Operator versus material influence on film thickness using adhesive resin cement or pre-heated resin composite.

OBJECTIVE: There is a growing interest in using pre-heated composites instead of dual-cured cements when luting indirect restorations. This study evaluated the film thickness obtained from two pre-heated composites and two resin cements, by two different operators. The influence of the materials and the level of expertise of the operator were analyzed. MATERIALS AND METHODS: Forty specimens of human dentin and composite discs were prepared and divided into four groups depending on the luting process. Each group was randomly equally divided to be handled by two operators with different levels of experience. Two of the initial four groups were luted using dual-cured cements and the two remaining groups using light-cured pre-heated composites. Specimen discs were cut after luting, and film thickness was measured using a Digital microscope. Data were analyzed using a 2-way ANOVA with the Holm-Sidak pairwise multiple comparison procedure (p < 0.05). RESULTS: Mean film thickness ranged from 156.16 ± 4.7 to 33.82 ± 0.7 µm. Significant differences (p < 0.001) were noticed between expert and novice results with pre-heated composites. CONCLUSION: Within the limits of this study, using pre-heated composites as a luting cement requires a better level of expertise to achieve a clinically acceptable film thickness. CLINICAL SIGNIFICANCE: Using pre-heated composites as luting agent for indirect restorations requires an experimented skill level to achieve a clinically recommended film thickness.

Treatment of Tooth Wear Using Direct or Indirect Restorations: A Systematic Review of Clinical Studies.

Tooth wear is considered a well-developed issue in daily clinical practice; however, there is no standard protocol for treatment. The aim of this manuscript was to systematically review the literature to evaluate the clinical outcomes of direct or indirect restorations for treating tooth wear. A literature search was conducted through the PubMed MedLine, Scopus, ISI Web of Science, Scielo, and EMBASE databases up to 29 April 2022. Clinical studies evaluating the clinical performance of direct or indirect restorations for treating tooth wear for a minimum follow-up of 6 months were included in the review. A total of 2776 records were obtained from the search databases. After full-text reading, 16 studies were included in the qualitative analysis. Considering the high heterogenicity of the studies included, a meta-analysis could not be performed. All studies included the rehabilitation of anterior and posterior teeth with extensive wear, using both indirect and direct restorations for a maximum follow-up of 10 years. Restoration materials included ceramo-metal crowns, full gold crowns, lithium disilicate ceramic, zirconia, polymer infiltrated ceramic networks, and resin composites. Most of the reports assessed the survival rate of the restorations and the clinical features using the United States Public Health Service (USPHS) Evaluation System criteria. Contradictory discoveries were perceived concerning the type of restoration with better clinical performance. Considering the current literature available, there is no evidence in the superiority of any restoration technique to ensure the highest clinical performance for treating tooth wear.

Does Etching of the Enamel with the Rubbing Technique Promote the Bond Strength of a Universal Adhesive System?

AIM: The aim of this in vitro research was to study the effect of etching by phosphoric acid with rubbing technique on the shear bond strength (SBS) of adhesive universal to enamel. MATERIALS AND METHODS: Sixty extracted teeth were obtained. Three application methods (self-etch, etch-and-rinse, and etch-and-rinse with rubbing technique) were performed to bond the enamel surfaces by a universal adhesive. After 24 hours of immersion in water at 37°C, the specimens were prepared for the SBS test. Scanning electron microscopy was performed to observe the adhesive-enamel interfaces. Optical numeric microscope was used to observe the failure style. Statistical analyses were done with one-way analysis of variance test. RESULTS: Statistically significant higher bond strength values were observed for etch-and-rinse mode with rubbing technique (25.98 ± 5.70) MPa then for the etch-and-rinse without rubbing (22.07 ± 5.27) MPa and self-etch modes (9.96 ± 2.98) MPa. CONCLUSION: Enamel etched by 37% phosphoric acid with rubbing technique for 20 seconds showed an increase in the SBS of the universal adhesive to enamel surfaces. The tags of the adhesive can be presented more efficiently by rubbing the acid before the bonding process, consequently, an optimal interface for the bonding. CLINICAL SIGNIFICANCE: According to the results of this in vitro study, the selective enamel etching mode with rubbing technique is advisable when using the universal adhesive, as it significantly increased the bond strength of this adhesive to enamel surfaces. The clinician should etch the enamel using phosphoric acid with rubbing technique for 20 seconds to promote the bond strength of the universal adhesive system.

Effect of etching the coronal dentin with the rubbing technique on the microtensile bond strength of a universal adhesive system.

BACKGROUND: The adhesion of composite resins to the dentin substrate is influenced by the treatment of the smear layer. While etch-and-rinse systems require dentin to be conditioned with phosphoric acid, self-etching systems preserve the smear layer by incorporating it into the adhesive layer. OBJECTIVES: The objective of this study was to evaluate the influence of etching with the rubbing technique on the microtensile bond strength (µTBS) of a universal adhesive to dentin. MATERIAL AND METHODS: Eighteen extracted teeth were selected. Two etch-and-rinse techniques (with and without rubbing) and a self-etching technique were used to bond the dentin surfaces with a universal adhesive system. After 24 h, the bonded samples were prepared for the µTBS testing. The specimens were loaded with a tensile force at a crosshead speed of 0.5 mm/min until failure. The scanning electron microscope (SEM) analyses were used to reveal the failure modes. The data were statistically analyzed with the one-way analysis of variance (ANOVA) and χ2 tests. RESULTS: The etch-and-rinse system with rubbing produced significantly lower bond strength (42.11 ±9.26 MPa,) than the etch-and-rinse system without rubbing (47.30 ±8.12 MPa) and significantly higher bond strength than the self-etching system (38.07 ±9.49 MPa). CONCLUSIONS: Under the conditions of this study, dentin etched with phosphoric acid for 3 s in the etchandrinse mode with the rubbing technique for a universal adhesive system decreases the µTBS of the composite to dentin.

A modified inside/outside bleaching technique for nonvital discolored teeth: a case report.

Over the past decades, the walking bleach technique using sodium perborate was considered a safe and effective method to bleach nonvital discolored teeth. However, sodium perborate has been classified as carcinogenic, mutagenic, and toxic for reproduction by European Union legislation. Its use is therefore prohibited since April 2015. The initially described inside/outside bleaching technique, combining internal and external application of 10% carbamide peroxide, is an alternative to the walking bleach technique using sodium perborate. While good esthetic results and low risks of external cervical resorptions have been associated with this technique, its main drawback is that the access cavity is left open. To overcome this disadvantage, the present authors propose to seal the bleaching agent in the access cavity instead of leaving the latter open. Through a clinical case, this paper presents and discusses several aspects of this protocol, including the clinical steps, the design of the bleaching tray, and the treatment of potential recurrences. The present authors believe that the protocol proposed in this article is easier to use for the patient. Moreover, it prevents the accumulation of food debris in the access cavity and avoids the colonization of coronary dentin by bacteria.

Polyphenols at interfaces.

Polyphenols are important molecules in living organisms, particularly in plants, where they serve as protectants against predators. They are also of fundamental importance in pharmacology for their antioxidant and antibacterial activities. Since a few years polyphenols are also used in surface functionalization mimicking the tannin deposition observed when tea or red wine are in contact with the surface of cups or glasses respectively. The interaction of polyphenols with proteins to yield colloids and of polyphenol with surfaces will be reviewed in this article to provide an overview of such particles and surface functionalization methods in modern surface science. Particular emphasis will be given to biological applications of polyphenols at interfaces.