Group+8

//E//Group 8 Members: Vivian & Emma e-Facilitator: Sophie __**PREGNANCY**__ // (Home & Family network, 2009) //


 * Learning outcomes:**
 * Understanding the physiological changes of each trimester
 * The influence of hormones during pregnancy
 * The affects hormones have on periodontal and gingival health
 * What dental procedures are recommended during pregnancy
 * What dental procedures are __not__ recommended during pregnancy

__​CONTENTS__
** Introduction

The different trimesters ** First Trimester

Second Trimester

Third Trimester

Hormones during pregnancy ** The affect of pregnancy on oral health tissues ** Gingivitis

Gingival enlargement/pregnancy tumours

Calcium levels

Morning sickness and Gastric Reflux

Food Cravings

Gestational Diabetes

Recent studies associating periodontal disease during pregnancy with premature births

 Conclusion
 * Dental procedures

References **

**Introduction** Pregnancy is a naturally occurring process that has been simply defined as ‘the events that occur from the period of conception through to birth’ (marieb & Hoehn, 2007). There are significant events that need to occur in order for this process to commence, such as conception, but the area of interest will be based predominantly around what happens during the 9 month period following conception. Pregnancy is a lengthy process that has been broken down into three stages, known as the first, second and third trimesters, which will be addressed further. The physiological changes endured during pregnancy are not only significant to the growing fetus but also to the mother, as she has to endure the imbalance of hormonal influences. These influences can present in many ways from the positive, such as glowing skin, to the negative, such as inflammation of the gingival tissues (Steinberg, 2000). The issues that will be discussed in this presentation are the influences of hormones during the different trimesters as well as their influence on the oral health tissues of pregnant women. The negative outcomes will be discussed, including the different gingival diseases that can occur and how physiological repercussions, such as morning sickness, can damage the oral health tissues. In line with this topic the influences of dental procedures will also be discussed in relation to the theories of pregnant patients and relevant health professionals as to whether procedures can or cannot be used during this time. This presentation will begin with the understanding of the different trimesters and when specific hormones are introduced.

**1) The different trimesters ** Also known as period of gestation (Wilkins 2005), pregnancy is divided into three periods called trimesters where each trimester consists of three months called the first, second and third trimester (see Figure 1.1).

**First Trimester**

The first trimester of pregnancy is known to extend from the point of initial cellular development (from conception) through to the third month (Martini, 2001) (see Figure 1.2). This period is quite critical in the embryo's development as all the organ systems are being developed and it is by twelve weeks that the embryo is able to move and swallow as the oral cavity begins to develop (Wilkins, 2005). The first development phase of the oral cavity includes the teeth, whereby tooth buds are already developing by the fifth and sixth week of gestation (Wilkins, 2005). For the mother, although not a lot of the expected physical features are yet apparent, inside the pelvic cavity the uterus occupies most of the space and tends to extend further up into the abdominal cavity as it grows (Martini, 2001). Unfortunately, during this period if infections, poor maternal health and nutrition, or harmful drug taking occurs there is an increased risk of injuries or malformations occurring during embryo development, making the embryo highly susceptible to birth defects (Wilkins, 2005). Towards the fourth and fifth month, initial mineralisation occurs. Following this, the lips are formed in the fourth to seventh week and the palate between the eighth and twelfth week. Cleft lips are apparent by the eighth week as well as a cleft palate by the twelfth week (Wilkins 2005).

It is during this three month period that a number of 'complex developmental events' occur, which have been broken down into four general processes, including 'cleavage', 'implantation', 'placentation', and 'embryogenesis' (Martini, 2001, p1068).


