|Study Finds Periodontal Treatment Does Not Lower
Preterm Birth Risk
Scientists supported by the National Institute of Dental and Craniofacial
Research, part of the National Institutes of Health, report in
this week’s New England Journal of Medicine that pregnant
women who received non-surgical treatment for their periodontal,
or gum, disease did not also significantly lower their risk of
delivering a premature or low-birthweight baby.
These results come from the largest clinical trial to date to
evaluate whether treating periodontal disease during pregnancy
reduces a women’s risk of early delivery, an idea that has emerged
as a possibility in recent years. Non-surgical, or standard, periodontal
treatment involves thoroughly cleaning the teeth above and below
the gums, commonly called scaling and root planing.
The study, called the Obstetrics and Periodontal Therapy Trial
(OPT), also evaluated the safety of general dental care during
pregnancy. It found that dental treatment through the second trimester — both
general and periodontal care — did not increase the number
of adverse events for women during pregnancy.
Until now, little research had been conducted on the subject,
although dentists generally provide limited dental care to women
only during the second trimester when the fetus has reached a more
stable developmental stage and before treatment becomes too physically
cumbersome for the mother.
“Dental care during pregnancy has long been an issue dominated
by caution more than data,” said NIDCR director Dr. Larry Tabak. “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
In the United States, more than one-half million — or about
one in eight — babies are born prematurely, which is defined
as a birth that occurs before 37 weeks of pregnancy. Extremely
preterm babies can be so small and underdeveloped that they must
remain hospitalized for months, and, if they survive, spend years
battling chronic health problems.
This has spurred scientists to identify several risk factors associated
with premature births. These include smoking, low-income status,
hypertension, diabetes, alcohol use, and genitourinary tract infections.
However, the list remains incomplete. As many as half of all preterm
births occur without any clear explanation, and that has left scientists
searching for additional susceptibility factors to help more mothers
and ultimately reduce the estimated $26.2 billion annual cost to
the nation for preterm births.
Over the last two decades, scientists have generated data in observational
studies that suggest periodontal disease during pregnancy might
be one of those elusive risk factors. The theory is based on the
idea that bacteria associated with periodontal disease may spread
to the womb and help to induce preterm births. Results of a previous
small-scale clinical trial further supported this idea, but what’s
been missing are more definitive data from larger, randomized clinical
To fill this public-health need, the NIDCR funded two large, randomized
clinical trials. The first to publish its results is the OPT, which
included four participating centers: Hennepin County Medical Center
in Minneapolis, University of Kentucky in Lexington, University
of Mississippi/Jackson Medical Mall in Jackson, Miss., and Harlem
Hospital/Columbia University in New York City.
Launched in March 2003, OPT enrolled a total of 823 women with
periodontal disease, all of whom were between 13 and 17 weeks pregnant
upon entry into the study. Each woman was randomly assigned to
receive either: (1) scaling and root planing of the teeth prior
to the 21st week of pregnancy, then monthly tooth polishings or
(2) scaling and root planing after delivery, meaning women in this
group did not have their periodontal disease treated during their
pregnancies. All women were 16 years or older to participate, and
basic dental care was provided to everyone in the study.
According to Dr. Bryan Michalowicz, a periodontist at the University
of Minnesota and the lead author of the study, one of the OPT’s
strengths is its four regional centers generally provide prenatal
care to low income, underserved women of all races, who are recognized
as being at particularly high risk for early delivery.
“When trying to define risk factors for preterm birth, it’s difficult
to control for characteristics that may differ between full and
preterm mothers, such as socioeconomic status or access to health
and dental care,” said Michalowicz. “By randomly assigning women
from the same high-risk populations to receive treatment either
before or after delivery, we could minimize such differences between
As reported this week, the OPT data show:
- Birth Outcomes: Forty nine (12.0 percent)
women in the treatment group had pregnancies ending before 37
weeks compared to 52 (12.8 percent) of those in the control,
or delayed treatment group. Nineteen miscarriages occurred, although
the numbers were not indicative of a statistically significant
trend in either group. These included: Six spontaneous abortions
(two in the treatment group, four in the control group) and 13
stillbirths (three in the treatment arm, 10 in the control group.
A spontaneous abortion was defined as a loss of the baby before
20 weeks, while a stillbirth was considered to occur from 20
weeks to 36 weeks and six days. The researchers also found no
significant differences among the two groups in the proportion
of infants who were of low birthweight, defined as weighing less
than 2500 grams, or about five and half pounds.
- Periodontal Disease: Most women had early
to moderate periodontal disease. The researchers found that the
treatment improved all clinical measures of periodontal disease.
These included the bleeding of gums when probed, the probing
depth between the tooth and gum, and measuring tooth attachment.
As additional evidence, the researchers found no difference in
risk for preterm birth when they compared treatment and control
women who had the most extensive bleeding of the gums, a sign
of inflammation, or more advanced periodontal disease at entry.
They also found no differences when they examined a subset of
women in the treatment group whose periodontal disease had improved
the most during the study.
- Safety of Periodontal Therapy: Women in both
groups had similar rates of adverse medical events, such as hospitalization
of more than 24 hours for labor pains. This is an indication
that periodontal therapy had no obvious effect on pregnancy.
“This study highlights the power of merging disciplines, in this
case dentistry and obstetrics, to pursue a public-health question,” said
Dr. Virginia Lupo, an author on the study and an obstetrician at
the Hennepin County Medical Center in Minneapolis. “We literally
set up dental practices within our obstetrics clinics, and that
was a very unique and needed approach.”
Although OPT is now the largest study to publish on the subject,
the NIDCR-supported Maternal Oral Therapy to Reduce Obstetric Risk
(MOTOR) study is ongoing. “It’s just good science to conduct more
than one large clinical trial on any public health question,” said
Dr. Jane Atkinson, program director of NIDCR’s Clinical Trials
Program. “If periodontal disease plays any role in preterm birth,
we want to cast a wide enough investigational net to determine
which women are at risk.”
Atkinson said the 1,800-patient MOTOR study is designed a little
differently than OPT. It involves a broader socio-economic cross
section of women, provides fewer basic dental services, and includes
women with slightly less severe periodontal disease. MOTOR will
likely report its results within the next two years.
The article is titled “Treatment of Periodontal Disease and The
Risk of Preterm Birth” and appears in the November 2, 2006 issue
of the New England Journal of Medicine. The authors are:
Bryan S. Michalowicz, James S. Hodges, Anthony J. DiAngelis, Virginia
R. Lupo, M. John Novak, James E. Ferguson, William Buchanan, James
Bofill, Panos N. Papapanou, Dennis A. Mitchell, Stephen Matseoane,
and Pat A. Tschida.
The National Institute of Dental and Craniofacial Research
is the nation’s leading funder of research on oral, dental, and
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