Significant Differences In Bond Strength Research Articles

Bond strength efficiency of a high fluoride and calcium release self-adhesive resin cement: A comparative in vitro study

Aim: To clarify the bond strength of Theracem in comparison to other types of adhesive material, in addition to testing the adhesive remnant index (ARI). Material and Methods: A hundred extracted human premolars were collected for orthodontic purposes. Teeth were stored in 1% Chloramine-T trihydrate as bacteriostatic/bactericidal solution for one week; then, they were transmitted into distilled water. The buccal surface of the studied teeth was kept under surveillance and mounted in acrylic block. Siamese metal pre-adjusted premolar brackets were fixed on the buccal surface using three adhesive cements: Bisco ORTHO, GC Fuji ORTHO LC (Light Cure) and Theracem. The teeth were randomly divided into five groups of 20 specimens each. Group 1 (G1) used 37% phosphoric acid gel, Bisco primer, and Bisco adhesive. Group 2 (G2) used GC Fuji ORTHO LC (Light Cure) without etching. Group 3 (G3) used GC Fuji ORTHO LC (Light Cure) with etching. Group 4 (G4) used Theracem without etching. Group 5 (G5) used Theracem with etching. All the tested specimens were kept at 370°C in a distilled water bath for 24 h. Shear bond strength (SBS) was conducted using a universal microcomputer-controlled electronic test machine. Then, specimens’ surfaces were assessed under a stereomicroscope with a 10× magnification to examine the orthodontics adhesive residue’s buccal surface and scored using ARI. Results: The G4 exhibited the lowest mean bond strength value (M = 11.24, SD = 3.52), whereas G3 yielded the highest bond strength value (M = 25.02, SD = 3.41). The variance analysis revealed F = 61.71, indicating a significant difference among the bond strength values (P < .001). Tukey HSD post hoc testing demonstrated a significant difference in bond strength among groups, except G2 with G1 and G3. Kruskal–Wallis test showed statistically significant differences among all groups (P < .001). On comparison, the least adhesives that remained on the tooth surface were in G4 and G5. Conclusion: Theracem bonding system provides many advantages, as there is no need for an acid-etching step, it is easy to manipulate, and it provides a very suitable S.B.S. with no enamel detachment during debonding. Also, scores 0 and 1 in the ARI test lead to a decrease in enamel damage.

Effect of Over-Etching and Prolonged Application Time of a Universal Adhesive on Dentin Bond Strength.

This study investigated the effect of over-etching and prolonged application time of a universal adhesive on dentin bond strength. Ninety extracted human molars were ground to dentin and randomly allocated into nine groups (G1–9; n = 10 per group), according to the following acid etching and adhesive application times. In the control group (G1), phosphoric acid etching was performed for 15 s followed by application of the universal adhesive Scotchbond Universal (3M) for 20 s, as per manufacturer’s instructions. In groups G2–5, both the etching and adhesive application times were either halved, doubled, quadrupled, or increased eightfold. In groups G6–9, etching times remained the same as in G2–5 (7.5 s, 30 s, 60 s, and 120 s, respectively), but the adhesive application time was set at 20 s as in the control group (G1). Specimens were then restored with a nanofilled composite material and subjected to microtensile bond strength testing. Bond strength data were statistically analyzed by ANOVA and Tukey’s post-hoc tests (α = 0.05). The relationship of bond strength with etching and adhesive application time was examined using linear regression analysis. Treatment of dentin with halved phosphoric acid etching and adhesive application times (G2) resulted in a significant bond strength decrease compared to the control group (G1) and all other test groups, including the group with halved acid etching, but 20 s of adhesive application time (G6). No significant differences in bond strength were found for groups with multiplied etching times and an adhesive application time of 20 s or more, when compared to the control group (G1). In conclusion, a universal adhesive application time of at least 20 s is recommended when bonding to over-etched dentin.

Effect of surface treatment of CAD/CAM resin composites on the shear bond strength of self-adhesive resin cement.

