Towards the development of a standard test procedure for mouthguard assessment

Sports mouthguard overview: Materials, fabrication techniques, existing standards, and future research needs

Sports mouthguards are proven devices that reduce both the probability of and damage to orofacial tissues. While commonly used, clinicians may be unaware of the different sports mouthguard materials, proposed fabrication techniques, design recommendations, and newer digital fabrication methods. An overview of existing sports mouthguard standards is presented. It identifies that identify that the present requirements, while historically chosen in good faith, appear to be arbitrarily selected and not from clinical evidence-based derived data. In addition, identified sports mouthguard heterogeneous testing and data acquisition methods distinguishes that little possibility is afforded for the correlation of results. Furthermore, updated evidence with concussion prevention and/or alleviation is presented with evidence provided by sports mouthguard imbedded technology. The need for continued research is stressed to provide evidence-based data for concussion alleviation/prevention, digital fabrication methods and materials, and clinically based information for the revision of existing standards.

A Novel Method for the Mechanical Testing of Sports Mouthguards

Current mouthguard test methods require improvement, as the impact energies during traditional testing do not reflect the higher energy that can be observed in actual use during sport. A new data set of ball speeds experienced during the sport of field hockey was obtained. These ball speeds have then been used to estimate impact energies. This information was used to subsequently develop a new test method consisting of a high-speed camera and drop tower. Observations show an increase in energy experienced by the mouthguard for higher-impact energies. The work carried out showed that current testing methods for sports mouthguards use lower-energy impacts than experienced during the sport of field hockey. The new method that is proposed allows for a more realistic representation of real-world impacts.

What are the differences in protective characteristics of orthodontic mouthguards? An in vitro study

BACKGROUND

Orthodontic patients wearing fixed appliances are susceptible to traumatic dental injuries during contact-sport. This laboratory study investigated the protective qualities of orthodontic mouthguards using impact-testing to a typodont fitted with a fixed appliance through peak load transfer and retention of the mouthguard.

METHODS

Seven orthodontic mouthguards [three custom-made (Medium-CM, Heavy-CM, Heavy-pro-CM); three commercially-available mouth-formed (Shock-Doctor® Ultra Braces, Opro® Ortho-Gold Braces, Opro® Ortho-Bronze Braces) and a Shock-Doctor® Instant-Fit] were fitted to a maxillary arch typodont bonded with a fixed appliance and impact-tested using 0.5 or 1 Joule (J) energy via hockey-ball, cricket-ball or steel-ball projectile. A load-cell recorded peak load transfer through mouthguard to typodont with retention scored in a binary manner dependent upon any displacement following impact. Differences across mouthguards were calculated with ANOVA or Kruskal-Wallis test for normal and non-normal data, respectively. Post hoc comparisons across mouthguards were conducted via Dunnett's test with Sidak correction.

RESULTS

Only the three custom-made and Opro® Ortho-Gold Braces were not displaced by impact-testing. For these, Opro® Ortho-Gold Braces transferred the smallest load for 3/6 impact-tests, followed by Medium-CM. Heavy-pro-CM performed poorly, ranking penultimate or worst for all impact-tests. Significant differences were found between mouthguards for cricket-ball and steel-ball set-ups. The Opro® Ortho-Gold Braces performed better than the Heavy and Heavy-pro-CM for 0.5 J cricket-ball impact-test (P < 0.05), whilst Medium-CM performed better than Heavy-pro-CM. For 1 J cricket-ball, there were significant differences between Medium-CM and Heavy-pro-CM (P < 0.05). For 0.5 J steel-ball, the Medium-CM performed significantly better than both Heavy-pro-CM and Opro® Ortho-Gold Braces (P < 0.05), whilst Heavy-CM performed better than the Heavy-pro-CM (P < 0.05). For the 1 J steel-ball, Medium and Heavy-CM performed better than Opro® Ortho-Gold Braces (P < 0.05).

CONCLUSIONS

Opro® Ortho-Gold and Medium-CM mouthguards offer the best protection for low-impact sports, whilst Medium or Heavy-CM mouthguards are recommended for high-impact sport.

