Speech Performance of Rugby Players When Using Different Types of Mouthguard
Phase: NA
Conditions: Speech
Sponsor: Amy Liew

 
 
 
 
 
Speech Performance of Rugby 
Players when Using Different 
Types of Mouthguard 
Research Protocol 
May 18, 2018 

 
 
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Table of content 
 
1. Introduction 
2. Problem Statement 
3. Research Questions 
4. Hypothesis 
5. Aim and Objectives 
6. Methodology 
7. References 
8. Flow Chart of Methodology 
 
 
 
 
 
 
 
 
 
 
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1. Introduction 
Participation in sports carries a considerable risk for dental injuries (Sane, 1998). The 
prevalence and severity of sport related dental injuries varied, with an estimate between 0.2% 
and 33.5%, but is likely to be underreported (Cohenca et al., 2007). The risk of injuries in-
creased with the age of the players, especially among those involved in long hours of training 
and compete professionally (Turbeville et al., 2003). Dental trauma often involves injuries to 
the tooth structure, periodontal tissue, oral mucosa and temporomandibular joints (Feliciano, 
2006). The vulnerable site is upper jaw, particularly upper incisors (Glendor, 2008). These 
injuries often affect the appearance of the casualties, causing undue psychological stress (Ber-
ger, 2009). Furthermore restoring the injured teeth often requires extensive dental procedure 
with long-term follow-up at a high cost (Glendor, 2001). Thus, preventing the occurrence of 
dental trauma is crucial. 
Mouthguards are typically composed of a thermoplastic copolymer, designed to fit over 
the occlusal surfaces of the maxillary teeth and extending near to the vestibular reflection (Pat-
rick et al., 2005). Several authors demonstrated that wearing a mouthguard during sport can 
reduce the occurrence and severity of dental trauma (Yesil et al., 2009). Therefore, some sports 
authorities mandate the use of mouthguard (Quarrie et al., 2005).The purpose of using a 
mouthguard is to act as a buffer from trauma and provide a degree of protection for both the 
mouth’s soft tissues (lips, gums, tongue) and hard tissues (teeth and alveolar bone) as well as 
protection from brain injuries (Knapik et al.,2007). The ability to protect the mouth is highly 
dependent on the ability of the mouthguard in shock absorption and impact dissipation (Craig 
et al., 2002). 
There are basically three types of mouthguards that are available in the market. Type I 
(stock) are sold to the public and are used without any modification. Type II (‘boil and bite’) 

 
 
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mouthguards are the most commonly used mouthguards on the market and represent 90% of 
all mouthguards worn (Padilla et al., 1996). These are made of a thermoplastic material that is 
softened and then moulded to the dental arch by the user. Type III (custom-made) are made by 
a dentist using a mould of the patient’s dental arches (Barbic et al., 2005). 
However, the compliance of mouthguard use is often low. Among Malaysian university 
rugby players, those who discontinued using mouthguard complaint that general discomfort 
and speech disturbance are the main barriers to the compliance (Liew et al., 2014). The nui-
sance may be due to their use of poorly-fitted stock or boil-and-bite mouthguards (Liew et al., 
2014). In comparison, custom-fitted mouthguards were considered the best choice because of 
its ability to maintaining oral moistness and adaptation, hence causing less interference with 
respiration and speech, while improving comfort and limiting nauseating effect (Duarte-Pereira 
et al., 2008). However, limited availability and higher prices hinder its widespread use (Gue-
vara et al., 2001).  
To date, the intensity and duration of oral discomfort caused by mouthguard remains 
unclear, with no published study to evaluate speech performance that employed acoustic anal-
ysis and sonography. Hence, the aim of this research is to evaluate the impact of wearing 
mouthguards on the speech performance of the athletes. 
 
 
 

 
 
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2. Problem Statement 
Participation in sports expose players to increased risk of dental trauma. Thus, the pur-
pose of wearing a mouthguard is to act as a buffer from trauma and provide a degree of pro-
tection for both the mouth’s soft tissues (lips, gums, tongue) and hard tissues (teeth and alveolar 
bone). However, general discomfort and speech disturbance are the main barriers to the com-
pliance of mouthguard use. The nuisance may be due to the use of poorly-fitted boil-and-bite 
mouthguards. In comparison, custom-fitted mouthguards were often considered the best choice 
because of its ability to maintaining oral moistness and adaptation, hence causing less interfer-
ence with respiration and speech, while improving comfort and limiting nauseating effect. Nev-
ertheless, the intensity and duration of oral discomfort caused by mouthguard remains unclear, 
with no published study to compare speech performance when using different types of 
mouthguard. 
Therefore, this project is intended to compare the impact of different types of 
mouthguard on the speech performance of the athletes.   
 
