. The roots of the same tooth were used, where the retainers were cemented, thus generating three groups: Group A: Adper Scotchbond Multipurpose Plus (SBMP) + Rely X ARC; Group B: Single Bond Universal (SBU-1) + Rely X ARC, with acid etching prior to adhesive insertion; Group C: Single Bond Universal (SBU-2) + Rely X ARC. The samples were stored in a bacteriological incubator at 37oC with 100% humidity for 48h and were subsequently cross-sectioned to obtain 3 dentine discs 1mm in thickness. Forty-five specimens were subjected to the push-out test. Results: Through the analysis of variance and Tukey's test, it was found that SBMP showed, with statistical significance (p<0.05), highest bond strength when compared with the SBU-1 and SBU-2 systems. The observed difference in the discs was located in the cervical portion. Conclusion: The three-step adhesive system had higher bond strength with the substrate than the self-etching adhesive only in the disc in the cervical portion; further, statistically, the prior application of phosphoric acid in SBU-1 did not affect its bond strength significantly.

Long-term bond strength of fiber posts cement to dentin with self-adhesive or conventional resin cements

The aim of this study was to evaluate the immediate and the long-term push-out bond strength of glass fiber posts (GFP) cemented with conventional or self-adhesive dual-curing resin cements, at different root depths. Prior to cementation, the GFP (Reforpost #3, Angelus) were etched with 37% phosphoric acid for 30 s followed by silane for 1 min. Thirty canine roots were divided into two groups (n = 15) according to resin cement type: ARC – dual resin cement (RelyX ARC/3M ESPE) combined with an three-step etch-and-rinse adhesive (Adper Scotch Bond Multi-Purpose Plus 3M/ESPE) or U200 – self-adhesive resin cement (RelyX U200/3M ESPE). The manufacturer’s instructions were followed. After 48 h, the roots were cross-sectioned at three different depths, resulting in serial slices corresponding to the cervical, middle, and apical root thirds. Slices were randomly divided into two groups, according to the period of water storage prior to push-out bond strength analysis: 48 h or 180 days. The data (MPa) were analyzed using three-way ANOVA for randomized blocks (p < 0.05), which showed no significant interaction between the three factors (p = 0.716). The main study factors were also proven not significant (cement: p = 0.711; time: 0.288; root third: p = 0.646). In conclusion, root depth, cement type (self-adhesive or conventional), and storage in water for 180 days did not influence the bond strength of GFP to intracanal dentin.

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 Dentin Pretreatment on Bond Strength Stability of Self-etching and Etch-and-Rinse Adhesives to Intracoronally Bleached Dentin.

To evaluate the effect of chlorhexidine or glutaraldehyde pretreatment on the bonding stability of selfetching and etch-and-rinse adhesives to bleached dentin. The occlusal surface of 80 third molars was abraded to expose a flat mid-dentin surface, which was then subjected to a bleaching procedure using 20% hydrogen peroxide and sodium perborate for 14 days. Afterwards, the specimens were kept in distilled water, followed by application of either a three-step etchand- rinse (Adper Scotchbond Multi-Purpose Plus, SBMP) or a two-step self-etching (Clearfil SE Bond, CSE) adhesive system. For each approach, the bleached dentin was treated with chlorhexidine or glutaraldehyde, or left untreated, prior to the adhesive procedure. Unbleached dentin was used as a control. Composite cylinders were built up over the adhesive-covered dentin followed by parallel sectioning of specimens to obtain 1-mm slices. The slices were trimmed to obtain hourglass-shaped specimens with approximately 1.0 mm2 of bonding interface. Half of the specimens were subjected to microtensile bond strength (μTBS) testing after 24 h, while the other half were stored in distilled water for 3 months prior to the μTBS test. The mode of failure was analyzed using optical microscopy. For the SBMP protocol, the highest μTBS was achieved with glutaraldehyde-treated dentin, and the same μTBS values were maintained after 3 months of storage. For the CSE protocol, the highest μTBS was obtained with chlorhexidine-treated dentin. Glutaraldehyde and chlorhexidine pretreatment should be considered to improve the μTBS of adhesives to bleached dentin, while the pretreatment effect was adhesive dependent.

Long-term effect of ethanol on the bond strength of fiber-glass posts to root dentin

Objective: To evaluate the long-term effect of ethanol (EtOH) application on the bond strength of adhesive systems used in post luting to root dentin. Methods: Bovine roots (n=40) had their root channel prepared for post luting and were etched with 37% phosphoric acid (15 s). Specimens were distributed according to adhesive system and EtOH application. Control groups received only the application of adhesives Adper ScothBond Multi-Purpose Plus (ASb), ou Adper Single Bond (SB). Experimental groups received previous EtOH application for 1 minute (EtOH+ASb and EtOH+SB groups). After fiber glass post luting, specimens were stored for 24 h, or 12 months, and later subjected to push-out test (n=5). Data were analyzed by three-way analysis of variance and Tukey test (α 0.05). After 12 months, it was observed significant statistically reduction of adhesive resistance (p 0.05). Conclusion: EtOH pre-treatment contributes to maintain the long-term bond strength, when water and ethanol-based adhesive system is used.

