Definition of Mouthguard:
The ASTM (American Society for Testing and Materials) defined athletic mouthguard as a resilient device or appliance placed inside the mouth (or inside and outside) to reduce mouth injuries particularly to the teeth and surrounding structures.
The ASD (Academy for Sports Dentistry) statement on “A Properly Fitted Mouthguard”. In this statement, the ASD adopted the ASTM operational definition for a mouthguard. The ASD statement goes further to state that the single word “mouthguard” must be replaced by the terminology “properly fitted mouthguard”.
Functions of mouthguards:
- They spread the force of the blow over all the teeth that are covered by the mouthguard.
- They stop violent contact of the upper & lower teeth.
- They keep the lips away from the malaligned teeth protecting the lips, the teeth and an orthodontic treatment.
- They hold the jaws apart:
- acting as shock absorbers.
- preventing upward & backward displacement of the condyles in their fossae.
So, they may reduce the incidence of concussion from a blow to the chin.
Types of mouthguards:
- Stock Mouthguards:
The stock mouthguards, available at most sporting goods stores, come in limited sizes (usually small, medium, and large), least expensive but the least protective. As they cannot be prepared to mimic the mouth, they fit poorly, bulky, interfere with talking and breathing and can be held in place only when the jaws are closed. Some athletes try to make it more comfortable by cutting parts of their stock mouthguard that further reduces the required retention and protection. Unfortunately, these are still the most commonly used mouthguards on the market of many developing countries.
Ranalli, 1991, consider stock mouthguards to be potentially hazardous and should not be recommended.
- Mouth Formed Mouthguards:Presently, most mouthguards sold worldwide are of this type. They are available in limited sizes and are of two subtypes: the shell-liner and the thermoplastic.
- a) The shell-liner type: consists of a preformed outer shell of polyvinyl chloride that fits loosely over the maxillary dentition. The liner is made of a plasticized acrylic gel or a silicon rubber. This mixture is placed in the player’s mouth, permitted to mold to the teeth, and then thermoset or chemoset. Because the outer shell is a stock tray resembling the stock mouthguards in size, they are also bulky and interfere with breathing and talking.
The shell-liner type
Heintz, 1968, and Bureau of Health Education and Audiovisual Services, and Council on Dental Materials, Instruments, and Equipment, 1984, found that by repeated biting on the shell liner mouthguards the liner material crept or spread, resulting in decrease in retention. Moreover, as the material is continually exposed to oral fluids, the plasticizers are leached out causing the liner to become hard. This in turn further reduces the protective properties of these mouthguards.
b) The thermoplastic type (boil and bite mouthguards): made from thermoplastic copolymer of polyvinyl acetate-ploy ethylene, immersed in boiling water for about 45 seconds, dipped in cold water for a few seconds and formed in the mouth by using finger, tongue, and biting pressure.
Woodmansey, 1999, added that because these mouth guards are formed at near-body temperatures, it has been reported that they can readily distort and wear through. Moreover, these mouthguards often lack proper thicknesses and extensions. So, they do not cover the needed area with the appropriate thickness on the posterior teeth leading to lesser protection and retention. Moreover, athletes usually try to alter thicknesses and extensions to get more comfort that further reduces the required retention and protection. In one reported incident in Australia, a boil-and-bite mouth guard dislodged from the teeth and impacted in an athlete’s oropharynx.
Tawfik and Moselhy, 2001, as many other researchers all over the world found that Custom Mouthguards are still superior to the Stock and Mouth Formed Mouthguards because they have a better fit and retention, thickness, comfort, life span and ease of breathing and talking.
For more than 30 years of experience dealing with athletes and athletic injuries, I found that Stock and Mouth Formed Mouthguards do not provide the expected comfort and injury protection that Custom Made Mouthguards do. Additionally, most of the athletic community believe that mouthguards are uncomfortable, unretentive, bulky, interfere with talking and breathing and introduce gagging simply because most mouthguards worn are of the Stock and Mouth Formed Mouthguards and the majority of athletes do not wear Custom Made Mouthguards provided by the dentist.
So, as a sports dentist, I do not recommend both Stock and Mouth Formed Mouthguards to my patients and athletic teams.
