Showing papers in "Journal of Adhesive Dentistry in 2013"

Randomized clinical trial of indirect resin composite and ceramic veneers: up to 3-year follow-up.

Abstract: PURPOSE: This randomized controlled split-mouth clinical trial evaluated the short-term survival rate of indirect resin composite and ceramic laminate veneers. MATERIALS AND METHODS: A total of 10 patients (mean age: 48.6 years) received 46 indirect resin composite (Estenia; n = 23) and ceramic laminate veneers (IPS Empress Esthetic; n = 23) on the maxillary anterior teeth. Veneer preparations with incisal overlap were performed and existing resin composite restorations of good quality were not removed but conditioned using silica coating (CoJet) and silanization (ESPE-Sil). Enamel and dentin were etched and rinsed; adhesive resin (ExciTE) was then applied. After cementation (Variolink Veneer), restorations were evaluated at baseline and thereafter every 6 months for up to 3 years using modified USPHS criteria. RESULTS: Seventeen laminate veneers were bonded onto intact teeth and 29 on teeth having existing resin composite restorations. In total, 3 failures were observed in the form of debonding (n = 1) and fracture (n = 2) in the group of resin composite laminate veneers. No significant difference was observed between the survival rates of composite and ceramic laminate veneers (Estenia: 87%, IPS Empress Esthetic: 100%; p > 0.05). The overall survival rate was 93.5% (Kaplan-Meier). Of the 43 laminate veneers, minor voids and defects were observed in 6 of the composite and 3 of the ceramic veneers. Slight staining at the margins (n = 3) and slightly rough surfaces were more frequently observed for the resin composite laminate veneers (n = 18) up to the final recall. CONCLUSION: Early findings of this clinical trial on two veneer materials showed statistically similar survival rates. Surface quality changes were more frequent in the composite veneer material.

Polymerization shrinkage stresses in a premolar restored with different composite resins and different incremental techniques.

Abstract: Purpose To investigate how the incremental filling technique, elastic modulus, and post-gel shrinkage of different dental composite resins affect residual shrinkage stress in a restored premolar. Materials and methods Sixteen composites indicated for restoring posterior teeth were tested. Elastic modulus and Knoop hardness were measured using Knoop indentation tests (n = 10). A strain gauge test was used to measure the post-gel shrinkage (n = 10). Two incremental techniques, horizontal or oblique, were applied in a finite element model of a premolar in combination with the experimentally determined properties to assess the stress conditions along the interface of the restoration and within the material structures. Linear regressions were determined between residual shrinkage stress and the elastic modulus and post-gel shrinkage values. Results The mechanical properties and the post-gel shrinkage varied significantly among the composites tested. The calculated shrinkage stress showed a strong correlation with post-gel shrinkage and a weaker correlation with elastic modulus. The oblique incremental filling technique resulted in lower residual shrinkage stress in the enamel and dentin and along the enamel/composite interface compared to the horizontal technique. Conclusion Residual stress varied significantly among the contemporary dental composites indicated for restoring posterior teeth. Shrinkage stress in a restored tooth correlated with post-gel shrinkage. In general, oblique incremental filling resulted in lower residual stresses than did horizontal increments.

Chlorhexidine application in adhesive procedures: a meta-regression analysis.

Abstract: Purpose To evaluate the association between chlorhexidine application and the bond strength of an adhesive system to dentin and to assess the association among eight other variables. Materials and methods Laboratory studies evaluating the use of chlorhexidine on dentin that verified the immediate and longitudinal bond strength were included. The terms were selected according to the Medical Subject Headings (MeSH) for PubMed and adapted for the other databases accordingly. Systematic searches were conducted in 3 electronic databases in December 2010: PubMed, EMBASE, and LILACS. Languages were limited to English, Spanish, and Portuguese. Results All longitudinal bond strength studies were analyzed in accordance with the inclusion/exclusion criteria, totaling 16 articles. A meta-regression analysis was performed with articles containing complete mean bond strength data (n = 14 articles). Conclusion Our results showed that the association between the concentration of chlorhexidine and the bond strength is, apparently, not linear. Therefore, future large-scale studies should be developed to investigate the association between the chlorhexidine concentration and hybrid layer preservation.

Potential smear layer interference with bonding of self-etching adhesives to dentin.

Abstract: PURPOSE To evaluate the effect of smear-layer interposition on the bonding effectiveness of self-etching adhesives with different etching potential. MATERIALS AND METHODS Bur-cut dentin specimens were obtained from 25 human molars after preparation of the dentin surface with a medium-grit diamond bur (bur-cut). An additional 25 molars were fractured at the midcoronal dentin to create a smear-layer-free surface (smear-free dentin). The prepared teeth were assigned to 5 groups, according to the adhesive to be applied: a strong one-step self-etching adhesive (PLP, Adper Prompt L-Pop, 3M ESPE, pH = 0.8); two ultra-mild one-step self-etching adhesives (C3S, Clearfil Tri-S Bond, Kuraray, pH = 2.7; AEB, Adper Easy Bond, 3M ESPE; pH = 2.7 ); as the self-etching control, a mild two-step self-etching adhesive (CSE, Clearfil SE Bond, Kuraray, pH of primer = 1.9); and as the etch-and-rinse control, a three-step etch-and-rinse adhesive (OFL, Optibond FL, Kerr). After composite buildups were made, all specimens were stored in distilled water (24 h/37°C) prior to microtensile bond strength testing (µTBS). The failure mode was determined with a stereomicroscope at 50X magnification. Representative µTBS specimens were processed for analysis in a Feg-SEM. The Kruskal-Wallis test was performed to determine statistical differences (p < 0.05). RESULTS Except for the strong one-step self-etching adhesive, all other self-etching adhesives (mild and ultramild) revealed a significantly lower bond strength to bur-cut dentin than to smear-free dentin. The etch-and-rinse adhesive presented the highest µTBS, which was not significantly different when bonded to bur-cut or smear-free dentin. Fracture analysis demonstrated a prevalence of adhesive failures for the self-etching adhesives, while OFL revealed more mixed failures. SEM revealed that smear debris remained part of the adhesive interfacial complex produced by the ultra-mild one-step self-etching adhesive C3S when applied on bur-cut dentin. CONCLUSION Smear debris interferes with the interaction of mild and ultra-mild self-etching adhesives with dentin.

