Growing up in an orphanage in Haiti, Thomy Elusme brushed his teeth regularly and never got a cavity.

Yet by his teenage years, a few teeth had started to become loose and one eventually fell out. After coming to New Jersey to live with a host family, the soft-spoken 20-year-old had to have a second one pulled.

Elusme suffers from a condition all too familiar to periodontist Daniel H. Fine, who examined the young man last month at the Rutgers University School of Dental Medicine in Newark, N.J. For more than 30 years, Fine has been tackling the mystery of why, through no apparent fault of their own, up to 2 percent of black youths have loose teeth.

Research by Fine's team and others indicates genetics plays a central role in this aggressive periodontitis, which is all the more worrisome in low-income communities with poor access to dental care. Yet now, with the help of rapid-screening techniques and other tools of modern microbiology, Fine thinks he can catch it and treat it before patients even notice a problem.

If the Rutgers professor has his way, all inner-city teens will someday spit into a tube at the school nurse's office. Then the nurse would test their saliva for the presence of a telltale protein that, according to Fine and colleagues, seems an early-warning sign of bone loss.

"The nurse might be able to give them something right then and there so they can prevent the disease from occurring," said Fine, a gregarious sort who favors bow ties. "That's our hope."

Fine and his team recently won a $3.2 million grant from the National Institutes of Health to study the problem further. He seeks to enroll several hundred children from Newark and other urban school systems in North Jersey and follow their dental health for two years.

If past evidence is any guide, those predisposed to periodontal disease enjoy a silver lining of sorts. They will develop few, if any, cavities on the smooth surfaces between teeth.

Researchers do not entirely agree on why that is, other than it seems related to some genetic quirk that dictates the patient's response to various oral bacteria.

Fine's own research points to a variant form of a salivary protein that seems to have the knack for warding off the bacteria that cause cavities. But he thinks that because this one type of bacteria is cleared out in these patients, that allows others to gain a foothold - specifically, a trio of bacteria species associated with periodontal disease.

Denis F. Kinane, dean of the University of Pennsylvania School of Dental Medicine, is not convinced that theory is correct. But he praises Fine's enthusiasm for finding a solution to a real problem among black youth. The condition is rare among white youth.

"We need people like Dan Fine to get people interested and excited about these things," Kinane said.

One person with keen interest in the answer is Elusme, the patient from Haiti, who had little exposure to dentistry before moving to the United States in December.

"I want to know what's happening," Elusme said after Fine and Rutgers colleague Thomas A. Bissell examined his teeth. "I find that interesting."

Elusme lives with Eric and Heather Koby in Chester, N.J., in Morris County. Heather Koby met the young man during a Christian mission trip to Haiti, soon after the 2010 earthquake, and was drawn to his sweet disposition.

The couple had adopted three other children and tried to do the same for Elusme, but he was denied a visa on multiple occasions. They contributed to his school tuition in Haiti, then finally learned in the fall that his latest visa application had been granted.

Elusme was too old for formal adoption, but the Kobys consider him a family member and are sending him to the County College of Morris, where he studies business.

Morris County dentist Joseph J. Gaudio agreed to treat Elusme pro bono. When he saw Elusme had periodontal disease, he referred him to Bissell, who has a practice not far from the Koby home and who also agreed to offer his services at no charge.

Elusme is not a formal participant in the new Rutgers study, as it is aimed at children ages 11 to 17, but he has agreed to let researchers test his samples for general research purposes.

Initial results indicate his mouth harbors an especially potent form of one of the bacteria Fine blames for periodontal disease.

Treatments for the disease typically include antibiotics. In Elusme's case, which was advanced, Bissell used a special laser to remove calcified plaque from the roots of his teeth; some clinicians prefer to use a scalpel.

Gaudio also used adhesive to bond Elusme's loose teeth to their more stable neighbors.

In the new study, the Rutgers researchers will not let anyone get to the point of visible symptoms. Patients will be seen every three months and will be treated at the first sign of the telltale protein in their saliva.

And if someday Fine can spread that technique to every nurse's office in big-city school systems, it will mark the end of a long road.

"We've been studying this thing for the last 30 years," Fine said. "It's only in the last few years that the technology has blossomed."