Effects of autologous platelet lysates on ceramic particle resorption and new bone formation in critical size defects: the role of anatomical sites.

This study investigated the effects of rabbit autologous platelet lysates (APL) on the performance of fillers consisting of calcium carbonate ceramic particles (CP) pertinent to new bone formation and repair. Critical-size defects in rabbit femurs and calvaria were filled with CP alone, CP plus APL, and CP plus APL with or without thrombin (THR). After 6 weeks, resorption of CP occurred under all conditions tested in the present study. Compared with respective CP alone controls, addition of APL resulted in significantly higher ceramic resorption, as evidenced by decreased ceramic particle diameter (p < 0.01) and number (p < 0.01) at both defect sites. The presence of THR prevented reduction of both CP diameter and number in the femoral defect sites. Addition of APL to the CP resulted in a significant (p < 0.03) decrease in new bone area at the calvarial sites, but not at the femoral sites; moreover, when THR was added to the CP plus APL fillers, bone formation in the femoral defects was significantly (p < 0.05) reduced. In addition to differences in the respective anatomical and cellular milieu, the biochemical events induced by mechanical loading at the femurs may explain the reduced ceramic particle resorption as well as the enhanced new bone formation when compared with the results obtained at the calvarial defect sites.

Penetrating the plaque biofilm: impact of essential oil mouthwash.

The interaction between saliva-coated tooth surfaces and pathogenic bacteria is partly governed by electrostatic and hydrophobic interactions, providing a solid rationale for using chemical agents as part of a plaque-control routine. Chlorhexidine works in several ways. For example, it binds to salivary mucins on the bacterial cell membrane, and penetrates the plaque biofilm. Essential oil (EO) mouthwashes kill micro-organisms by disrupting their cell walls and inhibiting their enzymic activity. They prevent bacterial aggregation, slow multiplication and extract endotoxins. Recent studies have shown that bacterial phenotypes are altered when organisms change from a planktonic to a sessile state. This suggests that an effective mouthwash must also penetrate the plaque biofilm. Two studies have demonstrated the ability of an EO mouthwash to penetrate the plaque biofilm.

Bone formation with discs or particles of natural coral skeleton plus polyglactin 910 mesh: histologic evaluation in rat calvaria.

Several procedures have been used to regenerate localized bone defects around dental implants or to increase bone volume at an implant site, including bone grafting, placement of barrier membranes, and use of bone graft substitutes. This study sought to determine whether the bone graft substitute natural coral skeleton (NCS), with or without a protective polymer mesh, enhances bone formation in rat critical size craniotomy defects. The control group (1) had unfilled defects, while the defects in the four experimental groups (six rats each) were treated with: (2) an NCS disc of the size of the defect; (3) NCS granules; (4) NCS granules covered by a polyglactin 910 mesh; and (5) polyglactin 910 mesh alone. Undecalcified histologic sections were assessed by histomorphometric measurements 28 days later. The three NCS groups showed improved bone formation, which was statistically significant in groups (2) (NCS disc) and (4) (NCS granules covered by polyglactin 910 mesh). Group 4 had more bone formation than all the other groups. Polyglactin 910 mesh alone (group 5) produced no greater bone formation than the unfilled control. It is concluded that the bone formation obtained with NCS granules is enhanced when the particles are retained at the site of the defect with a protective mesh.

In vitro induction of osteogenic differentiation from non-osteogenic mesenchymal cells.

The process of ectopic bone formation suggests that extraskeletal cells are capable of osteogenesis. Alkaline phosphatase (ALP) activity is considered to be an early marker of osteogenic differentiation. This study determined whether cells from the rabbit dermis, striated muscle and extramedullary adipose tissue could undergo osteogenic differentiation in vitro. The cells were cultured with two osteoregulators, recombinant human bone morphogenetic protein 2 (rhBMP2) and dexamethasone. Incubation of extramedullary adipose cells with a combination of rhBMP2 and dexamethasone resulted in an increase in their ALP activity. The results suggest that extramedullary adipocytic cells may undergo osteogenic differentiation.

In situ hybridization study of cytokeratin 4, 13, 16 and 19 mRNAs in human developing junctional epithelium.

