This study investigated the effects of laser irradiation associated with photo-absorbing agents containing sodium fluoride (NaF), MI paste Plus or Remin Pro® on microhardness and surface structure of white spot lesions (WSLs). Fifty-six premolars were divided into two halves, then immersed in a demineraling solution to induce WSLs. The samples were divided into 8 groups by treatment (n=12) : (1) control, (2) diode laser (810 nm, 500 mW, 90 s), (3) NaF, (4) MI Paste plus, (5) Remin Pro®, (6) NaF + Laser, (7) MI Paste Plus + Laser, (8) Remin Pro® + Laser. Microhardness was measured before and after remineralization treatments. Two samples from each group were selected for SEM analysis. Microhardness increased significantly after all treatments with the exception of control, Laser and Remin Pro® groups (p >0.05). ANOVA revealed no significant difference in initial microhardness (P=0.21), whereas a significant difference was noted after treatment (P=0.009). The application of sodium fluoride with or without laser irradiation produced the highest microhardness among the groups (p<0.05). SEM analysis revealed some cracks on lased enamel and non-homogenous coatings of minerals after the use of remineralizing products. The use of NaF either alone or combined with laser irradiation was the most effecttive strategy for increasing microhardness of WSLs. The application of diode laser through photoabsorbing agents containing sodium fluoride or MI Paste Plus did not produce any additional effects in enhancing remineralization of WSLs, whereas the combined application of diode laser with Remin Pro® was effective. Key words:CPP-ACP, Enamel caries, fluoride, Hydroxyapatite, Low level laser, Microhardness, Remineralization, casein phosphopeptide amorphous calcium phosphate.

Background and Objectives. Charcoal-containing toothpastes have become popular among many patients; however, there is inadequate scientific evidence on oral health. This study aimed to evaluate the color change, surface microhardness, and roughness of bovine enamel and composite resin submitted to simulated toothbrushing with a whitening toothpaste containing activated charcoal. Methods. Thirty-six bovine incisors and resin composite samples were prepared, stained with black tea, and then randomly divided into two groups. The samples were brushed with a charcoal-containing toothpaste (Colgate® MAX WHITE) and daily toothpaste (Colgate® Max Fresh) for 10,000 cycles. Before and after brushing cycles, color variables (ΔL, Δa, Δb), total color change (ΔE), plus Vickers microhardness were evaluated. Two samples of each group were prepared for surface roughness assessment via atomic force microscope. Data were analyzed by Shapiro–Wilk, Independent sample t-test and Mann–Whitney U tests. Results. According to the obtained results, ΔE and ΔL were significantly higher whereas Δa and Δb were noticeably lower in charcoal-containing toothpaste group in comparison with daily toothpaste in both composite and enamel samples. The microhardness of samples brushed with Colgate® MAX WHITE was significantly higher than that of Colgate® Max Fresh in enamel ( ), whereas no significant difference was found in composite resin samples ( ). Colgate® MAX WHITE enhanced the roughness of both enamel and composite surfaces. Conclusion. The charcoal-containing toothpaste could improve the color of both enamel and resin composite with no negative effect on microhardness. Nevertheless, its adverse roughening effect should be considered occasionally on composite restorations.

Achieving a seamless color match in resin composite restorations remains a significant clinical challenge due to variations in tooth structure and background shades. The aim of this in vitro study was to assess the effect of background shade, thermal aging, and composite thickness on color matching and translucency of three single-shade resin composites. A total of 72 resin composite disks (12 mm diameter) were fabricated using three single‐shade composites -Omnichroma (OMN), Charisma Diamond ONE (CDO), and Charisma Topaz ONE (CTO)- in two thicknesses (1.5 and 3 mm), resulting in six groups (n = 12 per group). Subsequently, three background disks were prepared from Estelite Sigma Quick in shades A1, A3, and B1, and the 72 composite disks were positioned on these background disks to form a two‐layer assembly for evaluation. The L*, a*, and b* variables before and after thermocycling (10,000 cycles) were recorded and blending effect (BE) was calculated. The translucency was evaluated by using white and black backgrounds. The data were analyzed by Kolmogorov–Smirnov, ANOVA, Independent Samples T-test, and Tukey HSD tests with the significance level set at 5%. OMN exhibited a significantly superior BE compared to CTO and CDO, both before and after aging (p < 0.001). Color matching was significantly better at 1.5 mm than at 3 mm, except for CTO and CDO on the A3 background (p = 0.193 and p = 0.550, respectively). BE was highest on the A1 background, intermediate on B1, and lowest on A3 (p < 0.001). Translucency was significantly higher at 1.5 mm than at 3 mm (p < 0.001), except for CTO on A3 after aging (p = 0.198), while background shade did not affect translucency (p > 0.05). The BE of single-shade resin composite is material and thickness-dependent. Overall, OMN demonstrated superior shade matching across different backgrounds compared to CDO and CTO, at both thicknesses, before and after aging. Understanding the influence of composite material, thickness, and underlying shade can optimize color matching in dental restorations, improving clinical outcomes and esthetics.

