Pregnancy
A pregnant patient poses a unique set of management considerations for the dentist. Dental care must be rendered to the mother without adversely affecting the developing fetus, and although routine dental care of pregnant patients is generally safe, the delivery of dental care involves some potentially harmful elements, including the use of ionizing radiation and drug administration. Thus, prudent practitioners must balance the beneficial aspects of dentistry while minimizing or avoiding exposure of the patient (and the developing fetus) to potentially harmful procedures.
Additional considerations arise during the postpartum period if the mother elects to breastfeed her infant. Although most drugs are only minimally transmitted from maternal serum to breast milk, and the infant’s exposure is not significant, the dentist should avoid using any drug that is known to be harmful to infants.
Approximately 6 million babies were born in 2014 in the United States. That means that approximately 4 million women are pregnant in the United States at any given time. A typical dental practice serving 2000 patients will have approximately 15 pregnant patients.
The pregnancy rate for women in the United States continued to decline in 2013, to 98.7 per 1000 women aged 15 to 44 years a record low for since 1976. This level was 15% below the 1990 peak (115.8 per 1000). The decline in the overall pregnancy rate included reductions in birth and abortion rates, with the percent decline greater for abortions (35%) than births (10%) over this period. The 2013 abortion rate (17.7) was also a record low.
The average age of women having their first child was a record high of 26 years old in 2013, according to the Centers for Disease Control and Prevention’s (CDC’s) National Vital Statistics Report. That’s an increase of 3.3 years since 1980, when the average age was 22.7. Most of the change took place between 1980 and 2000, when the average rose to 24.9. It stayed relatively stable around 25 until 2008, when it started climbing again to its current high.
Pathophysiology and Complications
Endocrine changes are the most significant basic alterations that occur with pregnancy. They result from the increased production of maternal and placental hormones and from modified activity of target end organs.
Fatigue is a common physiologic finding during the first trimester that may have a psychological impact. A tendency toward syncope and postural hypotension may be present. During the second trimester, patients typically have a sense of well-being and relatively few symptoms. During the third trimester, increasing fatigue and discomfort and mild depression may be reported. Several cardiovascular changes occur as well. Blood volume increases by 40% to 50%, and cardiac output increases by 30% to 50%, but red blood cell (RBC) volume increases by only about 15% to 20%, resulting in a fall in the maternal hematocrit. Despite the increase in cardiac output, blood pressure falls (usually to ≤100/70 mm Hg) during the second trimester, and a modest increase is noted in the last month of pregnancy. This increase in blood volume is associated with high-flow, low-resistance circulation; tachycardia; and heart murmurs, and it may unmask glomerulopathies, peripartum cardiomyopathy, arterial aneurysms, or arteriovenous malformations. A benign systolic ejection murmur is one of the more common findings in more than 90% of pregnant women, which disappears shortly after delivery. A murmur of this type is considered physiologic or functional. However, a murmur that preceded pregnancy or persisted after delivery would require further evaluation for determination of its significance.
During late pregnancy, a phenomenon known as supine hypotensive syndrome may occur that manifests as an abrupt fall in blood pressure, bradycardia, sweating, nausea, weakness, and air hunger when the patient is in a supine position. Symptoms are caused by impaired venous return to the heart that results from compression of the inferior vena cava by the gravid uterus. This leads to decreased blood pressure, reduced cardiac output, and impairment or loss of consciousness. The remedy for the problem is to roll the patient over onto her left side, which lifts the uterus off the vena cava. Blood pressure should rapidly return to normal.
Blood changes in pregnancy include anemia and a decreased hematocrit value. Anemia occurs because blood volume increases more rapidly than RBC mass. As a result, a fall in hemoglobin and a marked need for additional folate and iron occur. The majority of pregnant women have insufficient iron stores, a problem that is exaggerated by significant blood loss. However, there is disagreement over whether or not to routinely provide iron supplementation. Although changes in platelets are usually clinically insignificant, most studies show a mild decrease in platelets during pregnancy. Several blood clotting factors, especially fibrinogen and factors VII, VIII, IX, and X, are increased. As a result of the increase in many of the coagulation factors, combined with venous stasis, pregnancy is associated with a hypercoagulable state. Interestingly, however, the prothrombin time, activated partial thromboplastin time, and thrombin time all fall slightly but remain within the limits of normal nonpregnant values. The overall risk of thromboembolism in pregnancy is estimated to be 1 in 1500 and accounts for 25% of maternal deaths in the United States.
Several white blood cell (WBC) and immunologic changes occur. The WBC count increases progressively throughout pregnancy primarily because of an increase in neutrophils and is nearly doubled by term. The reason for the increase is unclear, but it may be due to elevated estrogen and cortisol levels. This increase of neutrophils may complicate the interpretation of the complete blood count during infection. Also, during pregnancy, the immune system shifts from helper T-cell 1 (TH1) dominance to TH2 dominance. This leads to immune suppression. Clinically, the decrease in cellular immunity leads to increased susceptibility to intracellular pathogens such as cytomegalovirus virus, herpes simplex virus, varicella, and malaria. The decrease in cellular immunity may explain why rheumatoid arthritis frequently improves during gestation because it is a cell-mediated immunopathologic disease. During the postpartum period, rebound and heightened inflammatory activity occur.