- Custom Made Mouthguards:
As they are made by the dentist, they are the most expensive, but are the best from the standpoint of fit, retention, comfort, and ease of speech. This type is fabricated on a cast of athlete maxillary dentition and surrounding tissues. Before fabrication of the Custom Made Mouthguard, your dentist will address medical and dental history, conduct thorough oral and para-oral examination and may conduct other investigations as taking necessary x-rays. Many factors should be considered before the Custom Mouthguard fabrication because they may affect the mouthguard fabrication technique and design. These may include general and personal factors as:
- Type of sport and level of competition being played.
- Position of the player e.g. goalkeeper, wing, …etc. Moreover, famous athletes usually are more vulnerable to sports injuries due to intentional or unintentional tough play of opponents.
- Previous history of dento-facial injuries or concussion thus needing additional protection in any specific area.
- Age of the athlete as young athletes at the mixed dentition period (approximately 6-12 years old) should be supplied with mouthguard that provide adequate space for the developing jaw and the erupting teeth or sometimes mouthguard replacement.
- Gender of the athlete as females practicing sports are less prone to vigorous injuries than males. Additionally, females usually like some feminine touches added to their mouthguards.
- Type of occlusion as some athletes close their teeth in a way that need the fabrication of mouthguard on their lower jaw instead of the upper jaw or even the fabrication of what is called Bimaxillary Mouthguard on both jaws.
- Athletes who are under orthodontic treatment need special technique for mouthguard fabrication and recurrent replacements primary to protect their teeth and soft tissues (e.g. lips and cheek) from laceration or abrasions by either the orthodontic bands and/or wires and secondary to protect the orthodontic treatment itself.
- Athletes presented with cavities, impacted teeth as canines, missing teeth and/or removable or fixed prosthesis would have special professional attention.
- Mouthguard colors should be picked in harmony with the athlete’s complexion, colors of his/her hair and eyes …etc. Moreover, it may carry names, team logo or country flag.
- Athletes’ desires as some sportsmen like some colors that emotionally affect their performance or their opponents’ performance.
These are some important factors that only the well-experienced sports dentist would consider before fabrication of Custom Made Mouthguard to athletes.
Recently, custom made mouthguards may be classified into four types:
First, Injection Molded Mouthguards that are laboratory fabricated using lost wax injection molding techniques as urethane or rubber materials. This type of mouthguards is usually made in selected cases as in fabrication of Bimaxillary Mouthguards.
Second, Vacuum-Formed Mouthguards constructed of ethylene vinyl acetate (EVA) sheets, which are heated in a vacuum-forming machine and then adapted to a stone model with negative pressure.
Preci-Vac and Easy-Vac are just examples of good vacuum forming machines that I had used in fabrication of mouthguards.
Third, Pressure-Laminated Mouthguards, which are, considered the best mouthguards available. These are fabricated from sheets of laminated EVA materials and multiple layers of protective materials can be fused together to form an adequately thick and protective mouthguard with specialized machines that apply high heat and pressure. Drufomat Scan, Erkopress-2004 and Biostar are examples of these machines.
Fourth, 3D Printed Mouthguards, these are fabricated by either:
- An intraoral optical impression taken intra-orally by a scanner.
- An extra-oral scanning of a poured stone cast obtained by an accurate impression taken from the athlete.
Then, by a special program, the mouthguard is virtually designed. The data of fabrication of the mouthguard is finally processed very accurately by 3D printer.
As the thermo-forming techniques for fabrication of custom made mouthguards (Vacuum-Formed and Pressure-Laminated Mouthguards) are still the most popular all over the world, we will discuss them in more detailed manner:
Material of choice for mouthguards’ fabrication:
EVA (Ethylene Vinyl Acetate) has been shown to exhibit desirable properties for use in mouthguards, such as non-toxicity, minimal moisture absorption, elasticity, and ease of manufacture.
Raintree Essix, Inc., New Orleans, USA.
Proform, Dental Resources, Inc., Delano, USA.
Examples of EVA products
Ranalli, 2000, found that although the vacuum-forming machine uses 1 atm. or less of pressure to vacuum the EVA material down over the dental cast, the heat pressure-laminating machine uses a positive pressure of 10 atm. to pressure form the EVA material over the dental cast. Moreover, this technique offers the added capability of fusing multiple layers (lamination) of EVA material to the desired thickness to meet the needs of the individual athlete.
Fabrication of Custom Made Mouthguards from EVA blanks:
- Your dentist will take an impression (mold) of the upper jaw and sometimes both jaws and then poured in stone. Alginate impression material is adequate. However, rubber base impression would be preferred, if pouring more than one stone cast is targeted.
