CITIZENS Advice has reported a 9 per cent increase in calls from people with dental care complaints in the last year.
The national charity said it fielded complaints from around 4,000 people in England and Wales between April 2015 and March 2016.
Substandard service was the biggest issue reported and an analysis of 354 of these cases revealed that around 75 per cent concerned treatment that caused the patient further problems. In a quarter (23 per cent) of those cases patients also said dentists refused to offer a refund or a free-of-charge repair.
Citizens Advice is calling on dentists to follow the rules by correcting their mistakes free of charge instead of passing costs onto patients.
Gillian Guy, Chief Executive of Citizens Advice, said: "While many people get a good service from their dentist, some patients are having treatments that leave them with a new problem like a loose or painful filling or healthy teeth that have been cracked.
"Not only do they have to undergo further treatment to fix the problem - in some cases dentists are breaking the rules by wrongly asking patients to pay the extra costs. If a dental treatment causes more problems for the patient, the law states that in most cases the dentist should be offering to repair this at no extra charge. Asking patients to pay could put their health at risk if they are unable to afford the further treatment."
But Dr Nigel Carter of the Oral Health Foundation said the claims made by Citizens Advice are "enormously misleading" in failing to highlight that the vast majority of dental treatments in the UK are carried out with no adverse issues.
He said: "Recent government figures show that there were 9.9 million NHS dental treatments carried out in England and Wales in the last quarter alone, these figures do not take into account private treatment but these would take it well over 15 million.
"Citizens Advice refers to helping with 4,000 problems over the last year, this equates to less than a tenth of one per cent of treatments in the same period, and is an attempt to frighten the public and paint dentistry in a negative light.
"By ignoring the bigger picture of dentistry in the UK they are not helping the one in four people who are already incredibly nervous about visiting the dentists and fuelling fear in even more people. This is an issue which has contributed to more than 80 per cent of adults suffering from dental decay and most (nine in 10) adults experiencing a degree of gum disease at some time in their life. Regular visits to a dentist is a big factor in stopping this.”