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stannous chloride

Also known as: Stannous chloride, Tin(II) chloride, SnCl₂

Overview

Stannous chloride, also known as tin(II) chloride, is an inorganic tin compound with the chemical formula SnCl₂. It is primarily synthesized industrially and is not naturally occurring in significant amounts. It is widely used as a food additive (E 512) for preservation and coloring, and in oral care products, such as toothpaste and mouth rinses, for its antimicrobial and anti-caries properties. Stannous chloride exhibits antimicrobial activity, inhibits bacterial adhesion, and has anti-inflammatory effects in the oral cavity. Research on stannous chloride is considered moderately mature, with extensive studies in oral health contexts and some toxicological evaluations. The available evidence includes regulatory re-evaluations, toxicological studies, and clinical trials primarily related to oral health applications.

Benefits

Stannous chloride offers several evidence-based benefits, primarily in oral health. It exhibits antimicrobial activity against oral bacteria, reducing plaque formation and caries risk by inhibiting bacterial metabolism and adhesion. Clinical studies show significant reductions in plaque and gingivitis scores with stannous fluoride/chloride dentifrices compared to controls. Stannous chloride also has anti-hypersensitivity effects in dentifrices, with substantivity lasting up to 12 hours. Additionally, it provides anti-inflammatory effects by preventing bacterial-induced inflammatory responses in the oral mucosa. These benefits are particularly effective in populations with gingivitis and mild gum disease when used in toothpaste formulations. Benefits are typically observed with daily use over at least 2 weeks, with antimicrobial effects persisting up to 12 hours post-application.

How it works

Stannous chloride primarily works by interfering with bacterial metabolic functions. Stannous ions restrict sugar uptake and inhibit enzymes critical for bacterial survival. It acts locally in the oral cavity, binding to bacterial cells and oral tissues, reducing bacterial adhesion and inflammatory signaling. While the exact molecular targets are not fully elucidated, it is known to disrupt bacterial metabolism. Absorption and bioavailability are minimal when used topically in oral care, with systemic exposure primarily from ingestion or occupational exposure.

Side effects

Stannous chloride is generally recognized as safe when used in approved concentrations in food and oral care products. Common side effects include possible mild oral irritation or staining of teeth with prolonged use of stannous-containing dentifrices. Uncommon side effects may include taste alteration or mild gastrointestinal discomfort if ingested in larger amounts. Rare side effects include the potential for allergic reactions in sensitive individuals. There are no well-documented systemic drug interactions due to low systemic absorption. It should be avoided in individuals with known hypersensitivity to tin compounds. Toxicological data from animal studies indicate high doses may cause adverse effects; however, typical human exposures are much lower and considered safe.

Dosage

For oral care, toothpastes containing approximately 0.4% stannous fluoride or equivalent stannous chloride concentration used once daily have demonstrated efficacy. Stabilized formulations with 0.4% stannous fluoride or equivalent stannous chloride concentrations are generally recommended. There is no established maximum dose for oral care use, but toxicological studies indicate acute oral toxicity at doses exceeding hundreds of mg/kg in animals. Daily use is recommended, with antimicrobial effects lasting up to 12 hours post-application. Stabilized dentifrice formulations are preferred to maintain efficacy and minimize side effects such as staining. Topical application limits systemic absorption, and ingestion should be minimized. Stabilizing agents such as zinc phosphate and glycerin improve formulation stability and bioavailability.

FAQs

Is stannous chloride safe for daily use in toothpaste?

Yes, when used in stabilized formulations at approved concentrations, it is safe and effective for daily oral care. Regulatory bodies have deemed it safe at typical exposure levels.

Can stannous chloride cause tooth staining?

Yes, staining is a known side effect but can be minimized with stabilized formulations and proper oral hygiene practices. Newer formulations are designed to reduce staining.

How quickly does stannous chloride work?

Antimicrobial and anti-hypersensitivity effects can be observed within 2 weeks of daily use. Consistent use is key to maintaining these benefits.

Is there a risk of systemic toxicity?

Systemic toxicity is unlikely at doses used in oral care. High-dose animal studies show toxicity only at much higher exposures than typical human use.

Research Sources

https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2018.5295 – The EFSA panel's 2018 re-evaluation concluded that stannous chloride is safe as a food additive at current use levels. The panel found no significant toxicological concerns at typical exposure levels, emphasizing the importance of dose in safety assessment.
https://dimensionsofdentalhygiene.com/article/new-generation-stannous-fluoride/ – A 2021 review highlighted the broad-spectrum antimicrobial effects, anti-caries benefits, and anti-hypersensitivity properties of stannous fluoride dentifrices. The review emphasized that stabilized formulations maintain efficacy and reduce side effects such as staining.
https://ntp.niehs.nih.gov/sites/default/files/ntp/htdocs/lt_rpts/tr231.pdf – Animal carcinogenicity studies by the National Toxicology Program showed some increased tumor incidences at high doses, but overall conclusions were mixed. The study suggested caution at high exposure levels, despite being well-conducted.
https://www.atsdr.cdc.gov/toxprofiles/tp55-c3.pdf – The ATSDR toxicological profile detailed toxic effects of tin compounds, including stannous chloride, noting acute toxicity at high doses in animals. The profile indicated generally low toxicity at typical human exposure levels.
https://www.webmd.com/vitamins/ai/ingredientmono-1520/tin – WebMD provides general information about tin, including its uses and potential side effects. It is important to note that WebMD is a general information source and may not always reflect the most up-to-date scientific consensus.