Sounds Fishy, But Tooth Enamel Seems To Have Evolved From Fish Scales

And you have to wonder who made the correlation between the fine, fingernail-like scales of fish, and the hardest substance of the human body.

For those not in the know, it isn’t bone and it isn’t even teeth: it’s the enamel that covers them, and makes them look white.
Without it, teeth can’t withstand the normal forces of biting and chewing. Lacking this protective coating for the soft and sensitive dentin that interacts with tooth nerves would be intensely painful; even moreso with the rapid onset of decay and dental deterioration.
Enamel hypoplasia is the rare condition in children where teeth develop without it.

It occurs prior to the tooth erupting when specific cells are damaged or disturbed through reason of genetics or environment. In severe cases there is no enamel; generally however, it’s fragile and thin. The range of treatments include remineralisation, sealants, tooth-coloured fillings and dental reconstruction (as in crowns). Early detection and diagnosis is crucial, as it can effect permanent teeth as well as milk teeth.

Unrelated to this hypomineralisation but still on the scale of weird, is one of the fragrances of French perfumier, photographer and aesthete, Serge Lutens. Dent de Lait is a scent meant to smell like teeth.

The direct translation of its name to English is ‘milk tooth’ and it’s an attempt to somehow encapsulate the olfactory stamp of the loss of the first tooth in childhood. Bizarre on too many levels to feasibly address here. (“Why?” and “who would want to smell like that?” are just the beginning.) Along with apparently having a “metallic tinge” base note, it has been described as smelling like “warm, powdery, milky hard candy you might have received as a child from a grandma or great-aunt.”

For that to relate to the scent memory of gearing up for the first Tooth Fairy’s visit brings the macabre thought that grandma, or that not-so-great great-aunt, slapped it out of your head and jammed a gob-stopper in there to stop the screaming.

Maybe that’s part of Lutens’ tragic and fascinating past. With more than a hundred scents to his entirely unisex collection, he is the grandaddy of niche perfumery with a penchant for the inexplicable. De Profundis is fragrant of “a graveyard in autumn”. When author and one-time Hermès nez Jean-Claude Ellena made the succinct observation that “Smell is a word, perfume is literature” is life as such a fast, fast moving sensorial torrent it has to snag us between realities to get our attention.

Why else would we want to know how a fish scale is the reason we can strip a chicken bone clean, sing ‘Blister in the Sun’ and smile because life’s a beautiful thing?

With apologies to The Marvelettes, coelacanths were once thought to be the ‘missing link’ between too-many-fish-in-the-sea and tetrapods, before lungfish turned out to be the winner there.

Scientists had always been unclear about whether enamel originated in teeth, or evolved from ganoine – an enamel-like tissue found on the scales of fossil fish and present day (puny numbered) coelacanths.

Researchers examined the fossils of two primitive bony fish from the Silurian Period; a time of remarkable evolution and diversification in marine life that stretched over 24.6 million years. To their surprise, they found scales coated in enamel, but not teeth. It had always been a scholarly expectation that because enamel is so intrinsic in the functioning of teeth that it would have evolved from there – not from the scales of the skin of ancient fish.

Fish have mineralised tissue as well. In some species it’s found in two places: their teeth, and the spines on their skin. Known as ‘denticles’ they’re what makes shark skin rough in one direction, and smooth in the other.

Modern bony fish have teeth but no denticles. Their teeth are coated in acrodin, not enamel. The oldest major class of living fishes – sharks and rays – have both teeth and denticles, and again, no enamel. They have enameloid, which sounds like angry enamel. Of course it isn’t; but a shadow is cast when another term for it, ‘vitrodentine’ has a toothy tail end and a prefix two letters short of bitter.
So in this whale of a tale there’s no enamel anywhere. Until the coelacanths come along. They have enamel everywhere. (Not exactly everywhere; just everywhere the others don’t.)

The inclusion, evolution and confusion of dental enamel lies between teeth and denticles. To add fuel to the fry-up, humans have denticles too – in tooth pulp. Related? On a molecular level, yes.

Gene evidence suggests that way, way before the Baby Shark Song annoyed everyone to death, somewhere between the rise of sharks and modern bony fishes, fish developed the ability to make enamel. Then for some reason they lost it, while tetrapods and coelacanths retained it.

The conclusion is that the first true enamel evolved in skin before it spread to the head, and then settled in the mouth. Once teeth emerged in the earliest fish, skin and teeth went their separate evolutionary ways. Bony fishes lost their enamel, evolved other tooth materials and kept their denticles.Tetrapods climbed onto land, kept their enamel teeth and lost their denticles.
Fishy, huh. Literally off the scale.

BOOK NOW

Note: All content and media on the  Sunbury Dental House website and social media channels are created and published online for informational purposes only. It is not intended to be a substitute for professional medical advice and should not be relied on as health or personal advice.

Services Mentioned