Oral cavity is generally regarded as the mirror of human health as it reflects almost all the systemic alterations occurring in our body. During the dynamic stages of pregnancy, body is subjected to both reversible and irreversible hormonal changes which in turn affects oral cavity. Oral health of the mother can have significant implications on birth outcomes and infant oral health. Maternal periodontal disease has been associated with pre-term birth, development of preeclampsia, and low birth weight infants.

The oral flora of mother is transmitted to the newborn, and increased maternal cariogenic flora predisposes the incidence of infant caries. So preconception, pregnancy, or intrapartum treatment of oral diseases can greatly improve general as well as oral maternal health, pregnancy outcomes, and new born dental health. This article reviews the dental health problems affecting pregnant women along with management protocols and preventive strategies for dental diseases like caries and periodontitis. A note on prenatal counselling, risk of medication to both mother and foetus and appropriate scheduling of dental procedures during pregnancy has also been included.

Pregnancy is a unique period during a woman's life where several complex physiological changes occur in the body which can affect oral health [1]. A women’s encounter with most prevalent diseases of oral cavity such as periodontitis or dental caries in the preconception and pregnancy period can affect her own general health status and pregnancy outcome. Although preventable through noninvasive interventions, both these oral problems are prevalent in women of childbearing age, particularly among low-income groups.

The major oral changes seen in pregnant ladies such as caries, gingivitis, periodontitis and gingival hyperplasia are associated with higher levels of circulating estrogen [2]. A high level of estrogen is associated with gingivitis and gingival hyperplasia while melasma in the midface region is associated with progesterone [3]. Several studies have linked maternal oral health to pregnancy outcomes and dental health of offspring. Preterm delivery, low birth weight and high risk of early caries in offspring are some of the parameters that have been corroborated to poor maternal oral health [4].

Pregnant patients often face several impediments in their quest for achieving optimal oral health. The overcautious approach of dental staff to pregnant patients can be due to lack of knowledge or experience in treatment, fear of medico-legal action or ignorance of accepted practice guidelines. This is often compounded by the patients past negative oral health experiences [5]. It is imperative that an effective model for management of dental problems in the pregnant patient should be designed which should encompass a multidisciplinary partnership between dental and medical professionals [6].

Systemic Changes in Pregnancy
The changes in hormonal milieu during pregnancy and puerperium cause numerous physiological systemic changes. The cardiovascular changes in pregnancy include increase in cardiac output, heart rate and plasma volume. A benign systolic ejection murmur caused by increased blood flow across pulmonary and aortic valves require no treatment. Pregnant patients are also susceptible to postural hypotension as a result of vasomotor instability [7]. In GIT there is decrease in lower esophageal tone along with gastric and intestinal motility due to reduced progesterone levels. Gag reflex is exacerbated.

Displacement of stomach with consequent increase in uterine size results in increased intragastric pressure. Nausea, vomiting and ptyalism are also common [7]. Respiratory signs include displacement of diaphragm superiorly resulting in decreased functional reserve capacity. Hyperventilation along with increased risk of apnea and dyspnea occur [7]. Different stages of pregnancy can cause physiologic hematological changes. During pregnancy the blood volume increases by 1.5L in order to meet the demands of the new vascular bed and to compensate for blood loss during delivery [8]. The physiologic stress induced by the pregnant state causes leukocytosis [9]. The general changes include mood and behavioral abnormalities are very common in pregnancy. There are also increased nutritional demands to meet the requirements of both mother and fetus.

Common dental problems in pregnancy and their management
Dental caries
Pregnant women are always prone to higher incidence of dental caries.Recurrent vomiting during pregnancy enhances acidic environment leading to progress of caries [10 ]. Some expectant mothers also have craving for sugary diet and also show low attention to oral health. If dental lesions are left untreated it can lead to problems like dento-alveolar abscess and cellulitis [11]. In early caries, restorative treatment is done. Amalgam is the choice in posterior teeth as there is no evidence to show that amalgam exposure during pregnancy has deleterious effects such as spontaneous abortion and child birth [12]. Composite restorations are useful for anterior teeth and glass ionomer for small restorations [13]. Endodontic treatment can be done during pregnancy in case of serious pulpal pain following odontogenic infection and the ideal time is the second trimester [14].