Effect of the flavonoid epigallocatechin-3-gallate on resin-dentin bond strength.

Abstract: Purpose To evaluate the effect of dentin pretreatment with epigallocatechin-3-gallate solution on the preservation of the resin/dentin interface with etch-and-rinse adhesives. Materials and methods Thirty extracted human molars were prepared to expose the dentin surface and divided into 5 groups according to the pretreatment solution. Dentin surfaces were etched (35% phosphoric acid for 15 s), rinsed, and air dried. Dentin was rewetted either with distilled water, 3 different epigallocatechin-3-gallate solutions (EGCG; 0.02%, 0.1%, or 0.5% w/v), or 2% chlorhexidine digluconate solution for 60 s. Adper Single Bond 2 was applied and a subsequent 5-mm-thick resin crown was built up. Bonded teeth were longitudinally sectioned to obtain sticks with a cross-sectional area of 1.0 mm2. Half of the specimens were immediately tested, while the remaining specimens were tested after storage in 3 mMol/l sodium azide solution at 37°C for six months. The mode of fracture was examined. Bond strength values were analyzed with ANOVA and Student-Newman-Keuls tests. Results After 24 h of storage, mean bond strengths of 0.5% EGCG were significantly lower than those found for the other groups (p 0.05). Resin-dentin bond strengths after 6 months were not significantly different among the experimental groups (p > 0.05). Storage in water for 6 months resulted in a significant decrease in bond strength for the water control group only (p 0.05). Conclusion Pretreatment with EGCG preserved the bond of Adper Single Bond 2 to dentin after six months of storage equally well as pretreatment with chlorhexidine digluconate.

3D assessment of void and gap formation in flowable resin composites using optical coherence tomography.

Abstract: PURPOSE To investigate the effect of composite type and cavity size on gap and void formation using optical coherence tomography (OCT). MATERIALS AND METHODS Class I cavities of two depths (2 mm or 4 mm; 4 mm diameter) were prepared, treated with Tri-S Bond (Kuraray Medical), and bulk filled with either Surefil SDR Flow (SF; Dentsply) or Clearfil Majesty LV (MJ; Kuraray Medical) to form four groups. After 24 h, the specimens were 3D scanned using swept-source OCT (Santec) with 1310 nm laser at a 20 kHz sweep rate. In OCT tomograms, the bonding interface and the bulk of the restorations were evaluated. The percentage values of sealed interfaces (SP) and void volume (VP) for all groups were calculated and statistically analyzed using two- and one-way ANOVA and Tukey's post-hoc test. Selected specimens were cross sectioned and observed using a scanning electron microscope (SEM) and a confocal laser scanning microscope to confirm OCT findings. RESULTS The following values were obtained for SP and VP, respectively: SF-2mm: 92% and 0.08%; SF-4mm: 66% and 0.13%; MJ-2mm: 86% and 1.79%; MJ-4mm: 33% and 1.96%. Both composites showed a significant increase in gap formation at 4-mm cavity depth (p < 0.001). While SF showed a rather homogeneous bulk compared to MJ, cavity depth did not significantly affect the void volume fraction (p = 0.08). CONCLUSION The flowable composite with SDR (stress-decreasing resin) technology performed better than the conventional composite; however, bulk filling a 4-mm-deep cavity will compromise the sealing of the bonding interface regardless of the type of composite. OCT is a unique method of characterizing materials and their behaviors nondestructively and precisely.

Biomimetically- and hydrothermally-grown HAp nanoparticles as reinforcing fillers for dental adhesives.

Abstract: Purpose Differently prepared hydroxyapatite (HAp) nanoparticles were incorporated into the adhesive solution of a commercial adhesive system in order to evaluate the effect on microtensile bond strength to dentin. Materials and methods HAp nanoparticles (20 to 70 nm) were prepared by different processes (biomimetic and hydrothermal) and incorporated into the adhesive of the Adper Scotchbond Multi-Purpose (SBMP) system at various concentrations. Control (unfilled) and experimental groups (filled) were applied onto flat mid-coronal human dentin. Composite crowns were built up and cut into beams with a cross-sectional area of 0.65 ± 0.05 mm2. Specimens were fractured in tension and examined with a scanning electron microscope (SEM) for fractographic analysis. Microtensile bond strength (µTBS) data were analyzed using a two-way ANOVA and modified LSD test at a = 0.05. Analysis of the nanofiller distribution and ultramorphological characterization of the interface was performed by transmission electron microscopy (TEM). Results HAp nanoparticle incorporation into the adhesive of SBMP significantly influenced µTBS to dentin depending on the fillers and the concentration used. A significant increase of the mechanical strength was obtained for the adhesives containing 1% (wt/vol) biomimetic and 5% hydrothermal silanized HAp particles, while the other particle fractions did not influence µTBS significantly. 10% (wt/vol) HAp particles significantly lowered the µTBS irrespective of the particle type used. TEM micrographs revealed nanoparticle dispersion through the adhesive layer but no deposition on or penetration into the hybrid layer. Conclusions HAp nanoparticle incorporation into SBMP increased bond strength to dentin by cohesively reinforcing the interface adhesive layer. At a concentration of 10% (wt/vol), nanofiller incorporation had a negative effect on bond strength.

