Investigating the Impact of Maternal Periodontitis on the Development of Mouse Placenta and Fetus

Abstract

Periodontitis is a chronic inflammatory disease characterised by infection and destruction of the tooth-supporting tissues, resulting in alveolar bone resorption and tooth loss. Beyond oral health, periodontitis is linked to systemic conditions such as cardiovascular disease, diabetes, and respiratory illness. Its association with adverse pregnancy outcomes (APOs) has also been proposed, albeit debatable. These discrepancies largely stem from varied study designs, differing diagnostic criteria, and difficulty isolating periodontitis as an independent risk factor from confounders. Periodontitis affects 40% of pregnant women, making it a potential major contributor to APOs. To better understand this potential relationship, robust prospective clinical studies are required. Well-designed animal models are also essential to uncover the mechanistic aspect of this relationship.

This thesis presents a novel mouse model of maternal periodontitis by ligating a maxillary molar to simulate calculus, and orally introducing a mix of human periodontal bacteria, favouring colonisation and survival of the keystone pathogen Porphyromonas gingivalis. The model was optimised to reduce induction time, minimising procedural burden while still inducing significant alveolar bone loss without impairing fertility. This enabled subsequent investigations into placental and fetal outcomes. The findings revealed that maternal periodontitis induces placental alterations that may reduce its efficiency in delivering oxygen, nutrients, and hormonal support to the fetus. These placental disruptions correlated with impaired fetal development and fetal demise, especially in offspring with mild genetic alterations that would not cause problems when conceived by healthy mothers.

This work strengthens the evidence linking maternal periodontitis to APOs, supporting the importance of integrating oral health into maternal care strategies to improve pregnancy outcomes.