EFFECTIVE LASER-ABLATION OF ENAMEL AND DENTIN WITHOUT THERMAL SIDE-EFFECTS

We present a feasibility study into laser treating dental materials by using femtosecond pulses generated by a titanium:sapphire laser syste m which consisted of an oscillator and a regenerative amplifier. The p ulse duration was varied between 200 fs and 2 ps. The observed energy thresholds for the ablation process of dentine and enamel mere clearly smaller than those observed when longer pulse durations were used. Th e consequence of this observation is a lower thermal load within the v icinity of the radiated area. Thus no thermal damage or mechanical dam age, such as cracks, were produced during the laser treatment. Commerc ially available femtosecond laser systems can produce ablation rates i n healthy and in-vitro demineralized dental material of 2 mm(3) per mi n and 6-16 mm(3) per min, respectively. These values are an order of m agnitude larger than those produced by picosecond laser systems at the same pulse energy and pulse repetition rate. The brightness of the pl asma spark generated by the laser treatment depended on the extent of the demineralization of the teeth. This may allow online control of th e laser treatment.