Smile. Normally, we think of muscles as giving us the power to push, to pull, to heave, and to haul. But of the seven zillion cool things about the human body, here’s one of our favorites: The ever-so-subtle muscles in your mouth (and how you use them) determine exactly how you communicate with the world (see Figure 3.1). To do so, your mouth is controlled by a dozen or so muscles that all connect with the circular muscle around your mouth. Amazed that you have that many? That’s just a fraction of those around your eyes. Some pucker the lips, some suck in the cheeks, others lift or lower the lips. Just fire a few neurons that instruct your mouth to move a certain way, and depending on which direction those muscles pull, you can convey rage, sadness, happiness, sarcasm, excitement, fear, arousal, confidence, and on and on and on. Even smiles can be categorized by their beauty. The prettier the teeth, the more a person smiles. And the more a person expresses emotion by using the muscles of the face (especially around the eyes and mouth), the younger she looks.
FACTOID
Our wisdom teeth were nature’s version of a backup system—giving us one last set of teeth that would come out by the age we would’ve destroyed our molars when we lived in the wild. Why are they called wisdom teeth? Hopefully, we would get them at the age when we were wise enough to take care of them properly, usually by our mid teens. But unlike for your relatives 10,000 years ago, hopefully your molars haven’t fallen out yet. Because of this, crowding often occurs when wisdom teeth erupt, causing them to come in sideways. Cockeyed teeth can’t be cleaned and will destroy adjacent teeth—which is why they’re often removed.
Sore Sport
Surely, there are plenty of places on your body where you love a little tingling, but not right above your lip before a first date, an interview, or your reality show tryout. What starts as a tingle and ends as a full-blown cold sore can be as painful as it is embarrassing. The leading cause: herpes infections, which are transmitted through saliva, kissing, or sharing other people’s cups. This is called type 1, not to be confused with the genital variety, called type 2. The best treatment is a short course of virus-killing drugs like acyclovir (Zovirax) or valacyclovir (Valtrex) combined with hydrocortisone cream. By the way, these infections aren’t just painful or embarrassing; they seem to relate to an increase in cancers of the mouth. If you know the sore is on its way, you’d do better to start the drug sooner, to try to shorten the nearly two weeks of suffering (they can come back when you have a cold, which is why they’re called cold sores). An over-the-counter drug called Abreva seems to superpower your cells to resist this type of herpes infection. Give it a try if you don’t have the prescription stuff, and eat a soft, bland diet while you have the sores. If you figure that out on your own, your family won’t have to scrape you off the ceiling if you eat pickles.
The other type of mouth sore happens on the inside; they’re called aphthous ulcers (otherwise known as canker sores). People with iron, folate, and vitamin B12 deficiencies are more likely to get these sores, and sodium lauryl sulfate (SLS) in toothpaste triggers them. It takes about ten days for these to go away, but hydrocortisone ointment and keeping the sores clean with antibacterial mouthwash can reduce the duration.
Safari Secrets:
Lessons from the animal kingdom
Elephants replace their teeth five times and then they die. Great white sharks? They spit out new teeth as if they’re on a conveyor belt. Both are signs that the animal kingdom knows the true value of our munchers. Without them, you can’t survive.
FACTOID
Mercury fillings may not have gotten more bad press than conniving government officials, but they certainly have taken their own share of hits. The fact is that there’s nothing that shows that mercury in fillings causes any neurological damage, but there are better alternatives than having a mine in your mouth. (Note, however, that if you’re pregnant or nursing or plan to be, you should avoid any new mercury fillings because potentially damaging toxins can be released during the procedure that are toxic to incubating infants.) Fillings made of composite resin or ceramic are aesthetically more pleasing and may last longer. Also, there’s no need to have a silver filling removed and replaced unless there’s leaking, there’s decay under the filling, or it has a rough surface that keeps you from being able to floss.
Figure 3.1 Lip Trick Dozens of muscles around your mouth send messages about your thoughts and feelings—without your ever having to utter a word. The subtle cues you communicate through facial expression reveal the secrets you may be thinking.
These are the three classic types of smile:
The Mona Lisa (two-thirds of people): The corners of the mouth are pulled up and out, and the upper lip raises to show the upper teeth. The most attractive show all of their top teeth and about 2 millimeters of gums (any more and the smile is classified as “gummy”). Mona Lisa is considered most attractive, with the upper and lower lips moving out half an inch and up at a 40-degree angle.
The Canine (one-third of people): Here a particular muscle (called the levator labii superioris, for you anatomy junkies) is dominant and exposes the canine teeth before the full smile.
The Full Denture (rare): Here all of the upper and lower lips are working overtime to expose the whole dang shebang of teeth.
FACTOID
It’s a miracle that we don’t have more infections in such a dirty place as the mouth, but we actually need germs here to begin digestion. These germs keep fungus in check, as well as supply us with our own type of venom, since the human bite injects more bacteria into our enemies than any other species. But did you know that vegetarians really do have cleaner mouths than carnivores? It’s the rotting bits of meat between the teeth that feed mouth bacteria. As clean as a hound’s tooth? We think not.
As you age, you can work to change your smile with facial exercises and by taking care of your teeth. That’s important: Your teeth get worn down naturally as you age, and at the same the soft tissue around the mouth descends, leaving you with a Richard Nixon smile—showing all lower teeth and no upper. Teeth are going to move until they touch something that will make them stop. That might be a tongue, dental appliance, or other teeth. As teeth wear down and get shorter, this changes the normal tooth-to-gum ratio and gives the “gummy smile.”
Tongue: Besides being your taster, your tongue also helps you swallow and protects you from swallowing poison; you can thank your taste buds for that. Controlled by eight muscles and four nerves, your tongue helps move food and liquids down your esophagus. Of course, few people* think of the tongue as an organ of beauty; normal tongues are moist and pink and have bigger bumps toward the back. It’s when you develop problems that things can get a little hairy. Black hairy tongue, for example, occurs when taste buds elongate and change color (due to smoking or antibiotics). Your tongue can also develop cysts, ulcers, herpes infections, and yeast infections (which are called thrush; milk of magnesia or nystatin can chase the yeast right out of your mouth).
The Tooth About Health
Besides being the tunnel that food and flies enter, your mouth gives you lots of clues about your overall health—especially when it comes to your teeth and their surrounding structures. Some things you can decipher for yourself, but for others, you’ll need a dentist and a hygienist to inspect for you. So let’s get into our literary dentist’s chair and do a quick inspection of the other elements of your mouth. Sit back, cue instrumental rendition of “Kokomo,” and we’ll take a look inside (see Figure 3.2).