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Junctional nevi of the oral mucosa are rare and may be precancerous. A patient who had an enlarging junctional nevus of the labial mucosa with an adjacent lentigo simplex was studied by light and electron microscopy. On the basis of morphologic similarities—dendritic appearance, lack of desmosomes, proliferative melanin production, and lack of cytoplasmic fibrils—it appears that the nevus cell most likely develops from melanocytes. The reason for the transformation from melanocyte to nevus cell or junctional nevus cell hyperplasia is unknown.

Frozen sections of 75 decalcified human teeth with root surfaces exposed to the oral environment during periodontal disease were examined for the presence in cementum of “pathologic granules” (Bass 1951, Benson 1963). In 72 of these teeth granule-like formations were found in exposed cementum. In only one instance were the granules also found under an unexposed root surface. A possible explanation for this exception was presented. The cemental granules do not appear to be artifacts of fixation, decalcification, or freezing. Mineralized ground sections of exposed roots did not exhibit any structural changes resembling the granules. However, upon decalcification the granules appeared. This suggests that areas from which the granules arise are filled with calcified material.