Context

Current evidence regarding the protective effect of mouthguard use on symptom severity in children and adolescents who sustain sport-related concussions is insufficient to make clinical recommendations.

Objective

To compare the association between mouthguard use and symptoms stratified by sex in the first 4 weeks after pediatric sport-related concussion. We hypothesized that mouthguard use would be associated with less severe symptoms.

Design

Prospective cohort study.

Setting

Nine Canadian pediatric emergency departments (EDs).

Patients or Other Participants

Children aged 5 to 18 years who were assessed within 48 hours of concussions sustained during a collision or contact sport.

Main Outcome Measure(s)

Injury characteristics were collected using the Acute Concussion Evaluation. The primary outcome measure was symptom score (range = 0–6), measured using age-appropriate versions (5–7, 8–12, or 13–18 years) of the Post-Concussion Symptom Inventory. The independent variable was time postconcussion (initial assessment and 1, 2, and 4 weeks).

Results

Of 1019 children (73% male; median [interquartile range] age = 13.43 years [11.01–15.27 years]), 42% wore a mouthguard at the time of injury. No significant group-by-sex-by-time interaction was present for symptoms (⁠|$\(\def\upalpha{\unicode[Times]{x3B1}}\)\(\def\upbeta{\unicode[Times]{x3B2}}\)\(\def\upgamma{\unicode[Times]{x3B3}}\)\(\def\updelta{\unicode[Times]{x3B4}}\)\(\def\upvarepsilon{\unicode[Times]{x3B5}}\)\(\def\upzeta{\unicode[Times]{x3B6}}\)\(\def\upeta{\unicode[Times]{x3B7}}\)\(\def\uptheta{\unicode[Times]{x3B8}}\)\(\def\upiota{\unicode[Times]{x3B9}}\)\(\def\upkappa{\unicode[Times]{x3BA}}\)\(\def\uplambda{\unicode[Times]{x3BB}}\)\(\def\upmu{\unicode[Times]{x3BC}}\)\(\def\upnu{\unicode[Times]{x3BD}}\)\(\def\upxi{\unicode[Times]{x3BE}}\)\(\def\upomicron{\unicode[Times]{x3BF}}\)\(\def\uppi{\unicode[Times]{x3C0}}\)\(\def\uprho{\unicode[Times]{x3C1}}\)\(\def\upsigma{\unicode[Times]{x3C3}}\)\(\def\uptau{\unicode[Times]{x3C4}}\)\(\def\upupsilon{\unicode[Times]{x3C5}}\)\(\def\upphi{\unicode[Times]{x3C6}}\)\(\def\upchi{\unicode[Times]{x3C7}}\)\(\def\uppsy{\unicode[Times]{x3C8}}\)\(\def\upomega{\unicode[Times]{x3C9}}\)\(\def\bialpha{\boldsymbol{\alpha}}\)\(\def\bibeta{\boldsymbol{\beta}}\)\(\def\bigamma{\boldsymbol{\gamma}}\)\(\def\bidelta{\boldsymbol{\delta}}\)\(\def\bivarepsilon{\boldsymbol{\varepsilon}}\)\(\def\bizeta{\boldsymbol{\zeta}}\)\(\def\bieta{\boldsymbol{\eta}}\)\(\def\bitheta{\boldsymbol{\theta}}\)\(\def\biiota{\boldsymbol{\iota}}\)\(\def\bikappa{\boldsymbol{\kappa}}\)\(\def\bilambda{\boldsymbol{\lambda}}\)\(\def\bimu{\boldsymbol{\mu}}\)\(\def\binu{\boldsymbol{\nu}}\)\(\def\bixi{\boldsymbol{\xi}}\)\(\def\biomicron{\boldsymbol{\micron}}\)\(\def\bipi{\boldsymbol{\pi}}\)\(\def\birho{\boldsymbol{\rho}}\)\(\def\bisigma{\boldsymbol{\sigma}}\)\(\def\bitau{\boldsymbol{\tau}}\)\(\def\biupsilon{\boldsymbol{\upsilon}}\)\(\def\biphi{\boldsymbol{\phi}}\)\(\def\bichi{\boldsymbol{\chi}}\)\(\def\bipsy{\boldsymbol{\psy}}\)\(\def\biomega{\boldsymbol{\omega}}\)\(\def\bupalpha{\bf{\alpha}}\)\(\def\bupbeta{\bf{\beta}}\)\(\def\bupgamma{\bf{\gamma}}\)\(\def\bupdelta{\bf{\delta}}\)\(\def\bupvarepsilon{\bf{\varepsilon}}\)\(\def\bupzeta{\bf{\zeta}}\)\(\def\bupeta{\bf{\eta}}\)\(\def\buptheta{\bf{\theta}}\)\(\def\bupiota{\bf{\iota}}\)\(\def\bupkappa{\bf{\kappa}}\)\(\def\buplambda{\bf{\lambda}}\)\(\def\bupmu{\bf{\mu}}\)\(\def\bupnu{\bf{\nu}}\)\(\def\bupxi{\bf{\xi}}\)\(\def\bupomicron{\bf{\micron}}\)\(\def\buppi{\bf{\pi}}\)\(\def\buprho{\bf{\rho}}\)\(\def\bupsigma{\bf{\sigma}}\)\(\def\buptau{\bf{\tau}}\)\(\def\bupupsilon{\bf{\upsilon}}\)\(\def\bupphi{\bf{\phi}}\)\(\def\bupchi{\bf{\chi}}\)\(\def\buppsy{\bf{\psy}}\)\(\def\bupomega{\bf{\omega}}\)\(\def\bGamma{\bf{\Gamma}}\)\(\def\bDelta{\bf{\Delta}}\)\(\def\bTheta{\bf{\Theta}}\)\(\def\bLambda{\bf{\Lambda}}\)\(\def\bXi{\bf{\Xi}}\)\(\def\bPi{\bf{\Pi}}\)\(\def\bSigma{\bf{\Sigma}}\)\(\def\bPhi{\bf{\Phi}}\)\(\def\bPsi{\bf{\Psi}}\)\(\def\bOmega{\bf{\Omega}}\)\({\rm{\chi }}_3^2\)$| = 0.27; P = .965). Male mouthguard users reported similar symptom scores in the ED (difference in Post-Concussion Symptom Inventory Δ scores [diff] = −0.07; 95% CI = −0.23, 0.09) and at weeks 1 (diff = −0.02; 95% CI = −0.18, 0.14), 2 (diff = −0.03; 95% CI = −0.19, 0.13), and 4 (diff = −0.13; 95% CI = −0.29, 0.04) compared with males who did not wear a mouthguard. Female mouthguard users described minimally higher symptom scores at week 1 compared with non-mouthguard users (diff = 0.29; 95% CI = 0.01, 0.56). In the ED, symptom scores were not different for females who wore a mouthguard and those who did not (diff = 0.22; 95% CI = −0.04, 0.48) or at weeks 2 (diff = 0.22; 95% CI = −0.06, 0.51) or 4 (diff = 0.08; 95% CI = −0.20, 0.36).

