Teeth Anatomy

This article was originally published on mouthpower.org

Knowing just a little bit about teeth anatomy can help you maintain good oral health. If you understand how the teeth are structured and what they are made of it is easier to appreciate how problems like tooth decay, sensitivity, gum disease, teeth staining and bad breath occur.

TEETH STRUCTURE

The human tooth is a complex structure that is made up of multiple layers of organic and inorganic matter. Organic tooth matter refers to the living parts of the teeth that consist of cells, fibers, proteins, and water. The inorganic matter is mainly composed of calcium salts and provides the strength and substance of the teeth.

Each tooth can be divided into three sections which are called the crown, neck, and root. The crown is the visible part of the tooth that we see above the gum line.The bulk of the crown structure is made from dentin and it is covered by a protective layer of enamel.

The roots of the teeth are hidden in the gum tissue and bone and are surrounded by cementum. The crown of the tooth and the root come together at the neck.

The four main parts of the teeth are the enamel, dentin, cementum and pulp cavity. Each part has unique characteristics and a different combination of organic and inorganic matter. The enamel, dentin and cementum layers are all mineralized to varying degrees and the pulp cavity is soft tissue which comprises of blood vessels, nerves, and connective tissue.

To understand the different layers better, let’s have a look at them individually.

ENAMEL

Enamel is made up of 4% organic and 96% inorganic matter and it covers and protects the crown of each tooth. The main inorganic material in enamel is hydroxyapatite, which is a crystalline calcium phosphate.

Facts about enamel.

Enamel is:

• The hardest material in the human body.
• Semi-translucent.
• Brittle and can become fractured if the dentine layer becomes decayed and weakened.
• Unresponsive to external stimulus like heat, cold, sweet and sour.
• Susceptible to staining and discoloration from highly pigmented foods and beverages.
• Subject to a constant demineralization and remineralization process (click here for more information).
• Weakened by acidic conditions. If the pH of the mouth falls to below pH 5.5 then calcium phosphate will be dissolved from the enamel making it softer and weaker.

ENAMEL WEAR AND DISEASE.

We already know that enamel is the hardest material in the human body so it might seem surprising that tooth decay and poor oral health affects almost everybody at some point in their life. If enamel is really so tough, why can it wear and decay so easily?

As hard as enamel is, it can still be weakened quickly if it is exposed to unfavorable conditions for extended periods of time.The substance that causes the most damage to teeth enamel is acid. Unfortunately, our teeth can be under a constant attack from acid without us realizing it. Enamel has no nerve endings and therefore even if it becomes badly decayed we would still not feel any pain until it collapses and exposes the dentin layer. Understanding the role of acid and where it comes from can help us avoid tooth decay, fillings, and tooth loss.

Acids can come into contact with the teeth from a number of sources but mostly they come from the following –

• Bacterial plaque: This is a sticky film that forms on the teeth each and every day. Plaque consists of about 70% bacteria, which, as part of their life cycle, they feed of the sugars and carbohydrates that we eat and then excrete organic acid onto the teeth as a byproduct. This acid then begins to dissolve away calcium and phosphate from the enamel surface making the teeth softer and weaker.
• Dietary acids: Many of the foods and beverages that we consume are acidic in nature and can cause the teeth to become soft and vulnerable to decay. Many of today’s popular foods and drinks like, sweets, cakes, energy drinks, soft drinks and fruit juices all have a detrimental effect on our teeth.
• Acid Reflux: Acid reflux occurs when gastric acid travels up the esophagus ending in the mouth. People who suffer from acid reflux are at a high risk of experiencing oral health problems simply because of the increased acidity levels of their mouths.

HOW TO KEEP YOUR TEETH ENAMEL HEALTHY.

