Root surface reactions to TiF₄ and SnF₂ solutions in vitro: An ultrastructural study

Abstract

Previous studies have indicated that TiF₄ and SnF₂ differ in their demineralizing effect when applied topically to root surfaces at the same acidity. The aim of this study was to examine in more detail the outermost layer of root surface specimens by transmission electron microscopy (TEM) after short-term exposure to these acidic fluoride solutions. Root surface specimens were exposed for 1 min and 4min to equimolar (1.1 MF) solutions of a) TiF₄, native pH 1.0; b) SnF₂, acidified to pH 1.0 and c) SnF₂, native pH2.5. The specimens were then rinsed in saline and processed for TEM. Exposure to TiF₄ resulted in a partly demineralized zone 8–10 μm deep after 1 min and 5–27 μm deep after 4 min of application. A 0.1-μm-thick, electron-dense coating was present in all TiF₄-treated specimens. Acidified SnF₂ resulted in a completely demineralized zone, 4–7 μm deep, when applied for 1 min and 4 min, whereas SnF₂ at native pH produced a 0.5- to 1.0-μm-wide partially demineralized zone. Unevenly distributed crystalline deposits were a frequent finding on SnF₂-treated surfaces. The results indicate that solutions of TiF₄ and SnF₂ at native pH will cause only slight demineralization when applied topically to root surfaces.

Key Words:

• Cariology
• demineralization
• fluorides
• topical
• transmission electron microscopy