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Purpose: To describe a method for customizing scuba diving mouthpieces, to examine their usability, and to assess divers' satisfaction with their use.Materials and Methods: A rational method for fabricating custom-made mouthpieces for scuba diving was developed. Twenty scuba divers agreed to use a custom-made mouthpiece for at least 4 weeks. After mouthpiece use, participants completed an 11-item questionnaire.Results: Custom-made mouthpieces had significantly lower scores for all items on the questionnaire except uncomfortable sensation, indicating that they were more comfortable than ready-made mouthpieces.Conclusion: It can be concluded that these novel custom-made mouthpieces for scuba diving offer greater comfort than ready-made mouthpieces. [ABSTRACT FROM AUTHOR]

Scuba diving is one of the most rapidly growing marine sports in Japan. Many divers continuously clench the mouthpiece for scuba diving (SD mouthpiece) during the dive, and experience unpleasant symptoms of fatigue of the temporomandibular joint or oro-facial muscles after the dive. The purpose of this study was to investigate the effect of customization of the labial flange and platform of the SD mouthpiece on oro-facial muscle activities during the dive by simulating the state of holding the SD mouthpiece under water. EMG activity of the anterior belly of temporal muscles, masseter muscles and orbicular oris muscles while holding the SD mouthpiece for 7 min was recorded and integrated value of muscle activity as a parameter of muscle activity with and without customization was compared in four male beginner divers (28±2 years). Muscle activity of temporal muscles increased when the labial flange was narrowed, that of masseter muscles decreased when the labial flange was widened or the platform was extended, and that of orbicular oris muscles increased when the labial flange was widened or the platform was shortened. These results suggested that customization of the SD mouthpiece may improve muscle activities while holding the mouthpiece for scuba diving. [ABSTRACT FROM AUTHOR]

When scuba diving, divers must wear mouthpieces in order to breathe underwater, and mouthpiece strength appears related to the safety of the scuba diving experience. However, the strength that a mouthpiece should possess for safe diving has not been investigated until now. Furthermore, in Japan there are no safety standards or laws involving the strength of commercially available mouthpieces. In the present study, we investigated the tensile strength and tearing strength of the silicone rubber material used in commercially available mouthpieces under the following conditions : 1) type : heat-cured rubber (HCR) or liquid injection molding system (LIMS) ; 2) use : nipple of the feeding bottle or mouthpiece compliant with the Food Sanitation Act ; 3) color : transparent or semitransparent ; and 4) hardness : 40-70 As. From the data available on manufacturers websites, it was suggested that silicone rubber material for scuba diving mouthpieces had tensile strength of 7.8 MPa or more and tearing strength of 25 N/mm or more. [ABSTRACT FROM AUTHOR]

Recently, the popularity of scuba diving has increased enormously in Japan. To breathe underwater, divers need to carry a tank filled with air when they dive. However, the humidity of the air in the tank is very low. Many divers complain of mouth dryness because they have to breathe dry air during a diving. Our previous studies indicated that customization of the scuba diver's mouthpiece (SD mouthpiece) could reduce the various burdens of TMJ and oro-facial musculature during a dive. Additionally, it is assumed that the structure of a custom-made mouthpiece provides more stimulation to the oral mucosa than a stock mouthpiece, which has the possibility to accelerate salivary secretion. In this research, we measured the salivary flow under three conditions (rest, wearing a stock-mouthpiece, and wearing a custom-made mouthpiece) in four subjects to investigate the influence of customization on salivary secretion, which might improve mouth dryness during a dive. As a result, the salivary flow brought forth from wearing a custom-made mouthpiece was significantly higher than at rest or with a stock-type mouthpieces in all the subjects. Our result suggested that customization of a SD mouthpiece is effective for improving mouth dryness during a dive. [ABSTRACT FROM AUTHOR]

Many divers often experience discomfort of the oromaxillofacial region during and/or after wearing a mouthpiece for scuba diving (SD mouthpiece). Recently several diving apparatus manufacturers have modified the SD mouthpieces to reduce the discomfort. However, there have been no reports which evaluated the shape and characteristics of commercially - available SD mouthpieces. In the present study, we observed and measured the shape and dimensions of various commercially-available SD mouthpieces in Japan. Then we tried to classify the shape of SD mouthpieces in order to consider the possible effects for solving the problems from the point of sports dentistry. The results were as follows. 1. The occlusal support area which located in the first premolar part in almost all of the commercially - available SD mouthpiece. 2. A comparison between premolars on both sides of the diver with labial flange at the position of 17.2 mm from the most anterior part on both sides of the SD mouthpiece would be useful to find the proper size of SD mouthpiece. 3. The size and shape of the connecting part of the regulator and SD mouthpiece were not uniform. This should be studied for improving the safety of the SD mouthpiece. 4. Among 33 SD mouthpieces studied, 14 were classified into the typical stock type, 17 were classified into the modified stock type and 2 were classified into the mouthformed type. 5. It was suggested that the modified stock type and mouthformed type SD mouthpiece may reduce the stress on the oro - facial musculature, the choking while diving, and the difficulty in holding the SD mouthpiece in case of teeth loss. [ABSTRACT FROM AUTHOR]