Conclusions

Wearing a mouthguard at the time of injury was not associated with reduced acute or subacute symptoms after sport-related concussion in either males or females who were treated in the ED compared with those who did not wear a mouthguard. Athletes are still encouraged to wear mouthguards during sports because overwhelming evidence supports their use in preventing dental injuries.

Key Points
  • Mouthguard use did not protect against concussion symptoms in the first month after a sport-related concussion among children presenting to an emergency department.

  • Males wore mouthguards more often than females did.

  • Mouthguard use was not associated with sex-specific differences in postconcussion symptoms.

Sports are a leading cause of injury in youth, resulting in 1 to 2 million sport- and recreation-related concussions and accounting for roughly one-quarter of a million concussion-related visits to US emergency departments (EDs) every year.1,2  Several US and Canadian sporting organizations (ie, football, ice hockey, lacrosse, field hockey, and boxing organizations) have mandated the use of mouthguards in an attempt to prevent injuries.3  Although the ability of mouthguards to prevent dental injury has been well established,4,5  it remains unclear whether mouthguards prevent concussion in contact sports and whether various mouthguard types may be more effective in reducing risk.68 

The association between mouthguard use and the concussion-symptom burden after a sport-related concussion (SRC) is similarly ambiguous. Contradictory evidence9,10  exists as to whether wearing a mouthguard reduces the number of practices and games missed by hockey and football players because of concussion. Although the researchers9  of a large prospective study suggested that mean symptom severity may be less in professional hockey players who wear mouthguards, the authors11  of a small retrospective study in adolescents found that mouthguards did not reduce acute symptoms after concussion.

Existing concussion-severity studies have been limited by factors including study quality (retrospective design, abstract only),9,11  inconsistent definitions of concussion,10,11  assessing game exposure only,9  failure to report return-to-sport criteria,9  adjusting for confounding variables,9  and non–developmentally appropriate symptom scales.11  Investigations have predominantly addressed male, elite, adolescent, collegiate, or professional athletes without sex-based reporting, making it difficult to apply the results to nonelite or female athletes. Ultimately, large prospective studies are needed to assess any protective effect against SRCs so that appropriate recommendations can be made regarding the use of mouthguards in youth.

Current evidence regarding the protective effect of mouthguard use on symptom severity in children and adolescents who sustained SRCs is insufficient to make clinical recommendations. Therefore, our primary objective was to compare the association between mouthguard use and symptom score stratified by sex at acute presentation and 1, 2, and 4 weeks after pediatric SRC. We hypothesized that symptom severity would be lower in children and adolescents who wore mouthguards at the time of concussion compared with those who did not but that no difference would be seen between males and females.

