Human and mouse cementum proteins immunologically related to enamel proteins.

SDS-polyacrylamide gel electrophoresis, immunoblot and amino acid composition analyses were applied to human and mouse acellular cementum proteins immunologically related to enamelins and amelogenins. In this analysis, anti-mouse amelogenin, anti-human enamelin and synthetic peptide (e.g., -LPPHPGHPGYIC-) antibodies were shown to cross-react with tooth crown-derived enamelin with a molecular mass of 72,000 Da (72 kDa), amelogenins (26 kDa), and also to four human cementum proteins (72, 58, 50 and 26 kDa) and two mouse cementum proteins (72 and 26 kDa). Each of the antibodies recognized tooth root-derived cementum polypeptides which share one or more epitopes with tooth crown-derived enamel proteins. The molecular mass and isoelectric points for crown-derived and root-derived enamel-related proteins were similar. Analysis of human and mouse cementum proteins revealed a characteristic amino acid composition enriched in glutamyl, serine, glycine, alanine, proline, valine and leucine residues; compared to the major enamel protein amelogenin, cementum proteins were low in proline, histidine and methionine. The human and mouse putative intermediate cementum proteins appear to represent a distinct class of enamel-related proteins. Moreover, these results support the hypothesis that epithelial root sheath epithelia express several cementum proteins immunologically related to canonical enamel proteins.

Chemical and crystallographic events in the caries process.

The chemical and crystallographic events associated with the caries process can be described based on the results from the following studies: (a) effects of carbonate, magnesium, fluoride, and strontium on the physico-chemical properties--lattice parameters, crystallinity (crystal size and strain); dissolution properties of synthetic apatites; (b) factors influencing the in vitro formation and transformation of DCPD, OCP, AP (Ca-deficient apatites), FAP, beta-TCMP (Mg-substituted), and CaF2; and (c) studies on properties (crystallinity, composition, chemical, and thermal stabilities) of enamel, dentin, and bone. The dissolution of CO3-rich/Mg-rich/F-poor dental apatite crystals and re-precipitation of CO3-poor/Mg-poor/F-rich apatite in the presence of F- ions in solution contribute to a more acid-resistant surface layer of the caries lesion. Fluoride promotes the formation of less Ca-deficient and more stable apatite crystals. The presence of Ca, P, and F in solution inhibits dissolution of apatite more than does the presence of F alone. Low levels of F in solution promote the formation of (F, OH)-apatite, even under very acid conditions; an increase in F levels causes the formation of CaF2 at the expense of DCPD or apatite, especially in acid conditions. F in apatite and/or in solution suppresses extensive dissolution of dental apatite and enhances the formation of (F, OH)-apatite crystals which are more resistant against acid-dissolution than are F-free apatite crystals.

Shallow fluorine depth profiles of cementum in periodontal disease--a pilot study.

A nuclear resonant reaction depth profiling technique was used to analyze elemental fluorine distribution in the first 20 microns of human dental cementum. A pilot sample of six periodontally-involved teeth indicated greater levels of fluorine in exposed cementum (0.9 leads to 2.4%) compared to cementum apical to the zone of epithelial attachment (0.4 leads to 1.1%). Furthermore, the exposed cementum appeared to have fluorine levels within the surface 5 microns comparable to the hypermineralized layer previously reported by x-ray diffraction and microprobe techniques. The nuclear resonant reaction is a non-destructive technique which yields useful information of surface elemental distribution as a function of depth, and may be regarded as a potential means of analyzing changes in the inorganic constitution of cementum during various physico-chemical pre-treatments.

In vitro root caries progression measured by 125I absorptiometry: comparison with chemical analysis.

Radiation from a 125I source and a non-image-forming detector was used for non-destructive measurements of root caries progression. Blocks were cut parallel to the cementum surface of unexposed human roots. These blocks were then individually demineralized in under-saturated calcium phosphate solutions over an 84-hour period. In order for the in vitro root surface demineralization to be followed, the changes in transmission (delta T) through the blocks were measured, by 125I absorptiometry, eight times during the course of the experiment. Chemical analyses of the calcium output (delta Ca) from the blocks into the demineralizing solutions were also performed, and the rate of demineralization (Vdem) was calculated from these values. The precision of 125I absorptiometry was calculated from 176 duplicate transmission measurements, and the coefficient of variation was found to be 0.20%. The correlation coefficient between delta T and total delta Ca for each of 22 cementum/dentin blocks ranged between r = 0.934 and r = 0.998. The progression of root hard-tissue lesions observed by these two methods and by the calculated Vdem was found to be proportional to the square and cubic roots of time. The study shows that 125I absorptiometry can be used for continuous non-destructive measurements of root hard-tissue demineralization in vitro.

