Wetting ability of an acetone/based etch&rinse adhesive after NaOCl-treatment

Does the Type of Solvent in Dental Adhesives Influence the Clinical Performance of Composite Restorations Placed in Noncarious Cervical Lesions? A Systematic Review and Meta-analysis

CLINICAL RELEVANCE

According to the clinical and scientific evidence presented in this systematic review and meta-analysis, dental adhesives containing either organic solvent (acetone or alcohol) can be used to achieve similar clinical performance and longevity of composite restorations.

SUMMARY

Objectives: This systematic review and meta-analysis compared the clinical performance and survival rates of composite restorations placed in noncarious cervical lesions (NCCLs) using dental adhesives containing acetone or alcohol-based solvents.Methods and Materials: PubMed, Scopus, Web of Science, Virtual Health Library (VHL) LILACS, Cochrane Library, OpenGrey, Clinical Trials, and Rebec were searched. MeSH terms, supplementary concepts, synonyms, and free keywords were used in the search strategy. All references were crosschecked by two independent investigators following the PICOS strategy (population, NCCLs; intervention, acetone-based bonding agent; comparison, alcohol-based bonding agent; outcome, clinical evaluation parameters and survival rates; study design, randomized controlled clinical trials). Cochrane Collaboration's tool was used to assess risk of bias, and two distinct meta-analyses were performed using the RevMan software. The prevalence of success and the total number of restorations for each group (acetone- or alcohol-based) were used to calculate the risk difference at a confidence interval of 95%. Random-effects models were applied, and heterogeneity was assessed using the I2 index in the pooled and subgrouped meta-analyses. The certainty of evidence was evaluated through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.Results: A total of 7876 studies were retrieved, from which 27 studies were selected for the systematic review. Ten studies were classified as "low risk of bias" and included in the meta-analyses. Overall heterogeneity was not significant (I2 = 0.00%). The clinical performance of restorations placed with bonding agents based on both solvents for each of the available parameters presented no statistical significance for any of the meta-analyses (p>0.05).Conclusion: Scientific evidence suggests composite restorations placed with acetone or alcohol-based dental adhesives present similar clinical performance and survival rates in NCCLs.

Dry-bonding to dentin using alternative conditioners based on iron-containing solutions or nitric acid

OBJECTIVES

To evaluate the effect of experimental conditioners (10-3 solution - 10-3, 6.8% ferric oxalate - FOX, and 1.4% nitric acid - NI) on dentin elastic modulus, flexural strength, bond strength, failure mode, and adhesive interface morphology of two etch-and-rinse adhesives (XP Bond, Dentsply or One-Step, Bisco) applied on etched dry dentin.

METHODS

Sound human third molars were used for the microtensile bond strength test (n = 8), performed at 24 h and after one year of water storage. Failure modes were evaluated by scanning electron microscopy. Dentin bonding interface was analyzed by confocal laser scanning microscopy (n = 3). Adhesive systems were applied on phosphoric acid-etched, wet (positive control) and dry (negative control) dentin, and on etched and dry dentin previously treated with 10-3 (15s), FOX (60s), or NI (15s). Bovine dentin bars (n = 15) were immersed into the conditioning solutions and subjected to a three-point bending test.

RESULTS

XP Bond + 10-3 or NI resulted in lower bond strength than phosphoric acid. One-Step + 10-3 or NI resulted in bond strengths equivalent to the positive control. Experimental conditioners presented no bond strength reduction after one year, regardless of the bonding agent tested. One-Step resulted in more adhesive failures than XP Bond at 24 h, and mixed failures increased after storage. All experimental conditioners promoted hybridization and resin tags formation, except FOX. Dentin elastic modulus was not affected by the conditioners, whereas flexural strength was significantly reduced by FOX.

CONCLUSIONS

Adequate and stable dentin bonds were achieved when the bonding agents were applied on 10-3 or NI-treated dentin. None of the experimental conditioners reduced dentin elastic modulus, but dentin flexural strength was significantly reduced by FOX-conditioning.