Study Design and Setting

This work is a secondary analysis of the Predicting and Preventing Postconcussive Problems in Pediatrics (5P) study,12,13  a prospective, multicenter cohort investigation. Participants were recruited between August 2013 and June 2015 from 9 Pediatric Emergency Research Canada Network (PERC) tertiary pediatric EDs. The research ethics committees at each participating institution approved the study.

Patients

We recruited patients aged 5 to 18 years who presented to the ED within 48 hours of head injury and were diagnosed with a concussion according to the Zurich Consensus Statement on Concussion in Sport.14  Patients who sustained their concussion during a contact or collision sport- or recreation-related activity per the American Academy of Pediatrics classification15  were included in this study. Although not cited in the original classification, rugby was added as a contact or collision sport because of the frequent and intentional contact with other players or the ground, intensity of impact, and risk of injury. Exclusion criteria were a Glasgow Coma Scale score of ≤13, abnormal neuroimaging, neurosurgical intervention, multisystem injuries, developmental delay, intoxication, absence of trauma as the primary event, or previous enrollment in the study.

Study Protocol

Recruitment

Details of the 5P study design have been published,12  and are briefly summarized in the following paragraph. Eligible parents and patients provided written informed consent and assent as applicable before enrollment.

Standardized Assessment of Concussion

Trained research assistants collected participant data using a standardized assessment. Participants answered questions in electronic survey format in their first language (English or French) using a portable computer tablet. Parents and patients reported injury characteristics and risk factors for protracted recovery using the validated Acute Concussion Evaluation16  to assist in the initial evaluation of concussion. Additionally, parents and patients provided information on the type of sport played and use of protective equipment. Symptoms were measured using the Post-Concussion Symptom Inventory (PCSI).17  The PCSI is a self-reported measure of symptoms across the physical, cognitive, emotional, and sleep domains that has high internal consistency and interrater reliability.17,18  Age-appropriate symptom scales measure the difference between current and preinjury symptoms in children aged 5 to 7 years (13 items, 3-point scale), 8 to 12 years (17 items, 3-point scale), and 13 to 18 years (20 items, 7-point scale) and in a parent-reported version (20 items, 7-point scale). All data were collected and managed using Research Electronic Data Capture.19 

Follow-Up Questionnaires

Participants completed the age-appropriate PCSI at 1, 2, and 4 weeks after the initial ED visit via a web-based electronic survey or telephone interview. Research assistants telephoned nonresponders up to 5 times to minimize the loss to follow-up.

Outcome

The primary outcome was symptom score, operationalized as the item-averaged PCSI Δ score (difference between current and preinjury child-rated symptoms), with a possible score range from 0 to 6. To reconcile age-specific versions of the PCSI into a common metric, the following steps were undertaken: (1) when both the preinjury and postinjury scores were available for a constituent item, a Δ score was computed (postinjury score minus preinjury score) and then truncated to zero (if negative); (2) when a Δ score was available for at least 85% of constituent items, an average of all item Δ scores was computed; and finally, (3) this item-averaged Δ score for 5- to 7- and 8- to 12-year-old patients (original score range = 0–2) was multiplied by 3 to align with the original score range of 0 to 6 for adolescents (13–18-year-old patients).

Statistical Analysis

Baseline patient characteristics for each group were summarized using descriptive statistics. To estimate sex-specific relationships between mouthguard use and concussion symptoms at each of the 4 time points, we fitted a longitudinal, generalized least-squares multivariable model with the PCSI Δ score as the dependent variable and a 3-way interaction among mouthguard use, sex, and time (4 levels: initial assessment, 1 week, 2 weeks, and 4 weeks) as the main predictor of interest. We applied a continuous autoregressive (order 1) correlational structure to the model to account for within-participant measurements of the dependent variable and clustering by originating clinical site of study patient (9 levels). To minimize the potential for confounding bias, the model also featured comprehensive adjustment of covariates associated with clinical recovery. Covariates were chosen a priori based on recent systematic reviews,20,21  consensus and medical position statements,22,23  and clinical experience to adjust for preexisting factors and injury characteristics, including age, sex, symptom duration after previous concussion, family and personal history of migraine, history of anxiety, history of depression, history of sleep disorder, head contact if the injury involved a fall, fall height, helmet use, type of sport, number of school days missed in the past 6 months, learning disability, attention-deficit/hyperactivity disorder, duration of loss of consciousness, postinjury seizure, and location of head contact. Missing data were dealt with using listwise deletion. Wald χ2 statistics from initial model fitting were estimated to gain insights into the relative contribution of each independent variable to outcome prediction. To test our hypotheses, we performed a series of postmodel contrasts to formally quantify the adjusted comparisons of outcomes between mouthguard and non–mouthguard groups at each time point, stratified by sex (8 contrasts in total). These quantities represented the expected average difference in PCSI Δ score. Statistical analyses were performed using R (version 3.5.2; R Project for Statistical Computing).24  Two-sided P values were considered statistically significant at P < .05.