This study examined the effects of sandblasting, hydrofluoric acid etching and priming on the shear bond strength of self-adhesive resin cement between seven different CAD/CAM resin composites and a resin composite core material at 24-h after cement mixing. Five surface treatments [control (C), sandblasting (S), priming (P), sandblasting with priming (SP), and 9% HF etching with priming (HFP)] were performed respectively for disc specimens of CAD/CAM blocks. There were no significant differences in bond strength among the C, S, and P, except for one block (p>0.05). SP showed a greater bond strength than S. Weibull moduli were not changed significantly among all treatments for all blocks, whereas the strengths with 5% and 95% failure probability of SP and HFP showed greater values than the others. The bond strengths of HFP were comparable to those of SP. Priming after sandblasting or HF etching could be effective to increase the bond strength of CAD/CAM blocks.

Evaluation of Surface Preparations Combined With Different Generations of Bonding on the Bond Strength of Resin Composite Repair: An Original Article

Background: This study evaluated the effect of different mechanical surface preparation methods, as well as different adhesives including universal bonding agents, on the shear bond strength of composite repairs. Methods: This study was experimentally performed on 64 Z250 composite discs (3M, ESPE) with 6 mm diameter and 2 mm height. A total of 60 samples were randomly divided into 6 groups as follows: Group A) diamond milling + Adper Single Bond 2, group B) diamond milling + Single Bond Universal, group C) diamond milling + All Bond Universal, group D) sandblast + Adper Single Bond 2, group E) sandblast + Single Bond Universal, group F) sandblast + All Bond Universal. Then, the new composite was placed on the bonding layer, cured, and underwent aging again. The samples were assessed for shear bond strength by universal testing machine and their failure mode was investigated under the light microscope (20x and 100x). Finally, 4 remaining samples, which were surface-prepared by diamond milling and sandblasting, were evaluated for qualitative analysis of surface roughness using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed by oneway ANOVA and Fisher’s exact tests. Results: There was no statistically significant difference in shear bond strength and failure mode among the groups (P> 0.05). However, diamond milling + Single Bond Universal group showed the highest and Adper Single Bond 2 had the lowest bond strength. Conclusions: There was no significant difference in bond strength using different methods. Therefore, diamond milling + Single Bond Universal was suggested as the best and most available method compared to sandblasting.

Shear Bond Strength of Three Composite Resins to Fluorosed and Sound Dentine: In Vitro Study.

Introduction This in vitro study compared the shear strength of three composite resin systems to fluorosed and normal dentin. Methods Silorane FiltekTM P90, FiltekTMZ250 XT in combination with the adhesive system AdperTM Single bond 2, and Amelogen® Plus in association with Peak Universal Bond® were tested. Fifteen normal and 15 fluorosed dentine disks were prepared per material. The shear bond strength test was performed using a universal machine. Results One-way ANOVA revealed significant differences in bond strength between the tested composite resins. All tested materials had significantly different adhesion at the fluorosed and the nonfluorosed interface. FiltekTM Z250 XT and Silorane had lower adhesion values to fluorosed than to normal dentin. In contrast, Amelogen® Plus presented a better average resistance at the fluorosed interface. Conclusion Amelogen® Plus presented a better average shear bond strength on the fluorosed dentine. FiltekTMZ250 XT showed the best adhesion forces and shear bond strength with sound dentine. Further studies are needed to better understand the sealing of these systems.

Effect of reduced airborne-particle abrasion pressure on the retention of zirconia copings resin bonded to titanium abutments

