Rugby Union - Six Nations Championship - Ireland v Scotland - Aviva Stadium, Dublin, Ireland - February 1, 2020 Ireland's Tadhg Furlong with gumshield tucked into socks REUTERS/Russell Cheyne

Rugby League - Super League - Huddersfield Giants vs Castleford Tigers - John Smith's Stadium, Huddersfield, Britain - April 8, 2018 General view of Castlefords' Joe Wardle's gumshield Action Images/Lee Smith

Boxing - Lee Selby vs Jonathan Barros - IBF World Featherweight Title - London, Britain - July 15, 2017 Lee Selby in action with Jonathan Barros as a gumshield comes out Action Images via Reuters/Paul Childs

Football Soccer Britain - Watford v Everton - Premier League - Vicarage Road - 10/12/16 Watford's Heurelho Gomes with a mouthguard with the Brazilian flag on it Action Images via Reuters / Alan Walter Livepic EDITORIAL USE ONLY. No use with unauthorized audio, video, data, fixture lists, club/league logos or "live" services. Online in-match use limited to 45 images, no video emulation. No use in betting, games or single club/league/player publications. Please contact your account representative for further details.

Football Soccer Britain - Watford v Everton - Premier League - Vicarage Road - 10/12/16 Watford's Heurelho Gomes with a mouthguard with the Brazilian flag on it Action Images via Reuters / Alan Walter Livepic EDITORIAL USE ONLY. No use with unauthorized audio, video, data, fixture lists, club/league logos or "live" services. Online in-match use limited to 45 images, no video emulation. No use in betting, games or single club/league/player publications. Please contact your account representative for further details.

Canada's Milos Raonic bites his mouthguard during his quarter-final match against France's Gael Monfils at the Australian Open tennis tournament at Melbourne Park, Australia, January 27, 2016. REUTERS/Tyrone Siu

Canada's Milos Raonic bites his mouthguard during his fourth round match against Switzerland's Stan Wawrinka at the Australian Open tennis tournament at Melbourne Park, Australia, January 25, 2016. REUTERS/Thomas Peter

Canada's Milos Raonic wears a mouthguard during his first round match against France's Lucas Pouille at the Australian Open tennis tournament at Melbourne Park, Australia, January 19, 2016. REUTERS/Brandon Malone

Canada's Milos Raonic wears a mouthguard during his first round match against France's Lucas Pouille at the Australian Open tennis tournament at Melbourne Park, Australia, January 19, 2016. REUTERS/Brandon Malone

Apr 26, 2014; Baltimore, MD, USA; Jon Jones hits Glover Teixeira with an upper cut during the UFC light heavy weight championship fight at Baltimore Arena. Jones retained the light heavy weight championship by defeating Teixeria. Mandatory Credit: Tommy Gilligan-USA TODAY Sports

Britain's Katie Summerhayes reacts at the finish line during the women's freestyle skiing slopestyle qualification event at the Sochi 2014 Winter Olympics in Rosa Khutor February 11, 2014. REUTERS/Mike Blake (RUSSIA - Tags: SPORT SKIING OLYMPICS TPX IMAGES OF THE DAY)

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Juan De Leon, coach of Polish challenger Mariusz Wach (C), removes the gumshield after the fight against Ukrainian WBA, WBO, IBO and IBF heavy weight boxing world champion Vladimir Klitschko in Hamburg November 10, 2012. World heavyweight champion Klitschko was made to go the distance against Wach but earned a unanimous points decision on Saturday to retain his four title belts. REUTERS/Morris Mac Matzen (GERMANY - Tags: SPORT BOXING)

Ukraine's Vyacheslav Glazkov (R) punches Germany's Konstantin Airich during their WBC Baltic Silver heavyweight title fight in Moscow September 8, 2012. Glazkov won the match. Picture taken September 8, 2012. REUTERS/Maxim Shemetov (RUSSIA - Tags: SPORT BOXING PROFILE TPX IMAGES OF THE DAY)

Scotland's Al Kellock (L) loses his gumshield as he attempts to tackle England's Ben Foden during their Six Nations rugby union match at Murrayfield Stadium in Edinburgh March 13, 2010. REUTERS/Russell Cheyne (BRITAIN - Tags: SPORT RUGBY)

Scotland's Al Kellock (L) loses his gumshield as he attempts to tackle England's Ben Foden during their Six Nations rugby union match at Murrayfield Stadium in Edinburgh March 13, 2010. REUTERS/Russell Cheyne (BRITAIN - Tags: SPORT RUGBY)