Since acid is known to be the most damaging substance to teeth, it makes sense that in order to keep our teeth healthy and strong we need to limit our mouths exposure to acid. To keep acid attacks to a minimum follow these steps – 

• Brush teeth twice a day for two minutes: It is very important to remove the plaque that has built up throughout the day and night. Any plaque that is allowed to stay in contact with the teeth for extended periods of time will maintain the concentration of acid on the enamel surface. Plaque is soft and relatively easy to remove provided it is dealt with quickly. If plaque is allowed to sit on the teeth for more than 48 hours it will begin to harden and calcify to the point where calculus is formed. Unlike plaque, calculus can’t be removed by normal teeth cleaning and will need to removed by your dentist.
• Floss teeth every day: Since teeth bushing only cleans about 60% of the teeth surfaces, it is important to use dental floss or an interdental brush to clean the areas between the teeth that a toothbrush can’t reach.
• Use a therapeutic toothpaste: Fluoride toothpaste has a proven record of being effective at strengthening enamel and resisting decay. For people who find the use of fluoride to be too controversial, there are other toothpastes such as Theodent that use a chocolate extract to harden the enamel crystals
• Limit snacking: Eating sugary snacks or beverages often throughout the day can cause the mouth to become almost permanently acidic. It takes the oral cavity about 30 minutes to recover to normal after eating, so if we continue to snack, the mouth is not able to achieve balance. It is best to eat snacks in one sitting and not spread them out throughout the day.
• Drink plenty of water: Drinking water is a great way to keep the mouth clean and flush away any food debris from the teeth.
• Eat Xylitol: Although xylitol tastes like regular sugar it has some very different properties that can benefit your oral health. Oral bacteria can’t process and digest xylitol in the same way that it can with regular sugar. Xylitol effectively starves off bacteria and reduces the harmful effects of plaque.

DENTIN

Dentin forms the main bulk of each tooth and it is comprised of roughly 70% inorganic matter and 20% organic matter and 10% water. The dentin layer is situated directly underneath the enamel on the crown and the cementum on the root. Because dentin contains less mineral content than enamel it is not as hard and has more elastic properties. It is the flexibility of the dentin layer that prevents the enamel from becoming too brittle and fracturing. Inside the dentin, there are millions of microscopic tubes that diverge out from the pulp cavity to the enamel on the crown and the cementum on the root.

Facts about dentin.

Dentine is:

• Yellowish in color and is visible through the semi-translucent enamel.
• Not as hard as enamel but harder than bone tissue.
• Sensitive to external stimulation such as heat, cold and sweet substances.

DENTIN DECAY AND DISEASE.

The dentin layer is protected by enamel on the crown and cementum on the root. If this protection is compromised then the dentin is also susceptible to decay. Dentin will decay quicker than enamel because it is softer and more porous. Once the dentin is infected there will probably be some level of ongoing toothache to alert you that the tooth needs attention. It is important to schedule a visit to the dentist immediately because at this stage the tooth can still be fixed by a simple filling to close the hole in the enamel and seal off the dentin layer.

CEMENTUM

Cementum covers the root of each tooth as well as contributing to the supporting structure of the tooth. Cementum comprises of about 45% inorganic matter and 55% organic matter and is softer than both enamel and dentin.

Facts about cementum.

Cementum is:

• Similar in hardness to bone.
• Pale yellow in color.
• Responsible for helping to keep to tooth fixed in place.

PULP

The pulp is the organic, living part of the tooth that comprises of nerves, blood vessels, fibers and, cells. The pulp is situated inside the pulp cavity and root canal and underneath the dentin and enamel layers. The pulp cavity diminishes in size as we get older due to the gradual increase in secondary dentin.

Facts about pulp.

Pulp is:

• Very sensitive to external stimulation, which is manifested as pain.
• A sensory organ that will respond quickly if the dentin is exposed by initiating the formation of extra dentin (called reactionary dentin).
• Susceptible to irritation and inflammation if it is exposed.

PULP DISEASE AND DECAY.

If decay reaches the pulp cavity, the level of toothache will be intensified considerably. It is important to visit your dentist immediately so the level of infection can be accessed. In some instances, it may be possible to save the tooth with a simple filling but often the dead or dying pulp will need to be removed with a root canal treatment or the tooth may need to be extracted completely.