Protecting tight bites.

Protecting tight bites

Periodontal disease, the leading cause of tooth loss in adults, is an inflammatory process generating enzymes that attack the rope-like collagen fibers anchoring teeth in place. Dentists usually diagnose the disease by the presence of loose teeth and gum inflammation or the formation of pockets between the teeth and gums. By the time such symptoms appear, significant tooth detachment may have occurred, notes University of Toronto biochemist Jaro Sodek. But his preliminary studies indicate that a simple diagnostic assay for the disease may be on the horizon.

Through a process called remodeling, collagen fibers can break and reform, permitting teeth gradually to move and adapt to changing conditions in the mouth. The process begins with single enzyme-initiated breaks in the protein chain of selected collagen fibrils. The initiating enzyme -- one of the neutral metalloendoproteinases (NMPs) -- not only causes the collagen fibrils "to begin unraveling," Sodek says, but also opens them up to attack and breakdown by other NMPs. These remodeling NMPs are produced by healthy cells in periodontal tissue--the same cells that will later direct the synthesis of new teeth-anchoring collagen.

In periodontal disease, NMPs produced by inflammatory cells--largely white blood cells--trigger a massive breakdown of collagen. And nlike the cells controlling remodeling, inflammatory cells do not replace the collagen they degrade.

Sodek and his co-workers have been studying the NMPs in sulcal fluid exuded from between the teeth and gums as a possible marker of developing periodontal disease. In a study with beagles, they found that levels of such enzymes "could be related to the progression of [periodontal] disease," Sodek reported last week. In another study following teens with localized juvenile periodontitis (characterized by rapid tissue breakdown) for six months or more, treatment reduced NMP activity.

Finally, an ongoing study is analyzing sulcal fluid collected in a mouth rinse. After flushing excess saliva from the mouth, subjects swish distilled water through their teeth and spit it out to be assayed. The researchers have found high levels of active enzymes in people in whom periodontal-tissue breakdown was later confirmed. Inactive enzymes were washed from individuals with inflamed gums but no breakdown of ligaments supporting teeth. And rinses from healthy people showed high levels of proteins that block NMP-enzyme activity. Sodek says data from the several dozen individuals screened thus far suggest the assay is sensitive enough to aid in the early detection of even largely asymptomatic periodontal disease.