Changes in respiratory function during pregnancy include elevation of the diaphragm, which decreases the volume of the lungs in the resting state, thereby reducing total lung capacity by 5% and the functional residual capacity (FRC), the volume of air in the lungs at the end of quiet exhalation, by 20%. Interestingly, the respiratory rate and vital capacity remain unchanged. These ventilatory changes produce an increased rate of respiration (tachypnea) and dyspnea that is worsened by the supine position. Thus, it is not surprising that sleep during pregnancy is impaired, especially during the third trimester.
Pregnancy predisposes the expectant mother to an increased appetite and often a craving for unusual foods. As a result, the diet may be unbalanced, high in sugars, or nonnutritious. This can adversely affect the mother’s dentition and contribute to significant weight gain. Taste alterations and an increased gag response are also common. The pH and production of saliva are probably unchanged. No evidence exists that pregnancy causes or accelerates the course of periodontal disease or dental caries. Nausea and vomiting, or “morning sickness,” complicate up to 70% of pregnancies. Typical onset is between 4 and 8 weeks’ gestation, with improvement before 16 weeks; however, 10% to 25% of women still experience symptoms at 20 to 22 weeks’ gestation, and some women experience this throughout the pregnancy. The cause is not well understood. Some patients may have extreme nausea and vomiting, which can be a cause of dental erosion.
The general pattern of fetal development should be understood when dental management plans are being formulated. Normal pregnancy lasts approximately 40 weeks. During the first trimester, organs and systems are formed (organogenesis). Thus, fetuses are most susceptible to malformation during this period. After the first trimester, the majority of formation is complete, and the remainder of fetal development is devoted primarily to growth and maturation. Thus, the chances of malformation are markedly diminished after the first trimester. A notable exception to this is the fetal dentition, which is susceptible to malformation from toxins or radiation and to tooth discoloration caused by administration of tetracycline.
Complications of pregnancy are infrequent when prenatal care is provided and the mother is healthy. Unfortunately, complications occur more often in expectant mothers who harbor pathogens (oral and extraoral) and smoke and in nonwhites over whites in the United States. Common complications include infection, inflammatory response, glucose abnormalities, and hypertension. Each increases the risks for preterm delivery, perinatal mortality, and congenital anomalies. Insulin resistance is a contributing factor to the development of gestational diabetes mellitus (GDM), which occurs in 2% to 6% of pregnant women. GDM increases the risks for infection and large birth weight babies. Hypertension is of particular interest because it can lead to end-organ damage or preeclampsia, a clinical condition of pregnancy that manifests as hypertension, proteinuria, edema, and blurred vision. Preeclampsia (hypertension with proteinuria) progresses to eclampsia, a life-threatening condition, if seizures or coma develop. The cause of eclampsia is unknown but appears to involve sympathetic overactivity associated with insulin resistance, the renin–angiotensin system, lipid peroxidation, and inflammatory mediators. Complications of pregnancy that are unresponsive to diet modification and palliative care ultimately require drugs or hospitalization for adequate control.
Another consideration related to fetal growth is spontaneous abortion (miscarriage). Spontaneous abortion is the natural termination of pregnancy before the 20th week of gestation; it occurs in approximately 15% of all pregnancies. The most common causes of spontaneous abortion are morphologic or chromosomal abnormalities that prevent successful implantation. It is most unlikely that any dental procedure would be implicated in spontaneous abortion, provided fetal hypoxia and exposure of the fetus to teratogens are avoided. Febrile illness and sepsis also can precipitate a miscarriage; therefore, prompt treatment of odontogenic infection and periodontitis is advised.
Because of immature liver and enzyme systems, fetuses have a limited ability to metabolize drugs. Pharmacologic challenge of fetuses is to be avoided when possible.
During the postpartum period, the mother may suffer from lack of sleep and postpartum depression. Also during the postpartum period, risks for autoimmune disease, particularly rheumatoid arthritis, multiple sclerosis, and thyroiditis, are increased.
Dental Management
Management recommendations during pregnancy should be viewed as general guidelines, not immutable rules. The dentist should assess the general health of the patient through a thorough medical history. Inquiries should be made regarding the patient’s current physician; medications taken; use of tobacco, alcohol, or illicit drugs; history of GDM; miscarriage; hypertension; and morning sickness. If the need arises, the patient’s obstetrician should be consulted, particularly with the use of certain medications ( Box 17.1 ).
