Factors influencing oral health in patients during cancer treatment; with emphasis on the relationship between the oral microbiome and oral mucositis

The consequences of cancer therapy for oral health were studied. The effects of irradiation to the head and neck area for the protein composition of parotid saliva were mapped. It was found that irradiation to the head and neck area likely altered the gland tissues resulting in a change in the protein composition of parotid saliva. Furthermore, the role of the oral microflora in the course of oral mucositis and systemic complications after hematopoietic stem cell transplant (HSCT) were studied. Inflammation of the periodontium may be a risk factor for developing systemic infectious complications. Oral microorganisms are related to oral infectious complications since the microorganisms; the virus HSV-1, bacterial species that are associated with periodontitis P. gingivalis, P. micra, T. denticola and F. nucleatum and the yeasts C. glabrata and C. kefyr were positively associated with the presence of oral ulcerations in patients after HSCT. Some of these bacteria may prolong the existence of oral mucositis as they were able to hinder closure of a wound in oral epithelial cells in vitro. P. gingivalis was the most potent inhibitor of wound healing. From the known virulence factors that P. gingivalis possessed, the capsular polysaccharide and the gingipains influenced the capacity of P. gingivalis to hinder wound healing. Although microorganisms were considered to have only a minor role in oral mucositis, this thesis shows that they can influence the course of oral mucositis at least by inhibiting the healing of lesions.