Statement of problemThe optimal conditioning of zirconia is essential for a durable bond between zirconia copings and titanium inserts in 2-piece dental implant abutments. Low-pressure activation of the zirconia surface may be adequate for retention. PurposeThe purpose of this in vitro study was to evaluate the influence of airborne-particle abrasion (APA) of the zirconia surface with different pressures on the retention of zirconia copings bonded to titanium abutments. In addition, 2 luting systems were compared. Material and methodsComputer-aided design and computer-aided manufacturing (CAD-CAM) zirconia copings were divided into 3 groups (n=32): 0.1 MPa, 0.25 MPa, and not airborne-particle abraded surfaces with 50-μm alumina (Al2O3) particles. Compatible titanium abutments were airborne-particle abraded at a pressure of 0.25 MPa. All specimens were ultrasonically cleaned before bonding. Each group was divided into 2 subgroups (n=16) with different luting composite resins. A 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) containing self-adhesive luting composite resin (Panavia SA Cement Plus) and a conventional luting composite resin (Multilink Hybrid Abutment) in combination with a 10-MDP–containing universal primer (Monobond Plus) was compared. Two storage conditions were tested: in water (37 °C) for 3 days or 150 days with 37 500 thermocycles between 5 °C and 55 °C. After artificial aging, retention was measured in tension, and the failure modes were analyzed by using a light microscope and a scanning electron microscope. Statistical analysis was performed with 1-way ANOVA and the Games-Howell test for post hoc analysis (α=.05). ResultsThe mean retention of the airborne-particle abraded groups ranged from 576.0 N to 1049.3 N after 150 days of water storage and 37 500 thermocycles. No significant difference in bond strength was found between the 2 luting composite resin groups with airborne-particle abraded zirconia surfaces after 150 days (P<.05). Both bonding systems provided durable bond strength after 3 and 150 days. Failure mode was mainly cohesive at the titanium surfaces and predominantly adhesive at the zirconia surfaces. The retention was significantly higher if APA was used versus no APA (P<.05), while the APA pressure used made no significant difference. ConclusionsThe APA of zirconia copings at a pressure of 0.1 MPa in combination with 10-MDP–containing luting composite resins and primers is adequate for the durable bonding of zirconia copings to titanium inserts.

Influence of cleaning methods on the bond strength of resin cement to saliva-contaminated lithium disilicate ceramic.

The aim of the present study was to examine the influence of different cleaning methods on the bond strength of resin cement to saliva-contaminated lithium disilicate ceramic. Lithium disilicate ceramic specimens (n = 8/group) were etched with 5% hydrofluoric acid (HF) to comprise the control group. After or before saliva contamination, specimens were cleaned with one of five methods: rinsing with water-spray (WS), K etchant GEL (PA), Ivoclean (IC), AD Gel (ADG), or application of a silane coupling agent before immersion in saliva (SCA). Stainless steel rods were bonded to the ceramic with resin cement. The tensile bond strength was measured after 24h (TC0) and after thermal cycling at 4-60°C (TC20000). Specimen surfaces were also evaluated using X-ray photoelectron spectroscopy. Data were statistically analyzed using two-way ANOVA and Tukey tests (α = 0.05). Both the cleaning method (p = 0.0001) and storage condition (p = 0.0001) significantly affected the bond strength results. Before or after TCs, no significant differences in bond strength were observed between the control group and the other cleaning groups except for the WS group, which had a significantly lower bond strength than did the PA, IC, ADG, or SCA groups (p < 0.05). The level of nitrogen in the ADG group was almost equal to that in the control group. WS cleaning did not restore the bond strength of resin cement to saliva-contaminated lithium disilicate ceramic etched with HF, while PA, IC, ADG, and SCA all benefited. Lithium disilicate ceramic restorations etched with HF should to be cleaned with ADG after saliva contamination.

Effect of calcium hydroxide intracanal medicament on the push-out bond strength of RelyX Unicem self-adhesive cement

