Fabricating an in-office mouth guard.

Millions of children are injured each year due to their participation in sports and fitness activities resulting in a cost to the government and their families for many billions of dollars. Many of these injuries can be prevented by utilizing safety resources. Flanders reported when mouth guards are worn in football, .07% of the injuries were orofacial, whereas in basketball, where mouth guards are not routinely worn, 34% of the injuries are orofacial. (1) The degree of injury varied from simple contusions and lacerations to avulsions and fractured jaws. The National Youth Sports Safety Foundation for the Prevention of Athletic Injuries, Inc. (NYSSF) reports that dental injuries are the most common type of orofacial injuries sustained during sports participation. (2) The NYSF also noted that victims of total tooth avulsions who do not have teeth properly preserved or replanted may face a lifetime dental cost of $10,000 to $15,000 per tooth, hours in the dentist chair, as well as possible development of other dental problems such as periodontal disease. In addition, NYSSF reported that there are approximately 15 million dental injuries and five million avulsed teeth. (2) The American Dental Association estimated that mouth guards prevent approximately 200,000 injuries each year in high school and collegiate football alone. Teenage girls constitute the fastest growing segment of adolescents participating in organized athletics. And, although the perception is that female athletes are less aggressive and have a reduced risk of injury, adolescent girls appear to have similar injury rates as boys in comparable activities.

Parents are more likely to require mouth guards for their sons than daughters, as well as for children participating in a mandatory mouth guard sport, a contact sport, or who had been previously injured. (3)

Special Consideration

Young athletes and other athletes with fixed orthodontic appliances need special consideration for mouth guards. Designing a mouth guard for young athletes can be a challenge for the dental practitioner due to the athletes' mixed dentition and constant changes including tooth eruption and facial growth. Perfecting a design can be achieved by incorporating space for tooth movement and growth of the arches. (4) External mouth guards for young athletes with mixed dentition are also recommended to avoid affecting the position of the teeth, specifically the maxillary anteriors. Long-term use of a mouth guard is not recommended as the guard itself must be changed contemporaneously with changes in the orofacial structures. Therefore, it is pertinent to closely monitor these athletes and their mouth guard usage.

Fabricating an athletic mouth guard for an orthodontic athlete can become complicated during the impression-taking aspect of the procedure. Orthodontic wires should be removed prior to taking the impression. Blocking out the bonded brackets with utility wax prior to the impression stage can decrease the amount of tear in the impression material. (4) Another approach is to block out the brackets on the stone model with another mix of dental stone prior to fabricating the mouth guard. (5)

Types of Mouth Guards

A mouth guard is a protective appliance that covers the teeth and palate and fits to the depth of the vestibule. (6) This definition is generic and universal, and includes a range of products from over-the-counter models sold in sporting goods stores to professionally manufactured and dentist-prescribed custom-made mouth guards. There are four categories or types of mouth guards currently available today, including:

* Stock Type: "One size fits all," purchased over-the-counter, inexpensive, offers the least protection;

* Mouth-Formed or Boil and Bite: User formed, purchased over-the-counter, inexpensive, offer little protection;

* Custom Vacuum-Formed Single Layer: Fabricated in the dental office, custom fit, moderately expensive, provides good protection; and

* Pressure Laminated Multiple Layer: Fabricated in the dental laboratory, custom fit, expensive, provides the best protection.

Stock-Type Mouth Guard

Stock-type mouth guards are the least expensive of the four types and offer the least amount of protection. They can be found in most sporting goods stores and come in limited sizes, usually small, medium, and large. The range in price is approximately $3 to $25, and the guards are ready-to-wear upon purchase. These protectors are bulky and lack retention and are held in place by constantly biting down. Athletes using stock-type mouth guards usually experience difficulty in breathing, speaking and gagging. (7) Because of these shortcomings athletes alter and cut these protectors in an attempt to make them more comfortable, thereby further reducing the protective qualities. (7) Dental practitioners should advise clients that these stock-type mouth guards are not to be worn because of their lack of retention and protective properties.

Mouth-Formed or Boil and Bite

Like the stock-type mouth guards, boil and bite mouth guards can be purchased in most sporting goods stores and come in limited sizes. Currently, the boil and bite mouth guard is the most commonly used in the market. Over 90% of the mouth guards worn are of the variety bought at sporting goods stores and the remaining 10% are custom made by a health professional. Mouth-formed mouth guards are thermoplastic and they are immersed in boiling water and formed in the mouth using fingers, the tongue, and biting pressure. Like the stock type, boil and bite mouth guards are bulky and lack retention, therefore athletes are likely to experience difficulties in breathing and speaking and will probably find themselves gagging. Athletes also alter and cut these protectors thus reducing the protective properties. For most high school and collegiate athletes, most boil and bite mouth guards do not cover all posterior teeth and tend to have bite-through issues during formation. (5) This increases the chance of life-long effects from injury, especially concussion as a result of a blow to the chin. Protection is minimal with this type of mouth guard, but it is still slightly better than wearing no mouth guard. (8)

