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Most reptiles and fish have multiple sets of teeth during their lifetime. However, most mammals, such as humans, have only one set of replacement teeth and some mammals, like mice, have only a single set with no replacement. This diversity raises both evolutionary questions -- how did different tooth replacement strategies evolve? -- and developmental ones -- which mechanisms prevent replacement teeth in animals that lost them?
In a new paper in Development, Professor Abigail Tucker and PhD student Elena Popa of King's College London tackle these questions with a molecular analysis of mouse tooth development. They have pinpointed why mice don't have replacement teeth by comparing gene expression in the dental lamina, the area that forms the teeth, of the mouse and the minipig, which has two sets of teeth.
[...]Using sophisticated genetic techniques, the researchers activated Wnt signalling in the mouse RSDL at E15.5 and E16 stages of development, revitalising this structure, and additional teeth were formed as a consequence.
(Score: 2, Interesting) by Anonymous Coward on Saturday February 23 2019, @06:08AM (3 children)
They might like to peek in my DNA? Inherited from my father who had a similar problem, I'm missing four of my second set of teeth. There was nothing below/above to push out those baby teeth. One of the baby molars was tough, lasted until I was about 55 years old. The others came out sooner and were replaced with permanent bridges, touch wood, these are still working fine.
(Score: 1, Informative) by Anonymous Coward on Saturday February 23 2019, @10:50AM (1 child)
https://en.wikipedia.org/wiki/Hypodontia#Cause [wikipedia.org]
(Score: 0) by Anonymous Coward on Saturday February 23 2019, @01:10PM
Cool, thanks. Didn't realize this was common enough to have a name.
As noted further down the Wiki article, the orthodontist (twice) was expensive (and painful at times), but eventually fairly successful.
(AC GP)
(Score: 2) by Reziac on Monday February 25 2019, @10:02PM
And it can go the other way... We had a toy poodle who needed all her adult teeth pulled when she was about six years old. (And no, they were =not= leftover puppy teeth.) With a year or so she once again had a complete set of adult teeth, and these were still good when she died at age 14. Yep, this dog apparently had a complete third set of teeth, just waiting to pop out once the old ones were no longer in the way (and may have been why the previous set weren't well-rooted). Lots of toy dogs have extra teeth, but this is the only one I've seen with a full extra set.
And there is no Alkibiades to come back and save us from ourselves.