Effect of Collagen Matrix Saturation on the Surface Free Energy of Dentin using Different Agents

INTRODUCTION

The surface free energy of conditioned-dentin is one of the factors that interfere with monomeric infiltration of the interfibrillar spaces. Saturation of the tooth matrix with different substances may modulate this energy and, consequently, the wettability of the dentin.

AIM

To evaluate the influence of different substances used to saturate conditioned-dentin on surface free energy (SFE) of this substrate.

MATERIALS AND METHODS

Dentin blocks (4 × 7 × 1 mm, n = 6/ group), obtained from the roots of bovine incisors, were etched using phosphoric acid for 15 seconds, rinsed and gently dried. The surfaces were treated for 60 seconds with: ultra-purified water (H20-control); ethanol (EtOH), acetone (ACT), chlorhexidine (CHX), ethylenediaminetetraacetic acid (EDTA); or sodium hypochlorite (NaOCl). The tooth surfaces were once again dried with absorbent paper and prepared for SFE evaluation using three standards: water, formamide and bromonaphthalene. Analysis of variance (ANOVA) and Dunnet's tests (a = 0.05) were applied to the data.

RESULTS

Ethylenediaminetetraacetic acid was the only substance that caused a change to the contact angle for the standards water and formamide, while only EtOH influenced the angles formed between formamide and the dentin surface. None of the substances exerted a significant effect for bromonaphtha-lene. In comparison to the control, only EDTA and NaOCl altered both polar components of the SFE. Total SFE was increased by saturation of the collagen matrix by EDTA and reduced when NaOCl was used.

CONCLUSION

Saturation of the collagen matrix by EDTA and EtOH changed the surface free energy of the dentin. In addition, the use of NaOCl negatively interfered with the properties evaluated.

CLINICAL SIGNIFICANCE

The increase of surface free energy and wettability of the dentin surface would allow higher penetration of the the adhesive system, which would be of importance to the clinical success of resin-dentin union.

Bonding efficacy of an acetone/based etch-and-rinse adhesive after dentin deproteinization

Objectives: to evaluate the effect of sodium hypochlorite (NaOCl) treatment on dentin bonding by means of shear bond strength (SBS) measurements when using Prime&Bond NT (PB NT) adhesive. Ultrastructure of the interfaces was examined by scanning electron microscopy (SEM). Study design: Extracted human third molars were sectioned and ground to expose flat surfaces of superficial or deep dentin. Specimens were randomly assigned to two equal groups, and bonded as follows: (1) according to the manufacturers’ directions, after 35% H3PO4 etching, (2) 5% NaOCl treated for 2 minutes, after 35% H3PO4 etching. Each sample was embedded in a Watanabe shear test assembly for a single plane lap shear. After PB NT bonding, specimens were stored in water for 24 h at 37ºC and thermocycled (500x). Samples were tested in shear to failure using a universal testing machine at 0.75 mm/min. Data were analyzed with ANOVA and Newman-Keuls multiple comparison test procedures. Two samples of each group were randomly selected to investigate the morphologic aspect of the resin/dentin interface with SEM. Results: After etching and after aqueous sodium hypochlorite (NaOClaq) application, SBS values were similar on superficial than deep dentin (p>0.05). SEM findings shows for H3PO4 etching conditioned samples a detectable hybrid layer and long resin tags; for NaOCl treated specimens, it may be observed a non apparent hybrid layer, and the adhesive contact directly with the neck of the cylindrical resin tags. Conclusions: The use of 5% NaOCl for 2 min after dentin demineralization when PB NT was employed did not improve the bond strength to dentin, probably due to nanofiller content and/or oxidative changes on collagen-depleted dentin.

Key words:Sodium hypochlorite, shear bond strength, SEM, Prime&Bond NT, superficial dentin, deep dentin.