Three of the region’s best-known charitable foundations are using a challenge grant to rally Charlotte behind a free dental clinic that could be the largest of its kind in the nation.

Foundation for the Carolinas, The Leon Levine Foundation and the Carolinas HealthCare Foundation are each offering $20,000 for the annual clinic if the community matches the money dollar for dollar.

That $120,000 would cover most of the projected cost for the 2012 North Carolina Missions of Mercy-Charlotte clinic, which will provide about 1,000 dental professionals to give free treatment to low-income and uninsured people.

Organizers say the clinic’s all-volunteer staff provided $1 million in free dental care to 2,145 adults last year during its three-day run at the Charlotte Convention Center. This year’s clinic, to be held in December, is expected to be even bigger, officials said.

Brian Collier of Foundation for the Carolinas says the grant offer is a way of pointing out that the community often overlooks dental care as a pressing need for low-income people. Charity dollars typically go toward food, shelter and utilities assistance programs.

“In reality, dental health impacts almost every aspect of our life, including the ability to gain meaningful employment, said Collier.

Kenneth Owen, one of the dentists who organized the Charlotte clinic, sees the grant as a pat on the back for the program, which was pieced together last year with smaller donations of cash, supplies and free space at the convention center.

So far, donors have given more than $10,000 toward the match, he said.

The Missions of Mercy clinic program is an outreach effort of the North Carolina Dental Association, which has been providing free dental care at similar clinics across the state since 2003.

Last year marked the first time the program expanded to Charlotte. The need here was underscored when people began camping outside the convention center last December to get help.

Hundreds had to be turned away. However, organizers managed to squeeze in an additional 500 patients, setting a state record for the most dental patients helped by the program over the 36 hours.

Another dentist behind the clinic, Evan Miller of Charlotte, says a priority is to help those who are in such pain, they can’t eat properly.

Patients run the gamut, he said, from those who’ve never seen a dentist to those who had dental care before the economic downturn.

“Those are the ones who were employed a year ago, but lost their job and no longer have the means,” said Miller.

Another dentist, Alvin Goodman, noted the clinic can be quite dramatic at times, with treatment often ending in hugs.

Among the most moving things he saw last year was a fragile woman in her 80s, who waited in line 21 hours to see an oral surgeon.

“She weighed about 90 pounds and was trembling because she was in so much pain,” Goodman said. “I took her to the front of the line. There are so many like her at the clinic in desperate need.”