Anatomy Lesson: The Mouth

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by Chris Edwards, DDS


National Health Review

SMILE! The mouth – or oral cavity – is the gateway to health in the human body. Digestion starts here. Liquids and solids enter into and through the mouth. The teeth macerate solid food for proper absorption in the gut to refuel the 100 trillion cells of the body.

Proper functioning of the mouth is vitally important for overall health, communication and emotional release.

Mouth Make Up

The mouth is a system composed of hard tissue, soft tissue and bacteria.

Hard Tissue

The hard tissue consists of the teeth, the mandible (lower jaw bone) and the maxilla (upper jaw bone).
There are two sets of teeth in the human mouth. The primary or baby teeth are formed as tooth buds in the jaw while the baby forms in utero.

These 20 teeth start to break through the gums (called eruption) during the first year of life and adult teeth slowly replace them over the course of the next 12 years.

There are 32 adult teeth. They begin erupting at about age six and are usually completed at age 18 when the wisdom teeth push through.

The top part of each tooth, and the only visible part, is the crown. The enamel is the outermost layer of the crown and is the hardest substance in the body. Under the enamel is the dentin, the organic layer of the tooth. It is closest to the pulp, which is the soft tissue found in the center of all teeth. This is where the nerve tissue and blood vessels also are found.

The root is the part of the tooth that is anchored in the bone and makes up two-thirds of the tooth. The blood vessels and nerves follow a root canal from the tip of the root to the pulp. Misalignments, decay, trauma and wear cause the majority of problems in teeth. Proper care and maintenance can alleviate many problems.

Soft Tissue

The next part of the system is the soft tissue. The soft tissue is comprised of the lips, tongue, cheeks and gums. The gums attach to the teeth and protect the underlying jawbone. There are salivary glands imbedded in the soft tissue that release 64 fluid ounces of saliva per day, which keep your mouth moist and aid in digestion. The lips and tongue move food through your mouth and facilitate speech.

Most problems in the soft tissue of the oral cavity are lesions caused by injury, infection or cancer. The likelihood of problems can be lessened by good oral hygiene: brushing and flossing daily, visiting the dentist regularly and abstaining from smoking and chewing tobacco.


The human eye cannot see this final part of the system, although its evidence is visible in many mouths. There are over 400 known types of bacteria that can live in the mouth.

Good bacteria support the overall health of the system, while bad bacteria wreak havoc in the mouth causing dental decay, gum disease, bad breath and the majority of problems seen in dentistry.

Bacteria live and reproduce on the teeth and tongue. It takes 24 hours for bacteria to attach to a tooth and develop a biofilm, a sticky layer more commonly known as plaque. Plaque is a fertile breeding ground for bacteria and the start of trouble.

The bad boy of bacteria is Streptococcus Mutans, also known as the primary producer of plaque. These bacteria love carbohydrates and sugar and as they eat the foods we eat, they produce acid as a by-product. This acid causes the demineralization of enamel, which makes it porous enough for the bacteria to reach and feast on the dentin, a process called Dental Caries. As the infection progresses, the enamel caves in and creates a hole called a “cavity.” Fortunately, this bacterial disease is preventable.

Caries on the chewing surfaces of the teeth are usually in the pits and fissures of the enamel that were incompletely formed when the teeth came through. A toothbrush does not reach far enough in to clean this area, and the space becomes a prime target for cavities. Micro-dentistry, which includes sealants and preventive resins, can help remedy this problem.

While plaque is creating caries on the tooth surfaces, the gums also are affected. The immune system responds to the bacteria with inflammation in the gum causing swelling, redness and bleeding. The bacteria also colonize on the root under the gum. The immune system is not able to engulf and destroy these bacteria as they are separated from the body’s defense system by the epithelium, a thin protective layer of tissue covering the gums. Although the bacteria are inside the mouth, they are effectively outside the body.

This infected area, known as a periodontal pocket, causes a low-grade infection that can lead to the destruction of the jawbone surrounding the teeth. Left untreated, this chronic infection grows and more pathologic bacteria take up residence and colonize on the sides of the roots, causing acute infection and tooth loss.

Overall Health Link

Current research has demonstrated a solid connection between overall health and the health of the oral cavity. Ongoing research is still working to uncover the exact links of why patients with inflammation and periodontal disease are at much higher risk of heart attack, stroke, diabetic and pregnancy complications, among other conditions.

Good oral health can help prolong dental health as well as overall health. The daily removal of plaque that attaches to the tooth, both above and below the gum, is the cornerstone of good oral health.

There are many tools available to aid in plaque control, but brushing and flossing still are considered the easiest and best. Removal of tartar and toxins from the roots of the tooth by a dental hygienist (teeth cleaning) is also important, along with regular x-rays and exams by a dentist.


Dr. Edwards graduated from the United States Merchant Marine Academy and Temple University School of Dentistry. He completed a general practice residency at the Queens Medical Center in Honolulu. To reach Dr. Edwards you may call 321-751-7775 or visit