Which statement best describes the primary interaction of lasers with dental hard tissue?

• A. They sterilize tissue by chemical reactions
• B. They achieve ablation primarily via thermal mechanisms
• C. They cut tissue mechanically with a blade
• D. They do not interact with water in tissue

Answer: (B)

Lasers remove dental hard tissue mainly through photothermal ablation. The energy from the laser is absorbed by water in the tissue (and to some extent by the mineral matrix), causing rapid heating, vaporization, and micro-explosions that drive material away. This thermal mechanism is what enables controlled, precise ablation of enamel and dentin when the laser wavelength and settings are chosen appropriately. The idea of sterilizing by chemical reactions isn’t the primary driver, and mechanical cutting isn’t how lasers work. In fact, water interaction is central to how most lasers interact with tissue, so saying there’s no interaction with water isn’t accurate.