Clearing Up the Confusion about Medicare and Dentistry.

With the growing number of air passengers, flight at­ tendants, leisure pilots, as well as military and airline pilots, dentists may encounter physiological and patho­ logical phenomena precipitated by high altitude. With the introduction of the self-contained breathing appa­ ratus (SCUBA), many of these manifestations caused by changes in atmospheric pressure were reported in association with diving as well. Limited literature ex­ ists on this subject. Hence, this article aims to review literature concerning the classification, etiology and manifestations of barodontalgia, as well as important clinical considerations for its management. Barodontalgia, which affects air crew and aircraft passengers, as well as underwater divers, is pain or injury affecting teeth due to changes in pressure gradients.1 It has been reported also as a con­ sequence of air bag rupture and the high pressure air inhaled by the car driver during an accident.2 It is sustained from the failure to equalize the pressure of an air-containing cavity to that of the surrounding environment. In general, barotrauma is defined as pressure-induced dam­ age that can occur at both high and low pressures. Changes in ambient pressure, for example, during flying, diving or hyperbaric oxygen therapy, can lead to barotrauma. Flying and diving are usually associated with different types of pressure changes. Dur­ ing commercial flights, for example, aircraft personnel are ex­ posed to only minor pressure differences, but this exposure lasts for a relatively long period of time. By contrast, military and aerobatic pilots are subjected to rapid pressure changes and strong acceleration forces. As a re­ sult of the higher density of the surrounding medium, divers are exposed to very high ambient pressures. Compared with aircraft personnel, however, the duration of exposure is usually short. De­ pending upon diving depth and technique, there are considerable differences in the breathing gases used. This causes further physi­ ological and metabolic changes in the human body, in addition to changes in ambient pressure.3 Etiology Barodontalgia is a symptom rather than a pathological condition and in most cases reflects a flare-up of pre-existing oral disease; hence, most common oral pathologies have been reported as pos­ sible sources of barodontalgia.4,5,6 The chief prerequisite for toothache at high altitude is the presence of some pre-existing pathological disturbance of the pulp. The environmental changes associated with high altitudes may cause an exacerbation of symptoms. High altitude environ­ ment does not affect a normal pulp. From an analysis of more than 1,000 case histories by the army/air force dental research group,6 toothaches at altitude were grouped into the following three categories on the basis of clinical findings: Group I: Pain in teeth with irreparable damage to the pulp. Clinical findings included pulp destruction and periapical lesions. Treatment includes root canal therapy or extraction. 22 APRIL 2015 • The New York State Dental Journal The New York State Dental Journal • APRIL 2015 23 Group II: Pain in teeth with a reversible disturbance of the pulp. These could be attributed to recently done fillings, defective fillings, recurrent caries and hypersensitive dentin. They respond to restorative treatment or do not recur after a few flights. Group III: Pain referred to the teeth from aerosinusitis, ae­ rootitis, or unerupted or partially erupted third molars.6 Barodontalgia affects 11.9% of divers and 11.0% of military air crews, with a rate of 5 episodes/1,000 flight-years. Upper and lower dentitions were affected equally in flight, but more upper than lower dentitions were affected in diving. The most prevalent etiologic pathologies for in-flight dental pain were faulty dental restorations (including dental barotrauma) and dental caries without pulp involvement (29.2%), necrotic pulp/periapical in­ flammation (27.8%), vital pulp pathology (13.9%), recent dental treatment or “postoperative barodontalgia”(11.1%). Barosinus­ itis was the main cause of pain in 9.7% of the cases.4,7 Barodontalgia was most prevalent in the third decade of life and showed no gender preference Classification Barodontalgia is subgrouped into direct (dental-induced) and in­ direct (nondental-induced) pain. The currently accepted classifi­ cation of direct barodontalgia consists of four classes according to pulpal/periapical conditions and symptoms.4,8,9 Strohaver10 has advocated the differentiation of barodontal­ gia into direct and indirect types. In the direct type, reduced at­ mospheric pressure contributes to a direct effect on a given tooth. In the indirect type, dental pain is secondary to stimulation of the superior alveolar nerves by a maxillary barosinusitis. Direct barodontalgia is generally manifested by moderate-to­ severe pain, which usually develops during ascent, is well local­ ized, and the patient can frequently identify the involved tooth. Indirect barodontalgia is a dull, poorly defined pain that generally involves the posterior maxillary teeth and develops during descent. If pain occurs during descent, indirect barodontalgia attributable to barosinusitis should be suspected. If indirect barodontalgia is diagnosed, the patient should be referred to a medical practitio­ ner or an ear, nose and throat specialist for treatment.11,12 Pathology The pathology of barotrauma is directly related to Boyle’s law, which states, if temperature remains constant, the volume of a fixed mass of an ideal gas is inversely proportional to the pressure of the gas. As pressure increases, the volume of a confined gas decreases. Specifically, as a person descends deeper and deeper be­ low the water surface, pressure exerted on the diver by the water increases and reduces the volume of gases in enclosed spaces such as teeth and sinuses. TABLE 1 Classification of Direct (dental-induced) Barodontalgia4 Class Pathology Features 1. Irreversible pulpitis: Sharp transient (momentary) pain on ascent. 2. Reversible pulpitis: Dull throbbing pain on ascent. 3. Necrotic pulp: Dull throbbing pain on descent. 4. Periapical pathology: Severe persistent pain (on ascent/descent). The same law applies if a person climbs to high altitudes (in flight); in this case, outside pressure decreases, permitting the volume of gases to increase.1,14,15 Pain during ascent can indicate the presence of a disease of vital pulp tissue (pulpitis). Pain during descent can be indicative of pulp necrosis or facial barotraumas.3,15 Pathogenesis There was no published research regarding the pathogenesis of barodontalgia in the past decade. Some theories exist, but most were offered in the first half of the 20th century.4 Kollmann5 re­ fers to three important hypotheses to explain this phenomenon: expansion of trapped air bubbles under a root filling or against dentin that activates nociceptors; stimulation of nociceptors in the maxillary sinuses, with pain referred to the teeth; and stimula­ tion of nerve endings in a chronically inflamed pulp.1 He strongly supports the last two hypotheses and states, for the latter, that histologic evidence shows that chronic pulpal inflammation can still be present even when a thin dentin layer covers the pulp—for example, as in a deep cavity preparation.1 Yet the pathogenesis of this unique dental pain remains occult. Diagnosis Certain generalities have been established to help with the diag­ nosis of direct barodontalgia. Posterior teeth are more frequently involved than anterior teeth, while maxillary teeth are affected more often than mandibular teeth. Teeth with amalgam restora­ tions are more likely to be involved than unrestored teeth; and re­ cently restored teeth are particularly susceptible. Examination of a patient complaining of barodontalgia should include an estima­ tion of the age of restorations in the suspected area, exploration for caries or defective restorations, percussion of any suspected tooth, the patient’s response to the application of electrical stimulation and/or cold and heat, and radiographic examina­ tion.11,16,17 Appropriate radiographs of the suspected teeth should be obtained, with the understanding that a negative radiograph does not rule out pulpitis.16 Barodontalgia has been found to occur during diving in teeth with carious lesions, or where there are periapical lesions, periodon­ tal abscesses, maxillary sinus congestion and recently crowned teeth.