Participant Characteristics

Of 3063 children who participated in the 5P study, 1019 (median [interquartile range] age = 13.43 years [11.01–15.27 years]) were included in this substudy (male n = 746, 73.2%; Figure 1). Baseline participant characteristics for statistical modeling and mouthguard use are presented in Table 1. Overall, 424 participants (41.6%) reported wearing a mouthguard at the time of the concussion, with the highest proportions in rugby (58 of 64, 90.6%), football (86 of 119, 72.2%), and hockey (237 of 460, 51.5%; Table 2). Mouthguard use was more common among males (344 of 746, 46.1%) than females (80 of 273, 29.3%), notably in football and hockey, for which mouthguard use is mandated.

Figure 1

Participant flow diagram.

Figure 1

Participant flow diagram.

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Table 1

Baseline Characteristics of the 1019 Study Participants Who Sustained a Sport-Related Concussion Continued on Next Page

Baseline Characteristics of the 1019 Study Participants Who Sustained a Sport-Related Concussion Continued on Next Page
Baseline Characteristics of the 1019 Study Participants Who Sustained a Sport-Related Concussion Continued on Next Page
Table 2

MouthGuard Use Reported by Sport, Stratified by Sex

MouthGuard Use Reported by Sport, Stratified by Sex
MouthGuard Use Reported by Sport, Stratified by Sex

Effect of Mouthguard Use on Symptoms

Mouthguard use was not a strong contributor to concussion symptoms (⁠|$\({\rm{\chi }}_8^2\)$| = 9.08, P = .336). Sex (⁠|$\({\rm{\chi }}_8^2\)$| = 49.75, P < .001) and time after concussion (⁠|$\({\rm{\chi }}_8^2\)$| = 1825.54, P < .001) were independently and significantly associated with symptoms; however, postmodel fitting revealed no significant group-by-sex-by-time interaction for symptoms (⁠|$\({\rm{\chi }}_3^2\)$| = 0.27; P = .965), reflecting little indication that the association between mouthguard use and symptom score varied between sexes or across time (Figure 2). The contributions of all model predictors to symptoms are shown in the Supplemental Table (available online at http://dx.doi.org/10.4085/1062-6050-0393.20.S1). The estimated effect of wearing a mouthguard on symptoms at each time point, stratified by sex, is presented in Table 3.

Figure 2

Sex-stratified comparison of mouthguard effect on symptom score on the Post-Concussion Symptom Inventory (PCSI) at initial presentation in the emergency department and at weeks 1, 2, and 4. Predicted PCSI represents the median symptom scores for those wearing a mouthguard and those not wearing a mouthguard. The difference between curves represents the adjusted effect of wearing a mouthguard. a Indicates a difference between groups (P < .05).

Figure 2

Sex-stratified comparison of mouthguard effect on symptom score on the Post-Concussion Symptom Inventory (PCSI) at initial presentation in the emergency department and at weeks 1, 2, and 4. Predicted PCSI represents the median symptom scores for those wearing a mouthguard and those not wearing a mouthguard. The difference between curves represents the adjusted effect of wearing a mouthguard. a Indicates a difference between groups (P < .05).

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Table 3

Estimated Effect (Est) of Wearing a Mouthguard on Symptoms at Wk 0, 1, 2, and 4, Stratified by Sexa

Estimated Effect (Est) of Wearing a Mouthguard on Symptoms at Wk 0, 1, 2, and 4, Stratified by Sexa
Estimated Effect (Est) of Wearing a Mouthguard on Symptoms at Wk 0, 1, 2, and 4, Stratified by Sexa

Emergency Department

Males who wore a mouthguard reported similar symptom scores in the ED compared with males who did not wear a mouthguard (difference [diff] = −0.07; 95% CI = −0.23, 0.09, P = .389). Similarly, symptom scores were not different between females who wore a mouthguard and those who did not (diff = 0.22; 95% CI = −0.04, 0.48; P = .098).

Week 1

No difference was present in symptom scores between males who did and those who did not wear a mouthguard (diff = −0.02; 95% CI = −0.18, 0.14; P = .793). In contrast, female mouthguard wearers reported higher symptom scores at week 1 compared with non–mouthguard users (diff = 0.29; 95% CI = 0.01, 0.56, P = .039).