Bovine tooth-derived bone morphogenetic protein.

Eight groups of dental tissues were mechanically dissected from the mandibles of one-year-old steers; they were then defatted and decalcified in HCl. The noncollagenous proteins were extracted with various solvents from collections of tissue and bio-assayed for osteo-inductive activity. Collectively, the hard tissue (dentin, enamel, and cementum) noncollagenous proteins were fractionated by molecular sieve chromatography, hydroxyapatite affinity chromatography, and ion exchange chromatography. Osteo-inductive activity of each protein fraction was determined by implantation in the quadriceps muscle pouch of mice. The quantity of bone was measured by computerized image analysis. From 71% to 83% of 41 implants of dental hard tissues induced bone formation. The quantity of bone was greater from unerupted than from erupted teeth. Dental soft tissues that had no osteo-inductive activity were rich in a 14-kDa protein, presumably matrix gamma-carboxyglutamic acid-rich proteins. Proteins with Mr of from 15 to 28 kDa were associated with osteo-inductive activity. Components with Mr greater than 28 kDa had no activity. These observations suggest that bovine teeth have a selection of osteo-inductive proteins that is comparable in range of MW to bovine bone morphogenetic protein.

Mitogenic activity of cementum components to gingival fibroblasts.

Cementum forms the interface between root dentin and periodontal ligament through which periodontal connective tissue is attached to root surfaces. We have examined how cementum components influence the biological activities of gingival fibroblasts. Cementum was harvested from freshly extracted human teeth and extracted sequentially with 0.5 mol/L acetic acid, 4 mol/L guanidine-0.5 mol/L EDTA, and bacterial collagenase. The extracts were concentrated and analyzed for mitogenic activity to human gingival fibroblasts. DNA synthesis was assayed by measurement of [3H]thymidine incorporation by quiescent fibroblasts activated to divide, and cell growth was determined by the counting of cells over a 10-day period. Results showed that extracts of cementum stimulated quiescent gingival fibroblasts to synthesize DNA and grow. The stimulation was dose-dependent, and most of the stimulatory activity was extracted by acid. Addition of small quantities of serum potentiated the mitogenic activity to levels greater than those of control cultures containing 10% fetal calf serum. The mitogenic activity was heat-stable, but it was destroyed by trypsin. Neither platelet-derived growth factor (PDGF) nor epidermal growth factor (EGF) was detectable in the cementum extract, and extracts of human dentin and skin contained very little mitogenic activity. We conclude that cementum contains substances capable of regulating the growth of gingival fibroblasts, and that these substances may play an important role in gingival connective tissue formation and regeneration.

Mucopolysaccharidase activity and glycosaminoglycan content in traumatized resorbing deciduous teeth.

The periodontal ligaments from traumatized deciduous teeth, while undergoing rapid resorption, were analyzed biochemically for mucopolysaccharidase activity and for total glycosaminoglycan content of dentin and cementum. Enzyme activity was present only in resorbing teeth. A concomitant 65 percent decrease in glycosaminoglycans from these teeth occurred as well.

Periodontally diseased vs. normal roots as evaluated by scanning electron microscopy and electron probe analysis.

A scanning electron microscope and electron probe study was carried out to compare root structure from deep within periodontal pockets with roots exhibiting no periodontal disease. To eliminate the possibility of extraneous ion introduction or deletion, no attempt was made to subject the roots to fixation, embedding, or dehydration prior to sectioning and viewing in the electron microscope. Mineral content and concentration were determined with an electron probe on two specimens per tooth. On one specimen, only the external cemental surface was analyzed. On an adjacent cross section, readings were taken from the surface and at incremental depths into the root. A nonparametric statistical analysis compared diseased with nondiseased roots. The following conclusions can be drawn from the study: (1) Consistent and repeatable qualitative electron probe analyses can be performed on human teeth with minimal specimen preparation. This gives a more accurate assessment, since the integrity of the crystalline structure is not disrupted. (2) Minerals consistently found were P, Ca, Cu, Zn, Mg and Na. They were in similar concentrations throughout the area analyzed. (3) Mg and Cu showed higher values in the nondiseased teeth. (4) There were no differences in concentrations for Ca, P, Zn, and Na between roots exposed to a periodontal pocket and nondiseased roots.

The effects of age and fluoride exposure on fluoride, citrate and carbonate content of human cementum.

