The Effect of Formalin Fixation Upon Fluoride Uptake in Enamel and Dentin of Extracted Human Teeth

Abstract

The fluoride uptake in enamel and dentin surfaces, as evidenced by the reduction in [F−] in fluoride containing solutions, was studied in formalin fixed and unfixed specimens. Compared to untreated specimens, pretreatment with formalin solutions increased the fluoride uptake in enamel and reduced the uptake in dentin. Only minor differences were found between specimens treated with unbuffered acid formalin solution and with buffered neutral formalin solution. Pretreatment with sodium lactate buffers increased F uptake in both enamel and dentin. Lowering of the pH in the lactate buffer resulted in a higher fluoride uptake in both tissues. A specific formalin effect seems to be responsible for the paradoxical reduction in fluoride uptake in formalin-treated dentin.