Specific immunohistochemical localization of osteonectin and collagen types I and III in fetal and adult porcine dental tissues.

Affinity-purified antibodies have been used in combination with the peroxidase-antiperoxidase technique to study the distribution of osteonectin and collagen types I and III in porcine dental tissues. Tissue sections (2 mm thick), including unerupted (fetal) or erupted (adult) teeth, were fixed in periodate-lysine-paraformaldehyde, demineralized in 12% w/v ethylenediaminetetraacetic acid, and after embedding, 6 micron sections were prepared for immunolocalization. Strong staining for osteonectin was observed in dentine of unerupted teeth and in the associated alveolar bone. Light to moderate staining was observed in the dental pulp, stratum intermedium, stellate reticulum, and the reticular elements in the endosteal spaces. In erupted teeth, osteonectin staining in dentine was concentrated around dentinal tubules and the associated alveolar bone stained with variable intensity. Cementum was poorly stained. However, the periodontal ligament and reticular material in the endosteal spaces showed moderate to strong staining. Weaker staining was apparent in the pulp and lamina propria of the gingiva. In comparison, type I collagen showed a similar distribution to osteonectin in both fetal and adult tissues, whereas type III collagen was generally restricted to the periodontal ligament, reticular elements of the endosteal spaces, and Sharpey's fibers in bone and cementum. Both odontoblast and ameloblast layers in fetal tissues stained for osteonectin and type III collagen.

Elements in marginal seals at amalgam-tooth interfaces.

X-ray micro-analysis was used to determine the elemental composition of the tooth, amalgam, and base material of ten aged, amalgam-restored, posterior teeth after they had been fractured across the amalgam-tooth interface. Subsequently, replicas were used to remove marginal seal material from each interface for examination by x-ray micro-analysis. The results show that P and Sn were present in all marginal seal material analyzed. Ca, Cl, Cu, Fe, S, and Zn were present in the marginal seals of various numbers of specimens.

Effects of dietary fats on the fatty acid composition of enamel and dentinal lipids of rabbit molars.

The effect of dietary fats such as butter, lard, cottonseed oil, and hydrogenated cottonseed oil on the fatty acid composition of enamel and dentin lipids of rabbit molars was studied. The enamel and dentin of molars of all of the rabbits contained a variety of fatty acids, palmitic, stearic, oliec, linoleic, and eicosapentaenoic being the major ones. Enamal lipids were more unsaturated than dentinal lipids in all of the groups. A significant difference was noticed in the fatty acid composition of both the enamel and dentin between these four groups of rabbits. Linoleic acid content was highest in both the enamel and dentin lipids of rabbits fed cottonseed oil. There was no marked difference in the saturated-unsaturated fatty acid ratio in both the enamel and dentin among rabbits fed cottonseed oil, lard, and butter. It is concluded that tooth lipids are responsive to diets and are in direct equilibrium with dietary components.

The nature of covalent complexes of phosphoproteins with collagen in the bovine dentin matrix.

The bovine dentin matrix still contains some noncollagenous proteins after thorough extraction and decalcification. These have been obtained following digestion of the matrix by cyanogen bromide. Peptides containing non-collagenous portions were isolated by chromatography on diethylaminoethyl cellulose columns and fractionated on hydroxyapatite columns. Several fractions were obtained. The principal component was a complex between a highly-phosphorylated serine-aspartic acid-rich protein and a collagen peptide. These collagenous and non-collagenous moieties could not be separated from each other even under highly dissociative solvent conditions. After digestion with collagenase, the resulting phosphoprotein fraction still contained a few residues of hydroxyproline and hydroxylysine, and an enhanced content of proline, compared to the equivalent directly extractable phosphophoryn of the matrix. These data were interpreted as indicating that the phosphophoryn which is not extractable in 0.5M ethylenediaminetetraacetic acid is in fact covalently bound to some specific section of the matrix collagen. The covalent modification of the collagen matrix with highly acidic phosphoproteins may have an important role in the mineralization process.

Effect of dietary supplementation of glycine on caries development and lipids in rat molars.

The effect of dietary supplementation of glycine at a level of 4% on caries development and the lipid content of rat molar teeth was studied. The glycine supplementation caused a 65.7% reduction in caries development and a 15.1% reduction in lipid content. In a concurrent balance study, it was noted that the dietary glycine did not have any significant effect on the retention of either calcium or phosphorus by the rat's body. Changes in the fatty acid composition of the tooth and a reduction in growth rate were noted, however.

Lead, copper, and cadmium in teeth of normal and mentally retarded children.

Whole teeth obtained from handicapped children and from controls have been analysed for lead by anodic stripping voltammetry. No significant differences were found between the two groups. Teeth originating from the same patient showed systematic variations in lead content that are dependant on anatomical tooth type. The nature of this association is discussed. Analyses of sectioned teeth revealed, for cadmium and copper, unexpectedly large variations. High concentrations of cadmium found in the tips of deciduous incisor teeth indicate a probable contribution from maternal blood.

