Although the prevalence of MRG in earlier studies ranged between 0.9% and 5.4%,9–11
in a previous study12
carried out in our country was determined a prevalence rate of 0.2%. Our 0.7% is higher than this previous observation in the Turkish population. Rogers and Bruce4
stated that men are affected 3 times more often than women. However, Wright13
showed a 4:1 female predominance in 28 MRG patients. Avcu and Kanli12
also found that the female to male ratio of 12 MRG patients in Turkish dental outpatients was 11:1. Both rates are remarkably different from our result (1:2). We enable to explain why MRG is more prevalent in males in light of the literature.
Tapper-Jones et al14
showed that smoking increased the candidal carrier rate in both diabetic and healthy subjects. But, Willis et al15
found that diabetic patients with oral candidiasis who were smokers had significantly higher candidal load than diabetic patients with oral candidiasis who were exsmokers or who did not smoke. Joseph and Savage1
stated that the prevalence of MRG is higher in immunosuppressed patients, diabetics, and in patients on broad-spectrum antibiotics. Also, Guggenheimer et al16
pointed out that MRG is one of the most observed oral candidal infections in insulin-dependent diabetes mellitus patients. This knowledge is compatible with the result of our report that diabetes is important to the risk of MRG.
Some studies showed that smoking, dental prosthesis, and small traumas, alone or in combination with each other, appear to be important predisposing factors for oral candidiasis.2,17
Gumru et al18
stated that denture stomatitis is commonly related with MRG. However, Farman and Nutt19
revealed that neither the association between MRG and denture stomatitis nor the association between MRG and denture wearing was statistically significant. Since none of our MRG patients had removable denture prosthesis, we are in agreement with Farman and Nutt.19
The importance of tobacco smoking and denture wearing in the etiology of MRG in 39 patients was evaluated by Arendorf and Walker.20
Most of the MRG patients (85%) smoked tobacco compared with the 39 healthy, age and gender-matched controls (41%). The number of MRG patients who were both tobacco smokers and denture wearers was significantly high, suggesting that these local factors may play a role in the development of MRG. In contrast to Arendorf and Walker,20
a rate of 33.3% for smoking in MRG patients was observed in our study.
There have been many studies on MRG, all of which appear to very strongly implicate Candida albicans
as a probable cause.21
published a report of 10 cases of MRG, all of which showed fungal hyphae in the keratin layer in histological sections. Farman and Nutt19
stated that there was a highly significant statistical correlation between MRG and Candida
species. Cernea and colleagues,23
were able to culture Candida
species from MRG. Ullman and Hoffman25
found Candida albicans
in 18 out of 22 MRG lesions examined mycologically. We found higher a candidal growth rate in MRG patients than in the controls. Our findings were consistent with earlier data and apparently demonstrated the relation between MRG and Candida.
We also investigated the presence of Candida
and bacteria species in MRG in this study. While there was no data about both Candida
and bacteria species in previous reports, we isolated C. albicans, C. kefyr, C. tropicalis, C. krusei, and C. glabrata
from 18, 3, 2, 2, and 2 patients with MRG, respectively. In addition, normal oral microbial flora species such as Streptococcus spp., Corynebacterium spp.,
and Neisseria spp.
were isolated from MRG lesions and control patients in bacteriological examination.
Arendorf and Walker20
reported that 44% of the population harbor candidal organisms as part of their normal oral flora, and they also stated that the tongue is the primary oral reservoir for Candida.
In particular, the midline of the tongue is suitable for intense overgrowth of Candida organisms. Whitaker and Singh26
suggested that since the tongue maintains close contact with the palatal mucosa during swallowing and at rest, the area of the tongue contacting the palate corresponds well to the area in which MRG develops. Also Farman24
suggested that an impaired blood supply to the mid-dorsal surface of the tongue might predispose it to the development of candidiasis and, presumably, to the consequent loss of filiform papillae.
When MRG is found in association with palatal inflammation corresponding to contact with the involved area on the tongue, it is called kissing
lesion; immunosuppression should be suspected and it has been considered a marker of AIDS.4
In our current study, only 3 of the MRG patients had kissing lesions in the palatal region. The Candida
species of kissing lesions were the same as those of MRG. Therefore, this finding may suggest that these lesions occur as a result of prolonged contact between the Candida
-infected midline dorsum of the tongue and the hard palate.
MRG is often an asymptomatic lesion. Likewise, all of our cases were asymptomatic. Thus, they did not need any treatment; however, these patients have been kept under observation. Since the presence of kissing lesions on the hard palate may be a cause for concern about HIV, all patients with kissing lesions were checked for HIV in the hospital, and it was observed that there was no HIV in our subjects. Although Delemarre and van der Wall27
have stated that there is no clear relationship between MRG and cancer, there have been 3 previous reports of malignant transformation of MRG.28,29
In our opinion, especially if the lesion represents ulceration or if it is solid to palpation, the possibility of malign transformation should be considered and biopsy performed.