Squamous cell carcinoma arising in the lining of odontogenic cysts. Report of 5 cases

The lining of odontogenic cysts seldom gives rise to the development of a carcinoma. In a review of the literature by Gardner in 1975, 25 cases were accepted as such. In the present paper, 5 new cases are reported. These cases were encountered during a 14-year-period in which 292 oral carcinomas were registered, emphasizing the rarity of carcinomas arising from odontogenic cysts.     

Inhibition of plaque growth by zinc salts

Certain metal salts inhibit the growth of dental plaque. The effect of zinc salts was investigated because of contradictory reports in the literature. Using cultures of human plaque, artificial dental plaques were grown in vitro on aluminium strips. The effect of various zinc salts was examined by treating the strips intermittently with solutions of the salts during the period of growth. The action of mouthwashes containing zinc salts in vivo on plaque growth was determined in human volunteers.
All the water-soluble zinc salts that were tested gave a similar concentration-dependent inhibition of plaque growth in vitro . The effectiveness of the treatment was reduced by increasing the time allowed for growth after the final application of zinc.
Solutions of zinc (17–19 mM) as the citrate or phenolsulphonate salt, gave about 30% reduction in the extension of plaque along the gingival margin in vivo over 16 hours. Subjects with high rates of plaque growth with the placebo mouthwash were most affected by zinc salts. Increasing the zinc concentration to 30 mM did not further increase the activity. Previous reports of low activity of zinc against plaque growth in vivo are explained by too low a concentration of zinc or too low a frequency of application. The results confirm that zinc salts, including zinc citrate, inhibit the growth of plaque in vivo and in vitro .     

Layered silicone rubber technique for flasking removable partial dentures.

A method for flasking removable partial dentures using a layered silicone rubber technique has been described. The silicone investment protects the stone teeth from fracture during removal of the removable partial denture from the investment. Then the occlusal changes can be accurately corrected following processing.     

A survey of human genetics in the dental school curriculum.

A survey of American dental schools was conducted to determine the extent to which genetics is currently taught. Results indicate that there is a stronger emphasis at the postdoctoral level than at the predoctoral level and that the approach to teaching genetics tends to multidisciplinary. Some dental schools have already given organizational status to genetics and have instituted clinical activities in orofacial or craniofacial genetics. Considerable interest was shown in audiovisual materials and autotutorial programs in genetics. A greater emphasis on the teaching of genetics at the predoctoral, postdoctoral, and continuing education level is recommended. More trained orofacial geneticists are needed to support didactic and clinical activities within the dental schools.     

Ultrastructure of fenestrated capillaries in human dental pulps.

Dental pulps of both the primary and permanent dentitions were studied. Fenestrated capillaries were found at varying depths within the odontoblast layer in the root and crown portions of pulps. The fenestrae were in the attenuated part of the endothelial cell cytoplasm away from the nucleus. They averaged 60 nm in diameter and were bridged by a membrane or diaphragm approximately 7 nm thick.     

Effects of injury and inflammation on pulpal and periapical nerves

Several studies dealing with the reactions of dental nerve fibers to injury and inflammation are reviewed in this article. The subgroup of dental nerve fibers that contains calcitonin gene-related peptide (CGRP) was examined by immunocytochemistry at various times (1 to 35 days) after one of three degrees of injury: (a) Mild: Four days after making shallow cavities into cervical dentin of first molars of anesthetized adult rats, we found that CGRP fibers had sprouted into the subjacent odontoblast layer and dentin, and then returned to normal by 3 wk. (b) Intermediate: If the cervical cavities were acid etched, we found damage to the odontoblast layer, microabscess formation, and sprouting of CGRP fibers near the abscess, with subsequent formation of reparative dentin and healing. (c) Severe: If the pulp was exposed, a variety of reactions could occur, the most prevalent of which was a severe necrosis leading to development of periapical lesions. Analysis of the progressive stages of pulpal abscess and necrosis showed sprouting CGRP nerve fibers (a) at the retreating interface between abscess and vital pulp; (b) in periapical areas during onset of lesions; and (c) around chronic abscesses in granulomatous periodontal tissues. These studies are discussed in relation to various dental clinical problems such as hypersensitive teeth, episodic toothache, early onset of periapical lesions, dental anesthesia, and possible roles for sensory fibers and neuropeptides in tissue defense and healing.