 * 'Cleavage' involves the process of cell divisions that are initiated immediately after the egg is fertilized by the sperm and ends at the first contact of the uterine wall (Martini, 2001). It is during this period that the 'zygote becomes a pre-embryo', which eventually becomes a multicellular compound known as a blastocyst (a spherical layer of cells that has an inner cell mass, a cavity and an outter layer/trophoblast) (Martini, 2001, p1068).
 * 'Implantation' involves the blastocyst attaching to the endometrium (lining) of the uterus and moving through into the maternal tissues where 'vital embryonic structural' events take place (Martini, 2001, p1068).
 * <span style="font-family: Arial,Helvetica,sans-serif;">'Placentation' is a very important stage where the placenta (a complex organ) starts developing as blood vessels start to form around the external surface of the blastocyst (Martini, 2001). This important organ is vital because during the second and third trimesters it supports the fetus by providing nourishment and excess waste removal (Martini, 2001). Prior to this, the 'Yolk sac' is resonsible for providing the embryo its necessary nutrients until the placental development is complete (Bath-Balogh et al, 2006).
 * <span style="font-family: Arial,Helvetica,sans-serif;">'Embryogenesis' is the stage where the embryo formation occurs (Martini, 2001).


 * Second Trimester**

The second trimester is thought to start from around the end of the third month through to the sixth month of pregnancy (Martini, 2001). It is by this stage that the development of the fetal organs and associated systems are nearly completed and the fetus shape starts to change into a more distinctive human shape (Martini, 2001). The fetus will undertake a significant increase in size during this period; growing faster than the placenta (Martini, 2001). The amniochorionic membrane (protective sac that eventually fills with amniotic fluid to support the growing fetus) is created during this period through the fusion of the amnion mesoderm (inner part of membranous sac containing the fetus) and the chorion mesoderm (outer part of membranous sac containing the fetus) (Martini, 2001).


 * Third Trimester**

The third trimester is thought to start from approximately the sixth month through to birth (Martini, 2001). The completion of organs, growth and maturation continues in the second and third trimesters with fetal weight changing on average from one ounce at three months to roughly 7.5 pounds at birth (Wilkins 2005). The growth rate of the fetus is quite rapid and it has been noted that even if the infant is premature by 1-2 months that there is still a good chance that the infant will survive (Martini, 2001). At this point of the pregnancy the uterus is seen as nearly filling the entire abdominal cavity, which pushes on the internal organs (e.g. intestines, stomach, liver, diaphragm) and widens the thoracic cavity (Grabowski & Tortora, 2003). The pressure of this large mass does take its toll on the mothers' normal bodily functions, such as the urgency to urinate as the ureters and urinary bladder are compressed (Grabowski & Tortora, 2003).

Figure 1.1 is a visual representation of the periods of prenatal development.This image starts from when the egg is fertilized by the sperm in the first week (Zygote) through till the maturation of the fetus in the final trimester.



<span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 9pt; text-align: right;">(Figure 1.2 Source: Bath-Balogh & Fehrenbach, 2006)

Figure 1.2 is a visual representation of the stages of fetal development during the early stages of pregnancy (up until 60 days/2 months). It can be seen that remarkable definition has occurred in such a short period as the fetus has not yet reached the second trimester.

<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: right;">//(Figure 1.1 Source: Hall, 2004)//

<span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;">During this nine-month process the mother experiences a number of physiological changes to compensate for the additional workload. The first obvious sign is that of weight gain, which is mostly due to the growing fetus, amniotic fluid, the developing placenta, uterine enlargement, and an increase in the bodies water mass (Grabowski & Tortora, 2003). This weight gain may also be associated with the increase in mass of the muscle fibres in the myometrium (muscle layer of the wall of uterus) (Grabowski & Tortora, 2003). Unfortunately, with this sudden and progressive weight gain the mother may also experience periods of low self-esteem, which may ultimately lead to depression. There is also a significant increase in the mothers' breast size to prepare for lactation, nipple sensitivity, and lower back pain (swayback) due to the extra weight brought on by the growing fetus (Grabowski & Tortora, 2003). The mothers' pulmonary function is progressively altered to compensate for the needs of the fetus, such as the 'total body oxygen consumption' increasing by approximately 10-20% (Grabowski & Tortora, 2003, p1088). There are numerous symptoms that could be experienced by the expecting mother, some of which include: Which are all generally associated with a decrease in the processing of contents in the GI tract. Other associated pregnancy changes can also include:
 * Constipation
 * Nausea
 * Vomiting
 * Heartburn
 * Skin pigmentation around particular areas (i.e. the eyes and cheeks)
 * Areolae (ring of colour) forming around the nipples of the breasts
 * Stretch marks over the abdomen associated with the rapid growth of the fetus
 * Increased renal functioning to compensate for the additional excrement produced by the fetus
 * Potential increase in hair loss
 * Increased flexibility and vascularity of the vagina


