The Anatomy of a Tooth

Teeth are amazing tools! Besides giving you your unique smile, teeth enable you to speak clearly and to enjoy delicious food. At times it’s easy for us to forget how hard our teeth work and take them for granted, but how that changes when there’s a problem! Teeth don’t look complicated on the outside, but all 32 teeth have the amazing ability to perform for a life time. With good daily oral care…

Rooting it Out

Beyond the hard white business end (crown) we may not give much thought to what makes up our teeth. When they form, the root and crown develop separately. Cells already in position in the jaw create each two-layered root – dentin on the inside and cementum on the outside – but nobody knew which cells they were. Now, in mice, researchers have identified a group of cells bearing an active osterix gene, which make both layers. To complete their development a series of genes, including PTHrP, become active in these root cells. If PTHrP is stopped from working, teeth have much shorter roots and don’t erupt from the gums. Pictured are developing teeth, with the cells containing active PTHrP stained blue in a dense line at the under surface where the root will form. The next step is to figure out the role of PTHrP, and what other genes are involved.

Written by Esther Redhouse White

Image from work by Wanido Ono and colleagues

Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA

Image originally published under a Creative Commons Licence (BY 4.0)

Published in Nature Communications, April 2016

From Enamel to Root

The Anatomy of a Tooth Explained Your teeth are amazing tools! They give you a great smile, help you to speak clearly and to chew and enjoy delicious food. Sometimes though, we take our teeth for granted or neglect them until we have a problem or we are in pain. Teeth may look simple and humble on the outside, but a normal mouth has 32 teeth, all with the potential to last a lifetime. Your teeth…

Quick Tips – Common Questions: What can an anthropologist tell from the examination of teeth regarding either forensic identification of individuals or understanding past populations?

This is a Quick Tips post providing a basic answer to a commonly asked question often faced within the field of archaeology and anthropology.

An anthropologist can obtain a wide and varied collection of information from examining teeth. Information such as paleodiets and palaeoenvironments can be learnt from studying a population, or from studying an individual sample you can identify how old…

Regenerating Tooth Roots With Biomaterials

Several different types of stem cells can regenerate tooth enamel, but regenerating the tooth root has proven quite difficult.

As you can see from the image above, the tooth root is covered with a tough, fibrous covering called the cementum.  The cementum connects the tooth root to the alveolar bone of the upper and low jaw by means of the periodontal membrane.  the cementum is a thin layer of…

Walrus Ivory

This is a short section of walrus ivory. Note the indent running the length of the piece. This is a usual feature found on the inner portion of the tusk nearest to the animal. In noting a slight tapering on the right side, this is suggestive for this piece to be one of a left walrus tusk.

When viewing the cross-section of the walrus tusk, three layers are visible. There is the outer cementum, in the middle there is the primary dentin, and at the center, the secondary dentin. This inner layer is often noted to have a "grapey" appearance.

When creating tools, such as harpoon heads or drills, the best portion of the ivory to use is the primary dentin. This is the least brittle and most uniformly structured portion of the tusk. 

In cross-section, walrus ivory can be easily distinguished against mammoth ivory by the presence of Schreger Lines in the mammoth ivory. These are "V" shaped lines which appear at 90 degrees or less in mammoths, and greater than 115 degrees in modern elephants.

Mammoth ivory in cross-section: