Effect of Extra Hydrophobic Resin Layer on Bonding of Universal Adhesive Systems to Enamel.

OBJECTIVE: The objective of this study was to compare the effect of solvent in universal adhesives (UA) and the application of an extra layer of hydrophobic bonding resin on enamel shear bond strengths (SBS). METHODS AND MATERIALS: Crowns of 224 bovine mandibular incisors were embedded in acrylic resin, wet-polished up to 600-grit silicon carbide paper and assigned to 3 UAs with different solvents (n=32): ethanol-based UA (ADU, AdheSE Universal, Ivoclar Vivadent); isopropanol-based UA (PBU, Prime&Bond Universal, Dentsply Sirona); and acetone-based UA (OPT, OptiBond Universal, Kerr Co). The same UAs were also applied with an extra layer of a hydrophobic bonding resin (HLB, Heliobond, Ivoclar Vivadent): ADU + HLB; PBU + HLB; and OPT + HLB. HLB alone was used as control. Enamel was etched with 37.5% H3PO4 (Kerr Gel Etchant, Kerr Co) for 15 seconds, rinsed with water, and air dried. UAs were applied according to the respective manufacturer's instructions. After adhesive application, composite cylinders (Filtek Z250, 3M Oral Care) were built up and light-cured (40 seconds/increment, 40 J/cm2) keeping the light tip in contact with the mold. Specimens were stored in water for 24 hours (24H) or for 6 months (6M). A knife-edged metallic rod (Ø=2.8-mm semicircular notch) loaded the composite cylinders until fracture. Mode of failure was analyzed with optical microscopy (40×). Statistics included twoway analysis of variance (ANOVA; adhesive strategy and water storage) and Tukey honestly significant difference (HSD) post hoc test (α=95%). RESULTS: Mean enamel SBS ranged from 3.6 (±2.2) MPa (HLB/6M) to 24.7 (±7.1) MPa (ADU + HLB/6M). ANOVA revealed significant differences for adhesive strategy (p≤0.001) but no significant differences for water storage (p>0.05). All UAs resulted in similar mean enamel SBS with or without an extra layer of HLB at 24H. After 6M, only ADU resulted in higher enamel SBS when an extra layer of HLB was applied. All UAs resulted in higher mean enamel SBS than HLB (control). Most failures were adhesive exception for PBU/HLB/6M, which had mostly mixed failures. CONCLUSIONS: UAs resulted in statistically higher enamel SBS than the nonsolvated hydrophobic bonding resin (control), regardless of the solvent in their composition. Application of an extra layer of hydrophobic bonding resin over UAs did not improve mean enamel SBS for isopropanol- and acetone-based UAs but did improve mean enamel SBS for the ethanol-based UA after 6M. Resin composite bonding to enamel using a hydrophobic bonding resin alone is not recommended.

In Vitro Performance of Different Universal Adhesive Systems on Several CAD/CAM Restorative Materials After Thermal Aging.

OBJECTIVE: To evaluate the microshear bond strength (mSBS) of 10 universal adhesive systems applied on five different CAD/CAM restorative materials, immediately and after thermal aging. METHODS AND MATERIALS: Five CAD/CAM materials were selected: 1) feldspathic glass ceramic (FeCe); 2) pre-polymerized reinforced resin composite (ReRC); 3) leucite-reinforced glass ceramic (LeGC); 4) lithium disilicate (LiDi); and 5) yttrium-stabilized zirconium dioxide (ZiDi). For each material, 15 blocks were cut into four rectangular sections (6 × 6 × 6 mm; n=60 per group) and processed as recommended by the respective manufacturer. For each indirect material, the following adhesive systems were applied according to the respective manufacturer's instructions: 1) AdheSE Universal [ADU]; 2) All-Bond Universal [ABU]; 3) Ambar Universal [AMB]; 4) Clearfil Universal Bond [CFU]; 5) Futurabond U [FBU]; 6) One Coat 7 Universal [OCU]; 7) Peak Universal Bond [PUB]; 8) Prime&Bond Elect [PBE]; 9) Scotchbond Universal Adhesive [SBU]; 10) Xeno Select [XEN, negative control]. After the application of the adhesive system, cylinder-shaped transparent matrices were filled with a dual-curing resin cement (NX3) and light cured. Specimens were tested in shear mode at 1.0 mm/min (mSBS), after 24 hours and 10,000 thermal cycles (TC). All data were submitted to statistical analysis (α=0.05). RESULTS: For FeCe, there was no significant decrease in mean mSBS for AMB, FBU, and SBU after TC when compared at 24 hours. For ReRC, AMB and SBU showed higher mean mSBS when compared to CFU and XEN, after 24 hours and TC. For LiDi, FBU and OCU showed higher mean mSBS when compared to CFU and XEN, after 24 hours and TC. For LeGC, AMB and PUB showed higher mean mSBS when compared to XEN, after 24 hours and TC. For ZiDi, OCU and SBU showed higher mean mSBS when compared to XEN, after 24 hours and TC. In addition, PBE and XEN showed the lowest mean mSBS after TC with higher percentage of bond strength reduction. CONCLUSIONS: The mean mSBS among the different universal adhesives varied widely for each CAD/CAM material used. In addition, most universal adhesives underwent a statistically significant bond strength reduction after TC.