Gingivitis
Gingivitis is the most common oral disease in pregnancy. An alteration in oral flora, decreased immune response and increase in estrogen and progesterone levels can lead to gingivitis during pregnancy [15]. Scaling, daily tooth brushing with fluoridated tooth paste, flossing and saline mouth rinses should be used. Chlorhexidine mouth rinses have additional benefit [16].

Periodontitis
Destructive inflammation of periodontal tissue is often followed by bacterial infiltration into periodontal fibers. Periodontal pocket is formed by inflammatory response stimulated by toxins released by infiltrated bacteria which leads to tooth mobility. Cytokines, prostaglandins and interleukins are elevated in pregnancy [17]. An association between periodontitis during pregnancy and low birth weight (LBW) and very low birth weight (VLBW), pre-eclampsia and gestational diabetes mellitus have been shown in several studies [18]. Studies have shown that scaling and root planning are safe during pregnancy. 0.2% chlorhexidine mouth rinses are useful [19].

Pregnancy Tumor
Pregnancy tumor or pregnancy granuloma or pyogenic granuloma is mainly due to a combination of high progesterone levels, bacteria and local irritants, mainly calculus. It appears as a smooth lobulated mass. Gingiva is the commonest site followed by tongue, palate and buccal mucosa [20]. Pyogenic granulomas usually regress post-delivery. Excision is done only if there is problem of mastication. Excision during pregnancy often leads to recurrence and hence best avoided [21].

Tooth Mobility
Increased estrogen and progesterone levels affect the periodontal ligament leading to tooth mobility. It is usually transient and returns to normalcy post-partum [22].

Tooth Erosion
Hyperemesis during pregnancy can lead to tooth erosion. Palatal surface of maxillary incisors and canines are mostly affected and presents as sensitivity. Regular fluoride rinse and bicarbonate rinse for acid neutralization are useful [23].

Pharmacodynamics in Pregnancy
Anatomic and physiological changes in pregnancy affect the absorption, distribution, metabolism and elimination of different therapeutic agents [24]. During pregnancy, there is a high volume of drug distribution, decline in maximum plasma concentration, shortened plasma half-life, rise in lipid solubility and rate of clearance. These factors lead to drugs crossing the placental barrier leading to low fetal birth weight, teratogenicity and miscarriage. Therefore administration of drugs in first trimester should be done with extreme caution [25].

Analgesics
Drugs used for short term to treat specific disease processes. Acetaminophen (group B) daily intake in pregnant patients should be limited to 4g/day due to risk of hepatotoxicity [26]. Ibuprofen is a category B analgesic in first and second trimester while in the third trimester it is considered a category D drug because it is associated premature closure of fetal ductus arteriosus, lower amniotic fluid level and inhibition of labor [27]. A combination of acetaminophen with codeine or oxycodone is recommended to pregnant patients. Overdose of this combination can result in neonatal respiratory depression [28].

Antibiotics and Antimicrobials
Tetracycline and its derivatives like doxycycline belong to category D because of its effects on developing bone and teeth [29]. Ciprofloxacin and other quinolones belong to category C and the drug is involved in arthropathy with severe effects on evolving cartilages [30]. Metronidazole, a group B drug is not used in the first trimester because of its teratogenicity but some recent studies suggest otherwise [31]. Erythromycin estolate and other macrolides should be avoided because of deleterious effect on mother's liver [32]. The risk benefit ratio should be evaluated and obstetrician consultation is required before prescribing any antibiotics.

Local and General Anesthetics
Local anesthetics are considered to be relatively safe in pregnancy. Lidocaine and Prilocaine are category B drugs while Bupivacaine, Artricaine, Mepivacaine and Epinephrine are category C drugs. Epinephrine in intravascular route can theoretically cause insufficient uroplacental blood flow but in practice, 1:100000 concentrations used in dentistry is considered safe [33]. Nitrous oxide commonly used for surgical procedures is reported to cause abortions, preterm birth and birth defects as it is known to affect Vitamin B12 metabolism rendering the enzyme methionie synthetase inactive which is vital for DNA production and hence affects organogenesis. After first trimester short term administration of nitrous oxide with minimal concentration if 50% oxygen is considered safe [34].

