Wednesday, July 21, 2010

Toothless no more: team aims to reduce rejection of implants

Don Brunette may well find himself named the patron saint of toothless hockey players.

An oral biologist in the Faculty of Dentistry, Brunette seeks to create a better dental implant by understanding how cells behave around different types of implant surfaces.

Dental implants consist of a titanium screw or cylinder that is inserted into the jaw. The post serves as base onto which the replacement crown or bridge is attached.

For his research, Brunette draws upon sophisticated methods of microfabrication and nanofabrication which can produce precisely characterized surfaces. He can then examine how cells respond to specific features and shapes of the implant’s surface – that is, its topography – at the nanometer and micrometer scales.

Brunette’s current line of inquiry evolved from his breakthrough work with titanium surfaces during the 1980s. At that time, Brunette was the only researcher in the world studying microfabricated surfaces and cell behavior. He observed that microscale grooves could direct cells in desired directions and also encourage bone growth.

A Vancouver-based implant manufacturer marketed implants based on the principles developed in Brunette’s research, and more recently, a U.S. firm is using lasers to produce grooves on dental implants.

Of particular interest to Brunette are cells called macrophages, which in Greek means “big eater.” Macrophages are among the first cells to appear at the site of a wound to clean up bacteria, explains Prof. Brunette. They also orchestrate the body’s response to foreign objects such as implants.

“The intent is to develop surfaces that induce macrophages to stimulate healing rather than destructive inflammation,” says Brunette.

Along with Dentistry Assoc. Prof. Douglas Waterfield, Brunette recently received more than $685,000 from the Canadian Institutes for Health Research for their innovative study.

The investigators will explore cell structure, migration and cell-cell interactions, as well as gene and cell signaling activities. In addition to macrophages, they will examine bone cells, fibroblasts and epithelium, which are other cells that come into contact with implants.

Brunette says their findings could have wide application to other implants including hip joints, catheters and other devices that contact diverse tissues.

“Improved surfaces will enable faster integration of implants with bone or other tissues, as well as enable implants to be used in situations that currently have a high risk of failure.”

Brunette points out that under “more-or-less ideal” conditions, dental implant failure rates can be as low as one or two per cent. However, dental and other implants are now being employed in more challenging situations such as sites with poor bone quality.

“Failure rates can approach 30 per cent depending on risk factors that include smoking, oral hygiene, quality of bone and location within the mouth.”


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