P: Patient Evaluation and Risk Assessment (see Box 1.1 )
Potential Issues or Concerns
| A | |
| Antibiotics | If antibiotics are required, consult with the physician. Use those with FDA classification A or B unless otherwise approved by the physician. |
| Analgesics | If analgesics are required, consult with the physician. Acetaminophen is the drug of choice. If other analgesics are required, use with approval of physician. |
| Anesthesia | The usual local anesthetics with vasoconstrictors are safe to use, provided care is taken not to exceed the recommended dose. |
| Anxiety | Avoid the use of most anxiolytics. Short-term use of nitrous oxide can be used, if needed, provided 50% oxygen is used. |
| B | |
| Bleeding | No issues |
| Breathing | Patient may have difficulty breathing in the supine position. |
| Blood pressure | Watch for supine hypotension if patient is in the supine position, most likely in late third trimester. Roll patient on left side if hypotension occurs. |
| C | |
| Chair position | Patient may not be able to tolerate a supine chair position in the third trimester |
| Cardiovascular | Elevated BP could be a sign of preeclampsia; refer to physician for follow-up care. |
| D | |
| Drugs | Avoid all drugs, if possible. If drugs are needed, use FDA category A or B if possible. |
| E | |
| Equipment | Take only necessary radiographs; use a lead apron and thyroid collar. |
| Emergencies | Anticipate the possibility of supine hypotension if in the third trimester. |
| F | |
| Follow-up | Patient should have teeth cleaned during pregnancy and be advised of importance of health and baby’s oral health and not to put the baby to bed with a bottle. |
BP, Blood pressure; FDA, Food and Drug Administration.
Pregnancy is a special event in a woman’s life; hence, it is an emotionally charged experience. Establishing a good patient–dentist relationship that encourages openness, honesty, and trust is an integral part of successful management. This kind of relationship greatly reduces stress and anxiety for both the patient and dentist.
As with all patients, measuring vital signs is important for identifying undiagnosed abnormalities and the need for corrective action. At a minimum, blood pressure and pulse should be measured. Systolic pressure at or above 140 mm Hg and diastolic pressure at or above 90 mm Hg are signs of hypertension (see Chapter 3 ). Also, there is concern if a patient’s blood pressure increases 30 mm or more systolic or an increase of 15 mm Hg in diastolic blood pressure compared with prepregnancy values because this can be a sign of preeclampsia. Confirmed hypertensive values dictate that the patient should be referred to a physician to ensure that preeclampsia and other cardiovascular disorders are properly diagnosed and managed.
Preventive Program. An important objective in planning dental treatment for a pregnant patient is to establish a healthy oral environment and an optimum level of oral hygiene. This essentially consists of a plaque control program that minimizes the exaggerated inflammatory response of gingival tissues to local irritants that commonly accompany the hormonal changes of pregnancy. It has been speculated that periodontal disease is a risk factor for preeclampsia and preterm, low birth weight; however, recent reviews do not support this contention. Maternal plaque control, however, has implications for caries risk for infants. Studies conducted over the past 30 years have shown that reduced oral streptococcal levels in a pregnant mother reduce the risk that her infant will become infected and develop caries.
Acceptable oral hygiene techniques should be taught, reinforced, and monitored. Diet counseling, with emphasis on limiting the intake of refined carbohydrates and carbonated soft drinks, should be provided. Coronal scaling and polishing or root curettage may be performed whenever necessary. Preventive plaque control measures should be provided and emphasized throughout pregnancy, including the first trimester, for benefit to the pregnant mother and the developing baby. Chlorhexidine 0.12% mouth rinse may be used safely during pregnancy, if needed.
The benefits of prenatal fluoride are controversial. Early studies by Glenn and Glenn and associates concluded that a daily 2.2-mg tablet of sodium fluoride administered to mothers during the second and third trimesters in combination with fluoridated water resulted in 97% of the offspring being caries free for up to 10 years. Not only were medical or dental defects, including fluorosis, absent in these children, but an association with decreased premature delivery and increased birth weight was seen in the fluoride treatment group. However, in a later randomized controlled trial of 798 children followed for 5 years after birth, no significant benefit was found with prenatal fluoride compared with placebo. Furthermore, another study failed to find any significant increase in fluoride content of enamel in children who received prenatal fluoride compared to placebo. In 2001, the CDC indicated that there was a lack of evidence to support a recommendation for the use of prenatal fluoride.
Dental Treatment Timing
Other than as part of a good plaque control program, elective dental care is best avoided during the first trimester because of potential vulnerability of fetuses ( Table 17.1 ). The second trimester is the safest period during which to provide routine dental care. Emphasis should be placed on controlling active disease and eliminating potential problems that could occur later in pregnancy or during the immediate postpartum period because providing dental care during these periods is often difficult. Extensive reconstruction or significant surgical procedures are best postponed until after delivery.
| First Trimester | Second Trimester | Third Trimester |
|---|---|---|
| Plaque control | Plaque control | Plaque control |
| Oral hygiene instruction | Oral hygiene instruction | Oral hygiene instruction |
| Scaling, polishing, curettage | Scaling, polishing, curettage | Scaling, polishing, curettage |
| Avoid elective treatment; urgent care only | Routine dental care | Routine dental care |
The early part of the third trimester is still a good time to provide routine dental care. However, after the middle of the third trimester, elective dental care is best postponed. This is because of the increasing feeling of discomfort that many expectant mothers may experience. Prolonged time in the dental chair should be avoided to prevent the complication of supine hypotension. If supine hypotension develops, rolling the patient onto her left side affords return of circulation to the heart. Scheduling short appointments, allowing the patient to assume a semireclined position, and encouraging frequent changes of position can help to minimize problems.
