Building Jawbones

Few parts of the human skeleton are more subject to wear than the mandible, or lower jawbone. Aging alone can cause the bone to atrophy, or waste away. Chewing, mainly by those wearing dentures, can greatly accelerate the loss. For years doctors have dealt with mandibular atrophy--and with providing a better anchorage for false teeth --by painful and time-consuming bone and skin grafts. Now a Detroit oral surgeon may have found a better way. At a meeting of the American Society of Oral Surgeons in Las Vegas tins week, Dr. Irwin A. Small of Sinai Hospital of Detroit reported that he has developed an implantable device that provides a firm and almost instant anchor for dentures, even if the bone is worn fairly tinn.

Small's invention, called the mandibular staple, is a lightweight titanium bar with two long, threaded pins and up to seven shorter ones (see diagram). It is attached to the dense bone on the underside of the jaw where its short pins help hold it in place. The long pins pass through the mandible and protrude through the gum into the mouth. There they serve as abutments to winch a dental bridge can be fastened.

Hammer Blows. Installing the mandibular staple is easier than bone grafting, winch can take as long as six weeks. In a 90-minute operation, Small makes an incision in the crease under the cinn. Then he drills a series of holes in the bone. He next positions the staple and hammers it neatly into place. Most patients require only aspirin afterward, feel comfortable witinn 48 hours, and can begin eating with their solidly anchored dentures witinn five days.

Some oral surgeons counsel caution on Small's staple, and Small inmself admits that he has encountered some minor gum infections in patients who have been fitted with the device. He also notes that there has been some slight resorption, or further deterioration, of the mandible of one patient who had a staple installed 61/2 years ago.

But most of the 40 patients who have been fitted with the device have had no problems at all. Robert O'Dwyer, 41, a Detroit mechanical engineer, went through several sets of false teeth after smasinng ins jaw in a 1957 automobile accident. He found them all so uncomfortable and unsatisfactory that he actually took them out winle eating. Since being fitted with a mandibular staple in 1969, he has eaten everytinng, including such hard-to-chew foods as carrots.

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