Dental Tribune Canada

Researchers reveal proof for oldest known toothache

By Yvonne Bachmann, DTI
April 27, 2011

TORONTO, Canada/LEIPZIG, Germany: Not only humans, but animals too, have to deal with toothache once in a while. A team of researchers from the University of Toronto Mississauga has examined the jaw of Labidosaurus hamatus, a terrestrial reptile that lived 275 million years ago, and found evidence of bone damage due to oral infection. An evolutionary process may have increased the reptile’s susceptibility to oral infections.

The team of scientists, led by paleontologist Professor Dr Robert Reisz, whose research focuses on terrestrial vertebrates that lived around 250 to 315 million years ago, investigated the jaws of several well-preserved specimens of Labidosaurus hamatus. One specimen stood out because of missing teeth and associated erosion of the jaw bone. With the aid of a computer tomography scanning, Reisz and colleagues found evidence of a massive infection, which had resulted in the loss of several teeth, as well as bone destruction in the jaw in the form of an abscess and internal loss of bone tissue.

“The fossil was found in the 60’s, but remained unprepared until we did a thorough study of the anatomy of this important reptile. Labidosaurus is known mainly from Texas. The pathological specimen comes from there,” Professor Reisz, chair of the Department of Biology at the University of Toronto Mississauga, told Dental Tribune ONLINE.

Reisz and his team suggest that as ancestors of advanced reptiles adapted to life on land, many evolved dental and cranial specializations to feed more efficiently on other animals and to incorporate high-fiber plant leaves and stems into their diet. “The primitive condition, as seen in living amphibians and reptiles, is to have a continual process of growing new teeth in each socket. As these teeth grow, the old ones are gradually resorbed until they fall out, like our baby teeth,” Reisz told DT ONLINE. The primitive dental pattern in which teeth were loosely attached to the jaws and continuously replaced, changed in some animals. Teeth became strongly attached to the jaw, with little or no tooth replacement. This was clearly advantageous to some early reptiles, allowing them to chew their food and thus improve nutrient absorption. The scientists consider the abundance and global distribution of Labidosauris and its kin as an evolutionary success.

However, it is conceivable that the likelihood of infections of the jaw, resulting from damage to the teeth, increased substantially. Prolonged exposure of the dental pulp cavity of heavily worn or damaged teeth to oral bacteria was much greater than in other animals that quickly replaced their teeth. "Not only does this fossil extend our understanding of dental disease, it reveals the advantages and disadvantages that certain creatures faced as their teeth evolved to feed on both meat and plants," says Reisz.

The scientists have published their findings online in the magazine Naturwissenschaften – The Nature of Science (April). However, the fossil will not remain an object of study at the university, Professor Reisz says. “The specimen belongs to the Carnegie Museum of Natural History, and it will be returned to that institution. It will probably go back into the collections of the museum, but it may be shown in an exhibit sometime in the future.”

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