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The Rarest Barotrauma

by Laurence A Stein, DDS
A Miami Dentist describes an unusual case of tooth squeeze

Alert Diver September/October 1993
(Reprinted with permission of the author and DAN.)

"Barotrauma --- or, more commonly, squeeze --- of the ears and sinuses is quite likely the most common problem among divers. Another less common --- almost rare--- type of barotrauma divers sometimes suffer from is known as barodontalgia, or tooth squeeze."

   Barodontalgia can be caused by any of the following conditions: caries (decay); recurrent caries; defective margins on restorations; oral tissue lacerations; recent extractions; periodontal gum abscesses; maxillary sinus congestion; pulpal and apical lesions; cysts; and endodontic (root canal) therapy. It is even suggested that divers should wait 24 hours between dental treatments --- even fillings --- before diving. Teeth undergoing root canal procedures with temporary fillings have been known to explode when the diver surfaces. There are also reports of porcelain shattering from full porcelain-bonded crowns and the loss of gold and porcelain-to-metal crowns.

   The diagnosis of barodontalgia should be considered if a patient complains of pain during diving or flying. Clinically, patients have few if any symptoms by the time they arrive at the dentist for evaluation. Often the diagnosis is suspected but the offending tooth cannot be located --- especially if there are numerous fillings, periodontal lesions or teeth with root canal treatment underway or already completed and when there is no pain at the time of the examination and negative x-ray examination. Suspicion of the offending tooth is higher if fractured fillings or teeth are located, caries is detected either clinically or on x-ray, or if the x-ray shows pathology at the apex of the tooth. Incomplete root canal fillings are suspect --- particularly if the patient shows symptoms including percussive (pressure) sensitivity on a particular tooth and if that tooth became sensitive during or immediately following a dive.

In addition to barodontalgia, barosinusitis and temperomandibular joint disorders would also be part of a differential diagnosis. Both could have a sudden onset and refer pain to seemingly unrelated structures.

The proximity of the upper molar and bicuspid teeth to the maxillary sinus frequently causes divers to experience referred pain from the sinus applying pressure to the roots of teeth near the affected sinuses. In fact the most frequent cause of barodontalgia is associated with maxillary sinus congestion and maxillary dental pain, otherwise known as sinus squeeze.

According to U.S. Air Force findings during decompression tests, there is a 1.63 % incidence of barodontalgia in the 12,000 subjects tested. In 1943, experimental data results from decompression tests at the Naval Air Station at San Diego, California were reported, with 1.2 % incidence rate.

Teeth undergoing root canal treatment may have a soft temporary filling used to plug the opening to the nerve chamber and canals. There is frequently a small piece of cotton placed under this filling to apply medication between visits or to serve as a marker to the restorative dentist when finishing the final restoration. There is an air space created under these circumstances.

Another condition seen with teeth which have had root canals are incompletely filled canals --- which can be caused by a variety of reasons, ranging from improper technique to the anatomy of the tooth. Again, there may be a potential air space in the unfilled portion of the root. Commonly, there is a recurrent abscess of such a tooth, but it may be chronic and therefore painless under normal circumstances. X-rays may show a dark area at the root tip, which could be the infection, or in long standing circumstances, a cystic lesion.

Teeth requiring or already having root canals have the additional problem of having an inadequate or nonexistent blood circulation to the root. This complicates the ability of any potential spaces within the tooth to in-gas and off-gas at the same rate as vascularized tissues. In addition, the lack of circulation also causes the surrounding tooth structure to become more brittle and the tooth to be more subject to fracture. These fractures may exist prior to the dentist performing the root canal treatment, and the tooth may have been free of any symptoms occasionally associated with fractures. These fractures can act as rupture points along the root or allow the direct passage of gas between the tooth and surrounding structures.

Table I. Proposed System of Classification of Barodontalgia
Class 1 2 3 4
Chief Complaint Sharp, momentary pain during ascent (decompression): asymptomatic on descent (compression) and afterwards Dull, throbbing pain during ascent (decompression): asymptomatic on descent (compression) and afterwards.  Dull throbbing pain during ascent (decompression): asymptomatic on descent (compression) and afterwards. Severe, persistent pain after ascent (decompression) or descent (compression)
Clinical Findings Caries or restoration with inadequate base. Tooth is vital and x-ray shows no pathosis.  Deep caries or restoration.

Tooth is vital/nonvital. 

X-ray shows no pathosis.

Caries or restoration.

Tooth is nonvital.

