Fundamental Interactions of Laserswith Dental Hard Tissues

Abstract

Summary In order to choose the laser conditions that will be best suited for a particular application in dentistry, knowledge of the fundamental interactions of lasers with the tissues is necessary. Lasers interactions with tissue are complicated and no single parameter alone will determine how the laser affects the tissue. Dental hard tissue applications include ablation of carious lesions, cavity preparation for restoration, caries detection, endodontic surgery, and the potential for caries preventive therapy. The parameters of prime concern in understanding desirable or undesirable tissue effects are wavelength, pulse duration, absorption properties, scattering, energy, fluence (energy/surface area), power density, repetition rate, number of pulses, pulse duration and pulse shape. A range of laser parameters has been found with which dental enamel can be treated to make it resistant to subsequent dissolution by acid during dental caries. Our studies have demonstrated that treatment of enamel by specific pulsed carbon dioxide laser irradiation can markedly inhibit subsequent caries progression. During irradiation, heat causes carbonate loss from the carbonated hydroxyapatite mineral, converting it into a low solubility hydroxyapatite-like calcium phosphate. By carefully choosing the parameters it is possible to produce a laser that can selectively remove carious tissue, leading to a conservative cavity preparation, and also providing protection against later caries challenges.