Formalin treatment of dentin, prior to burnishing demineralization, results in a tufted collagen surface that may optimize bonding of hydroxyethyl methacrylate dentinal bonding agents. The purpose of this study was to determine if there is a clinically acceptable formalin treatment time that will yield a deeply tufted collagen surface. The exposed dentin of periodontally healthy and periodontally diseased human teeth was treated with formalin for various treatment times before burnishing demineralization with citric acid. Photographs of the specimens revealed that there was a statistically significant difference in the number of tufted surfaces found in the healthy group, as a whole, and the number found in the diseased group. No statistically significant difference was found among fixation times within either tooth group. It was concluded that 2 minutes of fixation was sufficient to produce a tufted fibrillar surface.