Diseases of the Oral Cavity
Tooth decay, known formally as dental caries, has been a serious health problem for all nations since time immemorial. For centuries, tooth decay was thought to be the handiwork of an elusive and, in some cultures, evil tooth worm that gnawed holes into the white, highly mineralized enamel and left all those in its wake in pain. But superstition has yielded to science and its explanation that certain oral bacteria discharge mineral-eroding acid onto the enamel, starting the gradual process of decay. Over the last several decades, dental researchers have made tremendous progress in defining and learning to thwart the decay process. This work has involved the three-pronged strategy of discovery, innovation, and prevention - and produced one of the major public health success stories of the 20th century.
Few people were spared the ordeal of losing teeth, often early in life. The combination of tooth decay and periodontal diseases left 17 million people age 45 and older — about three out of 10 Americans — with none of their natural teeth. In fact, the most common cause of WWII draft rejection was too few teeth because of tooth decay. Until the 1970s, the cause of tooth decay continued to be a subject of debate, with some believing dietary deficiencies were the culprit and others focusing on oral bacteria. This uncertainty made effective prevention strategies difficult, if not impossible, to create. Moreover, brushing one's teeth each day was a fairly recent hygienic step forward in dental care, reportedly popularized by returning soldiers from World War II.
The NIH completed the first water fluoridation study that established the benefits of fluoride in fighting tooth decay. Several years would pass before fluoride, the mainstay of modern prevention strategies, would become a common ingredient in water, toothpaste, and other products.
Tooth decay was considered an irreversible disease process — once a cavity started, the only remedy was to drill out the decay and fill the tooth with a restorative material.
Tooth decay is no longer the national epidemic it was a few generations ago. Millions of American children now have little or no decay, and total tooth loss or edentulism is now much less common. Without research progress in the fight against dental caries and periodontal diseases, there would be an additional 18.6 million Americans age 45 and older with none of their natural teeth.
Prevention is now the mantra in American dentistry. In addition to improved products to fight tooth decay, more people benefit from preventive dentistry, including the use of fluorides and dental sealants to prevent decay. Compared to previous years, these techniques have made it possible for millions more people to keep their natural teeth for a lifetime. It is estimated that from 1979 through 1989 alone, the American public saved more than $39 billion in dental expenditures due to the power of prevention. Since the 1950s, the total federal investment in NIH-funded oral health research has saved the American public at least $3 for every $1 invested.
New technologies will further prevent tooth decay. Research is underway to develop powerful imaging tools that can detect the earliest demineralization of tooth enamel. These tools will allow the application of special solutions to remineralize the tooth and reverse early decay.
Examples of NIH research projects funded in 2010 include "Development of high performance, caries-inhibiting dental nano-materials" and "Enamel mineral formation during murine odontogenesis."
Advances in DNA sequencing produced vast gene databases for many of the bacteria that cause tooth decay. These bacterial blueprints now allow scientists to identify specific genes essential to the decay process, and it may be possible in the future to directly target these genes and inactivate the ability of these bacteria to cause decay.
The bacteria that cause tooth decay live in complex communities called biofilms. Great strides have been made in learning how the bacteria communicate with one another within this biofilm. By jamming the communication signals among the bacteria, it may be possible one day to disrupt the biofilm and end the threat of tooth decay.
Periodontal (Gum) Disease
There are many different varieties of periodontal disease, and many ways in which these variations manifest themselves. All require immediate treatment by a periodontist to halt the progression and save the gum tissue and bone. Here are some of the most common types of periodontal disease along with the treatments typically performed to correct them:
Gingivitis is the mildest and most common form of periodontitis. It is caused by the toxins in plaque and leads to periodontal disease. People at increased risk of developing gingivitis include pregnant women, women taking birth control pills, people with uncontrolled diabetes, steroid users and people who control seizures and blood pressure using medication.
Chronic Periodontal Disease
Chronic periodontal disease is the most common form of the disease, and occurs much more frequently in people over 45. Chronic periodontal disease is characterized by inflammation below the gum line and the progressive destruction of the gingival and bone tissue. It may appear that the teeth are gradually growing in length, but in actuality the gums are gradually recessing.
Aggressive Periodontal Disease
Aggressive periodontal disease is characterized by the rapid loss of gum attachment, the rapid loss of bone tissue and familial aggregation. The disease itself is essentially the same as chronic periodontitis but the progression is much faster. Smokers and those with a family history of this disease are at an increased risk of developing aggressive periodontitis.
Periodontal Disease Relating to Systemic Conditions
Periodontal disease can be a symptom of a disease or condition affecting the rest of the body. Depending on the underlying condition, the disease can behave like aggressive periodontal disease, working quickly to destroy tissue. Heart disease, diabetes and respiratory disease are the most common cofactors, though there are many others. Even in cases where little plaque coats the teeth, many medical conditions intensify and accelerate the progression of periodontal disease.
