Stannous Fluoride in Toothpastes: A Review of Its Clinical Effects and Likely Mechanisms of Action.

Abstract

This article reviews the topic of stannous fluoride as an anti-caries additive in toothpastes. It is based on a literature survey carried out using Science Direct, supplemented by information from PubMed. The keywords used were stannous fluoride, toothpaste, clinical effects, caries, hypersensitivity, gingival health, structure and aqueous solutions. The initial searches covered the period 2015-2024 and identified 57 references. Older references cited in these papers, and also papers already known to the author, were also included. The information thus obtained shows that stannous fluoride has three main effects, namely, reduction in the viability of the oral biofilm, increase in remineralisation of the hydroxyapatite tooth mineral and occlusion of dentinal tubules leading to reduced hypersensitivity. Stannous fluoride was shown to be the most effective of all the fluoride additives used in toothpastes. In much of the dental literature, this is attributed to the effects of Sn²⁺ ions. However, as has been shown extensively in the wider scientific literature, free Sn²⁺ ions do not occur in aqueous systems. Rather, the initial products of the dissolution of SnF₂ is undissociated, hydrated SnF₂ and SnF⁺ ions. These gradually exchange fluoride to form Sn(OH)₂ and Sn(OH)⁺. Their likely mechanism of action based on their toxicity towards oral micro-organisms and their interaction with hydroxyapatite is discussed.