Diver’s Mouth Syndrome

 

The “diver’s mouth syndrome” (DMS) was described by Goldstein and Katz in 1982 in the New York State Dental Journal.

It is an acute form of temporomandibular dysfunction syndrome affecting the population of scuba divers, impacting between 24% and 68% of them according to various statistics, with a slightly higher incidence in women.

Etiopathogenesis and Predisposing Factors

The main factor associated with the onset of this condition in divers is the continuous use and clenching of a mouthpiece for a determined period, which causes mandibular advancement and anterior displacement of the articular disc. This unstable position of the temporomandibular joint (TMJ), along with sustained muscle contraction, emotional stress, and cold water temperature, are risk factors for diver’s mouth syndrome.

The scuba equipment responsible for supplying air to the diver consists of three parts:

• A tank that houses air or another mixture of compressed breathable gases. There are various types of tanks, depending on the material they are made from (steel or aluminum) and their capacity, with the most common being 12 or 15 liters.
• A regulator, whose function is to reduce the pressure of the air in the tank and provide it to the diver at a pressure equal to the ambient pressure during each breath, regardless of the depth. This type of regulator was developed by Cousteau-Gagnan in 1943.
• A mouthpiece attached to the regulator, allowing it to be placed in the diver’s mouth. Mouthpieces, typically made of rubber or silicone, can be standard, suitable for all divers, with or without palatal support, or customized, adapted to the mouth of each diver. All of them consist of a tube that connects to the demand valve of the regulator and an oral piece that fits between the diver’s teeth and lips, helping to seal it.

 

 

Figure 2: From left to right: standard non-palatal mouthpiece, standard palatal mouthpiece, and customized mouthpiece.

The first bibliographic references on the temporomandibular dysfunction of divers are from Pinto (1966) and Roydhouse (1977). These authors suggested that the use of a mouthpiece during diving could cause local inflammation at the TMJ, which in turn could trigger Eustachian tube blockage and potentially affect the inner ear, leading to vertigo and disorientation.

In 1978, Ingervall et al. studied the muscle activity required to keep the mouthpiece in the mouth using electromyography. They demonstrated that customized mouthpieces produced less electromyographic activity and therefore required less muscle tension to be maintained in the mouth than standard mouthpieces.

In 2001, the British researcher Hobson conducted a study using lateral skull radiography and cephalometry to compare the mandibular position produced by using a commercially available standard non-palatal mouthpiece versus two types of experimental mouthpieces, one semi-customized and the other fully customized, and compared to normal occlusion. (Figure 10). He observed that the standard mouthpiece caused the greatest mandibular displacement (measured by an increase in the SNB angle or Sella-Nasion-Point B angle of Downs and by negative overjet or decrease in incisal overjet, the distance between the incisal edge of the upper incisors and the labial surface of the lower incisors).

 

 

Figure 3: Diagram taken from Hobson’s 2001 study, showing the average mandibular position in cephalometry performed during the use of customized, semi-customized, and standard mouthpieces. Normal occlusion without a mouthpiece is also shown as a reference.

Figure 4: Main angles and distances used in cephalometry. In red, SNB angle; in green, Mx-Mn angle. Medical Dictionary, 2011, modified.

In 2004, Balestra et al. conducted a study on 30 TMJs (15 divers) using magnetic resonance imaging to compare joint position in three conditions: maximum intercuspation (mouth closed), with a standard mouthpiece, and with a 40 mm opening. Their objective was to determine if the joint adopts an unstable position during diving that could trigger temporomandibular dysfunction. According to these authors, the prolonged unstable position of the TMJ during diving can induce pain due to tension in the highly vascularized and innervated retrodiskal part of the joint.

Koob et al. conducted a retrospective cohort study in 2005 at the University of Heidelberg (Germany) on 296 divers using questionnaires, aiming to determine the prevalence of TMD and possible risk factors for developing joint or muscle pain in divers. They concluded that dental clenching, both nocturnal and diurnal, and patients with limited mouth opening are more predisposed to experiencing pain in the TMJ and/or associated muscles after diving.

