Lesson 1: Prenatal Care Overview: The health care provider gains an understanding of how pregnancyrelated events are associated with tooth development. Goals: The health care provider will be able to describe: ¬ Why expectant mothers need to maintain healthy teeth and gums during their entire pregnancy to help reduce the risks of premature births and low birth weight babies ¬ The link between pregnant women’s nutrient intake and their oral health ¬ The effects of nutrient deficiencies of a pregnant woman on her child’s tooth development ¬ The transmission of mutans streptococci from caregiver to child ¬ Orofacial growth and development
Key Terms: Ameloblasts
enamel forming cells
Early Childhood Caries
infectious disease that initially affects the teeth of infants and young children; rapidly developing type of decay that primarily affects the 4 upper front teeth, although lower teeth and molars may also be affected
Enamel Hypoplasia
defective or incomplete development of enamel
Mutans Streptococci
cariogenic bacteria
Odontoblasts
dentin and pulp forming cells
Periodontal Disease
infection of the supporting structures of the teeth (gums, bones, and ligaments) which, if left untreated, can lead to tooth loss
Permanent Teeth
second set of teeth that erupt into a
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person’s mouth; also known as secondary or adult teeth Primary Teeth
first set of teeth that erupt into a person’s mouth; also known as baby or deciduous teeth
Prenatal Counseling It is important to provide prenatal counseling that includes information regarding: • pre and postnatal parental oral health • prevention of Early Childhood Caries (ECC), formerly known as Baby Bottle Tooth Decay (BBTD) Studies show that the transmission of mutans streptococci to a child’s mouth usually occurs from a child’s primary caretaker. Therefore, this information should be shared with caregivers so they will see how important it is for them to improve their oral health, which would decrease the bacterial burden and, potentially decrease the child’s risk for dental decay. Expectant couples should be encouraged to gain, and maintain, good personal oral health during the prenatal period and beyond. Decreasing the primary caretakers’ mutans streptococci levels may decrease the child’s risk of developing early childhood caries. Coordination is needed between dental care and obstetrical care providers to enhance the oral health of pregnant women. Obstetricians are strongly encouraged to recommend an oral health evaluation early in pregnancy, given the possible association between maternal periodontal disease and delivery of pre-term babies. Pregnancy is a period when proper maternal health care and patient education can have a profound effect on the oral health of both the mother and child. •
Pregnant women with gum disease are seven and a half times more likely to have a premature, low birth weight baby.
•
Alcohol and smoking are also risk factors.
The enzyme produced by infected gums, cytokines, is the same enzyme that pregnant women produce to induce labor when it is time to give birth. When this enzyme enters the blood stream from the gums before the baby is due, it may induce premature delivery.
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Periodontal disease is also linked to low birth weight babies (those born weighing less than five pounds, eight ounces). Low birth weight babies are prone to severe physical problems. As young children, they may continue to have problems and are more likely to develop early childhood caries. Prevention of early childhood caries begins with intervention in the perinatal and prenatal periods. Women should be advised to optimize their own nutrition during the third trimester and their infant’s nutrition during the first year, when the enamel of the child’s teeth is undergoing maturation. Nutrition and oral health are closely linked. Diet and its nutritional consequences can have a profound impact on tooth development and good oral health, and on the development and progression of diseases of the oral environment. Gestational Development At two months of gestation, primary tooth development begins. Permanent teeth begin to form several months before birth. A pregnant woman’s nutrient intake must therefore supply the pre-eruptive teeth with the appropriate building materials. Teeth are formed by mineralization of a protein matrix. The mineralization process begins as early as four months of gestation and continues into late adolescence as the root structures are completed. The calcium, phosphorus, and other minerals that are needed to form a baby’s developing teeth are taken from the mother’s bloodstream, and unless she is actually undernourished, there is little that will interfere with the ability of the baby’s toothforming cells to turn these basic minerals into normal dentin and enamel cells. About five to six months before birth, some parts of all the twenty primary teeth begin to develop in the baby’s jaws. If they are in their proper place, they act as foundations for the dental arch and help keep all the other teeth in their proper positions. For a full term infant (37-40 weeks gestation), a part of the first permanent molar begins to form before birth. The rest of the permanent teeth begin to form right after birth. Between four and twelve months after birth, the first teeth usually appear in an infant’s mouth. A normal set of teeth includes eight incisors in the front of the mouth, four canine teeth in the corners of the mouth, and eight molars in the back. All twenty primary teeth are generally in position by three to four years of age.
