Nano Biomedicine
ORIGINAL ARTICLE

Morphological and Chemical Changes Induced by Acidulated Phosphate Fluoride Application on the Surface of Bovine Enamel Treated with 5% EDTA

Tomoharu OKAMURA1, Takehiro YOSHIKANE1, Katsuhiro SUZUKI1, Airi UEDA1,
Yukino HISANO1, Chihoko IKEDA1, Sho AOKI2, Yoko ABE2, Yasutaka KAIHARA2, and Kazuya TOMINAGA1


1Department of Oral Pathology, Osaka Dental University, Osaka, Japan
2Department of Pediatric Dentistry, Osaka Dental University, Osaka, Japan
Nano Biomed 2026; 18(2): 21-30, (Jun 30, Nano Biomedicine)
Synopsis
In this study, we morphologically and chemically examined microstructural changes on the surface of bovine enamel demineralized with ethylenediaminetetraacetic acid (EDTA) , as well as changes induced when acidulated phosphate fluoride solution (APF) was reacted with the demineralized enamel. When enamel was exposed to 5% EDTA for 15 or 30 min, the interprismatic substance in the superficial enamel layer disappeared, and enamel prisms composed of needle or rod-shaped hydroxyapatite crystals were exposed. When APF was reacted for 2 or 20 min, cuboid-like or spherical-like calcium fluoride-like structures were formed and filled the voids that had disappeared due to EDTA. As the reaction time with APF increased, these structures became larger cuboid-like or spherical-like crystals, which was mor-phologically observed by scanning electron microscopy (SEM) . Energy dispersive X-ray spectroscopy (EDS) showed fluorine binding with a heterogeneous distribution on the enamel surface; regardless of APF reaction time, it was observed that calcium fluoride-like structures were not formed uniformly over the entire enamel surface. From the morphological and chemical observations, it was suggested that the APF used in this study repaired microscopic substance defects in enamel with a 2 min application.

Key words APF, EDTA, calcium fluoride, microstructural repair, elemental mapping
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DOI: 10.11344/nano.18.21

Okamura T, Yoshikane T, Suzuki K, Ueda A, Hisano Y, Ikeda C,Aoki S, Abe Y, Kaihara Y, Tominaga K. Morphological and chemical changes Induced by acidulated phosphate fluoride application on the surface of bovine enamel treated with 5% EDTA. Nano Biomed 2026; 18(1); 21-30.