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:

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Modern elephant ivory in cross-section:

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Factors That Cause Periodontal Disease
Tuesday, August 21, 2012 - Dental Health with Dr. Patel by Dr. Priya Patel


To understand what periodontal disease is, you need to first understand what the periodontal tissues are. The tissues which surround and support our teeth are periodontal tissue. There are four types of tissues which make up periodontal tissue. They are as follows:

  • Cementum
  • Alveolar bone
  • Periodontal ligament
  • Gingivia (gums)

When a person suffers from periodontal disease, it means that one or more of the periodontal tissues’ has been affected with disease.

The problem of periodontitis begins with plaque. It is a sticky and visible film which forms a layer on your teeth from the starches and sugars which are present in food interacting with the bacteria in your mouth. It is seen as the yellow soft deposit on teeth that is normally easily removed by good and effective brushing.

Even though you brush your teeth to remove plaque, it has the tendency to reform itself. This takes place within 24 hours. A plaque which happens to stay on or within your teeth for two or more days can cause a serious damage. This plaque can become firm along and under your gum line. This converts itself into tartar (also known as scale or calculus). Tartar is that hard chalky substance that forms around your teeth. With time it becomes difficult to remove by brushing. It also acts as the live reservoir for your mouth bacteria.

No matter how you brush and floss and no matter how expensive the tooth cleaning products you buy, you might not be able to get rid of all the accumulated tartar on your own. You will need to opt for professional cleaning like that from a dentist or hygienist if this is the case. 

As clarified above the more time you allow the plaque or tartar to stay on teeth, the more you invite them to complicate your case.



It begins with slight irritation around your gums. You may soon experience inflammation around your gingiva, which is the gum that supports your teeth. Ginigivitis is the inflammation of the gums. It can be painful and present with swelling and bleeding (if you are a non-smoker).


Continuous inflammation leads to the development of pockets between your teeth and gums. These pockets soon fill up with bacteria, plaque, tartar and food. The longer you leave it untreated, the deeper the pocket becomes. This will allow accumulation of more and more bacteria. The pockets advance to damage the tissues which are under your gums. Once the tissues under your gum are damaged the condition becomes infectious. This may result in either the loss of your tissue or your bone. This means you have the chance of losing one or more teeth.

It is safe to say that the entire cycle of accumulation of plaque, conversion into tartar, leads to periodontal disease. But there are other aspects to this problem as well. Here is a brief look at the contributors to periodontal disease.

Contributors to periodontal disease:


Tobacco, either in the form of chewing tobacco or smoking, is the most well known contributor to periodontal disease. With the constant use of tobacco you allow your immune system to grow weak day by day. It also sets up an environment that is conducive for harmful bacteria to generate and multiply.

Your mouth has an inbuilt mechanism to fight and limit the growth of bacteria in your mouth. But with the consumption of tobacco you allow it to interfere in the natural process to fight back the bacteria. So even if you get treatment for periodontal disease, you will not be able to respond well.


If you take tablets for colds or coughs or any other in general on a regular basis then you have landed yourself in a little trouble. Your bacterial levels will be affected. Continuous consumption of tablets can lead to over growth of your gum tissues. This makes it difficult to remove tartar or plaque and later results in periodontal disease. Some prescribed medicines can also have a negative on the health of your gums causing gum inflammation or a dry mouth.


There are numerous health complications which can result in periodontal diseases. They take a serious toll on the gums and lead to many complications. Diabetes is one of them. Diabetics are naturally vulnerable to infections. If you are diabetic and have periodontal disease then it will affect your body’s ability to heal. People who suffer with heart problems also have been found to suffer with periodontal disease.

Any individual who has an imbalanced diet or are malnourished are susceptible to this disease. Usually it is the lack of following things which results in nutritional deficiency:

  • Vitamin B
  • Vitamin C
  • Calcium

Calcium is the main source which allows strength not only to the teeth but also to bones.

No matter how much extra care you take of your teeth. It is wise to plan your dental check-ups regularly.

Read more: Factors that cause periodontal disease | Washington Times Communities

Moment of Tooth

If nothing else, the scanning electron micrograph above of a human tooth should encourage proper oral hygiene. While you’re at it (remember to brush for at least two minutes and don’t overlook those back molars), here’s a little some mental floss about those choppers:

  • Tooth enamel is almost entirely comprised of minerals – 96 percent, primarily hydroxylapatite  – with the rest being water and organic materials. It’s considered the hardest and most enduring substance in the human body, which is why it is frequently the only fossilized evidence left of extinct species.
  • Enamel is translucent and varies in thickness from 2.5 millimeters, about half the thickness of a nickel, to very, very thin where meets the cementum, which coats the root of the tooth. Dentin makes up the bulk of each tooth and is responsible for their color.
  • Researchers in China have successfully grown a human tooth using stem cells derived from urine. The purported goal is to one day be able to grow replacement teeth lost to aging or poor hygiene.
  • Researchers are using teeth from children with autism, courtesy of the “tooth fairy,” to create induced pluripotent stem cells to study the condition.
  • Americans spend $1.7 billion annually on teeth whitening products.
  • The ancient Mayans of roughly 2,500 years ago weren’t much into whitening their teeth but they did want them to look pretty - so they used primitive drills to make small holes into which were fitted gemstones. The practice was limited to the wealthy and, interestingly, mostly to men.

