1. To generate alveolar bone loss and periodontal inflammation consistent with periodontitis in mice, using Fusobacterium nucleatum and Porphyromonas gingivalis;)
2. To determine whether F. nucleatum is capable of translocating from the periodontium to the murine placenta haematogenously;
3. To determine whether experimentally induced periodontitis with F. nucleatum and P. gingivalis increases adverse birth outcomes in mice.
Periodontitis was induced in mice using a mixture of F. nucleatum and P. gingivalis, suspended in 2% carboxymethyl cellulose brushed into the gingival sulcus over 40 days. Mice were mated and bacterial inocluations continued until day 18 of gestation. The mice were euthanased and the placenta, liver, spleen and blood extracted and assessed for the presence of F. nucleatum and P. gingivalis by polymerase chain reaction (PCR) (16srRNA).
The maxillary and mandibular buccal gingivae and oral mucosa were harvested by sharp dissection. Half of each head was defleshed mechanically using 1% sodium hydroxide solution (NaOH) and assessed for bone loss (increased distance between the buccal cemento-enamel junction and alveolar bone crest) using a Leica MZ16FA stereomicroscope compared to controls. The other half was fixed in 10% formalin and histologically assessed for periodontal inflammation.
Alveolar bone loss was evident in the buccal maxilla and mandible in five of ten experimental mice compared to controls. Pregnancy rates were low at 50%. Adverse pregnancy outcomes were evident in one experimental mouse (2 pups carried only compared to 7-10 pups in control mice.) PCR analysis is ongoing.
Experimentally induced periodontitis with F. nucleatum and P. gingivalis in mice may cause adverse pregnancy outcomes via the haematogenous translocation of bacteria and feto-placental infection. More information is needed to determine the exact link between periodontitis and pregnancy outcomes. Oral inoculation of F. nucleatum and P. gingivalis in mice is an effective animal-based model of periodontitis.