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Special Situations

Bettina Basrani

Pregnancy

Oral radiography is safe for pregnant patients provided that protective measures such as high-speed film and lead apron and a thyroid collar are used. No increase in congenital anomalies or intrauterine growth retardation has been reported for X-ray radiation exposure during pregnancy totaling less than 5–10 cGy, and a full-mouth series of dental radiographs results in only 8 × 10–4 cGy (National Council on Radiation Protection and Measurements, 2003). A bitewing and panoramic radiographic study generates about one-third the radiation exposure associated with a full-mouth series with E-speed film and a rectangular collimated beam (Freeman and Brand, 1994). Patients who are concerned about radiography during pregnancy should be reassured that in all cases requiring such imaging, the dental staff will practice the ALARA (As Low as Reasonably Achievable) principle and that only radiographs necessary for diagnosis will be obtained (Carlton et al., 2000).

The estimated fetal dose in a single dental exposure is 0.01 mrad. It is known that doses less than 5 rad are not associated with increased congenital malformations; therefore, dental X-ray scans should not be cause for concern. A UK epidemiologic study of a cohort of 7375 mothers did not find a significant association between use of dental X-ray scans and low birth weight or preterm delivery. In addition, a case-control study found no overall increased risk of childhood brain tumors after exposure to prenatal abdominal X-ray scan, which produces many times higher radiation exposure than dental X-ray scans. (Michalowicz et al., 2008)

Radiation Therapy

Patients with a malignancy in the oral cavity or perioral region often receive radiation therapy for the treatment of their disease. Although such patients are often apprehensive about receiving additional exposure, dental exposure is insignificant when compared with what they have already received.

In addition to the clinical examination, a thorough radiographic examination is crucial to determine the presence of inflammatory periapi­cal abnormalities, periodontal status, other dental disease, and tumor invasion of mandibular or maxillary bone. A panoramic radiograph plus selective periapical and/or bitewing films should be available for dental assessment previous to radiotherapy. Consultation with the patient’s physician on the timing, nature (external beam radiotherapy or radioactive implant), and features (location and size of treatment fields, radiotherapy fractionation and total dose) of the radiotherapy is essential for overall risk assessment and scheduling of any required dental intervention. (White and Pharoah, 2009)

Gag Reflexes

Gag reflexes occur in most patients as a natural reaction to tactile stimulation of the soft palate, base of the tongue and parts of the pharynx. In some patients, these reflexes are so predominant that dental procedures such as impression making, dry field maintenance, and placement of dental X-ray films intraorally are made difficult. In extreme cases, adequate examination and dental treatment of these patients may be impossible (Bassi et al., 2004).

The gag reflex is a normal defense mechanism, in preventing foreign bodies from entering the trachea. During the reflex, the shape of the pharynx and its openings are altered by spasmodic muscle contractions.

Characteristic elements of the gagging behavior have been described as follows: (1) puckering the lips or attempting to close the jaws, (2) elevating and furrowing the tongue, (3) elevation of the soft palate, (4) contraction of the anterior and posterior pillars of the fauces, (5) elevation, contraction, and retraction of the larynx and closure of the glottis, (6) forcing air through the closed glottis, producing the characteristic retching sound, (7) excessive salivation, lacrimation, and sweating, (8) respiratory muscle spasm, and (9) vomiting (Kumar et al., 2011).

The regions most sensitive to stimuli that produce the gag reflex are the fauces, base of the tongue, palate, uvula, and posterior pharyngeal wall. Sensory nerves forming afferent pathways for impulses to the reflex center in the medulla oblongata are the trigeminal, glossopharyngeal, and vagus (cranial nerves V, IX, and X). At the release of the complex muscular and secretory elements of the gag reflex, a number of cranial nerves as well as sympathetic and parasympathetic nerves participate. Gag reflexes may be initiated by psychological factors as well as by tactile stimulation. Anxiety and awareness of a previous gagging problem may heavily influence the severity of the condition.

Recommendations for suppressing and reduc­ing gag reflexes during intraoral radiographic examination

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