A study was conducted to determine the values of several chemical components of dental cementum. Extracted teeth from continuous residents of low, optimal, and high natural fluoride areas were selected to determine the effects of fluoride exposure and age on the fluoride, citrate and carbonate content of cervical and apical areas of sound and periodontally diseased human cementum. 1. For normal cementum the mean fluoride content of all 18 groups was 0.443 plus or minus 0.04%on an ash basis and 0.253 plus or minus 0.02% on a dry weight basis; the mean citrate content was 1.52 plus or minus 0.10% on an ash basis and 0.86 plus or minus 0.06% on a dry weight basis; the mean carbonate content was 4.95 plus or minus 0.39% on an ash basis and 2.79 plus or minus 0.22% on a dry weight basis. 2. For diseased cementum the mean fluoride content of all 12 groups was 0.575 plus or minus 0.03% on an ash basis and 0.342 plus or minus 0.02% on a dry weight basis; the mean citrate content was 1.19 plus or minus 0.07% on an ash basis and 0.71 plus or minus 0.05% on a dry weight basis; the mean carbonate content was 5.95 plus or minus 0.47% on an ash basis and 3.50 plus or minus 0.28% on a dry weight basis. 3. There is a general increment in fluoride content of normal cervical and apical cementum, both with age and fluoride exposure. For diseased cementum this held true for fluoride exposure but not age. 4. The mean fluoride content of cervical cementum is greater than that of apical cementum for both normal and diseased groups. For citrate and carbonate no definite statistical differences were noted between cervical and apical areas. 5. The diseased cementum has a significantly higher mean fluoride content, a significantly lower citrate content, and a slightly, but not statistically significant, higher carbonate content than normal cementum. 6. Unlike bone, no inverse fluoride/citrate or fluoride/carbonate relationship was observed. 7. For both normal and diseased groups the carbonate content of cementum of individuals over age 40 tended to be lower than for individuals 20-40 years of age.

The hypermineralization of diseased root surfaces.

Root surfaces which have lost their attachment due to chronic inflammatory periodontal disease present significant increases in calcium, magnesium, phosphorus, and fluoride. The clinical significance of this effect is not known in regards to wound healing, but it may be helpful in control of cervical sensitivity.

Fluoride distribution and histological structure of human cementum.

Thirty-one teeth taken post-mortem from 10 subjects aged from 40 to 66 years were studied. A close relationship was found between fluoride (F) distribution and histological structure. Although, as in all mineralized tissues, F concentrations tended to be highest towards the external surface, individual patterns of F distribution also seemed to reflect the histological pattern, especially the distribution of cellular or acellular cementum. In general, F concentrations were high in acellular and low in cellular cementum.

External radiolabelling of components of pellicle on human enamel and cementum.

Enamel and cementum pellicles form by different adsorption of salivary and serum components to the tooth surface. The authors compared the constituents of surface pellicle formed on human enamel and cementum under three conditions: (1) natural pellicle, present on extracted teeth, which was formed by prolonged exposure to human salivary and serum components in vivo; (2) short-term in-vivo pellicle, formed by exposing enamel and cementum slabs to the oral environment for 0-60 min; (3) in-vivo pellicle, formed by incubating enamel and cementum slabs in a 1:1 mixture of parotid and submandibular/sublingual saliva for 0-60 min. Pellicle composition was characterized by external radiolabelling techniques specific for exposed carbohydrate (sialic acid and galactose) and amino-acid (tyrosine) residues. There were differences between cementum and enamel in the electrophoretic profiles of natural-pellicle components; notably, a major 180 kda 3H-labelled sialoglycoprotein, unique to the cementum pellicle, had the same electrophoretic mobility as the low-molecular-weight mucin from human submandibular/sublingual saliva. After alkaline-borohydride treatment, 3H-labelled natural-pellicle oligosaccharides chromatographed in the di- to tetrasaccharide region of a Bio-Gel P-2 column. The most prominently labelled components of short-term enamel and cementum pellicles in vivo and in vitro had the same electrophoretic mobility as the low-molecular-weight salivary mucin. The pellicle components formed in vitro, unlike those formed for the same period of time in vivo, were rapidly desorbed from the cementum, but not from the enamel surface. We conclude that: (1) external labelling techniques are useful for obtaining a profile of pellicle components; (2) submandibular/salivary mucins are major constituents of salivary pellicles on tooth surfaces; (3) glycoproteins that carry low-molecular-weight, sialic-acid-containing saccharides are important determinants of pellicle surface properties [corrected].

The distribution and quantitation of cementum-bound lipopolysaccharide on periodontally diseased root surfaces of human teeth.

