Mammals, including humans, grow two sets of teeth in their lifetime. Baby teeth, or deciduous teeth, develop first and are replaced with permanent teeth. However, after the permanent teeth are lost, no additional teeth grow in to replace them. Artificial teeth, such as dentures, bridges or implants, can be used, but these measures are not as effective as natural teeth. In contrast, most lower vertebrate animals demonstrate continuous tooth generation. This means that they continually grow new teeth to replace any teeth they have lost.

Researchers at the University of Helsinki, along with collaborators from Germany and Japan, have shown the potential for continuous tooth generation in mammals. Working with a mouse model, the researchers activated a signaling pathway used for cell communication and embryonic development. The result was the induction of continuous tooth generation in one molar.

The mouse model grew a succession of dozens of fully developed teeth, complete with normal roots, dentin and tooth enamel. However, the crowns of the teeth were simple and cone-shaped. This structure is common in lower vertebrates with continuous tooth generation. Typical mouse molars are much more complex, with multiple cusps, similar in shape to the human molars.

Despite the early stage of this research, the scientists conjecture that it may be possible to trigger continuous tooth generation in humans, as well. If this potential is realized, dentists may eventually be able to induce the growth of new teeth in patients who have lost their permanent teeth.

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