 * Hormones during pregnancy**

During this period of gestation there are a number of significantly important hormones released in order to safely bring the pregnancy to term. The first two are progesterone and oestrogens, which is 'two primary steroid hormones produced in the ovarian follicles under the influence of the gonadoatrophic hormones of the anterior pituitary' (Whitaker et al, 1994, p758). They are secreted during the first few months of pregnancy by the corpus luteum in the ovary as a way to preserve the lining of the uterus for the duration of the pregnancy, while also setting up the necessary mammary glands for milk secretion (Tortora & Grabowski, 2003). It is from the third month right through till birth that the placenta is then in charge of supplying these hormones, as the corpus luteum is no longer needed. Oestrogen plays an important role in the promotion of cell growth and the development of secondary sexual characteristics of women; where as progesterone's main role is almost entirely involved in preparing the uterus for pregnancy and the breasts for lactation (Whitaker et al, 1994). The levels of oestrogen in a female are secreted in small amounts during childhood and increase significantly after puberty, thereby promoting the enlargement of the external genitalia, the fallopian tubes, uterus, and vagina. Similarly, fat deposits in the breast region increase, the skin becomes more vascular and there is an increase in skeletal osteoblastic activity results (Whitaker et al, 1994). Progesterone on the other hand promotes secretory changes in the endometrium of the uterus, hence preparing it for implantation of the fertilized ovum (Whitaker et al, 1994). This important hormone also promotes secretory changes in the mucosal lining of the fallopian tubes and 'development of lobule and alveolar fat in the breasts that cause alveolar cells to enlarge and become secretory' (Whitaker et al, 1994, p758).

Another important hormone secreted into the blood, from approximately the third month through till birth, is the ‘human chorionic gonadotropin (hCG) (Tortora & Grabowski, 2003). This particular hormone plays an important role in making sure that the progesterone and oestrogens continue to be secreted, it stops menstruation from occurring, and it helps to maintain the embryo and fetus attachment to the lining of the uterus (Tortora & Grabowski, 2003).

<span style="color: #56158e; font-family: Arial,Helvetica,sans-serif; font-size: 12pt;">**2) The affect pregnancy has on oral health tissues (e.g. hormones on perio and gingival health)**

Changes to a pregnant mother’s oral health may include gingival inflammation, gingival enlargement and enamel erosion. These occurrences are usually explained as an ‘exaggerated response of the tissues to dental biofilm’ (Wilkins 2005 p. 773). However, when measures have been taken to care for the oral tissues by controlling biofilm, adverse gingival changes are not expected. Physiological changes in the mother’s body during pregnancy can be firstly seen in the gingiva from the influences of increased circulating levels of female sex hormones (Wilkins 2005). Contributing factors may include local irritation from plaque and calculus build up, trauma or poor oral health. The affects of pregnancy on the health of the oral tissues are usually seen in the second month of pregnancy and when left untreated can prove to be harmful as gingival inflammation continues with the increase of hormone levels reaching a maximum at eight months. Symptoms will lessen after birth; however a completely healthy condition does not necessarily result. Therefore, a patient who has a change in oral health during pregnancy could continue to experience these changes even if the severity appears to lessen (Wilkins 2005).

