Effects of ligature-induced periodontitis in pregnant Wistar rats

No association between periodontitis and preterm low birth weight: a case-control study

PURPOSE

This study aimed to investigate the association between periodontitis in pregnant women and adverse pregnancy outcomes by heeding confounding risk factors for preterm low birth weight infants.

METHODS

This study was reported according to The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement. A case-control study was conducted. Medical records of all pregnant women attending a prenatal care clinic were screened. Those between 21 and 34 years and gestational age of 28-32 weeks were initially enrolled in the study. The exclusion criteria were then applied: diabetes mellitus, genitourinary tract infections, or HIV infection; previous multiple gestations; previous preterm birth/low birth weight infants; in vitro fertilization procedures; placental, cervical/uterine abnormalities; history of infertility; history of drug abuse; and any medical conditions that required antibiotics prophylaxis. Patients' anthropometric, demographic, and behavioral characteristics were collected. The periodontal clinical parameters were obtained from six sites per tooth: clinical attachment level, probing pocket depth, dental plaque index, and gingival bleeding index. Women were then allocated into two groups: mothers of preterm and/or low birth weight newborns (cases) and mothers of full-term and normal birth weight newborns (controls).

RESULTS

Periodontal clinical parameters were analyzed and reported separately for each group, and no significant differences were observed (p > 0.05). Logistic regression analysis revealed that periodontal clinical parameters were not associated with the adverse pregnancy outcomes.

CONCLUSION(S)

After controlling for confounding factors, our results suggest that maternal periodontal disease is not a risk factor associated with preterm low birth weight infants.

No association between periodontitis, preterm birth, or intrauterine growth restriction: experimental study in Wistar rats

BACKGROUND

The biologic plausibility of the possible association between periodontitis and adverse pregnancy outcomes has been assessed with the use of different experimental models. However, most experimental studies did not induce periodontitis in the animals but promoted an acute microbial challenge with selected periodontal pathogens or their products subcutaneous or intravenous or intraamniotic. The present study was then conducted to verify the biologic plausibility of such association by experimentally inducing periodontitis in Wistar rats.

OBJECTIVE

An experimental study on an animal model by the induction of periodontitis in 50% of sites and assessment of the presence of cytokines in the gingival tissue, serum, placenta, cord, and amniotic fluid was designed to test the null hypothesis that experimental periodontitis that is induced on rats does not result in adverse pregnancy outcomes.

STUDY DESIGN

Forty female Wistar rats were included in 2 groups: a periodontally healthy (without ligatures) and an experimentally induced periodontitis group (test, with ligatures). Forty-five days after the induction, the mating was initiated. Males were placed with females in the ratio of 1:2 for a period of 12 hours. The bodyweight of the female, from then on, was recorded daily. When the pregnancy was confirmed on day 20, laparotomy was performed. The amniotic fluid, placenta, umbilical cord, blood (serum) and maternal and gingival tissue samples were subjected to quantitative analysis for interleukin 1α, -6, -10, -4, -12p70, and -17a, tumor necrosis factor-α, and interferon-γ by multiplex methods. Mean scores, standard deviations, and standard errors for estimated measures were calculated. For cytokines analyses, the Mann-Whitney test was conducted to compare the concentration of the analytes from control and test groups in the different tissues samples. For comparison of cytokines reduction from gingival tissue to serum and from serum to placenta, the Wilcoxon Test was performed. Spearman's correlation was conducted among cytokines in the 5 different tissues that were evaluated.

RESULTS

The induced periodontitis in Wistar rats did not result in adverse outcomes of pregnancy. There were no statistically significant differences between groups in relation to prematurity, fetal, or birth weight. Regarding cytokines, there were no statistically significant differences in concentrations that were measured in each tissue between the groups with periodontitis and controls. Furthermore, all cytokine levels in the placenta, except interleukin-6, were diminished compared with the amniotic fluid or maternal serum, which suggested that the cytokines cannot easily be transferred via this tissue in maternal-fetal or fetomaternal direction. The fertility rate was reduced significantly in the group with periodontitis.

CONCLUSION

Periodontitis that is induced in rats is not a risk factor for preterm birth or low birthweight.

The adaptive nature of the bone-periodontal ligament-cementum complex in a ligature-induced periodontitis rat model

The novel aspect of this study involves illustrating significant adaptation of a functionally loaded bone-PDL-cementum complex in a ligature-induced periodontitis rat model. Following 4, 8, and 15 days of ligation, proinflammatory cytokines (TNF-α and RANKL), a mineral resorption indicator (TRAP), and a cell migration and adhesion molecule for tissue regeneration (fibronectin) within the complex were localized and correlated with changes in PDL-space (functional space). At 4 days of ligation, the functional space of the distal complex was widened compared to controls and was positively correlated with an increased expression of TNF-α. At 8 and 15 days, the number of RANKL(+) cells decreased near the mesial alveolar bone crest (ABC) but increased at the distal ABC. TRAP(+) cells on both sides of the complex significantly increased at 8 days. A gradual change in fibronectin expression from the distal PDL-secondary cementum interfaces through precementum layers was observed when compared to increased and abrupt changes at the mesial PDL-cementum and PDL-bone interfaces in ligated and control groups. Based on our results, we hypothesize that compromised strain fields can be created in a diseased periodontium, which in response to prolonged function can significantly alter the original bone and apical cementum formations.

Periodontal status and preterm low birth weight: a case control study

BACKGROUND

Previous studies have suggested that periodontal disease may be an important risk factor for preterm low birth weight. However, the link between periodontal health status of pregnant women and preterm low birth weight is contentious, as recent studies found no association between periodontitis and pregnancy outcome.

OBJECTIVE

The aim of this study was to investigate this potential link in a German Caucasian population.

METHODS

Fifty-nine pregnant women with a high risk for a preterm low birth weight infant (suffering from preterm contractions, cases, group 1) as well as 42 control women with no preterm contractions during pregnancy and having an infant appropriate for date and weight (>or= 37 weeks gestation, >or= 2500 g, group 2) were examined. Clinical periodontal status was recorded on a full mouth basis. Subgingival plaque samples were taken and periodontal pathogens were identified by polymerase chain reaction. Additionally, interleukin-1 beta level in gingival crevicular fluid was analysed.

RESULTS

The mean percentage of sites showing moderate to advanced attachment loss (>or=3 mm) was low in all study groups (group 1: 9.9 +/- 11.2%; group 2:10.6 +/- 14.1%, respectively). No significant differences between the groups in any aspects of the studied periodontitis parameters could be detected. Using a logistic regression model controlling for known preterm low birth weight risk factors, no periodontitis-associated factors increased risk for preterm contractions or preterm low birth weight. The odds ratio (OR) was 1.19 for preterm contractions, the 95% confidence interval (CI) 0.46; 3.11 and 0.73 for preterm low birth weight; 95% CI: 0.13; 4.19, respectively.

CONCLUSION

In this population, periodontitis was not a detectable risk factor for preterm low birth weight in pregnant women.