CO sub(2) laser irradiation enhances CaF sub(2) formation and inhibits lesion progression on demineralized dental enamel-in vitro study

• Published in: Lasers in medical science Vol. 31; no. 3; pp. 539 - 547
• Main Authors: Zancope, Bruna R, Rodrigues, Livia P, Parisotto, Thais M, Steiner-Oliveira, Carolina, Rodrigues, Lidiany KA, Nobre-dos-Santos, Marines
• Format: Journal Article
• Language: English
• Published: 01.04.2016
• Subjects: Calcium fluoride; Demineralizing; Enamels; Irradiation; Lasers; Lesions; Progressions; Uptakes
• ISSN: 0268-8921; 1435-604X
• DOI: 10.1007/s10103-016-1900-4

This study evaluated if Carbon dioxide (CO sub(2)) ( lambda 10.6 mu m) laser irradiation combined with acidulated phosphate fluoride gel application (APF gel) enhances "CaF sub(2)" uptake by demineralized enamel specimens (DES) and inhibits enamel lesion progression. Thus, two studies were conducted and DES were subjected to APF gel combined or not with CO sub(2) laser irradiation (11.3 or 20.0 J/cm super(2), 0.4 or 0.7 W) performed before, during, or after APF gel application. In study 1, 165 DES were allocated to 11 groups. Fluoride as "CaF sub(2) like material" formed on enamel was determined in 100 DES (n=10/group), and the surface morphologies of 50 specimens were evaluated by scanning electron microscopy (SEM) before and after "CaF sub(2)" extraction. In study 2, 165 DES (11 groups, n=15), subjected to the same treatments as in study 1, were further subjected to a pH-cycling model to simulate a high cariogenic challenge. The progression of demineralization in DES was evaluated by cross-sectional microhardness and polarized light microscopy analyses. Laser at 11.3 J/cm super(2) applied during APF gel application increased "CaF sub(2)" uptake on enamel surface. Laser irradiation and APF gel alone arrested the lesion progression compared with the control (p<0.05). Areas of melting, fusion, and cracks were observed. CO sub(2) laser irradiation, combined with a single APF application enhanced "CaF sub(2)" uptake on enamel surface and a synergistic effect was found. However, regarding the inhibition of caries lesion progression, no synergistic effect could be demonstrated. In conclusion, the results have shown that irradiation with specific laser parameters significantly enhanced CaF sub(2) uptake by demineralized enamel and inhibited lesion progression.