Dental Radiographs
Dental radiography is one of the more controversial areas in the management of pregnant patients. Pregnant patients who require radiographs often have anxiety about the adverse effects of x-rays to their baby. In some instances, their obstetrician or primary care physician may reinforce these fears. In almost all cases involving dental radiography, these fears are unfounded. The safety of dental radiography has been well established, provided features such as fast exposure techniques (e.g., high-speed film or digital imaging), filtration, collimation, lead aprons, and thyroid collars are used. Of all aids, the most important for pregnant patients are protective lead aprons and thyroid collars. In addition, the use of digital radiography markedly reduces radiation exposure, equal to or greater than that with the use of F-speed film.
Ionizing radiation should be avoided, if possible, during pregnancy, especially during the first trimester because developing fetuses are particularly susceptible to radiation damage. However, if dental treatment becomes necessary, radiographs may be required to accurately diagnose and treat the patient. The American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists have published guidelines stating: “Diagnostic radiologic procedures should not be performed during pregnancy unless the information to be obtained from them is necessary for the care of the patient and cannot be obtained by other means.” Therefore, the dentist should understand the risks of ionizing radiation and know how to proceed as safely as possible in the event that radiographs are needed.
The teratogenicity of ionizing radiation is dose dependent; therefore, it is necessary to understand the units of measurement. The absorbed dose is a measure of the energy absorbed by any type of ionizing radiation per unit of mass of any type of matter. The traditional unit of the absorbed dose is the rad (radiation absorbed dose). In recent years, however, there has been a move to use the metric-based International System (IS), and its unit of measurement for absorbed dose is the Gray (Gy): 1 Gy equals 100 rads. Thus, 1 cGy (centigray) equals 1 rad. An additional term, sievert, is used as a measure of equivalent dose to compare the biologic effects of different types of radiation on a tissue or organ. For diagnostic x-ray examinations, 1 sievert equals 1 Gy.
Increased risk of adverse outcomes has not been detected among animals with continuous low-dose exposure less than 5 rad (5 cGy) throughout pregnancy. The National Council for Radiation Protection concluded that exposures less than 5 rads (5 cGy) were not associated with increased risk of malformations. Available animal and human data support the conclusion that no increase in gross congenital anomalies or intrauterine growth retardation occurs as a result of exposures during pregnancy totaling less than 5 cGy (5 rad). Table 17.2 provides a comparison of ionizing radiation exposures expressed in cGy. It is obvious that exposures from typical dental radiographs are less than natural daily background radiation. It should be noted, however, that maternal thyroid exposure to diagnostic radiation in excess of 0.4 mGy has been associated with a slight decrease in birth weight. This finding reinforces the importance of using a thyroid collar on pregnant patients.
| Examination | Effective Dose (µSν) | Equivalent Background Exposure (days) |
|---|---|---|
| INTRAORAL 1 | ||
| Rectangular collimation | ||
| Posterior bitewings: PSP or F-speed film | 5 | 0.6 |
| Full-mouth: PSP or F-speed film | 35 | 4 |
| Full-mouth: CCD sensor (estimated) | 17 | 2 |
| Round collimation | ||
| Full-mouth: D-speed film | 388 | 46 |
| Full-mouth: PSP or F-speed film | 171 | 20 |
| Full-mouth: CCD sensor (estimated) | 85 | 10 |
| EXTRAORAL | ||
| Panoramic 1–3 | 9–24 | 1–3 |
| Cephalometric 1,2,4 | 2–6 | 0.3–0.7 |
| Cone-beam CT 5,6 | ||
| Large field of view | 68–1073 | 8–126 |
| Medium field of view | 45–860 | 5–101 |
| Small field of view | 19–652 | 2–77 |
| Multislice CT | ||
| Head: conventional protocol 6–9 | 860–1500 | 101–177 |
| Head: low-dose protocol 6,8 | 180–534 | 21–63 |
| Abdomen 7 | 5300 | 624 |
| Chest 7 | 5800 | 682 |
| Plain films 10 | ||
| Skull | 70 | 8 |
| Chest | 20 | 2 |
| Barium enema | 7200 | 847 |
1. Data from Ludlow JB, Davies-Ludlow LE, White SC: Patient risk related to common dental radiographic examinations: the impact of 2007 international commission on radiological protection recommendations regarding dose calculation, J Am Dent Assoc 139:1237-1243, 2008.
2. Data from Lecomber AR, Yoneyama Y, Lovelock DJ, et al: Comparison of patient dose from imaging protocols for dental implant planning using conventional radiography and computed tomography, Dentomaxillofac Radiol 30:255-259, 2001.
3. Data from Ludlow JB, Davies-Ludlow LE, Brooks SL: Dosimetry of two extraoral direct digital imaging devices: NewTom cone beam CT and Orthophos Plus DS panoramic unit, Dentomaxillofac Radiol 32:229-234, 2003.
