Mouth Guards    Dr. Padilla will present "Sports Dentistry: Trauma, Treatment and Prevention" at the CDA Scientific Session in Anaheim from 10 a.m. to 4:30 p.m. on Friday, April 9, in Room California D at the Anaheim Hilton and Towers and "Hands-on Custom-Made Mouth Guard Fabrication Course" from 9 a.m. to 1 p.m. on Sunday, April 11, in Room AR2 in the Anaheim Convention Center.

Pressure-Laminated Athletic Mouth Guards: a Step-by-Step Process

Of the variety of mouth guards available to the conscientious athlete for protection of oral structures, the pressure-laminated appliance provides the best fit and the most protection. The pressure-lamination technique, however, is not widely known among dentists. This article contains a step-by-step description of making pressure-laminated athletic mouth guards.

The field of sports dentistry is gaining acceptance from all members of the sports medicine team, including physicians, physical therapists, and athletic trainers. It is increasingly important for these individuals to be able to come to the dentist for the latest advice on prevention and treatment of orofacial injuries and related topics, including knowledge of custom-made pressure-laminated mouth guards.

The American Society of Testing and Measurements suggests three classifications of athletic mouth guards:

* Type I: stock. These are store-bought over-the-counter mouth guards. They are simply taken out of the packaging and immediately placed in the mouth. No attempt at fit is made. These are regarded as the least protective of all types of mouth guards and are the least expensive.

* Type II: boil and bite. These are also store-bought over-the-counter mouth guards. Some attempt at fit is made by boiling the mouth guard and trying to mold it to the teeth. The instability and uneven distribution of material, however, do not lend themselves to proper fit and protection.

* Type III: custom made. These are made from a cast of the athlete's mouth by either vacuum or pressure lamination. These are the mouth guards of choice for the dental professional to recommend to their patients and athletes.¹

Recently, the California Dental Association's Council on Community Health introduced an educational video underlying the need for dentist-diagnosed and -produced custom-made mouth guards. (California Dental Association and Tufty Productions, 1998). Dental professionals used to tell patients to wear a mouth guard without distinguishing between over-the-counter store-bought mouth guards and professionally made mouth guards. It is no longer suggested that patients seek the advice of sporting goods stores for their dentistry. The need to educate athletes, parents, and coaches about seeking the guidance of dental professionals is now even more important. The only options that should be suggested by dentists to their patients are custom-made mouth guards provided by health professionals. The comfort and fit of these mouth guards encourage higher compliance. The higher the compliance, the less the chance of injury because the custom fabrication of mouth guards ensures consistent thickness in critical areas of the appliance.

Dr. Ken Creighton, deputy chief medical officer for the 2000 Olympic Games in Sydney, Australia, and Dr. Brett Dorney, the games' dental director, have stated that the 2000 Olympics will be an opportunity to promote the best dental protection in "at risk" sports by using the latest pressure-laminated techniques. The Academy for Sports Dentistry is currently implementing a position statement that will promote the use of custom-made athletic mouth guards. In August of 1998, the Ontario Hockey League, the primary feeder league for the National Hockey League, mandated that all their players have dentist-fabricated mouth guards.

Most dentists familiar with custom-made mouth guards have made them using a vacuum machine. This machine -- common to most dental offices -- uses a heating element and up to one atmosphere of pressure to form a vacuum, thus adapting materials over casts of the mouth. This adaptation is poor when compared to results obtained with a pressure-lamination machine, which uses a heating element and up to 10 atmospheres of pressure (not vacuum) to better form a more intimate adaptation of the model using the material of choice. The machine demonstrated in this paper will be the Dreve Drufomat Machine (Distributed by Westone Laboratories, Colorado Springs, Colo.), although other machines may be utilized, such as the Biostar Machine (Great Lakes Orthodontics LTD, New York) and the Erkodent Erkopress Machine. (Glidewell Laboratory, of Newport Beach, Calif., fabricates the Playsafe Mouthguard with this machine, but it is not available for sale in the United States).

Comparison of Vacuum and Pressure Machines

It has been the authors' experience that the pressure-lamination machine is far superior in adaptation. Instead of the vacuum of less than 1 atmosphere used by the vacuum machine, positive pressure of up to 10 atmospheres is used. The key element, however, is the capability to laminate, which is only successful with high heat and pressure. The authors have been using pressure-lamination machines exclusively for several years. Besides athletic mouth guards, these machines can also be used for model duplication, custom trays, orthodontic retainers, implant stents, bleaching trays, bruxing appliances, snoring appliances, and denture repairs.

