The use of fluoride for maintenance / restoration of oral health has been widely investigated in human (brachydont) teeth, especially for prevention of caries. The benefits of fluoride include: its ability to alter the demineralisation / remineralisation balance towards remineralisation by formation of fluoroapatite crystals and calcium fluoride, and its antibacterial effect. Fluoride has the advantage of becoming incorporated into (human) enamel and is also present in dental plaque and saliva. To date there are no published reports of the efficacy of fluoride in preventing / treating equine dental caries. The efficacy of fluoride may differ in continuously erupting hypsodont equine teeth, which in contrast to enamel covered clinical crowns of brachydont teeth, have cementum, dentine and enamel exposed. An ex-vivo study was conducted to evaluate the penetration depth and distribution of fluoride (as fluorine) in dental tissues using Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and Secondary Ion Mass Spectrometry. Several sites (with and without peripheral caries) treated with fluoride varnish were compared to control sites.