The proteoglycans of human cementum: immunohistochemical localization in healthy, periodontally involved and ageing teeth

Cementum is believed to play a regulatory role in periodontal regeneration through a variety of macromolecules present in its extracellular matrix (ECM), among which are the proteoglycans (PG). The PG of human cementum have not been fully characterized. This study has used a standard indirect immunoperoxidase technique to investigate the presence and distribution of PG species within the ECM of human cementum. Freshly extracted human permanent teeth were separated into 8 age groups; each group was subdivided to include healthy and periodontally involved teeth, which were then fixed, demineralized and wax-embedded. Sections were incubated with polyclonal antibodies recognizing protein core epitopes in the large chondroitin sulphate PG versican and the small interstitial PG decorin, biglycan, fibromodulin and lumican. Immunoreactivity to versican, decorin, biglycan and lumican was evident at the borders and lumina of a proportion of lacunae and canaliculi surrounding cementocytes in cellular cementum, as well as on inserted periodontal ligament (PDL) fibres. Biglycan was also present along incremental lines in cellular cementum, whereas staining for fibromodulin was negative. In acellular cementum, no immunoreactivity was evident with any of the antibodies used except on inserted PDL fibres. These results indicate that versican, decorin, biglycan and lumican are components of the ECM of cellular, but not of acellular cementum. Neither age nor periodontal diseases appear to qualitatively influence the PG population of cementum. The distribution of PG epitopes around a proportion of cementocytes suggests the existence of different cementocyte subpopulations, or a differential response of these cells to yet undefined stimuli.     

Histological assessment of root cementum at periodontally healthy and diseased human teeth

This study aimed to investigate and compare the lipid and polysaccharide content of the cemental surfaces of healthy and periodontally-involved teeth. Thirty periodontally-involved single-rooted teeth from fifteen patients with localized juvenile, adult and rapidly progressive periodontitis were included in the experimental group and 5 healthy teeth were assessed in the control group. Frozen serial sections were obtained and stained with hematoxylin-eosin for morphological assessment. Oil-Red-O and Alcian Blue-Periodic Acid Schiff stains were used to evaluate the presence of lipids, neutral and acidic polysaccharides using light microscopy. It was found that with hematoxylin-eosin staining in the experimental group, both the involved and uninvolved cementum surfaces of teeth, which belong to all periodontitis groups, showed generally irregular surfaces that contain some resorption areas. Alcian Blue-Periodic Acid Schiff positive staining was observed only superficially and at the areas associated with microbial dental plaque. However, Oil-Red-O staining was positive only superficially at 5 teeth that belonged to localized juvenile and rapidly progressive periodontitis groups. Apparent lipopolysaccharide staining into cementum was not seen in any of the diseased teeth. The results presented here suggest that endotoxin was only localized in superficial layers and associated with only microbial colonization.     

Subgingival debridement of root surfaces with a micro-brush: macroscopic and ultrastructural assessment

AIM: The aim of this study was to assess the use of a micro-brush to remove plaque deposits from subgingival, periodontally involved root surfaces in vivo. METHODS: 30 periodontally involved teeth requiring extraction for periodontal or prosthetic reasons in 26 adult patients were utilised. For inclusion, teeth had to display at least 30% bone loss radiographically. Following the establishment of local anaesthesia, grooves were cut on the proximal root surface adjacent to the gingival margin at the line angles. For each tooth, 1 proximal root surface was rubbed with the micro-brush for 2 min to the depth of the pocket whilst the other root surface acted as an undebrided control. The teeth were then extracted, rinsed in 0.85% NaCl, stained with 2% erythrosine solution and photographed. The amount of erythrosine staining on each subgingival, periodontally involved root surface was assessed by tracing the areas of stain on a colour photograph and scanning the tracings into a computerised image tracing program. RESULTS: Results were expressed as the % of the periodontally involved root-surface area that exhibited staining. Stained areas were further examined with the scanning electron microscope (SEM). The undebrided root surfaces each displayed 100% staining. The debrided surfaces (with probing pocket depths of 4-10 mm) displayed mean staining of 16.1% (SD +/-7.1%) of the proximal surface area. SEM assessment showed that undebrided root surfaces were covered with thick deposits of bacteria. On debrided surfaces, stain-free areas were free of plaque whilst areas of faint staining exhibited either no plaque, calculus deposits or scanty, isolated islands of bacteria. Bacteria had been partially removed from the surface of calculus in some areas. CONCLUSIONS: The findings indicate that subgingival debridement with a micro-brush is effective in removing plaque deposits from periodontally involved root surfaces.     

