Endo vs. implant battle heats up

2009 02 04 15 53 11 946 Boxing Glove 70

Why waste time on heroic root canal therapy that's doomed to fail? Why waste money on an implant if you can save a natural tooth?

As implant specialists and endodontists have improved their techniques the past few years, the battle between them has intensified. In recent months, endodontists have produced a couple of studies comparing implants to endodonics, one in November showing that endodontic teeth need less maintenance and another in January showing that endodontic teeth can chew better than implants.

In a November 13 press release, the American Association of Endodontists (AAE) warned that placing an implant "can take three or more visits over the course of several months to complete and can be time-intensive and costly."

Why the PR effort?

"I think people are fearful sometimes to have an endodontic procedure performed," AAE President Louis Rossman, D.M.D., told DrBicuspid.com. "We want people to know that you often can save your natural tooth through a virtually painless root canal procedure that has an extraordinary success rate of 98%."

That argument gets under the skin of Ken Judy, D.D.S., Ph.D., the co-chair of the International Congress of Oral Implantologists and a clinical professor of oral implantology at New York University.

"They are literally scaring people away from implants to affirm their specialty," he said. "Endodontists are used to getting people out of pain. They don't look at the long-term survival."

Indeed, the most recent studies are fairly short-term.

The occasion for the AAE press release was a study published in the Journal of Endodontics that found that implants require more follow-up interventions (JOE, November 2008, Vol. 34:11, pp. 1302-1305). The difference was statistically significant -- 12.4% of 129 implants needed intervention, compared to only 1.3% of 143 endodontically treated teeth (p = 0.0003).

But the study was retrospective; the researchers, from the endodontics department at the University of Alabama at Birmingham School of Dentistry, analyzed patients' charts rather than randomly assigning teeth to one type of treatment or the other. Also, they compared the success rate of implants over an average of 36 months but endodontically treated teeth for only 22 months.

Then in January, the same journal published a study looking at the problem from the perspective of chewing (JOE, January 2009, Vol. 35:1, pp 10-14). This time endodontists from the Baylor College of Dentistry measured how well the teeth actually worked in 25 patients with endodontically treated mandibular molars and 25 patients with implants in the mandibular molar region. In each patient, the researchers compared the treated tooth to an untreated tooth on the opposite side of the mouth.

First, they tested the force with which the patients could bite down, using a force transducer. Patients bit down just as hard with their endodontic teeth as with the healthy teeth on the other side of their mouth. But patients with implants bit down with much less force (p = 0.015).

Next, the researchers asked the patients to chew CutterSil (Heraeus Kulzer) artificial food on one side of the mouth and spit it out into a paper filter. They repeated the experiment on the other side of the mouth. Then they measured the size of the chewed particles using a sieve. Here, too, they found no difference between the endodontic teeth and the healthy teeth, but did find a statistically significant difference (p = 0.050) between the implant teeth and the healthy ones. The implant teeth didn't grind the food up as thoroughly.

After that, the researchers measured the occlusal contact area of the patients by taking an impression, scanning it, and measuring the pixels on a grayscale. The occlusal contact area of the endodontic teeth was statistically similar to that of the healthy teeth, but the contact area of the implant teeth was on average 38.5% smaller, a statistically significant difference (p = 0.001).

Finally, they asked the patients whether they noticed any difference between the restorations and the healthy teeth. There was no significant difference.

Their conclusion? "You can chew better with an endodontically treated tooth," said Jianing He, D.M.D., Ph.D., an assistant professor of endodontics at Baylor. "If you can chew better, you can break down food better and digest better, so we believe it has implications for health."

Case closed?

Asked why patients with implants were just as happy as patients with endodontically treated teeth, Dr. He said the questionnaire used to measure their satisfaction may not have been sensitive enough to pick up the difference.

She said implants may not chew as well because they are typically set slightly out of occlusion. Since they are set in bone, they might otherwise put too much force on opposing teeth.

Dr. He also noted that endodontic teeth retain periodontal ligaments that allow them to move slightly and allow the patient to feel the force on their teeth so they can better calibrate their chewing.

But this study proves nothing, Dr. Judy said. "Doing a research project on such a question is absolute nonsense," he said. "It's a hypothetical question that ignores the mechanics of each individual case."

In the first place, patients in real life don't chew on one side of their mouths, then the other; they chew with all the teeth they can. "A single tooth seldom makes a difference in how well a patient can chew," he said.

There are also many more important factors that dictate which type of treatment a tooth should get, such as how much bone the patient has, what is opposing the tooth in question, and the condition of the adjacent teeth.

On this central point, at least, Dr. Rossman agreed. "I think implants are wonderful," he said. He would just like patients to first make every effort to save the natural tooth by consulting an endodontist.

Copyright © 2009 DrBicuspid.com

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