Influence of calcium lactate and sodium fluoride solution mouthwashes on enamel microhardness and dentin permeability during in-office bleaching

Abstract

Objective: This study evaluated the influence of calcium lactate and sodium fluoride mouthwashes on enamelmicrohardness and dentin permeability during in-office bleaching. Material and Methods: For the microhardnessevaluation, enamel blocks were randomly submitted to different treatments associated with in-office bleachingagent using 40% hydrogen peroxide (Opalescence Boost PF 40%/ Ultradent; 3 sessions x 40-minute each)(n = 10): 1) Control: application of bleaching agent; 2) Calcium lactate: 1-minute immersion before bleachingtreatment; 3) Sodium fluoride: immersion for 1 minute before bleaching treatment; 4) Calcium lactate +sodium fluoride: 1 minute immersion in calcium lactate solution, followed by 1 minute immersion in sodiumfluoride before bleaching treatment. Dentin discs received the same treatment protocols (n = 10) to evaluatepermeability. Knoop microhardness and dentin permeability assessments were performed twice (at baseline and48 hours after the end of bleaching treatment). Results: The generalized linear model considering the design ofrepeated measures over time showed that there was no significant difference between treatments (p = 0.9577)and between assessments (p = 0.3267) regarding Knoop microhardness. Kruskal Wallis and Dunn tests showedthat calcium lactate immersion before bleaching treatment provided higher dentin permeability than othergroups (p = 0.0009). Conclusion: The use of sodium fluoride solution and calcium lactate in association within-office bleaching treatment did not influence the microhardness of tooth enamel, although calcium lactatemay increase dentin permeability.KEYWORDSTooth bleaching; Dentin; Sodium fluoride; Calcium lactate; Hardness tests.