In vitro comparison of mechanical properties and degree of cure of a self-adhesive and four novel flowable composites

Abstract: Purpose To compare a self-adhesive with two low-shrinkage and two regular flowable resin-based composites (RBCs) in terms of degree of conversion (DC) as well as micromechanical (indentation modulus [E]; Vickers hardness [HV]) and macromechanical properties (flexural strength [σ], modulus of elasticity [Eflexural]) Materials and methods DC was investigated by an ATR-FTIR spectrometer at clinically relevant filling depths (01 mm, 2 mm, 4 mm, 6 mm bulk, 6 mm incremental) and irradiation times (10 s, 20 s, 40 s) Micro- and macromechanical properties were measured with an automatic microhardness indenter and a three-point bending test device after curing the specimens for 20 s and storing them in distilled water for 24 h at 37°C Fillers were visualized using a field emission scanning electron microscope (FE-SEM) Results were evaluated using one-way ANOVA, Tukey's HSD post-hoc test, Pearson's correlation and a multivariate analysis (α = 005) A Weibull analysis was used to assess σ Results N'Durance Dimer flow (6566%) reached the highest DC (at 2 mm depth, 20 s irradiation) In terms of macromechanical properties, EcuSphere-Flow (12982 MPa) for σ and Synergy D6 Flow (374 GPa) for Eflexural reached the highest values The highest micromechanical properties were measured for the self-adhesive RBC (Vertise Flow; E = 1081 GPa, HV = 6020 N/mm2) Reliability was highly influenced by filler weight (η2 = 077) and volume (η2 = 099) proportion Conclusion In the present study, the self-adhesive RBC showed the highest reliability, highest DC (together with one of the low-shrinkage RBCs), and highest micromechanical properties as well as good macromechanical properties Moreover, a curing time of 40 s and an incremental thickness not exceeding 2 mm appeared to be necessary for such results

Effect of chlorhexidine on the 18-month clinical performance of two adhesives.

Abstract: PURPOSE This study tested the hypothesis that 2% chlorhexidine (CHX) does not affect the 18-month clinical performance of two dentin adhesives, XP Bond (XPB) and XENO V (XEN). MATERIALS AND METHODS A total of 120 noncarious cervical lesions (NCCL) were selected and assigned to 4 groups: (1) XPB; (2) CHX prior to the application of XPB; (3) XEN; (4) CHX prior to the application of XEN. A hybrid composite resin, Esthet•X, was used for all restorations. Restorations were evaluated blindly at 6 and 18 months by two evaluators using the University of North Carolina (UNC)-modified USPHS criteria. Statistical analyses included the Mann Whitney and McNemar nonparametric tests (p < 0.05). RESULTS At 6 months, 91 (75.2%) restorations were evaluated, while 92 (76.7%) restorations were evaluated at 18 months. The 6-month/18-month overall retention rates (%) were 100/100 for XPB, 96.0/95.0 for CHX+XPB, 100/91.3 for XEN, and 100/95.8 for CHX+XEN with no statistical difference between any pair of groups at each recall. Sensitivity to air improved significantly for groups XPB, XEN, and CHX+XEN from pre-operative conditions to 1 week after insertion, to 6 and to 18 months after inserting. For group CHX+XPB, there was a statistically significant difference only between pre-operative conditions and 1 week after insertion. Marginal adaptation deteriorated for all groups, but no statistically significant differences were found. All other criteria remained statistically similar. CONCLUSION The application of CHX prior to the dentin adhesive did not influence the 6-month/18-month clinical performance of the two adhesives.

Dentin matrix component solubilization by solutions of pH relevant to self-etching dental adhesives.

Abstract: PURPOSE To evaluate the potential for phosphoric acid solutions - common constituents of dental adhesive systems - of varying pH to solubilize dentin matrix components (DMCs) from human dentin. MATERIALS AND METHODS Human dentin chips were ground under liquid nitrogen to a powder (ca 100 µm) and incubated at 4°C with agitation in phosphoric acid of pH 1, 2, 3, 4, 5, and 6 (1 g/4 ml; n = 4) for six days with solution changes each day. Estimates of daily protein release were made by UV spectrophotometry at 280 nm. Extract solutions were dialyzed for 7 days in reverse osmosis water, lyophilized, and weighed. Non-collagenous proteins (NCPs) and glycosaminoglycans (GAGs) were quantitated by dye-binding assays. 1D-PAGE for preliminary protein characterization and sandwich ELISA for presence of TGF-s1 were performed. The results were analyzed by ANOVA and regression (α <= 0.05). RESULTS Protein release was drastically reduced after the first few days, with the highest amounts obtained from pH 1. There was no significant difference in the quantity of DMCs solubilized by the different pH levels, but there was a significant logarithmic relation between release and pH, suggesting that greater DMC solubilization occurs with higher hydrogen ion concentrations. Dye binding assays confirmed the release of NCPs and GAGs at all pH levels. There were only subtle differences in protein bands observed between the different pH levels (1D-PAGE). Significant levels of TGF-s1 were identified from extraction at all pHs. CONCLUSION Acids at pH levels relevant to those used in commercial dentin adhesives are capable of solubilizing human DMCs, with release being related to hydrogen ion concentration.

