A group of Auckland dentists is hoping to put a smile on the faces of the city's most needy.

More than $30,000 worth of free dental treatment is being offered via the Smile for Christmas campaign.

For every new 'like' on the Smile Dental New Zealand Facebook page, $5 will be donated to the campaign.

Otahuhu dentist Dr Jacky Lam said the Auckland City Mission is helping run the initiative.

"We try to reach out to the needy ones a lot of them are homeless people and they're not even able to afford food."