Heterodont

"On the Homologies and Notation of the Teeth of Mammalia," by W[illiam] H[enry] Flower, F.R.S. […] The classification and special homologies of the teeth of the heterodont mammals was next discussed.

Source: wiktionary

The adaptation of the form of the teeth on both sides to this position, and the accurate adjustment of their contiguous surfaces, shows that it is a natural conformation. They are, moreover, of very nearly even height throughout the series, and in their configuration present a remarkable and gradual transition from the first incisor to the last molar, easily traced in both jaws, and more even and regular than in any other known heterodont mammal.

Source: wiktionary

The few common characters by which the Edentata are associated are too well known to need repetition. The principal one is the abseance of any trace of the typical heterodont and diphyodont dentition, found in a more or less modified form in all other placental mammals.

Source: wiktionary

[I]n many heterodont forms the teeth at the anterior end of the series of premolars and molars are small teeth, standing to the teeth behind them as the first terms of a series more or less regularly progressing in size.

Source: wiktionary