Effect of Methacryloyloxydecyl Dihydrogen Phosphate-Containing Silane and Adhesive Used Alone or in Combination on the Bond Strength and Chemical Interaction With Zirconia Ceramics Under Thermal Aging.

CLINICAL RELEVANCE: Achieving durable bonding to zirconia is fundamental for the application of a methacryloyloxydecyl dihydrogen phosphate (MDP)-containing silane solution or an MDP-containing silane solution associated with an MDP-containing universal adhesive. SUMMARY: Objectives: To evaluate the effect of a methacryloyloxydecyl dihydrogen phosphate (MDP)-containing silane coupling agent and universal adhesive, used alone or in combination, on the microshear bond strength (µSBS) to zirconia after 24 hours of water storage (24h) and after 10,000 thermocycles (TC), complemented with chemical analysis of the surface to establish the presence of MDP on the surface of the zirconia after bonding procedures.Methods and Materials: Thirty computer-aided design/computed-aided manufacturing blocks of zirconia were cut into four sections (6×6×6 mm) and sintered. Zirconia sections (n=96) were assigned to 24 groups according to three factors: 1) silane (no silane, Monobond S [MBS], Monobond P [MB+]), 2) adhesive + resin cement (no adhesive + Enforce [ENF], no adhesive + RelyX Ultimate [REX], Prime&Bond Elect + Enforce [PBE/ENF], Scotchbond Universal + RelyX Ultimate [SBU/REX]), and 3) thermocycling (no thermocycling [24h], 10,000 thermocycles [TC]). Upon silane/adhesive application, cylinder-shaped matrices were filled with resin cement and light cured. Specimens were tested in µSBS (1.0 mm/min) after 24h or TC. The µSBS data were analyzed using twoway ANOVA and Tukey's post hoc test (α=0.05). In addition, micro-Raman spectroscopy was used to analyze the zirconia surface for immediate chemical interaction analysis (n=24).Results: For the 24h condition, PBE/ENF resulted in lower mean µSBS than both groups with silane without PBE (MBS and MB+ groups; p<0.001). SBU alone or MB+ alone and MB+ associated with SBU showed the highest mean µSBS (p<0.001). For the TC condition, all groups showed a significant decrease in mean µSBS compared with those of 24h (p<0.001), with the exception of MB+ associated to SBU (p>0.05). However, the application of MB+ alone or MB+ associated to SBU resulted in higher mean µSBS (p<0.001) after TC than the remaining TC groups. In terms of chemical interaction, only the SBU groups, alone or combined with both of the silane agents, were associated with the methacrylate groups after rinsing.Conclusions: The results of the current study support the use of an MDP-containing silane solution or an MDP-containing silane solution associated with an MDP-containing universal adhesive for bonding to air-abraded zirconia, as a more stable bonding after thermocycling.

Does a Self-etching Ceramic Primer Improve Bonding to Lithium Disilicate Ceramics? Bond Strengths and FESEM Analyses.

OBJECTIVE:: To compare the effect of hydrofluoric acid (HF) vs self-etching ceramic primer on resin cement microshear bond strength (µSBS) and ultramorphology of lithium disilicate (LD) ceramic. METHODS AND MATERIALS:: LD (IPS e.max CAD, Ivoclar Vivadent) blocks (14×4×2 mm3) were polished to 1200 grit and assigned to nine groups (n=5): CON: control, no LD surface treatment; IVO: 5.0% HF (IPS Ceramic Etching Gel, Ivoclar Vivadent); VIT: 5.0% HF (Vita Ceramics Etch, VITA Zahnfabrik); FGM: 5.0% HF (Condac Porcelana, FGM); ULT: 9.0% HF (Porcelain Etch, Ultradent); PRM: 9.6% HF (Premier Porcelain Etch Gel, Premier); BIS: 9.5% HF (Porcelain Etchant, Bisco Inc); DEN: 10.0% HF (Condicionador de Porcelanas, Dentsply Brazil); and MEP: self-etching ceramic primer (Monobond Etch & Prime, Ivoclar Vivadent). For all HF groups and control, an MDP-containing silane solution (MB+, Monobond Plus, Ivoclar Vivadent) was applied on rinsing the HF gel and air drying. Three transparent matrices for each specimen were filled with light-cured resin cement (Variolink Veneer, Ivoclar Vivadent). After storage in water for 48 hours at 37°C, specimens were tested in shear mode to measure µSBS. Mode of failure was analyzed at 50×. Statistical analysis included one-way analysis of variance and the Duncan post hoc test (α=0.05). Thirty-six additional LD specimens were assigned to the same experimental groups (n=4) and observed under a field-emission scanning electron microscope (FESEM) at magnifications ranging from 10,000× to 100,000×. RESULTS:: IVO resulted in statistically higher mean µSBS than all the other groups. MEP resulted in statistically lower µSBS than all HF groups. The failure mode for MEP was predominantly adhesive. The most frequent failure mode for the HF groups was mixed. CON resulted in 100% pretesting failures. For FESEM, no retentive pattern was observed for CON specimens. MEP resulted in the least pronounced etching pattern, few areas around crystals exhibited a slight increase in retention pattern compared to the control group. All HF gels created microporosities on the LD surface with distinct etching patterns. VIT and DEN resulted in an LD ultramorphology that suggested overetching. CONCLUSIONS:: HF etching followed by a silane solution resulted in higher bond strengths than a self-etching ceramic primer. Some HF gels may cause overetching of the LD intaglio surface.

