A dental expert has claimed treatments such as braces can have "life-altering" results for adult patients.

Dr Brendan Cooney was speaking after research from the American Association of Orthodontics revealed that roughly 25 per cent of all orthodontic patients treated in the last 20 years have been adults, the Albany Times Union reports.

While the majority of people choose to have braces fitted as a form of cosmetic dentistry, recent studies have suggested a growing awareness of the health benefits associated with straighter teeth.

"Braces make life-altering changes and adults are very motivated to make those changes happen, as quickly as possible," Dr Cooney told the newspaper.

Invisalign treatment, which requires people to wear a set of invisible braces for between 20 and 22 hours a day, has become increasingly popular among adults.

Patients are given a new set of aligners every two weeks or so, with the full treatment process typically lasting for about 12 months.