A 4-year clinical evaluation of direct composite build-ups for space closure after orthodontic treatment.

To evaluate the medium-term clinical performance of direct composite build-ups for diastema closures and teeth recontouring using a nano and a nanohybrid composite in combination with three- or two-step etch-and-rinse adhesives following treatment with fixed orthodontic appliances. A total of 30 patients (mean age, 19.5 years) received 147 direct composite additions for teeth recontouring and diastema closures. A nano and a nanohybrid composite (Filtek Supreme XT and CeramX Duo) were bonded to tooth structure by using a three-step (Scotchbond Multipurpose) or a two-step (XP Bond) etch and rinse adhesive. Ten out of 147 composite build-ups (composite addition) constituted tooth recontouring cases, and the remaining 137 constituted diastema closure cases. The restorations were evaluated by two experienced, calibrated examiners according to modified Ryge criteria at the following time intervals: baseline, 1, 2, 3, and 4 years. The 4-year survival rates were 92.8 % for Filtek Supreme XT/Scotchbond Multi-Purpose Plus and 93 % for CeramX Duo/XP Bond. Only ten restorations failed (5 Filtek Supreme XT and 5 CeramX Duo). Statistical analysis revealed no significant differences between the two composite-adhesive combinations with respect to color match, marginal discoloration, wear/loss of anatomical form, caries formation, marginal adaptation, and surface texture on comparing the five time periods (baseline, 1, 2, 3, and 4 years) The 4-year survival rates in the present study were favorable. The restorations exhibited excellent scores with regard to color match, marginal adaptation, surface texture, marginal discoloration, wear/loss of anatomical form, and caries formation, after 4 years of clinical evaluation. Clinical relevance An alternative clinical approach for correcting discrepancies in tooth size and form, such as performing direct composite restorations following fixed orthodontic treatment, may be an excellent and minimally invasive treatment.

Push-Out Bond Strength of Restorations with Bulk-Fill, Flow, and Conventional Resin Composites.

The aim of this study was to evaluate the bond strengths of composite restorations made with different filler amounts and resin composites that were photoactivated using a light-emitting diode (LED). Thirty bovine incisors were selected, and a conical cavity was prepared in the facial surface of each tooth. All preparations were etched with Scotchbond Etching Gel, the Adper Scotchbond Multipurpose Plus adhesive system was applied followed by photoactivation, and the cavities were filled with a single increment of Filtek Z350 XT, Filtek Z350 XT Flow, or bulk-fill X-tra fil resin composite (n = 10) followed by photoactivation. A push-out test to determine bond strength was conducted using a universal testing machine. Data (MPa) were submitted to Student's t-test at a 5% significance level. After the test, the fractured specimens were examined using an optical microscope under magnification (10x). Although all three composites demonstrated a high prevalence of adhesive failures, the bond strength values of the different resin composites photoactivated by LED showed that the X-tra fil resin composite had a lower bond strength than the Filtek Z350 XT and Filtek Z350 XT Flow resin composites.

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.

Effect of cementation protocol on push-out bond strength of fiber posts to root canal

Abstract The aim of this study was to evaluate the effect of adhesive protocol on the retention of glass-fiber posts luted into root canals. Thirty bovine incisors were endodontically treated and 9-mm-deep post holes were prepared. Fiber posts were luted using one of following protocols (n = 10): SB – Single Bond (3 M ESPE) with regular resin cement RelyX ARC (3 M ESPE); SBMP – Scotchbond Multipurpose Plus (3 M ESPE) associated with RelyX ARC; or UNI – the self-adhesive resin cement RelyX Unicem (3 M ESPE). After cementation, root/post specimens were transversally sectioned into 1-mm-thick slices, which were submitted to push-out testing in a mechanical testing machine. Bond strength data were analyzed by ANOVA (α = 0.05). There was no statistical difference between the adhesive protocols evaluated. Considering that the adhesive protocols evaluated showed similar bond strength values, simpler protocols must be preferable to lute fiber posts to root canal.

