All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
15 05, 2013

Could Alligators Give us All “Crocodile Smiles”?

By | May 15th, 2013|Key Stage 3/4|Comments Off on Could Alligators Give us All “Crocodile Smiles”?

Stem Cell Research Provides Clues to Human Tooth Regeneration

Scientists from the University of California have identified the processes by which an Alligator is able to grow a replacement tooth if it loses one.  A better understanding of this at the cellular level could eventually lead to a radical reform of dentistry, with patients able to grow a replacement tooth should one have to be removed due to decay or trauma.

The Alligators used in the study (Alligator mississippiensis) are one of a number of extant, vertebrate genera that are able to replace teeth that are lost throughout their adult lives.  Reptiles and fish have this ability to regenerate teeth if they are lost and also dinosaurs had teeth replacement too.  Quite helpful if you are a seven tonne Tyrannosaurus rex with arms so tiny that they could not even reach their mouths to clean their teeth, had toothbrushes been around in the Late Cretaceous.

Tooth Replacement Frequently Observed in Fossils Representing Dinosauria

Illustration from Megalosaurus description.

Illustration from Megalosaurus description.

Picture Credit: Linda Hall Library of Science

The picture above shows the jaw of the first dinosaur to be scientifically described (Megalosaurus bucklandii), teeth erupting through the jaw bone can be clearly identified.

Using powerful microscopes, the Californian research team were able to identify a “family” of tooth components that made up the conical teeth of these predators.  There was the functioning tooth in the jaw, a replacement ready to erupt and a third element, the dental lamina.

A spokesperson from Everything Dinosaur commented:

“This is essentially a conveyor belt operation, as the functioning tooth is lost, then the other family members advance to ensure that the Alligator retains its bite.”

The dental laminae contains stem cells from which the teeth replacement function is initiated.  It is hoped that with a better understanding of this dentition, scientists may be able to isolate the stem cells and genetically combine them with tissue cells from the human jaw.  If this could be done, then it raises the possibility of human beings being able to grow replacement teeth, to give us all a “smile like a crocodile”.

To read more about this research: We Could All Soon Have the Smile of a Crocodile

15 05, 2013

We Could Have the Smile of a Crocodile

By | May 15th, 2013|Animal News Stories|0 Comments

Stem Cell Study of Alligators Provides Clues to Tooth Regeneration in Humans

A team of international researchers led by scientists at the University of California have been getting their teeth into the problem of tooth renewal in humans.  Their study of the toothsome American Alligator (Alligator mississippiensis), a reptile famed for its powerful bite may lead to the demise of certain aspects of dentistry, if a tooth is lost why not simply grow a replacement?

Could Alligators Hold the Key to Human Tooth Renewal?

Could Alligators give us all "crocodile smiles"?

Could Alligators give us all "crocodile smiles"?

One of the fascinating aspects of the Archosauria, that’s animals such as the dinosaurs and some of today’s living Archosaurs the Crocodilians, is these creatures’ ability to replace teeth that are lost throughout their adult lives. Reptiles and fish have the ability to regenerate teeth if they are lost.  For example, a Great White Shark (Carcharodon carcharias), has the ability to replace teeth that are lost.  Dinosaurs are sometimes referred to as “land sharks”, because they too, had this impressive ability.  Good news for both the sharks and the Tyrannosaurids for example.  After all, if T. rex lost teeth either fighting or feeding then being toothless would have been a very serious and fatal drawback.  Nobody is going to watch “Jurassic Park” to see a fourteen metre long apex predator lick its victims to death.

Fish and reptiles have the ability to regenerate teeth that have been lost, mammals on the other hand have much more limited dental options.  Humans for example, can renew their dentition just once, (milk teeth replaced by adult teeth).  In essence, our species has just two sets of teeth for a lifetime (diphyodont dentition).  However, new research involving the microscopic study of the structure of Alligator teeth could help scientists to learn how to stimulate tooth regeneration in humans.  The research team led by pathology Professor Cheng Ming Chuong (University of Southern California), have discovered unique cellular and molecular processes which permit tooth renewal in the American Alligator.  The academic paper detailing this new research has been published in the “Proceedings of the National Academy of Sciences”.

One of the Lead Members of the Research Team Professor Cheng Ming Chuong

Lead author of the scientific paper Professor Chuong

Lead author of the scientific paper Professor Chuong

Picture Credit: University of Southern California

Professor Chuong commented:

“Humans naturally only have two sets of teeth — baby teeth and adult teeth.  Ultimately, we want to identify stem cells that can be used as a resource to stimulate tooth renewal in adult humans who have lost teeth.  But, to do that, we must first understand how they renew in other animals and why they stop in people.”

Mammals evolved from reptiles, our species shares a common ancestor with the American Alligator.  We may look very different from the scaly crocodiles with their impressive teeth, but there remain similarities.  For example, like the Alligator, our teeth are implanted in sockets in the dental bone.  In the human jaw there is the lingering presence of a band of epithelial tissue referred to as the dental lamina.  This same type of epithelial tissue was found to be present within the components that make up each tooth of an Alligator.  Epithelium tissue is one of four types of tissue found in the higher Animalia (muscle, connective, epithelium and nerve tissue).  This band of epithelial tissue is crucial to tooth development and growth, the research team reasoned that because Crocodilians have well organised teeth with a similar form and structure to our own, their dentition would make a suitable model for studying the process of tooth replacement with the objective of finding ways in which humans could grow replacement teeth.

Some Structures and Components of Crocodilian Dentition are Similar to Mammalian Dentition

Scientists research the dentition of Crocodilians.

Scientists research the dentition of Crocodilians.

Assistant Professor of Pathology at the Keck School of Medicine Ping Wu, stated:

 “They [Alligators] have eighty teeth, each of which can be replaced up to fifty times over their lifetime, making them the ideal model for comparison to human teeth.”

Under microscopic investigation, the authors of the scientific paper found that each separate Alligator tooth is actually a complex “family” of three tooth components, the functional teeth in the jaw, a replacement tooth ready to erupt to replace the tooth if and when it is lost and the dental lamina.  In essence, each tooth has components at different stages of development, tooth replacement is essentially a “conveyor belt operation”, as one member of the Everything Dinosaur team commented.  There is a smooth transition from the loss of a mature tooth to its replacement and the dental laminae seems to hold the key to this process.

Microscopic Analysis of Alligator Teeth Reveal Complex “Family of Components”

Research into Alligator tooth regeneration.

Research into Alligator tooth regeneration.

Picture Credit: University of Southern California – Health Sciences

University of Southern California researchers identified three developmental phases for each alligator tooth unit, comprising a functional tooth (f), replacement tooth (r) and dental lamina.  The two-headed arrow provides orientation in the mouth, the buccal direction is towards the cheek, the lingual direction is towards the tongue.

The research team have concluded that the Alligator dental laminae contains what appear to be stem cells from which new replacement teeth develop.

Co-author of the study, Associate Professor Randall B. Widelitz explained:

“Stem cells divide more slowly than other cells.  “The cells in the Alligator’s dental lamina behaved like we would expect stem cells to behave.  In the future, we hope to isolate those cells from the dental lamina to see whether we can use them to regenerate teeth in the lab.”

The researchers went onto demonstrate that tooth growth is speeded up by novel cellular mechanisms in response to unexpected, premature tooth loss.  Although, growing human teeth to replace adult teeth lost in trauma or as a result of disease is a long way off, the authors of this paper hope to apply the principles of Alligator tooth renewal to regenerative medicine in the future.

Perhaps dentures will be redundant in the future, we will all have “crocodile smiles” instead.

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