Erosive cola-based drinks affect the bonding to enamel surface: an in vitro study

Objective: This study aimed to assess the impact of in vitro erosion provoked by different cola-based drinks (Coke types), associated or not with toothbrushing, to bonding to enamel. Material and methods: Forty-six bovine enamel specimens were prepared and randomly assigned into seven groups (N=8): C- Control (neither eroded nor abraded), ERO-RC: 3x/1-minute immersion in Regular Coke (RC), ERO-LC: 3x/1-minute immersion in Light Coke (LC), ERO-ZC: 3x/1-minute immersion in Zero Coke (ZC) and three other eroded groups, subsequently abraded for 1-minute toothbrushing (EROAB-RC, EROAB-LC and EROAB-ZC, respectively). After challenges, they were stored overnight in artificial saliva for a total of 24 hours and restored with Adper Single Bond 2/Filtek Z350. Buildup coronal surfaces were cut in 1 mm2 -specimens and subjected to a microtensile test. Data were statistically analyzed by two-way ANOVA/Bonferroni tests (α=0.05). Failure modes were assessed by optical microscopy (X40). The Interface of the restorations were observed using Confocal Laser Scanning Microscopy (CLSM). Results: All tested cola-based drinks significantly reduced the bond strength, which was also observed in the analyses of interfaces. Toothbrushing did not have any impact on the bond strength. CLSM showed that except for Zero Coke, all eroded specimens resulted in irregular hybrid layer formation. Conclusions: All cola-based drinks reduced the bond strength. Different patterns of hybrid layers were obtained revealing their impact, except for ZC

Effect of a New Method to Simulate Pulpal Pressure on Bond Strength and Nano leakage of Dental Adhesives to Dentin

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Purpose: To evaluate a new method of simulated pulpal pressure in vitro in comparison with the conventional one. Materials and Methods: Four adhesives were analyzed: a three-step etch-and-rinse (Scotchbond Multi-Purpose [SBMP]), a two-step etch-and-rinse (Single Bond 2 [SB]), a two-step self-etching (Clearfil SE Bond [SE]) and a one-step self-etching (Clearfil S3 [S3]) system. Restorations were built up in flat, deep dentin from extracted molars. After two methods of simulated pulpal pressure or no pulpal pressure (control groups), the samples were cut into sticks and submitted to microtensile bond strength (mu TBS) testing and nanoleakage evaluation. Results were analyzed with two-way ANOVA and Tukey's test (p<0.05). Results: In general, statistical analysis of mu TBS showed SBMP>SB=SE>S3. For both methods of simulated pulpal pressure, the mu TBS of SB and S3 was lower than in control groups. For SBMP and SE, the mu TBS remained stable with simulated pulpal pressure. Conventional and experimental methods of simulating pulpal pressure resulted in similar mu TBS (p = 1.00) and nanoleakage patterns. Silver impregnation was higher with SB and S3, especially after simulated pulpal pressure with both methods. Conclusion: The experimental simulated pulpal-pressure method tested here was similar to the conventional method and can be an alternative to it. The simplified adhesives show reduction in bond strength after simulated pulpal pressure. The multistep adhesives have stable bond strengths under simulated pulpal pressure. Therefore, the separate application of hydrophobic resin can achieve resistance to bonding deterioration after hydrostatic pressure.146517524Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Halogen and LED light curing of composite: Temperature increase and Knoop hardness

This study assessed the Knoop hardness and temperature increase provided by three light curing units when using (1) the manufacturers' recommended times of photo-activation and (2) standardizing total energy density. One halogen - XL2500 (3M/ESPE) - and two light-emitting diode (LED) curing units - Freelight (3M/ESPE) and Ultrablue IS (DMC) - were used. A type-K thermocouple registered the temperature change produced by the composite photo-activation in a mold. Twenty-four hours after the photo-activation procedures, the composite specimens were submitted to a hardness test. Both temperature increase and hardness data were submitted to ANOVA and Tukey's test (5% significance). Using the first set of photo-activation conditions, the halogen unit produced a statistically higher temperature increase than did both LED units, and the Freelight LED resulted in a lower hardness than did the other curing units. When applying the second set of photo-activation conditions, the two LED units produced statistically greater temperature increase than did the halogen unit, whereas there were no statistical differences in hardness among the curing units.101667

Hydrolytic degradation of the resin-dentine interface induced by the simulated pulpal pressure, direct and indirect water ageing

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Objectives: The aim of this study was to compare the hydrolytic effects induced by simulated pulpal pressure, direct or indirect water exposure within the resin-dentine interfaces created with three "simplified'' resin bonding systems (RBSs). Methods: A two-step/self-etching (CSE: Clearfil SE Bond), one-step/self-etching (S3: Clearfil S3) and etch-and-rinse/self-priming (SB: Single-bond 2) adhesives were applied onto dentine and submitted to three different prolonged (6 or 12 months) ageing strategies: (i) Simulated Pulpal Pressure (SPP); (ii) Indirect Water Exposure (IWE: intact bonded-teeth); (iii) Direct Water Exposure (DWE: resin-dentine sticks). Control and aged specimens were submitted to microtensile bond strength (mu TBS) and nanoleakage evaluation. Water sorption (WS) survey was also performed on resin disks. Results were analysed with two-way ANOVA and Tukey's test (p 0.05) and no evident change in nanoleakage. Conversely, SPP induced a clear formation of "water-trees'' in CS3 and SB. WS outcomes were CS3 > SB = CSE. Conclusion: The hydrolytic degradation of resin-dentine interfaces depend upon the type of the in vitro ageing strategy employed in the experimental design. Direct water exposure remains the quickest method to age the resin-dentine bonds. However, the use of SPP may better simulate the in vivo scenario. However, the application of a separate hydrophobic solvent-free adhesive layer may reduce the hydrolytic degradation and increase the longevity of resin-dentine interfaces created with simplified adhesives. (C) 2012 Elsevier Ltd. All rights reserved.401211341143Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)National Institute for Health Research under the Comprehensive Biomedical Research Centre at Guy's & St. Thomas' TrustCentre of Excellence in Medical EngineeringWellcome TrustCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Knoop hardness of dental resin cements: Effect of veneering material and light curing methods

This study evaluated the Knoop hardness of one resin cement (dual-cure mode or light-cure mode) when illuminated directly or through restorative materials-ceramic (HeraCeram) or composite (Artglass)-by two light curing units. Light curing was carried out using a conventional quartz tungsten halogen (QTH) light source (XL2500) for 40 s, and a light emitting diodes (LED) light source (Ultrablue Is) for 40 s. Bovine incisors had their buccal faces flattened and hybridised. On these surfaces, a mould was seated and filled with cement. A disc of the veneering material (1.5 mm thickness) was positioned over this set for light curing. After storage (24 h/37 degrees C), samples (n = 10) were sectioned for hardness (KHN) measurements. Data were submitted to ANOVA and to Tukey's test (alpha = 0.05). In general, light curing with LED resulted in higher hardness values than QTH. Distinct cement behaviour was observed with different veneering material in association with different light curing units (LCUs). (C) 2006 Elsevier Ltd. All rights reserved.26226827