Abstract
Fissures are often found in the lower lip. The median deepest and longest fissure, which is referred to as the median fissure of the lower lip, is found in approximately 50% of all people. The fissures seem to make it easy to perform the accordion movement of the lower lip to right and left. We hypothesize that the median fissure is deepest because it is subjected to the greatest amount of tension. In cases in which the mucosa of the lower lip becomes weak or in which tension to both sides becomes strong, a crack occurs ; this may lead to the development of inflammation. Microbiological examinations of 24 cases that presented inflammation of the median fissure, revealed Staphylococcus in 54.2%(most frequent) of the cases and MRSA in 20.8% of the cases (not rare). The other bacteria were considered to be part of the oral flora. Their detection rates were much lower；no bacteria were detected in 16.7% of the cases. This seems to be a big feature of median fissure of the lower lip. In contrast, there were no cases of angular cheilitis or inflammation of the nasal vestibule in which no bacteria were detected. Medical treatment is not always necessary, because cases in which bacteria were not detected were not rare. However, we should keep in mind the fact that MRSA was detected in one in five cases in involving inflammation of the median fissure of the lower lip.
