DATELINE: 6th June 2001

MOUTH STUDY
A British study has concluded that diving regulator mouthpieces can cause appreciable discomfort - and, in extreme cases, even bring on vertigo.
Researchers from Newcastle and Dundee dental schools asked six men to try out three mouthpieces, each for 45 minutes. The mouthpieces were a standard production item in rubber and silicone, designed for holding between the front and middle teeth; a semi-customised, silicone-only model; and a customised silicone unit.
Results, published in the British Journal of Sports Medicine, concluded that the customised mouthpieces, set from a cast of an individual's dentition to allow improved purchase by the rear teeth, caused least muscle pain and fatigue, facial and tooth discomfort, and jaw displacement, and required less effort to hold in place.
Jaw displacement was regarded as particularly important, as this causes inflammation which can affect the inner ear's balancing mechanism.
The custom mouthpiece needed 15 per cent effort to hold in place, compared with 22 per cent for the semi-customised and 34 per cent for the standard production unit. Effort increased with time for the others, but remained constant for the customised design.
The production unit led to almost twice as much muscle pain as the others, although the report stressed that the pain levels involved were not high. The study concluded that "the trend in scuba-diving mouthpiece design should be towards an increased level of customisation".
Customised units should be "seriously considered by divers who have previously had episodes of temporomandibular joint dysfunction or prolonged discomfort in jaw muscles following diving activities".

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