Background: Entamoeba gingivalis was the first commensal parasite detected in the oral cavity of humans, and a high incidence has been reported in patients with poor oral hygiene. The current study aimed to investigate the association of Entamoeba gingivalis with gingivitis and periodontitis among Egyptian subjects. Methods: A total of 120 plaque samples were collected for this case-control study and were divided as follows: 40 plaque samples from gingivitis patients (group 1), 40 from stage II grade A and B periodontitis patients (group 2), and 40 samples from healthy volunteers (group 3). Diagnosis of parasitic stages relied on direct microscopic detection using permanent stains, trichrome stain, and hematoxylin and eosin (H&E) stain, in addition to ocular micrometry to confirm the diagnosis. Results: The occurrence of Entamoeba gingivalis within the gingivitis group was significantly higher (40%) than that observed in the control group (22.5%), whereas the occurrence within the periodontitis group was 15%. Samples from diseased subjects, regardless of immune status, were found to be moderately to severely affected with numerous parasitic nests, in contrast to a moderate near mild occurrence that was recorded in the healthy control group. Moreover, Entamoeba gingivalis occurrence was significantly higher (77.4%) in subjects with bad oral hygiene. Conclusion: The results of the present study suggest a potential role for the neglected oral parasitic Entamoeba gingivalis, especially the intensively multiplying forms, in the pathogenesis of periodontal diseases. This certainly needs further elucidation on a larger scale to explore the basis behind such multiplication, which may be related to genetic variation or may be pathophysiological in origin.

Background: Regulation of the plasminogen activation system (PAS) is a vital component in governing proteolytic events within the extracellular matrix (ECM). PAS is believed to play a substantial role in the destruction and healing of periodontal tissues. Thus, the current work aimed to study the histopathological effect of open flap debridement (OFD) on periodontitis, as well as its effect on tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) gene levels in gingival tissues. Methods: A total of 30 subjects were enrolled in the present study. They were divided into two groups: Group I (control group) included 10 periodontally healthy volunteers and group II (periodontitis group) comprised 20 patients suffering from stage III grade B periodontitis. Gingival tissue samples were collected from all periodontitis patients, before and after OFD, and from healthy controls. Hematoxylin and eosin (H&E) stained slides were subsequently examined and gene expression levels of t-PA and PAI-1 were assessed in the gingiva through quantitative reverse transcription polymerase chain reaction (RT-PCR). Results: Gingival tissue samples from periodontitis patients showed widely dilated blood vessels, diffuse hemorrhage, areas of edema, and disorganized collagen fibers together with large amounts of inflammatory cells in between. Following OFD, smaller sized blood vessels, a restored collagen fiber distribution, and an obvious decrease in the inflammatory infiltrate were noted. Gene expression levels of t-PA and PAI-1 were significantly higher in the periodontitis patients compared to the healthy controls. Although their levels showed a significant decrease following OFD in the periodontitis group, they were still significantly higher than the control group. Conclusion: OFD procedures resulted in down regulation of t-PA and PAI-1 expression levels in the gingiva of periodontitis patients, which could signify an important role of these proteins on periodontal disease progression.