When do we overbrush our teeth?

1. Brushing Too Often
Ideally your dentist wants you to brush three times a day, after every meal. At the very least professionals suggest you brush once after breakfast and once before bed. But what if you eat six small meals a day? Should you still brush after every meal and every snack and every sip of coffee? This is where misconceptions about brushing teeth start to arise.

2. Brushing Too Vigorously
Many dental patients attack their teeth with their toothbrushes, thinking they are getting rid of plaque hard and fast. But being over-zealous with your toothbrush does not remove any more plaque. Matter of fact, it starts harming the gum tissue and exposes the tooth root. Here the dentin is not protected by enamel, but rather a thin layer of cementum. Excessive or improper tooth brushing is liable to abrade these substances and do permanent damage.
Right-handed patients tend to press harder when brushing the teeth on their left hand side. On the pictures you can see enamel lesions and gum recession caused by right-handed patients overbrushing their teeth.

3. Brushing With the Wrong Toothbrush
Plaque is fairly soft. You could remove it with a damp cloth, if that could reach all the nooks and crannies where it hides. But once plaque hardens into calculus (tartar), the only way to remove it is with professional help from a dentist or hygienist. This is why there is not any extra benefit to using a hard bristle brush. The best manufactured toothbrushes have soft or medium nylon bristles. If you were to check these out under a microscope you would see they have rounded edges, instead of flat. This cuts down on the abrasiveness while still allowing the bristles to clean along the gumline and in the crevices of teeth.
In some Muslim cultures it is highly recommended the use of a tree toothpick called miswak. It is even mentioned in their sacred book of Quran that the use of miswak ‘purifies the mouth’ and it is quoted by the Islamic prophet Muhammad himself. However, science has proven that the long term use of miswak can cause gum recession and abrasion lesions on the buccal surface of the teeth.

4. Brushing With the Wrong Toothpaste
Toothpastes contain minor abrasive substances to remove plaque and superficial stains from teeth. Under normal use, toothpaste helps clear away plaque and food particles, but leaves the enamel and dentin intact. Researchers say it would take 80 to 100 years to remove just 1mm of exposed dentin. Enamel, as a much harder substance, would remain intact. However, not all toothpastes are created equal, especially those you might make at home. Abnormal or abusive brushing with abrasive toothpastes might not have much effect on the enamel. But it could dramatically impact the soft tissue and any exposed dentin.

5. Brushing Too Soon
Acid is the most harmful substance for the enamel. So if you brush right after having highly acidic foods or beverages, the enamel has not had enough time to naturally recover. It is more susceptible to damage caused by overbrushing.



Age-at-death estimation of pathological individuals:
A complementary approach using teeth cementum annulations

  • by B. Bertrand, G. Robbins Schug, C. Polet, S. Naji and T. Colard

“Bioarchaeologists rely on accurate estimations of age-at-death. Clearly, some pathological conditions are associated with gross morphological changes in the skeleton that could impact the effectiveness of age-at-death estimation (i.e. methods based on the pelvis, fourth rib, dental attrition, and cranial stenosis). The magnitude of this problem has not been widely studied due to a paucity of pathological skeletons of known age. We assessed age-at death for three individuals affected by bone dysplasias (achondroplasia, residual rickets, osteogenesis imperfecta) using cementum annulations and several osseous age indicators. We predicted osseous indicators that are based on gross morphological changes would yield age estimates discrepant from the cementochronology. Results demonstrated considerable differences in age estimates between morphological and histological techniques suggesting a need for additional research on the effects of pathology on the accuracy of morphological methods. Conversely, we addressed the proposition that cementum annulations will be inappropriate for age estimation in cases of chronic and severe rhino-maxillary infection and periodontitis. We assessed age-at-death for one individual with leprosy and found no indication the disease process affected cementum formation or preservation. The results of this research indicate the potential value of cementochronology in cases where skeletal pathological conditions constrain the usefulness of traditional age estimation approaches” (read more/open access).

(Open access source: International Journal of Palaeopathology, in press 2014 via Academia.edu)