Elephants displace teeth from the back; they’re grinders. But most animals are like us and have a single series of adult teeth, since we need to develop perfect occlusion and would lose this with continual change. Crocodiles have “nails” for teeth, which are designed for grabbing rather than chewing. Our mandibles were fused about 40 million years ago. We lost the independence of selective chewing but gained the ability to spread the force of chewing to the entire jaw. We also have a two-post jaw joint, which allows our mandible to slide forward and then drop down. This enables the masseter muscle to develop increased force during chewing. Carnivores don’t have the mechanism since they must grab and tear their food.
Your jawbone (docs call it the mandible): The only time we ever get to see jaws is in museums, and they’re usually of the shark or dinosaur variety. But the human jaw is a powerful little clamp of its own—exerting 50 to 250 pounds per square inch of pressure during chewing. It’s also extremely efficient: It’s the only joint in the body that purposely dislocates itself during a motion, using two points of attachment—one lever point in the back of the jaw and another two inches in front. Every time you chew, your jaw dislocates and relocates, allowing you to crush food so you can swallow and digest. But the muscles that move the jaw can also be a source of pain. If you chew too much or subconsciously clench your jaw during stressful times, your jaw muscles can spasm. Stress-induced clenching or grinding can cause slight misalignment of the jaw, leading to jaw, neck, or eye pain, as well as jackhammer-like headaches. By the way, if you lose your teeth—be it through decay or an errant baseball—your jawbone will eventually erode away as well (use it or lose it). The main purpose of your jawbone is to support teeth, and a very intricate and complicated set of muscles, ligaments, and skin holds your jaw in place.
Your gums: We all know how well that peas-in-the-teeth look impresses first dates and job interviewers, and it doesn’t go over too well with the rest of your body either. Lest you think your gums aren’t important: The amount of tissue involved in a severe gum disease case is approximately the same as the surface of the skin on the back of the hand. What would you do if the back of your hand was bloodred and swollen and bled at the slightest touch? You would haul your buns to the doctor. But when the same thing happens in the mouth, you think it’s normal. When plaque—that sticky gunk made up of bacteria, saliva, and yesterday’s dinner—wedges between your teeth into your gums, it triggers a process of inflammation that leads to periodontal disease (gingivitis is infection of the gums, while periodontitis occurs when the disease progresses to the ligaments and bones around the teeth). Regular flossing and checkups can rid you of plaque and help save your teeth. Gum disease is linked to many other problems, likely because the same bacteria that can cause periodontal disease can also trigger an immune response that causes inflammation and hardening of the arteries. That plaque that’s found near your teeth contains a zoo of bacteria and proteins, sugars, and fat, as well as calcium and phosphorus. This tough stuff sticks to your teeth and causes gingivitis (gingivitis is an even better indicator of heart disease than levels of cholesterol).
Your teeth. Wiggle your jaw around (go ahead, nobody’s looking). Your top teeth are fixed to your skull, while your lower jaw has the flexibility to move front to back and side to side. If the top and bottom are misaligned, your upper teeth can’t adjust, so you end up wearing down your teeth. How do you know if you’re a teeth grinder? One, by taking the flat-teeth test in Chapter 3, and two, because teeth grinders show less tooth when they smile, which makes them look older and less attractive.
While acceptable on dance floors, grinding isn’t so great for your mouth. It causes premature aging as the wearing down of the front teeth inhibits the ability of the jaw to work efficiently, causing back teeth to wear down as well. Grinding can also injure your jawbone joint, called the TMJ (temporomandibular joint). If you’re a grinder (which can be caused by stress or misalignment), you’ll want early detection so your bite can be analyzed and you can be fitted for a night-guard mouthpiece that prevents you from grinding while you sleep. Left untreated, your teeth will eventually break and split from your gums. It depends on the break or the severity of the split if they can be saved or not. If it’s not too severe, crowns can cover them. Severely worn teeth may have to be replaced (and that can cost up to $2,000 per tooth).
Figure 3.2 Taste Test Much of our perceived beauty comes from deep inside our voice portal: The way our teeth look (not to mention the way our breath smells) influences our relationships with others. Proper flossing, tongue scraping, and other methods of oral hygiene are little things you can do that have major results. Grinding your teeth will flatten them and can cause one heck of a headache. As we age, we make less saliva from our mouth glands, which besides causing us to made weird noises with our tongues can lead to tooth decay.
FACTOID
You may sleep next to a person who snoozes with a mouth that’s open wide enough for a subway to get through. The reason why it’s a problem? It’s like driving a car without the windshield. When mouth breathers (sleeping or not) are exposed to all that air (caused by a clogged nose), it dries the gum and enamel to create gingivitis and possible bone decay.
FACTOID
You’re naturally susceptible to tooth decay if your mother was unhealthy during pregnancy or you had poor childhood health, perhaps because the foundations of the teeth were not created well. Today, major food sources that cause decay include carbonated drinks that dissolve enamel and sugary gums and mints, since these continually bathe our teeth with food bacteria love. Also, avoid sticky foods and candies (such as raisins, unless you religiously brush afterward), which can stick to your teeth (sucking candies are better for the health of your teeth).
FACTOID
Your sinus region generates a liter of fluid daily, so you’re continually washing boogers down your throat. There’s nothing wrong with picking your nose if you keep the area moist (and use a tissue paper on your fingertip). You can also use a neti pot daily to clean the sinuses (it’s like brushing your teeth for your sinuses).
FACTOID
White spots on teeth are usually a sign of enamel breakdown, decalcification, and too much fluoride. The problem isn’t only that we get too much fluoride from our drinking water but that every year more than 20,000 young kids (especially those under six) swallow their toothpaste, meaning they get lots and lots of fluoride, which can lead to the discoloring or worse. A lethal dose of fluoride is only 500 mg for small children—that’s not too hard to get if a big glob is put on a toothbrush. If your kid does eat toothpaste, have him drink a lot of milk—that neutralizes the fluoride—and head over to the emergency room. Keep the toothpaste to a pea size for children, to lower the amount they might swallow. Kids and pregnant mothers can also discolor developing teeth by taking tetracycline, so choose different antibiotics to prevent speckled teeth.
YOU Tips!
It’s one of the most common dreams around: losing your teeth by the bucketful. We’re not dream psychologists, so it’s not our place to suggest that such dreams are symbolic of your chaotic life (though some people believe that these dreams indicate that you’re a grinder). But we do want to help you avoid the nightmare of your teeth falling out in real life. Of course, you know the basics—you gotta brush, you gotta floss, you gotta see a dentist and dental professionals, you gotta avoid barroom brawls. But here are some more details that’ll ensure that your new nickname becomes Mighty Mouth.
TAKE TWO. Waiting in traffic, two minutes seems like an eternity. Playing in bed, two minutes feels like a flash. At the sink, two minutes is the time you need to spend brushing your teeth in order to clean them adequately and reduce plaque. Use a soft brush and rub the bristles up toward the gums, so you can get to the actual cusps and gum. Change your toothbrush every two months. Those newfangled ultrasonic brushes amaze many dentists with their plaque-fighting abilities (and some have two-minute timers built in). Many cultures, by the way, believe that massaging your gums with your fingers is helpful in preventing periodontal disease. We actually