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Why talk about this now? Because now - before birth - is when the molar teeth are beginning to form. How resistant these caries-sensitive teeth will be depends on how well they mineralize. The mother, by balancing the necessary calcium, phosphorus, and vitamins in her bloodstream, contributes to successful tooth development. However, an imbalance in these minerals occurs most often from a high fever or a viral infection, not from a nutritional lack. Enamel hypoplasia results when the enamel matrix formation is disturbed. The result may be an irregularity of tooth form, color, or surface. Factors that may contribute to enamel hypoplasia include: 1. 2. 3. 4. 5. 6. 7. 8.
severe nutritional deficiency, particularly rickets fever producing diseases, such as measles, chickenpox, and scarlet fever congenital syphilis hypoparathyroidism birth injury prematurity Rh hemolytic disease infection
Hypoplasia is common in children with low birth weight or systemic illness in the neonatal period. There is considerable evidence that malnutrition or undernutrition during the prenatal period is a cause of hypoplasia. A consistent association exists between clinical hypoplasia and early childhood caries. Hypoplastic enamel of primary teeth is usually a manifestation of the mother’s general health during pregnancy. However, hypoplastic permanent first molars and anterior teeth could be a result of an infection or intervention (such as pharmaceutical) prior to age three. Children born prematurely or at very low birth weight may have hypoplastic enamel in both primary and permanent dentitions due to disturbances during enamel formation and maturation.
Examples of developmental defects
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Embryonic Development The orofacial complex is developed through a series of events that are genetically controlled. It is important for all health providers to have developmental and growth information to better understand this section of the body. Third and fourth weeks
Germ cell layers (ectoderm, mesoderm, and endoderm) - essential in developing parts of the face and mouth.
Third to sixth week
Lips, parts of the nose and jaws Development of the palate
Sixth week
Teeth begin to develop from a band of oral epithelium on the upper and lower jaws. From this tissue tooth buds form and eventually a tooth germ develops with ameloblasts and odontoblasts. With the dentin mineralizing and enclosing the pulp, the ameloblasts will begin to form enamel.
Any time during these developmental stages, alterations in the enamel content can affect not only the clinical appearance of the teeth but also its risk for dental caries.
CHRONOLOGY OF THE HUMAN DENTITION
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Tooth
Tooth Formation Begins
Tooth Eruption
Root Completed
Exfoliation
Primary Dentition - Maxillary Central Incisor
4 mo in utero
8-12 mos
1 _ yrs
6-7 yrs
Lateral Incisor
4 _ mo in utero
9-13 mos
2 yrs
7-8 yrs
Cuspid
5 mo in utero
16-22 mos
3 _ yrs
10-12 yrs
First molar
5 mo in utero
13-19 mos
2 _ yrs
9-11 yrs
Second molar
6 mo in utero
25-33 mos
3 yrs
10-12 yrs
Primary Dentition - Mandibular Central Incisor
4 _ mo in utero
6-10 mos
1 _ yrs
6-7 yrs
Lateral Incisor
4 _ mo in utero
10-16 mos
1 _ yrs
Cuspid
5 mo in utero
17-23 mos
3 _ yrs
First molar
5 mo in utero
14-18 mos
2 _ yrs
9-11 yrs
Second molar
6 mo in utero
22-31 mos
3 yrs
10-12 yrs
7-8 yrs 9-12 yrs
Permanent Dentition - Maxillary Central Incisor
3-4 mos
7-8 yrs
10 yrs
Lateral Incisor
10-12 mos
8-9 yrs
11 yrs
4-5 mos
11-12 yrs
13-15 yrs
1 _ -1 _ yrs
10-11 yrs
12-13 yrs
2-2 _ yrs
10-12 yrs
12-14 yrs
at birth
6-7 yrs
9-10 yrs
2 _ -3 yrs
12-13 yrs
14-16 yrs
Cuspid First bicuspid Second bicuspid First molar Second molar
Permanent Dentition - Mandibular Central Incisor
3-4 mos
6-7 yrs
9 yrs
Lateral Incisor
3-4 mos
7-8 yrs
10 yrs
Cuspid
4-5 mos
9-10 yrs
12-14 yrs 12-13 yrs
First bicuspid
1 _ - 2 yrs
10-12 yrs
Second bicuspid
_ - 2 _ yrs
11-12 yrs
13-14 yrs
6-7 yrs
9-10 yrs
11-13 yrs
14-15 yrs
First molar Second molar
at birth 2 _ - 3 yrs
Other Concerns
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Three things that may happen to the expectant mother that could directly affect her baby’s teeth: 1. If the mother gets a fever from a virus or some other infection (a common occurrence between the fifth and ninth months of pregnancy), the delicate balance of calcium and phosphorous in her bloodstream could be upset. This affects the quality and quantity of tooth structure that is forming in the fetus. This disruption in tooth structure formation will continue for as long as it takes the mother’s system to regain its balance. 2. If the mother’s physician gives her an antibiotic containing tetracycline, the developing teeth might become stained. Later, when the teeth come into the mouth, they will be discolored. The color may range from dark grey through yellow to bright orange, depending on how much tetracycline the mother got, how long she took it, and at what time during pregnancy it was consumed. Most physicians don’t prescribe tetracycline for pregnant mothers; its use is becoming rare. Nevertheless, a woman who is pregnant but doesn’t “show” should tell or be asked by any healthcare provider - general physician, dentist, chiropractor - whether she’s expecting. 3. If the expectant mother gives birth before term, it is possible that the child’s teeth will be affected. There is some evidence today that full term children have fewer cavities. This is because those areas of the teeth that are mineralizing just around the time of birth are the ones most susceptible to decay.
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