Mechanisms by which titanium tetrafluoride (TiF4) reduces enamel solubility were investigated. An association was found between solubility reduction and the formation of a glaze on the enamel surface. Also, TiF4-treated enamel had higher levels of fluoride than enamel treated with acidulated phosphate-sodium fluoride. Solubility reductions and fluoride levels decreased slightly with washing but after 48 hours the fluoride level was still 60% of the maximum, and solubility reductions ranged between 64 and 70%.In previous work,' it was shown that titanium tetrafluoride (TiF4) treatment of enamel gave greater reductions of enamel solubility and greater protection against animal caries than did comparable use of other fluorides. These indications of the potential caries-preventive value of TiF4 prompted further study of its effects on enamel. During these latter studies, we observed that TiF4-treated enamel often acquired a glazelike appearance. This raised the question of the extent to which the uniquely high solubility-reducing effect of TiF4 might be dependent on reactions associated with the "glaze" formation or on the fluoride content of TiF4-treated enamel.To obtain information on these questions, experiments were undertaken to indicate the conditions under which the TiF4 glaze formed on enamel, the fluoride content of TiF4-treated enamel, and the relationship of these to the observed reductions in enamel going into solution. Materials and MethodsIn vitro effects on enamel dissolution were measured by the previously described' 'window' technique, in which windows made on unground bovine enamel surfaces are exposed to a series of 15-minute acid decalcifixations in 20 ml 0.1 M acetic acid buffer (HAc), pH 4. The difference in amounts of phosphorus2 in the decalcifying buffer before and after treatment of the enamel with TiF4 or other agents gave a measurement of effects on enamel solubility.The glaze that appeared on the enamel, particularly after topically applied TiF4 followed by application of 0.1 M HAc, was given a visual rating of from 0 to ++++. This glaze produced seemingly whiter enamel and appeared on ground and unground human enamel, and on unground bovine enamel surfaces.To obtain information on the factors influencing glaze formation and the extent to which the glaze determined solubility reduction, glazes of different grades (0 to ++++) formed under various conditions were compared with solubility findings. For this purpose, different agents were used with TiF1 on normal bovine enamel, ethylenediamine-extracted "anorganic" enamel, and "organic-exposed" enamel. The ethylenediamine (ED)-extracted enamel was prepared by refluxing for 2.5 or 20 hours in a Soxhlet apparatus at 118 C.3 Organic-exposed enamel refers to the incompletely EDextracted enamel4 that was etched for two minutes with 0.3%l HCl, thereby exposing the underlying organic material in the partially anorganic enamel. Solubility changes were measured by the window technique.To indicate whether the high solubility reductions given by TiF4, w...

No abstract

No abstract

By comparing phosphorus loss from enamel windows during successive exposures in acetic acid buffer, measurements were made of the effects of a number of uncommon fluoride and nonfluoride compounds on enamel dissolution. Acidulated ytterbium chloride and the tetrafluorides of titanium, zirconium, and hafnium gave much more lasting protection against the action of acid than did the fluorides commonly used for caries prophylaxis.

An annual, one-minute application of a 1% solution of titanium tetrafluoride to the teeth on one side of the mouth of each of 110 children offered greater protection against caries after three years than was given to teeth on the other side of the mouth treated with a four-minute application of acid phosphate fluoride.