Custom Vacuum-Formed Single Layer

Custom-made mouth guards are considered the best when compared to stock-type and mouth-formed boil and bite mouthguards. (9) They offer more protection because of the close adaptation of the mouth guard to the athlete's dentition and intraoral anatomical structures. (8) This type of mouth guard gives the dental practitioner the ability and flexibility to address the important issues in its fitting, for example, adaptation, retention, comfort, and stability of the material, ease of breathing and speaking, as well as acceptance. Custom-fitted mouth guards also do not need a strap attachment; they are contraindicated because of their superior fit. (5)

Pressure Laminated Multiple Layer

Pressure laminated multiple layer mouth guards are fabricated at a dental office or commercial laboratory. This type of mouth guard can be modified for full contact sports by laminating two or three layers of polyethylene vinyl acetate-EVA copolymer material to achieve the necessary thickness. Pressure laminated mouth guards are more expensive than the custom vacuum single layer mouth guards; however, they provide the best protection and are recommended for full contact sports, especially since they can be fitted according to the athlete's sport.

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Custom fitted mouth guards should fit over one arch covering all teeth, using the maxillary arch for class I and II malocclusion and the mandibular arch for class III malocclusion. (5) When fabricating a mouth guard it is suggested that the labial thickness be at least three mm, with a palatal thickness of two mm, occlusal thickness of three mm and extension into the vestibular borders with three mm short of the labial fold. (10) Darby recommends that pressure laminated mouth guards should be based on the client's degree of risk. (6) Following is a description of Darby's recommendation:

Light: two layers approximately two mm thick;

Medium: two layers approximately five mm thick;

Heavy: two layers approximately five mm thick with power dispersion strips; or

Heavy Pro: three layers approximately five mm thick with a hard support.

When fabricating a custom-made single layer or multiple layer mouth guard, there are five stages to the fabrication:

1. Preseason or dental examination

2. Impression and model

3. Fabrication

4. Trimming

5. Delivery

Preseason or Dental Examination

Custom mouth guards give the dental practitioner the ability to address important issues in the fitting of the mouth guard. Several questions must be answered before the custom mouth guard can be fabricated. (11) These questions include those addressed at the preseason screening or dental examination. Is the mouth guard designed for the particular sport being played? Are the age of the athlete and the possibility of providing space for erupting teeth in the mixed dentition (age 6-12) going to affect the mouth guard? Will the design of the mouth guard be appropriate for the level of competition being played? Does the patient have any history of previous dental injury or concussion, thus requiring additional protection in any specific area? Is the athlete undergoing orthodontic treatment? Does the patient present with cavities and/or missing teeth? These are just several questions that should be included in the dental practitioner dental exam that will aid in providing the best care and quality of mouth guard.

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Impression and Model

Alginate material is used for the impression and it is important to cover all anatomical structures, especially all teeth in the arch and vestibular regions. A poor impression of the arch can lead to a poor model, resulting in a poorly made mouth guard. Type III dental stone can be used for pouring up the cast. The dental practitioner should make sure all anatomical features are captured. A base or art portion of the cast is not necessary. Inspect the cast and remove any bumps or blebs of dental stone on the teeth or on the anatomical portion. After the cast has hardened, it should be trimmed carefully to include the vestibular borders (Figure 1). It is important to maintain the vestibular borders to allow for the mouth guard design to extend into these areas, increasing surface adaptation, which increases retention and protection of the alveolar bone. (12) The cast is then allowed to dry.

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Fabrication

The material of choice for custom made mouth guards is a laminated poly ethylene vinyl acetate (EVA) copolymer material. Insert a sheet of the EVA material in the frame of the vacuum former and clamp it in place. Lift the clamping frame up to the heating element and turn on the heat to soften the material. Place the maxillary cast or mandibular cast for class III mal-occlusion on the platform and center it under the sheet of EVA material. The EVA material is heated until it sags or droops about one inch and is then lowered onto the cast (Figure 2). Turn on the vacuum when the molten tray material covers the cast and let it stand for at least 30 seconds to ensure proper adaptation. If air is trapped between the cast and the EVA material, use a damp paper towel to help form and adapt the mouth guard material to the cast while the vacuum is still on (Figure 3). The cast and mouth guard are then removed from the vacuum former to allow cooling.

A pressure laminated multiple layered mouth guard is defined as the layering of mouth guard material to achieve a defined end result and thickness under a high heat and high pressure environment. Efficient and complete lamination cannot be achieved under low heat and vacuum. The layers will not properly fuse together with the vacuum machine, but will chemically fuse under high heat and pressure with machines such as the Drufomat, the Erkopress 2004, or the Biostar. It is recommended that the dental practitioner use a commercial laboratory for fabrication of the multiple layered mouth guard.

Trimming

Once the mouth guard is cooled, cut the gross excess material from the depth of the periphery of the cast using heavy trimming utility scissors. Remove the mouth guard from the cast and trim using a small, sharp crown and collar scissors. Make sure to follow the vestibular border with approximately three mm from the labial fold and locations of the frenum attachments. On the palatal region the mouth guard should extend minimally one mm or three-eighths of an inch and distally at

least up to the second molar. To enhance the client's comfort, the margins of the mouth guard are trimmed using an acrylic burr or feathered with a finishing wheel on a lathe. To smooth the borders and occlusal surface use a torch or flame to soften the material, then lightly rub the surface of the EVA with a gloved finger coated with petroleum jelly.