In the same year, Rubio Calle et al. from the National University of San Marcos in Peru conducted a study comparing 35 professional divers and 35 non-diving individuals. They concluded that diving activity is a risk factor that increases the severity of muscular and articular temporomandibular disorders; according to these authors, divers are 4.07 times more likely to have moderate and severe muscular and articular temporomandibular disorders, with statistically significant differences.

In 2008, Viskic et al. from the University of Zagreb (Croatia) published a study also using questionnaires and the Research Diagnostic Criteria for Temporomandibular Disorders by Dworkin and LeResche, comparing a group of 31 professional divers and a control group of 29 non-divers. They concluded that professional scuba divers can be considered a risk group for the onset or worsening of TMD.

In 2012, Oztürk et al. from the Department of Otolaryngology at the Istanbul Medical School stated that the use of the regulator mouthpiece increases the risk of temporomandibular dysfunction in scuba divers, as the total weight of the regulator is transmitted directly to the temporomandibular joint, causing joint and periauricular disorders. For them, the effort to hold the mouthpiece is a recognized risk factor in the development of temporomandibular disorder. Between 2006 and 2011, they collected 97 cases of divers with referred pain in the temporomandibular area, of which 14.43% were diagnosed with temporomandibular dysfunction due to diving. Additionally, divers were classified according to their level of experience, and it was found that temporomandibular disorders are more frequent in inexperienced divers.

In 2013, Farronato et al. from the University of Milan studied the prevalence and risk factors of temporomandibular disorders in 20 divers from the Italian Navy’s special forces, using electromyography before and after immersion, confirming the high incidence (up to 90%) of this pathology and its relationship with the type of mouthpiece, the presence or absence of pre-existing occlusal alterations, environmental conditions, and psycho-physical stress.

In 2014, Lobbezzo et al. from the University of Amsterdam conducted a study also using questionnaires on 536 German divers to investigate predisposing factors for the onset of temporomandibular disorders in divers. According to these authors, bruxism or dental clenching (similar to Koob in 2005), strongly biting the mouthpiece while diving, and its poor quality are the three main predisposing factors for the onset of temporomandibular disorders in divers, while diving in cold water would be a protective factor against temporomandibular pain, contrary to the opinions of Jones et al. in 1990, Hobson in 1991, and Aldridge et al. in 2004, who believed that cold water favored mandibular stiffness and the onset of temporomandibular dysfunction.

In 2015, Lobo Sanz A and Beltrán de Yturriaga C conducted experimental field research, finding statistically significant differences between the group using a standard mouthpiece and the group using a customized mouthpiece. To study the difference between the two mouthpieces, they mounted plaster models of a diver patient on a semi-adjustable Quick Master® articulator. After adjusting the right and left condylar trajectory inclination (CTI) with a protrusive record and keeping the Bennett angle at 0° to measure pure protrusion without lateral displacement, they measured and photographed the differences between the two mouthpieces. As shown (Figure 12), the standard mouthpiece caused an 8 mm mandibular advancement, while the customized mouthpiece caused a 4 mm advancement. There was also a greater increase in vertical dimension (VD) with the standard mouthpiece compared to the customized one, as well as a lack of posterior occlusal support with the standard mouthpiece. This lack of joint and occlusal stability, combined with the clenching of the mouthpiece due to the emotional stress generated in this sport, would induce muscular and joint overload, thus causing the three main symptoms: pain, limitation of mandibular movements, and joint noises.

Thus, a group of 38 divers with random mouthpieces and no prior occlusal pathology underwent a study of both temporomandibular joints before starting a series of dives over 7 days and at the end of each diving day. In each session, maximum mouth opening, body temperature (oral and ear), and thermography of the temporal, masseter, and joint areas were measured, as well as local pain using visual analog scales. Additionally, to perform a correct differential diagnosis regarding otic pathology and to study the possible relationship between temporomandibular disorders and equalization problems, systematic otoscopic and tympanometric evaluations were also performed.