4. Data from Gijbels F, Sanderink G, Wyatt J, et al: Radiation doses of indirect and direct digital cephalometric radiography, Br Dent J 197:149-152, 2004.
5. Data from Pauwels R, Beinsberger J, Collaert B, et al: Effective dose range for dental cone beam computed tomography scanners, Eur J Radiol 81:267-271, 2012.
6. Data from Ludlow JB, Ivanovic M: Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology, Oral Surg Oral Med Oral Pathol Oral Radiol Endod 106:106-114, 2008.
7. Data from Shrimpton PC, Hillier MC, Lewis MA, et al: National survey of doses from CT in the UK: 2003, Br J Radiol 79:968-980, 2006.
8. Data from Loubele M, Jacobs R, Maes F, et al: Radiation dose vs. image quality for low-dose CT protocols of the head for maxillofacial surgery and oral implant planning, Radiat Prot Dosimetry 117:211-216, 2005.
9. Data from Loubele M, Bogaerts R, Van Dijck E, et al: Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications, Eur J Radiol 71:461-468, 2009.
10. Data from European Commission: Referral guidelines for imaging, Radiation Protection 118, 2007. http://www.sergas.es/Docs/Profesional/BoaPraticaClinica/RP118.pdf
Teratogenicity is also dependent on the gestational age of the fetus at the time of exposure. During the organogenesis period (from the end of the 2nd to the 8th week postconception), fetuses are extremely sensitive to the teratogenic effect of ionizing radiation, particularly the central nervous system (CNS) between the 8th and 15th weeks of pregnancy. From the 16th to the 25th week, there is a reduction in the radiosensitivity of the CNS and in many of the other organs. After the 25th week, the CNS becomes relatively radioresistant, and major fetal malformations and functional anomalies are highly improbable.
When risks of dental radiography are further assessed during pregnancy, three reports should be kept in mind. The first states that the maximum risk attributable to 1 cGy (which is more than 1000 full-mouth series with E-speed film and rectangular collimation or 10%–20% of the threshold dose) of in utero radiation exposure is estimated to be approximately 0.1%. This is a quantity thousands of times less than the normal anticipated risks of spontaneous abortion, malformation, or genetic disease. The risk of a first-generation fetal defect from a dental radiographic examination is estimated to be 9 in 1 billion. The third report found that the gonadal dose to women, after full-mouth radiography using a lead apron, is less than 0.01 µSv, which is at least 1000-fold below the threshold shown to cause congenital damage to newborns. These figures indicate that with use of a lead apron, rectangular collimation, and E-speed film or faster techniques, one or two intraoral films are truly of minute significance in terms of radiation effects on a developing fetus. In terms that can be explained to a patient, one should consider the following: The gonadal or fetal dose of two periapical dental films (when a lead apron is used) is 700 times less than 1 day of average exposure to natural background radiation in the United States.
Despite the negligible risks of dental radiography, dentists should not be cavalier regarding its use during pregnancy (or at any other time, for that matter). Radiographs should be used selectively and only when necessary and appropriate to aid in diagnosis and treatment. Bitewing, panoramic, or selected periapical films are recommended for minimizing patient dose. To further reduce the radiation dose, the following measures should be used: rectangular collimation, E-speed or F-speed film or faster techniques (digital imaging reduces radiographic exposure by at least 50% compared with E-speed exposures), lead shielding (abdominal and thyroid collar), high kilovoltage (kV) or constant beams, and an ongoing quality assurance program.
An additional consideration is the pregnant dental auxiliary or dentist. The maximum permissible radiation dose for whole-body exposure of the pregnant dental care worker is 0.005 Gy or 5 mSv per year. This is equivalent to the maximum permissible radiation dose of the nonoccupationally exposed public and 10-fold less than the level of occupationally exposed nonpregnant workers (50 mSv). The National Council on Radiation Protection and Measurements reports that production of congenital defects is negligible from fetal exposures of 50 mSv. To further ensure safety, a pregnant operator should wear a film badge; stand more than 6 feet from the tube head; and position herself at between 90 and 130 degrees of the beam, preferably behind a protective wall ( Fig. 17.1 ). When these guidelines are followed, no contraindication to pregnant women operating an x-ray machine occurs. However, dentists should familiarize themselves with federal (Code of Federal Regulations, Code 10, Part 20, Section 20.201) and state regulations that would supersede these guidelines.
Drug Administration
Another controversial area in the treatment of pregnant dental patients is drug administration. The principal concern is that a drug may cross the placenta and be toxic or teratogenic to the fetus. Additionally, any drug that is a respiratory depressant may cause maternal hypoxia, resulting in fetal hypoxia, injury, or death.
