Footballers from top clubs including Hull City and Sheffield United have poor dental health, which affects their performance, researchers say.
Almost four out of 10 professional footballers have dental cavities, while one in 20 has irreversible gum disease.
Others suffer infections, while many experience regular toothache, found the study, published online in the British Journal of Sports Medicine.
This poor level of dental health affects footballers’ performance and wellbeing, and the sport “urgently” needs to promote better dental care, experts behind the research said.
The dental health of footballers appears to be worse than for the general population, though experts have yet to pinpoint the exact reasons why.
Many footballers drink sports drinks several times a week, although evidence is “unclear” on whether this is to blame.
The study involved 187 footballers from eight clubs - Hull, Manchester United, Southampton, Swansea City, West Ham, Brighton and Hove Albion, Cardiff and Sheffield United.
Six dentists checked the tooth and gum health of every player - equivalent to more than 90% of each senior squad - and each footballer was asked about the impact of dental health on their personal and professional lives.
Almost three-quarters of players (73%) had been to the dentist within the past 12 months and 22% reported a history of trauma to their teeth or face due to the sport.
Some 64% of players said they drank sports drinks at least three times per week, while 5% used tobacco, mainly smokeless or chewing tobacco.
Researchers found that 37% of the footballers had at least one tooth affected by decay while 77% had needed fillings, with some needing more than five.
Overall, 84% of all footballers had at least one decayed or filled tooth.
Dental “erosion”, where the tooth is worn away by acid, was present in 53% of footballers, while 77% of footballers had half of their mouth affected by gingivitis (inflammation of the gums). In 5% of footballers, this was moderate to severe and irreversible.
Some 8% of footballers had at least one ulcer, abscess or open sore, while one in 10 had regular toothache and 16% experienced pain in their mouths. Over a quarter (27%) had sensitivity to hot or cold drinks.
More than 45% of footballers said they were “bothered” by their oral health, with 20% reporting an impact on their quality of life and 7% reporting an impact on training or performance.
The researchers, including from University College London, said several things contribute to poor dental health, including food and drink and how much emphasis is placed on oral health in sport.
Some teams had worse teeth than others, suggesting there is a role for preventing tooth decay and introducing formal screening in clubs, they said.
“Few teams integrate oral health promotion within overall medical care, and there is therefore lack of ongoing support and reinforcement of this health area for the athletes,” they wrote.
“Oral health of professional footballers is poor, and this impacts on wellbeing and performance. Successful strategies to promote oral health within professional football are urgently needed.
“Furthermore, this study provides strong evidence to support oral health screening within professional football.”
The experts stressed the “relationship between sports drinks and dental erosion remains unclear”.
One review, which was just on children, found no link, although another study on 3,000 people found drinking sports drinks was linked to tooth decay.
The footballers were typically aged 24, though they ranged in age from 18 to 39.
The British Dental Association’s scientific adviser, Professor Damien Walmsley, said: “If your favourite soccer team isn’t doing well, you might want to ask them if they are they looking after their teeth.
“The high degree of erosion seen in footballers’ teeth is likely to reflect a high consumption of either ‘sports’ or fizzy drinks following strenuous exercise. Footballers, like the rest of us, would be better off drinking water to quench their thirst after strenuous exercise rather than sports or fizzy drinks that place teeth at risk.
“Contrary to expectation, sports drinks are rarely a healthy choice. They don’t necessarily contain high amounts of sugar, but the high levels of acidity can cause irreversible damage to teeth.
“The acid in these drinks breaks down the tooth’s enamel, the shiny outer layer of your teeth, causing them to become sensitive to temperature changes and touch. On the other hand, many fizzy drinks do contain sugar and this will place teeth at risk of developing cavities or teeth decay.”