Wearability and preference of mouthguard during sport in patients undergoing orthodontic treatment with fixed appliances: a randomized clinical trial

Background

Orthodontic patients wearing fixed appliances are susceptible to traumatic dental injuries during a wide range of sporting activities. This randomized clinical trial investigated wearability and preference of mouthguards during sporting activities in patients undergoing orthodontic treatment with fixed appliances.

Methods

A prospective three-arm crossover randomized clinical trial conducted in the UK. Thirty patients in active orthodontic treatment with fixed appliances undertaking at least 120 minutes of contact sport per 6–8-week observation period were randomly assigned to one of six mouthguard allocation sequences consisting of three mouthguard types: (MG1) custom-made laboratory constructed, (MG2) mouth-formed OPRO® Gold Braces, and (MG3) pre-fabricated Shock Doctor® Single Brace. Patients completed a nine-outcome 100-mm visual analogue scale (VAS) questionnaire relating to mouthguard wearability during sport. Once feedback was completed, subjects were allocated the next mouthguard in the sequence. At study-end, subjects were asked to identify their preferred mouthguard.

Results

Twenty-four patients (median age = 13; inter-quartile range 12–14.5 years) completed n = 72 follow-up questionnaires with most playing rugby union or field hockey. Considering VAS score as a continuous variable, for comfort, stability, hardness, ability to breathe, ability to not cause nausea, and inclination to chew, MG2 performed better than MG3. For categorization of VAS score into low (less than 80 mm) or high (at least 80 mm) wearability, for comfort, stability, ability to not cause nausea, and inclination to chew, MG1 and MG2 also rated superior to MG3. Patients preferred MG1 overall.

Conclusions

This randomized clinical trial found that during contact sport patients in fixed appliances reported superior wearability for custom-made and mouth-formed mouthguards in comparison to pre-fabricated. Overall, patients preferred custom-made mouthguards.

Clinical trials registration

ClinicalTrials.gov: NCT04588831.

On the ability of experimental impact measures to predict tooth injuries in an ex vivo swine model

BACKGROUND/AIM

Impact to the orofacial region, in particular teeth, is a frequent incident leading to injury in many sports and can result in health and economic costs for the injured individual. The majority of previous work has applied synthetic models such as plaster or stone, to form analogs of relevant structures to study the potential for impact-induced injury. Biomechanical studies that have applied tissue models (animal or human) for the purpose of determining the biomechanical measures associated with dental injury are rare. The aim of this study was to apply a simple ex vivo model based on swine dentition to ascertain which of a select list of measurable quantities associated with impact mechanics could predict luxation and fracture of teeth due to impact.

METHODS

Mandibular central incisors of ex vivo swine dentitions were impacted using a linear drop tower with heights ranging from 1.20 m to 2.42 m. Seven mechanical predictors were assessed at impact and were then subjected to binary logistic regression techniques to determine which was the best predictor of luxations or fractures of the teeth.

RESULTS

Of the seven mechanical predictors, (1) the velocity of the impacting body (R²  = 0.477), (2) a proxy measure for the change in kinetic energy of the impacting body (R²  = 0.586), and (3) the approximate energy absorbed by the tissue (R²  = 0.722) were found to be statistically significantly different (p < .05), offering the greatest specificity as indicated by receiver operator characteristics. Other measures that are frequently used in impact mechanics, including peak linear acceleration and velocity change, were not statistically significant predictors of tooth injury.

CONCLUSION

Identifying mechanical predictors for dental injury of unprotected teeth provides a first step in understanding which aspects of an impact event attribute to dental injury and can lay the foundation for future studies that examine alteration in injury mechanics associated with protection devices.

Effectiveness and fabrication of mouthguards

Although mouthguards have been suggested as a means for preventing dental traumatic injuries, there are still some controversies over some aspects such as effectiveness in preventing concussions, material selections, method for fabrication, design, side effects and so on. The purpose of this literature review was to clarify differences in opinions with supporting evidence on these issues and find the best guidelines for promoting usage and providing mouthguards with better protective capability and fewer side effects such as difficulty in breathing and speaking.

