Oxidative stress levels and oral bacterial milieu in the saliva from pregnant vs. non-pregnant women

Abstract

Background: Saliva plays a significant role in maintaining oral health and oral bacterial milieu. Difference in oxidative stress (OS) levels in saliva in conjunction with bacterial load between pregnant and non-pregnant women has not been studied previously. We hypothesized that the physiological changes in pregnancy alter oral bacterial milieu by promoting growth of Streptococcus mutans (SM) and Lactobacillus (LB), and increase OS in saliva. The aim of this study was to measure and compare the oral bacterial milieu, OS and total anti-oxidative capacity (TAC) in the saliva of pregnant and non-pregnant women. Method: In this cross-sectional study, we assessed oral bacterial milieu by culturing the SM and LB by using commercial kits, TAC by measuring 2, 2′-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid (ABTS) free radical scavenging activity spectrophotometrically and OS levels by measuring malondialdehyde (MDA) levels with commercial kits in the saliva of pregnant women (n = 38) at 18-20 weeks of gestation, who were compared with age-matching healthy non-pregnant women (n = 50). Results: Streptococcus mutans were found to be more abundant in the saliva of pregnant women compared with non-pregnant women (p = 0.003) but the difference was not significant for the LB (p = 0.267). TAC was found to be 46% lower in pregnant women's saliva compared to non-pregnant women [optical density (OD) measured at 731 nm as 0.118 ± 0.01 vs. 0.063 ± 0.02; p < 0.001]. OS, expressed as saliva MDA levels, was found to be 16% higher in pregnant women compared to non-pregnant women (1.07 nM MDA vs. 0.92 nM MDA; p = 0.023). Conclusion: Pregnancy has an adverse impact on oral bacterial milieu as demonstrated by increased colonization with Streptococcus mutans together with higher OS levels and decreased TAC levels in saliva. This emphasizes the importance of improved oral hygiene and provision of oral healthcare services during pregnancy care.

Nitric Oxide, Oxidative Stress and Streptococcus mutans and Lactobacillus Bacterial Loads in Saliva during the Different Stages of Pregnancy: A Longitudinal Study

“…For both pregnant and non-pregnant groups, saliva samples were collected during daytime between 9:00 and 15:00 h with the same method as described previously [10]. Women were not eating or brushing their teeth for approximately 1.0 to 1.5 h before sampling.…”

“…Antioxidant capacity (AC) in the saliva was assessed by measuring free radical scavenging activity by 2,2 -azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid diammonium salt (ABTS) methods with appropriate modifications [10,13]. In brief, ABTS free radicals (ABTS •+ ) having dark green color was generated by allowing the reaction equal volume (each 2 mL) of the solutions of ABTS (7.4 mM) and potassium peroxodisulfate (2.6 mM) for 24 h. The reaction mixture was diluted to 100 mL with distilled water as a working solution ABTS •+ .…”

“…We evaluated OS levels in saliva by measuring MDA content using a commercially available MDA Assay Kit (Sigma-Aldrich, Lipid Peroxidation MDA Assay Kit (MAK085), Darmstadt, Germany) [10]. In brief, a mixture of 100 µL saliva supernatant, 100 µL buffer provided in the kit, and 600 µL thiobarbituric acid (TBA) solution were mixed thoroughly and incubated at 95 • C for 60 min.…”

“…Oral bacterial culture was assessed by a single investigator (MW) by saliva culture and development of bacterial colony forming units (CFU) of two main bacteria, SM and LB, using commercial kits Dentocult ® LB (kit for LB), and Dentocult ® SM Strip mutans (kit for SM) (Orion Diagnostica Oy, Espoo, Finland) as described previously [10]. Women were requested to chew a paraffin pellet to stimulate the secretion of saliva and promote transfer of SM from tooth surfaces into the saliva.…”

“…A recent systematic review on maternal oral microflora has reported that the pregnancy is associated with abundance of micro-organisms compared to non-pregnant state [9]. In a cross-sectional study, we have previously demonstrated an increased level of OS in the saliva of pregnant women compared to non-pregnant in association with increased colonization of oral cavity by dental caries-related pathogen, Streptococcus mutans (SM) [10]. Increased levels of NO and OS have been measured in the blood samples of pregnant women compared to healthy non-pregnant women [6,11].…”