X-ray shows pathosis

Caries or restoration

Tooth is nonvital.

X-ray shows definite pathosis

Diagnosis Acute pulpitis Chronic Pulpitis Necrotic pulpitis Periapical abscess or cyst.
Treatment Sedative, temporary filling followed in two weeks with a well-based permanent restoration. Root canal therapy, if irreversible.  Root canal therapy Root canal therapy or extraction of unrestorable tooth. Root Canal therapy and/or surgery or extraction of unrestorable teeth



Case History
A 39 year old female scuba diving instructor was referred to my office because of lower left jaw pain which occurred during diving. She described it as a tooth squeeze during several dives while she was teaching an advanced open water dive course in Columbus Isle, Bahamas.

Her first dive of the day was a multilevel dive to 120 feet. No sensation occurred on descent. However, on ascent at approximately 50 feet she felt some discomfort. The pain became more intense from 40 feet to the surface.

During the surface interval the pain diminished and she elected to continue diving. She felt pain throughout the entire dive, including the descent. It became nearly unbearable during ascent. Her tooth and gum remained tender and sore for several more days.

She visited a dentist in Nassau, Bahamas. Since the offending tooth had a root canal, and technically, should not be capable of feeling pain because it contained no nerve, the dentist assumed that her tooth had an air pocket with trapped air or that she had an infection in the gum surrounding the tooth. The gum was red and sore at the time. Antibiotics were prescribed and her teeth were cleaned.

Five days later she was teaching scuba classes in a swimming pool, but she had no symptoms. A day later. she conducted an open water dive. Most of the dive was in 28 feet and was free of pain. However, once she started the tour portion and reached 33 feet she again felt a sharp pain, but the pain never changed, even when she went to 48 feet. The ascent, however, was very painful and the tooth was again tender for several more days.

She again returned to the dentist in Nassau and more antibiotics were prescribed. The patient then waited ten days before getting back in the water and again felt pain during the descent to 44 feet. She continued down to 125 feet with no increase in pain but as before, ascent resulted in acute pain starting at 30 feet to the surface.

Because her job was being affected by this problem, she flew into Miami for another examination.

She came to my office in no acute Pain. Her medical history was non-contributory, and she appeared to be in excellent condition. She had obviously spent a great amount of time making sure that she received high quality dental care.

She indicated that she clenched her teeth during sleeping, and the degree of wear on her teeth confirmed that they were exposed to significant amounts of wear. Generalized gingival recession consistent with bruxism (clenching) was apparent.

The restorations in her mouth consisted mostly of gold onlays on the larger restored teeth in the back of the mouth. These are the most susceptible to wear and chewing forces. Her previous dentist had wisely chosen these strong restorations to reinforce these teeth because of her history of clenching. Gold onlays resist biting forces better than silver fillings and are always preferable over silver fillings when more than half of the tooth surface t be restored must be removed. Gold can also reinforce a tooth and help prevent fracture of the cusps --- especially in persons with strong bites or who clench their teeth. Her remaining restorations were small silver alloys-- appropriate for the situation.

She indicated the lower left first molar as the offending tooth. It was restored with a large gold onlay which covered all the cusps on the tooth. On the buccal (cheek) side of the tooth was a very small silver filling which touched the edge of the gold onlay. It was almost certainly placed after the gold had been completed -- in all likelihood to repair a small cavity which can form in the groove that extends to the cheek portion of the lower molar teeth. No significant fractures in this or the other teeth could be seen.

The upper and lower molar teeth all had large gold restorations. The frequency of dental problems increase with the number and size of the restorations present. Many dental pains commonly refer on the same side, both upper and lower. The upper and lower left teeth, therefore, were all suspect. An oral exam was done, and x-rays of the upper and lower left molar teeth were taken. All teeth were tapped firmly with the end of a blunt metal dental mirror to check for sensitivity to percussion -- often associated with inflammation of the periodontal ligament (the membrane which surrounds and supports the tooth in the socket). Cold air was applied to the same teeth with no significant results.

X-rays were essentially negative for decay or abscesses on both the upper and lower teeth. The upper maxillary sinus could be partially visualized on the x-rays and had normal radiographic appearance -- with no signs of clouding or lesions visible. She said she didn't have a cold or sinus congestion during or prior to the onset of symptoms. In addition, she experienced no symptoms on the flight from the Bahamas to Miami. The only significant radiographic finding was the root canal filling on the lower left first molar.