Week 2

By the second week, no differences in symptom scores were observed in males who wore a mouthguard compared with those who did not (diff = −0.03; 95% CI = −0.19, 0.13, P = .719). Females who wore mouthguards described similar symptom scores as those who did not (diff = 0.22; 95% CI = −0.06, 0.51; P = .128).

Week 4

No difference was demonstrated in symptom scores between males who did and those who did not wear a mouthguard at 4 weeks (diff = −0.13; 95% CI = −0.29, 0.04, P = .127). Wearing a mouthguard had no effect on symptom scores among females compared with not wearing one (diff = 0.08; 95% CI = −0.20, 0.36; P = .581).

Regardless of sex, wearing a mouthguard at the time of concussion was not associated with reduced symptoms at baseline or 1, 2, or 4 weeks postinjury in children and adolescents compared with those who did not wear a mouthguard. Although a statistically observable difference was present in symptom severity between females who did and those who did not wear a mouthguard at 1 week after concussion, the estimated difference was small and deemed clinically nonrelevant. Our results did not support our hypothesis that mouthguards would be associated with reduced concussion symptoms, but they confirmed our hypothesis of no sex-specific differences.

More males wore mouthguards in sports for which their use was mandatory or recommended, yet the symptom scores were similar between sexes. Previous authors25,26  have shown that high school females had a higher incidence of concussion and prolonged symptom recovery in sex-comparable sports; however, we are the first to examine whether differences in symptom recovery existed between sexes associated with mouthguard use. Whereas the finding that females reported worse symptoms at baseline may help explain differences in prolonged recovery,25,26  our results suggested that wearing a mouthguard did not change the recovery pattern between sexes. High-quality, adequately powered studies are needed to examine sport-specific sex differences in mouthguard use and outcomes.

Our findings are consistent with those of a small number of authors10,11  who identified no differences in the concussion burden associated with mouthguard use in an adolescent population. Limited evidence11  indicated that mouthguard use was not associated with neurocognitive deficits or the degree of symptoms in adolescents within 3 days of concussion. Similarly, no differences in missed playing time due to concussion were found between high school football athletes who wore custom versus generic or specialized mouthguards.10  Although our results support the finding that mouthguards did not play a role in symptom severity after SRC in youth, they stand in contrast to preliminary outcomes in an elite professional athlete population. Professional male ice hockey players who did not wear mouthguards reported greater symptom severity as measured by the modified McGill Acute Concussion Evaluation symptom scale than those who did wear mouthguards.9  Possible explanations for the different findings include physiological differences between children and adults, higher impact forces in professional ice hockey, and differences in symptom scales. Because the protective effects of mouthguards might be more pronounced in collision sports compared with low-contact sports, sport-specific studies are needed to confirm our results.

Examining the effectiveness of mouthguards in preventing concussions lends support to the lack of a protective effect of mouthguards on concussion severity. Our findings are strengthened by recent systematic reviews and meta-analyses6,7  that demonstrated an inconclusive association between mouthguard use and concussion incidence. It is also unclear whether wearing a custom mouthguard relative to a noncustom mouthguard confers any increased protection against concussion, although custom mouthguards have been associated with a predominantly negative effect, ranging from a 1% reduced to a 75% increased risk of concussion among university football players over a 15-week season.27 

Overwhelming evidence supports the use of mouthguards to prevent dental injuries such as jaw fractures, dental trauma, and soft tissue injuries.5  Authors of biomechanical studies5,28  have suggested that mouthguards may reduce the incidence and severity of concussions by increasing the space within the temporomandibular joint and absorbing impact forces directed from the mandible to the base of the skull, thereby reducing the forces transmitted to the brain. It seems intuitive that mouthguards might offer protection from a direct blow to the maxilla or by buffering a forced occlusion during traumatic jaw closure. However, it is less convincing that mouthguards might offer protection against high levels of neuronal strain caused by rotational acceleration forces applied to the brain if an athlete is struck perpendicularly on the mandible with an open mouth or sustains an indirect blow.

Clinical Relevance

Our results should not discourage athletes from wearing mouthguards during sport but rather should provide youths with a reasonable expectation as to their purpose and discourage the unjustified promotion or purchase of mouthguards to protect against concussion symptoms. Using mouthguards might give athletes a false sense of protection and encourage them to play more aggressively,29  putting themselves at an increased risk for injury. Rather, efforts to reduce the number and severity of concussions through validated means such as eliminating body checking in youth ice hockey, rule changes, education, and fair play should be encouraged.6 

This research had several strengths. First, existing population-based studies were often sport specific and focused on acute symptoms in adult males or elite athletes. We prospectively measured symptom scores in all youth with a sport- or recreation-related concussion who were seen within hours of injury at multiple pediatric hospitals across Canada and examined symptom recovery in the first month. Second, we supplied a novel contribution to the literature by providing a sex-based comparison. Third, we used validated and developmentally relevant symptom scales that were scaled appropriately to compare symptoms across a wide range of ages. We considered this important given the limited evidence of mouthguard use in younger children. By including children of all ages who participated in multiple sports, we ensured that our results can be generalized to a diverse range of recreational and competitive athletes across a variety of sports and not limited to contact sports such as football or hockey. Fourth, we controlled for multiple confounders associated with clinical recovery to strengthen the validity of our findings.

