A new dental center is built to welcome patients with special needs and those in wheelchairs, who often run into obstacles elsewhere.

Cheryl Closs, a mother of four from West Islip, N.Y., wanted to save her daughter Bella’s two front teeth. They were badly decayed, and one dentist wanted to just pull them out. But Ms. Closs was having none of it.

Bella, who is 15 and in 8th grade, has special needs and uses a wheelchair.

“They are quick to pull a child’s teeth that is special needs,” Ms. Closs said. So she began a search for a root-canal specialist. She would take Bella out of school for the day and her husband would drive them to whichever borough for a dental appointment. But they took Bella to at least eight dentists and root-canal specialists, all of whom declined to treat her. Some “didn’t even look at her teeth,” Ms. Closs said. “This has happened so many times.”

Bella favors pigtails and Wonder Woman T-shirts. She smiles a lot but doesn’t say much and doesn’t like being touched, let alone restrained. She has a genetic disease called fucosidosis, which is deteriorating her brain function. Getting an X-ray or having her teeth cleaned can be challenging, requiring more time or more hands on deck to hold her head or flailing arms.

And many dentists can’t — or won’t — treat patients with disabilities. Some cannot physically accommodate a large wheelchair, “or they don’t feel comfortable treating the patients,” said Dr. Rita Bilello, the dental director at Metro Community Health Centers in Brooklyn, Staten Island and the Bronx.

Historically, pediatric dentists were taught how to treat patients with special needs, but general dentists weren’t. That means a child with autism might get regular checkups, but not necessarily an adult.

However, in 2006, a new standard for dental programs went into effect. The Commission on Dental Accreditation mandated all students had to be able to competently assess the treatment needs of special-needs patients. But as of 2012, less than three-quarters of dental schools have predoctoral students actively involved in their treatment, according to a study in the Journal of Dental Education.

Access remains a formidable problem for patients with special needs. But the N.Y.U. College of Dentistry’s Oral Health Center for People With Disabilities offers a new option for patients like Bella. It is the rare facility that treats adult and pediatric patients across the spectrum of disabilities — those with developmental delays like autism, intellectual disabilities, or conditions like cerebral palsy and dementia. It has two operating rooms where patients who can’t sit still can be sedated.

Besides expanding access for patients, N.Y.U.’s center aims to send all of its graduates into the world with the skills and confidence to care for special-needs patients.

Dr. Ronald Kosinski, a pediatric dentist and the director of the new center, didn’t mince words. Patients with disabilities face roadblocks because “people are afraid of them,” he said. “They are not looked at like people. We need to train dental students to stop throwing their hands up and to start embracing them.”

N.Y.U. educates roughly 10 percent of the nation’s dentists, so the new center could have an outsize impact. “You may not realize you’re capable of treating a schizophrenic in a wheelchair with cerebral palsy until you’re given an opportunity to try,” Dr. Bilello said.

Cheryl Closs, Bella’s mother, left, arriving at the N.Y.U. College of Dentistry for an appointment with Dr. Ronald Kosinski.CreditJackie Molloy for The New York Times

Cheryl Closs, Bella’s mother, left, arriving at the N.Y.U. College of Dentistry for an appointment with Dr. Ronald Kosinski.CreditJackie Molloy for The New York Times

There’s no shortage of need. Roughly 915,000 people are living with a disability in New York City alone, according to the Mayor’s Office for People With Disabilities. That’s potentially a lot of untreated teeth.

“Access to care is a huge, huge problem,” said Dr. Alan N. Queen, the attending-in-charge of a special-needs dental clinic at NewYork-Presbyterian Queens Medical Center. “The problem is that special-needs patients, they are difficult to treat compared to your average patient, and unfortunately there’s no allowance for that in how insurance pays.”

Dr. Queen, who is also in private practice in Flushing, Queens, said that to treat a Parkinson’s patient with tremors, for example, he needs one assistant to “hold their head still, another to retract their tongue, another assistant suctioning, and then me doing all the dental work.” Dental practices should get additional reimbursement for such cases, he said.

Last October, the American Dental Association updated its code of ethics to specify that patients with disabilities should not be denied dental service. At the very least, the code said, dentists who can’t treat a patient must refer them to another professional.

Ultimately, that’s how Bella caught a break. This spring, when an employee of a dental office called to cancel an appointment the day before because of Bella’s wheelchair, Ms. Closs started sobbing: “You made me wait six months.” An office manager got on the phone and found a solution.