The demands of pregnancy can lead to particular dental problems in some women. With an increase tendency to snack as well as symptoms of nausea and vomiting may cause the mother to reduce oral hygiene habits due to tiredness or tendency of bleeding on brushing (Adelaide University 2007). Although luckily with well provided oral health instruction and education these problems can be eliminated. Gingivitis __** Gingivitis is the swelling or inflammation of the gums which is experienced by a number of women during the early stages of pregnancy. Gingivitis results from irritation of the gingiva due to plaque build up with clinical symptoms of swelling, tenderness, redness, sensitivity and bleeding as seen in **figure 1.1** shown below. As the human body undergoes hormonal changes (during pregnancy) the natural response of inflammation is altered and therefore becomes an exaggerated response. Hence, this condition can be easily avoided if good oral care routines are in use. Elevated levels of estrogen and progesterone during pregnancy have been the assumed cause to such an exaggerated response with the risk of developing gingivitis beginning with the second month of pregnancy and decreases with the ninth month (Katz 2009). Problems will prove to become worse if the mother has gingivitis before her pregnancy as the likelihood of the condition will become worse during pregnancy if no treatment is taken to improve health of the oral tissues. It is important to understand that it is the hormonal changes occurring in the body which results in this exaggerated response, however it is still the bacteria present in plaque that causes the initial infection and therefore inflammation (Katz 2009). If gingivitis is left untreated, this can potentially lead to periodontal disease – an infection of the gums which can cause ligaments, gums and bone surrounding the teeth to become diseased and thereby create pockets (Katz 2009). These pockets can therefore become a way in which bacteria and toxic wastes (from bacteria metabolism) enter and travel through the bloodstream. This is a significant problem which is further discussed in the section ‘Associating periodontal disease during pregnancy with premature births’.
 * __

‘The term pregnancy tumour has been used for many years to describe a lesion histologically indistinguishable ... but occurring on the gingival mucosa of a pregnant woman’ (Whitaker SB et al. 1994). Pregnancy tumours are not cancerous and are part of ‘the exaggerated response to plaque/bacteria that causes gum disease’ (Katz 2009). These ‘tumours’ are benign growths and a result of inflammatory responses which develop on the gums possibly triggered by fluctuating levels of estrogen and progesterone levels in the body (Whitaker SB et al. 1994). These lesions usually appear near the gingival margin in the interdental region with a mushroom-like shape. These lesions are usually painless unless it becomes large enough to interfere with occlusion and mastication thus can lead to inadequate nutritive intake for the mother and the baby due to discomfort while chewing (Wilkins 2005). Treatment of these lesions are necessary as it may provide a site for bacterial growth which can potentially lead to periodontal disease as well as bleeding and pain from daily brushing routine which can lead to a tendency to stop brushing (Wilkins 2005).
 * __ Gingival enlargement/pregnancy tumour __**

It is often said that when one falls pregnant, for each baby that is given birth to, the mother will lose a tooth. Fortunately, this is only a myth. Although it is true that calcium is essential for the growth of the unborn baby, calcium is supplied by the mother’s bones – not her teeth when there has been an inadequate intake of calcium during pregnancy (Better Health Channel 2009). Calcium levels are replenished through diet and quickly after breastfeeding has ceased. Thus, sufficient calcium levels will prevent a decrease in bone mass and will therefore meet the nutritional needs for the developing baby. Sources low fat dietary calcium products include milk, cheese, yoghurt, and calcium-fortified soymilk. Also, it has been shown that vitamin D helps the body utilise calcium found in cheese, margarine, salmon and eggs. Good levels of calcium are healthy for both the mother and child. Morning sickness and Gastric reflux __** As the name suggest, morning sickness occurs most commonly during the morning, but can strike at anytime of the day or night with symptoms of nausea and vomiting (gastric reflux). Despite numerous researches, the cause of morning sickness is still unknown, however theories include the cause is from hormonal changes and fluctuations in blood pressure during gestation. Statistics have shown that ‘around half to two thirds of all pregnant women will experience morning sickness to some degree’ (Better Health Channel 2009). Symptoms (nausea and vomiting) are particularly seen in the first trimester. However, morning sickness can begin around the fourth week of pregnancy and resolve around the twelfth week for some women. Also, ‘one in five women endures morning sickness into their second trimester, and an unfortunate few experience nausea and vomiting for the entire duration of their pregnancy’ (Better Health Channel 2009). Hormones which circulate the body during pregnancy can cause the ring of muscle around the entry to the stomach to soften. Hence, the damaging effects of morning sickness on teeth result from the exposure of acids due to vomiting and gastric reflux. Therefore, it is important that brushing immediately after acid exposure is avoided in order to help protect the enamel surface from erosion. Instead, smearing a small amount of fluoridated toothpaste over the teeth, rinse with water is recommended or use a fluoridated mouth rinse (Australian Dental Association 2005). Prolonged vomiting can thereby have an increased risk on caries progression with statistics showing nausea and vomiting have been recorded in 70% of pregnant women (Adelaide University 2007). Gastric reflux contains acids with low pH levels into direct contact with teeth. While good salivary flow may buffer these acids – ‘prolonged contact, particularly with incipient enamel lesions, will quickly dissolve the fragile surface causing progression of the lesion from non-cavitated to cavitated’ (Adelaide University 2007 p.1). Wilkins (2005) recommends eating small amounts of nutritious yet non-cariogenic foods throughout the day. Use sodium bicarbonate rinse after vomiting to neutralize the acid as well as chewing sugarless gum after eating especially gum which contain xylitol. As well as this, using a gentle toothbrush and low abrasive fluoride toothpaste will help in preventing further damage to demineralised tooth surfaces. Food Cravings __** Food cravings during pregnancy can lead to snacking, hence avoiding and moderating the amount of high sugar snacks is important to reduce caries risk. Foods with high calcium content are recommended such as dairy products as well as fluoridated tap water whenever possible (Australian Dental Association 2005). If low sugary foods do not satisfy the cravings, choose fresh fruits as a substitute and have water or brush after consumption (Better Health Channel 2009). Gestational Diabetes __** Gestational diabetes is specific and only occurs during pregnancy. However, after experiencing gestational diabetes, some women are susceptible to developing type II diabetes after birth (Adelaide University 2007). Although some symptoms are not always obvious, these include urination, excessive thirst, fatigue or thrush infections. “Diabetes mellitus is a chronic endocrine disorder affecting carbohydrate, fat and protein metabolism. It is caused by inherited and/or acquired deficiency in production of insulin by the pancreas, or by the reduced effectiveness of the insulin produced. Such a deficiency results in increased concentrations of glucose in the blood, which in turn damage many of the body’s systems, in particular the blood vessels and nerves (WHO 2002)” (Adelaide University 2007).
 * __ Calcium levels __**
 * __
 * __
 * __