Background: This study investigated the impact of different surface treatments, including fractional carbon dioxide (CO₂) laser on shear bond strength (SBS) of resin cement to lithium disilicate ceramic. Materials and Methods: In this in vitro study, 72 blocks of IPS e.max CAD ceramic were randomly divided into six groups in terms of treatment (n = 12). Group 1 underwent etching with 9.6% hydrofluoric (HF) acid, whereas group 2 was subjected to air abrasion with aluminum oxide particles. Groups 3 and 4 were treated with a fractional CO₂laser for 10 s using 10 W/14 mJ (group 3) or 20 W/10 mJ (group 4). In groups 5 and 6, the CO₂laser was applied similar to that in groups 3 and 4, respectively; then, the specimens were etched by HF acid. After silane application, luting cement was bonded to the specimens. The SBS was assessed with a universal testing machine, and the type of bond failure was determined. Data were analyzed by ANOVA, Duncan, and Fisher's exact tests. Results: Surface conditioning with fractional CO₂laser alone resulted in significantly lower SBS than HF acid treatment (P < 0.05). Bond strengths of the specimens treated with a combination of laser irradiation and acid etching were significantly greater than all the other groups (P < 0.05). No significant difference was found in the distribution of failure modes among the groups (P = 0.337). Conclusion: The combination of fractional CO₂laser irradiation and HF acid etching could be recommended when extra retention is required for lithium disilicate-based restorations, whereas laser treatment alone cannot produce sufficient SBS.

Objective: The aim of this study was to evaluate reinforcing effect of different fiber‐reinforced resin composites for restoring structurally compromised molars compared to conventional resin composite. Methods and Materials: Sixty healthy human third molars were randomly divided into six groups ( n = 10). In G1 to G4, wide mesio–occluso–distal (MOD) cavities with an occlusal depth of 4 mm and proximal boxes with a width of 2/3 of buccolingual distance were prepared. In G5, after preparation of MOD cavities, 2 mm cusp reduction was made. The samples of G6 were remained intact (control). In G1 and G5, the conventional resin composite (G‐ænial Posterior), and in G2, short fiber‐reinforced resin composite (SFRC: EverX Posterior) were used. In G3 and G4, the Ribbond fibers were applied on base of cavity in buccolingual and cross‐sectional direction, respectively, and followed by conventional resin composite restoration. After 24 h maintaining in distilled water at room temperature, fracture resistance of restored teeth was tested with a crosshead speed of 0.5 mm/s and fracture patterns were also evaluated by stereomicroscope (favorable: above cementoenamel junction (CEJ) and unfavorable: below CEJ). The data was analyzed using Shapiro–Wilk, one‐way ANOVA, and post hoc Tukey’s HSD tests. Results: The highest fracture strength was obtained in G2 (4051.4 ± 1293.9 N), which was significantly greater than G3 (2886.6 ± 720.4 N; p = 0.005) and G5 (2949.3 ± 307.5 N; p = 0.010). No statistically significant difference was observed between other study groups. The greatest percentage of favorable fracture was recorded in G6 (70%) and G2 (60%). Conclusion: The reconstruction of severely weakened molar teeth with SFRC or incorporating of polyethylene fibers in cross‐sectional direction on base of resin composite restoration improved fracture strength and favorably affected fracture modes in comparison to conventional posterior resin composite with or without cusp coverage.

Periodontal diseases are highly prevalent and can affect high percentage of the worlds’ population. Oxidative stress and inflammation play an important role in the pathogenesis of periodontal diseases. Nowadays, more attention has been focused on the herbal remedies in the field of drug discovery. Green tea is an important source of polyphenol antioxidants. It has long been used as a beverage worldwide. The most interesting polyphenol components of green tea leaves that are related with health benefits are the catechins. Taken together, this review suggested that green tea, with its wide spectrum of activities, could be a healthy alternative for controlling the damaging reactions seen in periodontal diseases.