Just about everybody knows that brushing, flossing, and regular dental checkups are crucial for keeping teeth healthy, but knowing isn’t always doing. It’s estimated that only two-thirds of Americans brush twice a day, and far fewer floss daily, though many won’t admit it, even to their dentists. Only half see a dentist twice a year, and about one-third don’t go even once a year, often because they can't afford it; most Americans have no dental insurance or only limited coverage, and nearly 50 million live in areas where few dentists practice. Thus cavities and periodontal disease remain huge—but preventable—problems.
Cavities: not just for kids
A cavity is the breakdown of a tooth from acid produced by bacteria in the mouth. Caries, from the Latin word for rotten, is the scientific name for cavities. Teeth surviving from early humans and pre-humans show that dental caries have always been with us, though they were relatively rare, largely because prehistoric diets contained little or none of the refined carbohydrates that oral bacteria feed on. Dental decay and the resulting “toothaches” have been written about or depicted since ancient times.
For millennia, the “holes” in teeth were blamed on “tooth worms” that supposedly burrowed into them, and they were filled in with everything from beeswax to tin. It wasn’t until the 18th century that scientists gradually began to understand the process of dental decay and not until the 1890s that they figured out that acid-forming bacteria were the culprits. According to the CDC, at least 27 percent of adults ages 20 to 44 have untreated caries.
Your mouth contains more than 700 species of bacteria, but only a small minority of them (notably Streptococcus mutans and certain Lactobacillus species) are “cariogenic”— that is, can produce the high levels of acid that can cause cavities.
Under healthy circumstances, the normal balance of oral bacteria does not harm teeth. But when this balance is disrupted by factors such as reduced saliva production, a poor diet, and inadequate oral hygiene, cariogenic bacteria flourish and collect around the teeth and gums in a sticky, cream-colored film called plaque (see "Glossary of Dental Terms," below). These bacteria feed on dietary sugars and certain other carbohydrates in the mouth, producing acids that lower the pH of the saliva and cause the calcium and phosphorus in tooth enamel to start dissolving, a process called demineralization. Like bones, teeth are hard because they are mineralized. Demineralization erodes the tooth from the outside in, and if the process is not halted, the interior of the tooth becomes susceptible to bacterial invasion.
Glossary of Dental Terms
Brush up on your oral-health lingo with these definitions of commonly used terms.
The early stage of caries formation, visible as tiny white spots on the teeth, can be halted and even reversed by increased production of saliva, which brings minerals that tooth enamel can absorb, and by fluoride (in toothpaste, water, or dental treatment), which aids in remineralization. However, if demineralization progresses, the damage goes deeper into the enamel and the underlying dentin, resulting in a cave-like hole in the tooth (hence the name “cavity”). This process usually takes months or even years.
Some sites, like molars or areas between teeth, are more prone to plaque formation because of reduced saliva flow around them and because of grooves that can retain plaque bacteria—and simply because they are harder to clean. Plaque also tends to collect at the gum line.
When left untreated, dental caries can gradually destroy the tooth, leading to pain and spreading infection. If the bacteria enter the tooth’s pulp (the innermost part, containing blood vessels and nerves), the infection can cause pus to form as part of the immune response to the infection. This usually necessitates a root canal procedure—in which the infected pulp is removed and the inside of the tooth cleaned and sealed and then usually topped with a crown—or, if the tooth can’t be saved, extraction. If the abscess is not treated, the infection can spread into the jawbone, the blood, and other body parts, including the brain.
Many factors increase the risk of dental caries, notably diet (a lot of sugar and other refined carbs, for example), poor oral hygiene, and dry mouth syndrome, as well as the susceptibility of a tooth’s surface to decay.
About half of Americans over age 30, including 70 percent of those over 65, have some form of periodontal (gum) disease, according to the CDC, but many if not most don’t know it. The culprits are an estimated 10 to 20 strains of bacteria in the mouth, along with poor dental hygiene. When these bacteria build up in plaque (which then hardens into tartar), they cause chronic inflammation of the gums; this is called gingivitis and is characterized by redness and swelling, as well as bleeding during brushing and flossing. Gingivitis is a mild form of gum disease that can usually be reversed with daily brushing and flossing and professional dental cleanings.