Effect of resin cement type on the microtensile bond strength to lithium disilicate ceramic and dentin using different test assemblies

Abstract: PURPOSE: This study evaluated the microtensile bond strength (µTBS) of 3 different resin cements to lithium-disilicate ceramic using two assemblies: ceramic-cement-ceramic (CCC) and ceramic-cement-dentin (CCD). MATERIALS AND METHODS: The bonding surfaces of lithium disilicate ceramic blocks (5 × 5 × 4 mm) (Nblock = 90) were etched with 4% hydrofluoric acid for 20 s and silanized. Flat dentin surfaces of human third molars were conditioned according to the respective manufacturer's specifications for three types of resin cements (ML: Multilink, Ivoclar-Vivadent; PF: Panavia F, Kuraray; SB: Super Bond CB and aging condition (AC - thermocycling 12,000 times + water storage for 150 days). The µTBS bond strength test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using a scanning electron microscope to categorize the failure types. The data were statistically evaluated using 2-way ANOVA and Tukey's test (5%). RESULTS: While the mean µTBS of CCC assemblies were significantly influenced by the cement type (p 0.05). Without aging (DC), the mean µTBS (MPa) of SB (26.9) and PF (26.9) were significantly higher than ML (18.5) (p 0.05). In both CCC and CCD assemblies, pre-test failures were the least with SB cement. Regardless of the resin cement type employed and storage conditions, adhesive failures ranged between 35.3% and 88.9%, cohesive failures in cement between 2.3% and 35.3%, and cohesive failures in ceramic between 3.3% and 6.8%. CONCLUSION: SB resin cement demonstrated the highest bond strength to a lithium disilicate ceramic in both tests assemblies with and without aging conditions.

Effect of particle deposition parameters on silica coating of zirconia using a chairside air-abrasion device.

Abstract: Purpose: To evaluate the effect of nozzle distance, nozzle angle, and deposition duration on the silica content attained on zirconia by air abrasion. Materials and Methods: Disk-shaped zirconia (LAVA, 3M ESPE) (diameter: 10 mm, thickness: 2 mm) specimens (N = 54) were obtained. They were wet-ground finished using 600-, 800-, and 1200-grit silicone carbide abrasive papers in sequence and ultrasonically cleaned. The specimens were mounted in a specially designed apparatus that allowed the chairside air-abrasion device to be operated under standard conditions. Alumina-coated silica particles (CoJet Sand, 3M ESPE) were deposited on the zirconia disk surfaces varying the following parameters: a) nozzle distance (2, 5, 10 mm), and b) deposition duration (5, 13, 20 s) at two nozzle angles (45 and 90 degrees) under 2.5 bar pressure at three locations on each ceramic disk. The specimen surfaces were then gently air dried for 20 s. Silica content in weight percentage (wt%) was measured from 3 surfaces on each disk using Energy Dispersive X-ray Spectroscopy (EDS) (150X) in an area of 0.8 mm x 0.6 mm (n = 3 per group). Surface topographies were evaluated using SEM. Data were analyzed using ANOVA and Tukey's tests (alpha = 0.05). Results: Nozzle angle (p = 0.003) and deposition duration (p = 0.03) significantly affected the results, but nozzle distance (p = 0.569) did not. A significantly higher amount of silica (wt%) was achieved when the nozzle angle was 45 degrees to the surface in all distance-duration combinations (16.7 to 28.2 wt%) compared to the 90-degree nozzle angle (10.7 to 18.6 wt%) (p <0.001). The silica amount was significantly higher after 20-s deposition duration than after 13 s (p <0.05). EDS analysis demonstrated not only Si but also Al, Zr, and O traces on the substrate. SEM images indicated that deposition at a nozzle distance of 2 mm often created cavitations in zirconia. Conclusion: Effective silica deposition using a charside air-abrasion device can be achieved when the nozzle is held at 45 degrees to the surface with more than 2-mm nozzle distance for 20 s.

Effect of post-silanization heat treatments of silanized feldspathic ceramic on adhesion to resin cement.

Abstract: Sao Paulo State Univ UNESP, Dept Prosthodont & Dent Mat, Sao Jose Campos Dent Sch, Sao Jose Dos Campos, Brazil

Effect of polyacrylic acid on the interface and bond strength of self-adhesive resin cements to dentin.

Abstract: PURPOSE To examine the influence of 11.5% polyacrylic acid pretreatment on the interface and bond strength of self-adhesive resin cements (Maxcem Elite, RelyX Unicem, SeT) to dentin. MATERIALS AND METHODS Fifty-six third molars were randomly divided into seven groups: RelyX ARC as control (ARC), RelyX Unicem (RLXU), Maxcem Elite (MCE), SeT (ST), polyacrylic acid+RelyX Unicem (RLXU-P), polyacrylic acid+Maxcem Elite (MCE-P), and polyacrylic acid+SeT (ST-P). Resin composite blocks were luted to flat dentin. After storage in distilled water for 24 h, sticks with a cross-sectional area of ca 0.80 mm2 were obtained (n = 24 per group) and submitted to a microtensile bond strength (µTBS) test in a universal testing machine at a crosshead speed of 0.5 mm/min. Two sets from each group were sectioned mesiodistally in the center of the crown and observed with a scanning electron microscope at 4000X magnification. RESULTS The mean results of the µTBS test (MPa) followed by the same letter do not differ statistically significantly according to ANOVA and Tukey's post-hoc test (p < 0.05): ARC = 24.19 (± 6.90)a, RLXU-P = 23.12 (± 6.18)a, MCE-P = 13.09 (± 5.87)b, RLXU = 10.23 (± 2.88)b,c, and MCE = 8.14 (± 4.63)c. All SeT specimens failed during the cutting procedure. The hybrid layer was not observed for the self-adhesive resin cements, and resin tags were observed for RelyX Unicem and Maxem Elite when dentin was pretreated with polyacrylic acid. CONCLUSION Pretreatment with 11.5% polyacrylic acid was effective for bonding RelyX Unicem and Maxcem Elite to dentin.

