Oral health in pregnancy: changes in oral bacterial milieu related to cariogenic bacterial load, oxidative stress and nitric oxide levels in the saliva and their effect on pregnancy outcome

Abstract

The physiological changes that occur during the pregnancy are known to affect women´s oral health. Pregnant women are more vulnerable to oral diseases when compared to non-pregnant. Better understanding of the relation between changing oral microbial milieu and risk of pregnancy complications and associated mechanisms could help to improve maternal and perinatal outcomes. Thus, we aimed to investigate the pregnancy associated changes in oral bacterial milieu with a focus on cariogenic bacterial load, oxidative stress and nitric oxide levels in the saliva, and their effect on pregnancy outcome. The study included a total of 146 participants, 96 healthy pregnant women at 18-20 weeks of gestation and 50 age-matched non-pregnant women for comparison. Saliva samples were collected from both groups under similar situation for investigating oral bacterial load of Streptococcus mutans (SM) and Lactobacillus (LB), and for determining salivary antioxidant capacity, oxidative stress (OS) and nitric oxide (NO) levels. We found an increase in salivary OS and a decrease in antioxidant capacity along with an increase in colonization by SM in pregnant women compared to non-pregnant. The salivary NO levels were also higher among the pregnant women compared to non-pregnant and the NO level increased with advancing gestational age. However, an association between dental caries and risk of preterm birth was not observed based on data obtained from the published literature. In conclusion, pregnant women had increased load of caries related bacteria, especially SM, in the saliva with higher OS levels and decreased antioxidant capacity compared to non-pregnant women. Likewise, there was an increase in salivary NO levels with advancing gestational age, and an increase in bacterial colonization by SM and LB among the pregnant women in their second and third trimesters. No significant association was observed between dental caries and increased risk of preterm birth.