Aim: This study was aimed to determine the use of calcium hydroxide (Ca(OH)2) intracanal medicament effect on the push-out bond strength of RelyX Unicem self-adhesive cement onto the root canal wall. Materials and Methods: A total of 50 extracted human maxillary permanent incisor teeth were randomly divided into control and experimental groups (n = 25 for each group). The control group was prepared for routine root canal treatment followed by post space preparation. RelyX Unicem self-adhesive cement is used for the cementation of fiber post in the root canal, as in experimental group, Ca(OH)2intracanal dressing was placed into the root canal for a week, followed by root canal filling, post space preparation, and cementation of fiber post using RelyX Unicem cementation. Each sample was divided into coronal, middle, and apical root sites. They were horizontally sliced and examined using scanning electron microscope (SEM). Three slices from each of the three sites were subjected to push-out test for bond strength measurement. Independent t-test was used to compare the push-out bond strength of RelyX Unicem on the root canal wall. One-way analysis of variance and pairwise comparison test were used for the statistical analysis. The significant level was set as P Results: The significant differences in bond strength were demonstrated between the different sites of the root, where the coronal and apical with the P value 0.031 and 0.020, respectively. However, the middle third of the root showed no statistically significant difference, where P = 0.072. Conclusions: Intermediate Ca(OH)2dressing has an effect on the bond strength of RelyX Unicem self-adhesive resin cementation on the root canal wall.

Resin adjustment of three-dimensional printed thermoset occlusal splints: Bonding properties – Short communication

ObjectivesTo evaluate the interfacial adhesion of an autopolymerizing acrylic resin to 3D printed thermoset occlusal splints compared to thermoplastic occlusal splints. Materials and methodsCylinders made of an autopolymerizing acrylic resin were adhered to 3D printed thermoset and also to thermoplastic plates. A different surface treatment and three storage conditions were used: dry, 7 days water-storage and 14 days water-storage. Bond strength test (so-called shear-bond strength test) was afterward performed. ResultsANOVA (R2 = 0.764) revealed significant differences in bond strength according to material (p < 0.001) and storage (p < 0.001) but not for surface treatment (p = 0.202). ConclusionsThe bond strength of autopolymerizing acrylic resin to 3D printed thermoset plates is higher when compared to thermoplastic plates. Bonding between acrylic resin and 3D printed splints was high enough for clinical applications.conclusion Clinical relevanceThe bond strength values obtained in this study with 3D printed plates were at the level of generally accepted adequate bonding values for prosthetic materials.

Bond strength of orthodontic adhesives to dry and saliva-moistened enamel – a comparative in vitro study

salivamoistened enamel. Design/methodology/approach: One hundred twenty stainless steel brackets were bonded to human mandibular third molars with six materials: Enlight LC® (Ormco Corp), Grengloo® (Ormco Corp), Light Bond® (Reliance Orthodontic Products), Charisma® (Heraeus Kulzer), SmartBond® (Gestenco), and Transbond XT® with MIP® primer (3M Unitek). One half of the specimens in each group (n=10) was bonded to dry enamel, while the other half to saliva-moistened enamel. Bond strength testing was performed with a wire loop loading technique after 30-min incubation in artificial saliva. Failure mode was evaluated using adhesive remaining index (ARI). Findings: No significant differences in bond strength to dry enamel were noted for all composite materials (p&gt;0.05). SmartBond exhibited significantly greater bond strength to moistened enamel (7.10 ± 1.47 MPa) and comparable with other composite materials to dry enamel. Composite materials demonstrated significantly reduced bond strength to saliva-moistened enamel (p&lt;0.001), except for Transbond MIP, whose bond strength was not significantly decreased by saliva contamination (p=0.089). There was not statistically significant difference between bond strength of SmartBond and Transbond to saliva contaminated enamel. A higher incidence of cohesive failures was noted for all materials. Research limitations/implications: Composite light-cured materials provide adequate bond strength to dry enamel. Cyanoacrylate adhesive provides sufficient bond strength only under moist conditions. Transbond XT+MIP has sufficient bond strength to either dry or saliva-moistened enamel. Practical implications: The study evaluated the bonding strength of orthodontic brackets, which is a critical parameter in orthodontics, especially in situations that do not allow for proper isolation from saliva, such as bonding to impacted teeth following surgical exposure. Originality/value: Bond strengths evaluated with loop loading technique in different study environments would help the orthodontist to choose the most effective adhesive for the specific clinical situation.

Gradual dehydration affects the mechanical properties and bonding outcome of adhesives to dentin.

