The Combination of Laser and Nanoparticles for Enamel Protection: An In Vitro Study.

Dental decay is caused by the fermentation of carbohydrates and the production of acids which demineralize teeth. The fermented food debris lowers the pH under 5.5, resulting in the mineral loss of teeth. Anti-decay factors are used to reduce decay rates and increase dental protection. Fifteen sectioned teeth samples were immersed in Ag NPs solution and then irradiated with laser pulses. Structures, morphologies, chemical compositions and microhardness were studied using the Vickers micro-hardness tester, energy dispersive x-ray machine, atomic force microscope and scanning electron microscopes. Nine mature extracted human third molars, cleaned and placed in plastic molds then filled with a warm epoxy resin, were sectioned longitudinally and polished. The samples were then cleaned ultrasonically and stored in distilled water and taken immediately one by one for laser treatment. Sharper, overlapping, interconnected rods and higher resistance against enamel decay were demonstrated with little alterations of the mineral percentages of the teeth samples. The combination of laser light and silver annoparticles improved the decay resistance; where regular inter-connected chain-like merged grains were formed. These laser-induced modifications in enamel components have reduced the lattice stress and enamel solubility and improved resistance against decay. The computer model indicated a possible prediction of the laser-treated profile prior to laser treatment.