The lower left first molar had what appeared  to be reasonably well performed root canal treatment. There was difficulty visualizing the root tips of the particular tooth, and there was some question as to whether the root canal was well sealed to the end of one of the roots. Although difficult to visualize, it was my impression that either the front (mesial) root of the tooth was filled with root canal material slightly short of the end (apex) of the tooth or perhaps there was some washout of the cement at the apex - something I have seen happen in chronic clenchers. The periodontal membrane surrounding this apex also appeared thickened but intact-- again this could be consistent with clenching, but it can also be associated with disease. No radiolucent or darkened area appeared between the separation of the two roots of the tooth (often a sign of either a fractured tooth or a periodontal infection).

The affected areas were examined with a periodontal probe and found to be within normal limits (3 mm or less). However, there was some slight gum recession -- most probably attributable to her clenching -- and as a result, the probe could be slightly inserted into the beginning of the division of the two roots of the affected molar. Seeing this i assigned the tooth a Grade I bifurcation classification. Tissue color was normal and no bleeding upon probing was noted. The patient experienced no unusual discomfort to the probing procedure. The x-rays showed the lamina dura (the dense outer coating of bone between and around the teeth) to be intact and therefore appeared normal.

Her positive response to questioning about clenching also raised the possibility that somehow she was also suffering from temperomandibular joint (TMJ) dysfunction syndrome. She said she normally experiences no pain in the jaw joints during or after diving, and an examination of her internal pterygoid muscles revealed that they were not tender. I was left with several differential diagnoses:
- A fractured tooth
-A fractured root
-A leaking or incompletely filled root canal which had somehow allowed the accumulation of gas pressure during the dive and then allowed this gas to escape rapidly or explosively into the periodontal ligament space or apical pathology--- which caused acute pain followed by lingering soreness.
-A leaking filling
-TMJ syndrome
-Referred pain from another tooth or the maxillary sinus
-Referred cardiac symptoms of angina pectoris.

Referring to Table 1, her symptoms and signs (although not conclusive) most closely fit Class IV barodontalgia.

The patient was referred to an endodontist (a root canal specialist) because of the potential difficulty of retreating an old root canal tooth. He successfully removed all the old root canal space. This would be consistent with some form of leakage associated with the old root canal filling and with the formation of a potential space for the accumulation of gas.

Since the tooth has been retreated with a new root canal, her symptoms have not returned. For safety's sake and for ease of future retreatment, the tooth, for now, has been filled with a cement liner and silver alloy filling inserted directly into the gold onlay. All remaining air spaces under the filling and root canal have been removed. In the future if the tooth remains asymptomatic, an endopost and core will be fabricated, and a crown or another gold onlay will be made and cemented.

Should her symptoms return, then the possibility of split or fractured root and/or cystic or other chronic pathology associated with the root must be considered. Should this occur then surgery or extraction are the only remaining options.

This case is interesting because it  doesn't fit the classical symptoms of dental barotrauma or odontalgia. Generally it is associated with a living tooth having some decay or having a poorly fitting or leaking filling rather than a root canaled tooth with no nerve. Also, the pain is usually on ascent rather that descent and ascent. Red and painful gums are also unusual findings.

Conclusion
Considering the total number of certified divers, there is a significant chance that barotrauma involving the teeth will occur.

It is important that divers seek regular dental checkups and proper dental treatment. The removal of caries and the placement of adequate restorations are extremely important. Equally important are radiographic examinations to detect problems associated with roots and apices of teeth -- especially if there are old root canals, abscesses or cystic lesions present.

A proper dental exam should include periodontal exams and periodontal probing of the gums for infections. Avoid diving within 24 hours of most dental treatment and even longer intervals following dental surgery and root canal therapy.

Should you experience dental pain during diving, repetitive dives would not be appropriate. Don't assume that the problem will disappear and future diving will be OK without professional follow-up. Serious consequences such as infections, loss of fillings or other restorations, and even the immediate destruction of a tooth can result.

If dental examination fails to identify the problem, then an examination by a physician would be appropriate to examine the sinuses or even to evaluate the potential that the pain was referred from the heart. Sometimes the only symptom experienced during an angina episode is a pain which may be referred to the left arm, the neck or even the lower jaw.

by Laurence Stein, DDS
Diving Medicine Online Dental Consultant
PADI Divemaster D-35892
DAN Referral Physician Team (2000) 


Thanks to Larry Stein, DDS and Renee Duncan, Editor of Alert Diver, DAN, for allowing us to use this material.




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