Lipids of supragingival calculus.

The matrix of supragingival calculus constitutes 15.7% of the calculus dry weight and contains 54.9% protein and 10.2% lipids. Of the total lipids, 61.8% are represented by neutral lipids, 28% by glycolipids, and 10.2% by phospholipids. The neutral lipids exhibit a high content of free fatty acids (63.9%) and triglycerides (15.8%). The glycolipids are comprised of simple glycosphingolipids (17.2%), mainly lactosyl- and glucosylceramides, and of neutral and sulfated glyceroglucolipids (82.8%). The phospholipids contain large quantities of phosphatidylethanolamine (34.2%) and diphosphatidylglycerol (25.5%). Comparison with salivary and submandibular stone lipids indicates that both saliva and bacteria contribute to the lipid content of supragingival calculus.

The crystalline components of dental calculi: human vs. dog.

Dental calculus from the dog was found to consist principally of the calcite form of calcium carbonate mixed with small amounts of apatite; other calcium phosphates, consistently present in human calculus, were not present in dog calculus. Precipitable calcium salts from human saliva were mainly apatite; for the dog the principal precipitated salt was calcium carbonate (calcite form).

Microbeam x-ray diffraction analysis of dental calculus.

The crystalline components of human dental calculus were investigated using microbeam x-ray diffraction analysis. Hydroxyapatite and octacalcium phosphate were most frequently found in that portion having porous and zonal structure. In the portion of the homogeneous illustration showing high calcification, whitlockite is a main component. Brushite was unexpectedly rare, and no calcite was detected in any portion of human dental calculus. The mechanism of the formation of dental calculus being considered in this paper is that octacalcium phosphate or brushite is formed during the initial stage of calcification of dental plaque, and is gradually hydrolyzed and transformed into hydroxyapatite and/or whitlockite.

Characterization of calculus matrix calcification nucleator.

The nucleator of dental calculus matrix calcification, in vitro, was analyzed. Attention focused on proteolipid singularity, amino acid composition and related polarity, and phospholipid components. The data were compared to those of the nucleator of Bacterionema matruchotii calcification.

Formation of calcium phosphates in saliva and dental plaque.

This is an X-ray diffraction study of the mineral phases in saliva and early dental plaque. The salivas studied came from patients with cystic fibrosis (CF), those with asthma, and heavy and light calculus formers. One-week old plaque was studied from individuals who are heavy, moderate, and light calculus formers.

In vivo remineralization of human enamel and dental calculus formation.

The aim of this investigation was to determine the inorganic composition and the surface morphology of remineralized enamel areas and of dental calculus in heavy-calculus-formers (five subjects) and to compare these results with those of non-calculus-formers (two subjects). Electron probe micro-analysis (EPMA) was carried out on sound, acid-etched, and in vivo remineralized enamel samples from heavy- and non-calculus-formers. The mean values of Ca, P, Na, Mg, Al, Si, S, Cl, and K were compared with the SEM morphology. EPMA measurements showed no significant differences in the Ca/P ratio of the surface layers of prism-oriented and/or homogeneous enamel remineralization. The variations of remineralization pattern after acid-etching are similar in teeth from heavy dental-calculus-forming patients and in teeth from non-calculus-formers. The SEM appearances of remineralized areas and of the inner surface of mature dental calculus must be considered to be totally different. The experiments carried out suggest that the remineralization of enamel is not related to the formation of calculus.

Relations between early dental calculus production and calcium and phosphate parameters of salivary fractions.

A pilot study was carried out to obtain an idea of the strength of the relations between early mandibular calculus production in humans and amounts and concentrations of bound calcium and phosphate in three salivary fractions. The salivary fractions were: (1) the spontaneous precipitate from incubated whole saliva, (2) the spontaneous precipitate from incubated centrifugal (20,000 X g) saliva supernatant and (3) the fresh centrifugal saliva sediment. Strong and highly significant correlations were found for the amount and concentration of calcium in the fresh sediment and whole saliva precipitate fractions. Although the correlations for the calcium parameters of the saliva supernatant precipitate were not significant, there were significant differences in these parameters between low and high calculus formers as determined by Student's t test. Relations between calculus production and amount and concentration of phosphate were weaker and not significant for all fractions. The data suggest that the amount or concentration of calcium in fresh saliva sediment is an important determinant of early mandibular calculus production.

A case report of unusual dental calculus formation.

A case is presented in which an unusual amount of intraoral calculus was seen in a 59-year-old woman. The deposits completely covered all surfaces of most teeth and extended over the facial and lingual gingivae. The relationship between certain chemical salivary parameters and heavy calculus formers is briefly described.

Salivary composition and calculus formation in patients undergoing hemodialysis.

The purpose of this report is to provide further information regarding oral changes in patients with chronic renal disease who are undergoing hemodialysis. Quantitative changes in salivary flow rate and alterations in the composition of stimulated and unstimulated sliva were studied along with the rate of formation of supragingival calculus. Results revealed a lower salivary flow rate and increased salivary urea concentration in the dialysis group. Dialysis patients also formed more heavy calculus.

Analytical transmission electron microscopy of the distribution of elements in human supragingival dental calculus.

Thin sections of supragingival calculus from lower anterior teeth of 26 subjects were examined. From each specimen, an average of 10 spectra was collected from a densely-mineralized area less than 100 micron diameter. Only spectra showing peaks for minor elements or unusual Ca:P peak ratios were collected, stored and analysed semi-quantitatively. Ca:P weight percentage ratios varied within each specimen. Although most lay within the range 1.6 to 1.8, ratios of less than 1 and greater than 22 were obtained. The latter indicated the presence of some P-free Ca salts. The minor elements Mg and Zn occurred most frequently but the concentration within a specimen varied from the undetectable up to approx. 3 per cent by weight for Mg and 1 per cent for Zn. Low peaks for Ti, Ni, Co, As, Sr, Zr, Mo, Cd and Sn occurred in 1 to 3 spectra from a few specimens, indicating localized areas rich in one of these elements. Low to questionable Pb peaks were present in at least one spectrum from each of 20 specimens. There is thus a non-homogeneous distribution of Ca and P and of many minor elements throughout the calculus.

[Study on mercury in dental calculus].

It has been reported that dental calculus contains trace elements of mercury besides lead, cadmium and zinc. The mercury is one of the hazardous metal elements from the environmental point of view. The purpose of this study was to clarify the mechanism of the accumulation of mercury in the dental calculus. The results were as follows: 1. The concentration of mercury was 1.6 ppm in the dental calculus collected from the subjects with no amalgam fillings. 2. The most of the mercury was found in the organic fraction of the dental calculus. 3. In the culture study of Bacterionema matruchotii in vitro, with the increase of Bacterionema matruchotii the uptake of mercury by the bacteria increased. And the maximum uptake of mercury was seen between 7 to 14 days of the culture period. 4. After 7 days of culture, the bacterial cells were destroyed into several fractions and the quantity of the mercury in the respective fractions was assayed. About 90% of mercury was found in the cell wall. From these results, it was suggested that the uptake of mercury by the bacteria was the cause of mercury accumulation in the dental calculus.