Substance P-like immunoreactivity in the pulp-dentine zone of human molar teeth demonstrated by indirect immunofluorescence.

Freshly-extracted human third molars were fixed in Zamboni fixative, demineralized with the mixture of EDTA and the fixative; substance P-like immunoreactivity (SPLI) was revealed by the indirect immunofluorescence technique of Coons. Substance P (SP) was observed in the pulp-dentine zone and the dental pulp. Some of SP-containing fibres ended at the odontoblast layer and did not reach the predentine; others terminated at the predentine surface or penetrated into the predentine. In the predentine, some of SP fibres accompanied odontoblast processes and ended near the mineralized dentine; others changed course transversely at various levels.

Mineralization differences between human deciduous and permanent enamel measured by quantitative microradiography.

The mineralization levels of erupted buccal enamel from 24 deciduous teeth were compared to those of 28 permanent teeth. Sections were prepared in a defined plane using a lapping machine which gave plano-parallel sections. Mineralization levels were recorded by quantitative microradiography at 25 equivalent anatomical sites in each section. Deciduous incisors and canines were compared with their homologous successors: overall mineralization levels were lower in the deciduous dentition, with no significant differences being found close to the amelo-dentinal junction, but highly significant differences being found in the outermost sites. Deciduous molars were compared with premolars, and were also relatively less mineralized. However, deciduous molars did not show the consistent diminishing occlusocervical gradient observed in all other tooth types tested; on the contrary, they showed a cervical reversal with higher values than permanent premolar enamel. These results confirm the generally lower mineral levels in deciduous enamel, and provide quantitative information on site-specific mineralization levels.

Lead in teeth of weanling rats received via the maternal drinking water.

Pregnant rats were dosed with 0, 3 or 10 parts/10(6) lead (as acetate) in their drinking water, during pregnancy and during lactation until 21 days post partum. The litters were killed at the age of 21 days and the incisors, first, second and third molars analysed for lead by atomic absorption spectrophotometry. The findings confirmed that even at low concentrations lead has an affinity for hard tissues. The mean lead levels of the teeth of the three groups differed at the 1 per cent level. Pb levels of the first and second molars and the incisors also differed at the 1 per cent level. No significant differences between the four types of teeth within a group could be demonstrated. The no-effect level of Pb administered in drinking water, to the mother during lactation, and during pregnancy, was lower than 3 parts/10(6).

Tooth wear, solubility and fluoride concentration of molar-tooth surfaces in rats maintained on simultaneous or separate intake of food and fluoridated drinking water.

Eighty rats, 20 days old, were fed a hard pellet diet and deionized or fluoridated (25 parts/10(6) F-) drinking water respectively for 40 days. Half were maintained on simultaneous food and water intake for 3 h, daily, and the remainder on separate intake of food for 3 h followed by drinking water for 3 h, daily. Scanning electron micrographs of the occlusal surface of right maxillary first molars were used for scoring wear. The mandibular and left maxillary molar surfaces were used for solubility and fluoride concentration determinations. Intake of food and water separately did not affect wear significantly, whereas solubility and fluoride concentration of the molar surfaces were significantly increased. Wear, solubility and fluoride of the molar surfaces respectively were highly significantly increased in the rats provided with fluoridated water. Increase in fluoride uptake is due in part at least to the increase in sites available for uptake due to tooth wear. Acid dissolution of worn tooth-surface enamel is greater than that of intact enamel.

Characterization and immunocytochemical localization of dentine phosphoprotein in rat and bovine teeth.

Dentine phosphoprotein (DPP) was isolated from unerupted bovine molars and from rat incisors. The proteins were characterized biochemically and used to immunize rabbits and guinea pigs. Antibody activity was investigated by enzyme-linked immunosorbent assay (ELISA). Guinea-pig anti-rat DPP did not cross-react with bovine DPP, but rabbit anti-bovine DPP did cross-react with rat DPP. Anti-rat DPP antiserum was applied to cryotome sections of rat molar tooth germs and DPP immunoreactivity was seen in dentine, odontoblasts, odontoblast processes and pre-ameloblasts. Anti-bovine DPP antiserum reacted positively in bovine dentine and dentinal tubules. When this antiserum was applied to rat tissue, predentine was positive but dentine was negative. Adsorption experiments with DPP, purified by methods including and excluding precipitation with calcium, suggested that non-calcium precipitable DPP is present in rat predentine. Rat and bovine DPP are thus species-specific and DPP is synthesized by the odontoblasts, transported through their processes and secreted into the dentine.

Lead content of deciduous molar enamel in Finland, as measured by proton-induced X-ray emission.

The lead content of deciduous molar enamel was measured with an accurate physical technique based on proton-induced X-ray emission. The absolute values were calibrated according to the animal bone standard of the International Atomic Energy Agency. The results obtained from five different communities indicated little difference between communities in the lead content of the deciduous molar enamel of children born in 1960-1975. The overall mean for all samples analyzed was 3.2 (SD 1.6) micrograms/g (N = 120); the highest individual value measured was 10.0 micrograms/g. Judging from the lead content of the teeth, the general population in Finland does not yet seem to be exposed to detectably higher amounts of artificially occurring environmental lead, neither in urban nor in rural areas. It would seem that naturally occurring environmental lead still plays a decisive role in the integrated long-term exposure in Finland.

