The research by fourth-year dental student Amy Chatfield was designed to gather information from parents and players about mouthguard use.
Of the almost 200 players who responded to the survey, 92.6% said they always wore a mouthguard for the whole game.
However, at practices the percentage of wearers dropped to 62.6%.
Miss Chatfield said some of the respondents indicated that at practice there was less contact involved, but accidents were unpredictable and injuries did occur during practice.
Some rippa rugby parents also saw little point in providing their child with a mouthguard for a one or two-day tournament.
"Whether a child is playing rugby for a season, or just for a one-off game, the danger of an injury is still there."
She pointed out that teeth injuries might never heal completely and could require costly treatment for the rest of the injured person's life.
Miss Chatfield, whose research was funded by the Child Injury Prevention Foundation of New Zealand and the University of Otago's School of Dentistry, praised those involved with rugby for the efforts they had made to promote mouthguard use.
She made reference to earlier research which showed rugby union dental injury claims had decreased by 43% over eight years following the introduction of mandatory mouthguard use, while claims from touch rugby, where use was optional, had increased.
About 40% of parents in Miss Chatfield's research got their children's mouthguards through their rugby club.
Many rippa rugby parents advised their rugby club provided their child with a mouthguard as part of the registration, something which made the guards likely to be seen as part of the "core equipment and not an added extra".
This might make it more likely players would wear them, she said.
It also saved parents the extra trouble of purchasing a mouthguard elsewhere.
Parents and players were clear about where responsibilities lay for mouthguard use, with almost all respondents saying it was the players' responsibility to ensure they wore one.
As one parent put it "it is the child's responsibility to wear it; parent's responsibility to provide it".
It was encouraging that only a couple of players noted difficulty using a mouthguard.
Miss Chatfield plans to share the results of her survey with the rugby union in the hope it may be useful to help it assess the effectiveness of its injury prevention programme in this area.
