A new classification system may allow for earlier detection and more individualized treatment of gum infection or disease before the loss of teeth and supportive bone occurs, according to a recent study.

Researchers from Columbia University Medical Center have devised a new system for classifying periodontal disease based on the genetic signature of affected tissue, rather than on clinical signs and symptoms. Their findings were published recently in the online edition of the Journal of Dental Research.

Periodontal disease is currently classified as either "chronic" or "aggressive," based on clinical signs and symptoms, such as severity of gum swelling and extent of bone loss, according to a press release.

"However, there is much overlap between the two classes," Panos N. Papapanou, study leader and professor and chair of oral and diagnostic sciences at the College of Dental Medicine at CUMC, said in a statement. "Many patients with severe symptoms can be effectively treated, while others with seemingly less severe infection may continue to lose support around their teeth even after therapy. Basically, we don't know whether a periodontal infection is truly aggressive until severe, irreversible damage has occurred."

To examine this further, Papapanou turned to cancer as a model. In recent years, cancer biologists have found that, in some cancers, clues to a tumor's aggressiveness and responsiveness to treatment can be found in its genetic signature. To determine if similar patterns could be found in periodontal disease, researchers performed genome-wide expression analyses of diseased gingival (gum) tissue taken from 120 patients with either chronic or aggressive periodontitis. The test group included both males and females ranging in age from 11 to 76 years.

Researchers found that, based on their gene expressions, patients fell into two distinct clusters.

"The clusters did not align with the currently accepted periodontitis classification," Papapanou said.

However, the clusters did differ with respect to the extent and severity of periodontitis, with significantly more serious disease in Cluster 2.

 Their research also found higher levels of infection by known oral pathogens, as well as a higher percentage of males, in Cluster 2 than in Cluster 1, in keeping with the well-established observation that severe periodontitis is more common in men than in women.

"Our data suggest that molecular profiling of gingival tissues can indeed form the basis for the development of an alternative, pathobiology-based classification of periodontitis that correlates well with the clinical presentation of the disease," Papapanou said.

Their next goal is to conduct a prospective study to validate the new classification system's ability to predict disease outcome.