Avaliação do conhecimento em odontologia e educação física acerca dos protetores bucais

Este estudo teve o propósito de avaliar o nível de conhecimento de 150 alunos de graduação dos cursos de Odontologia e Educação Física acerca dos protetores bucais no município de Belém, Brasil. Além disso, objetivou-se promover maior informação a esses futuros profissionais, por meio de palestras e distribuição de folders, nas quais o foco principal eram os protetores bucais, suas indicações, seus tipos, sua higienização e armazenamento. Os participantes da pesquisa pertenciam ao último ano de seus referidos cursos de graduação. A análise dos resultados permitiu evidenciar que 68% dos alunos entrevistados ainda não possuem informação adequada acerca dos protetores bucais, mas que, apesar disso, em sua maioria são conscientes quanto aos riscos a que vários atletas são submetidos em esportes que exigem impacto físico. Os autores acreditam que é extremamente importante que haja maior divulgação da importância da utilização de protetores bucais na prática esportiva, visando a prevenção e a promoção de saúde da população em geral.

Mouthguards in Sport Activities

Three systematic reviews were conducted on: (i) the history of mouthguard use in sports; (ii) mouthguard material and construction; and (iii) the effectiveness of mouthguards in preventing orofacial injuries and concussions. Retrieval databases and bibliographies were explored to find studies using specific key words for each topic. The first recorded use of mouthguards was by boxers, and in the 1920s professional boxing became the first sport to require mouthguards. Advocacy by the American Dental Association led to the mandating of mouthguards for US high school football in the 1962 season. Currently, the US National Collegiate Athletic Association requires mouthguards for four sports (ice hockey, lacrosse, field hockey and football). However, the American Dental Association recommends the use of mouthguards in 29 sports/exercise activities. Mouthguard properties measured in various studies included shock-absorbing capability, hardness, stiffness (indicative of protective capability), tensile strength, tear strength (indicative of durability) and water absorption. Materials used for mouthguards included: (i) polyvinylacetate-polyethylene or ethylene vinyl acetate (EVA) copolymer; (ii) polyvinylchloride; (iii) latex rubber; (iv) acrylic resin; and (v) polyurethane. Latex rubber was a popular material used in early mouthguards but it has lower shock absorbency, lower hardness and less tear and tensile strength than EVA or polyurethane. Among the more modern materials, none seems to stand out as superior to another since the characteristics of all the modern materials can be manipulated to provide a range of favourable characteristics. Impact studies have shown that compared with no mouthguard, mouthguards composed of many types of materials reduce the number of fractured teeth and head acceleration. In mouthguard design, consideration must be given to the nature of the collision (hard or soft objects) and characteristics of the mouth (e.g. brittle incisors, more rugged occusal surfaces of molars, soft gingiva). Laminates with different shock absorbing and stress distributing (stiffness) capability may be one way to accommodate these factors.Studies comparing mouthguard users with nonusers have examined different sports, employed a variety of study designs and used widely-varying injury case definitions. Prior to the 1980s, most studies exhibited relatively low methodological quality. Despite these issues, meta-analyses indicated that the risk of an orofacial sports injury was 1.6-1.9 times higher when a mouthguard was not worn. However, the evidence that mouthguards protect against concussion was inconsistent, and no conclusion regarding the effectiveness of mouthguards in preventing concussion can be drawn at present. Mouthguards should continue to be used in sport activities where there is significant risk of orofacial injury.

Scale of protection and the various types of sports mouthguard

OBJECTIVES

To present a grading system of the protection offered by various types of mouthguard, together with an indication of associated risks, in order to make athletes aware of the consequences of improper or no mouth protection.

METHODS

A review of the literature on mouthguards, mouthguard materials, and novel laminates for mouthguards was carried out as it was apparent that information on mouthguards was lacking. Studies on stock (or unfitted) mouthguards, mouth formed (boil and bite) mouthguards, and custom mouthguards are reviewed.

RESULTS

A scale of protection offered by various mouthguards and novel laminates has been produced, where 0 indicates no mouthguard and 10 indicates a custom made mouthguard offering excellent protection.

CONCLUSIONS

From work carried out on laminates and the manufacturing processes of mouthguards, it became apparent that information was lacking to enable athletes make informed decisions about the best oral protection for their chosen sport.

Attitudes of Central Collegiate Hockey Association Ice Hockey Players Toward Athletic Mouthguard Usage

OBJECTIVE

The purpose of this study was to examine Central Collegiate Hockey Association ice hockey players' attitudes regarding the use of athletic mouthguards and to determine the effects of mouthguard type, player position, education, and usage time with respect to attitudes.