Masking of Enamel Fluorosis Discolorations and Tooth Misalignment With a Combination of At-Home Whitening, Resin Infiltration, and Direct Composite Restorations.

This clinical report illustrates a conservative technique to mask enamel discolorations in maxillary anterior teeth caused by hypomineralization associated with enamel fluorosis and subsequent direct resin composite to improve the anterior esthetics. The treatment consisted of at-home whitening with 10% carbamide peroxide gel with potassium nitrate and sodium fluoride in a custom-fitted tray to mask the brown-stained areas, followed by resin infiltration to mask the white spot areas. An existing resin composite restoration in the maxillary right central incisor was subsequently replaced after completion of the whitening and resin infiltration procedures, whereas the two misaligned and rotated maxillary lateral incisors were built up with direct resin composite restorations to provide the illusion of adequate arch alignment, as the patient was unable to use orthodontic therapy.

Microshear Bond Strength of Resin Cements to Lithium Disilicate Substrates as a Function of Surface Preparation.

OBJECTIVES: To investigate the effect of hydrofluoric acid (HF) etching, silane solution, and adhesive system application on the microshear bond strength (µSBS) of lithium disilicate glass-ceramic (LD) to three resin cements. MATERIALS AND METHODS: Circular bonding areas were delimited on the lithium disilicate surfaces using a perforated adhesive tape. Specimens were assigned to 18 subgroups (n=12) according to surface treatment: NT = no treatment; HF = 4.8% HF for 20 seconds; silane solution: (1) no silane; (2) Monobond Plus, a silane/10-methacryloyloxydecyl dihydrogen phosphate solution for 60 seconds; (3) Monobond Plus+ExciTE F DSC, a dual-cure adhesive; and resin cement: (1) Variolink II, a bisphenol A diglycidyl ether dimethacrylate (bis-GMA)-based, hand-mixed, dual-cure resin cement; (2) Multilink Automix, a bis-GMA-based, auto-mixed, dual-cure resin cement; (3) RelyX Unicem 2, a self-adhesive, auto-mixed, dual-cure resin cement. Tygon tubes (Ø=0.8 mm) were used as cylinder matrices for resin cement application. After 24 hours of water storage, the specimens were submitted to the µSBS test. Mode of failure was evaluated under an optical microscope and classified as adhesive, mixed, cohesive in resin cement, or cohesive in ceramic. Data were statistically analyzed with three-way analysis of variance and Dunnett test (p<0.05). RESULTS: When means were pooled for the factor surface treatment, HF resulted in a significantly higher µSBS than did NT (p<0.0001). Regarding the use of a silane solution, the mean µSBS values obtained with Monobond Plus and Monobond Plus+ExciTE F DSC were not significantly different but were higher than those obtained with no silane (p<0.001). Considering the factor resin cement, Variolink II resulted in a significantly higher mean µSBS than did RelyX Unicem 2 (p<0.03). The mean µSBS for Multilink Automix was not significantly different from those of Variolink II and RelyX Unicem 2. According to Dunnett post hoc test (p<0.05), there was no significant difference in µSBS between the different resin cements for HF-etched and silanized (with or without adhesive application) LD surfaces. CONCLUSION: LD may benefit from pretreatment of the inner surface with HF and silanization, regardless of the resin cement used.

GidB mutation as a phylogenetic marker for Q1 cluster Mycobacterium tuberculosis isolates and intermediate-level streptomycin resistance determinant in Lisbon, Portugal.