3. Research Questions 
Is there any difference in speech performance when using ‘boil and bite’ and custom-fitted 
mouthguards? 
 
4. Hypothesis 
There is no difference in speech performance when using ‘boil and bite’ and custom-fitted 
mouthguards. 
 
 

 
 
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5. Aim and Objectives 
Aim: 
To compare the speech performance when using ‘boil and bite’ and custom-fitted mouthguards. 
Objectives: 
a) To provide ‘boil and bite’ and custom-fitted mouthguards to athletes. 
b) To compare the immediate speech performance when using ‘boil and bite’ and custom-
fitted mouthguards based on the auditive analysis and sonography of the mouthguard users. 
 
 

 
 
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6. Methodology 
Selection criteria 
The inclusion criteria are as follows: 
(i) adult female aged 18 years old and older;  
(ii) currently representing the nation and participating actively in rugby; and  
(iii) native speakers of Malay (national language).  
The exclusion criteria are as follows: 
(i) did not play rugby within the last six months;  
(ii) edentulism;  
(iii) has used a mouthguard, orthodontic appliance or removable prosthodontics appliance 
within the last six months;  
(iv) known history of allergy to polymers; and  
(v) medical problems (ASA classification 3 and above). 
 
 

 
 
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Sample size  
The sample size required is determined using G*Power software (available at: 
http://www.gpower.hhu.de/). The assumptions were an effect size of 0.25, 5% margin error, 
80% power, within-subject measurements for the two types of mouthguard and control – not 
wearing any mouthguard. Correlation among measures was set at 0.5. This yielded a minimal 
sample size of 28. A drop-out rate of 10% was expected between first visit and fitting visit. Thus, the 
total sample size was adjusted to 32.  
Interventions 
Informed consent will be obtained before the commencement of the study. Interested 
participants must provide consent in written form. Simple questions will be asked to inquire 
about demographic details and the use of mouthguards and problems faced if not wearing one 
at the moment. Also, questions will be asked regarding existing speech impairment or disturb-
ance. 
Dental examination will be carried out to all the consented participants to identify eden-
tulism and prosthesis in the mouth. Dental impression will be taken using alginate impression 
material and rigid perforated stainless steel trays. The impressions will be rinsed under running 
tap water before spraying with disinfectant. The impressions will be transported in sealed and 
labelled zip-lock bags. 
The impressions will be casted within the same day using Type II dental stone. Fabri-
cation of mouthguards will be carried out by technicians using Essix mouthguard sheets and 
vacuum machine, with the edges extend towards the vestibule and even thickness of 4mm. 
Sharp edges will be smoothened. 
At the fitting session, each participant will be given a ‘boil and bite’ mouthguard and a 
custom-fitted mouthguard. For ‘boil and bite’ mouthguards, the participants will immerse the 

 
 
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acrylic sheet in a bowl of hot water and fit the softened sheet on their dental arches, following 
the manufacturer’s instructions. The completed custom mouthguards will be fitted. Any com-
plaint of sharp edges will be handled. The players will then be instructed on the care of the 
mouthguards.  
Immediately after fitting, speech performance will be recorded digitally in standardized 
conditions in a soundproof room. The volunteers will be asked to pronounce 5 two-syllable 
words with different consonant: paku, bola, dadu, tatu. Four recordings will be done, for each 
of the following conditions: (i) not using mouthguard; (ii) using a ‘boil and bite’ mouthguard; 
and (iii) using a custom-fitted mouthguard. The recording samples will be digitized into a com-
puter. 
 
Data analysis 
Demographic data will be summarized using descriptive statistics. Audio recordings 
will be digitized with Praat software. Mean voice onset time will be compared using repeated 
measure ANOVA with post hoc Tukey test. However, if normality assumption is violated, the 
non-parametric equivalent, Friedman’s test and post hoc Wilcoxon signed-rank test will be 
used. 
 
