Settling in to the dentist’s chair, Greg Hutton expected nothing more than a numb mouth and a little discomfort once his troublesome tooth had finally been removed.

The former IT technician had gone in for a routine procedure, but it triggered a life-threatening illness that has blighted him since, leaving him partially deaf, unable to work or socialise and in constant pain.

For within two weeks of the extraction, Greg, now 62, developed infective endocarditis – a rare and potentially fatal heart infection: around 30 per cent of people die within a year of developing it.

Caused by bacteria that escaped from his bleeding gums during the procedure, it resulted in him spending months in hospital. He also had a heart attack – almost certainly as a direct result of the infection.

Yet all this trauma could have been avoided had his dentist given Greg antibiotics – such as amoxicillin or clindamycin – before his treatment.

That’s because Greg is one of tens of thousands of people in the UK who’ve had heart valve replacements, meaning even routine dental procedures – something as simple as a scale and polish – are potentially dangerous if it results in bacteria lurking in their gums reaching their heart.

Before that near-fatal trip to the dentist in November 2017, Greg was fit and active – running several times a week and playing football.

The father of one, who lives in Swansea with his wife Linda, 64, a retired human resources consultant, had only one health issue: he’d been born with a heart defect known as a bicuspid aortic valve.

It affects one in 50 Britons and means the valve that allows blood to move out of the heart has two flaps instead of three, reducing its efficiency and causing some people to become breathless easily.

Some may not even be aware they have this problem until they perhaps need the valve replaced, usually in middle age.

Greg was in his early 50s when he had an artificial heart valve fitted – one of the thousands who have this done every year. This puts them, and anyone with any type of heart valve damage, at high risk of developing infective endocarditis: that’s a total of around 400,000 people in the UK.

Giving pre-emptive antibiotics to these at-risk patients has been recommended by organisations around the world, including the American Heart Association and the European Society of Cardiology. Yet, in the UK, the advice of the National Institute for Health and Care Excellence (NICE) isn’t clear, say dentists. It states that prescribing antibiotics, previously routine for high-risk groups, should be done on a case-by-case basis.

On the day of his appointment, in November 2017, Greg’s dentist explained he wouldn’t be given antibiotics as NICE says it is no longer standard procedure – Greg, then unaware of the issues, was not worried.

However, two weeks later, he began to suffer a dull ache in his back. The pain worsened and got so bad he could only crawl into bed. Linda took him to A&E, where doctors diagnosed gastroenteritis, an intestinal infection.

But as the weeks passed, Greg got worse, suffering terrible night sweats. Over the next six months he lost 3st in weight and was back and forth to his GP and hospital for scans, probes and X-rays.

‘My GP thought it was leukaemia at one point, but nothing was showing in the blood test,’ he says. After six months Greg was diagnosed with an enlarged spleen – yet doctors couldn’t work out why. In despair, he began his own research online. He discovered it could be connected to infective endocarditis, triggered by dental treatment.

‘By this time it would take me a quarter of an hour to walk 100 yards because I was so breathless,’ says Greg.

‘When I told my GP he immediately sent me to hospital, where a consultant said if I hadn’t come in then I’d have been dead within two weeks because my heart wasn’t functioning properly due to the damage.’ Greg spent four months in hospital on intravenous antibiotics to kill the bacteria around the heart valve.

But he suffered a severe reaction to one of the drugs – gentamicin – which has left him partially deaf in both ears.

It got worse: in March 2019, Greg developed fungal infective endocarditis – an even more serious form of the heart condition that occurs when fungi enter the bloodstream and attaches to damaged heart tissue. And in 2020 he suffered a heart attack, most likely caused by the trauma his organ had endured.

There are around 1,500 cases of infective endocarditis in the UK each year, many due to dental-related infections.

NICE stopped routine antibiotic use for those at high risk in 2008. Martin Thornhill, a professor of translational research in dentistry at the University of Sheffield, published a study in 2015, that showed hospital admissions for infective endocarditis jumped afterwards.

‘Nobody has ever suggested that all patients undergoing any dental procedure should be given pre-emptive antibiotics,’ says Professor Thornhill.

Since 2023, NICE has had a link on its website endorsing guidance from the Scottish Dental Clinical Effectiveness Programme (SDCEP), which calls for high-risk patients to be prescribed the medication.

Professor Thornhill says it’s caused confusion among dentists in England and Wales. ‘They think the guidelines only apply to Scotland,’ he says. ‘And the SDCEP doesn’t include all dental procedures, which it should.

‘I was approached by the family of a Scottish patient with a prosthetic heart valve whose dentist told him that this wasn’t necessary for a dental cleaning [as per SDCEP advice] and, tragically, soon after he developed infective endocarditis and died.’

He adds: ‘My advice to patients is, if you fall into high-risk categories and need to have a dental procedure – even a scale and polish – you are at risk of infective endocarditis and you should be given antibiotics.

‘If your dentist won’t do it, find another dentist or get a cardiologist to write to them.’

Mick Armstrong, chair of the British Dental Association’s health and science committee, says: ‘People at risk of infective endocarditis should be regularly assessed for antibiotic cover when having dental procedures.’

A spokesman for NICE says antibiotics should not routinely be prescribed by dentists in case of heart problems, but insisted linking to the guidance in Scotland means at-risk patients are ‘readily identified’.

In 2024 Greg’s solicitors, Wolferstans, secured an undisclosed sum as compensation for his suffering. He is unable to work, ‘in near constant pain,’ and running is no longer possible.

‘I don’t go out much because even with hearing aids I struggle to hear,’ says Greg.

‘It’s hard to explain just how angry and frustrated I feel. I have been lucky, but it has been a horrible time for my family. And all so avoidable.’

• An earlier version of this article referred to research which we said found that only 78 per cent of dental patients who needed protective antibiotics had received them. In fact, the study focused solely on patients who had received prophylactic antibiotics, which we are happy to make clear, and we have removed reference to the research from the article.