Bill Costerton

In the battle against periodontal disease, there are two fronts.

The well-equipped microscopists take aim at the oral cavity through the steady lens of their high-intensity microscopes.

The microbiologists, on the other hand, are in the trenches (of the gums) analyzing the microbial makeup of the bacteria that cause gingival infections like periodontitis.

A new tool currently under construction at the USC Health Sciences Campus will help build a united offense against the disease. A two-photon confocal (or “capture”) microscope will be the sixth of its kind in the world and will give USC School of Dentistry (USCSD) researchers a unique look at the bacteria potentially responsible for gum disease.

As Bill Costerton, director of USC’s Center for Biofilms, explained, the capture microscope magnifies the bacteria taken from a patient with periodontal disease, while a special laser attachment can cut out and remove a minute sample from that population. An attached collector then analyzes the sample’s DNA structure.

“This is a high-end research tool and an amazing bit of technology,” Costerton said from his office in the Norris Dental Science Center. “That you can actually look under a microscope, find an interesting bunch of cells, ask yourself, ‘Say, they’re wreaking a lot of havoc. I wonder what those are?’ And then zoop, you can pop them right out and do an analysis. This is a real breakthrough.”

The microscope will be a critical tool in the Center for Biofilm’s grant-funded study of periodontal disease. With funding from Philips Oral Healthcare, Inc., the Center is assigned the task of studying the molecular makeup of bacteria living within the periodontium. But traditional microscopic and microbiological methods just weren’t cutting it, Costerton said.

Morphologists see the bacteria in action through a microscope but cannot identify unknown pathogens. Molecular biologists can analyze the RNA of unidentified bacteria, but cannot observe the role a bacterium plays in gum disease.

“What you have are two different camps here. You’ve got the microscope people who can look at what’s happening and the molecular people who can analyze what’s happening,” Costerton said.

This microscope will bridge the two techniques, he said, providing both finer microscopy as well as the ability to generate genetic information from it.

“The two camps are improving their understanding of the same disease separately, but when they make the magic connection, that is where the action is. Where they connect and what we learn from that collaboration, that will be very important,” he said.

The microscope typically goes for $1.2 million, but USC is providing the funds to refurbish an existing microscope with these added features provided by the German-based optics manufacturer Carl Zeiss, Inc., at a substantially lower cost.

With an estimated 400 types of bacteria living inside the oral cavity, and roughly 40 really understood, Costerton and his team have their work cut out for them. More than half of the bacteria the research project has found so far have not been previously identified.

“Periodontitis doesn’t have a single causative organism. It is instead caused by a mixed bag of bugs,” Costerton said. “The problem is, we don’t know all the members of the mixed bag yet.”

His research hopes to identify the particularly pathogenic bugs causing gum disease. Once the bacteria are identified, antibiotics can be tailored to attack the inflammation.

“The bacteria are all hunkered down in biofilms and perhaps we haven’t identified the ones really responsible yet. Or maybe there’s a fungus involved,” he said. “You’ve got to understand what’s there before you can properly treat it.”

The capture microscope will be an instrument jointly shared by USCSD, the Viterbi School of Engineering and USC’s Doheny Eye Institute at the Keck School of Medicine. The microscope will be fully operational, Costerton expects, by the end of the summer.