Development of streptomycin resistance in Mycobacterium tuberculosis is usually associated with mutations in rpsL and rrs genes, although up to 50% of clinical streptomycin-resistant isolates may present no mutation in either of these genes. In the present report we investigate the role of gidB gene mutations in streptomycin resistance. We have analyzed 52 streptomycin-resistant and 30 streptomycin-susceptible Mycobacterium tuberculosis clinical isolates by sequencing and endonuclease analysis of the gidB and rpsL genes. All clinical isolates were genotyped by 12-loci MIRU-VNTR. The gidB gene of 18 streptomycin-resistant isolates was sequenced and four missense mutations were found: F12L (1/18), L16R (18/18), A80P (4/18) and S100F (18/18). The remaining isolates were screened by endonuclease analysis for mutations A80P in the gidB gene and K43R in the rpsL gene. Overall, mutation A80P in the gidB gene was found in eight streptomycin-resistant isolates and 11 streptomycin-susceptible multidrug-resistant isolates. Also noteworthy, is the fact that gidB mutations were only present in isolates without rpsL and rrs mutations, all from genetic cluster Q1. Streptomycin quantitative drug susceptibility testing showed that isolates carrying the gidB A80P mutation were streptomycin intermediate-level resistant and that standard drug susceptibility testing yielded inconsistent results, probably due to borderline resistance. We conclude that gidB mutations may explain the high number of streptomycin-resistant strains with no mutation in rpsL or rrs. These mutations might occasionally confer low-level streptomycin resistance that will go undetected in standard susceptibility testing.

A new universal simplified adhesive: 18-month clinical evaluation.

PURPOSE: To evaluate the 18-month clinical performance of a multimode adhesive (Scotchbond Universal Adhesive, SU, 3M ESPE, St Paul, MN, USA) in noncarious cervical lesions (NCCLs) using two evaluation criteria. MATERIALS AND METHODS: Thirty-nine patients participated in this study. Two-hundred restorations were assigned to four groups: ERm, etch-and-rinse + moist dentin; ERd, etch-and-rinse + dry dentin; Set, selective enamel etching; and SE, self-etch. The composite resin, Filtek Supreme Ultra (3M ESPE), was placed incrementally. The restorations were evaluated at baseline, and at 18 months, using both the World Dental Federation (FDI) and the United States Public Health Service (USPHS) criteria. Statistical analyses were performed using Friedman repeated-measures analysis of variance by rank and McNemar test for significance in each pair (α=0.05). RESULTS: Five restorations (SE: 3; Set: 1; and ERm: 1) were lost after 18 months (p>0.05 for either criteria). Marginal staining occurred in four and 10% of the restorations evaluated (p>0.05), respectively, for USPHS and FDI criteria. Nine restorations were scored as bravo for marginal adaptation using the USPHS criteria and 38%, 40%, 36%, and 44% for groups ERm, ERd, Set, and SE, respectively, when the FDI criteria were applied (p>0.05). However, when semiquantitative scores (or SQUACE) for marginal adaptation were used, SE resulted in a significantly greater number of restorations, with more than 30% of the total length of the interface showing marginal discrepancy (28%) in comparison with the other groups (8%, 6%, and 8%, respectively, for ERm, ERd, and Set). CONCLUSIONS: The clinical retention of the multimode adhesive at 18 months does not depend on the bonding strategy. The only differences between strategies were found for the parameter marginal adaptation, for which the FDI criteria were more sensitive than the USPHS criteria.

Immediate adhesive properties to dentin and enamel of a universal adhesive associated with a hydrophobic resin coat.

OBJECTIVES: To evaluate the effect of acid etching and application of a hydrophobic resin coat on the enamel/dentin bond strengths and degree of conversion (DC) within the hybrid layer of a universal adhesive system (G-Bond Plus [GB]). METHODS: A total of 60 extracted third molars were divided into four groups for bond-strength testing, according to the adhesive strategy: GB applied as a one-step self-etch adhesive (1-stepSE); GB applied as in 1-stepSE followed by one coat of the hydrophobic resin Heliobond (2-stepSE); GB applied as a two-step etch-and-rinse adhesive (2-stepER); GB applied as in 2-stepER followed by one coat of the hydrophobic resin Heliobond (3-stepER). There were 40 teeth used for enamel microshear bond strength (µSBS) and DC; and 20 teeth used for dentin microtensile bond strength (µTBS) and DC. After restorations were constructed, specimens were stored in water (37°C/24 h) and then tested at 0.5 mm/min (µTBS) or 1.0 mm/min (µSBS). Enamel-resin and dentin-resin interfaces from each group were evaluated for DC using micro-Raman spectroscopy. Data were analyzed with two-way analysis of variance for each substrate and the Tukey test (α=0.05). RESULTS: For enamel, the use of a hydrophobic resin coat resulted in statistically significant higher mean enamel µSBS only for the ER strategy (3-stepER vs 2-stepER, p<0.0002). DC was significantly improved for the SE strategy (p<0.00002). For dentin, the use of a hydrophobic resin coat resulted in significantly higher dentin mean µTBS only for the SE strategy (2-stepSE vs 1-stepSE, p<0.0007). DC was significantly improved in groups 2-stepSE and 3-stepER when compared with 1-stepSE and 2-stepER, respectively (p<0.0009). CONCLUSIONS: The use of a hydrophobic resin coat may be beneficial for the selective enamel etching technique, because it improves bond strengths to enamel when applied with the ER strategy and to dentin when used with the SE adhesion strategy. The application of a hydrophobic resin coat may improve DC in resin-dentin interfaces formed with either the SE or the ER strategy. On enamel, DC may benefit from the application of a hydrophobic resin coat over 1-stepSE adhesives.

