In this study we looked into the incidence of
Entamoeba gingivalis in periodontal disease. The following factors are connected to the significance of this work: A substantial risk to the public’s health is posed by the high incidence of periodontal disease (gingivitis and periodontitis) among people of all ages, which can lead to tooth loss [
30,
31,
32,
33]. Some key factors of periodontitis have not been identified yet [
4]. In the aetiology of periodontal diseases, the bacterial factor has been described numerous times [
4,
34,
35]. On the other hand, parasites have not been investigated throughout. With the new advancement in the scientific world that proved that
Entamoeba gingivalis is causing tissue damage, [
9] our study aimed to evaluate the prevalence of these species in correlation with periodontal tissues. The prevalence reported in the case-control groups which were not diagnosed with oral disease was 18%, lower than in the periodontal disease group. These results are similar to those reported by other authors like Badri et al. [
36], X. Bao et al. [
9] which showed that the prevalence of
Entamoeba gingivalis was also significantly higher in periodontal disease cases compared to the case-control study group. The increased prevalence in some of the case-control group can result from different methods used or smaller sample sizes. Interestingly, studies that showed a higher prevalence in the case-control group used the direct method. When comparing periodontal diseases namely, gingivitis which is characterized by no attachment loss versus periodontitis which has a certain degree of attachment loss, the results showed that the prevalence of
Entamoeba gingivalis in patients with gingivitis was higher than in patient with periodontitis. This is contrary to other authors that described that the prevalence increases in periodontal disease severity [
29,
36,
37]. Reasons behind that can be a different study selection and the different methods used by the studies investigated. The results of the methods used also showed a discrepancy between the molecular method and the other methods (direct/microscopic approach). The molecular method showed a prevalence of 53% while the direct method showed only a prevalence of 40% and compared to different staining methods this discrepancy becomes even larger (trichrome staining at 17%, Giemsa staining at 35%, and iron h staining at 29%). These discrepancies come probably from the subjectivity of the microscopic approach, which depends on the examiner’s knowledge and experience, the number of fields examined, the type of microscope used (light versus phase contrast), the nature of mounting media, and the delay between sampling and examination especially for the direct method because here, the mobility of
Entamoeba gingivalis is the identification factor of the parasite as described by Bonner et al. [
11]. Prevalence based on gender was 43% in female patients and 47% in male patients, no significant differences were observed. These results are in accordance to previous researchers [
19,
22,
24]. When comparing the different sample methods, it is clear that the subgingival plaque sample results in higher prevalence compared to the dental plaque / saliva sampling method. This can be an indicator that
Entamoeba gingivalis is most commonly found in periodontitis compared to gingivitis and was also described by Bonner et al. in their previous research [
11]. Future research examining should also take the underestimated prevalence in dental plaque and saliva into account. It should be considered in any future research attempting to link oral parasites in health and disease especially given the availability of an experimentally validated protocol for such an intention. The application of quantitative PCR could have resolved the association between the parasite load and periodontal disease. By evaluating the prevalence of the two variations of
Entamoeba gingivalis, the strain diversity, that we did not address due to the lack of such research, should be considered.