We aimed to evaluate the color stability of bulk-fill and conventional composite resin with respect to thickness and storage media. Twenty specimens of a conventional composite resin (6 mm diameter and 2 mm thick) and 40 specimens of the bulk-fill Tetric EvoCeram composite resin at two different thicknesses (6 mm diameter and 2 mm thick or 4 mm thick, n = 20) were prepared. The specimens were stored in distilled water during the study period (28 d). Half of the specimens were remained in distilled water and the other half were immersed in coffee solution 20 min/d and kept in distilled water between the cycles. Color changes (ΔE) were measured using the CIE L ⁎ a ⁎ b ⁎ color space and a digital imaging system at 1, 7, 14, and 28 days of storage. Data were analyzed using Two-way ANOVA and Tukey's HSD post hoc test (P < 0.05). Composite resins showed significant increase in color changes by time (bulk-fill > conventional; P < 0.001). Coffee exhibited significantly more staining susceptibility than that of distilled water (P < 0.001). There was greater color changes with increasing the increment thickness, which was significant at 14 (P < 0.001) and 28 d (P < 0.01). Color change of bulk-fill composite resin was greater than that of the conventional one after coffee staining and is also a function of increment thicknesses.

Background: Since the introduction of resin composites, the staining of resin-based materials by colored solutions such as coffee, tea, chlorhexidine (CHX), and other beverages has become a common concern. Aim: The aim of this study was to evaluate the effect of home and office bleaching as a treatment for discoloration of composite after immersion in coffee or CHX. Materials and Methods: A microhybrid composite (Z250), nanohybrid composite (Z550), and nanofill composite (ultimate, body shade) were selected. Forty disk shape specimens (8 mm diameter and 2 mm thickness) for each composite were prepared then divided into two groups according to staining solutions (25 g of coffee in 250 ml water, 20 min/day or 0.2% CHX, 1 min/day). Following 1 month staining, specimens were divided into two groups again. Half of the specimens was bleached with in office bleaching agent (Opalescence Boost 40% hydrogen peroxide concentration) 3 times in one visit for 15minutes and the others subjected to home bleaching agent(Opalescence 10% carbamide peroxide) 6h/day until 2 weeks both from Ultradent Products, Inc., South Jordan, UT, USA. Color of the specimens was measured with a spectrophotometer using CIELAB color space at baseline, after 1 month staining, and after ending the bleaching process. Statistical Analysis: Analysis of variance was used to analyze the data ( P < 0.05). Results: Coffee and CHX provided significant color changes in all groups ( P < 0.05). Z550 was the material more prone to discoloration in coffee in comparison with Filtek Ultimate ( P = 0.003). After bleaching, materials showed significant reduction except stained Z550 by coffee in home bleaching groups. Both home and office bleaching provided significant color changes in all CHX groups ( P < 0.05). Conclusion: Coffee produced more color changes than CHX. The hydrogen peroxide has the same whitening effect in comparison with carbamide peroxide.

Objectives: This study aimed to evaluate the ability of lithium disilicate ceramics to reproduce the A2 shade and to mask A4 substrates. Materials and Methods: Twenty-four discs (8 mm in diameter, shade A2) of high translucency (groups 1-3) and low translucency (groups 4-6) of IPS e.max ceramic with different thicknesses (0.5, 0.75, and 1 mm) were fabricated as monolithic structures. In addition, discs of medium opacity (group 7-8) with different core/veneer combinations (0.3 mm/0.7 mm and 0.5 mm/0.5 mm) were fabricated as bilayer structures. Specimens were superimposed on an A4 substrate (complex). The color changes of the complex were measured using a spectrophotometer on a black background, and the ΔE values of the complex were compared with either the A4 substrate or the A2 shade tab. One-way analysis of variance, the Tukey honest significant difference test, and the Fisher test were used to analyze the data (p < 0.05). Results: Significant between-group differences were found for comparisons to both the A4 substrate and the A2 shade (p < 0.05). When compared with the A4 substrate, the ΔE values in all groups were in the non-acceptable range. When compared with the A2 shade, the ΔE values in all groups, except groups 2 and 3, were in the clinically acceptable range. Conclusions: All translucencies and thicknesses masked the underlying dark substrate. However, the low-translucency IPS e.max Press better reproduced the A2 shade.

Background: Mechanical oral hygiene procedures are the most effective means of plaque removal and toothbrush is the most commonly used tool for mechanical plaque removal worldwide. There is an array of available manual and electric toothbrushes in the market. Thus, choosing the best one for dental plaque removal can be of great help for patients. Objectives: This study aimed at compare the efficacy of dental plaque removal using a manual and an electric toothbrush. Materials and Methods:This experimental, single-blinded sequential clinical trial was conducted on 12 patients (ten females and two males) who aged 21 to 30 years old. The tested manual toothbrush was 35-mm soft Oral-B Pulsar and the electric one was Oral-B Professional Care 8500 DLX chargeable D18. Patients' dental plaque score was set as zero through scaling, root planning, and polishing. Subjects were avoided tooth cleaning for three days and on day four, plaque accumulation was assessed using Tureskey's modification of Quigley and Hein plaque index. Results: The mean of plaque index was 2.13 ± 0.83 and 2.11 ± 1.01 in the manual and electric toothbrush groups, respectively. No significant difference was detected between the study toothbrushes in terms of plaque removal (P = 0.374); however, with the manual tooth brushing, plaque removal was significantly greater in the buccal than in lingual surface and in the maxilla than in the mandible (P = 0.03 and P = 0.015, respectively). Conclusions: Similar to previous studies, this study could not show the superiority of electric toothbrush over manual in plaque removal. After 72 hours, the mean of plaque index was greater in buccal than in lingual surface, which may be attributed to the natural cleansing action of the tongue.

Objectives. This in vitro study was aimed to assess the effect of wet and dry finishing and polishing techniques on the flexural strength and microhardness of different commercial nanoparticle contained composite resins. Methods and Materials. The samples were made of Z250 (microhybrid), Z350 XT (nanofilled), and Z550 (nanohybrid) resin composites. Each group was subdivided into 2 subgroups according to polishing protocols. Subgroup 1 for each composite underwent wet polishing, and subgroup 2 was subject to dry polishing technique. Flexural strength and microhardness of the samples were measured at two different times of polishing (T0 and T24). The flexural strength test and microhardness test were measured by a 3-point bending test using a universal testing machine, and a Vickers machine, respectively. Data were analyzed by Kolmogorov–Smirnov, two-way ANOVA, and Tukey HSD tests. Results. ANOVA showed that the type of composite has a significant effect on flexural strength. Two-way ANOVA showed that, at T0, flexural strength of all composites in the dry technique was higher than in the wet technique ( p = 0.019 ). At T24, Z350 XT had the lowest, and Z250 had the highest flexural strength in both techniques. The time and technique of polishing were also significantly effective on hardness. At T0, hardness was higher in the wet compared to the dry method ( p = 0.008 ). Tukey test showed that, at T24, the hardness of Z350 XT was significantly higher than the other materials in both techniques. Conclusion. Immediate wet finishing and polishing presented lower flexural strength. Delayed dry/wet finishing and polishing significantly enhanced the hardness of the samples.