A meta-analysis of the most indicated preparation design for porcelain laminate veneers.

Abstract: PURPOSE To evaluate the fracture strength of three different types of tooth preparation design for ceramic veneers and determine whether there is any correlation between the preparation performed and the type of failure observed, by means of a meta-analysis of published in vitro studies. MATERIALS AND METHODS Three databases were consulted to select the studies, considering previously established inclusion and exclusion criteria. The data extracted were submitted to statistical analysis by means of the software Review Manager 5.1, using the random effect statistical model with a confidence interval of 95%. RESULTS The results showed a decrease in mean dental fracture strength of 76.53 N in teeth with feathered incisal edge preparations, and 102.82 N for those with palatal chamfers when compared with nonprepared teeth, whereas the preparation with a butt joint showed no significant difference compared to nonprepared teeth (p = 0.37). Ceramic fractures occurred more frequently in the chamfer type than feathered incisal edge design. CONCLUSION The butt joint is the type of preparation that least affects the strength of the tooth and the chamfer preparation type is more susceptible to ceramic fractures.

Experimental and clinical evaluation of a self-etching and an etch-and-rinse adhesive system.

Abstract: Purpose To assess the one-step self-etching adhesive iBond Gluma inside (1-SE) and the two-step etch-and rinse adhesive Gluma Comfort Bond (2-ER), both used in combination with the fine particle hybrid composite Venus, in a laboratory and in a prospective clinical study. Materials and methods In the in vitro study, tooth-composite interaction, microleakage, and adhesive failure of 8 Class V restorations per system were evaluated by light and scanning electron microscopy. In the in vivo study, 90 paired Class III/IV restorations were scored over 48 months (modified USPHS criteria). Cumulative failure rates (CFR) were calculated. Results In vitro, microleakage and adhesive failure at enamel margins were significantly increased with 1-SE in comparison with 2-ER. With 1-SE, micromechanical interlocking at enamel was reduced and pores within the adhesive layer arose. In vivo, after 48 months with 1-SE, decreased marginal integrity and an increased number of dark marginal color lines were observed. Conclusion Because the results of the 4-year clinical study showed lower esthetics and marginal integrity for the 1-SE adhesive, its use should be viewed critically, which is in line with the reduced enamel-adhesive-composite interaction found in vitro.

Effect of hydrophilicity on the compatibility between a dual-curing resin cement and one-bottle simplified adhesives.

Abstract: PURPOSE To evaluate the effect of the hydrophilicity of adhesives on the compatibility between one-bottle simplified adhesives and a dual-curing resin cement. MATERIALS AND METHODS Three experimental and two commercial adhesives (All-Bond Universal, OptiBond Allin- One) with the same or similar pH and various degrees of hydrophilicity were tested in this study. Extracted human dentin was treated with each adhesive and bonded with a dual-curing resin cement (Duolink), which was either light cured or chemically (self) cured (n = 10). Shear bond strength was tested using the Ultradent jig method, and failure modes were determined using a stereomicroscope. Water contact angle (as a measure of hydrophilicity/-phobicity) was measured on a fully cured adhesive (n = 10). The data were analyzed statistically by ANOVA and Tukey's test. The quantitative relationship between the hydrophilicity and bond strength differences was analyzed (confidence level 95%). RESULTS Among the experimental adhesives, differences in bond strengths between light-curing and self-curing modes were larger for the more hydrophilic adhesives. For the commercial adhesives, Optibond All-in-One had a lower contact angle than All-bond Universal (p < 0.05). Bond strength (MPa) values for Optibond All-in-One and All-bond Universal were 29.6 and 31.5, respectively (light cured), and 1.9 and 30.0, respectively (self-cured). Adhesive failure was a predominant mode for all adhesives except for All-Bond Universal. Regression analysis indicated a linear correlation between adhesives' hydrophilicity and bond strength differences (p < 0.05). CONCLUSION The more hydrophilic adhesives were less compatible (larger bond strength differences between different curing modes) with this dual-curing resin cement. All-bond Universal is more hydrophobic than Optibond All-in-One and it is compatible with this self-/dual-curing resin cement.

Repair Bond Strength in Aged Methacrylate- and Silorane-based Composites

Abstract: PURPOSE To evaluate the tensile bond strength at repaired interfaces of aged dental composites, either dimethacrylate- or silorane-based, when subjected to different surface treatments. MATERIALS AND METHODS The composites used were Filtek P60 (methacrylate-based, 3M ESPE) and Filtek P90 (silorane-based, 3M ESPE), of which 50 slabs were stored for 6 months at 37°C. The surface of adhesion was abraded with a 600-grit silicone paper and the slabs repaired with the respective composite, according to the following surface treatment protocols: G1: no treatment; G2: adhesive application; G3: silane + adhesive; G4: sandblasting (Al2O3) + adhesive; G5: sandblasting (Al2O3) + silane + adhesive. After 24-h storage in distilled water at 37°C, tensile bond strength (TBS) was determined in a universal testing machine (Instron 4411) at a crosshead speed of 0.5 mm/min. The original data were submitted to two-way ANOVA and Tukey's test (α = 5%). RESULTS The methacrylate-based composite presented a statistically significantly higher repair potential than did the silorane-based resin (p = 0.0002). Of the surface treatments for the silorane-based composite, aluminum-oxide air abrasion and adhesive (18.5 ± 3.3MPa) provided higher bond strength than only adhesive application or the control group without surface treatment. For Filtek P60, the control without treatment presented lower repair strength than all other groups with surface treatments, which were statistically similar to each other. The interaction between the factors resin composite and surface treatment was significant (p = 0.002). CONCLUSION For aged silorane-based materials, repairs were considered successful after sandblasting (Al2O3) and adhesive application. For methacrylate resin, repair was successful with all surface treatments tested.