METHODS

A questionnaire measuring players' attitudes toward mouthguards was sent to certified athletic trainers (ATC) responsible for providing healthcare coverage at 10 institutions of the Central Collegiate Hockey Association (CCHA). The ATC's distributed the surveys to all the players on their respective collegiate teams. Out of a total of 265 players listed on the roosters of the CCHA, one hundred and sixty five (62%) players returned the surveys, with 158 surveys used in the analyses (60%).

RESULTS

Approximately 13.3% of players (n=21) reported wearing mouthguards 50% of the time or greater during games and 3.8% (n=6) reported wearing mouthguards 50% of the time or greater during practices. Twenty-six percent (n=41) of the players never received educational information regarding using mouthguards. Thirty-nine percent (n=59) of the players reported altering mouthguards to obtain a better fit while 91% of the players were not influenced by the cost of the mouthguard. A 2 x 2 x 2 ANOVA revealed a significant interaction among player position and mouthguard type with respect to player attitudes (F(1,131) = 4.96, P < 0.05), with defensive players having more negative attitudes toward mouthguard usage compared to offensive players.

CONCLUSION

No one specific factor affecting attitudes was identified, however, players reported limited educational opportunities to learn about the effectiveness of mouthguards. Therefore, coaches, dentists, and healthcare providers should engage in more preventive educational programs to increase player attitudes and compliance.

Are all mouthguards the same and safe to use? The influence of occlusal supporting mouthguards in decreasing bone distortion and fractures

The safety benefits of mouthguards have been demonstrated in many studies, with many authors and sports dentists strongly recommending the wearing of mouthguards. However, wearing a mouthguard with incorrect occlusion might cause a variety of problems. It comes as no surprise that a traumatic blow to the chin, while wearing an insufficient mouthguard lacking anterior contact, can result in severe distortions to the mandibular bone, and bone fractures. The aim of this study was to clarify how ineffective insufficient occlusal supporting mouthguards are and how dangerous they can be to use. Consequently, in this study, occlusal supportive areas were varied and accelerations of head and distortions of the mandible were measured using an artificial skull model and a pendulum impact device. As a result, the distortions of the mandible tended to increase as the supported area decreased. On the contrary, accelerations of the head decreased as the occlusion part decreased. Thus, a lot of impact energy was consumed in the distortion of the mandible; accordingly, it seemed that only a little destructive energy was transferred to the head. From this study, it would seem that wearing a mouthguard, which is insufficient in the occlusion, has the potential of causing a bone fracture of the mandible. Consequently, mouthguards should have proper occlusion.

Sports dentistry and dental traumatology

Sports dentistry had its origins in the 1980s. More recently, the Academy for Sports Dentistry joined forces with the International Association of Dental Traumatology in cosponsoring the World Congress on Sports Dentistry and Dental Traumatology. It is the intent of the present paper to introduce readers to the arena of sports dentistry, suggest future areas for collaborative research, and stimulate authors to submit high quality, scientifically based manuscripts on sports dentistry to Dental Traumatology.

Transient forces generated by projectiles on variable quality mouthguards monitored by instrumented impact testing

OBJECTIVES

(a) To determine the force-time trace that occurs when a spring mounted simulated upper jaw is impacted; (b) to examine if mouthguards of variable quality have significant influence on such force-time traces; (c) to attempt to relate physical events to the profile of the force-time traces recorded.

METHODS

A simulated jaw, consisting of ceramic teeth inserted into a hard rubber arch reinforced with a composite jawbone, was fitted with various mouthguards as part of a previous round robin study. A clinical assessment distinguished good, bad, and poor mouthguards, and these were each fitted to the jaw, which was then submitted to instrumental impact tests under conditions expected to produce tooth fractures. The force-time trace was recorded for such impact events.

RESULTS

The spring mounting method caused two distinct peaks in the force-time trace. The initial one was related to inertia effects and showed an increase in magnitude with impactor velocity as expected. The second peak showed features that were related to the differences in the mouthguards selected.

