In situ remineralization of early enamel lesions by a fluoride chewing gum was studied. Human enamel specimens with subsurface lesions were mounted in removable lower appliances for 6 adults. Subjects used a F-free dentifrice 3 ×/day and chewed five sticks/day for the F gum group (0.1 mg F/stick) or five sticks of sugarless gum. No gum was chewed for controls. Surface microhardness was performed on: (1) sound enamel; (2) lesions; (3) after intraoral exposure, and (4) after acid-resistance testing (ART). Separate specimens were etched and measured for F uptake and image analyses on microradiographs were performed for all regimens. ΔZ values were calculated and converted to percent of mineralization. Values for F gum were significantly higher (p > 0.05) than non-F gum and controls for ART, percent remineralization, and F uptake up to 70 μm depth.

Human primary teeth in the stages of late root formation, mot completion and root resorption were impregnated with silver to allow study of the distribution of nerves in the pulp.Neural trunks composed of many individual, myelinated nerve fibers enter the apical foramen of primary teeth and pass in a coronal direction, often in close association with blood vessels. Neural trunks in the crowns of the teeth divide into smaller branches, which divide further into myelinated nerve fibers, which become interwoven to form the parietal layer (plexus of Raschkow). An occasional unmyelinated fiber leaves this zone and passes into the odontoblastic layer of cells where it appears to terminate with no specialized ending apparent. No nerves were seen to enter the predentin or dentin.As primary teeth begin to undergo root resorption, degenerative changes such as thickenings, varicosities and fragmentation appear in the nerves. The quantity of neural tissue also decreases. The greater the amount of resorption, the greater are the degenerative changes. In teeth in which the roots are almost completely resorbed, only a small number of nerves remain.The pattern of distribution of nerves in primary teeth is observed to be similar to that of permanent teeth. The density of the innervation of the primary teeth, however, is not found to be as great as that of permanent teeth.The innervation of human primary teeth has received little attention when compared to similar research on permanent teeth. The lack of interest in the distribution of pulpal nerves in the primary dentition may result from the belief that the pulps are similar to those of permanent teeth or that primary teeth are not a lasting component of the oral cavity. Clinicians have long been aware of a lower sensitivity to pain in primary teeth than in permanent teeth which may be due to differences in number and/or distribution of their neural components. Another area in which information is lacking involves changes in the neural tissue of the primary teeth during the period of root resorption (and exfoliation). The present investigation is concerned, therefore, with the distribution of nerves in primary teeth during stages of root formation, root completion, and root resorption.Bradlaw ('36) studied neural degenerative changes in both human and animal primary teeth using a variety of silver impregnation techniques. He observed these changes to occur prior to exfoliation in some teeth but not in others. Mohuiddin ('50) studied the primary and permanent teeth of the cat by means of both the Romanes' and Bielschowsky silver methods. The permanent and nonresorbing primary teeth exhibited patterns of innervation similar to those observed for human permanent teeth by Rapp, Avery and Rector ('51). All of these investigators observed neural fibers within the pulp to form arborizations or a parietal layer (plexus of Raschkow) adjacent to the dentin and then terminate between or among the odontoblasts. A few nerves were found in the predentin and dentin, but none were obse...

Dose-related remineralization of enamel lesions was studied in situ. Enamel specimens with subsurface lesions were mounted on lower molars bilaterally and exposed to five regimens: (A) control with a F-free dentifrice three times daily; (B) NaF dentifrice brushed three times daily; (C) fluoride-releasing device (FRD; 0.07 mg F/day release rate) plus F-free dentifrice; (D) FRD (0.232 mg F/day) plus F-free dentifrice, F/day and (E) FRD (0.232 mg/F/day) plus NaF dentifrice. Resting and stimulated saliva samples were obtained for salivary flow and F content determinations. Twenty-eight subjects participated in this double-blind, random-assignment crossover study. After 50 days the enamel specimens were recovered, sectioned, microradiographed, and scanned with image analysis. Regimens D and E demonstrated approximately 30% additional remineralization as compared with to controls, and regimens B and C showed 13.7 and 10.5% increased remineralization as compared with to controls. The increased remineralization of the regimens generally paralleled the increase in salivary F and clearly demonstrated a dose-related response which was some threefold in relation to release rate, salivary F, and percent remineralization.

This study was carried out to determine the effects of denervation of the pulp organs of teeth, particularly on the odontoblasts and their processes. Therefore, resection of the inferior alveolar, cervical sympathetic, or a combination of both types of nerves supplying the mandibular incisor teeth of New Zealand white rabbits was performed and the results compared to adjacent, unaltered teeth. Neural stains were used to evaluate the presence or absence of nerve elements, while histochemical and titrametric methods were employed to determine the presence, location and concentration of cholinesterase enzymes in these teeth. Dilation of blood vessels was noted after cervical sympathetic resection and larger nerve trunks as well as peripherally located fine fibers were absent in the pulps following inferior alveolar nerve resection. Further, irregular dentin formation and associated small openings in the tips of the teeth were observed after nerve resection. Titrametric analysis indicated a significant decrease in the concentration of cholinesterase in the pulp organ of incisors 15-19 days after resection of either the inferior alveolar nerve or both inferior alveolar and cervical sympathetic nerves. Only a slight decrease in the concentration of cholinesterase was noted after removal of the cervical sympathetic nerve alone. Histochemical results confirmed a decrease in cholinesterase after resection of the inferior alveolar, cervical Sympathetic or both nerves. The concentration of the oxidative enzyme, succinic dehydrogenase, however, increased after all three types of nerve resection. This increase was apparent particularly in the odontoblastic cells underlying the predentin.

Remineralization of early enamel lesions was studied in situ using a F chewing gum or a F-releasing device (FRD). Enamel specimens with subsurface lesions were mounted in removable lower appliances in 6 adults. A F-free dentifrice was used for all regimens. Test groups chewed five sticks/day (0.1 mg F/stick), or one FRD (0.5 mg F/day) was mounted in the midline of the appliance. The microhardness was measured after the 21-day intraoral exposure, and in vitro acid resistance testing was performed. Separate specimens were used to measure F content or changes in mineral density. Comparable values for both F gum and FRDs were higher (p > 0.05) than controls for acid resistance testing and percent remineralization. The F content for FRDs exceeded that of both F gum and controls.