Rugby concussions not prevented by equipment: MD
Amateur Sports Info
Mouth guards and headgear don't help prevent concussions in rugby players, but education and rule changes do, a new review suggests.
Source: CBC | Amateur Sports News
From my experience of playing the game nothing really will completely prevent the concussion taking place in a full contact sport like rugby.
Yes rule changes can try and help but it will still happen, mouth guards give a greater protection than the head gear.