Our results are novel because we demonstrated that outcomes associated with mouthguards were not sex specific, even when controlling for symptom duration with previous concussion, medical history, and injury characteristics. Moreover, this study is unique in that we prospectively measured symptom change during the initial 4 weeks at 9 pediatric EDs across Canada using validated and developmentally appropriate symptom scales. By including youth who participated in more than 20 organized sports, we ensured that our results can be generalized to both recreational and competitive athletes across multiple sports and not limited to contact sports such as football or hockey. Additionally, our multivariable model included established risk factors for concussion recovery.

Limitations

Developmental differences across our participants regarding musculoskeletal strength may have influenced our results. Although neck strength is similar between sexes in younger children, sex differences exist among adolescents.30  Sex differences in neck strength have been proposed as one possible explanation for the higher risk of concussion among females in sex-comparable sports.21  There is growing interest in examining the association between neck strength and SRC given that an SRC may be caused by either a direct or indirect blow to the head or neck or elsewhere on the body.22  The neck has a potential role in reducing the risk of concussion by stabilizing the head against large acceleration forces and absorbing the transfer of energy from the head to the brain.31  Preliminary evidence32  for the importance of neck strength in high school athletes suggests that greater isometric neck strength reduced the risk of concussion. Given that this study is a secondary analysis of a larger prospective, multicenter cohort investigation to derive and validate a clinical prediction rule for persistent postconcussive symptoms in children and adolescents that did not include measures of musculoskeletal strength,13  we were unable to control for differences in neck strength in our analysis. We did, however, control for sex and sport type, both of which have been found to independently predict the risk of concussion in a univariate analysis.32  We were unable to control directly for musculoskeletal strength, but we controlled for age, which may share similarities with developmental changes in neck strength as a covariate.

Several other possible limitations may have affected our study. Although it has been hypothesized that the improved fit, thickness, stiffness, tensile strength, and durability of custom-made mouthguards provide superior shock absorption and protection versus more commonly used boil-and-bite mouthguards,11  this was a secondary analysis of a large data set that did not include detailed descriptions of mouthguard types worn at the time of injury, thereby precluding our ability to include this factor in the analysis. Children under the age of 13 may be more likely to wear less expensive, noncustom mouthguards because of the need to replace the device more frequently with changes in dentition and jaw sizes. It is possible that discriminating among mouthguard types would have produced different results, although the lack of difference in days lost among high school football players wearing custom versus generic mouthguards suggested otherwise.10  To determine the effect of mouthguards as compared with the association of outcomes with their use would require a randomized controlled trial, yet ethical considerations constrain randomizing participants to a non–mouthguard group given the strong evidence for the dental protection of wearing a mouthguard. However, the large prospective cohort in this study helps to minimizes this limitation in that the sample size was adequately powered to control for known confounders. Additionally, 30% to 40% of concussions sustained by adolescent athletes are not reported,33  and only 12% of patients aged 0 to 17 years have been shown to access the ED for concussion care.34  Even though concussion patients seeking care in the ED may present with more severe injuries than those who do not report their injuries, higher rates of persistent symptoms have been shown in patients assessed in sport medicine and specialty clinics.35,36  Further research is required to assess the effect of mouthguard use in patients recruited from different medical settings and sport types. Also, we truncated symptom differences to zero under the assumption that negative scores would most likely indicate a patient response error for a preinjury item, as a return to baseline level is far more realistic. Although this may have introduced some error, it is unlikely to have affected the overall results. Finally, because no objective biomarkers exist for concussion diagnosis or recovery, our study was limited to patient self-reports to measure symptom persistence.

Wearing a mouthguard at the time of concussion did not reduce symptoms in the first month after SRC among either males or females who were treated in the ED compared with not wearing a mouthguard. Nonetheless, we endorse international dental association and consensus statement recommendations to wear a mouthguard in sport,37,38  as overwhelming evidence exists to support the use of mouthguards in preventing dental injuries.

We thank the parents and children who enrolled in this study and acknowledge the research coordinators and research assistants responsible for patient recruitment, enrollment, and follow-up across the 8 sites. Student volunteers assisted with patient screening in the following EDs: Children's Hospital of Eastern Ontario, Alberta Children's Hospital, Hospital for Sick Children, and Centre Hospitalier Universitaire Sainte-Justine. We appreciate the collaboration and assistance of all the treating physicians working in the emergency departments across the sites. We are grateful to Pediatric Emergency Research Canada for making this study possible.