This study evaluated the effects of dehydration on the mechanical properties of adhesive resins and dentin, and on the microtensile bond strength (µTBS) of adhesives. Third molars were randomly bonded with Clearfil Mega Bond (MB) or Clearfil SE Bond 2 (SE). After water-storage (37°C; 24 h), µTBS was obtained in 'wet' (tested after 5 min of removal from storage) and 'dehydrated' (tested after 10, 15 min and 24 h) conditions by a universal tester (crosshead speed: 1 mm/min). Data were analyzed by two-way ANOVA and Duncan's test. Hardness (H), Elastic modulus (E) and weight-loss of dentin beams and adhesive-resin discs were also monitored over time and analyzed by one-way repeated measures ANOVA and Bonferroni's test (α=0.05). Significant differences in bond strength were observed for adhesives and for conditions. Except for dentin's E, dehydration caused significant gradual changes in the H, E and weight of adhesive resins and dentin (p<0.05).

Effect of Bonding and Rebonding on the Shear Bond Strength of Two-Piece Implant Restorations.

To evaluate the rebonding strength of ceramics to titanium alloy after disassembling by heat treatment. A total of 40 titanium alloy (titanium-6 aluminum-4 vanadium) disks (4.0 × 6.6 mm) and 20 zirconia (Lava Plus) disks were manufactured using computer-aided design and computer-aided manufacturing (CAD/CAM) technology. Twenty heat-pressed lithium disilicate glass-ceramic (IPS e.max Press LT) disks were fabricated and used as controls. Bonding protocol for each specimen surface was performed according to manufacturer's instructions. Specimens (n = 10) of zirconia/titanium alloy (ZR) and lithium disilicate/titanium alloy (LD) were bonded using adhesive resin cement (RelyX Ultimate) and then subjected to a heat treatment (HT, 320°C, 2 minutes) to disassemble the bonding complex, cleaned with aluminum oxide airborne-particle abrasion, and rebonded following the initial protocol, group ZRHT and group LDHT, respectively. After 5000 cycles of thermal cycling, a shear bond test was conducted. A universal testing machine was used at a 5 mm/min crosshead speed. Failed specimens were examined with stereomicroscopy at 10× magnification to identify the mode of failure. One-way ANOVA and Tukey HSD tests were applied for statistical analysis of the shear bond strength data, with statistical significance at α = 0.05. The mean ± SD bond strength values ranged from 28.3 ± 7.2 to 45.9 ± 9.7 MPa. Statistically significant lower shear bond strength values were obtained from the LD group (p = 0.002, F = 5.89), while no statistically significant differences in bond strength were observed between the ZR and ZRHT groups (p > 0.05). Failure mode was predominantly mixed-type failure pattern for all specimens. Heat and abrasion surface treatment increased the bond strength of lithium disilicate glass-ceramics cemented to titanium alloy, but no effect was observed on zirconia/titanium alloy bonding.

Comparative evaluation of effects of natural antioxidants on the shear bond strength of composite resin to bleached enamel.

The use of antioxidants immediately after bleaching showed increased bond strength. This study aimed to compare the effects of natural antioxidants on the shear bond strength of composite resin to bleached enamel. Fifty extracted single-rooted upper incisors were decoronated by sectioning the roots 2 mm below the cementoenamel junction, and then, crowns were embedded in autopolymerizing acrylic resin block (3.0 cm × 3.0 cm × 3.0 cm) with the labial surface exposed. They were randomly divided into five groups, depending on the type of antioxidant used (n = 10): (i) Group 1: control (no bleaching), (ii) Group 2: bleaching only, (iii) Group 3: bleaching + 10% sodium ascorbate (antioxidant), (iv) Group 4: bleaching + green tea, and (v) Group 5: bleaching + white tea. Labial surfaces of 40 teeth were bleached with 38% hydrogen peroxide for 20 min following manufacturer's instructions. After that, the experimental groups (Groups 3, 4, and 5) were treated with respective antioxidant solutions before composite restorations were done using a cylindrical plastic mold (3 mm × 5 mm). Shear bond strength of the specimens was tested under universal testing machine. Data were analyzed with ANOVA and Tukey's post hoc test. There were statistically significant differences between shear bond strength of control groups (Groups 1 and 2) and experimental groups (P < 0.05), but no significant difference in bond strength was observed among the antioxidants used. Application of antioxidants immediately after bleaching showed increased bond strength. Green tea and white tea extract can be used as alternative antioxidants in improving the bond strength of enamel.