Two-year clinical performance of a low-shrinkage composite in posterior restorations.

OBJECTIVES: The aim of this study was to compare the two-year clinical performance of three restorative systems in posterior restorations, which included a low-shrinkage composite and both etch-and-rinse and self-etch adhesive strategies. MATERIALS AND METHODS: After signing an informed consent, 25 patients received three Class I (occlusal) or Class II restorations performed with one of three restorative systems: Filtek Silorane Restorative System, Adper Scotchbond 1 XT (a two-step etch-and-rinse adhesive) with Filtek Z250, and Adper Scotchbond SE (a two-step self-etch adhesive) with Filtek Z250. All materials were applied following the manufacturer's instructions. Two blind observers evaluated the restorations at three different moments (baseline; and after one and two years) according to the US Public Health Service modified criteria. Kruskal-Wallis test and Mann-Whitney U-test were used to compare the behavior of the restorative systems, while Friedman and Wilcoxon tests were applied to analyze the intra-system data (p<0.05). RESULTS: The three restorative systems showed a statistically similar clinical performance at two years. Intra-system comparisons between baseline and two years showed declining marginal adaptation scores in the restorations placed with all systems. In addition, marginal staining and surface roughness scores were lower after two years for the restorations placed with Adper Scotchbond SE + Filtek Z250. CONCLUSIONS: Although the clinical performance of Filtek Silorane was considered acceptable after two years, no advantage of the silorane-based resin over the methacrylate-based composite was found. Teeth restored with Adper Scotchbond SE showed a tendency for marginal staining, which may compromise the final color of the restorations.

Effect of artificial aging and surface treatment on bond strengths to dental zirconia.

The objective of this project was to study the influence of artificial aging and surface treatment on the microtensile bond strengths (µTBS) between zirconia and a phosphate monomer-based self-adhesive cement. Thirty zirconia disks (IPS e.max ZirCAD, Ivoclar Vivadent) were randomly assigned to two aging regimens: AR, used as received, which served as a control, and AG, artificial aging to simulate low-temperature degradation. Subsequently, the disks of each aging regimen were assigned to three surface treatments: NT, no surface treatment; CO, surface silicatization with CoJet sand (3M ESPE); and ZP, zirconia surface treated with Z-Prime Plus (Bisco Inc). Thirty discs were made of Filtek Z250 (3M ESPE) composite resin and luted to the zirconia discs using RelyX Unicem (3M ESPE). The specimens were sectioned with a diamond blade in X and Y directions to obtain bonded beams with a cross-section of 1.0 ± 0.2 mm. The beams were tested in tensile mode in a universal testing machine at a speed of 0.5 mm/min to measure µTBS. Selected beams were selected for fractographic analysis under the SEM. Statistical analysis was carried out with two-way analysis of variance and Dunnett T3 post hoc test at a significance level of 95%. The mean µTBS for the three AR subgroups (AR-NT, AR-CO, and AR-ZP) were significantly higher than those of the corresponding AG groups (p<0.0001). Both AR-CO and AR-ZP resulted in statistically significant higher mean bond strengths than the group AR-NT (p<0.006 and p<0.0001, respectively). Both AG-CO and AG-ZP resulted in statistically significant higher mean bond strengths than the group AG-NT (both at p<0.0001). Overall, AG decreased mean µTBS. Under the SEM, mixed failures showed residual cement attached to the zirconia side of the beams. CO resulted in a characteristic roughness of the zirconia surface. AR-ZP was the only group for which the amount of residual cement occupied at least 50% of the interface in mixed failures.

Effect of substrate age and adhesive composition on dentin bonding.

