Porphyromonas species are frequently isolated from the oral cavity and are associated with periodontal disease in both animals and humans. Black, pigmented Porphyromonas spp. isolated from the gingival margins of selected wild and captive Australian marsupials with varying degrees of periodontal disease (brushtail possums, koalas and macropods) were compared phylogenetically to Porphyromonas strains from non-marsupials (bear, wolf, coyote, cats and dogs) and Porphyromonas gingivalis strains from humans using 16S rRNA gene sequence analysis. The results of the phylogenetic analysis identified three distinct groups of strains. A monophyletic P. gingivalis group (Group 1) contained only strains isolated from humans and a Porphyromonas gulae group (Group 2) was divided into three distinct subclades, each containing both marsupial and non-marsupial strains. Group 3, which contained only marsupial strains, including all six strains isolated from captive koalas, was genetically distinct from P. gulae and may constitute a new Porphyromonas species.

The koala is one of Australia's most highly specialized folivores with a diet exclusively of eucalyptus leaves to provide all nutritive needs and therefore requires to be free of oral disease as they are dependent on good dentition for optimal health and quality of life. We developed an oral examination methodology based on protocols for companion animals and human dentistry to chart the oral health of koalas. Thirty free-ranging koalas from South-East Queensland, Australia were examined for general body and oral health. Inspection of the oral cavity was conducted for the presence or absence of the indicators oforal disease such as caries or periodontal disease. Univariate and multivariate analyses were performed on the examination data and a prototype oral health chart developed. The prototype was then trialled and the methodology validated by the Kappa statistic using ten additional koalas examined by four multidisciplinary personnel involved in koala care. Trauma associated fractures, tooth displacement, abnormal occlusion and tooth wear compacted vegetation, extrinsic stain deposits, periodontal bone loss, gingivitis, tooth mobility, and calculus were present in the oral cavities of the examined koalas. A system of scoring between 0 and 3 was constructed in accordance with current koala general health charting formats. Validation of the charting method using Kappa coefficients of agreement statistics indicated that there was a good agreement among observers on recorded results except for inflammation and calculus scoring. Modifications were made and visual aids and index scales produced to further assist observers. Oral health surveillance has been proven in other species to be significant in diagnosing physiological disturbances derived from environmental genetic, and developmental causes. Veterinarians, dental researchers, and koala husbandry personnel will benefit in using this charting method and reporting the oral health of koala populations in their future findings. This unique form of oral health monitoring would be adaptable to other mammals.

This study investigated changes in alveolar bone height in free-ranging koalas of different age groups. Twenty-seven free-ranging Queensland koalas (15 female, 12 male), admitted to the Moggill Koala Hospital, Brisbane, were used in this study. Koalas were divided into three groups (young, adult, old) on the basis of tooth wear, each group containing nine animals. Defleshed jaws were examined for the presence of alveolar bone defects. The distance from the cemento-enamel junction and the interproximal crestal alveolar bone height was measured on the buccal aspects of the second and third molars. Jaws were photographed and radiographed. Bone defects (dehiscences and fenestrations) were observed in both jaws and were predominantly located on the buccal aspect of the alveolar process. The loss of height of crestal alveolar bone, relative to the cemento-enamel junction, increased with age, with 25 koalas showing moderate to severe bone loss and only two koalas having none/mild loss levels at all measurement sites. Female koalas had higher frequency of ‘none/mild’ cases of bone loss than did males. There was no variation in levels of alveolar bone loss between the upper and lower jaws or the corresponding right and left arches.

Background In northern Australian koala populations (Queensland and New South Wales), periodontal disease (gingivitis and periodontitis) is common while koala retrovirus subtype A is endogenous, with other subtypes transmitted exogenously. Koala retrovirus has been hypothesised to cause immune suppression and may predispose koalas to diseases caused by concurrent infections. In southern Australia populations (Victoria and South Australia) periodontal disease has not been investigated, and koala retrovirus is presumably exogenously transmitted. This study described oral health in South Australian koalas and investigated if an association between periodontal disease and koala retrovirus exists. Methods Oral health was examined for wild‐caught koalas from the Mount Lofty Ranges (n = 75). Koala retrovirus provirus was detected in whole blood using nested PCR and proviral load determined with qPCR. Periodontal disease severity was recorded and used to calculate the Final Oral Health Index (0‐normal, 24‐severe).Results Periodontal disease was observed in 84% (63/75) of koalas; 77% had gingivitis (58/75) and 65% (49/75) had periodontitis. The average Final Oral Health Index was 5.47 (s.d 3.13). Most cases of periodontal disease were associated with the incisors. Koala retrovirus‐infected koalas were more likely to present with periodontitis (p = 0.042) and the Final Oral Health Index was negatively correlated with proviral load (ρ = −0.353, p = 0.017). Conclusion South Australian koalas had a high prevalence of gingivitis and periodontitis. Periodontal disease was more prevalent in the incisors. Exogenous koala retrovirus infection may also facilitate the development of periodontitis by modulation of the immune response to concurrent oral bacterial infections.