The aim of this study was to estimate the concentration of cementum-bound LPS on a group of 12 teeth that had been extracted because of periodontitis. LPS on scaled root surfaces was labelled by immunogold/silver staining. The concentrations of LPS were estimated by quantifying the amount of bound silver label, using X-ray microanalysis in areas free of plaque or calculus. These were compared against standards of known LPS concentration, which were separately prepared for each sample. Cementum-bound LPS was detected at concentrations of up to 2 EU/mm2 of affected root surface. However, most of the root surfaces had considerably lower concentrations than this, the mean of all samples never exceeding 0.7 EU/mm2. LPS concentrations were highest on cementum towards the apical regions of the affected pocket. These findings confirm that cementum-bound LPS is only present in low concentrations on affected teeth, and suggest that the clinical significance of cementum-associated LPS may have been over-estimated in the past. The demonstration of LPS appears to be more important as an indicator of retained bacteria and calculus than of cementum-bound LPS per se.

Distribution of fluoride in human cementum.

Fluoride and phosphorus concentrations were determined in layers of cementum and dentine serially-abraded from the root surface, passing through the cementum-dentine junction and into the underlying dentine, using silicon carbide-impregnated film. The concentrations of F in the cementum mineral were variable but consistently maximal at or near to the external surface of the root and tending to fall towards the interior and across the cementum-dentine junction into the underlying dentine. The F content in the cementum tended to increase with age.

The amino-acid composition of the non-collagenous organic matrix of human cementum.

Human cementum was demineralized and exhaustively extracted with EDTA and then digested with collagenase. The insoluble residue after digestion was extracted successively with 8M urea and with 8M urea containing 0.1M mercaptoethanol. The non-collagenous fraction accounted for a larger proportion of the total organic matrix than previously found in bone and dentine, largely due to the presence of more collagenase-insoluble material. Fractionation of the EDTA-soluble material resulted in less-acidic fractions, showing similarities to the corresponding fractions of bone and dentine, and anionic fractions with lower levels of acidic amino acids than those from other hard tissues. Fractions obtained from the soluble collagenase-released material after ion-exchange chromatography and gel filtration, although more heterogeneous than those of bone and dentine, showed many similarities, thus confirming the close homology within this fraction from the various hard tissues. The insoluble residue after collagenase digestion appeared to be of the acid-structural protein type found also in bone, dentine and a wide range of connective tissues.

Phosphoprotein extraction from the dentine/cementum complex of human tooth roots.

Root shards were placed in dialysis tubing and demineralized to completion in either 10% disodium EDTA, pH 7.4, 0.6 M HCl, 0.1 M HCl, 0.5 M acetic or 75 mM-25 mM lactic-acetic acids. The demineralized shards were then re-extracted with 0.05 M tris-HCl, 1.0 M NaCl. DEAE chromatography revealed that the major peak of the 0.6 M CHl and EDTA extracts contained organic phosphorus, whereas much less organic phosphorus was found in the major peak of the 0.1 M HCl extract. Analysis of the re-extracts gave a pattern opposite to that obtained from the initial extractions. Measurements of protein and organic phosphorus released during extraction and re-extraction confirmed these results. Staining of SDS-PAGE gels for phosphoprotein with Stains-All resulted in a blue smear in fractions containing organic phosphorus. Thus the extraction of phosphoproteins from human tooth roots differed depending upon the demineralizing conditions. This ability to remove phosphoprotein differentially will allow further investigation of the role of phosphoprotein in mineralization and remineralization.

[Amount of mineralized tissue removed by root planing]. / Quantità di tessuto mineralizzato rimosso dalla levigatura radicolare.

The Author's aim was to determine the amount of mineralized tissues removed during root planing conducted by means of a curette, using a profilometer. Records were kept at time 0 and after 4 cycles of 5 strokes each. Mean values of final records show that the average of tissue removal, expressed in microns, was greater than the mean thickness of cementum in the instrumented areas.

[Determination of calcium and trace elements in hard tissues of the healthy tooth by neutron activation analysis and statistical data processing]. / Determinazione del Ca e di elementi in tracce nei tessuti duri del dente sano mediante analisi per attivazione neutronica e trattamento statistico dei dati.

Instrumental neutron activation analysis has been used to determine quantitatively the content of certain trace elements forming the healthy tooth in a sample of 31 teeth extracted for orthodontic or periodontal reasons.

[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.

[Electron microscopic research on the structures of exposed cementum]. / Elektronenmikroskopische Untersuchungen über die Struktur des freiliegenden Zementes.

In this study the ultrastructure of exposed cementum just below the cemento-enamel junction was investigated. In a surface layer of exposed cementum measuring up to 4 microns in depth, newly formed crystallites were observed. These crystallites were 660-1800 A long and 130-260 A thick. They were thicker than those in the deeper zones of exposed cementum and in sound cementum. Electron diffraction studies showed that these crystallites were hydroxylapatite. In the zone of new crystallites at the tooth surface the crossbanding of collagen fibers was not discernible. At the tooth surface carious changes were seen only in minor areas. Another finding was the formation of large crystallites. They were found to have the following dimensions: length 3000 A, thickness 550 A.