1. 
Bryan
MA,
Rowhani-Rahbar
A,
Comstock
RD,
Rivara
F;
Seattle Sports Concussion Research Collaborative. Sports- and recreation-related concussions in US youth
.
Pediatrics
.
2016
;
138
(1)
:
e20154635
.
2. 
Sarmiento
K,
Thomas
KE,
Daugherty
J,
et al
Emergency department visits for sports- and recreation-related traumatic brain injuries among children—United States, 2010–2016
.
MMWR Morb Mortal Wkly Rep
.
2019
;
68
(10)
:
237
242
.
3. 
Broglio
SP,
Cantu
RC,
Gioia
GA,
et al
National Athletic Trainers' Association. National Athletic Trainers' Association position statement: management of sport concussion
.
J Athl Train
.
2014
;
49
(2)
:
245
265
.
4. 
Marshall
SW,
Loomis
DP,
Waller
AE,
et al
Evaluation of protective equipment for prevention of injuries in rugby union
.
Int J Epidemiol
.
2005
;
34
(1)
:
113
118
.
5. 
Knapik
J,
Marshall
S,
Lee
R,
et al
Mouthguards in sport activities: history, physical properties and injury prevention effectiveness
.
Sports Med
.
2007
;
37
(2)
:
117
144
.
6. 
Emery
CA,
Black
AM,
Kolstad
A,
et al
What strategies can be used to effectively reduce the risk of concussion in sport? a systematic review
.
Br J Sports Med
.
2017
;
51
(12)
:
978
984
.
7. 
Knapik
JJ,
Hoedebecke
BL,
Rogers
GG,
Sharp
MA,
Marshall
SW.
Effectiveness of mouthguards for the prevention of orofacial injuries and concussions in sports: systematic review and meta-analysis
.
Sports Med
.
2019
;
49
(8)
:
1217
1232
.
8. 
Chisholm
DA,
Black
AM,
Palacios-Derflingher
L,
et al
Mouthguard use in youth ice hockey and the risk of concussion: nested case-control study of 315 cases
.
Br J Sports Med
.
2020
;
54
(14)
:
866
870
.
9. 
Benson
B,
Meeuwisse
W.
The risk of concussion associated with mouthguard use among professional hockey players
.
Clin J Sport Med
.
2005
;
15
(5)
:
392
397
.
10. 
McGuine
TA,
Hetzel
S,
McCrea
M,
Brooks
MA.
Protective equipment and player characteristics associated with the incidence of sport-related concussion in high school football players: a multifactorial prospective study
.
Am J Sports Med
.
2014
;
42
(10)
:
2470
2478
.
11. 
Mihalik
JP,
McCaffrey
MA,
Rivera
EM,
et al
Effectiveness of mouthguards in reducing neurocognitive deficits following sports-related cerebral concussion
.
J Athl Train
.
2007
;
23
(1)
:
14
20
.
12. 
Zemek
R,
Osmond
M,
Barrowman
N;
Pediatric Emergency Research Canada (PERC) Concussion Team. Predicting and preventing postconcussive problems in paediatrics (5P) study: protocol for a prospective multicentre clinical prediction rule derivation study in children with concussion
.
BMJ Open
.
2013
;
3
(8)
:
e003550
.
13. 
Zemek
R,
Barrowman
N,
Freedman
SB,
et al
Pediatric Emergency Research Canada (PERC) Concussion Team. Clinical risk score for persistent postconcussion symptoms among children with acute concussion in the ED
.
JAMA
.
2016
;
315
(10)
:
1014
1025
.
14. 
McCrory
P,
Meeuwisse
WH,
Aubry
M,
et al
Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012
.
Br J Sports Med
.
2013
;
47
(5)
:
250
258
.
15. 
Committee on Sports Medicine.
Recommendations for participation in competitive sports
.
Pediatrics
.
1988
;
81
(5)
:
737
739
.
16. 
Gioia
GA,
Collins
M,
Isquith
PK.
Improving identification and diagnosis of mild traumatic brain injury with evidence: psychometric support for the Acute Concussion Evaluation
.
J Head Trauma Rehabil
.
2008
;
23
(4)
:
230
242
.
17. 
Gioia
GA,
Isquith
PK,
Schneider
JC,
Vaughan
CG.
New approaches to assessment and monitoring of concussion in children
.
Top Lang Disord
.
2009
;
29
(3)
:
266
281
.
18. 
Sady
MD,
Vaughan
CG,
Gioia
GA.
Psychometric characteristics of the postconcussion symptom inventory in children and adolescents
.
Arch Clin Neuropsychol
.
2014
;
29
(4)
:
348
363
.
19. 
Harris
PA,
Taylor
R,