PURPOSE: To study the effect of dentin age and adhesive composition on the microtensile dentin bond strengths (µTBS) of five dentin adhesives. MATERIALS AND METHODS: Sixty extracted caries-free human teeth were assigned to the appropriate age group: less than 21 years of age (<21), 21-40 years of age (21-40), and greater than 40 years of age (>40). For each age group, specimens were randomly divided into five dentin adhesives: (1) Adper Easy Bond (EB, 3M ESPE), a one-step self-etch adhesive; (2) Experimental Adper Easy Bond without the Vitrebond Co-polymer (CP) (EBnoCP, 3M ESPE); (3) Adper Single Bond Plus (SB, 3M ESPE), a two-step etch&rinse adhesive; (4) Experimental Adper Single Bond Plus without CP (SBnoCP, 3M ESPE); and (5) Adper Scotchbond Multi-Purpose (MP, 3M ESPE), a three-step etch&rinse adhesive, as the control group. Specimens were sectioned in X and Y directions and the resulting beams were tested to failure in tension mode at a crosshead speed of 1 mm/min. Statistical analysis was computed using t-test and two-way analysis of variance followed by Fisher least significant difference multiple comparison post hoc test at p < 0.05. RESULTS: The highest mean µTBS values were obtained in the control group (MP) for all age groups. EB resulted in statistically similar mean µTBS compared to EBnoCP for all age groups: p = 0.538 for (<21); p = 0.974 for (21-40); and p = 0.909 for (>40). SB resulted in statistically higher mean µTBS than SBnoCP for all age groups [p<0.009 for (<21); p<0.028 for (21-40); and p<0.041 for (>40)]. MP, the control group, resulted in statistically lower mean µTBS when applied to the oldest age group (>40) compared to the youngest age group (<21), at p < 0.04. When means were pooled for the variable 'age group,' SB resulted in significantly higher mean µTBS than SBnoCP at p < 0.009, while EB resulted in statistically similar mean µTBS compared to EBnoCP (p=0.9). MP resulted in statistically higher mean µTBS than all other adhesives-SB (p<0.0001), SBnoCP (p<0.0001), EBnoCP (p<0.022), and EB (p<0.046). CONCLUSIONS: The substrate age influenced the bonding ability of the three-step etch&rinse adhesive. The presence of a carboxylic-based polymer (CP) enhanced the bonding ability of the two-step etch&rinse adhesive.

Randomized clinical trial of two resin-modified glass ionomer materials: 1-year results.

With institutional review board approval, 33 patients who needed restoration of noncarious cervical lesions (NCCL) were enrolled in this study. A total of 92 NCCL were selected and randomly assigned to three groups: (1) Ambar (FGM), a two-step etch-and-rinse adhesive (control), combined with the nanofilled composite resin Filtek Supreme Plus (FSP; 3M ESPE); (2) Fuji II LC (GC America), a traditional resin-modified glass ionomer (RMGIC) restorative material; (3) Ketac Nano (3M ESPE), a nanofilled RMGIC restorative material. Restorations were evaluated at six months and one year using modified United States Public Health Service parameters. At six months after initial placement, 84 restorations (a 91.3% recall rate) were evaluated. At one year, 78 restorations (a 84.8% recall rate) were available for evaluation. The six month and one year overall retention rates were 93.1% and 92.6%, respectively, for Ambar/FSP; 100% and 100%, respectively, for Fuji II LC; and 100% and 100%, respectively, for Ketac Nano with no statistical difference between any pair of groups at each recall. Sensitivity to air decreased for all three adhesive materials from the preoperative to the postoperative stage, but the difference was not statistically significant. For Ambar/FSP, there were no statistical differences for any of the parameters from baseline to six months and from baseline to one year. For Fuji II LC, surface texture worsened significantly from baseline to six months and from baseline to one year. For Ketac Nano, enamel marginal staining increased significantly from baseline to one year and from six months to one year. Marginal adaptation was statistically worse at one year compared with baseline only for Ketac Nano. When parameters were compared for materials at each recall, Ketac Nano resulted in significantly worse color match than any of the other two materials at any evaluation period. At one year, Ketac Nano resulted in significantly worse marginal adaptation than the other two materials and worse marginal staining than Fuji II LC. Surface texture was statistically worse for Fuji II LC compared with the other two materials at all evaluation periods. The one-year retention rate was statistically similar for the three adhesive materials. Nevertheless, enamel marginal deficiencies and color mismatch were more prevalent for Ketac Nano. Surface texture of Fuji II LC restorations deteriorated quickly.

Reliability of fiber post bonding to root canal dentin after simulated clinical function in vitro.

