Mouth guard use , principally to reduce dental injury , is strongly encouraged but not mandated within rugby union ; .
A New Zealand Rugby Union domestic safety rule mandates compulsory wearing of a mouth guard in all matches below international level in New Zealand .
Mouth guard use , principally to reduce dental injury , is strongly encouraged but not mandated within rugby union ; although a New Zealand Rugby Union domestic safety rule mandates compulsory wearing of a mouth guard in all matches below international level in New Zealand .