Increase of enamel fluoride retention by low fluence argon laser in vivo

The aim of this in vivo study was to investigate if argon laser irradiation of enamel can increase the retention of fluoride.

Ninety-eight teeth in 12 patients were randomly divided into three groups: (1) EF group: 40 teeth were only treated by fluoride gel (application for 5 minutes followed by 1 minute rinsing with distilled water). (2) EFL group: 40 teeth were treated the same way as in the EF group but they were lased after fluoridation. (3) E group of 18 teeth were kept without any treatment and considered as reference. In order to quantify the fluoride content in the enamel samples, the teeth were analyzed by proton beam delivered by a tandem accelerator (PIgammaE, particle induced gamma-ray emission). The fluoride content of enamel surface is not homogeneous. Therefore, it is necessary to analyze the same enamel area after each treatment. Each tooth was maintained in a fixed tooth holder which was designed to analyze the tooth enamel surface at the same place (1 mm(2) and around 20 mum in depth) after various treatments. A low energy density of argon laser beam was used: 10.74 J/cm(2), 30 seconds of irradiation time and 340 m W of output power.

The results after 7 days showed that the lased enamel still retained 157.4 +/- 23.371 ppm or 42.29% of fluoride after fluoridation process whereas the unlased enamel retained 45.59 +/- 9.377 ppm or 12.25% of fluoride.

We concluded that the use of argon laser at low energy density (10.74 J/cm(2)) significantly increases the fluoride retention in lased enamel which had approximately three times more fluoride than the unlased enamel.