Dental barotrauma has been called aerodontalgia or barodontalgia when it is applied to altitude exposure. There are three common presentations of dental barotrauma.
In the first presentation, gas spaces may exist in the roots of infected teeth, along dying nerves, in necrotic or inflammatory areas of the pulp, alongside or associated with fillings that were poorly inserted or have undergone secondary erosion, jawbone cysts, impacted teeth or other oral maxillofacial disease. The gas may enter around the edge of the filling, adjacent to the tooth or through micro-fractures of the enamel and dentine (Figure 9.1).
Teeth with full cast crowns may be susceptible to air being forced into the cemented material between the crown and the tooth – especially with a zinc phosphate cement or, to a lesser extent, glass ionomer cement. Micro-leakage of gas is not as evident with resin cement.
During descent, the contracting gas space is replaced with the soft tissue of the gum or with blood and effusion. Pain may prevent further descent. If, because of slowed descent, symptoms are not noticed, then gas expansion on ascent may be restricted by the blood in these spaces, thus resulting in distension and pain.
Divers sometimes experience dental barotrauma reliably at a certain depth, but often without the gas space able to be readily visualized on dental x-ray films. Transillumination with a high-intensity light may reveal the micro-fractures. Because of the aetiologies described earlier, the barotrauma is often encountered in older divers.
A second type of presentation of dental barotrauma occurs in cases involving a carious tooth with a cavity and very thin cementum. As pressure differences across the cementum develop, the tooth may cave in (implode) on descent or explode on ascent, causing considerable pain. Fast rates of ascent or descent will precipitate this. Pressure applied to individual teeth may cause pain and identify the affected tooth. Sensitivity to cold may also localize the tooth.
A third form of dental barotrauma involves the tracking of gas into tissues (surgical emphysema), through interruptions of the mucosa, e.g. diving after oral surgery, dental extractions or manipulations. Scuba regulators produce a positive oral pressure, forcing gas into tissues.
Preventive measures include biannual dental checks (including x-ray examinations if indicated), avoidance of all diving after dental extractions and surgery until complete tissue resolution has occurred (i.e. intact mucosal surface) and slow descent and ascent.
Treatment consists of analgesia and dental repair. The differential diagnosis of sporadic or constant pain in the upper bicuspids or the first and second molars, but not localized in one tooth, must include other dental disorders (see Chapter 42), as well as referred pain from the maxillary sinus or the maxillary nerve (see Chapter 8). This may also manifest as a burning sensation along the mucobuccal fold.