Evaluation of the effect of chlorhexidine and sodium hypochlorite in adhesive cementation of fiber posts - in vitro study

Abstract Introduction The attachment of fiberglass posts is achieved through an adhesive process. Failures in adhesion may occur due to the hydrolytic degradation of the adhesives, or to the degradation of the collagen fibres of the hybrid layer by intrinsic enzymes. Objective To evaluate the effect of chlorhexidine and sodium hypochlorite treatment on bond strength to dentin. Material and method Thirty bovine roots were randomly distributed into 3 groups (n=10): a) Control, b) 2% Chlorhexidine, and c) 5% Sodium Hypochlorite. Next, RelyX® ARC resin cement was used to cement the post. Each specimen resulted in samples from the three root thirds that were submitted to the pushout test (MPa) at 24 hours and 12 months. Bond strength values were analysed using the Kolmogorov-Smirnov, 3-way ANOVA and Tukey tests. The fracture mode of the pin was also analysed using stereomicroscopy. Result There were no significant differences between treatments at the immediate time (p=0.0644) or in the interaction of factors (p=0.1935). After one year, the experimental groups showed no significant differences in bond strength in relation to the control group, with the exception of the cervical third of the chlorohexidine group in which there was a significant loss of adhesion. As for the fracture mode, there was a predominance of the mixed type in all groups and thirds. Conclusion The use of chlorhexidine or hypochlorite provides neither benefits nor losses in the adhesive bond strength of fiberglass posts. However, there is an influence of the root thirds, with the worst bond strength in the apical third.

Evaluation of Effect of Dietary Solvents on Bond Strength of Compomer, Ormocer, Nanocomposite and Activa Bioactive Restorative Materials.

Objectives:The successful endodontic therapy is judged by ability of tooth to withstand masticatory forces. The present study focused on comparing the strength of restorative materials, i.e., compomer, ormocer, nanocomposite, and ACTIVA Bioactive after conditioning in dietary solvents.Materials and Methods:This in vitro study consisted of 26 specimens of each restorative material Compomer (F2000 3M ESPE), Nanocomposite (Filtek Z350XT), Ormocer (Admira VOCO), and ACTIVA Bioactive (Pulpdent). The I-shear–punch test was conducted with the help of custom-designed shear–punch apparatus in Universal Testing Machine in different dietary solvents. Results were statistically analyzed using IBM SPSS Statistics for Windows, Version 20.0. (IBM Corp., Armonk, NY) and using Tukey’s test and one-way analysis of variance test at P < 0.5.Results:Ormocer conditioned in heptanes had the highest mean shear–punch strength. ACTIVA Bioactive conditioned in distilled water showed the highest mean shear–punch strength. There was a significant difference in bond strength among all restorative materials (P < 0.05).Conclusion:Ormocer conditioned in heptane had significantly higher shear strength. ACTIVA Bioactive conditioned in distilled water had significantly increased shear strength. The nanofilled composite was significantly stronger than the Ormocer, ACTIVA Bioactive, and Compomer – a polyacid-modified composite.

Effect of Er:YAG and Burs on Coronal Dentin Bond Strength Stability.