 

Figure 5: Previous study comparing vertical dimension (VD) and mandibular advancement between a standard mouthpiece (left) and a customized mouthpiece (right).

21.1% of the divers experienced TMJ dysfunction without associated otic pathology; all of them used a standard mouthpiece, resulting in 40% of divers with this type of mouthpiece experiencing significant temporomandibular pain. However, there were no divers with pain from this cause and without otic pathology in the customized mouthpiece group, with a significant difference (p<0.05) between the two groups. (Figure 6).

 

Figure 6: Graph of temporomandibular pain by group

Regarding the tympanometric records obtained in our study, we observed a worsening in both groups between the first and third day and a subsequent maintenance until the last day, where we found a statistically significant difference in the behavior of the groups between the sixth and seventh day. Here, values improved in the customized mouthpiece group and worsened in the standard mouthpiece group (Figure 14), where the hypertonia of the tensor tympani muscle would lead to tubal dysfunction, as described in the otognathic syndrome, increasing the likelihood of developing barotrauma of the middle and/or inner ear.

 

Figure 7: Evolution of tympanometry values over the week, by group.

In summary, the main risk factors for the onset of Diver’s Mouth Syndrome are:

• Prolonged or repeated dives, which require sustained contraction of the muscles involved in the TMJ.7,31,36,37,43,44.
• The use of standard mouthpieces,7,38,39,40,49 which do not account for the diver’s articular and occlusal determinants, leading to a forced mandibular protrusion lacking posterior occlusal support, thus creating an unstable joint and muscular position, as well as pinching the retrodiscal area.40
• The emotional stress of the diver, which can be influenced by their personality, lack of experience, or the characteristics of the dive.7,44.
• Cold water temperature,32,34,48 although some authors47 suggest it could have a protective role.
• Female sex, possibly due to anatomical differences in mandibular angulation and masticatory muscle insertion,34 as well as greater ligamentous laxity and elasticity.40
• The presence of pre-existing TMJ pathology (such as arthritis or arthrosis), bruxism, or occlusal abnormalities.7,42,47.

 

Clinical Presentation of Diver’s Mouth Syndrome

Since Diver’s Mouth Syndrome is an acute variant of temporomandibular joint dysfunction syndrome, it will present with the same symptoms as described earlier. The main symptoms are therefore localized pain in the TMJ and the involved muscle groups, functional disorders of the joint, primarily limited mobility, and the appearance of joint noises associated with mandibular movement.

As we have seen, radiating pains such as headaches or neck pain may also occur, along with otological symptoms such as earache, tinnitus, vertigo, or hearing alterations, which constitute the so-called otognathic22 or otomandibular23 syndrome.

Lastly, the hypertonia of the tensor tympani muscle that occurs in mandibular disorders can lead to tubal dysfunction, making it more difficult to equalize the pressure changes in the ear, predisposing the individual to barotraumatic ear pathology.

Diagnosis

The diagnosis of diver’s temporomandibular dysfunction, like any other TMD, should be based on information obtained through medical history, physical examination, and the psychosocial factors present in the patient. It is also important to document the painful and dysfunctional symptoms present, as well as any auditory, speech, and swallowing problems the patient may experience. Comprehensive assessment of the joint complex should include orofacial tissues, muscle and neurological function, occlusion, and mandibular movements, as well as identifying possible parafunctional habits.50

While all of the above is essential, at times we must rely on various imaging techniques to diagnose the patient’s clinical condition. Magnetic resonance imaging (MRI) is the preferred technique for functional and pathological diagnosis of the TMJ, due to the anatomical and functional information it provides, being the reference test for evaluating soft tissues (muscles, ligaments, meniscus), both in static and dynamic positions. Additionally, it avoids ionizing radiation and has a specificity of 96% and a sensitivity of 98%.50

Experimentally, muscle contraction involved can be demonstrated through electromyography, and indirectly through cutaneous thermography of the temporal, masseter, and TMJ areas, which show increased temperature in affected individuals.

