AbstractTwenty‐seven proprietory periodontal dressings were applied to the lower labial segments of 18 subjects showing low levels of gingival inflammation when assessed by the Gingival Index system at the time of application. Specimens of each dressing type were subsequently removed at intervals ranging from 3 h to 5 days. The material adhering to the deep surface of the dressing was examined by light, transmission and scanning electron microscopy and was shown to be a complex heterogeneous structure consisting of large intact epithelial cell sheets and oral bacteria in a proteinaceous matrix. Possible mechanisms which could contribute the epithelial cell and protein components to this structure were discussed. It was concluded that the dressings themselves caused little damage to the normal periodontium but could be associated with increased levels of inflammation at longer time intervals because of bacterial growth. The significance of these findings to current clinical practice is discusse