Aim Assessing the intracoronal bleaching effectiveness of an experimental chlorine dioxide product, based on the walking bleach technique. Methods Extracted bovine incisors were artificially stained with bovine blood and filled with zinc phosphate cement at cementoenamel junction level. Teeth were divided into 3 groups (n=10): (SP) sodium perborate added with distilled water, (CD) chlorine dioxide and (C) control – dry cotton inserted into the pulp chamber. Bleaching agents were used at 0, 7 and 14 days. VITA Easyshadetm (∆Eab) was used to analyze tooth color at the 7th, 14th and 21st days, based on the CIE2000 system. Data were analyzed through ANOVA and Tukey’s test. Results There were no statistically significant differences in Δb, ΔE, ΔE00 and ΔWID between CD and the control group. These parameters have shown significant differences between CD and SP, which differed from the control. However, they did not show significant differences either in the control group or in CD at the 7th, 14th and 21st days. Values recorded for SP at the 7th day differed from those recorded at the 14th and 21st days. Δa has shown differences within the same group at the 7th, 14th and 21st days. There was no difference between groups, when they were compared at the same day (7th and 14th). The control group differed from SP at the 21st day. CD did not differ from the other two groups. ΔL did not show differences between groups and times. Conclusion Stabilized chlorine dioxide (0.07%, at pH 3.5) should not be used as intracoronal bleaching agent along with the walking bleach technique.

Abstract Aim: To evaluate if gypsum mixed with different water types, with their different compositions influence the dimensional change, surface roughness and compressive strength of type IV and V gypsum specimens. Methods: Sixty specimens were fabricated from metal matrices and divided into six groups (n=10) according to the used type of gypsum and water: G1, G2 and G3 - type IV gypsum and tap, mineral and distilled water, respectively; G4, G5 and G6 - type V gypsum and tap, mineral and distilled water, respectively. Water/powder ratio followed the manufacturer's recommendations (19 mL/100 g) in all groups. The same specimens were used for all tests. A micrometer dial evaluated the dimensional change. The surface roughness of three random points was determined with a rugosimeter; a universal testing machine performed the compressive strength test. The data were subjected to analysis of variance (ANOVA). Results: There was no statistically significant difference (p>0.05) between the three types of water in the studied variables. There was statistically significant difference (p<0.05) between the gypsum mixes for the dimensional change variable. Conclusions: The different water types, with their different compositions, did not influence the analyzed physical and mechanical properties.