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By Jennifer Garvin

Treatment for periodontal disease is safe for pregnant women, but such treatment does not reduce the risk of adverse outcomes, including preterm delivery, low birth weight, fetal growth restriction or preeclampsia.

Those findings are from a new study, "Treatment of Periodontal Disease and the Risk of Preterm Birth," published in the Nov. 2 issue of the New England Journal of Medicine .

Researchers based their findings on results from a four-site Obstetrics and Periodontal Therapy Trial that studied the effects of non-surgical periodontal treatment on preterm birth.

The National Institute of Dental and Craniofacial Research, which funded the OPT study, described it as the largest clinical trial to evaluate whether treating periodontal disease during pregnancy reduces a woman's risk of early delivery.

The study enrolled 823 women from Hennepin County Medical Center in Minneapolis, the University of Kentucky in Lexington, the University of Mississippi/Jackson Medical Mall in Jackson, Miss., and Harlem Hospital/Columbia University in New York.

The study defines "preterm delivery" as a birth that occurs before 37 weeks of pregnancy.

The women studied were between 13 and 17 weeks pregnant on entering the study, and all suffered from periodontal disease. Researchers separated the women into two groups: those who received root planing and scaling during pregnancy (before their 21st week), and a control group that received periodontal treatment after delivery.

The OPT data showed that 12 percent (49 of 407) in the treatment group delivered earlier than 37 weeks, compared to 12.8 percent (52 of 405) for the control group.

"This research does not show a direct cause and effect relationship between periodontal disease and preterm birth," said Dr. Bryan Michalowicz, the study's lead author and associate professor, Division of Periodontology, University of Minnesota School of Dentistry.

"A common, non-surgical treatment for periodontitis delivered between weeks 13 and 21 of pregnancy did not reduce the rate of preterm birth or low birth weight," added Dr. Michalowicz. "This could suggest that in the future, researchers [should] focus on testing other means to reduce rates of preterm birth."

For those dentists hesitant about treating pregnant patients, the study shows that treatment provided in the second or third trimester of pregnancy is safe. Women in the treatment group also received monthly prophylaxis.

"Dental care during pregnancy has long been an issue dominated by caution more than data," said Dr. Lawrence Tabak, NIDCR director, in the NIDCR press release. "The finding that periodontal treatment during pregnancy did not increase adverse events is important news for women, especially for those who will need to have their periodontal disease treated during pregnancy."

"As a dentist," Dr. Michalowicz said, "I am excited that our findings might be used to increase women's access to periodontal treatment, and that we confirmed the safety of periodontal care, which should help eliminate any negative perceptions about treating pregnant women . By demonstrating that treatment is safe and efficacious we hope these results go a long way in debunking those myths."

"That's good for everyone to know: pregnant women, OB/GYNs, dentists," said Dr. Kenneth Krebs, immediate past president, American Academy of Periodontology, adding that he also still believes there is a link between periodontitis and adverse pregnancy outcomes.

"I honestly do because you often see changes in the oral tissues during pregnancy," he said.

While the OPT study does not support a causal relationship between periodontal disease and preterm birth, an accompanying editorial in the NEJM written by Robert L. Goldberg, M.D., and Jennifer F. Culhane, Ph.D., maintains that future studies may show that periodontal treatment can help reduce other adverse outcomes including "late miscarriage, early stillbirth, and spontaneous preterm birth before 32 weeks, rather than all preterm births before 37 weeks."

"For those who believed there was no connection between periodontal disease and preterm birth, they'll look at this and say 'I told you so,'" said Dr. M. John Novak, a periodontist and one of two researchers who participated in the study from the University of Kentucky. "But for those who do believe that periodontal disease and negative obstetrical outcomes are somehow linked, this study does not provide the answer on how they are linked."

He added, "There are potentially a lot of environmental and behavioral factors to consider such as the impact of socioeconomic status, lifestyles and smoking, all of which are known risk factors for both periodontitis and preterm birth."

Dr. Daniel M. Meyer, associate executive director, ADA Division of Science, touched on pregnancy and periodontal disease in a recent special edition of Scientific American magazine. Genetic conditions and environmental issues, he said, must be weighed when considering systemic health outcomes.

"It is a well-designed study that provides valuable insight into the complexity of these relationships," Dr. Meyer said. "A single study often raises more questions rather than merely provide precise answers to some of our clinical questions. Oral-systemic relationships obviously exist. We will need to continue to explore the extent of these associations in order to gain a far better understanding on the relative risks, along with the most effective methods to improve health.

"The interactions of predisposing health conditions, whether oral or systemic, add to the complexities of determining the measurable health outcomes from a variety of current treatment options," Dr. Meyer added. "We need to continue to evaluate these relationships and in the meantime, not over interpret or misinterpret the significance of this study."

Another ongoing NIDCR-supported study, "Maternal Oral Therapy to Reduce Obstetric Risk," includes 1,800 women from a broader range of socioeconomic classes, as well as women with less severe periodontal disease. Results from that study are expected within the next two years, NIDCR reports.

"This first study has opened up the box a bit more and provides more questions than answers," said the University of Kentucky's Dr. Novak. "However, at the present time we are not yet able to say that periodontal therapy before or during pregnancy will impact preterm delivery."

He continued, "There are multiple studies going on at the moment, and we can't close the book on this intriguing question. We believe that an association exists. We just don't know what it is."

For more information on the OPT study, visit the NIDCR Web site . To read more from the ADA on the oral-systemic connection, visit www.ada.org/goto/oralsystemic.