Cytokeratins (CKs) are now considered to be reliable markers for following the development and differentiation of epithelial tissue. We have investigated the pathway of differentiation in human developing junctional epithelium using monoclonal antibodies and two-dimensional gel electrophoresis of microdissected tissue to identify CK 19, CK 16, CK 14, CK 13, CK 6, CK 5, CK 4 in the junctional epithelium (JE) over partially erupted human teeth. The CK profile was similar to that of developing oral epithelia, suggesting that the junctional epithelium in teeth during eruption is of odontogenic origin. The present study used in situ hybridization to determine the distribution of the mRNAs of CKs 19, 16, 13 and 4 in human developing junctional epithelium and to examine the correlation between mRNAs and their encoded proteins. CK 19 mRNA was abundant in the basal cell layers of the primary junctional epithelium (PJE) but less concentrated in the suprabasal layers. CK16, 13 and 4 mRNAs were abundant in the basal cell layers of the PJE. The parabasal cell layers reacted intensely to the cRNA probe complementary to CK16 mRNA, as were the reactions in the suprabasal cell layers of the PJE for the CK 13 and 4 probes. Our results demonstrate that the PJE express the genes encoding for CKs 16 and 4 that have been revealed previously only by electrophoresis. They therefore confirm that the PJE is a well-differentiated stratified epithelium with a complex unique phenotype that produces CKs specific for basal cells (CK 19), CKs associated with hyperproliferation (CK 16), and finally those associated with stratification (CKs 4 and 13). Only synthesis of CK 19 protein and mRNA are strictly parallel. CKs 4 and 13 mRNAs are present in basal and suprasal cells, while their encoded proteins were not, except for CK 13 in suprabasal cell layers of PJE, where the amount of its mRNAs was coincident with the expression of the protein.

Digital image ratio: a new radiographic method for quantifying changes in alveolar bone. Part II: Clinical application.

As reported in a previous paper (1) we have developed a new technique, Digital Image Ratio (DIR), which theoretically avoids some of the drawbacks of quantitative digital substraction radiography. DIR allows the direct computation and visualization of bone-mass-ratio changes. This second paper describes the use of DIR analysis to examine 20 sites in 8 patients undergoing regenerative periodontal therapy. Standardized reproducible radiographs of these 20 sites were taken before and 12 months after surgery. Ten experimental sites were treated with bone graft substitutes (natural coral or natural coral+collagen), and 10 control sites by debridement alone. None of the experimental sites had a density ratio below 1, where 1 indicates no change. The error was +/- 0.07 (0.93-1.07). The experimental sites showed an 18% mean increase in bone density (1.18), which increased to 23% (1.23) for sites filled with natural coral alone. All the control sites had values close to 1.00 (1.00 +/- 0.07) except for 3 sites, which showed a 9-15% loss of bone density. It is thus possible to compare and quantify the changes in experimental and control sites in the same patient using the percentage gain or loss of bone density. This demonstrates that DIR is suitable for clinical applications, and can be used in clinical analysis when bone changes are expected.

Treatment of interproximal angular defects by guided tissue regeneration: 1 year follow-up.

The periodontal regeneration of interproximal bone defects of the posterior teeth produced by guided tissue regeneration (GTR), with expanded Polytetrafluoroethylene barrier membranes and conventional therapy, was clinically evaluated in 20 intrabony periodontal defects in 10 patients. The material included the presence of at least two proximal angular lesions for the same patient, probing pocket depth > or = 6 mm, bone defect depth > or = 3 mm, and 2-wall defects with crestal involvement relative to the tooth circumference ranging from 90 to 270 degrees. Healing was clinically evaluated by surgical re-entry of GTR-treated sites (10 sites) and debridement only sites (10 sites) 1 year after initial surgery following a strict plaque control regimen. A significant correlation was observed between probing depth reduction, attachment gain and defect depth (test sites); there was increased bone fill in GTR-treated lesions of 2.95 +/- 1.3 mm corresponding to a 69.4% improvement compared to control sites, and 1.3 +/- 1.0 mm corresponding to a 32% improvement (P < 0.0039). The results demonstrated that bone regeneration is highly reliable, as compared to conventional therapy, in cases of severe periodontal bone loss from posterior teeth provided that the principles of GTR are applied.

Bone regeneration in extraction sites after immediate placement of an e-PTFE membrane with or without a biomaterial. A report on 12 consecutive cases.