 

 
 
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7. References: 
1. Berger TD, Kenny DJ, Casas MJ, Barrett EJ, Lawrence HP. Effects of severe dentoalveolar 
trauma on the quality-of-life of children and parents. Dent Traumatol 2009;25:462–9.  
2. Caniklioglu C, Ozturk Y. Patient discomfort: a comparison between lingual and labial fixed 
appliances. Angle Orthod. 2005;75:86–91.  
3. Cohenca N, Roges R, Rogers R. The incidence and severity of dental trauma in intercolle-
giate athletes. JADA Vol. 138: August 2007 P 11211126 
4. Craig RG, Godwin WC. Properties of athletic mouth protectors and materials. J Oral Rehab 
2002;29:146–50.  
5. Duarte-Pereira DMV, Del Rey-Santamaria M, Javierre-Garc es C, Barbany-Cair o J, 
Paredes-Garcia J, Valmaseda-Castellon E et al. Wearability and physiological effects of 
custom-fitted vs. self-adapted mouthguards. Dent Traumatol 2008;24:439–42. 
6. Feliciano KMPC, De Franca Caldas A Jr. A systematic review of the diagnostic classifica-
tions of traumatic dental injuries. Dent Traumatol 2006;22:71–6.  
7. Glendor U, Jonsson D, Halling A, Lindqvist K. Direct and indirect costs of dental trauma 
in Sweden: a 2-year prospective study of children and adolescents. Community Dent Oral 
Epidemiol 2001;29:150–60. 
8. Glendor U. Epidemiology of traumatic dental injuries–a 12 year review of the literature. 
Dent Traumatol 2008;24:603–11. 
9. Goldon Williams. Player communication in rugby. NWAA Development Coach 2005. 
10. Guevara, P. H., Hondrum, S. O., & Reichl, R. B. (2001). A comparison of commercially 
available mouthguards and a custom mouthguard. General dentistry, 49(4), 402–406. 

 
 
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11. Knapik J, Marshall S, Lee R, Darakjy S, Jones S, Mitchener T, et al. Mouthguards in sport 
activities: history, physical properties and injury prevention effectiveness. Sports Med 
2007;37:117-44.  
12. Liew AKC, Abdullah D, Wan Noorina WA, Khoo S. Factors associated with mouthguard 
use and discontinuation among rugby players in Malaysia. Dent Traumatol 
2014;30(6):461-467. 
13. Padilla R, Dorney B, Balikov S. Prevention of oral injuries. J Calif Dent Assoc 
1996;24(3):30-6. 
14. Patrick DG, van Noort R, Found MS.Scale of protection and the various types of sports 
mouthguard: Br J Sports Med. 2005 May;39(5):278-81. 
15. Quarrie KL, Gianotti SM, Chalmers DJ, Hopkins WG. An evaluation of mouthguard re-
quirements and dental injuries in New Zealand rugby union. Br J Sports Med 2005;39:650–
1. 
16. Rosendal L, Langberg H, Skov-Jensen A, Kjaer M.Incidence of injury and physical perfor-
mance adaptations during military training. Clin J Sport Med. 2003 May;13(3):157-63. 
17. Sane J, Ylipaavalnimei P. Dental trauma in contact team sports. Endodontic and Dent Trau-
matol 1988;4:164-169. 
18. Turbeville SD, Cowan LD, Owen WL, Asal NR, Anderson MA. Risk factors for injury in 
high school football players. Am J Sports Med 2003;31:974–80.  
19. Yesil Duymus Z, Gungor H. Use of mouthguard rates among university athletes during 
sport activities in Erzurum,Turkey. Dent Traumatol 2009;25:318–22.  

 
 
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8. Flowchart of Methodology 
 
Research proposal submission to UKM Research Ethics Committee for permis-
sion on conducting study. 
Information sheet, consent form and simple questions will be asked to inquire 
about demographic details and the use of mouthguards. 
Impression taking using alginate impression material and rigid perforated 
stainless steel trays. 
Mouthguard fitting  
Speech performance recording 
Selection of athletes fulfilling the selection criteria. 
Letter to various sports associations and athletes for permission of conducting 
research. 
Data analysis