To evaluate the immediate and aged bond strength and interfacial nanolaekage of different adhesives and protocols on dental elements prepared with diamond burs and Er:YAG laser. Forty molar crowns were flattened and a standardized smear layer was created. Teeth were divided into two main groups according to the dentin cutting technique: 1. Er:YAG laser for 30 s at 30 Hz repetition rate, 250 mJ energy per pulse, and water spray irrigation set at level 8; and 2. diamond bur. Each group was then divided into subgroups according to the adhesive protocol: SG1: dentin etching for 15 s followed by universal adhesive application (All Bond Universal, Bisco); SG2: universal adhesive application (All Bond Universal); SG3: two-step self-etch adhesive application (Clearfil SE Bond 2, Kuraray Noritake); SG4: etching followed by 3-step etch-and-rinse adhesive application (Optibond FL, Kerr). After curing the adhesives, resin composite buildups of 4 mm were made and specimens were sectioned to obtain 1-mm-thick sticks in accordance with the μTBS test technique. Sticks were stressed to failure at baseline and after 6 months of storage in artificial saliva. Three teeth per group were prepared for nanoleakage interfacial analyses. Data were statistically analyzed with three-way ANOVA and Tukey's post-hoc test (p < 0.05). A significant difference in bond strengths was found for treatment, aging, and adhesive protocol. Nanoleakage analysis showed higher marginal infiltration in Er:YAG-treated groups both at baseline and after aging. Surfaces prepared with diamond burs presented higher bond strengths than did those prepared with Er:YAG laser. Adhesive protocols and aging could influence the adhesive-dentin interface. Further studies are necessary to validate the results obtained.

Bonding of glass ceramic and indirect composite to non-aged and aged resin composite.

Since adhesion of the restorative materials to pre-polymerized or aged resin composites presents a challenge to the clinicians, existing restorations are often removed and remade prior to cementation of fixed dental prostheses (FDPs). This study evaluated bond strength of non-aged and aged resin composite to an indirect resin composite and pressed glass ceramic using two resin cements. Disk-shaped specimens (diameter: 3.5, thickness: 3 mm) (N = 160) produced from a microhybrid resin composite (Quadrant Anterior Shine) were randomly divided into eight groups. While half of the specimens were kept dry at 37°C for 24 h, the other half was aged by means of thermocycling (6000 times, 5°C to 55°C). The non-aged and aged resin composites were bonded to a highly filled indirect composite (Estenia) and a pressed glass ceramic (IPS Empress II) using either a photopolymerizing (Variolink Veneer) or a dual-polymerizing (Panavia F2.0) resin cement. While cementation surfaces of both the direct and indirect composite materials were silica coated (30 µm SiO2, CoJet-Sand) and silanized (ESPE-Sil), ceramic surfaces were conditioned with hydrofluoric acid (20 s), neutralized, and silanized prior to cementation. All specimens were cemented under a load of 750 g. Shear force was applied to the adhesive interface in a universal testing machine (1 mm/min). Failure types of the specimens were identified after debonding. Significant effects of aging (p < 0.05), restorative material (p < 0.05), and cement type (p < 0.05) were observed on the bond strength (3-way ANOVA). Interaction terms were also significant (p < 0.05) (Tukey's test). After aging, in terms of bond strength, indirect composite and pressed glass ceramic in combination with both cements showed no significant difference (p > 0.05). Both indirect composite (24.3 ± 5.1 MPa) and glass ceramic in combination with Variolink (22 ± 9 MPa) showed the highest results on non-aged composites, but were not significantly different from one another (p > 0.05). On the aged composites, indirect composite and glass ceramic showed no significant difference in bond strength within each material group (p > 0.05), with both Panavia (17.2 ± 6 and 15 ± 5.5 MPa, respectively) and Variolink (19 ± 8, 12.8 ± 5.3 MPa, respectively), but in all groups, glass ceramic-Variolink on aged composite revealed the lowest results (12.8 ± 5.3 MPa). Among all groups, predominantly cohesive failures were observed in the indirect resin composite substrate (79 out of 80) as opposed to the ceramic (18 out of 80) (p < 0.05) (Chi square). Regardless of the resin cement type, considering the bond values and the failure types, the adhesion quality of indirect composite cemented to non-aged and aged resin composite was superior with both cements compared to that of pressed glass ceramic.

Oval Versus Circular-Shaped Root Canals: Bond Strength Reached with Varying Post Techniques.