Lead in teeth: the influence of the tooth type and the sample within a tooth on lead levels.

Different sections of permanent teeth have been sampled and the lead levels estimated using carbon furnace AAS. Very high levels of lead (500-3400 micrograms g-1) and other trace metals (Cd, Cu, Fe and Zn) occur on the surface of the teeth, falling off rapidly a few micrometers into the teeth. Lead levels in the bulk enamel of incisors vary depending on the position within the tooth, the highest values occur on the lingual side near the gums and the lowest levels on the labial side near the tooth top. The ratio of the concentration of lead in enamel to dentine and to circumpulpal dentine was found to be 1:2:6, and within the dentine the lead levels were highest in the root dentine. The root dentine in the permanent teeth of eight, near complete or representative, sets of teeth was analysed for lead. The ratio ([Pb]tooth/[Pb]total set) decreased in the order: first molars greater than central incisors greater than lateral incisors greater than canines greater than premolars greater than second molars greater than third molars. This order inversely correlates with the age of formation or eruption of the teeth, i.e. the older teeth have the highest levels of lead in the dentine. Dentine appears to be the best material to use to estimate lead, particularly in relation to the integrated lead intake of a person. Dentine lead was determined in a small sample of deciduous teeth obtained from children living in rural areas. The levels were found to be slightly less than for children living in new housing urban areas and significantly less than for children living in older houses of urban areas.

Microhardness of molar teeth in cattle with fluorosis.

Cattle were fed forage containing fluoride at a yearly average of 40 mg of fluoride/kg of forage for 5 or 6 years from the time they were 4 months of age. A significant (P < 0.05) negative correlation was observed between the average microhardness of the 3rd premolar and 3rd molar enamel and the fluorosis score of the 2nd incisor. The microhardness of fluorotic outer molar enamel was only 41% of the microhardness values of enamel from control teeth not exposed to long-term fluoride, and electron probe microanalysis indicated increased fluoride concentrations in the molar coronal cementum, enamel, and dentin. Increased incisor fluorosis scores were diagnostic of softer molar enamel. When severe, such changes may have a detrimental effect on the proper mastication and subsequent nutrition of cattle with fluorosis.

Prediction models for 90Sr in shed deciduous teeth and infant bone.

Shed deciduous teeth were collected in 1966-69 in Denmark, the Faroes and Greenland from children born in the period 1953-63. 235 samples of crowns were analysed for 90Sr. The 90Sr levels in deciduous tooth crowns were related to the fall-out rate and the accumulated fall-out. The tooth levels in children born in 1950-62 could be described with the same equation as the 90Sr bone levels in 1-yr-old infants born in 1962-68. The prediction models for 90Sr in teeth and bones showed that for given amount of fall-out the Faroese levels became nearly twice as high as the Danish. The maximum teeth and bone levels were found in children born in 1963, where the Faroese level was estimated from the prediction model to be 24 pCi 90Sr/g Ca.

Tooth lead levels in Birmingham children.

The mean lead content of deciduous teeth from children living in the city of Birmingham (U.K.) has been shown to be 11.8 ppm dry weight, irrespective of the sex of the donor. Lead content varies according to type of tooth, and there is a gradient from incisors, with the highest level, to second molars, with the lowest. A relationship was shown between age of donor and lead content of canines and (when lognormalized data were considered) first molars. We were not able to demonstrate a correlation between tooth lead levels and residence near a potential industrial lead source, and we conclude that pollution from a general source is responsible for the body burdens we found.

Lead content of deciduous teeth of children in different environments.

The lead content of teeth of children in five different environments has been measured to determine the relative contribution of different sources of lead. The importance of lead paint in children living in dilapidated housing is clearly observed, but no effect attributable to automobile exhaust or industrial emissions is apparent. High lead levels were found among children living in new public housing projects within the high lead area of the city, even though a lead paint problem presumably should not exist in the projects themselves. The data are analyzed to determine the frequency with which excessive lead contents occur in the problem area in comparison to a low risk area.

[Boron in dental hard tissues studied by 11B(p,alpha)8Be nuclear reaction]. / Il boro nei tessuti duri dentari studiato con la reazione nucleare 11B(p,alpha)8Be.

Boron's low atomic number and low concentration make its measurement in hard dental tissues difficult. Using nuclear reaction, the 11B(p,alpha)8Be*, enamel, dentine and radicular cement of 18 dental elements, ten healthy and eight decayed teeth, both permanent and deciduous were studied. The highest Boron concentrations were found in the two most superficial microns of the vestibular enamel in non-decayed incisors, particularly deciduous ones. Premolar and molar teeth showed lower Boron concentrations than frontal ones, decayed teeth revealed hardly any Boron. In confirmation of the prevailing exogenous contribution of this karyostatic trace element, on average, Boron concentrations were 2.5 times as high as dentine and 10 times as high as cement.