Bonding Strength of Universal Adhesives To Er,Cr:YSGG Laser-Irradiated Dentin

Objectives: Universal adhesives have been recently introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinical condition. However, their bonding effectiveness to laser-irradiated dentin is still not well known. Therefore, the aim of this study was to compare the shear bond strength (SBS) of two universal adhesives (Single Bond Universal, Nova Compo-B Plus) applied following laser-etching with SBS of the same adhesives applied in selfetch and acid-etch modes, respectively. Materials and Methods: Sixty bovine incisors were used to obtain the flattened dentin surfaces. Specimens were divided into two groups according to universal adhesives. Each universal adhesive was applied with one of the following modes, self-etch, acid-etch, or laser-etch (n = 10). Er,Cr:YSGG laser was used for laser-etching with 1.5 W–20 Hz parameters. After adhesive applications and composite buildups, SBS was determined after storage in water for 24 h using a universal testing machine with a crosshead speed of 0.5 mm/min. Failure modes were evaluated using a stereomicroscope. Data were analyzed using two-way of analyses of variances (ANOVA) (P = 0.05). Results: Two-way ANOVA revealed that adhesive had no effect on SBS (P > 0.05), but application mode significantly influenced SBS (P < 0.001). Laser-etch significantly increased SBS for NCP when compared to self-etch mode, whereas laser-etch provided similar SBS with self-etch mode for SBU. Conclusions: The influence of different application modes on dentin bond strength of universal adhesives was dependent on the adhesive material. Clinical Significance: For universal adhesives, laser etching may provide some benefits on bonds strength but this would depend on product.Keywords: Adhesion, bonding, dentin, laser, universal adhesive

Radiopacity of bulk fill flowable resin composite materials

Objectives: The purpose of this study was to evaluate the radiopacity of currently marketed bulk fill flowable dental composite materials (Beautifil Bulk Flowable, SDR Flow, Filtek Bulk Fill Flow, and x‑tra Base Bulk Fill).Materials and Methods: Six specimens of each material with a thickness of 1 mm were prepared, and digital radiographs were taken, using a CCD sensor along with an aluminum stepwedge and 1 mm‑thick tooth slice. The mean gray level of each aluminum stepwedge and selected materials was measured, using the equal‑density area tool of Kodak Dental Imaging software. The equivalent thickness of aluminum for each material was then calculated by using the stepwedge values in the CurveExpert version 1.4 program.Results: The radiopacity of bulk fill flowable composites sorted in descending order as follows: Beautifil Bulk Flowable (2.96 mm Al) = x‑tra base bulk fill (2.92 mm Al) = SureFil SDR Flow (2.89 mm Al) > Filtek Bulk Fill Flow (2.51 mm Al) (P < 0.05).Conclusions: As all materials had a radiopacity greater than dentin and enamel; their adequate radiopacity will help the clinicians during radiographic examination of restorations.Clinical Significance: Bulk fill composite materials have greater radiopacity, enabling clinicians to distinguish the bulk fill composites from dentin and enamel.Key words: Bulk‑fill flowable, composite, radiopacit