[FIGURE 4 OMITTED]

Delivery

Upon delivery of the mouth guard it should be tried in the patient to check for fit, retention, comfort and acceptance. The vestibular region and frenum attachments must be checked with at least three mm from the labial fold to ensure movement and fit (Figure 4). All adjustments should be made and completed at this appointment time. To ensure proper occlusion in the molar region, slightly warm the occlusal with a torch and then place it back in the patient's mouth. Instruct the patient to bite lightly into the mouth guard. However, the dental practitioner must be aware not to reduce the minimal occlusal thickness to less than three mm. The final step in the delivery process is to inform and instruct the patient on proper home care of the mouth guard, as follows:

1. Before and after using the mouth guard, it should be rinsed and washed with cold or luke-warm water to remove saliva build-up, bacteria, debris, and to minimize discoloration;

2. To avoid distortion of the mouth guard do not scrub with an abrasive dentifrice. Do not use hot water, alcohol solutions, or denture cleansers to clean;

3. Nonabrasive toothpaste on a soft-bristle toothbrush and rinses with nonalcohol mouthwash are permissible;

4. Do not store mouth guard in water or any solution. Simply store the mouth guard in an empty, protective plastic appliance container;

5. The mouth guard should be checked periodically for distortions, tears, or bite-through. (5)

Once these instructions are followed by the athlete, the mouth guard should be usable for at least two seasons. After that period of time passes, it is highly recommended that a new mouth guard be fabricated. (8)

Conclusion

A properly diagnosed, designed, and custom-fabricated mouth guard is important in preventing or reducing severity of concussions as well as minimizing oral cavity injuries. A properly fitted mouth guard must be protective, comfortable, resilient, tear resistant, odorless, tasteless, and not bulky. Furthermore, it should only cause minimal interference with speaking and breathing. Most importantly, the mouth guard should have excellent retention, fit, and sufficient thickness in critical areas. Although 90 percent of mouth guards are over-the-counter stock-type or boil and bite variety, the perception that these are the only available mouth protectors is false. (11) The dental practitioner plays an imperative role in preventing orofacial injuries by educating patients, parents, coaches and trainers on the importance of using a custom-fitted mouth guard.

References

(1.) Flanders Raymond A Mohandas BHAT, The Incidence of Oro Facial Injuries in Sport--A Pilot Study in Illinois, JADA, Vol 126, April 1995, pp 491-96.

(2.) Fact Sheet. Needham MA: National Youth Sports Safety Foundation; 1994.

(3.) Diab N & Mourino AP. Parental attitudes toward mouth guards. Pediatric Dentistry. 1997; 19(8):455-60.

(4.) Croll TP, Castaldi CR. Custom sports mouth guard modified for orthodontic patients and children in the transitional dentition. Pediatr Dent. 2004;26:417-420.

(5.) Ranalli DN. Prevention of sports-related traumatic dental injuries. Dent Clin North Am. 2000; 44:35-51.

(6.) Darby ML, Walsh, MM. Dental Hygiene Theory and Practice 2nd ed. Saunders 2003; 21-22, 59-73. Philadelphia.

(7.) Gardiner DM, Ranalli DN. Attitudinal factors influencing mouth guard utilization. Dent Clin North Am. 2000;44:53-56.

(8.) Chi, HH. Properly fitted custom-made mouth guards. Compendium 2007;28(1):36-41.

(9.) Ranalli DN, Demas PN. Orofacial injuries from sport: preventive measures for sports medicine. Sports Med. 2002;32:409-418.

(10.) Craig RG, Powers JM, Wataha JC. Dental Materials: Properties and Manipulation 8th ed. Mosby 2004;51-59.

(11.) http://www.sportsdentistry.com/mouthguards.html. Sports Dentistry Online-Athletic Mouth Guards.

(12.) Padilla RR, Felsenfeld AL. Treatment and prevention of alveolar fractures and related injuries. J Cranio-maxillofac Trauma. 1997;3:22-27.

Elvir Dincer, DDS, is an Assistant Professor of Dental Hygiene at CUNY-Eugenio Maria de Hostos Community College in Bronx, NY, USA and is the supervising dentist in the program. He is currently a member of American Dental Association, New York State Dental Association and Queens County Dental Society. He is also a consultant member of the North East Regional Board of Dental Examiners. [e-mail].

Salim Rayman, RDH, BS, MPA, is an Assistant Professor at CUNY-Eugenio Maria De Hostos Community College in Bronx, NY, USA. He received an Associates degree in dental hygiene at SUNY-Farmingdale in Farmingdale, NY, a bachelors degree in Health Education and a masters degree in Public Administration from New York University in New York City. [e-mail].

By Elvir Dincer, DDS, and Salim Rayman, RDH, BS, MPA