Furthermore, when the diver reports symptoms such as earache, a feeling of blockage, or hearing loss, a differential diagnosis between temporomandibular dysfunction and ear pathology, mainly external otitis, ototubaritis, and barotraumatic otitis media, must be made. When tinnitus or associated vertigo is present, inner ear involvement must also be ruled out. Early otoscopy is essential, and as soon as possible, audiometry and impedancemetry should be performed, and if necessary, vestibular tests.

Prevention

To prevent the onset of Diver’s Mouth Syndrome, any pre-existing temporomandibular or occlusal pathology should be corrected, avoid very prolonged or successive dives, especially in cold water, train in diving techniques to avoid additional psychophysical stress due to lack of experience, and primarily use a customized mouthpiece on the regulator. Ideally, it should be made of a flexible, thermoformable, hypoallergenic material such as silicone. Its design should include the extension of the labial flanges in the buccal vestibule up to the first molar to improve support retention and lip seal, and the extension of the interdental biting tab to the molars. Additionally, the mouthpiece should be tailored to the individual’s articular and occlusal characteristics.34,53,54

Treatment

The treatment of Diver’s Mouth Syndrome is similar to that of any other acute presentation of temporomandibular dysfunction. However, its management should be interdisciplinary rather than multidisciplinary, meaning that the different professionals should work in connection and coordination to complement the various therapies rather than working in isolation. This approach directly involves dentists, oral and maxillofacial surgeons, physiotherapists, psychotherapists, and dental prosthetists. Indirectly, other professionals who may be involved include radiologists, rheumatologists, internists, anesthesiologists, traumatologists, and orthodontists.

The treatment of Diver’s Mouth Syndrome can be divided into three phases57:

1st Phase: Pain Relief

The initial phase of treatment focuses on pain relief, which is the main symptom reported by the patient.

The first-choice therapeutic measure is usually pharmacological treatment55,56,57. Analgesics (paracetamol, metamizole, opioids), non-steroidal anti-inflammatory drugs (NSAIDs), and/or systemic corticosteroids, administered orally or parenterally, will be the main options. In cases of intense pain and poor response to systemic treatment, intra-articular corticosteroid injections can also be performed9,16. Additionally, muscle relaxants with central or peripheral action may be used. The most commonly used oral central muscle relaxants include benzodiazepines (diazepam, lorazepam, alprazolam, etc.), baclofen, cyclobenzaprine, carisoprodol, tizanidine, and methocarbamol. Given their potential side effects on the central nervous system, treatment with these drugs should always start with low doses, gradually increasing if necessary, until reaching the recommended dose. Botulinum toxin stands out as a peripheral muscle relaxant, which can be injected as an adjunct in the masticatory muscles. Finally, tricyclic antidepressants, such as nortriptyline or amitriptyline, administered in low doses, help alleviate pain, reduce bruxism, and muscle contraction9,16.

For cases where the response to pharmacological treatment is insufficient, or repeated episodes of Diver’s Mouth Syndrome occur despite following preventive measures, other possible conservative therapies include:

• Physiotherapy57: This includes various modalities, such as exercises to stretch and strengthen jaw muscles, massages, kinesitherapy, physical therapy with ultrasound, laser, microwaves, transcutaneous electrical nerve stimulation, etc. Patients should also be advised on proper dental and oral hygiene habits, muscle relaxation exercises, and to chew on both sides of the mouth regularly. Unhealthy habits such as smoking, teeth clenching, excessive gum chewing, wide mouth openings, or adopting incorrect head and neck positions, both during and outside of diving, should be discouraged.
• Psychotherapy55,56,57: This helps divers understand the factors and behaviors that may exacerbate their pain, such as clenching or grinding their teeth, so they can avoid them. It also teaches relaxation techniques to better manage stress.