牙周病病变牙骨质微区成分的电子探针分析

对２１个牙周炎患牙病变牙骨质的微区无机成分作显微分析，结果表明：Ｃａ、Ｍｇ、Ｃｌ、Ｃｕ元素在龈上、袋内和骨内３平面含量有统计学差异。而Ａｌ、Ｓｉ、Ｐ、Ｓ、Ｋ、Ｚｎ诸元素在３平面病变牙骨质中含无差异。     

牙骨质的研究进展

本文综述了牙骨质分型，成分，发育的研究成果，讨论了上皮根鞘在成牙骨质细胞分化，牙骨形成中的可能作用，介绍了成牙骨质细胞模型的研究进展。     

Human root caries: histopathology of initial lesions in cementum and dentin

The histopathology of human root caries was examined in extracted teeth by different optical methods. The present part of the study details the sequential stages of initial caries in both cementum and peripheral dentin. Significant differences are shown between the mechanisms operating on the various dental hard tissues during development of caries. Histologically distinguishable reaction patterns depended on both the degree of the cariogenic challenge and the respective structural features of cementum and peripheral dentin. Earliest lesions, histologically visible as small clefts traversing cementum and extending into peripheral dentin, were clinically not detectable. Cementum was stepwise destroyed until peripheral dentin became exposed. The exposed peripheral dentin was sclerosed and tubule-free. Demineralization of dentin preceded the degradation of the organic matrix. Frequently, a hypermineralized layer occurred in both cementum and exposed dentin. Its localization was not identical with the anatomical surface. Initial penetration of bacteria into peripheral dentin occurred along small clefts. Breakdown of the organic matrix was the final step in the destructive phase of the carious process.     

Citric acid treatment of periodontitis-affected cementum

Previous studies have described an inconsistent histological occurrence of a zone of surface demineralization on periodontitis-affected cementum following treatment with citric acid, and a lack of connective tissue attachment to the latter surfaces. In view of these findings, the purpose of the present study was to use scanning electron microscopy to examine the surface morphology of cementum from normal and periodontitis-affected root surfaces following citric acid treatment for differences in the effects of the demineralizing solution on these surfaces. Cementum surfaces were derived from the roots of extracted human teeth from areas beneath attached periodontal ligament fibers (normal) and calculus deposits (periodontitis-affected). 5 specimens were evaluated in both groups. Periodontal ligament fibers were removed from normal root surfaces with a curette, and calculus deposits were removed from periodontitis-affected root surfaces using an ultrasonic scaler. The resultant 5 specimens in each group were then sectioned in half, one-half serving as the untreated control and the other as the experimental, citric acid treated specimen. Experimental specimens were immersed in a saturated solution of citric acid, pH 1 for 3 min and then rinsed in tap water. Both control and experimental specimens were dehydrated in ethanol, critical-point dried, sputter-coated with gold and examined in the scanning electron microscope for morphological characteristics. Citric acid treatment of cementum from normal root surfaces produced an undulating, markedly fibrillar surface morphology which is consistent with the exposure of a fibrillar, collagen substrate. Periodontitis-affected cementum, however, was not appreciably altered in appearance by the citric acid treatment, having only a faint mat-like surface texture. (ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of two different approaches for root decontamination on new cementum formation following guided tissue regeneration: a histomorphometric study in dogs

BACKGROUND AND OBJECTIVE: The aim of the present study was to evaluate comparatively the effect of two different approaches for root decontamination on new cementum formation following guided tissue regeneration (GTR). MATERIAL AND METHODS: Nine mongrel dogs were used to obtain bilateral chronic class III furcation defects by placing cotton ligatures around both third mandibular premolars. The teeth were randomly assigned to receive one of the following treatments: scaling and root planing, by means of hand and rotatory instruments, in order to remove soft and hard deposits as well as all root cementum (group A); or removal of only soft microbial deposits, by polishing the root surface with rubber cups and polishing paste, aiming for maximum root cementum preservation (group B). Both groups were treated with GTR, with the use of resorbable polyglycolic-lactic acid membranes (RESOLUT XT). RESULTS: Four months later, data analysis showed that a superior length (mm) (3.59 +/- 1.67 and 6.20 +/- 2.26 for groups A and B, respectively; p = 0.004) and a thicker layer (microm) (18.89 +/- 9.47 and 52.29 +/- 22.48 for groups A and B, respectively; p = 0.001) of new cementum was achieved by keeping the root cementum in place during root decontamination (group B). Regardless of the treatment modality, the new cementum was predominantly of a reparative, cellular extrinsic and intrinsic fiber type. CONCLUSION: Within the limits of the present study, it may be concluded that root cementum preservation may affect the new cementum formation following GTR in class III furcation defects, and the treatment modality did not influence the type of newly formed cementum.     

