CO<sub>2</sub>レーザー照射とグラスアイオノマーセメントによる象牙質の再石灰化

Abstract

We investigated the effects of CO2 laser irradiation combined with immersion in a solution containing fluoride ions on the remineralization of etched dentin surface. Human premolars were divided randomly into four groups (1, control: NL; 2, immersion in fluoride-ion-containing solution: NLF; 3, laser irradiation: L; 4, laser irradiation plus immersion in fluoride-ion-containing solution: LF). Embedded human dentin blocks were etched with phosphoric acid, fixed on a specimen stage, and then a CO2 laser (10.6-µm wavelength) was applied (15 W/cm2), followed by immersion in fluoride-ion-containing solution. Nanoindentation testing was carried out before and after CO2 laser irradiation and during the immersion period, and then the dentin surfaces were observed by scanning electron microscopy. Phosphoric acid etching markedly decreased the mechanical properties (hardness and elastic modulus) of dentin surfaces. The mechanical properties of the etched dentin specimens subjected to laser irradiation plus immersion in fluoride-ion-containing solution recovered significantly during the immersion period compared to those of the other specimens. After immersion for 1 month in the fluoride-ion-containing solutions (NLF, LF), the wide-open dentinal tubules caused by acid etching were partly filled by a remineralized layer. In conclusion, CO2 laser irradiation with low output plus immersion in fluoride-ion-containing solution may enhance the remineralizing ability of etched dentin surface.