Effect of water storage on bond strength of self-adhesive resin cements to zirconium oxide ceramic.

Abstract: Purpose To evaluate the microshear bond strength of resin cements to yttrium-stabilized tetragonal zirconium oxide surfaces after water storage for 24 h or 1 year Materials and methods Four self-adhesive (BisCem, G-Cem, RelyX Unicem, SeT) and one conventional resin cement (RelyX ARC) were tested The materials were mixed and inserted in tubes (075 mm diameter × 1 mm height) that were placed over the zirconium oxide surface Specimens were tested after 24-h or 1-year water storage Microshear testing was performed using a universal testing machine Shear bond strength results were analyzed using two-way ANOVA and Tukey's test (5%) Results After 24-h water storage, no difference was found between G-Cem and RelyX Unicem resin cements; however, their bond strength means to zirconium oxide were statistically higher than RelyX ARC The bond strength values of all resin cements dropped significantly after 1 year of water storage G-Cem presented the highest values among cements after long-term water exposure Conclusions One-year water storage decreased the microshear bond strengths to zirconium oxide for all resin cements tested

Effects of silane application on luting fiber posts using self-adhesive resin cement.

Abstract: Purpose To evaluate the effects of different glass-fiber post surface treatments on the bond strength to root dentin. Materials and methods Fifty bovine incisors were used in this study. After removing the crowns, the teeth were endodontically treated. The roots were randomly divided into five groups according to post surface treatment. The groups were as follows: CO (Control) - no treatment; G1 - RelyX Ceramic Primer (silane) only; G2 - silane and Solobond M; G3 - silane and Scotchbond Adhesive; G4 - silane and Excite. For post cementation, RelyX Unicem was used according to the manufacturer's recommendation and the roots were stored in a light-proof container with 100% relative humidity for 24 h. The specimens were transversally sectioned. Subsequently, the cervical, middle, and apical regions of the root were positioned in a push-out device and tested at 0.5 mm/min using a universal testing machine (Instron). The data were statistically analyzed with two-way ANOVA and Tukey's post-hoc test. The fractured specimens were then observed under a stereoscopic loupe at 60X magnification. Results No significant difference in bond strength was found among the groups that received a silane or silane plus an adhesive system (p > 0.05). However, the CO (no silane) showed the lowest bond strength. Regarding G1, G2, G3, and G4, the cervical region of the root canal attained better bond strengths than did the middle or apical regions. The most frequent failure mode occurred at the cement/dentin interface. Conclusion Silane application may be necessary to improve the adhesion of fiber posts luted with the self-adhesive resin cement evaluated here. The application of an adhesive layer between the fiber post and resin cement did not have any influence on the bond strength when the silane coupling was previously used.

Influence of MDPB-containing Primer on Streptococcus Mutans Biofilm Formation in Simulated Class I Restorations.

Abstract: PURPOSE To evaluate the activity of a methacryloyloxydodecylpyridinium bromide (MDPB)-containing self-etching primer (Clearfil Protect Bond) against Streptococcus mutans and its ability to reduce biofilm formation on standardized experimental Class I restorations in vitro. MATERIALS AND METHODS Forty experimental Class I round restorations were prepared on enamel-dentin slabs using different adhesive strategies: group 1 = MDPB-containing adhesive system (Clearfil Protect Bond); group 2 = MDPB-free self-etching adhesive system (Clearfil SE Bond); group 3: MDPB-containing self-etching primer in combination with a fluoride-free bonding agent; group 4: MDPB-free self-etching primer in combination with a fluoride-containing bonding agent; group 5: a three-step etch-and-rinse adhesive system (Adper Scotchbond Multi Purpose). A Streptococcus mutans biofilm was grown for 48 h on the restoration surfaces and subsequently evaluated using scanning electron microscopy on three different areas: enamel, composite, and interface surfaces. Statistical analysis was performed by multiple ANOVA after data transformation. RESULTS Specimens in groups 2, 4 and 5 showed greater biofilm formation than those in groups 1 and 3 (p < 0.001) on all investigated substrates (enamel, composite, and interface areas). CONCLUSIONS Specimens prepared with an MDPB-containing primer exhibited significant decreases in biofilm formation on Class I restorations in vitro. Further in vitro and in vivo studies are required to clarify the role of quaternary ammonium compounds in reducing bacterial biofilm formation on restoration surfaces.

Starch tubing: an alternative method to build up microshear bond test specimens.

Abstract: PURPOSE To evaluate an alternative device using starch tubes to build up resin composite specimens for microshear bond tests. MATERIALS AND METHODS Twenty human molars were selected and sectioned mesiodistally to obtain two sections. The teeth were randomly divided into 4 groups (n = 10) according to the adhesive system - a two-step etch-and-rinse adhesive (Adper Single Bond) and a two-step self-etching adhesive (Clearfil SE Bond) - and the type of tube, starch or polyethylene. The tubes were evaluated under a stereomicroscope at 25X magnification to observe the variation in internal diameter. The resin composite was bonded to flat enamel surfaces using one of the adhesive systems and tube types. After 24 h storage in distilled water, the microshear bond strength (µSBS) was determined and the fracture pattern was analyzed under a stereomicroscope (400X magnification). The microshear bond strength values were subjected to two-way ANOVA. The chi-square test was used to compare pre-test failures and fracture patterns between the groups (p < 0.05). RESULTS The type of tube, the adhesive system, and their interaction did not influence the bond strength values (p = 0.062, p = 0.122, and p = 0.301, respectively). No significant differences were observed for pre-test failures or fracture patterns (p = 0.320 and p = 0.561, respectively). CONCLUSION Using starch tubes is an alternative to build up composite resin specimens for microshear bond strength testing with the two tested adhesive systems.

