The teeth develop in sockets within the aveolar processes of the mandibular and maxillary bones. Teeth are unique structures in that two sets form during development. The members of the first set, the "primary" or "deciduous teeth," usually erupt through the gums (gingiva) at regular intervals between the ages of six months and two and one-half years. There are twenty deciduous teeth - ten in each jaw - and they occur from the midline of the mouth toward the side in the following sequence: central incisor (front teeth), lateral incisor, cuspid (canine), first molar (used for grinding) and second molar. The deciduous teeth usually are shed in the same order they appeared. Before this happens, though, their roots are reabsorbed. The teeth are pushed out of their sockets by pressure from the developing "secondary" or "permanent" teeth.
Tooth decay can lead to the destruction and eventual loss of teeth. However, periodontal disease, a disease of the supporting tissue around the tooth, can be so severe that the teeth loosen and fall out. The teeth are seated in sockets in the bones of the upper and lower jaws in alveolar bone, (alveolar means "hollow"). The bone does not hold the teeth in place, rather, the teeth are stabilized by connective tissue called periodontal ligaments that extend between tooth-roots and sockets. The part of the tooth next to the sulcus is extremely difficult to keep free of bacterial plaque, and if not removed constantly, or left undisturbed for a few days, will form tartar - a rough, hard material that adheres to teeth. Plaque and tartar build-up constitute the primary cause of periodontal disease. Periodontal disease begins with mild gum inflammation and becomes more severe over time. Its progression can be divided into four stages. The first stage is gum inflammation or gingivitis, and the gums may become reddish or purple and slightly swollen. They may be tender and they may bleed easily. You may have a sour taste, and your breath may be offensive. You may have no symptoms. The second stage or early periodontitis will involve the sulcus becoming swollen and more inflamed. The sulcus expand its borders creating an even better environment for bacterial growth. As the inflammation spreads and worsens, it will soon attack the periodontal ligament that holds the teeth in place. At this point, a dentist would use a periodontal probe to measure the depth of each periodontal pocket. Periodontitis does not progress steadily, but rather intermittently. Symptoms and the rate of destruction vary. The third stage will see erosion of the gum, pockets will deepen, and more potent forms of bacteria develop. The periodontal ligament and alveolar bone become inflamed. In the fourth stage, there is so much ligament and bone loss that the tooth, no longer stable, will loosen in its socket. Bone loss magnifies pressure from chewing, making the tooth progressively looser. As the tooth looses its support it will fall out or require extraction.
There are essentially three causes for tooth decay: (1) bacteria in the mouth; (2) food for bacteria, and (3) susceptibility to decay such as heredity or age. Tooth decay is a gradual process which ordinarily begins with the outer layer of enamel and then penetrates into the dentin and perhaps even on into the pulp. There is a general consensus that the process of decay begins with plaque formation. Plaque is food debris and their products which form a sticky, concentrated film that adheres to the teeth. Decay usually begins with a small pitted area on the surface of the bone which enlarges to create a soft spot of partially dissolved enamel. This stage of decay is usually painless. The process is kept alive by the addition of sugar in our food that promotes bacterial growth. The longer this process is untreated, the greater the rate of destruction until the decay reaches the dentin, the main substance of the tooth. Dentin is part mineral and part living cells, and decay spreads much faster in dentin than in enamel, and will enlarge forming a cavity. Inflammation of the pulp of the tooth which contains living cells, nerves, and blood vessels -- which most likely, at this stage, produce pain. Survival of the tooth is critical at this stage, and prolonged irritation or inflammation of the tooth may cause its death, or it may lead to abscess formation, a severely inflamed, hollow area under the root. This may require tooth extraction. Antibiotics are normally given before extraction and also to prevent bacteria from spreading through the blood stream causing serious illness. The best cure for tooth decay is prevention. The best way to reduce susceptibility to decay is through the use of fluorides. You can reduce the food supply for bacteria by reducing sugar in your diet. The build-up of plaque can be minimized considerably by frequent brushing and the use of dental floss. Regular, professional care is essential for longevity of tooth life.
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