G.S. Mudur, New Delhi, April 3: Chronic irritation of the mouth from ill-fitting dentures may be a risk factor for oral cancer, Indian doctors have said after a research review that explored links between chronic mucosal trauma and cancer.
Doctors at the Tata Memorial Centre, Mumbai, said denture-related sores might be colonised by candida, a fungus that may induce chronic inflammation of the mucosa, which has been hypothesised as an oral cancer risk.
Their review, which examined 22 studies from various countries, probed the lingering uncertainty over the role played in oral cancer by chronic mucosal irritation from poor dentition, missing or sharp teeth, or ill-fitting dentures.
Oncologists estimate that about 100,000 people are diagnosed with oral cancer in India annually.
About 80 to 90 per cent of oral cancers are associated with the use of tobacco (chewed or smoked), areca nut or alcohol. Researchers have been speculating whether longstanding mucosal irritation might be an additional risk factor, explaining the 10 to 20 per cent of cases without history of known risk factors.
"We find a statistically significant link between ill-fitting dentures and the risk of oral cancer," Pankaj Chaturvedi, professor and head and neck surgeon at Tata Memorial, told The Telegraph.
Chaturvedi said: "Ill-fitting dentures may damage the mucosa 24 hours a day, even during sleep, and contribute to trauma."
Animal studies have suggested two mechanisms how chronic trauma might contribute to cancer. Persistent mechanical irritation might lead to genetic damage and push cells to turn cancerous, or cause inflammation and biological stress leading to cancer.
"Many people with ill-fitting dentures often fail to go to dentists for follow-up adjustments," said Chaturvedi. "Many tend to live with some discomfort which may lead to mucosal trauma."
Chaturvedi and his colleagues, Hitesh Rajendra Singhvi and Akshat Malik, have published their findings in the Indian Journal of Medical Paediatric Oncology.
The Dental Council of India estimates the country has about 1.5 lakh registered dentists, most of them in cities and towns while vast proportions of the rural population lack prompt access to dental services.
Doctors say that villagers who might get their dentures in towns do not always return for follow-up visits to dentists.
Chaturvedi said that large proportions of the population tend to neglect their oral health. "Low levels of awareness about the importance of oral health among members of the public and even health care providers has led to continued neglect of dental care," he said.
The Tata Memorial doctors said that while mucosal injury might also result from sharp or broken teeth, the "available evidence" was not "significant enough" to count them as a risk factor for oral cancer.
Their review has not found any association between the duration of denture use and the development of oral cancer.
Nearly a decade ago, Japanese researchers had through a large study involving over 5,000 patients detected a strong link between tooth loss and the increased risk of oesophageal, oral and lung cancer. They had found that the larger the number of teeth lost, the greater the risk of the cancers.