Thus gestational diabetes is a temporary form of diabetes and usually disappears after the birth of the child. It is usually detected in the 24th – 28th week of pregnancy with statistics showing that 8% of pregnant women will develop gestational diabetes. The cause of diabetes during gestation is from the impairment of insulin action from hormones produced by the placenta needed to help the baby grow and develop, referred to as ‘insulin resistance’. Thus when energy levels increase and the role of insulin have been impaired, blood sugar levels rise and result in gestational diabetes (Better Health Channel 2009). After birth, the need for insulin returns to normal and the diabetes usually disappears. Gestational diabetes only poses a threat to the mother and unborn child if it is not diagnosed and thus not well controlled. Uncontrolled diabetes can lead to an increase risk of gingivitis and periodontitis (seen in **figure 1.2**). Although the baby will not be born with diabetes, the high levels of glucose allowed to cross over from the mother to the baby through the placenta causes the production of insulin in the baby which promotes excessive growth and fat. Hence, the baby will be born larger than normal (Better Health Channel 2009). Ways in which this could be managed to reduce any health risks include diet, physical activity, monitoring blood glucose levels and insulin injections (Better Health Channel 2009). Women who run a risk of having type II diabetes post pregnancy need to look into maintaining a healthy eating plan, a healthy weight as well as engage in physical activity and an annual oral glucose tolerance test (Better Health Channel 2009).

