Effect of coffe and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching

There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. Objective: To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Materials and methods: Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max) and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO) before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD) at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E) and lightness (∆L) variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05). Results: Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001). All specimens presented a decrease in brightness (negative ∆L). The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively). Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. Conclusion: The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching

Hybrid Layer Width after Conventional Diamond, Carbide and Ultra-Sound CVD Burs

Objectives: The aim of the present study was to evaluate hybrid layer thickness of primary molars sectioned with diamond, carbide and ultrasonic CVD burs. Study Design: The occlusal enamel surfaces of ten molars were removed and superficial dentin was exposed. Three standardized cavities were prepared at mesial, central and distal exposed dentin with diamond, carbide and ultrasonic CVD burs, respectively. A self-etching adhesive system (Adhese, Ivoclar/Vivadent) was applied to prepared cavities and composite resin Z100 (3M/ESPE) was inserted according to manufacturers’ instructions to hybridized dentin. Samples were lightcured and the crown was sectioned mesio-distally dividing the restored cavities in two halves which were observed under scanning electron microscopy (SEM), in order to quantitatively evaluate hybrid layer thickness (µm). Three repeated measures were performed at mesial, central and distal sites and mean values obtained were submitted to one-way analysis of variance (ANOVA). Results: Data (mean ± sd) obtained were (µm): 2.69 (0.44), 3.38 (1.23) and 2.72 (1.18) for diamond, carbide and CVD burs, respectively. No differences were observed among groups (p ≯ 0.05). The adhesive systems promoted mechanical retention, uniform and continuous hybrid layer and resin tags formation at all dentin sites for all instruments tested. Conclusion: The results suggest that the minimally invasive cavities prepared with diamond, carbide and CVD for ultrasound, promoted hybrid layer formation with a similar thickness regardless the bur used.</jats:p

Microleakage at the composite-repair interface: Effect of different surface treatment methods

This study evaluated microleakage at the composite-repair interface after using different methods of surface treatment. Eighty resin composite specimens (Filtek Z250, 3M Dental Products) aged in artificial saliva for three months were divided into four groups (n=20) according to the following surface treatment methods: untreated control-no roughening or abrasion of the surface; roughening with diamond burs; jet prophylaxis with sodium bicarbonate particles and air abrasion with 50 lam aluminum oxide particles. Each method was examined using scanning electron microscopy (SEM) to evaluate changes in surface topography. All groups were then etched with 37% phosphoric acid, coated with a bonding agent (Single Bond, 3M Dental Products) and received new resin applications. The samples were then thermocycled (800 cycles/5degreesC to 55degreesC [+/-2]) and immersed in 2% methylene blue buffered dye solution (7.0 pH) for four hours. Three examiners measured the extent of microleakage in a stereoscope microscope using four representative scores. For all experimental groups, no significant difference in repair microleakage was identified by the Kruskal-Wallis test (p>0.05). Therefore, different testing methods of surface treatment showed the same effect on dye penetration along the repair interface.30111311