Erbium laser ablation of dental hard tissue: Effect of water cooling

Background and Objective: Several lasers have been explored for hard dental tissue applications; used alone they have resulted in potentially harmful temperature increases in the pulp chamber. Materials and Methods: An Er:YAG laser (λ = 2.94 μm) was used to ablate hard dental tissues. Ablation rates with and without a water-cooling spray were measured. Subsequent experiments investigated the cooling effects of the water. Initially single channels were drilled into dentin; further studies involved ablating rectangular areas with repetition rates up to 10 Hz. Results: The water spray minimally reduced the ablation rates of dentin and did not affect the ablation rates of enamel. The water spray effectively cooled the teeth; while using the maximum average power investigated (10 Hz, 360 mJ/pulse), a water flow rate of 4.5 ml/min limited the temperature rise in the pulp chamber to less than 3°C. Conclusion: The studies confirm the feasibility of using an Er:YAG laser in conjunction with a water spray to safely and effectively remove hard dental tissues.