The efficacy in restoring a buccal dehiscence after tooth extraction has been studied in 12 consecutive cases using guided bone regeneration with (6 patients) or without (6 patients) a biomaterial (DFDBA or Bio Oss) beneath an e-PTFE membrane. A correlation between the clinical impression of density at drilling time and the histological signs of bone formation has been evaluated too. The membrane was removed after 6 or 9 months and a biopsy was performed. Clinically, GBR was highly predictable for regeneration of the alveolar bone after tooth extraction with buccal dehiscence. The histology fully confirmed the clinical and radiographical results, showing bone formation in all cases with individual variations in the amount of bone formed. 6-month biopsies from the membrane sites had lamellar bone with large medullary spaces, while a good bone density was observed at 9 months. The membrane/biomaterial sites demonstrated mineralization and large amounts of allograft at 6 months. Thus, bone regeneration seems to take more time when grafting material is used.

Digital image ratio: a new radiographic method for quantifying changes in alveolar bone. Part 1: Theory and methodology.

A new world, digital image ratio (DIR), has been developed for directly measuring changes in alveolar bone. The image on the computer monitor represents the relative mass change between two radiographs. Fourier filtering is used to reduce noise artefacts. This method is validated through an experiment with a step wedge. DIR needs only a preliminary calibration of the experimental conditions of operation and avoids tedious calibrations for each measurement as in the case of digital image substraction. Low-voltage X-ray techniques are suggested for long-term quantitative studies of patients to minimize irradiation doses.

Clinical evaluation of natural coral and porous hydroxyapatite implants in periodontal bone lesions: results of a 1-year follow-up.

This study examines the suitability of 2 bone graft substitutes, natural coral skeleton (NCS) and porous hydroxyapatite (PHA) for treating periodontal bone defects in human subjects, and compares them to debridement alone (DEBR). A total of 30 sites in 10 patients were treated. Measurements were made before treatment and during surgical reexamination 12 months after treatment on lesions filled with NCS (10 sites), PHA (10 sites), or DEBR (10 sites). There was no significant difference in the use of NCS or PHA for 1, 2 wall, or combined defects for the group of parameters measured in this study (clinical probing depth, clinical attachment, gingival recession, bone fill, % bone fill, and crest remodelling). Statistical analysis (Wilcoxon non-parametric test for paired values and ANOVA for repeated measurements) revealed the beneficial effects of using each the biomaterials (57.4% for NCS, 58.1% for PHA, p < 0.86) as opposed to simple debridement (22.2%; p < 0.002; p < 0.004).

Long-term evaluation of endodontic and periodontal treatment.

One hundred and ninety-five teeth in 35 patients with periodontitis who had received both endodontic and periodontal treatment were evaluated 9 years after endodontic treatment and 8 years after periodontal treatment. Some 91.4% of cases were well maintained and 8.6% showed a deterioration in their periodontal condition. Twelve of the 195 teeth with endodontic treatment were lost, eight for periodontal reasons, three as a result of fracture and one because of caries, and the periodontal condition of 10 teeth had worsened. An apical lesion formed on one tooth. The results indicate that the risk of endodontic failure in this group of 195 teeth is very low, and that there is little risk of tooth loss for periodontal reasons, provided that the patients receive supportive periodontal treatment.

Alteration of cytokeratin expression in oral lichen planus.

The purpose of this investigation is to examine the possible biochemical and topographic cytokeratin alterations in lichen planus of oral mucosa. Biopsy samples of clinically normal buccal mucosa (n = 5), normal gingiva (n = 5), lichen planus from buccal mucosa (n = 5), and lichen planus from gingiva (n = 5) were obtained from patients of both sexes. Cytokeratin expression was determined by means of immunohistochemical labeling with use of a battery of monoclonal antibodies against cytokeratins and filaggrin and two-dimensional gel electrophoresis. In buccal mucosa, which is not keratinized cytokeratins 4 and 13 are expressed in the majority. In buccal mucosa lichen planus, the appearance of cytokeratins 1, 2, 10, and 11 coincides with a decrease in cytokeratins 4 and 13 and a moderate increase in cytokeratins 6, 16, 17, and 19. In normal gingiva, which is normally keratinized, the main cytokeratins are 1, 2, 10, and 11. In gingival lichen planus, a slight decrease in these cytokeratins and in cytokeratin 13 expression was noted. Finally, alterations in cytokeratins 5 and 14, explained by marked alterations of basal cells, were observed. The battery of antibodies used in this study, in correlation with two-dimensional gel electrophoresis, could represent useful diagnostic tools that enable the distinction between inflammatory keratosis and so-called quiescent lichen planus. Moreover, this work showed that cytokeratins 1, 2, 10, and 11 and filaggrin are sensitive tools that may help detect early relapse before clinical exacerbation. Finally, these biochemical techniques may be useful to follow the evolution of lichen planus under treatment.