=Recent studies associating Periodontal disease during pregnancy with premature births= Studies indicate that the statistics for unknown causes of preterm deliveries is approximately 50%. The relationship between maternal infections and preterm labor, preterm delivery and premature rupture of membranes is being increasingly supported through research and reliable evidence (Lopez, Silva D, Ipinza, Gurtlerrez 2005). There has been numbers of recent studies which deduce that periodontal infections may be among the maternal infections which are associated with adverse pregnancy outcomes such as preterm births (Lopez, Silva D, Ipinza, Gurtlerrez 2005). Trial tests have been carried out to obtain evidence to support this claim where ‘intervention studies have demonstrated a significant reduction of preterm births and low birth weight infants in women with chronic periodontitis who received periodontal theory pre-partum, compared to women who did not receive periodontal intervention’ (Lopez, Silva D, Ipinza, Gurtlerrez p. 2145 2005). Thus; from these tests, strong evidence shows that periodontitis is a risk factor for preterm/low birth weight babies and hence periodontal therapy may reduce these risks (Lopez, Silva D, Ipinza, Gurtlerrez 2005). Bacteremia commonly occurs in patients with periodontitis as well as in those with gingival inflammation. Bacteria and their products can therefore enter the bloodstream and reach the placental tissues which provide the inflammatory effect for labour induction (Lopez, Silva D, Ipinza, Gurtlerrez 2005). The entry of these bacteria and their products trigger the production of prostaglandins, which is a natural fatty acid that normal controls inflammation and smooth muscle contraction (Katz 2009). The levels of prostaglandins in a pregnant women increases and peaks when she goes into labour, therefore with an increase of prostaglandins during an inflammatory reaction due to gingivitis or periodontitis will most likely cause the body to go into labour sooner than expected (Katz 2009). Elevated levels of prostaglandins before labour can cause premature births or births of low weight babies (Katz 2009). The study conducted by Lopez, Silva D, Ipinza, Gurtlerrez (2005) showed that pregnant women in the control group appeared to have a higher risk factor for preterm/low birth weight (PT/LBW) than women in the treatment group. However due to a reoccurrence of PT/LBW in both groups of pregnant women, it was also discovered that the presence of some conditions in the mother is a contributing factor which can make her more susceptible to the effects of infection and inflammation. ‘Hence, the success of periodontal treatment in reducing the risk of preterm birth in women with a history of PT/LBW supports the hypothesis that these women may have greater susceptibility to the effect of periodontal infection’ (Lopez, Silva D, Ipinza, Gurtlerrez p. 2150 2005). The association between periodontal disease (as well as other contributing factors and genetics), periodontal disease being the most preventable cause of preterm births indicate the importance of oral hygiene before and throughout pregnancy (Lopez, Silva D, Ipinza, Gurtlerrez 2005). It is essential that mothers are educated and motivated to maintain a high level of oral hygiene and that treatment is administered as soon as possible if periodontal infection is diagnosed at anytime. Not only is optimal oral hygiene beneficial to the mother and the health of the baby, premature deaths and biological, social and economic impairment will be reduced (Lopez, Silva D, Ipinza, Gurtlerrez 2005).


 * <span style="color: #097b09; font-family: Arial,Helvetica,sans-serif; font-size: 12pt;">3) What dental procedures are allowed to be used during pregnancy **

Many studies have been conducted in relevance to dental procedures and how they can affect the natural cycle of pregnancy. One study, conducted within Ohio (USA) between 2004-2005, was based on a survey distributed in order to gain the perceptions of a number of pregnant patients, dentists and Obstetricians about 'dental care during pregnancy (Stafford et al, 2008). It was found that the most common treatments received during pregnancy were cleans and fillings, while the most withheld treatment was x-rays (Strafford et al, 2008). These results were based on the personal preferences of the patients, although it was found in this study that approximately 10% of patients were refused treatment by dentists (Stafford et al, 2008).

In regards to the perceptions of the Dentists and Obstetricians of this study, it was found that there were some mutual agreement but also significant differences with the safety of particular dental treatments. Obstetricians and dentists in this study both believe that pregnant patients are capable of undergoing dental cleans, caries treatments, roots canals and abscess drainages (Strafford et al, 2008). There were a few treatments that were not mutually agreed upon as 'safe' during pregnancy, such as X-rays, amalgam placement, sealants, extractions, medication usage and periodontal surgery (Strafford etc, 2008). The perception percentages varied in relation to different treatments, such as X-rays, extractions and nitrous oxide. It appears that a high percentage (92%) of Obstetricians believed that with proper use of shielding that x-rays could be taken with pregnant women; extractions are another procedure thought to be highly possible by both dentists (79%) and obstetricians (92%); and the use of nitrous oxide is a product that only a small percentage (10%)of dentists agree can be used while pregnant (Strafford et al, 2008).