Quantitative and qualitative evaluation of resin-dentin bond strengths: in vitro effects of surface treatment with metalloproteinase inhibitors

AIM: The objective of this study was to evaluate the use of MMPs inhibitors (chlorhexidine and EDTA) in bond strength and quality of the hybrid layer of adhesive restorations in normal dentin using two ethanol-based total-etch adhesive systems. MATERIAL AND METHODS: Thirty-two extracted human molars were coronally sectioned and randomly divided into 8 groups (n=4), depending on the surface pre-treatment and adhesive system used. The total-etch adhesive systems Single Bond 2 (2-step) and Adper Scotchbond Multi-Purpose Plus (3-step) were used as follows: 1) according to manufacturer's instructions (etching with 37% phosphoric acid (H3PO4) for 15 s); 2) etching with H3PO4 for 15 s, followed by 2% chlorhexidine for 120 s; 3) etching with 0.1 M EDTA for 60 s; 4) etching with 0.1 M EDTA followed by 2% chlorhexidine for 120 s. Teeth were incrementally restored with composite resin (Filtek Z350XT). After water storage for 24 h, teeth were double-sectioned, yielding stick specimens of 1.0 mm² bonded area, and then subjected to microtensile bond strength (MTBS) test at 0.5 mm/min. Additional specimens were gold-sputtered to be analyzed under scanning electron microscopy (SEM). Data (in Mega Pascal) were subjected to Kruskal-Wallis and Dunn (p &lt;0.05) tests. RESULTS: The etching protocol (37% H3PO4 or EDTA) interfered with hybrid layer formation, monomer penetration and the MTBS. Funnel shaped resin tags were observed when dentin was etched with 37% H3PO4. In these specimens, MTBS were also higher. EDTA conditioning produced thin hybrid layers and smaller MTBS, regardless the adhesive system used. Chlorhexidine application after conditioning resulted in no apparent differences between both evaluated techniques (37% H3PO4 or EDTA). CONCLUSION: The use of chlorhexidine as a MMP inhibitor does not alter immediate bond strength values and does not interfere with hybrid layer formation.

Does the Period of Air-Drying Affect Dentin Bond Strength of Different Adhesive Systems?

Aims: To evaluate the effect of air-drying time of adhesives on shear bond strength of different adhesive systems. Methodology: The occlusal surfaces of 175 mandibular third molars were ground to obtain flat dentin surfaces and then divided into three groups according to three adhesive systems used: (1) Conventional three-step adhesive (Scotchbond Multi-purpose Plus); 2) Self-etch adhesive (Adper Easy Bond) and 3) Single bottle self-etch adhesive (Scotchbond Universal adhesive). Regarding the application of adhesives before resin composite application, it was gently air-dried for 3 s in Groups 1, whereas, the adhesive was left wet in Group 2. The group 3, that was air-dried until the liquid did not move (5 s), was served as control. Following bonding of resin cement (Filtek Supreme) to dentin, the specimens were light cured for 20s with a LED. After storage in water at 37oC for one week, the strength measurements were accomplished with universal testing machine (Lloyd LRX) until the failure occurs. Failure modes were examined using a stereomicroscope and scanning electron microscope. The data were analyzed with two-way analysis of variance Original Research Article British Journal of Medicine & Medical Research, 4(27): 4523-4532, 2014 4524 (ANOVA) and TukeyHSD tests (α=0.05). Results: The two-way ANOVA revealed that adhesive systems had a significant effect on shear bond strength values (p<0.001). However, air-drying time did not influence shear bond strength (p=0.442). Additionally, there was no interaction effect between adhesive systems and air-drying time (p=0.835). Conclusion: The data suggests that increased air-drying time of adhesives does not significantly affect bond strength.

Bonding effectiveness of two adhesive luting cements to glass fiber posts: pull-out evaluation of three different post surface conditioning methods.

The purpose of this study was to evaluate the bond strength at the post/resin-cement interface with 3 different surface treatments of glass fiber posts and with 2 different luting resin cements. Sixty glass fiber posts (RelyX Fiber Post) were randomly divided into 3 groups (n = 20) and were luted with a dual-polymerizing self-adhesive universal resin cement (RelyX Unicem) and with a dual-polymerizing resin cement (RelyX ARC). This was carried out in association with a dual-polymerizing adhesive (Scotchbond Multi-Purpose Plus) in simulated plexiglass root canals after receiving three different pretreatment procedures. A pull-out test was performed on each sample to measure bond strengths. Data were analyzed with two-way ANOVA. Two samples from each group were processed for SEM observations in order to investigate the morphologic aspect of the post/cement interface. Both resin cements demonstrated significant different bond strength values (P < 0.0001). The surface treatment result was also statistically significant (P = 0.0465). SEM examination showed a modification of the post surface after pretreatment with methyl methacrylate. The dual-polymerizing self-adhesive universal resin cement achieved higher MPa bond strength values. The use of methyl methacrylate as a surface treatment of glass fiber posts provided a significant increase in bond strengths between the posts and both luting materials.