CONCLUSIONS

The use of a force washer within a conical ended impactor enabled force-time traces to be recorded during the impact of a spring mounted simulated jaw fitted with mouthguards of variable quality. The spring mounting system causes an initial inertial peak followed by a second peak once the spring mount has fully compressed. Good fitting guards, which keep most teeth intact, result in high stiffness targets that in turn generate high reaction forces in the impactor. If the spring mounting is omitted, the two peaks are combined to give even higher reaction forces. The force-time trace offers some potential for assessing both overall mouthguard performance and individual events during the impact sequence. Mouthguards with good retention to the jaw remained attached during the impact event and helped to preserve the structural integrity of the target. This in turn developed high forces in the second part of the force-time trace. Guards that detached during impact and allowed tooth fractures showed lower forces in the second part of the test. The force profile measured offered some quantitative support to, and agreement with, the observed clinical quality of the mouthguards.

Mouthguard use in Australian football

A survey was performed of 961 Australian rules footballers of varying age and football ability in order to determine the prevalence of mouthguard use during training and match play. Emergency dental injury data was obtained to compare the frequency and timing of dental injury in a non-sporting community population. The prevalence of mouthguard use during match play varied between 60% for juniors and 90% for elite footballers whereas the mouthguard use during training ranged between 2% for junior and 40% for elite players. One third of players used over the counter 'boil & bite' mouthguards, generally considered unsatisfactory for dental protection. Of the players who did not currently use mouthguards, most had tried them previously but found them uncomfortable to wear. The community dental injury data showed that the majority of emergency dental injuries were due to sport and followed the temporal pattern of sports participation on week days and weekends. The prevalence of mouthguard use in this population was not known. This study has implications for the provision of emergency dental treatment for sport participants and for improved dental injury prevention measures to avoid expensive and potentially disfiguring dental injuries in young athletes.

Prevalence of dental trauma in 6000 patients with facial injuries: implications for prevention

OBJECTIVE

In contrast to epidemiologic studies on facial injuries reporting on dental trauma, facial bone fractures with dentoalveolar injuries, or soft tissue injuries individually, the purpose of this study was to evaluate the overall place of dental trauma in facial injuries. This was a retrospective investigation of the impact of sport, work, violence, traffic, household, and play accidents in the relationships among dental trauma, facial trauma, and other concomitant trauma. Finally, preventive considerations are discussed.

STUDY DESIGN

Six thousand patients registered at the University Hospital of Innsbruck's Department of Oral and Maxillofacial Surgery during a period of 6 years 4 months were admitted for dental trauma, facial trauma, or both. Records were analyzed for cause of injury, age, gender, monthly distribution, frequency, type of injury, and frequency of dental trauma in relation to facial injuries and concomitant injuries.

RESULTS

The incidence of dental injuries with respect to the total number of facial injuries was as follows: 57.8% in play and household accidents, 50.1% in sports accidents, 38.6% in accidents at work, 35.8% in acts of violence, 34.2% in traffic accidents, and 31% in unspecified accidents. The overall incidence revealed was 48.25%.

CONCLUSION

Our findings support the fact that in the mosaic of traumatic injuries, the frequencies of tooth trauma and its sequelae are underestimated and that such trauma and sequelae occur without a predictable pattern of intensity and extensiveness. Preventive approaches are the sole way to minimize the number of these injuries. Substantial progress made in treating facial and dental trauma in the last 2 decades only improves functional and esthetic outcomes among the population that has suffered dental injury.

Application of a standard test to the in vitro performance of mouthguards

OBJECTIVE

To use a simulated upper jaw made from a rubber arch containing replaceable ceramic teeth and a renewable composite ceramic jawbone to compare the effectiveness of seven custom made mouthguard designs and a "boil and bite" mouthguard.

METHODS

Following an earlier development of a standard impact test using a selection of projectile shapes and energies, the most sensitive conditions were selected. These were then applied to a series of six guards constructed in ethylene vinyl acetate and styrene butadiene. The guards were constructed to reflect possible variations in both design and materials.

RESULTS

Significant differences between the mouthguard performances were observed in response to the impact conditions selected. All the custom made designs gave better performance than the "boil and bite" mouthguard.

CONCLUSIONS

The differences observed indicated that the standard test should be sensitive enough to be used as an assessment procedure for the approval of the manufacture of these safety devices. A sequence of tests on eight identical mouthguards selected from a batch of 12, based on the best design, gave remarkably consistent results, indicating that both the manufacturing technique and the test method are reliable. The features of the best design should be incorporated into the current "best practice" for the construction of these devices.