Ideally, drug administration should be avoided during pregnancy, especially during the first trimester. However, adhering to this rule is sometimes impossible. Actually, 75% of pregnant women in the United States are taking some type of medication. Fortunately, most of the commonly used drugs in dental practice can be given during pregnancy with relative safety, although a few exceptions are notable. Table 17.3 presents a suggested approach to drug usage for pregnant patients.
| Agent | FDA PR * Category | Safe During Pregnancy? | Safe During Breastfeeding? |
|---|---|---|---|
| Analgesics and Antiinflammatories † | |||
| Acetaminophen | B | Yes | Yes |
| Aspirin | C/D | Avoid | Avoid |
| Codeine | C | Use with caution | Yes |
| Glucocorticoids (dexamethasone, prednisone) | C | Avoid ‡ | Yes |
| Hydrocodone | C | Use with caution | Use with caution |
| Ibuprofen § | C/D | Avoid use in third trimester | Yes |
| Oxycodone | B | Use with caution | Use with caution |
| Antibiotics ¶ # | |||
| Amoxicillin | B | Yes | Yes |
| Azithromycin | B | Yes | Yes |
| Cephalexin | B | Yes | Yes |
| Chlorhexidine (topical) | B | Yes | Yes |
| Clarithromycin | C | Use with caution | Use with caution |
| Clindamycin | B | Yes | Yes |
| Clotrimazole (topical) | B | Yes | Yes |
| Doxycycline | D | Avoid | Avoid |
| Erythromycin | B | Yes | Use with caution |
| Fluconazole | C/D | Yes (single-dose regimens) | Yes |
| Metronidazole | B | Yes | Avoid; may give breast milk an unpleasant taste |
| Nystatin | C | Yes | Yes |
| Penicillin | B | Yes | Yes |
| Terconazole (topical) | B | Yes | Yes |
| Tetracycline | D | Avoid | Avoid |
| Local Anesthetics | |||
| Articaine | C | Use with caution | Use with caution |
| Bupivacaine | C | Use with caution | Yes |
| Lidocaine (with or without epinephrine) | B | Yes | Yes |
| Mepivacaine (with or without levonordefrin) | C | Use with caution | Yes |
| Prilocaine | B | Yes | Yes |
| Benzocaine (topical) | C | Use with caution | Use with caution |
| Dyclonine (topical) | C | Yes | Yes |
| Lidocaine (topical) | B | Yes | Yes |
| Tetracaine (topical) | C | Use with caution | Use with caution |
| Sedatives | |||
| Benzodiazepines | D/X | Avoid | Avoid |
| Zaleplon | C | Use with caution | Use with caution |
| Zolpidem | C | Use with caution | Yes |
| Emergency Medications | |||
| Albuterol | C | Steroid and β 2 -agonist inhalers are safe | Yes |
| Diphenhydramine | B | Yes | Avoid |
| Epinephrine | C | Use with caution | Yes |
| Flumazenil | C | Use with caution | Use with caution |
| Naloxone | C | Use with caution | Use with caution |
| Nitroglycerin | C | Use with caution | Use with caution |
* FDA PR: U.S. Food and Drug Administration Pregnancy Risk. See Table 1 for FDA PR category definitions.
† In the case of combination products (such as oxycodone with acetaminophen), the safety with respect to either pregnancy or breastfeeding is dependent on the highest-risk moiety. In the example of oxycodone with acetaminophen, the combination of these two drugs should be used with caution, because the oxycodone moiety carries a higher risk than the acetaminophen moiety.
‡ Oral steroids should not be withheld from patients with acute severe asthma.
§ Ibuprofen is representative of all nonsteroidal antiinflammatory drugs. In breastfeeding patients, avoid cyclooxygenase selective inhibitors such as celecoxib, as few data regarding their safe use in this population are available, and avoid doses of aspirin higher than 100 milligrams because of risk of platelet dysfunction and Reye syndrome.
¶ Antibiotic use during pregnancy: The patient should receive the full adult dose and for the usual length of treatment. Serious infections should be treated aggressively. Penicillins and cephalosporins are considered safe. Use higher-dose regimens (such as cephalexin 500 mg three times per day rather than 250 mg three times per day), as they are cleared from the system more quickly because of the increase in glomerular filtration rate in pregnancy.
# Antibiotic use during breastfeeding: These agents may cause altered bowel flora and, thus, diarrhea in the baby. If the infant develops a fever, the clinician should take into account maternal antibiotic treatment.
Before prescribing or administering a drug to a pregnant patient, the dentist should be familiar with the U.S. Food and Drug Administration (FDA) categorization of prescription drugs for pregnancy based on their potential risk of fetal injury. These pregnancy risk classification categories, although not without limitations, are meant to aid clinicians and patients in making decisions about drug therapy. Counseling should be provided to ensure that women who are pregnant clearly understand the nature and magnitude of the risk associated with a drug. In 2008, the FDA announced that it was eliminating the current pregnancy risk classification system due to inadequacies; however, at this time the original system is still in place.
