Barodontalgia: Etiology, Features and Prevention

Barodontalgia is a symptom that reflects a flare up of preexisting sub clinical oral disease. Deep sea divers, Aircrew members and passengers are at increased risk of experiencing barodontalgia due to exposure to increased air pressure. It is important for dentists to understand the etiology and features of barodontalgia in order to prevent it. This article reviews the literature regarding barodontalgia, its etiology, features, and prevention.


Introduction
During World War II, the name Aerodontalgia was given to tooth pain experienced by air crew during flight. However, as this tooth-related pain was also observed in divers, a broader, more appropriate term, Barodontalgia, was subsequently given to this phenomenon [1].
With the increase in number of air passengers, pilots, and professional and amateur self-contained underwater breathing apparatus (SCUBA) divers, dentists come across Barodontalgia as an emergency situation often in their practice [2].
Barodontalgia is pain or trauma affecting teeth due to variations in pressure gradients and commonly affects air crew and aircraft passengers as well as underwater divers [3]. In rare instances, dental pain during flying or while diving has been indicated as a potential cause of an aircrew member or a diver suddenly becoming incapacitated, thus compromising the safety of the affected person as well as others [4][5][6]. This article reviews the literature regarding Barodontalgia, its etiology, features, and prevention.
Previous reports have documented external Otitic Barotrauma (caused by expansion of air in earphone) [13] and Dental Barotrauma (Barometric pressure-related fracture of dental hard tissue and/or restoration) [14] to have caused Barodontalgia. These examples of facial [15] and dental [16] Barotrauma, respectively are unique along with Barosinusitis as Barometric-related pathologic conditions that are generated during flight from pressure changes rather than pressure-related flare-up of preexisting conditions.

Classification
Currently Barodontalgia is classified according to pulp/periapical condition and symptoms into 4 classes [17, 18] (  Pain on sinus palpation. Pain upon a sharp change in the head position.
Opacity (fluid) on the maxillary sinus image.

Barodontalgia in Divers
Scuba diving is one of the fastest growing recreational sports in the world today. Hence dentists should be aware of the possibility Barodontalgia which may arise during scuba diving and methods to diagnose and treat the same. Tissue injury might occur during ascent or during descent due to Barodontalgia [20].
Barotrauma of Descent: Barotrauma is the process in which there is a failure of an enclosed gas-filled space to adjust its internal pressure to the surrounding external pressure, resulting in tissue damage [21].The most common dental complaint experienced by divers is that of dental squeeze, also referred to as Barotrauma of descent [22]. This is due to conditions associated with exposed dentinal tubules or pulpal tissue. When the diver descends, air is forced into the pulp due to the increased pressure of the inspired air. The pain experienced is related to the diver's depth, and usually improves when the diver ascends, thereby relieving the pressure. Compressed air reaches the dentinal tubules or the pulp through Primary caries, recurrent caries along the margins of restorations, or leaking restorations [23] Pulpitis due to recent dental treatment could be another possible cause of the dental squeeze [2]. Dental treatment invariably causes a slight degree of inflammation with subsequent swelling in the pulp, resulting in a tooth sometimes being sensitive for a few days after treatment. When pressure is applied to inflamed or bruised tissues, gasses formed due to the inflammation process are compressed and increase the pressure in the pulp cavity, resulting in pain. Hence, patient should be advised not to dive shortly after having a new restoration placed, especially not a deep dive. Similarly, after tooth extraction or minor oral surgery, the inflammation should also be allowed to subside before diving, as pain and bleeding may be induced by increased pressure [24] Barotrauma of Ascent: A second type of Barodontalgia is referred to as Barotrauma of ascent and is caused by compressed air that has been trapped in an enclosed space and then expands as the diver ascends. This kind of injury is seen in teeth with incomplete root canal treatments or neglected restorations [2]. During descent, compressed air slowly enters these teeth due to a poor physical seal between the tooth and restoration, but cannot escape quickly enough during ascent [22]. As the diver's depth decreases, there is pressure build-up within the tooth due to expansion of the trapped air, leading to severe pain and sometimes even fracture. Displacement of the intra-canal medicaments through the root apex has been reported [4].In severe cases the pressure build-up in the tooth may lead to explosion of the tooth, called Odontecrexis [25].

Barodontalgia during Flight
Aircrew members have been reported to be vulnerable to several flight-induced oral pathologic conditions including Barodontalgia [6,7,25,26]. When a person reaches high altitudes in unpressurized airplane cabins, as the outside pressure decreases, the volume of the gases increases .This creates a problem in tooth chambers and canals, since the gases cannot expand or contract in a manner needed to adjust the internal pressure to match the external pressure [19].
During flying, Barodontalgia has been reported to occur across a broad range of altitudes, having been reported at altitudes as low as 5000 feet and as high as 35000 feet but is more common between 9000 and 27000 feet [1].

Prevention and Management
The Fédération dentaire internationale (FDI) has divided Barodontalgia into 4 groups from moderate to severe, and have listed out a description of clinical symptom, findings and therapy.
The treatment options for Barodontalgia are numerous, depending on the chief complaint, clinical finding and diagnosis. These treatments can range from palliative to definitive, subject to the accessibility of dental care, as some of the triggers could be in the course of activities such as flying or diving. These options have been elaborated by the FDI as in table. 3.
FDI also recommends that annual checkups be done for divers, submariners and pilots, with oral hygiene instructions from dentists. After a dental treatment requiring anesthetic or 7 days following a surgical treatment, patients should be instructed not to dive or fly in non-pressurized cabins for the next 24 hours [28]. Periodic oral and dental examinations, including periapical radiographs and vitality tests, are recommended for the prevention of Barodontalgia in high-risk populations (e.g., aircrews, divers). In addition, screening panoramic radiographs are recommended for these populations at 3-5-year intervals [19,29]. Special attention needs to be paid for periapical pathosis, faulty restorations, secondary caries lesions, and signs of teeth attrition [30,31].

Conclusions
Although rare, Barodontalgia can cause serious risk to Scuba divers, Submariners, Air crew and passengers. It is important for dentists to understand the etiology and features associated with Barodontalgia in order to help prevent it. Dentists can better tackle this phenomenon by adhering to the guidelines given by FDI. However, further research is required to completely understand the pathogenesis of Barodontalgia.