Dental materials: 1974 literature review part II

This paper, which is presented in two parts, reviews the work on dental materials published in 1974. Included in Part I were sections on amalgam, casting alloys, denture base polymers, composite filling materials, soft lining materials, fissure sealants, impression materials, dental ceramics and model and die materials. A review of the literature relating to cements, dental implants and dental biomechanics is presented in Part II.     

The effect of fluoride pretreatment and ascorbic acid on bone growth in tissue culture

The addition of ascorbic acid to tissue culture media was found to increase the collagen and mineral content of bones grown in vitro both effects resulting apparently from an increased rate of collagen synthesis. Ascorbic acid also increased the solubility of the bone collagen, possibly by increasing the accumulation of newly synthesized, soluble, collagen in the bone at a rate faster than the formation of crosslinkages between the collagen molecules. Pretreating bone in vitro with fluoride increased the weight of cultured bone primarily by increasing the mineral content. The effect was greatest in the presence of a low rate of collagen synthesis. When collagen synthesis was accelerated by ascorbic acid, fluoride pretreatment caused a lesser increase in bone mass and actually depressed collagen synthesis. It would appear, therefore, that the effect of fluoride pretreatment on bone growth is dependent in part on the rate of collagen synthesis by bone cells. Fluoride pretreatrnent decreased the solubility of the collagen matrix of bone indicating an affect on intermolecular crosslinking. The increased degree of crosslinking due to the fluoride pretreatment may account, in part, for the inhibition of bone resorption in tissue culture.     

Histometric analysis of interradicular bone in protein deficient animals

A histometric analysis of bone density was made in the interradicular bone of rats fed either a powdered protein free diet, pair-fed with an isocaloric 27 % casein diet or fed control diets, ad libitum, of either soft or hard consistencies. A marked osteoporosis was found in the two nutritionally restricted groups. The pair fed animals showed a greater osteoporosis than the protein deficient animals. These results were statistically significant (p = 0.001).