Everyone appreciates the esthetics of a perfect smile, many understand the importance of a healthy mouth, but few actually know how a tooth is really made. For this reason, let us speak about structure, shape and anatomy of teeth.
Every tooth presents a particular structure and shape according to its function, and is made of various tissues of different degrees of hardness and resistance, from the outside inwards.
CROWN: it’s the visible part of the tooth, the strongest and more resistant. Its shape varies according to type and function: incisors have wide ridges and marked angles to cut food, canines are sharply pointed to tear and rip, premolars and molars have a rugged and rounded shape with sulcus and cuspids to grind and mince.
The outer part of a crown is made of tooth enamel, the hardest tissue of human body, composed for more than 95% of minerals. Thanks to its resistance, enamel is functional when mincing and chewing, as well as for protecting the inner tissues of the tooth from acids and bacteria. Enamel does not present nerve endings or blood vessels; this is the reason for which tooth decay, initially, shows no symptoms and causes no pain. Despite its hardness, enamel is nonetheless affected by physiologic wear in time, that can be caused by chemical erosion (due to the acidness of food or acid reflux) or mechanical wear (bruxism, malocclusion, improper brushing, etc.).
Dentin, the underlying layer, can be made more visible as enamel gets thinner. It is a yellowish substance mainly made of inorganic material, as well as of water and organic material filling the internal portion of the crown and the roots. Dentin is crossed by tubules, canals containing the extension of special cells (odontoblasts), and that are responsible for tooth sensitivity. For this reason, in cases of worn enamel and exposed dentin, the patient can be more susceptible to heat, cold and sweet food.
The effects of tooth erosion are often not very visible at the beginning, and may show only in an advanced phase of the process. It is therefore fundamental to have correct eating habits, as well as to regularly attend the oral hygienes appointments which can lead to the early detection of any tooth pathology.
The tooth core is composed of tooth pulp, a soft “live” tissue, not-calcified and rich in nerve endings and blood vessels, through which adequate amounts of blood, oxygen and nutrients are provided to the teeth.
Protected by enamel and dentin, tooth pulp is located in a cavity starting from within the crown (pulp chamber), reaching the inner part of the root canal.
As well as tooth nourishing, tooth pulp is responsible for the production of dentin.
If, in case of tooth decay or trauma, pulp is contaminated by bacteria, an inflammation could occur, causing pain in the patient, which could evolve in an infection and lead to the devitalization of the tooth (painless removal of the infected tooth pulp, cleaning of root canals and filling with specific materials).
In some cases, the infected tooth could be affected by spontaneous necrosis, and failure to remove the contaminated tooth pulp may cause the formation of a granuloma (chronic inflammation of the tooth root apex) or a dental abscess (painful purulent swelling).
NECK: it’s the area between the crown and the root, where the gingiva margin is located. By adhering to the bone, the main function of the gingiva is to protect the neck and the deeply covered periodontal structures (ex. bone) from the bacteria forming plaque and tartar.
This is a particularly delicate area due to the tendency of bacteria plaque to accumulate, leading to possible inflammation, gum retraction and tooth decay, that can be favored also by improper or aggressive brushing.
ROOT: it’s the part of the tooth that can not be seen, located under the alveolus (the bone cavity containing the tooth), to which the tooth is anchored by the periodontal ligament, the fibrous tissue structure connecting the root cement (a hard and thin external root coating, similar to bone) to the alveolar bone. Teeth don’t all have the same number of roots: incisors and canines have only one root, just as premolars (though upper premolars may have two). Upper molars have three roots, while lower ones have two.
Despite the common belief, even milk teeth have roots. As the moment of their replacement approaches, the milk teeth root apex starts wearing away and gets re-absorbed thanks to the push supplied by the permanent teeth below: it is for this reason that deciduous teeth start wobbling and eventually fall.
At the end of the root is the apical foramen, which connects tooth pulp to nerves and blood vessels.
Each tooth has a complex structure: it is therefore essential to take care of the personal oral health with regular dental hygiene sessions and check-ups in order to prevent risks and pathologies which may affect various part of the teeth.