Subepithelial connective tissue grafts in the treatment of gingival recessions. A comparative study of 2 procedures.

Thirty (30) class I and class II recessions in 30 subjects were treated with a subepithelial connective tissue graft procedure. In one group (15 sites), the surgery was carried out in a traditional fashion: the epithelial collar of the graft was preserved and left exposed (CTG group). In the second group (15 sites), the epithelial collar of the graft was removed and the recession areas were conditioned with citric acid. The graft was then sutured and completely immersed under the facial flap which was coronally repositioned (CR group). Clinical assessments included probing depth, probing attachment level, surface area of the recession, and gingival width. These measurements were taken at baseline and at 6 months. In addition, an esthetic evaluation was done. The differences between treatments were not statistically significant except for the augmentation of gingiva (P < or = 0.05). Based on the midfacial measurements taken in the central area of the recession, the mean percentage of root coverage was 69.2%. In the CR group, 3 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 65.5%. In the CTG group, 5 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 94.4%. The mean surface area of root exposure was reduced from 13.82 mm2 and 13.67 mm2 to 2.15 mm2 and 2.34 mm2 for the CR group and the CTG group, respectively. One-hundred percent (100%) of good-to-moderate esthetic results were found by a panel of independent examiners; there was tendency toward better results in the CR group.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokeratin profile of the junctional epithelium in partially erupted teeth.

This study uses cytokeratins (CK) as markers to investigate the phenotype of the junctional epithelium (JE) in partially erupted human teeth. The gingival samples, which were clinically healthy, were carefully dissected from the teeth. Cryostat sections were cut for histological staining, immunofluorescence microscopy and gel electrophoresis. Cytokeratins were extracted after microdissection. The basal and suprabasal epithelial cell markers, cytokeratins 4, 5, 13, 14 and 19 were detected with specific monoclonal antibodies. They showed that the junctional epithelium in erupting teeth has a complex topography. The cytokeratin immunohistochemical profile distinguished between the primary junctional epithelium (CK 5, 14 and 19 in basal and suprabasal cells and CK 13 faintly stained throughout the suprabasal layers) and the adjacent epithelium that had the same cytokeratin profile as the sulcular epithelium (CK 5, 14 and 19 in basal cells and CK 4 and 13 intensively stained in the suprabasal cells). Extraction, two-dimensional electrophoresis and western blotting showed that this transitional JE during eruption also contained CK 6, 16 and perhaps CK 4. Thus, the JE in erupting teeth shows patterns of CK distribution that are very similar to that of developing oral epithelia.

Evaluation of the osteogenic potential of biomaterials implanted in the palatal connective tissue of miniature pigs using undecalcified sections.

Calcium phosphate or calcium carbonate biomaterials are widely used as bone substitutes in periodontal surgery. This study evaluates the osteogenic potential of five different alloplastic biomaterials implanted in the connective tissue of the palatal papilla in miniature pigs. A porous hydroxyapatite (PHA), a dense hydroxyapatite (DHA), a semi-porous hydroxyapatite (SPHA), a tricalcium phosphate (TCP) and a calcium carbonate natural coral (NC) were implanted in a tunnel in the palatal papillae of seven miniature pigs. Undecalcified sections were examined histologically at 1, 2, 3, 4, 8, 12 and 24 wk intervals. Resorbable materials (TCP and NC) were totally resorbed by 24 wk. DHA, PHA and HA showed very limited resorption, although there were multinucleated giant cells in contact with PHA and SPHA. There was no histologically detectable bone formation in contact with or near any of the biomaterials tested. However, several particles of NC, and sometimes of PHA, were surrounded by a dense, mineralized matrix. It is concluded that none of these biomaterials, in their presently available forms, has any bone inducing capacity.

Expanded polytetrafluoroethylene membranes and connective tissue grafts support bone regeneration for closing mandibular Class II furcations.