Necrotizing Periodontal Disease
This form of the disease rapidly worsens and is more prevalent among people who suffer from HIV, immunosuppression, malnutrition, chronic stress or choose to smoke. Tissue death (necrosis) frequently affects the periodontal ligament, gingival tissues and alveolar bone.
Oral CancerAbout Oral Cancer
Oral cancer includes cancers of the mouth and the pharynx (the back of the throat). Oral cancer accounts for roughly two percent of all cancers diagnosed annually in the United States. Approximately 35,000 people will be diagnosed with oral cancer each year and about 7,600 will die from the disease. On average, 60 percent of those with the disease will survive more than 5 years. Oral cancer most often occurs in people over the age of 40 and affects more than twice as many men as women.
What Puts Someone at Risk?
Tobacco and alcohol use. Most cases of oral cancer are linked to cigarette smoking, heavy alcohol use, or the use of both tobacco and alcohol together. Using tobacco plus alcohol poses a much greater risk than using either substance alone.
HPV Infection with the sexually transmitted human papillomavirus (specifically the HPV 16 type) has been linked to a subset of oral cancers.
Age. Risk increases with age. Oral cancer most often occurs in people over the age of 40.
Sun Exposure. Cancer of the lip can be caused by sun exposure.
Diet. A diet low in fruits and vegetables may play a role in oral cancer development.
Possible Signs & Symptoms
See a dentist or physician if any of the following symptoms lasts for more than 2 weeks.
- A sore, irritation, lump or thick patch in your mouth, lip, or throat
- A white or red patch in your mouth
- A feeling that something is caught in your throat
- Difficulty chewing or swallowing
- Difficulty moving your jaw or tongue
- Numbness in your tongue or other areas of your mouth
- Swelling of your jaw that causes dentures to fit poorly or become uncomfortable
- Pain in one ear without hearing loss
It is important to find oral cancer as early as possible when it can be treated more successfully. An oral cancer examination can detect early signs of cancer. The exam is painless and takes only a few minutes. Your regular dental check-up is an excellent opportunity to have the exam. During the exam, your dentist or dental hygienist will check your face, neck, lips, and entire mouth for signs of cancer.
Among the most common, irritating and difficult to diagnose problems with head and neck pain are temporal mandibular joint problems, more commonly known as TMJ problems. The joint is located near the ear where the top of the mandible or lower jaw meets the upper jaw at the base of the skull.
Like all other joints in the body, the TMJ is subject to inflammation and other chronic joint problems. Many of these issues may be caused by destructive bite habits like clenching or grinding. These actions cause pressure on the joint that can lead to inflammation and general breakdown of the joint itself. What makes TMJ problems difficult to diagnose and treat properly is the fact that the symptoms vary widely in both location and severity. Symptoms can range from a slight clicking in the jaw with no pain to severe head and neck pain which is not relieved by medication.
Once diagnosed properly treatments include everything from simple placement of a nightguard, which prevents pressure on the joint to surgical intervention in more severe cases. A dental health professional is the person most able to diagnose this widely variable and very common issue.
Malocclusion means the teeth are not aligned properly.
Occlusion refers to the alignment of teeth and the way that the upper and lower teeth fit together (bite). Ideally, all upper teeth fit slightly over the lower teeth. The points of the molars fit the grooves of the opposite molar.
The upper teeth keep the cheeks and lips from being bitten and the lower teeth protect the tongue.
Malocclusion is most often hereditary, which means the condition is passed down through families. There may be a difference between the size of the upper and lower jaws or between jaw and tooth size, resulting in overcrowding of teeth or in abnormal bite patterns.
Variations in size or structure of either jaw may affect its shape, as can birth defects such as cleft lip and palate. Other causes of malocclusion include:
- Childhood habits such as thumb sucking, tongue thrusting, pacifier use beyond age 3, and prolonged use of a bottle
- Extra teeth, lost teeth, impacted teeth, or abnormally shaped teeth
- Ill-fitting dental fillings, crowns, appliances, retainers, or braces
- Misalignment of jaw fractures after a severe injury
- Tumors of the mouth and jaw
There are different categories of malocclusion.
- Class 1 malocclusion is the most common. The bite is normal, but the upper teeth slightly overlap the lower teeth.
- Class 2 malocclusion, called retrognathism or overbite, occurs when the upper jaw and teeth severely overlap the bottom jaw and teeth.
- Class 3 malocclusion, called prognathism or underbite, occurs when the lower jaw protrudes or juts forward, causing the lower jaw and teeth to overlap the upper jaw and teeth
- Abnormal alignment of teeth
- Abnormal appearance of the face
- Difficulty or discomfort when biting or chewing
- Speech difficulties (rare) including lisp
- Mouth breathing (breathing through the mouth without closing the lips)
Exams and Tests
Most problems with teeth alignment are discovered by a dentist during a routine exam. The dentist may pull your cheek outward and ask you to bite down to check how well your back teeth come together. If there is any problem, the dentist will usually refer you to an orthodontist for diagnosis and treatment. Dental x-rays, head or skull x-rays or facial x-rays may be required. Plaster or plastic molds of the teeth are often needed.