Experimental induction of an incomplete hard-palate cleft in the rat

Incomplete clefts of the hard palate with soft-palate integrity are among the rarest malformations found in human beings. They appear as oval-shaped openings in the midline of the hard palate and do not extend along its whole length. The amniotic-sac-puncture technique was used to induce such clefts in 10 percent of a group of rat fetuses at day 15.3 of pregnancy. The upper jaws of such fetuses, either 17.3 or 21.3 days old, were examined in the scanning electron microscope and in serial Epon sections. At day 17.3 incomplete clefts of the hard palate were extending toward the soft palate, with the anterior portion of palatal shelves still in the vertical position and with the soft palate already fused. At day 21.3, the incomplete hard-palate clefts were smaller in both extension and width. These observations support the idea that fusion of the soft palate can occur independently of fusion in the hard-palate region.     

Effects of irradiation on grafted skin

The reaction of grafted skin to irradiation was studied in the rat and the optimum time for irradiation postoperatively was determined. There was a close correlation between the radiosensitivity and the vascularity of the graft and its recipient bed. Grafts showed different reactions depending on the time of irradiation after grafting. Those in the early hypovascular stage showed reactions similar to those of normal control skin. Severe reactions were observed in the hypervascular stage. Grafts in the late hypovascular stage showed more moderate reactions.     

Peripheral calcifying epithelial odontogenic tumor

Most of the calcifying epithelial odontogenic tumors (CEOT) are central lesions of the jaws, but the CEOT occurs infrequently on the gingiva. A cases of peripheral CEOT arising in the right upper molar gingiva of a 31-year-old Japanese woman is presented. A direct communication between the overlying gingival epithelium and the tumor was found by examination of serial sections. As a result, it was thought that one of the sources of peripheral CEOT might be gingival epithelium with potential proliferative activity.     

Bifid mandibular nerve as a possible cause of inadequate anesthesia in the mandible

Failure to achieve complete mandibular anesthesia is a problem that often occurs. The explanations include faulty anesthetic solutions, faulty technique, and anatomic or physiologic variations. Bifurcation of the mandibular nerve, rarely mentioned in the literature, may be a cause of inadequate anesthesia in a small percentage of cases.     

Systemic bone disease in patients with mandibular atrophy

Although the etiology of alveolar ridge resorption is unclear, the labile alveolar bone may be highly sensitive to changes in systemic bone mineral content. Ten patients presenting with severe mandibular atrophy were studied by photon absorption densitometry. Four patients exhibited a significant reduction in radial midshaft mineral content. All four had systemic bone disease revealed on undecalcified histological sections although serum biochemical studies were normal. Common factors were severe mandibular atrophy, decreased bone density, and systemic bone disease. Photon absorption densitometry is suggested as a screening mechanism for systemic bone disease in patients with severe mandibular atrophy.