牙周炎患者前牙区压低后骨缺损形态的初步研究

目的本研究通过正畸压低排齐牙周炎患者伸长、移位的前牙,探讨正畸压低后前牙区的骨缺损形态。方法选取11例牙周炎患者的20颗伸长、移位的患牙,治疗前牙槽骨形态均为水平型骨吸收,正畸压低排齐患牙,采用Morita CT对压低排齐后的骨缺损形态进行评价。结果2名患者的近远中侧均出现了角型吸收,其余患者个别位点出现了角型吸收。结论压低单颗前牙在近、远中侧比较容易出现角型吸收;同时压低2颗或以上的牙齿,压低后一般仍为水平型吸收。     

Role of "diseased" root cementum in healing following treatment of periodontal disease

This clinical trial was undertaken to examine whether root debridement in the treatment of periodontal disease must include the removal of the exposed cementum in order to achieve periodontal health. The study included 11 adult patients with moderate to advanced periodontal disease. In a split-mouth design, the dentition of each patient was by random selection divided into test- and control quadrants comprising the incisors, canines and premolars. Following a baseline examination, all patients were given a case presentation and a detailed instruction in self-performed oral hygiene measures. The patients were then subjected to periodontal surgery. Following reverse bevel incisions, buccal and lingual mucoperiosteal flaps were elevated and all granulation tissue was removed. In 2 jaw quadrants (control quadrants) in each patient, the denuded root surfaces were carefully scaled and planed in order to remove soft and hard deposits as well as all cementum, using hand instruments and flame-formed diamond stones. In the contralateral quadrants (test quadrants) the roots were not scaled and planed but soft microbial deposits were removed by polishing the root surfaces with the but soft microbial deposits were removed by polishing the root surfaces with the use of rubber cups, interdental rubber tips and a polishing paste. Calculus in the test quadrants was removed by the use of a curette, but precaution was taken to avoid the removal of cementum. The flaps were repositioned to their original level and sutured. The patients were following active treatment enrolled in a supervised maintenance care program including "professional tooth cleaning" once every 2 weeks for a 3-month period.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of the necrotic periodontal membrane in cementum resorption and ankylosis

Abstract Teeth replanted with non-vital periodontal membranes demonstrate a high incidence of root resorption and ankylosis. It has been suggested that necrotic periodontal membrane remnants actively stimulate resorption of the resistant cementum layer. The aim of this study was to examine resorption and ankylosis patterns following replantation of teeth with chemically denuded root surfaces and, by extrapolation from these data, to suggest a role for the necrotic periodontal membrane in resorption and ankylosis. Monkey incisors were replanted after endodontic therapy and immersion in 10% sodium hypochlorite. Teeth were either examined with scanning electron microscopy at intervals from 1 day to 8 wk, or subjected to light microscopic examination, using a morphometrical evaluation technique, at 8 wk post-replantation. Only a few macrophage-like cells, in relation to shallow resorption lacunae, were observed by 8 wk. Histologically, the alveolar bone had approached an apparently intact cementum surface in 93% of the morphometrically recorded points. This bone appeared to lie in close approximation to the cementum surface. Denuding the root surface of periodontal membrane prior to replantation demonstrated the resistance of the cementum to colonization and resorption in the absence of stimulation from necrotic periodontal membrane remnants. Furthermore, it revealed that bone replacing the periodontal membrane space grew from the alveolus towards the cementum, to which it appeared unable to fuse due to the absence of significant resorption. Thus, removal of a non-vital periodontal membrane may result in slower destruction of tooth substance following replantation of teeth with severely damaged periodontal membranes.     

牙囊和上皮根鞘细胞成无细胞牙骨质的机制

无细胞牙骨质是锚定牙周纤维和牙根的重要组织结构,牙囊细胞（DFC）通过自身分化和上皮根鞘（ERS）通过上皮-间质转化（EMT）形成的成牙骨质细胞参与无细胞牙骨质形成。牙囊细胞体外移植后可形成纤维样和牙骨质样组织,而牙乳头和上皮根鞘可以诱导牙囊细胞从基因及其蛋白质水平高表达碱性磷酸酶、骨涎蛋白等无细胞牙骨质相关标志物。其中钙离子、骨形态发生蛋白、Wnt／β-连环蛋白通路等目前被认为是介导牙囊细胞成牙骨质分化的信号转导通路。目前发现,调控无机磷酸盐胞内外浓度的转运蛋白对无细胞牙骨质形成调节的敏感性更高。ERS亦可通过EMT形成间质细胞来参与牙周组织的发生。钙结合蛋白D28k、末端较小的同源异形盒-2等在无细胞牙骨质、ERS以及牙囊细胞表达差异都说明了ERS具有成牙骨质细胞特性。在此过程中,TGFβ激活下游蜗牛蛋白后,通过磷脂酰肌醇-3-激酶和蛋白激酶B信号转导通路来介导ERS的无细胞牙骨质分化过程。     

