Composite resins, or tooth-colored fillings, provide good durability and resistance to fracture in small- to mid-size fillings that need to withstand moderate pressure from the constant stress of chewing. They can be used on either front or back teeth. They are a good choice for people who prefer that their fillings look more natural. Tooth-colored fillings are now used more often than amalgam or gold fillings, probably due to cosmetics. In a society focused on a white, bright smile, people tend to want fillings that blend with the natural color of their teeth.
What’s in Your Mouth?
To understand what happens when your teeth decay, it’s helpful to know what’s in your mouth naturally. Here are a few of the elements:
Saliva — Your mouth and teeth are constantly bathed in saliva. We never give much thought to our spit, but this fluid is remarkable for what it does to help protect our oral health. Saliva keeps teeth and other parts of your mouth moist and washes away bits of food. Saliva contains minerals that strengthen teeth. It includes buffering agents. They reduce the levels of acid that can decay teeth. Saliva also protects against some viruses and bacteria.
Plaque — Plaque is a soft, gooey substance that sticks to the teeth a bit like jam sticks to a spoon. Like the slime that clings to the bottom of a swimming pool, plaque is a type of biofilm. It contains large numbers of closely packed bacteria, components taken from saliva, and bits of food. Also in the mix are bacterial byproducts and white blood cells. Plaque grows when bacteria attach to the tooth and begin to multiply. Plaque starts forming right after a tooth is cleaned. Within an hour, there’s enough to measure. As time goes on, the plaque thickens. Within two to six hours, the plaque teems with bacteria that can cause cavities and periodontal (gum) disease.
Calculus — If left alone long enough, plaque absorbs minerals from saliva. These minerals form crystals and harden into calculus. Then new plaque forms on top of existing calculus. This new layer can also become hard.
Bacteria — We have many types of bacteria in our mouths. Some bacteria are good; they help control destructive bacteria. When it comes to decay, Streptococcus mutans and Lactobacilli are the bacteria that cause the most damage to teeth.
How Your Teeth Decay
The bacteria in your mouth need food to live and multiply. When you eat sugary foods, or even starches such as rice, the bacteria use them as food, too. The bacteria then produce acids that can dissolve tooth enamel (outer layer of the tooth).
It’s not just candy and ice cream we’re talking about. All carbohydrate foods eventually break down into simple sugars. Some of this process begins in the mouth.
Foods that break down into simple sugars in the mouth are called fermentable carbohydrates. These include the obvious sugary foods, such as cookies, cakes, soft drinks and candy. But they also include pretzels, crackers, bananas, potato chips and breakfast cereals.
Bacteria in your mouth turn the sugars in these foods into acids. These acids begin to dissolve the mineral crystals in teeth. The more times you eat each day, the more times your teeth are exposed to an acid attack.
This attack can lead to tooth decay, also known as dental caries or cavities. First, the acid begins to dissolve calcium and phosphate crystals inside a tooth. A white spot may appear on the enamel in this weakened area. But the loss of minerals develops beneath the surface of the enamel. The surface may still be smooth.
At this stage, the tooth can be repaired with the help of fluoride, proteins and minerals (calcium and phosphate) in the saliva. The saliva also helps reduce the acid levels from bacteria that attack the tooth.
Once the decay breaks through the enamel to cause a cavity, the damage is permanent. A dentist must clean out the decay and fill the cavity. Left untreated, the decay will get worse. It can destroy a tooth all the way through the enamel, through the inside dentin layer and down to the pulp or nerve of the tooth. That’s why it is important to treat caries at a very early stage, when the process can be reversed.