Dental system

• Enamel – the outer layer of the tooth.
• Dentin – the inner layer and the main part of the tooth.
• Pulp – part of the inside of the tooth that contains the nerve.
• Root – the part of the tooth that secures it into the jaw.

Except for the earliest stages of prenatal development, and possibly the third permanent molars or wisdom teeth, dental development in girls proceeds ahead of that in boys, often by as much as 6 percent. Girls also have slightly smaller crowns and slightly shorter tooth roots than boys.

It is well to bear in mind that every tooth a man will ever have (except the false ones) is already formed or being formed in his jaws at birth. In detail, at birth all of the deciduous teeth are definitely formed and calcification is in process; the six year molars are formed and calcification of their crowns is under way; all of the other permanent teeth have been laid down and await calcification during early childhood.

It is before birth, when these teeth are forming, that we must begin to save the teeth of child and adult. A soft pre-tooth structure laid down in the jaws of the embryo, due to nutritional perversion of the mother, predisposes the teeth to cavities and decay. Finally calcification, due to nutritional perversions and deficiencies, injures both the milky and the permanent teeth.

Parental concerns

Some evidence indicates that infants’ jaws and teeth develop better and more completely if babies are fed breast milk rather than infant formula. To promote their baby’s dental development, pregnant and nursing mothers should do the following:

• Practice good nutrition
• Refrain from prescription and nonprescription drugs, particularly during the first trimester of pregnancy
• Refrain from alcohol, tobacco, and excessive sugar
• Rigorous dental hygiene

Parents must clean and care for their children’s teeth until children are able to do it themselves. Furthermore, parents are the first to teach their children good dental hygiene. After feeding, a baby’s gums should be wiped with clean gauze. Brushing should begin with the first tooth eruption and the remaining gums should be cleaned and massaged. Flossing should begin as soon as all of the baby teeth have erupted.

The rapidity with which decay can advance in baby teeth necessitates periodic dental examinations and cleanings. Pediatric dentists often recommend a first dental appointment at 12 to 18 months of age. Some recommend a first appointment at six months. At the very least, a child should see a dentist by age two-and-a-half or when all of the baby teeth have erupted.

Between two-and-a-half and six years of age is a critical period for dental development. Parents should regularly examine a child’s teeth for signs of decay, crowdedness, or misalignment. A dentist should be consulted if any of the following occurs:

• A child has an inherited disorder that affects the teeth or jaws, such as a protruding or recessed lower jaw.
• Tooth eruption occurs at least a year sooner or later than normal.
• The baby teeth do not erupt properly or seem crowded.
• A baby tooth becomes loose before the age of four or five years.
• A permanent tooth begins to erupt before the baby tooth that it is replacing has been lost.
• Swelling or infection occurs during eruption of the molars.
• A child has difficulty chewing or closing their jaw.
• A child continues to thumb-suck or suck on a pacifier after all of the baby teeth have erupted.

Primary teeth

However in most infants the front teeth begin to peek through the gums between four and eight months. Generally from about six months on, children get four new teeth every four months. Most children have all 20 baby teeth by the age of two-and-a-half to three years.

Baby teeth erupt in pairs on the right and left of the mouth, alternating between the lower and upper jaws, and proceeding from front to back. The 20 primary teeth usually erupt in the following order:

four front teeth or central incisors, first in the lower jaw and then in the upper jaw- four lateral incisors, on each side of the front teeth, uppers before lowers- four first molars, uppers first-  four canines or cuspids, between the lateral incisors and the first molars, usually uppers before lowers- four second molars behind the first molars, lowers first.

Children start losing their baby teeth at about age six, after the permanent front teeth are almost formed beneath the gums. The pressure of the developing permanent teeth causes the roots of the baby teeth to dissolve. Without their anchor in the jaw, the baby teeth loosen and eventually fall out. Most children lose their lower front baby teeth first. The earlier that the baby teeth come in, the earlier they will fall out. Most children have lost all of their baby teeth by age 13.