The aim of this study was to investigate the effect of thermomechanical loading (TML) on the bond strength of fiber posts luted with three different resin cements. Sixty-six extracted human anterior teeth were endodontically treated and restored with fiber posts (RelyX Fiber Posts, 3M ESPE) using three commercially available resin cements and three corresponding core build-up materials (n=22 each): Panavia F 2.0/Clearfil DC Core Automix (Kuraray), Variolink II/Multicore Flow (Ivoclar Vivadent), and RelyX Unicem/Filtek Z250 (3M ESPE). Twelve specimens of each group received all-ceramic crowns and were subjected to TML. The other 10 specimens were stored in saline solution for 24 hours. The roots were sectioned and bond strength was measured using a push-out test. Adhesive interfaces of two specimens of each group subjected to TML were analyzed using field emission scanning electron microscopy (FESEM). Bond strengths of fiber posts were significantly affected by the type of resin cement (p<0.0005) and TML (p<0.0005; two-way analysis of variance). TML significantly reduced bond strengths for all materials ((6.0 (6.2) MPa)) compared with initial bond strengths ((14.9 (10.4) MPa)). RelyX Unicem resulted in significantly higher bond strengths before ((18.3 (10.3) MPa)) and after TML ((9.8 (7.5) MPa)) compared with the other materials (p<0.0005; Tukey HSD). Using FESEM, Variolink II and Panavia F demonstrated a hybrid layer partly detached from the underlying resin cement, whereas no hybrid layer was observed for RelyX Unicem. The decrease in bond strength after TML suggests that retention of fiber posts may be reduced after clinical function. Therefore, endodontically treated teeth that are restored using fiber posts may benefit from additional reinforcement via coronal restorations using adequate ferrules and/or adhesive techniques.

Clinical evaluation of a low-shrinkage composite in posterior restorations: one-year results.

OBJECTIVES: The aim of this study was to compare the one-year clinical performance of three restorative systems, which included a novel low-shrinkage composite and two bonding strategies. MATERIALS AND METHODS: Twenty-five patients received three Class I (occlusal) or Class II restorations performed with one of three restorative systems: Filtek Silorane Restorative System (FS); Adper Scotchbond 1 XT, a two-step etch-and-rinse adhesive, with Filtek Z250 (XT); and Adper Scotchbond SE, a two-step self-etch adhesive, with Filtek Z250 (SE). All materials were applied following the manufacturer's instructions. Two independent observers evaluated the restorations at baseline, after six months, and after one year, according to the United States Public Health System modified criteria. The Kruskal-Wallis test and the Mann-Whitney U-test were computed to compare the behavior of the restorative systems; Friedman and Wilcoxon tests were used to analyze the intrasystem data (α=0.05). RESULTS: All restorations were evaluated at one year. FS and XT performed statistically similarly at one year, but marginal staining for SE was statistically worse. Intrasystem comparisons between baseline and one year also showed deterioration of marginal staining for SE, while a deterioration of the marginal adaptation was recorded for both SE and FS. XT was the only system for which there was no statistical change of the parameters measured in this study. CONCLUSIONS: Both restorative systems using self-etch adhesives showed a tendency to degradation of marginal adaptation after one year of clinical use, compared to baseline values. Although the clinical performance of FS was deemed acceptable after one year, this study did not find any advantage of the silorane-based composite over the methacrylate-based composite. The low-shrinkage associated with FS may not be a determinant factor for clinical success.

Randomized clinical trial of four adhesion strategies: 18-month results.

STATEMENT OF THE PROBLEM: With Institutional Review Board approval, 39 patients who needed restoration of noncarious cervical lesions (NCCLs) were enrolled in this study. A total of 125 NCCLs were selected and randomly assigned to four groups: 1) a three-step etch-and-rinse adhesive, Adper Scotchbond Multi-Purpose (MP, 3M ESPE, St Paul, MN, USA); 2) a two-step etch-and-rinse adhesive, Adper Single Bond Plus (SB, 3M ESPE); 3) a two-step self-etch adhesive, Adper Scotchbond SE (SE, 3M ESPE); and 4) a one-step self-etch adhesive, Adper Easy Bond (EB, 3M ESPE). A nanofilled composite resin was used for all restorations. Restorations were evaluated at six months and 18 months using modified U.S. Public Health Service (USPHS) parameters. RESULTS: At six months after initial placement, 107 restorations (85.6% recall rate) were evaluated. At 18 months, 94 restorations (75.2% recall rate) were available for evaluation. The 6 mo/18 mo overall retention rates (%) were 100/90.9 for MP; 100/91.7 for SB; 100/90.9 for SE; and 96.4/92.3 for EB with no statistical difference between any pair of groups at each recall. Sensitivity to air decreased significantly for all adhesives from the preoperative to the postoperative stage and was stable thereafter. Interfacial staining did not change statistically from baseline to six months; however, interfacial staining at the enamel margins was statistically worse at 18 months than at baseline for the two self-etch adhesives EB and SE. Marginal adaptation was statistically worse at 18 months compared with baseline only for EB. This tendency was already significant at the six-month recall. CONCLUSION: Although 18-month retention was similar for the different adhesion strategies, enamel marginal deficiencies were more prevalent for the self-etch adhesives.

