Adhesive Systems as an Alternative Material for Color Masking of White Spot Lesions: Do They Work?

PURPOSE: To evaluate the color masking effect of infiltration treatment of artificial white spot lesions (AWSL) using a dedicated resin in comparison to different adhesive systems. MATERIALS AND METHODS: Enamel/dentin specimens were obtained from bovine incisors and baseline color was assessed using a reflectance spectrophotometer, according to the CIE L*a*b* system. AWSL were produced using a buffered acid solution and a new color evaluation was performed. The specimens were divided into 8 groups: control: artificial saliva changed daily for 7 days; IC: infiltrating resin Icon; EC: EquiaCoat; FU: Futurabond U; SBU: Single Bond U; SBMP: Scotchbond MP; OB: OptibondFL; BF: Bioforty. After the treatments, the color was evaluated again and the values for the parameters ΔL (change in lightness), Δa (change in chroma), Δb (change in hue), and ΔE (general color difference) were calculated in relation to baseline. Data were analyzed by one-way ANOVA and Tukey's tests. RESULTS: After treatment, ANOVA showed significant differences for all parameters (p = 0.001). Tukey's test showed the greatest lightness reduction (ΔL) for the IC group, followed by EC, FU, and SBU. The SBMP, OB, and BF groups were similar to the control. For Δb values, all groups showed differences in relation to the control, with no differences between them. In relation to ΔE, all groups showed differences in relation to the control (ΔE = 5.24), with no significant differences between them. ΔE values after application of all resinous materials were lower than the threshold of 3.7, indicating effective color masking. CONCLUSIONS: The Icon infiltrant produced a greater lightness reduction of white lesions (ΔL). For general color difference (ΔE), all the resinous materials tested were able to color mask artificial AWSL.

Flowable bulk-fill versus layering restorative material on Class II restorations: A randomized clinical trial.

OBJECTIVE: This study evaluated the clinical performance of Class II restorations made with flowable bulk-fill base versus conventional layering ORMOCER-based restorative material in a split-mouth randomized clinical trial. METHODS: Thirty patients received two class II restorations (n = 60) performed with different strategies. All preparations received the application of the universal self-etching adhesive system according to the manufacturer's recommendation, followed by the placement of a sectional matrix, wooden wedge, and separation ring. The first restoration was performed using 4 mm of flowable bulk-fill material covered by 2 mm of conventional viscosity restorative material (Bulk-fill technique). The second restoration was performed only with the conventional viscosity material, with a maximum of 2 mm thick increments, up to fill the cavity (Layering technique). After occlusal adjustment, the same polishing system was used for all restorations. Evaluations using the FDI criteria were conducted after 7 days, 12, and 24 months. Data were analyzed with the Fisher's Exact test (α=0.05). RESULTS: From 30 participants, 24 attended the 24-month recall, and 48 restorations were evaluated. All restorations received acceptable overall scores for esthetic and biological properties after this period, while only 6.66 % of the restorations exhibited unacceptable overall scores for the functional properties in both groups. No significant differences between the tested restorative materials and techniques were found for each FDI criterion assessed. The success rate after 2 years was 93.33 % for both groups. CONCLUSION: Both restorative materials exhibited good clinical performance for the parameters analyzed with no differences between them after 24-month follow-up. CLINICAL RELEVANCE: Flowable bulk-fill ORMOCER-based material is a suitable alternative for direct Class II restorations, providing good clinical outcomes and simplifying the restorative procedure. CLINICAL TRIAL REGISTRATION NUMBER: RBR-6mvp9w.

Effect of Lining Materials on Shear Bond Strength for Composite Restorations In Vitro.

This study evaluated the influence of liner agents placed under resin composite restorations on shear bond strength (SBS) to dentin. A total of 40 extracted bovine incisors were used. Enamel surfaces were ground to expose a flat dentin area of 7 mm in diameter. Teeth were divided into four groups according to tested liners: Group 1 (control) used no liner; Group 2 used a resin-modified glass-ionomer cement liner (Vitrebond Plus, 3M ESPE); Group 3 used a light-activated calcium hydroxide resin liner (Ultra-Blend Plus, Ultradent); and Group 4 used a polyacrylic acid surface treatment + conventional glass-ionomer cement liner (Vidrion F, SSWhite). All groups were subjected to bonding procedures with Single Bond (3M ESPE) and 4-mm-thick buildups of resin composite were fabricated. Artificial aging was performed, and the specimens were submitted to mechanical shear testing. One-way analysis of variance (ANOVA) revealed significant differences among liners (P = .00). Group 4 showed the highest SBS. Group 1 showed significantly higher mean SBS compared with Group 3. Results showed that SBS is improved when using polyacrylic acid surface treatment + conventional glass-ionomer cement and decreased when using light-activated calcium hydroxide when compared with no liner. Polyacrylic acid surface treatment + conventional glass-ionomer cement as a liner placed under adhesion surface can improve the shear bond strength between dentin and resin, while light-activated calcium hydroxide resin should be used restrictedly in very deep cavities, because they may reduce the bond strength of the restoration submitted to masticatory forces and temperature changes in the oral environment.