In general, many kinds of the pathologic changes have been found to occur in oral soft tissues including buccal epithelium : Erythroplakia, Lichenplanus, Candidiasis, Discoid lapus erythematosus, White sponge nevus, Submucos fibrom, Habitual cheek-biting, Allergic stomatitis, etc. A rare change was encountered on buccal epithel of a patient three days after his partial denture had been set in his mouth. The patient did not complain anything about the denture, but the widely diffused linear eminence was observed on the buccal epithel along the interocclusal line as well as the pressure marks on the lower lip. The appearance and the location of the former symptom were well suggestive of the Lichenplanus or the Habitual cheek-biting. As for the Lichenplanus, approximately 85% of its symptoms are likely to appear on the buccal epithel, especially most frequently at the site corresponding to the occlusal plane or the interocclusal line. It shows various aspects such as reticular, punctate linear, plaque and papular form etc. according to its various etiological factors. One of the characters of the Lichenplanus is that the symptoms would not tend to disappear swiftly after the prosthetic device is removed from the oral cavity. In the present case, the symptoms almost disappeared twenty four hours after the removal of the denture although they were quite similar to those of the Lichenplanus. Consequently the case may not be identified with the Lichenplanus. On the other hand, there could be found in this case neither the patient's awareness of biting his own cheek itself, submucos hematoma, nor subsequent ulcerative change which are the typical symptoms of the Habitual cheek-biting. However, the possibility of regarding it as the Habitual cheek-biting might not completely be eliminated since it is the cheek-biting that occurs the most frequently at the site of the buccal epitheljum corresponding to the occlusal plane in association with the denture. From this point of view, several modifications of the design were tried on the type of clasp and the bucco-lingual position of artificial teeth of the denture. The symptoms still reccurred by setting every modified denture in his mouth so far as it was the removable partial one. Finally the occurrance of the symptoms was almost diminished only by converting the removable denture into the fixed bridge. It is probable that the habitual occlusion in this patient might have been effectively changed by the bridge itself.
