SUBGINGIVAL MICROBIOTA OF SHALLOW PERIODONTAL POCKETS IN INDIVIDUALS AFTER HEAD AND NECK IRRADIATION

This study aimed at investigating the subgingival plaque microorganism s of shallow pockets (less than or equal to 5 mm) in subjects who prev iously received irradiation in the head and neck region for treatment of nasopharyngeal carcinoma. Direct microscopy and anaerobic culture w ere used. Subgingival paper point samples were taken from 6 tooth-site s (one/sextant) per subject for direct microscopy (n=108). Another set of paper points was taken from the deepest of the previously selected sites (one per subject) with: group A) no bleeding on probing to the sulcus depth (n=9) and group B) bleeding on probing to the sulcus dept h (n=6) for microscopic and anaerobic culture study. Under the microsc ope, the microflora was found to be a complex mixture comprising gram- positive and gram-negative cocci, rods and filaments, fusiforms, curve d rods and spirochetes. Low level of fungi were observed and mycelia w ere occasionally detected. There was no significant variation in the p laque bacterial morphotypes observable according to sites of isolation and no significant difference between group A and group B in morphoty pes of the different microflora. The predominant cultivable microflora comprised several species of facultative and obligate anaerobic bacte ria: Gemella, Peptostreptococcus, Staphylococus, Stomatococcus, Strept ococcus, Actinomyces, Eubacterium, Lactobacillus, Propionibacterium, N eisseria, Veillonella, Bacteroides, Campylobacter, Capnocytophaga, Fus obacterium, Kingella, Porphyromonas and Prevotella species. There was no difference between the two groups except the significantly higher p roportion of Kingella dentrificans isolated from group B sites. Howeve r, colonization of the gingival sulcus in these individuals by microbe s that are normal flora of: skin (Peptostreptococcus prevotii and Prop ionibacterium granulosum) and gut (Eubacterium aerofaciens, Fusobacter ium mortiferum and Fusobacterium varium) was detected. These findings appear to suggest that the major components of the subgingival microfl ora of shallow sites in previously head- and neck-irradiated individua ls are similar to that of gingivitis sites in the normal population al though they may contain bacterial or fungal species uncommon in normal subjects.