Efficacy of surface treatments on the bond strength of resin cements to two brands of zirconia ceramic.

Abstract: Univ Bologna, Sch Dent, Dept Prosthodont, Dent Mat Sect,Alma Mater Studiorum, I-40125 Bologna, Italy

Does Operatory Field Isolation Influence the Performance of Direct Adhesive Restorations

Abstract: PURPOSE To evaluate the influence of different adhesive strategies (etch-and-rinse and self-etching adhesives) and type of field isolation (absolute or relative) on the clinical performance of restorations of noncervical carious lesions (NCCLs). MATERIALS AND METHODS One hundred forty NCCLs were selected from 38 patients, according to previously established inclusion/exclusion criteria, and assigned to one of four groups (n = 35): etch-and-rinse/rubber-dam (ERR), etch-and-rinse/cotton roll (ERC), self-etching/rubber-dam (SER) and self-etching/cotton roll (SEC). The adhesive systems used were: Adper Single Bond 2 (3M ESPE) and Adper SE Plus (3M ESPE), with restorations made using a composite resin (Z350, 3M ESPE). Using the USPHS modified criteria, 140 restorations were evaluated by two calibrated examiners at 5 different times: immediately after placement, at 7 days, and 2, 6, and 12 months. In order to evaluate the presence of gingival recession after the use of the #212 rubber-dam clamp, the clinical crowns of the teeth from groups ERR and SER were measured at six different periods (baseline, immediately, and at 7 days, 2, 6, and 12 months). Data were subjected to McNemar's, chi-square, and Student's t-tests. RESULTS Both adhesive strategies reduced tooth sensitivity beyond the second period of evaluation (7 days); tooth sensitivity disappeared after the third period of evaluation (2 months). There were no statistically significant differences between the adhesive techniques or isolation techniques, except for a Bravo score for marginal discoloration in group SEC at 6 months, which was significantly different from the other groups. The rubber-dam isolation technique was more uncomfortable for the patient and resulted in short-term gingival recession. CONCLUSION No significant differences were found between the types of isolation or adhesive strategy in this clinical evaluation, with the exception of 2 restorations in group SEC that showed marginal discoloration, possibly due to inadequate enamel etching by the self-etching adhesive. Class V restorations perform equally well placed with or without rubber-dam.

Effect of different surface treatments on adhesion of In-Ceram Zirconia to enamel and dentin substrates.

Abstract: PURPOSE: Resin bonding of In-Ceram Zirconia (ICZ) ceramics is still a challenge, especially for minimally invasive applications. This study evaluated the adhesion of ICZ to enamel and dentin after different surface treatments of the ceramic. MATERIALS AND METHODS: ICZ ceramic specimens (diameter: 6 mm; thickness: 2 mm) (N = 100) were fabricated following the manufacturer's instructions and randomly assigned to 5 groups (n = 20), according to the surface treatment methods applied. The groups were as follows: group C: no treatment; group SB: sandblasting; group SCS-S: CoJet+silane; group SCS-P: CoJet+Alloy Primer; group GE-S: glaze+ hydrofluoric acid etching (9.6%) for 60 s+silane. Each group was randomly divided into two subgroups to be bonded to either enamel or dentin (n = 10 per group) using MDP-based resin cement (Panavia F2.0). All the specimens were subjected to thermocycling (5000x, 5°C-55°C). The specimens were mounted in a universal testing machine and tensile force was applied to the ceramic/cement interface until failure occurred (1 mm/min). After evaluating all the debonded specimens under SEM, the failure types were defined as either "adhesive" with no cement left on the ceramic surface (score 0) or "mixed" with less than 1/2 of the cement left adhered to the surface with no cohesive failure of the substrate (score 1). The data were statistically evaluated using 2-way ANOVA and Tukey's tests (α = 0.05). RESULTS: The highest tensile bond strength for the enamel surfaces was obtained in group GE-S (18.1 ± 2 MPa) and the lowest in group SB (7.1 ± 1.4 MPa). Regarding dentin, group CSC-P showed the highest (12 ± 1.3 MPa) and SB the lowest tensile bond strength (5.7 ± 0.4 MPa). Groups SB, CSC-S, CSC-P, and GE-S did not show significant differences between the different surface treatments on either enamel or dentin surfaces (p < 0.05, p < 0.001, respectively). Groups CSC-P and GE-S presented similar bond strength for both the enamel and dentin substrates (p < 0.8 and p < 0.9), respectively. While on enamel substrates, exclusively adhesive failures from ICZ (score 0) were found, on dentin exclusively mixed failures were observed (score 1). CONCLUSION: Adhesion of ICZ to both enamel and dentin can be improved when ceramics are glazed, etched, and silanized, or sandblasted, primed, and cemented with an MDP-based cement.

Effect of surface conditioning modalities on the repair bond strength of resin composite to the zirconia core / veneering ceramic complex.

Abstract: Univ Zurich, Dent Mat Unit, Ctr Dent & Oral Med, Clin Fixed & Removable Prosthodont & Dent Mat Sci, CH-8032 Zurich, Switzerland

Effects of warm air drying on water sorption, solubility, and adhesive strength of simplified etch-and-rinse adhesives.