Los Angeles Lakers guard Kobe Bryant (L) and Dallas Mavericks forward Dirk Nowitzki embrace before the start of their NBA basketball game in Dallas, Texas January 13, 2010. REUTERS/Mike Stone (UNITED STATES - Tags: SPORT BASKETBALL)

U.S. based Ola Afolabi celebrates after knocking out Britain's Enzo Maccarinelli in their Interim World Cruiserweight championship fight Manchester, northern England, March 14, 2009. REUTERS/Phil Noble (BRITAIN SPORT BOXING IMAGE OF THE DAY TOP PICTURE)

Lebron James of the U.S. shows his USA mouthpiece during the gold medal basketball game against Spain at the Beijing 2008 Olympic Games, August X24 2008. REUTERS/Sergio Perez (CHINA)

Luis Porozo of Ecuador (L) fights Roberto Navarro of the Dominican Republic during their men's featherweight (57kg) round of 32 boxing match at the Beijing 2008 Olympic Games August 11, 2008. REUTERS/Lee Jae-Won (CHINA)

Chris Bosh of the U.S. reacts during their friendly basketball game against Russia as part of their training for the Beijing Olympics in Shanghai August 3, 2008. REUTERS/Aly Song (CHINA)

Zab Judah of the U.S. clinches with Joshua Clottey of Ghana during their IBF welterweight title fight at the Palms Casino Resort in Las Vegas, Nevada August 2, 2008. Clottey won the vacant title by unanimous decision after the fight was stopped in the ninth round. REUTERS/Steve Marcus (UNITED STATES)

Chris Bosh of the U.S. gestures during their friendly basketball game against Turkey as part of their training for the Beijing Olympics, at the Venetian Macao-Resort-Hotel in Macau July 31, 2008. REUTERS/Victor Fraile (CHINA) (BEIJING OLYMPICS 2008 PREVIEW)

Cleveland Cavaliers' LeBron James reacts during a break in play in the second half of Game 5 of their NBA Eastern Conference semi-final basketball playoff series against the Boston Celtics in Boston, Massachusetts May 14, 2008. REUTERS/Adam Hunger (UNITED STATES)

Cleveland Cavaliers forward LeBron James reacts after hearing the results of an official review that awarded the Cavaliers two foul shots against the Philadelphia 76ers in fourth quarter NBA basketball action in Philadelphia, Pennsylvania, April 14, 2008. REUTERS/Tim Shaffer (UNITED STATES)

A boxer rests during a training session at the Excelsior Boxe Gym in Marcianise, near Naples, southern Italy, January 4, 2008. Three of the four Italian boxers who have so far qualified for the Beijing Games, heavyweight Clemente Russo, lightweight Domenico Valentino and flyweight Vincenzo Picardi, were born between Naples and Caserta. REUTERS/Max Rossi (ITALY)

Cleveland Cavaliers LeBron James tosses his mouth guard as he is pulled from the game after committing a foul against the Los Angeles Clippers during the first half of their NBA basketball game in Los Angeles November 11, 2007. REUTERS/Lucy Nicholson (UNITED STATES)

South Africa's Bryan Habana celebrates after scoring a try against Argentina during their semi-final Rugby World Cup match at the Stade de France Stadium in Saint-Denis, near Paris, October 14, 2007. REUTERS/Howard Burditt (FRANCE)

South Africa's Bryan Habana scores a try against Argentina during their semi-final Rugby World Cup match at the Stade de France Stadium in Saint-Denis, near Paris, October 14, 2007. REUTERS/Eddie Keogh (FRANCE)

South Africa's Bryan Habana scores a try against Argentina during their semi-final Rugby World Cup match at the Stade de France Stadium in Saint-Denis, near Paris, October 14, 2007. REUTERS/Eddie Keogh (FRANCE)

German heavyweight boxer Luan Krasniqi (R) and Brian Minto of the U.S. exchange punches as Minto looses his gumshield during their heavyweight WBO Intercontinental Championship fight in Stuttgart March 17, 2007. REUTERS/Alexandra Beier (GERMANY)

Rugby Union - Five Nations Championship - Wales vs Scotland - Cardiff Arms Park Stadium, Cardiff, Britain - February 2, 1996 Wales' Arwel Thomas replaces his gumshield REUTERS/Action Images