But the seven-year project by Australian researchers suggests there is no need to act so quickly. With early-stage decay taking four to eight years to eat into the tooth, there is plenty of time for the rot to be halted in its tracks.
Led by Professor Wendell Evans, the team tracked the dental health of 900 patients at almost 20 practices.
Half were treated as normal and half with the Caries Management System devised by the professor.
For these patients, instead of filling teeth that were starting to decay, the dentist instead applied a high-strength fluoride varnish to their surface. Patients were then told to brush twice daily with a fluoride toothpaste and to avoid sugary snacks and drinks.
Those who followed these steps found decay was stopped and even reversed, teeth hardened and the need for filling was cut dramatically, the journal Community Dentistry and Epidemiology reports.
Professor Evans, of the University of Sydney, said: "This research signals the need for a major shift in the way tooth decay is managed by dentists.
"Our study shows that a preventative approach has major benefits compared to current practice. For a long time it was believed that tooth decay was a rapidly progressive phenomenon and the best way to manage it was to identify early decay and remove it.
"However, 50 years of research studies have shown ... it takes an average of four to eight years for decay to progress from the tooth's outer layer to the inner layer.
"That is plenty of time for the decay to be detected and treated before it becomes a cavity and requires a filling."
Commenting on the study, Professor Damien Walmsley of the British Dental Association said:
"The study is interesting because it confirms ... that tooth decay is a preventable disease and highlights the simple steps that everyone can take to reduce their risk of developing decay and therefore avoid the need for fillings altogether.
"If everyone adopted these basic measures, then the need for drilling teeth would gradually disappear."
- Daily Mail