The invention relates to methods and apparatus for processing biological tissue and dental materials which involves providing or distributing a substance containing abrasive particles to an area in front of at least a portion of a surface of the tissue/material and irradiating both the substance and the portion of the surface with light from a selected source, the light being selected and delivered in a manner such that selective ablation is caused on the substance sufficient to force the abrasive particles under a selected pulse against the portion of the surface. Ablation may be of the particles themselves or the particles may be contained within a shell, with ablation being of the shell. The substance is preferably delivered as a series of distribution pulses with the light being delivered either continuously or as light pulses having a predetermined relationship to the distribution pulses.