At least 1.8 million people aged 65 and over could have an urgent dental condition, according to a new report.
Dentists have raised concerns about the impact conditions such as dental pain, oral sepsis - an infection that can lead to blood poisoning - and extensive tooth decay are having on older people's quality of life.
The Faculty of Dental Surgery (FDS) is calling for health and social care professionals to receive training in oral health, and for regulators to make standards of oral care part of their assessments of hospitals and care homes.
A report published on Tuesday estimates at least 1.8 million people aged 65 or over across England, Wales and Northern Ireland have an urgent dental condition, which could rise by more than 50% by 2040.
Professor Michael Escudier, dean of the FDS at the Royal College of Surgeons, described the figures, calculated using the latest available data, as "terrible".
"We are letting older people down at a time when they need the most help by not having a joined-up strategy for improving access to dental services for older people," he said.
"Many of us know what it's like to have excruciating tooth or gum pain. It puts you off your food and makes it difficult to do daily tasks.
"For older people, the effects are even worse. It can be very isolating, making people reluctant to socialise with friends and family, and will have a significant impact on their quality of life."
Poor oral health is linked to conditions in older people such as malnutrition and pneumonia, said Prof Escudier, who added: "We need to work together to ensure improvements in oral healthcare for older people.
"Dental health needs to be viewed as part of older people's overall health, with health professionals and social care providers being trained to recognise and deal with problems."
Andrew Kaye, head of policy and campaigns at older people's charity Independent Age, said: "The finding that 1.8 million or more older people have an urgent dental problem is truly shocking.
"There needs to be a significant step-change in the way health and care services view oral health."
Sara Hurley, Chief Dental Officer for England, said: "Good dental health matters at every age and it is the responsibility of all health and social care professionals to ensure older people in their care have timely access to dental treatment, whether they are in a hospital, nursing or residential care homes or living independently.
"An effective daily dental hygiene plan is essential and will help to avoid unnecessary tooth loss, pain and disease whilst maintaining and improving oral health."
She said Health Education England deliver a Mouth Care Matters programme, which is available to all health and social care professionals, that has already been adopted by 13 trusts across England.