Histochemical studies on calcified tissues. I. Amino acid histochemistry of foetal calf and human enamel matrix

Aberrations involving the enamel epithelium in transplanted developing teeth

Structural changes that occurred when unerupted developing permanent teeth in dogs were transferred to other bony crypts or surgically prepared sockets were assessed histologically. The enamel epithelium and pieces of enamel matrix were often displaced from the developing teeth and contained within the dental sac. The epithelium underwent metaplasia, cysts frequently developed, and cementum was formed in moderate quantities when enamel matrix was directly in contact with connective tissues. Development of the crowns did not continue normally, and the teeth did not erupt.

A radiographic assessment of autologous tooth transplants in dogs

This study assessed structural and functional changes that occurred when teeth in dogs were transplanted at various stages of development. Unerupted developing permanent teeth were transferred to other existing bony crypts or to surgically prepared bony sockets. Erupted teeth with varying degrees of root formation were transplanted to other sockets, some with increased functional influences. The development, morphologic features, and relationships of the transplanted teeth were assessed radiographically at intervals ranging from seven to 150 days postoperatively.

A histological and histochemical study of developing teeth in Polypterus (Pisces, Actinopterygii)

The tooth cap matrix contained proteins of ectodermal and mesodermal origin which extended the data already available on teleost teeth and showed that a combined origin for the tooth cap should be regarded as a primitive feature of actinopterygian fish. Furthermore, the dual nature of the Polypterus tooth cap matrix suggested that evolution of tetrapod enamel did not occur within the actinopterygians. The collar tissue was an unmodified dentine, in contrast to its enameloid nature in many other actinopterygian teeth. The presence of a range of developmental states from unmodified dentine to hypermineralized enameloid within Polypterus teeth themselves and also in other parts of the dermal skeleton, as well as the combined origin of the tooth cap, demonstrates that the enamel/enameloid/dentine system forms a continuum of tissues that have diverged from one another by changes in the relative timing of developmental events and matrix production.

Histochemistry of lower vertebrate calcified structures. I. Enamel of the dogfish Squalus acanthius compared with mammalian enamel and homologous dentine

The enameloid and dentine of Squalus acanthius have been compared histochemically with those of Bos taurus. Squalus enameloid is much less reactive to a variety of stains or reagents than dentine or bovine immature enamel but it does have positive reactions with picromethyl blue, Mallory's and Van Gieson's stains, and Alcian blue. It stains faintly with Biebrich scarlet, indicating some anionic groups. Specific reactions for tyrosine, tryptophane, lysine, histidine, arginine, and cysteine are negative. Bos immature enamel is positive for cationic, anionic, and aromatic reactive groups by all test procedures, and dentine was positive for the anionic components. Bovine maturing enamel, however, is more similar in terms of lack of reactivity to Squalus enameloid but differed because the bovine enamel was moderately positive for tyrosine; tryptophane, and anionic groups and negative with Mallory's picromethyl blue and Van Gieson's stains. A fibrous transitional area between Squalus dentine and enameloid has staining reactions characteristic of both collagen and keratins.

A microspectrophotometric analysis of the effect of fluoride on immature enamel matrix protein of rat molar teeth

Over a 24-h period, Wistar rats from 4 litters, 6 to 9 days old, were given five intraperitoneal injections of a solution of 0.9% sodium chloride containing sodium fluoride (3 mg F/kg body weight). Within-litter controls were used. All rats were killed by decapitation 2 h after the final injection and the rat heads, cut sagittally, were processed for protein histochemistry. The intensity of staining of the protein in the enamel matrix of the upper jaw molar tooth buds was quantified using the two-wavelength method of microphotometry. A significant increase in the intensity of staining of fluoride-treated tissues over controls was observed with the histochemical methods specific for arginine (P less than 0.01), tyrosine (P less than 0.05), and cysteine (P less than 0.05). Other histochemical methods specific for amino acid groups failed to show any significant difference between fluoride and non-fluoride-treated enamel matrix.