Impression on stock tray with alginate
Impression on special tray with rubber base
An impression (mold) of the upper jaw
Stone cast is hollowed or better furrowed with vacuum formed mouthguards.
On the other hand, pressure laminated mouthguard doesn’t need this modification in the cast.
- The vinyl blank is placed in either the vacuum forming machine or heat pressure laminating machine and heated until it becomes pliable and starts to sag within the frame. The frame is then lowered over the cast. The vacuum or the pressure is turned on and the material is adapted to the cast.
- The blanks thickness (usually 3.6 mm) will not remain the same due to shrinkage during fabrication. So, for optimal protection, addition of extra layers is performed according to the required design. As mentioned before, this design may be changed according to the athletes’ individual variations that could accurately made by heat pressure laminating machine. This will allow incorporating two or more EVA material to achieve the required thickness.
- After allowing for the material to cool, the cast and mouthguard are removed from the machine. The mouthguard is trimmed so it extends to approximately two millimeters short of the mucobuccal fold with clearance for the buccal and labial frenum areas provided by notching the mouthguard in these areas. In most of the cases, mouthguard is extended as far distally as the second bicuspids or first molars and sometimes the second molar.
- With the mouthguard trimmed in this manner the athlete can speak normally, drink water, chew gum and breathe easily.
Outline marked on the cast
After trimming according the outline
Trimming, grinding and final finishing of margins of the mouthguard by the butane torch
- Equalization of the occlusion with the mouthguard in place could be accomplished by warming the occlusal surface of the mouthguard with an alcohol torch, tempering the protector in warm water, placing the protector in the athlete’s mouth, and having the athlete close gently until all the teeth contact the mouthguard. The mouthguard is removed, allowed to cool, and then replaced in the mouth for reexamination of the occlusion. The mouthguard should not be overheated as this could cause distortion and a poor fit.
Equalization of the mouthguard’s occlusion
- The athlete’s name or number could be placed in the mouthguard as follows: the player’s last name and initial were typed on paper and trimmed with scissors; the mouthguard was placed on the cast, one buccal flange of the mouthguard was softened with an alcohol torch, and the trimmed paper was impressed into the softened resin with a plugger. Then, a small strip of scrap mouthguard material, 2 mm by 15 mm, was trimmed and softened above a flame; the softened material was adapted over the impressed paper with lubricated fingers to carefully mold the material and seal the name within the mouthguard; the excess material was trimmed with a stone to restore contour; and the area was flamed lightly to improve the transparency of the resin. However, Yonehata and Maeda, 1999, described a fast, effective and inexpensive way of marking an EVA mouthguard with personal identification using a stamp and torch.
Scott et al., 1994, recommended the mouthguard design as follows:
- It should cover the maxillary teeth till the distal surface of the upper second molar.
- Thickness should be different:
- On the labial aspects = 3 mm
- On the occlusal aspect = 2 mm
- On the palatal aspect = 1 mm.
- The labial flange should extend to within 2 mm of the vestibular reflection.
- The palatal flange should extend about 10 mm above the gingival margin.
- The edge of the flanges:
- The labial flange should be rounded in cross section
- The palatal edge should be tapered.
- For optimum comfort, maxillary mouthguard should be mounted on the articulator against the matching mandibular model. mounting is recommended in all cases, even when a single maxillary mouthguard is constructed
In another study, Greasly et al., 1998, recommended that the following guidelines should be added to Scott and his colleagues’ design:
- Multiple layers of EVA should be utilized. to build a 5 mm thick layer in the thicker parts of a custom made protector
- A 9 mm labial flange should be incorporated where flexible.
- The protector should be extended to at least behind the first molar or as far along the second molar to provide wearer comfort.
- The palatal flange should be designed to provide wearer comfort.
- Air pockets or cushioning devices should not be incorporated as no beneficial effects can be expected from them.
- Incorporation of stiff and hard layers should not be used as no benefits occur in terms of broken teeth.
McClelland et al., 1999, conducted a preliminary study of patient comfort associated with customized mouthguards. They concluded that comfort is likely to be increased if mouthguards are extended labially to within 2 mm of the vestibular reflection, adjusted to allow even occlusal contact, rounded at the buccal peripheries, and tapered to the palatal edges.
As a sports dentist, I recommend Custom Made Mouthguards to my athletes.
Finished Custom Made Mouthguards in place
TO BE CONTINUED …
UNDER RE-CONSTRUCTION …