36 Under 36 2009: Dr. Robert Grunstein, 35

 Dr. Robert Grunstein has always been a car and truck guy. So when he heard that an old municipal fire truck was up for sale ("the holy grail for car guys," he says), he bought it. The fire truck cost him $5,000; converting it into a mobile dental unit and taking out the water tank set him back $50,000. "It had a new motor and perfect transmission," Grunstein gushes. It’s the perfect vehicle, he says, for combating the "tsunami of bad teeth."

For the past five years, Grunstein has hopped on the fire truck — the "Dental Rescue Unit"— two mornings a week and visited local schoolchildren in 60 schools in Paterson, Passaic, Clifton, and other Northern New Jersey towns. The kids join him on the fire truck, where Grunstein’s brother, Gabi, puts on a half-hour puppet show promoting good dental hygiene. Then Grunstein examines each child’s teeth, sending them home with report cards listing the number of cavities they have. The worst offenders — those with more a dozen cavities or more— are brought to the nurse, who phones their parents. Grunstein doesn’t receive a penny for his visits. "It’s worth it," he says, "because it’s so satisfying."

Often, the very next morning, Grunstein will find those kids with the most cavities seated in his dental chair. "My patients are really, really grateful," he says. "Often, parents don’t know that children’s dental care may be covered by Medicaid."

In fact, only 770 of the 7,000 dentists in New Jersey accept Medicaid. That’s partly because New Jersey’s Medicaid reimbursement rates for dental care are as low as a third of New York rates, Grunstein says. So there aren’t many other dentists willing to accept Medicaid.

"This is where I felt I was needed most as a doctor," says Grunstein, who claims he took bioethics twice while studying at Yeshiva University. "It’s sort of like how a nurse in the ER looks at triage: you treat those who are most in need first."

Dentistry runs in the family: Grunstein’s mom is a dental technician and has a home office located next door to his bedroom. "I grew up with the sound of the dental drill in my ear," he says.

Love fire trucks? Visit the fire truck-shaped front desk at Grunstein’s new Passaic office, which features real tires and hubcaps. Side job: While in dental school, Grunstein rebuilt jeeps to make extra money.