Although scuba diving is one of the most rapidly growing sports today, many divers feel temporo-mandibular joint or oro—facial muscle fatigue and soreness after diving. Commercially available mouthpieces for scuba diving have a common basic design : the platform is gripped with the canines and premolars, and the labial flange aids the lip seal. We previously investigated the effect of the shape of the mouthpiece used for scuba diving on the oro&#x2014facial musculature by electromyography, and reported that the activity of the masseter muscles was reduced when the labial flange was widened or the platform was extended, and that the activity of the orbicular oris muscles was activated when the labial flange was widened. In the present study, we examined the possibility of reducing oro—facial muscle fatigue during diving by customization of the mouthpiece. Three kinds of working ability such as maximal bite force, masticatory performance and endurance of isometric contraction of jaw closing muscles were measured before and after loading on three kinds of mouthpiece (Type A : original shape of commercially available mouthpiece, Type B : Platform was extended from canine to second molar, and Type C : labial flange was widened to the muscobuccal fold) worn by four subjects, and the extent of decline in the working abilities of each test subject was compared among each type of mouthpiece. The results showed that there was a significant decline in working ability after loading when subjects wore the Type A mouthpiece; however, no declines were found when subjects wore Type B and Type C mouthpieces. These results suggest that the customization of the labial flange and platform of the mouthpiece could reduce the fatigue of the oro—facial musculature during diving. [ABSTRACT FROM AUTHOR]

To create a more comfortable and safer environment for scuba diving, a safety standard for the mouthpiece for scuba diving (SD mouthpiece) will need to be established. To evaluate the safety of the SD mouthpiece, it is necessary to investigate the load on the SD mouthpiece during the dive. In this study, we subjected a SD mouthpiece to various magnitudes and directions of loading with a diving instructor holding the mouthpiece, and identified the load condition that approximates the load during the dive by sensory evaluation of the subjects and a constant method. As a result, the direction of the load which best approximated that during the dive was right side slanting forward. On the other hand, as for the 50% differential threshold of the magnitude which was evaluated approximately during the dive, it was suggested that the lower limit was 25-105 gf, and the upper limit was 75-315 gf. In this study, various factors such as individual difference of the sense or difference of diving condition have a profound effect on the result of this experiment. However, this result is very important as typical values of the experiment to verify the safety of SD mouthpieces. [ABSTRACT FROM AUTHOR]

We previously reported that a custom-made scuba diving mouthpiece inhibited forward movement of the mandible during a dive. However, the change in mandible position resulting from this customization may increase breathing resistance. In this study, we designed experimental mouthpieces with different mandible positions to examine the influence of mandibular position and volume of the mouthpiece on breathing resistance, by comparing peak flow in 4 male certified divers (age : 28.4± 3y). Mouthpiece design was evaluated under the following conditions : ①. Four different vertical positions of the mandible by changing the amount of bite raising by 0 mm, 2 mm, 4 mm, and 6 mm. ②. Three horizontal positions of the mandible by changing the amount of mandibular protrusion by 0 mm, 2 mm and 4 mm at the vertical position of the mandible raised by 4 mm. ③. Volume of the SD mouthpiece for a customized mouthpiece and a general commercially available mouthpiece. The following results were obtained : ①. All 4 subjects showed a signifi cant increase in peak flow in proportion to the amount of bite raising at 0 mm, 2 mm, and 4 mm. However, peak flow was unchanged at 4 mm and 6 mm. ②. Three of the 4 subjects showed no difference in peak flow for any of the 3 horizontal mandibular positions. In the remaining subject, peak flow decreased significantly when protrusion of the mandible was 4 mm. ③. No significant difference was found in peak flow between the customized and general commercially available mouthpieces used. These results indicate that customization of the regulator mouthpiece does not increase breathing resistance, thus increasing comfort for divers during a dive. [ABSTRACT FROM AUTHOR]