Tuberculosis drug-resistance in Lisbon, Portugal: a 6-year overview.

Multidrug-resistance and extensive drug-resistance pose a serious threat to tuberculosis management in Portugal. The country has high TB incidence rates in comparison with other European Union countries, with the Lisbon Health Region being one of the most affected. In the present study we have analysed a convenience sample of 3025 Mycobacterium tuberculosis clinical isolates, recovered over a 6-year period (2001-2006) in the Lisbon Health Region, regarding drug-resistance both to first-line and second-line drugs. Moreover, 100 of these isolates were also genotyped by 12-loci Mycobacterial Interspersed Repetitive Unit - Variable Number of Tandem Repeats (MIRU-VNTR) analysis. We have compared each year and observed the existence of 22 different resistance profiles, with MDR-TB rates ranging between 9.9% and 15.2% and XDR-TB rates, relative to the number of MDR-TB isolates, between 44.3% and 66.1% (excluding 1 year here considered as an outlier). A steady increase in the fraction of MDR-TB isolates resistant to all first-line drugs was also noticed. The genotyping analysis of MDR-TB isolates revealed six clusters, of which three (Lisboa3, Lisboa4 and Q1) were related to XDR-TB. Our results show that active transmission of MDR- and XDR-TB is taking place and that the high prevalence of observed XDR-TB is due to the continued transmission of particular genetic clusters. Enforcement of the implementation of genotyping in diagnostic routines would lead to early detection of resistant cases.

Bond strength and nanoroughness assessment on human pretreated cementum surfaces.

OBJECTIVES: To determine the bond strength of seven adhesive systems to human cementum, and to assess the promoted surface roughness. METHODS: Extracted human canines were used for the present study. The mesial surface from the cervical third of the roots were ground flat with wet 600-grit silicon carbide paper and bonded. Seven adhesive systems were employed: an etch-and-rinse adhesive (Single Bond), two two-step self-etching (Clearfil SE Bond and Resulcin Aquaprime) and four one-step self-etching (One-up Bond F, Prompt-L-Pop, Etch and Prime 3.0 and NRC+Prime&Bond NT). Composite build-ups were constructed and stored in a humid environment for 24h at 37 degrees C. Specimens were sectioned into 1mm(2) beams and tested for microtensile bond strength (MTBS). Additional surfaces were conditioned for atomic force microscopy (AFM) analysis. Results were analyzed with ANOVA and Student-Newman-Keuls tests (P<0.05). RESULTS: Single Bond showed the highest MTBS values. No differences were found between Resulcin Aquaprime, One-up Bond and Prompt-L-Pop. Clearfil SE Bond, Etch and Prime and NRC+Prime&Bond NT obtained the lowest bond strength values. H(3)PO(4) acid treatment of cementum and Resulcin Aquaprime showed the highest nanoroughness parameters and One-up Bond the lowest. CONCLUSION: The etch-and-rinse adhesive and the two-step self-etching adhesive with the lowest pH value promoted the highest bond strength to human cementum surfaces.

Microtensile adhesion of sealants to intact enamel.

UNLABELLED: Contamination of etched enamel with saliva has been shown to result in sealant failure. Hydrophilic adhesives improve retention of sealants when enamel is contaminated. OBJECTIVE: The objective of the present study was to characterize the adhesion of two sealants to unprepared enamel etched with phosphoric acid or conditioned with the all-in-one, self-etch adhesive Adper Prompt L-Pop. METHODS: The two proximal enamel surfaces of 16 sound molars were assigned to four conditioning regimens: (1) 35% phosphoric acid for 15 s; (2) Adper Prompt L-Pop, one layer light-cured prior to sealant placement; (3) Adper Prompt L-Pop, two layers light-cured prior to sealant placement; and (4) Adper Prompt L-Pop, one layer co-cured with sealant. One of two sealants, i.e. Clinpro or Delton DDS, was applied, light-cured, followed by a composite build-up to provide support for microtensile bond testing. RESULTS: The highest mean bond strengths were obtained when Adper Prompt L-Pop was applied in two layers and light-cured prior to the insertion of Clinpro Sealant. Co-cure of Adper Prompt L-Pop with either sealant resulted in bond strengths which were not significantly different from those of the phosphoric acid control. The use of Adper Prompt L-Pop in one layer cured prior to sealant placement resulted in statistically lower bond strengths than any other application technique regardless of the sealant used. Clinpro Sealant resulted in statistically higher bond strengths than Delton DDS Sealant. CONCLUSIONS: Application of one layer of Adper Prompt L-Pop co-cured with the sealant resulted in bond strengths similar to those obtained with phosphoric acid etching.