In this study, 52 samples from DW and 20 ones from NDW were taken. Samples were obtained with sterile cotton swabs from the anterior and posterior surfaces of tongue at the midline site, and the candida spp. were counted. According to the authors said, to date, no similar study has been performed on comparing the colony counts of Candida spp. of the anterior and posterior surfaces of tongue, and other researchers have examined other oral sites .(13, 14)
In the present study a higher colonization of Candida species was seen in DW compared with NDW. This finding showed statistical significance when compared with NDW (P = 0.031). A similar trend was seen by some researchers that Candida colonization was higher among DW(12, 14). In the study of Prakash et al.(15) oral samples were taken from palatal mucosa of DW and NDW in the present study samples were obtained from anterior and posterior surfaces of tongue. In both study higher rate of candida colonization was seen in DW. Denture insertion accelerates the colonization and biofilm formation. The surface porosities of acrylic resin bring about modifications in the physiology and normal flora of the mouth. it led to the allusion of acidogenic microorganisms and Candida. therefore, oral health improvement in persons who wear removable prostheses has critical importance(16). Tissue contact surface of the denture increases the easy colonization of acidogenic microorganisms and Candida. the preparation a warm and humid space under the dentures, is the suitable condition for Candida colonization. Another issue in this context may be that removable dentures, obstruct the salivary flow from minor salivary glands and the free exchange of oxygen. Thus, the resultant low pH level facilitates the growth of C. albicans (17). Concerning the maintenance of denture hygiene in order to improve oral mucosal health, the participants were informed to regularly clean their dentures and keep them out of mouth overnight. It is the efficient ways to control yeast colonization in denture wearers.
The posterior surface of the tongue showed higher rate of candida colonization than anterior area, although only significant correlation was seen in DW (P = 0.006), but the same trend was followed in NDW, too. There was no significant difference between the yeast growth of C. albicans of posterior and anterior surface of tongue in NDW. it can be concluded that in patients with normal teeth, oral homeostasis can prevent candida colonization. So, in future studies, just the posterior surface of tongue could be sampled. loss of the end seal of the maxillary prosthesis competency may be the main cause(11). Thus, the Candida colonies formed on the tissue surface of the denture’s posterior region are more susceptible to spread rather than the colonies from the anterior part from the labial flange of the denture. This result should be the point of attention for choosing the best form of medicine for management of oral candidiasis in DW and NDW.
In all of participants, when the candida culture of the anterior surface of tongue was negative, also it was negative in the posterior region. This result was repeated for positive culture cases. The difference was significant in both groups. It could be concluded the fungal flora on anterior surface of tongue was similar to the posterior surface. It could be suggested that posterior one-third of the tongue is the best location for sampling for assessment of colony counts of candida species.
In this study like previous literatures C. albicans was the most common species. In similar studies, the most common type of Candida found in different parts of tongue was C. albicans(10, 14, 16, 18, 19) .on both surfaces of tongue C. albicans was isolated more in females than males in DW with statically significant power.
Females revealed significantly the higher distribution of Candida colonies in different parts of tongue. In a similar study by Loster et al.(20), Among all subjects, there was a statistically significant relationship between candida spp. growth intensity and gender. In each age group, the number of infection-free people was higher in men than women(20). This result can be justified by considering the hormonal changes in women and the presence of predisposing factors to anemia in them, which according to available references (1) is one of the important factors leading to candidiasis.
Although aging causes a progressive increase in Candida counts in the oral cavity with higher counts being observed among elderly DW but there was no significant relationship between Candida counts and age. This could be explained by the diminishing protective capacity of the immune system, which often occurs with aging(21).
There was not a statistically significant correlation between candida colonization and the duration of using denture in anterior and posterior of tongue. (P > 0.05). It’s worth mentioning resorption of alveolar bone is a serious and common clinical problem lead to reduction of retention and stability of dentures(22). Future studies with large sample size More samples may be shown a significant relationship between age and length of time of wearing denture and the average Candida colony counts.
It should be mentioned that one of the limitations of this study was lack of previous research studies on the topic and another one was the high cost of mycological findings due to sanction.