X-rays are a diagnostic tool that is always under constant debate in regards to when they should be taken with pregnant patients. Regulations have been set out for the use of dental radiographs indicating that the operator should enquire as to whether the female patient (of childbearing age) is pregnant or could be pregnant (Whaites, 2003). If their patient is pregnant there are a number of factors that need to be considered, such as are the reasons for requiring an x-ray justified or could they be delayed; is the patient aware of their right to delay the radiograph/s and that a 'minimal dose is being employed' when they are used; and whether a protective lead apron needs to be used for necessary occlusal x-rays (Whaites, 2003). These regulations and conditions are necessary to protect the developing fetus and the patient from the dangers of ionising radiation. It is during this vital developmental stage, particularly between 2-9 weeks, that organogenesis is occurring and ionising radiation could be potentially harmful, it is also at this stage that the female may not be aware that they are pregnant (Whaites, 2003). Apart from radiographs there have been concerns surrounding whether extractions are an allowable procedure for expectant mothers. Many studies, surrounding this issue, have found that there is a conservative use of such dental treatments during pregnancy, not only by the expecting mothers but also as recommended by the dental practitioners (Jiang et al, 2008). The two main issues surrounding the use of extractions appear to be based around 'when' it should be done and the effects of the associated anaesthetic/prescribed medications. As was mentioned previously, the first three months of fetal development is critical and it is apparent, in relevant studies, that there is a consensus to this fact, as such treatments, like extractions, are seen as safer after this period (Jiang et al, 2008). It has been recommended that any treatment done during pregnancy should be aimed as 'controlling disease', 'maintaining a healthy oral environment', and 'preventing potential future problems' (Giglio et al, 2009, p45). Jiang et al (2008)'s article strongly suggests that treatments, such as extractions, have been recommended to be left until after the birth, unless circumstances, such as pain, deem the circumstance otherwise. This also includes reasons based on patient positioning and discomfort in the last few months of pregnancy, which will be mentioned later.

Fluoride is an approved treatment to help pregnant patients to relieve their sensitivity and assist in remineralising the damaged enamel caused by nausea and vomiting (Giglio, 2009). It has been recommended, however, that certain kinds of topical fluoride not be used as it may cause nausea, such as fluoride gel, while fluoride varnish maybe more tolerable (Giglio, 2009).

​ The following table is a summary of the different therapeutic drugs that are used or prescribed by dental practitioners and their potentially negative influences on a pregnancy outcome.
 * Medications and Anaesthetics**

//(Moore, 1998, p1283)// The prescribing and administration of drugs is a necessary part in dental treatment, when required, to assist in pain relief, infection control and anxiety relief. The general concern about the use of drugs during pregnancy is the risk that it will cross the placental barrier and cause detrimental affects on the development of the fetus (Giglio, 2009).

Local anaesthetics are generally considered safe as long as they are administered appropriately and at the correct dosage. Certain drugs are categorized as more risky, particularly adrenaline based anaesthetics, as it has been theorised that it can cause an 'insufficiency of uteroplacental blood flow' (Giglio, 2009, p47). It has been concluded, however, that within the dentistry field that if anaesthetics are given adequately then it is considered safe (Giglio, 2009).

Analgesics are generally used for managing pain and anxiety, which have potential risks, such as liver toxicity, which is why a recommended maximum dose is instructed for daily use (Giglio, 2009). The safest analgesic mentioned is 'acetaminophen', while one risky analgesic mentioned is 'Ibuprofen', which has been said to be reasonably safe in the first two trimesters but potentially risky in the third trimester due to associated side effects, such as causing premature closure of fetal ductus arteriosus and lowering levels of amniotic fluid (Giglio, 2009).

Antibiotics prescribed by dentists can have varying effects on both the mother and fetus. There are particular antibiotics that have been classed as potentially harmful, such as tetracycline that can potentially effect development, teeth and bone of the fetus (Giglio, 2009).

