In vivo and in vitro evaluation of Biosilicate® against oxidative stress, hydrogen peroxide penetration and bleaching efficacy.

Author(s)

Marina Carminatti

• Document type: Master's Dissertation
• Press: Araçatuba. 2019-07-22.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2019-06-14
• Advisor: Luciano Tavares Angelo Cintra; André Luiz Fraga Briso

Abstract

New products are being developed with the purpose of mitigating the effects of the compounds used in bleaching procedures. The objective of the present study was to evaluate in vivo the therapeutic potential of Biosilicate® (BS) gel on the pulp tissue of Wistar rats by means of histological and immunohistochemical analysis, as well as to analyze in vitro, the penetration of H2O2 and bleaching efficiency in bovine teeth. For this, this study was divided into 2 parts. Part 1: In vivo segment: 50 hemi-maxilla of 25 rats were randomly divided into 5 groups (n = 10): Control- received no treatment; CLA- received 30 min of the 35% H2O2 bleaching gel; BS-CLA- received 20 min of BS gel, followed by 30 min of 35% H2O2; CLA+BS- received 30 min of a mixture of 35% H2O2 with the BS gel (1:1); CLA+H2O- received 30 min of a mixture of 35% H2O2 with distilled water (1:1). After 2 days, the animals were killed and the hemi-maxils separated for histological analysis in H.E. Inflammation scores and data submitted to the Kruskal-Wallis and Dunn tests and Mann-Whitney test (p<0.05) were assigned. Segment in vitro: 50 discs of bovine teeth were coupled in artificial pulp chambers, and divided into 5 groups (n=10) that received the same treatments as the in vivo segment. The penetration of H2O2 by enamel and dentin was quantified based on the reaction of this with the leucocrystal violet dye. The color change was analyzed by the CIELab system, in the periods: before the bleaching session - (T0), immediately after (T1), and 24 hours after (T2), and data submitted to analysis of variance (ANOVA) followed by the test Tukey (p<0.05). Part 2: 40 hemi-maxillae of 20 rats were randomly divided into 4 groups (n=10): Control- received no treatment; CLA- received 30 min of the 35% H2O2 bleaching gel; BS-CLA- received 20 min of BS gel, followed by 30 min of 35% H2O2; CLA+BS- received 30 min of a mixture of 35% H2O2 with the BS gel (1:1). After 2 days, the animals were killed and the hemi-maxilla separated for histological analysis in HE and immunohistochemistry for PCNA, HO-1, TNF-α and P-Substance. Scores were assigned to TNF-α inflammation and immunostaining, and submitted to the Kruskal-Wallis and Dunn tests (p<0.05). For the analysis of the area corresponding to the immunostaining obtained through the optical density of the Substance P, an analysis of the variance (ANOVA) was performed, followed by the Tukey test for comparison between the means. We counted the immunolabellated cells for HO-1 and PCNA and were submitted to the Shapiro-Wilk normality test to define the statistical test (p<0.05). In the histological analysis, the CLA group presented predominantly necrosis in the occlusal and middle third of the coronary pulp, whereas the BS-CLA presented severe inflammation in the occlusal third and moderate in the middle third, both different from the Control (p<0.05). The CLA+BS group presented moderate inflammation in the occlusal third, with no difference for the BS-CLA group (p> 0.05), slight inflammation in the middle third, and absence of inflammation in the cervical third without difference for Control (p>0,05). The CLA+H2O group had mild inflammation in the occlusal third and absent in the remaining thirds, with no difference for CLA+BS and Control group (p>0.05). In the cervical third, the CLA group had moderate inflammation, different from the Control group (p<0.05). The CLA and BS-CLA groups presented higher penetration of H2O2 (p<0.05). At the immediate color change and after 24 hours, the CLA, BS-CLA and CLA+BS groups presented similar color changes (p>0.05).Conclusion: Given the results obtained in both studies, it can be concluded that Biosilicate® is able to reduce the inflammatory process caused by the bleaching gel and helps in the repair process. The application protocol of BS blended with the bleaching gel showed better results as it reduces the penetration of the bleaching gel and maintains bleaching efficacy. (AU)

• FAPESP's process: 16/23362-3 - Therapeutic potential evaluation of biosilicate gel against the oxidative stress of the pulp tissue due to dental bleaching and its influence on the penetration capacity of hydrogen peroxide and bleaching efficiency. in vivo and in vitro study
• Grantee: Marina Carminatti
• Support Opportunities: Scholarships in Brazil - Master