Not all American dentists and their patients are aware of the pressure-lamination technique. This paper will focus on the technique used for many years in Europe and Australia. There are qualified dental labs fabricating pressure-laminated mouth guards. However, dentists should be aware of the technique so they can make the mouth guards themselves or have the knowledge to fit, trim, and adjust these appliances once they arrive from the laboratory. Just as dentists fit, trim, and adjust dentures, partials, retainers, and other appliances, they need to do the same with custom-made pressure-laminated mouth guards. Knowledge of the fabrication procedure is imperative. Fit and compliance in wearing is essential to injury prevention.

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Below is the step-by-step process for the fabrication of an athletic mouth guard for a high school or collegiate basketball player in stable occlusion. A trimmed cast of the athlete's maxillary arch was fabricated using die stone. During the impression process, care was taken to include all vestibular borders, and these borders are intact on the model. The goal of using the mouth guard is to protect not only the teeth, but also the surrounding structures such as the alveolar bone and attached gingiva and mucosal tissues.²

Figure 1. The pressure-lamination machine being used is the Dreve Drufomat, which is used for the production of thermoformed dental appliances. The Drufomat is connected to an air compressor with operating pressure usually at 6 bar. The fabrication process is started by choosing the thickness and color of the ethyl vinyl acetate (EVA) laminate sheet. The thickness is determined by diagnosing the needs of the athlete with respect to age, level of competition, and history of past injury. For this example, the desired result is a 4 mm mouth guard, so two 3 mm sheets are laminated together. There is an approximate 30 percent shrinkage during the fabrication process, so by laminating two 3 mm sheets, the result will be a 4 mm mouth guard.

First, the Drufomat main and heater switches are turned on. Then a 3 mm blue sheet is selected for the first layer and placed in the disc positioning ring. The trimmed model is placed on the tray table slightly off center toward the lingual.

Figure 2. The clamping ring is placed over the EVA sheet to lock it into position.

Figure 3. The quartz heater and disc positioning ring are positioned over the model, and the EVA material is allowed to heat to formable consistency.

Figure 4. The EVA material will begin to slump as it heats. When it begins to touch the model, it is ready for the pressure to be activated.

Figure 5. On the upper left side of the Drufomat is a white button that activates the pressure. This button must be pressed at the same time that the quartz heater is removed from over the EVA material. The pressure chamber will drop over the model and form and pressurize the EVA to the model. A light will come on, thus signaling that one's hands can be removed from the white button and quartz heater shifter.

Figure 6. The material is allowed to cool under pressure in this position for at least 15 minutes.

Figure 7. Once the time has elapsed, the white button is pressed to release the pressure until the indicator light shuts off.

Figure 8. The heater lever is slowly pushed toward the cylinder. The pressure cylinder will rise.

Figure 9. The first layer of the laminated mouth guard is now formed. The clamping ring and the formed appliance can then be removed. The appliance will need to cool to room temperature to prevent distortion.

Figures 10 and 11. Once the mouth guard material is completely cooled, preliminary trimming may begin using a heated bard parker blade or scissors.

Figures 12 through 14. Care should be taken that the appliance is not trimmed excessively. Lingually, the palatal extensions should be removed. This allows for more comfort during speaking and breathing. Buccally, the mouth guard extensions should cover just like a denture, to full vestibular borders protecting the alveolar bone as well as the teeth from injury. The mouth guard should be trimmed back to the second molar.

Figures 15 through 17. The mouth guard is then ready for placement of stickers and identification. Any label machine can be used as long as it provides small (10 to 12 point) print. Black ink on clear tape should be used for light-colored mouth guards and white ink on clear tape should be used for dark-colored mouth guards. The dentist can ask the athlete what he or she would like on the mouth guard, perhaps a school name or logo across the front. The athlete's name should be placed on the side. The doctor's name and phone number should be placed on the other side.

Figure 18. The mouth guard is then ready for a second layer to be laminated in place. A clear sheet of EVA with the desired thickness, in this case 3 mm, should be used. The clear EVA sheet should be placed in the disc positioning ring. The model with the first trimmed blue layer is placed on the tray table slightly off center toward the lingual. At this point, the steps 1 through 4 (Figures 1 through 4) are repeated. Once the clear layer begins to melt to desired formable consistency, the fabrication is at a critical stage. The second layer must be hot enough to consistently and predictably laminate to the first blue layer. If this is not done, the two layers will not securely laminate and will separate in time.