Finally, in regards to sedatives, there have been a number of drugs that have been advised to be avoided during pregnancy, such as 'benzodiazepines' because of implications such as the development of cleft lip and palate (Giglio, 2009). Nitrous oxide is a well-known sedative used in the dental field, to relieve pain and anxiety, but there has been debate about potential side effects (Mennito, 2006). The potential side effects mentioned include the potential to be teratogenic (cause of birth defects), there is a higher risk of miscarriage, and the potential for hypoxia (Minnito, 2006). It has been emphasized that informed consent should be obtained from the patient, that the patients obstetrician has also approved the use of this sedation, that it be used after the first trimester, and that a minimal concentration of 50% oxygen be used with administration of the nitrous to be safe (minnito, 2006).


 * Patient positioning**

There is a significant importance placed on the positioning of a pregnant patient during treatment. It has been emphasised that when a pregnant patient is in the dental chair that they not be positioned in the full supine position, as the enlarged uterus can compress the vena cava, a condition known as Aortocaval compression (Giglio et al, 2009). This condition can lead to potential 'supine hypotensive syndrome', which has a number of signs and symptoms as an indicating factor, such as light-headedness, a decrease in blood pressure, sweating, restlessness, and in more severe circumstances unconsciousness and convulsions(Giglio et al, 2009). This has the potential to also affect the ergonomics of the dental practitioner, as they have to find an alternate means of conducting procedures away from their recommended positioning. When the patient is to be let up from the chair it has been recommended that they be let up very slowly, in order to prevent postural hypotension (Giglio et al, 2009). This condition is also a result of the growing uterus as it induces pressure on the vena cava and aorta resulting in 'decreases in cardiac output, venous return and uteroplacental blood flow' (Giglio et al, 2009, p43). The correct positioning recommended, to prevent the uterus squashing the vena cava, is to roll the patient on to her left side and elevate her right hip slightly through the use of a soft elevator, such as a towel or cushion (Giglio et al, 2009).

As there are numerous case studies conducted to try to prove or disprove the myths about dental treatment and pregnancy, it is in the dental chair that most of this information comes down to perception and interpretation from the people involved in the treatment. The current perceptions of the pregnant patient as she walks through the door of the dental clinic and the current perceptions of the practitioners based upon their years of experience and wisdom, their research and how they personally perceive that research. These factors are what inevitably can affect the information that comes across during a consultation about dental treatment. This technological age allows pregnant mothers to access the Internet, which provides easy access to a library of information, so they can look into dental treatments and their side effects in order to ask their dentist the right questions to validate their concerns.

=**Conclusion**=

The process of gestation (pregnancy) is an intriguing yet complex journey in regards to the various changes and restrictions imposed upon expectant mothers and their fetus. The various physiological changes associated with each trimester falls in line with the rapid growth of the fetus and the support mechanisms required assisting in that growth process. The hormones associated with this change were discussed, particularly estrogens, progesterone and hCG, in relevance to their role in preparing the uterus for pregnancy, the influence on the females sexual development, and the maintanance of these processes. These hormones were also found to be quite influential on oral health, particularly from the second month of pregnancy, as detrimental effects could occur if the mother does not place importance on her oral health maintanance. These detriments varied as their sources ranged from either poor oral health maintenance, causing potential gingivitis, through to unavoidable physiological changes, such as erosion caused by vomiting or 'morning sickness'. Some oral health diseases, such as periodontal disease, were found to pose potential health risks towards the fetus resulting in a pre-term/low weight birth, thus the importance of dental check ups and oral health maintenance had been emphasised. In relevance to this topic, the various myths surrounding dental procedures and their level of safety during pregnancy were discussed. It was found that x-rays were the most commonly debated issue among relevant health professionals (dentists & obstetricians) and with the pregnant mother as the fear of ionising radiation could affect fetal development. This issue as well as those associated with the use of particular medications, anaesthetics and antibiotics were all debated and given limitations to their use, mostly being that if the dental issue is not an emergency, or not immediately necessary, then the procedure could wait until after the birth. This recommendation was also found to be relevant to patient positioning in the chair, as the expecting mother is not able to lie in the full supine position in her later trimesters, the risk of aortocaval compression is increased, which can also pose a problem for the dental practitioner and their standard ergonomic practices. As a dental practitioner it is important to understand the different changes associated with pregnancy in order to understand why particular signs and symptoms are occurring and when safe, necessary treatment can be administered. This is to ensure the safety of the fetus and its development, while also taking care of the expecting mother and her needs.

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