Thielke
R,
Payne
J,
Gonzalez
N,
Conde
JG.
Research Electronic Data Capture (REDCap)—a metadata-driven methodology and workflow process for providing translational research informatics support
.
J Biomed Inform
.
2009
;
42
(2)
:
377
381
.
20. 
Davis
GA,
Anderson
V,
Babl
FE,
et al
What is the difference in concussion management in children as compared with adults? A systematic review
.
Br J Sports Med
.
2017
;
51
(12)
:
949
957
.
21. 
Iverson
GL,
Gardner
AJ,
Terry
DP,
et al
Predictors of clinical recovery from concussion: a systematic review
.
Br J Sports Med
.
2017
;
51
(12)
:
941
948
.
22. 
McCrory
P,
Meeuwisse
W,
Dvorak
J,
et al
Consensus statement on concussion in sport—the 5th International Conference on Concussion in Sport held in Berlin, October 2016
.
Br J Sports Med
.
2017
;
51
(11)
:
838
847
.
23. 
Harmon
KG,
Clugston
JR,
Dec
K,
et al
American Medical Society for Sports Medicine position statement on concussion in sport
.
Clin J Sport Med
.
2019
;
29
(2)
:
87
100
.
24. 
The R project for statistical computing
.
The R Foundation Web site
.
Accessed July 1,
2021
.
25. 
Bretzin
AC,
Covassin
T,
Fox
ME,
et al
Sex differences in the clinical incidence of concussions, missed school days, and time loss in high school student-athletes: part I
.
Am J Sports Med
.
2018
;
46
(9)
:
2263
2269
.
26. 
Ono
KE,
Burns
TG,
Bearden
DJ,
McManus
SM,
King
H,
Reisner
A.
Sex-based differences as a predictor of recovery trajectories in young athletes after a sports-related concussion
.
Am J Sports Med
.
2016
;
44
(3)
:
748
752
.
27. 
Wisniewski
JF,
Guskiewicz
K,
Trope
M,
Sigurdsson
A.
Incidence of cerebral concussions associated with type of mouthguard used in college football
.
Dent Traumatol
.
2004
;
20
(3)
:
143
149
.
28. 
Winters
J,
DeMont
R.
Role of mouthguards in reducing mild traumatic brain injury/concussion incidence in high school football athletes
.
Gen Dent
.
2014
;
62
(3)
:
34
38
.
29. 
Hagel
B,
Meeuwisse
W.
Risk compensation: a “side effect” of sport injury prevention?
Clin J Sport Med
.
2004
;
14
(4)
:
193
196
.
30. 
Lavallee
AV,
Ching
RP,
Nuckley
DJ.
Developmental biomechanics of neck musculature
.
J Biomech
.
2013
;
46
(3)
:
527
534
.
31. 
Streifer
M,
Brown
AM,
Porfido
T,
Anderson
EZ,
Buckman
JF,
Esopenko
C.
The potential role of the cervical spine in sports-related concussion: clinical perspectives and considerations for risk reduction
.
J Orthop Sports Phys Ther
.
2019
;
49
(3)
:
202
208
.
32. 
Collins
CL,
Fletcher
EN,
Fields
SK,
et al
Neck strength: a protective factor reducing risk for concussion in high school sports
.
J Prim Prev
.
2014
;
35
(5)
:
309
319
.
33. 
Register-Mihalik
J,
Guskiewicz
K,
McLeod
T,
Linnan
L,
Mueller
F,
Knowledge
Marshall S.,
attitude, and concussion-reporting behaviors among high school athletes: a preliminary study
.
J Athl Train
.
2013
;
48
(5)
:
645
653
.
34. 
Arbogast
KB,
Curry
AE,
Pfeiffer
MR,
et al
Point of health care entry for youth with concussion within a large pediatric care network
.
JAMA Pediatr
.
2016
;
170
(7)
:
e160294
.
35. 
Casson
IR,
Sethi
NK,
Meehan
WP
III.
Early symptom burden predicts recovery after sport-related concussion
.
Neurology
.
2015
;
85
(1)
:
110
111
.
36. 
Rosenbaum
PE,
Locandro
C,
Chrisman
SPD,
et al
Characteristics of pediatric mild traumatic brain injury and recovery in a concussion clinic population
.
JAMA Netw Open
.
2020
;
3
(11)
:
e2021463
.
37. 
Canadian Dental Hygienists Association.
CDHA position paper on sports mouthguards putting more bite into injury prevention
.
Can J Dent Hyg
.
2005
;
39
(6)
:
257
281
.
38. 
Lloyd
JD,
Nakamura
WS,
Maeda
Y,
et al
Mouthguards and their use in sports: report of the 1st International Sports Dentistry Workshop, 2016
.
Dent Traumatol
.
2017
;
33
(6)
:
421
426
.