Teratogenicity
Teratogen is an agent or factor that cause malformation of an embryo. Alcohol, cocaine, Thalidomide, anticonvulsants, ACE inhibitors, Retinoids, Phenytoin and Valproic acid are some of the accepted teratogens. These drugs should be completely avoided in first trimester of pregnancy [35].

Dental Radiations and Pregnancy
Dental radiography is usually considered safe in pregnancy. Radiation exposure over 10 rads is considered hazardous as it can contribute to mutation, mental retardation and ophthalmic problems. Since the fetus receives only 0.01 rads during a maternal dental radiography it is unlikely to cause significant abnormalities. Experts however advice to avoid dental radiography during pregnancy. In case of absolute necessity, precautions like thyroid collar, lead apron and speed films should be used [36].

Management Protocols during Pregnancy
The patient should be educated for changes in oral mucosa during pregnancy. The first trimester is the period of organogenesis when the patient is susceptible to teratogenicity and spontaneous abortions. Radiographs should be avoided and patient should be instructed to maintain good oral hygiene. Periodontal prophylaxis and emergency treatment can be done at this stage [37]. The second trimester is an ideal time to perform dental treatment. Elective treatments like endodontics, restorations, extraction, scaling, polishing and curettage can be done [37]. In the third trimester risk of fetus is negligible but the mother has an increased risk of discomfort. The middle of third trimester is ideal for treatment. Elective procedures as well as scaling, polishing and curettage can be done at this stage. Oral hygiene and plaque control are important [37].

Dental Chair Positioning During Pregnancy
The supine position should be avoided as it can lead to supine hypotensive syndrome. It causes a decrease in cardiac output resulting in hypotension, syncope and uteroplacental perfusion. Supine position may cause decrease in arterial oxygen tension and increase the incidence of dyspepsia from gastroesophageal reflux secondary to incompetent lower esophageal sphincter. Supine position causes compression of inferior vena cava leading to venous stasis and clot formation [38]. The patient should be positioned in the chair with the right hip elevated 10-12 centimeters so that pressure on the vena cava is reduced by placing the patient in a 5-15% tilt on left side. In case if hypotension persists, patient should be kept in left lateral position [39].

Patient Counselling
The main goal is to create awareness among the expectant mothers. Procedures like restorations and oral prophylaxis decrease the microorganisms in the mother’s mouth thereby reducing transmission to the child. Improving the expectant mother’s oral hygiene and dietary habits can have a significant impact on child's oral health [40].

Anticipatory Guidance [41]
It is the process of providing practical, developmentally appropriate information of child's health to the parents. Recommendations include;

1. Educate patient about oral disease and its prevention with demonstration of oral hygiene can be done to improve patient’s attitude and motivation
2. Eating healthy foods containing proteins and vitamins like fresh fruits vegetables and dairy products. Limit sugar consumption and avoid smoking.
3. Brushing thrice daily with fluoridated tooth paste and rinsing oral cavity with alcohol free mouth wash before bed.

Maternal Oral Health and Pregnancy Outcome
In a case-control study of 124 pregnant women, Offenbacher and colleagues in 1996 had found out a potential association between maternal periodontitis and delivery of low birthweight/preterm infants. They observed that in women who had significantly worse periodontal disease delivered at <37 weeks of gestation or an infant <2.5 kg compared to the control women. The odds ratio of the study was ∼7; led the authors to conclude that periodontitis may represent clinically significant risk factor for delivery of a preterm low birth weight infant [42]. They measured levels of PGE2 and IL-1ß in gingival crevicular fluid of 48 mothers who delivered preterm, low birth weight infants and compared it to control women and found out that levels of PGE2 were significantly higher in cases compared to control women [43].

The existing data support the role of maternal periodontitis as a potential risk factor for adverse outcomes of pregnancy such as preterm birth. Further studies to better understand the mechanism of periodontitis associated preterm birth will enable us to tailor treatment to those women who might be mostly benefited. Optimal oral health is very important for dental patient and should be administered safely and effectively. Drug administration, treatment of oral infections, radiation exposure, chair side procedures, timing of dental appointments are all important aspects to be considered while providing dental care to a pregnant lady. To improve oral and systemic health outcomes to mothers and newborns, an interdisciplinary co-operation between health professionals should be given priority.