Direct smear technic has been adopted in almost all the study on exfoliative cytology of the oral cavity, but cytology of the mouth washings and garglings has not been made so far. Therefore the author determined the most satisfactory centrifuging factors of the mouth washings and garglings to collect cells in the previous study.
Now in this study cells were collected by means of centrifugation, membrane filter method and cell block method in normal healthy controls-25 newborns and sucklings, 30 adults. and 28 edentulous old persons with normal healthy oral cavity and in various clinical cases-24 malignancies, 6 benign tumors, 5 various other oral lesions, and 41 smokers. All the specimens were stained by Papanicolaou technic. I. NORMAL CYTOLOGY 1) Both nuclei and cytoplasms were larger in red and blue precornified epithelial cells, while somewhat smaller in orange keratinized cells showing pycnosis or disappearance of nuclei. 2) Fewer white blood cells were noticed in newborns, sucklings and old persons, while much more in the adults. These results may be due to the presence of gingival pockets, in other words the presence of teeth. 3) With the progress of age keratinized cells or those with keratinizing tendencies showed an increase, and those with regressive changes revealed the same findings. These results could be statistically proven significant and there was an aggreement between these cytologic and histologic findings. II. PATHOLOGIC CYTOLOGY
Centrifugation 1) Most of the exfoliated malignant cells showed blue cytoplasm, which could be considered they were low-keratinized immature cells. 2) Of 21 cases confirmed of carcinoma by biopsy cytology-positive cases were 81 per cent in direct smear method and 52 per cent in centrifugation befor operation and 35 per cent in the former and 50 per cent in the latter after operation. 3) Sarcoma and other various lesions were cytology-negative, but plasmocytoma associated with intraoral ulceration revealed cytology-positive. 4) More keratinized cells or those with keratinizing tendency could be noticed in both edentulous and dentulous persons in smoker's group than in non-smoker's group. And it could be found that 15 cases, i.e. 62.5 per cent of 24 malignant cases were smokers. Cell Block Method Epithelial cells of both normal and pathologic oral cavity showed so marked morphologic changes that this method was not suitable for examination of cell elements. However, cells showed crowdings so that keratinizing tendency could be easily noticed at first sight by the difference of staining and the tumor cells could be distinctly observed.
Membrane Filter Method No morphologic change could be seen and it was considred to be a useful method of diagnosis of malignancy, although cells overlapped each other. As a conclusion examination by centrifugation of the mouth washings and graglings was easy to collect cells, gave little irritation to the tissue and was a simple technic. It also could be repeated many times so that it was a very satisfactory method in cases of the following subjects: observation of postoperative progress, for example when the remnant of malignant tissue was suspected, examination of the cells after radiation therapy, early discovery of recurrence and examination of extensive lesions of the oral mucosa.