A new sealed RF-excited CO₂laser for enamel ablation operating at 9.4μm with pulse duration of 26 μs

Abstract

Several studies over the past 20 years have shown that carbon dioxide lasers operating at wavelengths between 9.3 and 9.6-μm with pulse durations near 20-μs are ideal for hard tissue ablation. Those wavelengths are coincident with the peak absorption of the mineral phase. The pulse duration is close to the thermal relaxation time of the deposited energy of a few microseconds which is short enough to minimize peripheral thermal damage and long enough to minimize plasma shielding effects to allow efficient ablation at practical rates. The desired pulse duration near 20-μs has been difficult to achieve since it is too long for transverse excited atmospheric pressure (TEA) lasers and too short for radio-frequency (RF) excited lasers for efficient operation. Recently, Coherent Inc. (Santa Clara, CA) developed the Diamond J5-V laser for microvia drilling which can produce laser pulses greater than 100-mJ in energy at 9.4-μm with a pulse duration of 26-μs and it can achieve pulse repetition rates of 3 KHz. We report the first results using this laser to ablate dental enamel. Efficient ablation of dental enamel is possible at rates exceeding 50-μm per pulse. This laser is ideally suited for the selective ablation of carious lesions.

Effect of laser pulse duration on ablation efficiency of hard bone in microseconds regime

“…Those studies have been extended together with the implementation of laser ablation in dentistry. 5,[10][11][12][13][14] Currently, the erbium-doped yttrium aluminium garnet (Er:YAG) pulsed laser has achieved the most successful results in dental surgery. [15][16][17] The Er:YAG laser used for dental applications works typically in the microseconds regime and has a wavelength of 2.94 µm.…”