The current five pregnancy labeling categories are as follows ( Fig. 17.2 ):
| A | Controlled studies in humans have failed to demonstrate a risk to the fetus, and the possibility of fetal harm appears remote. |
| B | Animal studies have not indicated fetal risk, and human studies have not been conducted; or animal studies have shown a risk, but controlled human studies have not. |
| C | Animal studies have shown a risk, but controlled human studies have not been conducted, or studies are not available in humans or animals. |
| D | Positive evidence of human fetal risk exists, but in certain situations, the drug may be used despite its risk. |
| X | Evidence of fetal abnormalities and fetal risk exists based on human experience, and the risk outweighs any possible benefit of use during pregnancy. |
Drugs in categories A or B are preferable for prescribing during pregnancy. However, many commonly prescribed drugs used in dentistry fall into category C, and thus the safety of their use is often uncertain. Drugs in category C present the greatest difficulty for the dentist and the physician in terms of therapeutic and medicolegal decisions, and therefore, consultation with the physician may be needed ( Fig. 17.2 ).
Physicians may advise against the use of some of the approved drugs or conversely may suggest the use of an uncertain or questionable drug. The FDA categories are general guidelines and may be incomplete, and therefore, differences in practice are not unusual. An example of the occasional use of a questionable drug would be a category C narcotic analgesic for a pregnant patient who is in severe pain.
Local Anesthetics.
Common local anesthetics (lidocaine, prilocaine) administered with epinephrine are generally considered safe for use during pregnancy. Articaine, bupivacaine, and mepivacaine are typically safe, although some caution should be exercised. Although both the local anesthetic and the vasoconstrictor cross the placenta, subtoxic threshold doses have not been shown to cause fetal abnormalities. Because of adverse effects associated with high levels of local anesthetics, it is important not to exceed the manufacturers recommended maximum dose.
Some topical anesthetics, including benzocaine, dyclonine, and tetracaine, may be acceptable but used with caution. There is no problem with topical lidocaine.
Analgesics.
The analgesic of choice during pregnancy is acetaminophen. Aspirin and nonsteroidal antiinflammatory drugs convey risks for constriction of the ductus arteriosus, as well as for postpartum hemorrhage and delayed labor (see Table 17.3 ). The risk of these adverse events increases when agents are administered during the third trimester. Therefore, it is best to avoid these analgesics (especially in the third trimester) or use them with caution. Risk also is more closely associated with prolonged administration, high dosage, and selectively potent antiinflammatory drugs, such as glucocorticoids and indomethacin. Most opioids, including codeine, Demerol, and propoxyphene, are associated with multiple congenital defects and should be used cautiously and only if needed. The safety of hydrocodone and oxycodone is unclear, but because there is no possibility of adverse respiratory effects, it is best to avoid them or use them with caution.
Antibiotics.
Penicillins (including amoxicillin), erythromycin (except in estolate form), cephalosporins, metronidazole, and clindamycin are generally considered to be safe for expectant mothers and developing fetuses. The use of tetracycline, including doxycycline, is contraindicated during pregnancy. Tetracyclines bind to hydroxyapatite, causing brown discoloration of teeth, hypoplastic enamel, inhibition of bone growth, and other skeletal abnormalities. Clarithromycin should be avoided or use with caution.
Antibiotics and Oral Contraceptives.
The concern for potential interactions between antibiotics and oral contraceptives requires mention in this chapter. This concern arises from the ability of select antibiotics such as rifampin, an antituberculosis drug, to reduce plasma levels of circulating oral contraceptives. It has been speculated that this interaction also may be seen with other antibiotics; however, studies to date regarding other antibiotics have been less convincing. To address this concern, the American Dental Association Council on Scientific Affairs issued the following recommendations when prescribing antibiotics to a female patient who takes oral contraceptives: “The dentist should (1) advise the patient of the potential risk of the antibiotic’s reducing the effectiveness of the oral contraceptive, (2) recommend that the patient discuss with her physician the use of an additional nonhormonal means of contraception, [and] (3) advise the patient to maintain compliance with oral contraceptives when concurrently using antibiotics.” The application of these recommendations appears prudent until the findings of larger studies become available. In general, dentists should provide treatment for acute infection irrespective of the stage of pregnancy.
Anxiolytics.
Few anxiolytics are considered safe to use during pregnancy. Benzodiazepines, zaleplon, and zolpidem should be avoided. However, a single, short-term exposure to nitrous oxide–oxygen (N 2 O–O 2 ) for less than 35 minutes is not thought to be associated with any human fetal anomalies, including low birth rate. In contrast, however, chronic occupational exposure to N 2 O–O 2 has been associated with spontaneous abortion and reduced fertility in humans. Nitrous oxide may cause inactivation of methionine synthetase and vitamin B 12 , resulting in altered DNA metabolism that can lead to cellular abnormalities in animals and birth defects. Accordingly, the following guidelines are recommended if N 2 O–O 2 is used during pregnancy:
- •
Use of N 2 O–O 2 inhalation should be minimized to 30 minutes.
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At least 50% oxygen should be delivered to ensure adequate oxygenation at all times.
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Appropriate oxygenation should be provided to avoid diffusion hypoxia at the termination of administration.
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Repeated and prolonged exposures to nitrous oxide are to be prevented.
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The second and third trimester are safer periods for treatment because organogenesis occurs during the first trimester.
