The proteins were sequentially extracted with guanidinium chloride (G1-extract) and then with EDTA. After demineralization, the material was again extracted with guanidinium chloride (G2-extract). The research used SDS-PAGE electrophoresis to analyze the extracts and then processed the gels for zymography to detect gelatinolytic activities. The patterns of gelatinase A distribution differed in the different dentin protein fractions, and the changes varied with age. Significant differences existed in gelatinase A in G2-extracts between individuals younger than 20 years old and the rest of the sample. The research also calculated the incidence of true and false positives and negatives, as well as the sensitivity and specificity for the presence of gelatinase A in dentin extracts. Findings indicated that the determination of gelatinase A in human dentin may be a useful marker to estimate age, especially when other morphological methods are of limited usefulness. Figures, table, and 33 references (Author abstract modified)