Alkaline phosphatase activity in human periodontal ligament: age effect and relation to cementum growth rate

Recently, a relationship was demonstrated between the thickness of the cementum layer in rat molars and the activity of alkaline phosphatase (ALP) in the adjoining periodontal ligament (PDL). It was the aim of the present study to investigate whether such a relationship also exists in the periodontium of man. Healthy deciduous and permanent teeth free from periodontitis were obtained from 74 patients, varying in age from 3 to 78 yr, and their PDL dissected from the middle one-third of the roots. ALP activity was measured in PDL extracts and expressed per hydroxyproline content. It was shown that ALP activity was relatively high in children. After puberty its concentration decreased to level off at about half the concentration found in the younger age groups. The activity of the enzyme in the PDL correlated positively with the yearly cementum thickness increment as calculated from data published previously.     

Cell attachment activity of cementum: bone sialoprotein _ identified in cementum

Considerable research effort has been directed at preparing root surfaces in a fashion that would promote cell attachment leading to periodontal regeneration; however, no methods have proven to be clinically predictable. Identification of attachment protein(s) associated with the root surface matrix of cementum may prove valuable for developing effective clinical treatments. In this study cementum proteins were extracted from bovine and human teeth by sequential chaotropic extraction using guanidine followed by guanidine/EDTA. The guanidine/EDTA extract, but not guanidine extract, was found to promote attachment of fibroblasts. This attachment activity was inhibitable with synthetic peptide containing the attachment sequence arginine-glycine-aspartic acid (RGD). Fractionation of the guanidine/EDTA extract revealed several fractions with attachment activity. Immunoblot analysis demonstrated that two of these fractions contain the bone-associated RGD containing attachment protein, bone sialoprotein-II (BSP-II). In addition, attachment activity was also noted in other fractions that could not be attributed to BSP-II or fibronectin. These studies indicate that a component of the attachment activity of cementum is likely to be due to BSP-II and that cementum contains additional, as yet undetermined, attachment proteins.     

Lipopolysaccharide (endotoxin) from individual periodontally involved teeth

The amount of lipopolysaccharide (LPS) in the root surface-associated material from individual periodontally-involved teeth has been determined. LPS was found in the surface material from all of the teeth and the amount present ranged from 19-394 ng/tooth. No significant correlation was found between the amount of LPS extracted from a particular tooth and the mean pocket depth associated with the tooth. However, a weak correlation (rs = +0.461, 0.05 greater than p greater than 0.01) was found between the amount of LPS and the % loss of attachment.     

Evidence for rapid multipolar and slow unipolar production of human cellular and acellular cementum matrix with intrinsic fibers

The genesis of root cementum has been studied infrequently in animal models, e.g., in mice, rats and dogs, but rarely in the human. The present study was based on 8 premolars (4 maxillary and 4 mandibular, 7 first and 1 second) selected from a large collection of freshly extracted human teeth. All teeth were free of disease and presented with roots developed to about 50-80% of their length. After decalcification in EDTA, the apical half of the roots was divided axially into mesial and distal portions. The latter were subdivided into 4 slices cut in the corono-apical direction. These slices were Epon-embedded and cut for examination in the light- and transmission electron microscope. It was found that 2 basically different modes of cementum matrix production occurred at or near the advancing root edge. These 2 modes, i.e., the multipolar versus unipolar matrix production, resulted in either cellular (CIFC) or acellular intrinsic fibre cementum (AIFC). Both varieties did not contain fibres of Sharpey and were restricted to regions of the root usually covered with cellular mixed stratified cementum (CMSC). By comparison with recently published data on the rate of cementum apposition, it is suggested that the multipolar mode is a rapid form, whereas the unipolar mode is a slow-rate form of producing intrinsic fibre cementum.     

An assessment of patients with periodontally involved migrated incisors

Thirty patients with periodontal disease whose incisors had migrated were examined in order to see in what way they differed from patients with periodontal disease whose incisors had not migrated. In the patients with migrated incisors there was a higher incidence of Class 2 skeletal pattern and a far greater amount of bone loss. This group also had an increased overjet and the angulation of the lower incisors to the mandibular plane was greater as compared with patients in whom the incisors had not migrated.