Left untreated, however, gingivitis can advance to periodontitis, in which the gums are damaged and detach from the teeth and form pockets that become infected with bacteria. Bacterial toxins, along with enzymes released as part of the body’s natural response to the infection, further irritate and inflame the gums. The immune system increases its inflammatory response to the bacteria as plaque and tartar spread below the gum line. In advanced stages, gums, bones, and other tissues that support the teeth are gradually destroyed; teeth may eventually become loose and have to be removed. Largely as a result of periodontal disease, about one in four Americans over age 75 have lost all their natural teeth.
If you don’t brush and floss regularly, you’re likely to develop gum disease. But its progression depends on many factors besides your oral hygiene, including genetics and how well your immune system responds. Brushing alone can’t remove bacteria in tartar, in pockets, or below the gum line—this is where flossing and professional cleanings are crucial. Often a deep-cleaning method called “scaling and root planing” is necessary, in which tartar is scraped off at and below the gum line.
Basics of Dental Care
Brushing your teeth isn't rocket science, but most people fall short in their technique or have gotten sloppy over the years. Here's a refresher, plus tips for flossing.
Besides poor oral hygiene, a major risk factor for periodontal disease is tobacco, since chemicals in the smoke (or liquid from chewing tobacco) harm the gums and teeth. A poor diet is also a factor, especially one high in sugars or sticky carbohydrates (as in dried fruit or caramel). Certain medications and oral contraceptives increase susceptibility to gum disease. Hormonal changes can also adversely affect your gums. Thus, during puberty, pregnancy, menstruation, and menopause, women may find themselves more prone to gingivitis. Because saliva helps wash away foods as well as bacterial toxins, anything that decreases saliva production (such as certain drugs or breathing through your mouth) can make gum disease worse. Diabetes and other chronic diseases that lower resistance to infection can also play a role; chronically ill people need to be particularly careful about dental care.
Treatment for periodontal disease depends on the stage of the disease. You may need a prescription mouth rinse, oral irrigation with an antibiotic solution, general antibiotic treatments, more thorough removal of tartar below the gum line, or surgery. Your regular dentist will probably refer you to a periodontist. A wide range of treatments are now available.
The gums-heart connection?
In recent years observational studies have consistently found that people who have periodontal disease are at increased risk for cardiovascular disease (CVD) and its progression. This has led some researchers and dentists to suggest that gum disease and the bacteria that cause it can contribute to CVD—and that good oral hygiene and treatment of gum disease can help protect the heart and arteries.
Research has also linked gum disease to other chronic, systemic disorders, notably diabetes, as well as respiratory and kidney disease and even certain cancers, but these links are more tenuous. And deterioration of oral health often accompanies a more general age-related decline in health.
In 2012 the American Heart Association reviewed hundreds of studies and, in a Scientific Statement, concluded that so far there’s no conclusive evidence that gum disease contributes directly to CVD. The American Dental Association concurred. As with so many findings from observational studies, association or correlation doesn’t equal causation.
Still, the idea that dental disease can play a role in systemic disorders like CVD is biologically plausible. For one thing, oral bacteria can enter the bloodstream and affect the heart and arteries. And the inflammation involved in gum disease could conceivably trigger the inflammation that plays an important role in atherosclerosis (and other chronic diseases).
Periodontal and cardiovascular diseases are both complex, multifactorial disorders that develop over time, making it hard to untangle any direct “what comes first” connections. Moreover, diseases of the mouth and cardiovascular system share many risk factors, notably smoking and diabetes, and that may help explain why they often occur in the same people. Thus the conditions may both occur because of the same underlying factors, rather than one causing the other. Even so, when researchers adjust the data to control for these shared factors, the link seen in studies usually persists, suggesting that gum disease plays an independent role in the development of CVD.
A systematic review of 25 clinical trials, published in the Journal of Clinical Periodontology, found that treatment for periodontitis was associated with improvements in many CVD-related factors, notably blood cholesterol, several key inflammatory markers, and arterial function, especially in people who already had CVD or diabetes. The Dutch authors concluded that doctors should make sure that patients with CVD are screened and treated for periodontal disease “to improve their cardiovascular risk profile and thereby reduce the risk for future occurrence of CVD events.” They also advised that dentists should discuss CVD risk factors, like smoking and being overweight, with their patients.
Well-designed clinical trials are needed to determine whether treating periodontal disease can actually reduce the risk of heart attacks, strokes, and other disorders (there would be ethical problems, however, with randomized trials in which some people are chosen to have no periodontal treatment for a few years). Meanwhile, until all the answers are in, there are plenty of reasons to maintain good oral health and treat periodontal disease if it develops, regardless of the effect on systemic inflammation in the body and the risk of cardiovascular and other chronic diseases.
Published February 03, 2016