Experimental chitosan-based hydrogel for in-office bleaching: efficacy and effects on early- stage eroded/abraded enamel

• Grant number: 25/14877-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2025
• End date: October 31, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Vanessa Cavalli Gobbo
• Grantee: Ester Nathália da Fonseca Pereira
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

New bleaching gel formulations have been proposed to minimize the deleterious effects on dental enamel while maintaining bleaching efficacy. This study is derived from the candidate's doctoral project Marcos Roberto de Lima Benati (FAPESP - Process 2025/12411-2, under analysis), which aims to develop and characterize a bleaching hydrogel chitosan-based, containing nanohydroxyapatite and pH 35% and evaluate its bleaching efficacy (in vitro and in vivo) and biocompatibility in healthy enamel. The difference in this research will be the application of bleaching hydrogels to enamel subjected to erosive/abrasive challenge, searching to evaluate, mainly, the remineralizing potential of the chitosan hydrogel, with specific analyses for this purpose. In general, the objective of this study will be to evaluate the efficacy, mineral content and morphology of an experimental bleaching agent using chitosan hydrogel in comparison to carbomer hydrogel associated with hydrogen peroxide (HP) at a concentration of 35%, for in-office bleaching. Enamel/dentin blocks of bovine incisors will be obtained and half of these blocks will be subjected to erosive/abrasive challenge and will be immersed in 1% citric acid (5 min) and artificial saliva (120 min) three times to produce enamel at the initial stage. Simulated brushing will be performed only after the first immersion in saliva, to promote enamel abrasion. The healthy blocks and those with initial erosion lesions will be selected and subjected to treatments with (n=15): HP35% (commercial control), chitosan hydrogel + HP35% and carbomer hydrogel + HP35%, in healthy enamel, and HP35% (commercial control), chitosan hydrogel + HP35% and carbomer hydrogel + HP35%, in enamel with initial erosion/abrasion lesions. Bleaching will be performed in 3 sessions of 30 min with a 7-day interval. The following will be evaluated: color [parameters L*, a*, b*, bleaching index (¿WID) and color change (¿E00) in spectrophotometry], mineral content [surface microhardness (KHN)], analysis of surface loss (SL) in profilometry and surface morphology, in scanning electron microscopy (SEM). The results will be statistically analyzed adopting a significance level of 5%. (AU)