An additional consideration involves female dentists or dental auxiliaries who are pregnant. These individuals should not be exposed to persistent trace levels of nitrous oxide in the operatory. The use of appropriate scavenging equipment can help alleviate this problem. Female dental health care workers who are chronically exposed to nitrous oxide for more than 3 hours per week, when scavenging equipment is not used, have decreased fertility and increased rates of spontaneous abortion. Implementation of National Institute for Occupational Safety and Health recommendations can reduce occupational exposure to nitrous oxide ( Box 17.2 ).
- 1.
Inspect nitrous oxide equipment and replace defective tubing and parts.
- 2.
Check pressure connections for leaks; fix leaks.
- 3.
Ensure that mask fits well and is secure. Check that the reservoir bag is not over- or underinflated.
- 4.
Provide operatory ventilation of 10 or more room air exchanges per hour.
- 5.
Use a scavenging system and appropriate mask sizes. Vacuum should provide up to 45 L/min.
- 6.
Connect and turn on the vacuum pump of the scavenging system before providing nitrous oxide.
- 7.
Regularly conduct air sampling. Maintain low exposure limits (e.g., 25 ppm *
* This limit is a National Institute for Occupational Safety and Health recommendation. In contrast, Yagiela suggests a time-weighted average lower limit of 100 ppm for an 8-hour workday.
) when pregnant dental health care workers are involved.
Nursing.
A potential problem arises when a nursing mother requires the administration of a drug in the course of dental treatment. The concern is that the administered drug may enter the breast milk and be transferred to the nursing infant, in whom exposure may result in adverse effects.
Data on which to draw definitive conclusions about drug dosages and effects via breast milk are limited. However, retrospective clinical studies and empiric observations, coupled with known pharmacologic pathways, allow recommendations to be made. The AAP concludes that “most drugs likely to be prescribed to the nursing mother should have no effect on milk supply or on infant well-being.” A significant fact is that the amount of drug excreted in the breast milk usually is not more than about 1% to 2% of the maternal dose. Therefore, most drugs are of little pharmacologic significance to infants.
Agreement exists that a few drugs, or categories of drugs, are definitely contraindicated for nursing mothers. These include lithium, anticancer drugs, radioactive pharmaceuticals, and phenindione. Table 17.3 contains recommendations adapted from the AAP regarding the administration of commonly used dental drugs during breastfeeding. As with drug use during pregnancy, individual physicians may wish to modify these recommendations, which should be viewed only as general guidelines for treatment.
In addition to careful drug selection, nursing mothers may take the drug just after breastfeeding and avoid nursing for 4 hours or longer if possible. This should result in reduced drug concentrations in the breast milk.
Treatment Planning Modifications
No technical modifications are required for pregnant patients. However, full-mouth radiographs, reconstruction, crown and bridge procedures, and significant surgery are best delayed until after pregnancy. A prominent gag reflex also may dictate a delay in certain dental procedures. Many patients have a concern about mercury exposure from amalgam fillings. In 2009, the FDA concluded that “although data are limited, existing data do not suggest that fetuses are at risk for adverse health effects due to maternal exposure to mercury vapors from dental amalgam.” The FDA does note, however, that “maternal exposures are likely to increase temporarily when new dental amalgams are inserted or existing dental amalgams are removed.” The FDA furthermore concluded that “existing data support a finding that infants are not at risk for adverse health effects from the breast milk of women exposed to mercury vapors from dental amalgams.” Practitioners should be aware, however, that several European countries and Canada have national recommendations advising dentists to limit or avoid the placement and replacement of amalgams during pregnancy.
As for the risk to dental personnel from exposure to dental amalgam, the FDA concludes that “existing data indicate that dental professionals are generally not at risk for mercury toxicity except when dental amalgams are improperly used, stored, triturated, or handled.”
Oral Complications and Manifestations
The most common oral complication of pregnancy is pregnancy gingivitis ( Fig. 17.3 ). However, the incidence of dental caries increases as well. This condition results from an exaggerated inflammatory response to local irritants and less than meticulous oral hygiene during periods of increased secretion of estrogen and progesterone and altered fibrinolysis. Pregnancy gingivitis begins at the marginal and interdental gingiva, usually in the second month of pregnancy. Progression of this condition leads to fiery red and edematous interproximal papillae that are tender to palpation. In approximately 1% of gravid women, the hyperplastic response may exacerbate in a localized area, resulting in a pyogenic granuloma or “pregnancy tumor” ( Fig. 17.4 ). The most common location for a pyogenic granuloma is the labial aspect of the interdental papilla. The lesion is generally asymptomatic; however, tooth brushing may traumatize the lesion and cause bleeding. Hyperplastic gingival changes become apparent around the second month and continue until after parturition, at which time the gingival tissues usually regress and return to normal, provided proper oral hygiene measures are implemented and any calculus present is removed. Surgical or laser excision is occasionally required if symptoms, bleeding, or interference with mastication dictates. Pregnancy does not cause periodontal disease but may modify and worsen what is already present.
