A technique, sensitive enough to determine both dentinal and enamel abrasion in vivo, is presented. Computer-aided profilometry was used to measure the surface of dentinal and enamel samples before the experiment. Samples were subsequently placed in the buccal flanges of the mandibular dentures of two test subjects, who then brushed these pieces with a soft, multitufted brush, and two different toothpastes. Results of these pilot studies showed that the samples brushed with Colgate BiFluor had markedly less enamel and dentinal abrasion than did those brushed with Smokers. In addition, surface roughness was greater in the specimens brushed with Smokers. However, person-to-person variation can have a great influence on the abrasion process; moreover, only two persons were involved in this pilot study, and no definitive statement can be made about the effect of the toothpastes.