South Hams has the highest proportion of five-year-olds with dental decay in the South West, new figures suggest.
The Office for Health Improvement and Disparities data relates to five-year-olds with any enamel and dentinal decay.
It reveals an estimated 49.6% of five-year-olds in South Hams had dental decay in the 2023-24 academic year – the highest rate in the South West.
Across England, this stood at 26.9% last year – a slight improvement from 29.3% in the previous survey of the cohort in 2021-22.
The British Dental Association said there has been "no progress" on the rollout of Labour manifesto pledges to "fix the failed contract fuelling the crisis in NHS dentistry" or to deliver prevention programmes in schools.
Chairman Eddie Crouch said: "This oral health gap was made in Westminster, with children paying the price for official failure to take dentistry seriously.
"A new Government calls this 'Dickensian', but it will take deeds not words to turn this around."
David Fothergill, chairman of the Local Government Association's community wellbeing board, said untreated dental issues are one of the leading causes of hospital admissions for children and teenagers, with over 31,000 operations in 2023 to remove rotten teeth.
He added: "Alarmingly, these figures highlight stark inequalities in oral health. Children living in the most deprived areas are more than twice as likely to experience dental decay compared to those in the least deprived areas."
He urged the Government to use the upcoming spending review to invest in council-run oral health improvement programmes, which he says are proven to help children develop healthy oral hygiene habits.
The figures also revealed significant regional disparity, with the level of decay ranging from 23.3% in the East of England to 36.8% in the North West.
In the South West, 24.2% of five-year-olds had dental decay.
Dr Charlotte Eckhardt, dean of the faculty of dental surgery at the Royal College of Surgeons, said the rate of children suffering from a preventable condition is "concerning".
She added: "Supervised toothbrushing programmes (STPs), which the Government has said it will implement, offer a glimmer of hope, but their roll-out is uneven across the country.
"STPs have proven to reduce dental decay within a single year after children have been enrolled."
Health minister Stephen Kinnock said: "It is appalling that nearly a quarter of our young children have been left to suffer painful tooth decay when it is so easily prevented.
"And it is scandalous that the New Patient Premium – set up at a cost of millions to improve access to treatment for patients – has had next to zero impact."
He added plans are being brought forward to "fundamentally reform NHS dentistry", including an early intervention programme with supervised toothbrushing in deprived areas.
"We'll also deliver an extra 700,000 urgent dental appointments to help those who need it most, and will reform the dental contract to encourage more dentists to offer NHS services to patients," he said.