Figure 19. The second clear layer must droop completely over the teeth on the model before the pressure chamber is activated.

Figure 20. The pressure chamber is activated as in step 5 (Figure 5) and the model allowed to cool under pressure. Steps 6 through 8 (Figures 6 through 8) are then repeated.

Figures 21 through 23. The clamping ring is removed, and the laminated mouth guard allowed to cool to room temperature, preferably overnight. This eliminates any chance of distortion and ensures a perfect fit.

Figures 24 through 27. Steps 10 through 14 (Figures 10 through 14) are repeated.

Figure 28. The internal lingual extensions should be marked with a pen to 1 to 2 mm from the teeth.

Figures 29 through 31. With a stone acrylic bur, the excess material is trimmed lingually to the marked extensions. The mouth guard is then placed back on the model, and the margins are feather-finished for comfort lingually, buccally and labially. Any interference with muscle extensions should be removed.

Figures 32 and 33. On a dental lathe, the mouth guard is further trimmed and smoothed to desired thickness with a scotch wheel.

Figures 34 and 35. Final finish and polish is placed with a chloroform saturated gauze.

Figures 36 and 37. The completed 4 mm custom-made pressure-laminated mouth guard. At this stage, it is critical to try in the mouth guard and check for fit and comfort. Slight trimming and adjusting may be necessary just as at any dental appliance insertion appointment. Special care should be taken to ensure a balanced occlusion. This may be done in the laboratory or directly at the chair with the patient, by slightly heating the occlusal surfaces of the mouth guard and biting down slightly and gently until all posterior teeth occlude. Special care should be taken not to bite down excessively and bite through the mouth guard. A minimal occlusal thickness of 3 mm is critical to ensure proper absorption of impact during competition.

Conclusion

In the authors' experience, the pressure-laminated mouth guard has been shown to be the most accepted mouth guard by athletes because of its precise fit, comfort, and predictability of thickness in critical areas. This fabrication procedure gives the sports dentist the capability to diagnose, design, and customize these protective mouth guards for the specific needs and requirements of any athlete, regardless of age, level of competition, sport played, and past history of injury and concussion. They can be made as thick or thin as necessary according to the dentist's diagnosis. Dentists, as health professionals, have an obligation to present all treatment options to patients and explain the differences. Once patients have the knowledge of what is best for themselves and their children, they will not seek their dentistry from sporting goods retailers.

Authors

Ray R. Padilla, DDS, is TK and chair of CDA's Council on Community Health.

Thomas Lee, DDS, is TK also.

References

1. Padilla R, Balikov S, Sports dentistry coming of age in the '90s. J Cal Dent Assoc 21(4):27-34, 1993.

2. Padilla RR, Felsenfeld AL, Treatment and prevention of alveolar fractures and related injuries. J Cranio-Maxillofac Trauma 3(2):22-7, 1997.

Related Reading List

Padilla R, Dorney B, Balikov S, Prevention of oral injuries. J Cal Dent Assoc 24(3):30-6, 1996.
Flanders R, Mohandas B, The incidence of orofacial injuries in sport: a pilot study in Illinois. J Am Dent Assoc Vol. 126:491-6, April 1995.

Dental Injury Fact Sheet. National Youth Sports Safety Foundation, Boston, Mass, C-1992.
Reports of Councils and Bureaus, Mouth protectors: 11 years later. J Am Dent Assoc 86:1365-7, June 1973.

Heintz WD, Mouth protection in sports. Physician Sportsmed 7(2), Feb 1979.

Chapman PJ, Nasser BP, Attitudes on mouthguards and prevalence of orofacial injuries in four teams competing at the Second World Cup. British J Sports Med 27(3):197-9, 1993.

Chapman PJ, Concussion in contact sports and importance of mouthguards in protection. Austral J Sci Med Sport March 1995, pp 23-7.

Park et al, Methods of improved mouthguards. First International Symposium on Biomaterials, Taejon, Korea, August 1993.

To request a printed copy of this article, please contact/Ray R. Padilla, DDS, 100 S. Vincent Ave., Suite 404, West Covina, CA 91790.