2nd Phase: Condylar Repositioning

This phase aims to place or reposition the condyles in their centric position using deprogrammers and/or occlusal splints57,58. These removable devices, usually made of hard acrylic resin, are typically adjusted over the upper teeth to establish an optimal occlusal state, improving the anatomical relationship between the mandibular condyle, the articular disc, and the glenoid cavity. This allows the joint to adopt a more orthopedically stable position, reducing abnormal reflex muscle activity, and alleviating TMJ dysfunction symptoms in most cases. Additionally, the splint protects the dental and supporting structures from abnormal forces, preventing their alteration or wear.

3rd Phase: Occlusal Repositioning

This final phase involves irreversible occlusal therapy, aiming to adapt the patient’s occlusion to the “imposed position by the joints,” making the necessary occlusal modifications so that dental contacts during function do not displace the joints from their centric relation achieved in the previous phase. This includes several procedures: selective grinding, orthodontics, prosthetics, and orthognathic maxillofacial surgery.

• Selective Grinding: A technique involving the wear of dental structures that impede the establishment of physiological occlusion.
• Orthodontics: Sometimes necessary to resolve dental malocclusions or other occlusal issues that could cause or aggravate TMD.
• Prosthetic Reconstruction: Required for some patients to achieve a stable occlusion in harmony with other orofacial structures and thus resolve TMD.
• Surgical Indications: Generally few, surgery is only performed in cases with advanced pathology where conservative methods have failed. Current techniques include:
  • Arthrocentesis: A minimally invasive procedure performed under local anesthesia, involving joint puncture and irrigation to release adhesions and remove inflammatory debris and byproducts, as well as administering intra-articular corticosteroids.
  • Arthroscopy: Allows direct visualization of the joint, assessment of disc displacement, and possible presence of synovitis, chondromalacia, or adhesions, with their release and disc repositioning if necessary, being less invasive with fewer complications than open surgery, though with some limitations.
  • Open Joint Surgery: Reserved for chronic disc displacement cases that may lead to arthritis, condylar resorption, or disc deformation, which loses its flexibility and vascularization, secondarily damaging the fibrocartilage covering the condyle and the glenoid fossa.

This type of surgery allows direct access to the TMJ through endaural, preauricular, or postauricular approaches, enabling meniscoplasty, condylotomy, condylectomy, and eminectomy, among others. It remains an effective and highly safe option. However, given that it involves more risks than other procedures, its indication should be carefully considered, weighing its advantages and disadvantages in each case55,56,57.

Bibliography 

31. Goldstein GR, Katz W. Divers mouth syndrome. N Y State Dent J. 1982 Oct;48(8):523–525.
32. Hobson RS. Temporomandibular dysfunction syndrome associated with scuba diving mouthpieces. Brit J Sports Med. 1991 Mar;25(1):49–51. 

33. Taddey JJ. Scuba diving and TMD. Cranio. 1993 Jan;11(1):73–74. 

34. Aldridge RD, Fenlon MR. Prevalence of temporomandibular dysfunction in a group of scuba divers. Brit J Sports Med. 2004 Feb;38(1):69–73. 

35. Cousteau JY, Gagnan É. Demand regulator for breathing apparatus.

         Patente de EE.UU. US3095890. 

36. Pinto O. Temporomandibular joint problems in underwater activities. J Prosthet Dent. 1966 Jan 1;16: 772–781 

37. Roydhouse N. The jaw and scuba diving. J Otolaryngol Soc Aust. 1977 Jan 1;4: 162–165. 

38. Ingervall B, Warfvinge J. Activity of oro-facial musculature during use of mouthpieces for diving. J Oral Rehabil. 1978 Jul;5(3):269–77 

39. Hobson RS, NewtonJP. Dental evaluation of scuba diving mouthpieces using a subject assessment index and radiological analysis of jaw position. Brit J Sports Med. 2001 Apr; 35:84-88. 

40. Balestra C, Germonpré P, Marroni A, Snoeck T. Scuba diving can induce stress of the temporomandibular joint leading to headache. Brit J Sports Med. 2004 Feb;38(1):102. 

41. Matsui R, Ueno T, Ohyama T. Fabrication of a custom diving mouthpiece using a thermoforming material. J Prosthet Dent. 2004 Oct;92(4):392–394. 