Permanent teeth

The first permanent teeth, the six-year-molars that become the first permanent molars, erupt, usually between the ages of five and six. If the baby teeth are properly positioned and aligned, the six-year-molars usually erupt properly. If the baby teeth are lost or decayed, the six-year-molars will be too far forward, crowding the permanent teeth that erupt in front of them. However if the six-year-molars erupt properly and if the jaw is large enough, the permanent teeth have a good chance of coming in correctly.

Between the ages of about six and 12 to 14, as the jaw grows, 28 permanent teeth erupt, replacing the primary teeth, incisor for incisor, canine for canine, premolar or bicuspid for molar. The 32 permanent teeth generally erupt in the following order:

four six-year or first molars- four central incisors or front teeth, first in the lower jaw and then in the upper jaw- four lateral incisors, lowers usually first- four canine teeth, lowers first- four first premolars or bicuspids, between the canines and the six-year molars, uppers usually first- four second premolars or bicuspids, between the first premolars and the six-year or first molars, uppers usually first- four second molars, behind the first molars, lowers usually first- four third molars or wisdom teeth at the back, usually between ages 17 and 21.

Teething

Teething (the eruption of the primary teeth through the gums) may cause discomfort or pain. Teething babies may:

be restless and irritable, lose their appetites, sleep poorly, cry excessively, have flushed cheeks, have a slight fever, have congestion, dribble or drool, have red swollen gums at the new teeth sites, rub their gums, suck their thumbs, want something to chew on.

For teething symptoms, parents may massage the gums to relieve discomfort. A frozen teething toy numbs the gums and reduces swelling, although it should not be left on the gum for more than one minute without a break. They may also relieve symptoms by the following:

• Massaging the gums, with or without ice
• Giving the baby a cold teething ring
• Encouraging the baby to chew on cold, wet washcloth or frozen bagel
• Administering acetaminophen (Tylenol)

Eruptions of the permanent teeth are usually much less distressing, although the eruption of the first four broad permanent molars may cause discomfort. As the permanent molars push through the gums, they often leave a flap of tissue over the tooth. If food becomes trapped under the flap, the gums may become sore, swollen, and painful, infected, or abscessed.

Developmental delay

While dental development may be slightly advanced in obese children, development delay can occur with the emergence of some permanent teeth. Delay can be caused by the following:

• Hereditary factors
• Chronic malnutrition
• Developmental disorders
• Hyperdontia (extra or supernumerary teeth)
• Down syndrome
• Radiation or chemotherapy
• Cysts or tumors
• The absence of lateral incisors or wisdom teeth

However, the timing of both primary and permanent tooth eruption can vary by two or more years but the interval between eruption of two symmetric teeth should not be more than 6 months. Conservatively, any sign of considerable delayed eruption should be consulted with a dentist.

Decay

The enamel on baby teeth is thinner and softer than on permanent teeth and decay can move through it very rapidly. About 50 percent of two-year-olds have at least one cavity.

Milky bottle tooth decay occurs when sugary liquids, including milk, juice, or formula, cling to the baby’s teeth, particularly when the child is put to bed with a bottle. The decay occurs most often in the upper front teeth but other teeth also can be affected. If a decayed baby tooth is lost too early, the adjacent teeth may move into the space, causing crooked and overcrowded permanent teeth.

Discolored teeth

Disorders that may cause discoloration of the teeth include:

• Hypoplasia, in which insufficient or irregular enameling of the teeth caused by the administration of tetracycline to a pregnant or nursing mother or to the infant or young child
• Enamel and dentin hypoplasia, in which the enamel and dentin are not calcified (hardened by the depositing of minerals) due to vitamin D deficiency during tooth development
• Hypocalcification, in which the enamel is of poor quality due to genetic factors, extensive plaque deposits, excessive sucking on citrus fruits, or high consumption of very acidic carbonated beverages
• Amelogenesis imperfecta, an inherited defect that causes thin and discolored enamel
• Dentinogenesis imperfecta, a defect of the dentin that causes discoloration and loss of enamel
• Extrinsic enamel coloration due to liquid iron supplements administered for anemia
• Intrinsic enamel coloration due to pigments carried in the blood from tetracycline or other drugs or from excessive fluoride
• Illness or trauma during infancy or early childhood, including infections, high fever, malnutrition, or disorders such as congenital syphilis or Down syndrome, can cause misshapen or discolored teeth.

Wisdom teeth