Bioactive toothpastes in dentin hypersensitivity treatment: A systematic review

Dentin hypersensitivity (DH) is characterized by short or transient sharp pain arising from exposed dentin in response to thermal, physical, osmotic, or chemical elements (Holland et al., 1997, West et al., 2011). According to the hydrodynamic theory, hypersensitivity results from the rapid movement of the fluid within the dentinal tubules (Brannstrom et al., 1968). It is imperative to the efficacy of the DH treatment to address the etiological factors of the condition (Femiano et al., 2017). Desensitizing therapies consist of the use of chemical substances, laser irradiation, restorative treatments, periodontal surgeries which aim basically to control the hydrodynamic mechanisms of pain. However, these treatments do not achieve predictable results in all patients and may lose their effect over time (Cartwright, 2014, Zhu et al., 2015, Sole-Magdalena et al., 2017). Bioactive glass materials have been proposed for the treatment of DH (David, 2010, Curtis et al., 2010, Barry et al., 2011, Sauro et al., 2011, Cartwright, 2014, Hall et al., 2017, Bansal and Mahajan, 2017). The mechanism of action of bioactive glass starts when the material is exposed to an aqueous environment. The sodium ions (Na+) in the particles immediately are switched with hydrogen cations (H+ or H3O+). This rapid release of ions allows the calcium ions (Ca+2) in the particle structure, as well as the phosphate ions (PO4-3), to be released from the glass particles. The initial reactions occur in seconds of exposure and the release of the Ca+2 and PO4-3 ions continues as long as the particles are exposed to an aqueous environment. A localized and transient increase in pH occurs during the initial material exposure due to the release of Na+. This increase in pH helps to precipitate the Ca+2 and PO4-3 ions of the particle to form a layer of calcium phosphate Ca(PO4)2. As particle reactions and the deposition of calcium and phosphorus complexes are maintened, the layer crystallizes into hydroxycarbonate apatite which is chemically and structurally equal to biological apatite. The combination of residual particles and the newly formed apatite layer lead to physically occluding the dentin tubules, resulting in remission or pain reduction (Zhong et al., 2002, Zanotto et al., 2004, Hench, 2006). The maintenance of this layer on the dentin surface is a major challenge for the materials existing in the market, besides knowing the effectiveness of them for the treatment of DH. Studies have shown the absence of parameters such as: patient follow-up time, control groups, assessment scale for degree of pain, DH diagnostic methods and form of application of the product (Matranga et al., 2017, Hannigan and Lynch, 2013, Kim et al., 2011, Pandis et al., 2011, Fleming et al., 2013). The use of bioactive materials is a promising proposal for DH due to the the neoformation of a bioactive barrier on dentin surface (Bansal and Mahajan, 2017). They showed the ability to occlude the dentinal tubules and form a mechanically strong layer of hydroxyapatite on the dentin surface, which can resist degradation by repeated acid challenges (Du et al., 2008). Thus, the aim of this systematic review was to assess randomized controlled trials (RCT) carried out in the permanent teeth of adult patients in the DH treatment with bioactive dentrifices, either at-home or in-office.