Radiographs, pregnancy and the foetus
X-rays are a type of electromagnetic radiation that have the ability to ionize the material through which it passes. Ionizing living matter results in a damage to the cells or the DNA. Depending on the amount of radiation and the stages of pregnancy, a damage to the foetal cells may result in miscarriages, birth defects or mental impairment. However the dental radiation exposure of the foetus is negligible [21]. The embryo and the foetus, being much more radiosensitive than the adult counterpart, are susceptible to adverse effects which result from the radiography exposure. During the first 2 weeks after the conception, the patient may have no knowledge of being pregnant, thus making it prudent for the physician to inquire about the last menstrual period before obtaining a radiographic image. Because a general questioning does not give a definitive diagnosis about the pregnancy status, a lead shielding should be used for all the women who are in their childbearing years. The frequency of mutations and adverse effects is directly related to the dose, and the exposure is augmented when higher than necessary radiation exposures are used to compensate for the inadequate processing quality. The exposure can also be increased, depending on the view which is taken. The radiations from the maxillary anterior views may pass through the abdominal area, with penetration from the primary beam, as well as from the scatter /radiation. Depending on the head position, a similar exposure could also occur with the posterior views [19–21]. Several precautions can be taken to avoid the foetal exposure when radiographs need to be taken. Using a lead shield over the patient’s abdomen, using a properly collimated beam, and using a high-speed film, can reduce the foetal exposure. The teratogenicity of the radiation depends on the foetal age and the dose of the radiation. The greatest risk to the foetus for teratogenicity and death, is during the first 10 days after the conception. The most critical period of the foetal development is between 4-18 weeks after the conception. The National Commission for Radiation Protective (NCRP) recommends that the cumulative foetal exposure to radiation should not exceed more than 0.20 Gy, which can cause microcephaly and mental retardation [22].