Teeth have an increased resistance to environmental factors and decomposition processes, which makes them highly valuable in forensic investigations. The either physical (wind, water, sun, soil type) or biological (plant roots, insects, animals) environmental factors and the decomposition processes induce post-mortem changes in teeth, which are relevant to forensic investigation in terms of estimating the post-mortem interval or of elucidating the conditions in which the body stood after death. In this paper, based on the data provided in the literature, the authors present the main changes induced by environmental factors and decomposition processes in teeth and refer to their relevance in forensic activity.