INTELIHEALTH - Dental treatment, including the use of local anesthetics, appears to be safe between the 13th and 21st weeks of pregnancy.

Researchers did a study that used information from the Obstetrics and Periodontal Therapy Trial. This trial included more than 800 pregnant women. All were at high risk of preterm birth, and all had periodontal disease.

The women were randomly assigned to get treatment between the 13th and 21st weeks of pregnancy, or three months after giving birth. In 2006, the trial found that getting periodontal treatment during pregnancy did not increase the risk for preterm birth.

The women also received dental exams. They were told if they needed cavities filled, teeth pulled or root canal therapy. About 350 women needed at least one of these treatments.

This created four groups of women:

• Those who got both periodontal treatment and other dental treatment during pregnancy
• Those who got periodontal treatment during pregnancy, but not other dental treatment
• Those who got periodontal treatment after pregnancy, and dental treatment during pregnancy
• Those who got periodontal treatment after pregnancy, and did not need other dental treatment

The researchers found no risk for getting dental treatment during pregnancy. Compared with women who did not need dental treatment, women treated during pregnancy were not more likely to:

• Have a miscarriage or stillbirth
• Give birth prematurely
• Have a fetus with an abnormality

Among the women who got fillings, root canals or extractions, it didn't matter when they had periodontal treatment -- during or after pregnancy.

Some of the women who got periodontal treatment received a numbing shot, gel or cream. These women also were not more likely to have birth-related problems.

On average, a woman who needed dental treatment made two office visits to get it. Some women had as many as 10 teeth extracted and visited the dentist as many as 9 times.

The researchers concluded that pregnant women can safely get needed dental treatment between the 13th and 21st weeks of pregnancy. This includes the use of a numbing shot, gel or cream.

Experts suggest avoiding unnecessary dental treatment during the first trimester. This is when fetal organs are forming. They also suggest avoiding it during the last several weeks of pregnancy. During this time, sitting in the dental chair can be uncomfortable and restrict blood flow.

Treatment during the second trimester is usually regarded as safe, but few studies have been done in this area.

More than 6 million women become pregnant every year in the United States. Most of them don't visit a dentist at all. The authors of this study suggest that both pregnant women and dentists may be responsible for this avoidance of dental treatment during pregnancy. Pregnant women may keep away the dentist out of fear, but dentists also may avoid treating pregnant women.

An earlier survey reported that only about 10% of dentists said they would do all of the necessary dental treatment that a pregnant woman might need. Also, 14% of dentists did not want to use numbing shots in pregnant women.

The pregnant women who were observed in this study were mostly black or Hispanic, and were at high risk for preterm birth. It is possible that the reported findings would not be the same for women at low risk for preterm birth or for other races and ethnic groups.

The researchers did not collect information about the types of dental fillings that the women received. It is possible that some materials, such as silver amalgam (which contains mercury), may cause problems in pregnancy. This is an area that requires further research and observation.

The study appears in the June issue of the Journal of the American Dental Association.