SCANNING ELECTRON-MICROSCOPE STUDY OF THE HEALING MOLAR TOOTH EXTRACTION SOCKET IN THE RAT

Healing molar tooth extraction wounds in rats were examined by scannin g electron microscopy from 15 minutes to 40 days following tooth remov al. The wound epithelium, which was derived mainly from the gingiva bu t also from the cheek and hard palate, migrated beneath the superficia l socket contents. The contents were lost between 5 to 11 days, thus l eaving a central epithelial-lined depression. This decreased in width with time as the level of the wound epithelium approached that of the hard palate but was still present at 40 days. Between 5 and 7 days, th e wound epithelium became more regular. However, from 11 days on, it b ecame more irregular with increasing numbers of saucer-shaped depressi ons, circular defects and circular whorls of epithelial cells. The sur face structure of the epithelial cells changed as it migrated and matu red. The initially plump, then flattened cells mostly had smooth areas along with variable numbers of irregular microridges and microvilli, although cells derived from the cheek had only smooth surfaces. With f urther maturation, all cells developed a regular honeycomb surface pat tern of interconnecting microridges similar to that on the hard palate . Why the wound epithelium became more uneven after 11 days is not kno wn.