42. Koob A, Ohlmann B, Gabbert O, Klingmann C, Rammelsberg P, Schmitter M. Temporomandibular disorders in association with scuba diving. Clin J Sport Med. 2005 Sep;15(5):359–363. 

43. Rubio Calle JA. El Buceo como factor de riesgo en la prevalencia de trastornos temporomandibulares musculares y articulares. Universidad Nacional Mayor de San Marcos. Programa Cybertesis Perú; 2007. 

44. Viskic J. Evidence of TMD in professional SCUBA-divers from Croatia. Neuroscience/TMJ. Toronto; 2008. 

45. Dworkin SF, LeResche L. Research diagnostic criteria for temporomandibular disorders: review, criteria, examinations and specifications, critique. J Craniomandib Disord. 1992;6(4):301–355. 

46. Oztürk O, Tek M, Seven H. Temporomandibular disorders in scuba divers-an increased risk during diving certification training. J Craniofac Surg. 2012 Nov;23(6):1825–1829. 

47. Lobbezoo F, van Wijk AJ, Klingler MC, Vicente ER, van Dijk CJ, Eijkman MAJ. Predictors for the development of temporomandibular disorders in scuba divers. J Oral Rehabil. 2014 Jul 31;41(8):573–580. 

48. Lobo Sanz A, Beltrán de Yturriaga C. Estudio experimental comparativo sobre el uso de boquilla personalizada frente a boquilla estándar en la práctica del buceo con escafandra autónoma para la prevención del síndrome bucal del buceador. (Internet). Madrid; 2015. [ acceso 21 de julio de 2019]. Disponible en: https://eprints.ucm.es/32753/1/T36253.pdf 

49. Mack PJ, Hobson RS, Astell J. Dental factors in Scuba mouthpiece design. Br Dent J. 1985 Feb 23;158(4):141–142. 

50. López López J, Chimenos Küstner E, Blanco Carrión A, Reselló Llabrés X, Jané Salas E. Diagnóstico por la imagen de los trastornos de la articulación craneomandibular. Av. Odontoestomatol 2005; 21-2: 71-88.
51. Uzun C. Evaluation of predive parameters related to eustachian tube dysfunction for symptomatic middle ear barotrauma in divers. Otol Neurotol. 2005 Jan;26(1):59–64. 

52. Ramos CC, Rapoport PB, Brito Neto RV. Clinical and tympanometric findings in repeated recreational scuba diving. Travel Med Infect Dis. 2005 Feb; 3(1):19–25. 

53. Newton JP, Hobson RS, Sturrock KC. The design and construction of customised mouthpieces for subaqua diving. Eur J Prosthodont Restor Dent. 1995 Sep;3(5):223–226. 

54. Toshiaki H, Takahiro O, Yoshinobu M. Influence of wearing a scuba diving mouthpiece on the
55. stomatognathic system. Considerations for outhpiece design. Dental Traumatology 2016; 32: 219-224. 

56. Edward F. Wright DDS, Sarah L. North PT. Management and Treatment of Temporomandibular Disorders: A Clinical Perspective. J Man Manip Ther. 2009; 17(4): 247–254. 

57. Bejarano-Panadés N, Corral JL, Juan-Fernández JM. Enfermedades del oído externo y la articulación temporomandibular en el buceo. Acta Otorrinolaringol Esp 2007;58 Supl 2:28-33 

58. García Martínez I, Jiménez Quintana Z, Solana L, Sáez Carriera R. Actualización terapéutica de los trastornos temporomandibulares. Rev Cubana Estomatol [Internet].2007 Sep [citado 2019 Ago 27] ; 44(3).Disponible en: http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S0034-75072007000300013&lng=es. 

59. Castañeda Deroncelé M, Ramón Jiménez R. Uso de férulas oclusales en pacientes con trastornos temporomandibulares. MEDISAN [Internet]. 2016 Abr [citado 2019 Ago 25]; 20(4): 530-543. Disponible en: http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S1029-30192016000400014&lng=es.