The aim of this study was to compare the bond strength (BS) of glass fiber posts (GFP) luted to oval and circular-shaped root canals rehabilitated using varying post techniques, at different intraradicular levels. Ninety 16-mm-long roots of human mandibular premolars, classified either as having oval or circular-shaped canals, were endodontically treated and prepared for restoration using one of three different post techniques (n=15): 1) single GFP; 2) resin-relined GFP; 3) main GFP associated with accessory posts. GFPs were luted with a dual polymerizing resin cement (RelyX ARC) after the canal had been treated with a 3-step etch-and-rinse adhesive system (Adper Scothbond Multipurpose). The samples were sectioned into three 1-mm-thick sections, which were differentiated by the root level (cervical, middle and apical) and tested for push-out BS. Assessment of failure mode was made under a stereomicroscope. Data were analyzed using repeated measures three-way ANOVA and Tukey's test. The root canal cross-section had a significant influence on BS (p<0.001), with the lowest values being observed in oval-shaped canals. The post technique also significantly affected the BS (p=0.018), with the resin-relined GFPs providing the highest BS values in both oval and circular-shaped canals. Irrespective of the cross-section of the root canal and post technique, there was no significant difference in BS in the cervical, middle and apical third of the root canal (p=0.084). In oval-shaped canals, the BS to intraradicular dentin at cervical, middle or apical level could be increased when the GFPs posts were relined.

Evaluation of the bond strength and characteristics of zirconia after different surface treatments

Statement of problemNonthermal plasma treatment could increase the bond strength of resin cements to zirconia, but studies are lacking. PurposeThe purpose of this in vitro study was to evaluate zirconia bond strength, surface roughness, and contact angle and to measure the infrared spectrum after different surface treatments. Material and methodsYttria-stabilized tetragonal zirconia polycrystal (Y-TZP; n=9) blocks were sectioned into 36 slices (12×11×3 mm) and divided (n=4) into surface treatment groups as follows: 2 control groups, consisting of airborne-particle abrasion plus primer (APP) and 10% hydrofluoric acid etching plus primer (HFP), and 3 experimental groups consisting of a nonthermal plasma (NP) application; a nonthermal plasma plus primer application (NPP); and a 10% hydrofluoric acid etching plus nonthermal plasma plus primer (HFNPP) application. Each zirconia disk was cemented to a prepolymerized resin block. After cementation, the specimens were sectioned for microtensile strength testing and for surface roughness analysis and contact angle analysis. Results were submitted to analysis of variance and Tukey tests (α=.05). ResultsResults showed no statistically significant differences between the APP and HFNPP groups, but these 2 groups showed statistically better bonding than those of HFP, NP, and NPP. ConclusionsAirborne-particle abrasion resulted in a significant increase in surface roughness compared with the other groups. After nonthermal plasma treatment, the contact angle of the zirconia surface decreased within 48 hours. Nonthermal plasma application for surface treatment of zirconia showed no significant difference in bond strength when compared with airborne-particle abrasion.

Phosphoric and carboxylic methacrylate esters as bonding agents in self-adhesive resin cements.

The aim of the present study was to investigate the effect of pH and phosphoric ester structure (phosphonate or phosphate) on the bond strength of different dental restorative materials. The following three self-adhesive resin cements were used in the present study: RelyX™ Unicem, Maxcem and Multilink Sprint The pH of each cement was measured using a pH meter. The cements were used to attach a variety of restorative materials to human dentin and the bond strength was measured by assessing shear strength using a universal testing machine. The pH values of RelyX Unicem, Maxcem and Multilink Sprint were 3.78, 1.78 and 3.42, respectively. Maxcem, a phosphate-based self-adhesive cement, was demonstrated to form the weakest bonds. No significant difference in bond strength was observed between RelyX Unicem and Multilink Sprint, which are phosphonate-based cements. The results of the present study suggest that the chemical structure of the functional monomer influences the performance of an adhesive material. Furthermore, the pH of acidic functional monomers containing phosphonate or phosphate groups has an effect on the strength of bonds formed between dentin and restorative materials.