Abstract: PURPOSE To evaluate the effects of the temperature of air used for solvent evaporation on water sorption, solubility, and ultimate tensile strength (UTS) of simplified etch-and-rinse adhesives. MATERIALS AND METHODS Four commercial simplified etch-and-rinse adhesives (Adper Single Bond 2 [SB]; Te Econom [TE]; XP Bond [XP] and Ambar [AM]) were selected. Disk-shaped specimens were prepared by dispensing the uncured resin into a mold (5.8 mm x 0.8 mm). Solvent evaporation was performed using a warm (60°C) or cold (20°C) air stream for 40 s. After desiccation, the cured specimens were weighed and then stored in distilled water for evaluation of the water diffusion kinetics over a 28-day period. For the UTS measurement, hourglass-shaped specimens of adhesives were prepared and tested in tension. The data from each test were evaluated with two-way ANOVA and Tukey's test at a confidence level of 95%. RESULTS Water sorption and solubility varied significantly between materials, but no significant difference was observed between warm and cold conditions (p > 0.05). TE and AM showed the lowest water sorption and solubility (p < 0.05). For SB, TE, and XP, the use of a warm air stream resulted in higher ultimate tensile strength (p < 0.05) in both experimental conditions. CONCLUSIONS The water sorption and solubility of the materials seem to be more influenced by their composition than by the temperature used for solvent evaporation. For some adhesives, the use of a warm air stream can yield higher ultimate tensile strength.

Long-term bond of glass ceramic and resin cement: evaluation of titanium tetrafluoride as an alternative etching agent for lithium disilicate ceramics.

Abstract: Purpose To evaluate in vitro the effect of using titanium tetrafluoride as an alternative etchant prior to the silanization of the bonding surface on the long-term resin bond strength to lithium disilicate ceramic. Materials and methods Disk-shaped specimens made of lithium disilicate ceramic were ground with abrasive paper, then etched with aqueous solutions (2.5% and 5%) of titanium tetrafluoride for 60 s, 120 s and 240 s. Positive control specimens were etched with 5% hydrofluoric acid for 20 s and negative control specimens were not etched. Afterwards, bonding surfaces of all specimens were silanized. Plexiglas tubes filled with a composite resin were bonded to the specimens using an alignment apparatus and a composite luting resin. After storage in 37°C tap water for three days (n = 8) and after storage in 37°C tap water for 150 days interrupted by 5 x 7500 thermal cycles (n = 8), tensile bond strength (TBS) was measured in a universal testing machine at a crosshead speed of 2 mm/min. Results After artificial aging, all specimens etched with titanium tetrafluoride debonded spontaneously resulting in a TBS of 0 MPa. Therefore, statistical analysis revealed a highly significant difference between the positive control and the test groups after 150 days storage. Conclusion Etching the bonding surface of lithium disilicate ceramic restorations with hydrofluoric acid is still a "gold standard" and cannot be replaced by titanium tetrafluoride.

Shrinkage kinetics of a methacrylate- and a silorane-based resin composite: effect on marginal integrity.

Abstract: Purpose: To evaluate the relation between the linear displacement (LD), shrinkage force (SF) and marginal adaptation of a methacrylate- and a silorane-based composite. Materials and Methods: The LD and SF of 8 samples made of Filtek Supreme XT (methacrylate-based composite) and Filtek Silorane (silorane-based composite) were measured for 180 s from the start of polymerization. Large bulk-filled Class I cavities were restored with both resin composites, and two C-factors were simulated by applying the same adhesive system in different ways: the Silorane System Adhesive (SSA) was applied on enamel and dentin (C-factor 3.5) or only on enamel margins (C-factor of 0.4). Percentages of continuous margins (%CM) were quantitatively assessed with SEM before and after simultaneously loading with 1.2 million mechanical occlusal cycles (49 N; 1.7 Hz) and 3000 thermal cycles (5°C to 50°C) under dentinal fluid simulation. Results: Significantly lower scores of LD and SF were observed for Filtek Silorane (LD: 12.0 µm ± 1.3, SF: 13.7 N ± 1.0) than for Filtek Supreme XT (LD: 25.0 µm ± 0.6, SF: 36.3 N ± 2.9). Both variables, ie, composite type and C-factor, had a significant effect on marginal adaptation (p < 0.05). In the groups with high C-factor (SSA was applied on the entire cavity surface) percent of continuous margin (%CM) (mean ± SD) before and after loading, respectively, was 24.4 ± 16.6 and 2.1 ± 2.4 for Filtek Supreme XT, and 58.8 ± 9.9 and 35.4 ± 4.1 for Filtek Silorane. When adhesion was confined to enamel margins (lower C-factor), %CM before and after loading, respectively, increased to 76.1 ± 9.6 and 64.2 ± 11.5 for Filtek Supreme XT, and 96.6 ± 1.7 and 94.2 ± 2.1 for Filtek Silorane. Conclusions: The silorane-based composite exhibited significantly lower shrinkage forces and better marginal adaptation than did the methacrylate-based composite.

Silica-based Nano-coating on Zirconia Surfaces Using Reactive Magnetron Sputtering: Effect on Chemical Adhesion of Resin Cements

Abstract: Results: Resin cement type (p < 0.05), surface conditioning method (p < 0.05), and aging condition (p < 0.05) had a significant effect on the bond strength results. Interactions were also significant (p < 0.05). In the nonaged condition, while control groups presented the lowest results with all cements (0 to 5.2 MPa), the airabraded group in combination with RelyX U100 resulted in the highest SBS (21.8 ± 6.7 MPa). After aging, the SBS results decreased in the air-abraded groups for all cements (4.54 to 9.44 MPa) and showed no statistical significance compared to the Si-based nanocoated groups (4.24 to 6.44 MPa). After air-abrasion and primer application, only Panavia F and RelyX U100 cements showed exclusively mixed failures, but after nanofilm coating and silanization, all cements showed exclusively mixed failures with and without aging. Conclusion: Chemical adhesion of the resin cements tested to zirconia was similar after silica-based nanofilm deposition and air abrasion followed by primer application.