Twenty-four mandibular buccal Class II furcation lesions in 12 subjects were treated with reconstructive periodontal therapy including citric acid root treatment and replaced flap surgery. Twelve (12) of the lesions received expanded polytetrafluoroethylene (ePTFE) membranes to cover the furcation entrance (ePTFE group) whereas the remaining 12 lesions received a connective tissue graft over the furcation (CTG group). Clinical assessments, including probing depth, probing attachment level, location of gingival margin, direct bone probing, and defect volume, were taken at baseline and at 12 months reentry. In the ePTFE group 30% of the defect volume filled with bone; 36% of the defects exhibited complete bone closure. In the CTG group 19% of the defect volume filled with bone and 18% of these defects exhibited complete bone closure. There were no meaningful clinical differences between treatment groups except in horizontal probing depth change (P < or = 0.05). This study suggests that connective tissue grafts and ePTFE membranes have comparable potential in supporting bone regeneration in mandibular Class II furcation lesions. Further clinical trials with larger numbers of patients and a longer evaluation period are needed to fully compare these procedures.

Chemically separated connective tissue grafts: clinical application and histological evaluation.

Subepithelial palatal connective tissue grafts, separated from the epithelium either chemically (n = 5) or surgically (n = 2) were inserted in patients presenting with gingival recession. Biopsies at the grafted tissue and a portion of non-keratinized mucosa were taken 12 months later. Histology showed keratinization of the newly formed epithelium, and interestingly a deep projection of epithelium into the connective tissue in almost all biopsies, sometimes with an enlargement and a cyst-like space. We conclude that chemical separation of epithelium and connective tissue is clinically feasible for connective tissue grafts and that the subepithelial connective tissue grafting technique should be modified to avoid this projection of epithelium.

[Value of the characterization of cytokeratins in the oropharyngeal epithelium]. / Intérêt de la caractérisation des cytokératines dans les épithéliums oropharyngés.

Cytokeratins are cytoskeletal components and constitute the intermediate filaments of epithelial cells. They are twenty in number and their distribution characterizes a very specific profile in each kind of epithelium. The authors characterized the cytokeratin repartition of the normal oropharyngeal epithelia in order to study their alterations in pathologic tissues, especially in neoplastic and dysplastic epithelia. The normal oropharyngeal epithelium shows cytokeratin pattern of non keratinized stratified epithelia. Three mucosa samples were studied from inflammatory, dysplastic and neoplastic epithelia. According to the alterations of cytokeratin repartition in the two last samples, cytokeratin pattern analysis could allow a characterization or the differentiation stage of neoplastic tissues before the expression of morphogenic criteria.

Changes in cytokeratin expression during the development of the human oral mucosa.

The changes in cytokeratin expression by the developing oral mucosa of 10 to 23-week-old human fetuses were studied by indirect immunofluorescence using a panel of 15 monoclonal antibodies. The lining and masticatory mucosae were incompletely differentiated in 10-wk fetuses, since they expressed identical patterns of cytokeratins (CK 4, 5, 8, 13, 18, 19 and probably CK 14, 16, 17) very similar to that of adult alveolar mucosa. The main difference was the presence of cytokeratins 8, 18 and 19 in embryonic tissues. Cytokeratins 1, 2, 10 and 11 began to appear in gingival and hard palate epithelium from wk 11, predicting the differentiation of the masticatory mucosa by wk 16. The patterns of cytokeratin expression in the 23-wk fetus in the lining and masticatory mucosae appear to be different. In lining mucosa, the only difference from the 10th wk is a decrease in cytokeratins 8, 18 and 19, whereas the pattern of cytokeratin expression in masticatory mucosa (CK 1, 2, 4, 5, 8, 10, 11, 13, 18, 19 and probably CK 14, 16 and 17) is now very near that of adult gingiva. This pattern appears, as in the adult, to be similar to that of the epidermis in the same period.

Suprabasal marker proteins distinguishing keratinizing squamous epithelia: cytokeratin 2 polypeptides of oral masticatory epithelium and epidermis are different.

Terminal differentiation of squamous epithelia is usually characterized by the synthesis of a subset of cytokeratins (CKs) in suprabasal cell layers which become major components of the intermediate filament (IF) bundle cytoskeleton of the maturing cells. We have examined the significance, molecular nature and pattern of synthesis of the elusive human CK 2 by analyzing mRNAs from certain stratified epithelia, using in vitro translation, cDNA cloning. Northern blotting and in situ hybridization. We show that genuine polypeptides with the typical gel electrophoretic mobility of CK 2 exist but that the CK 2 present in the masticatory epithelia of hard palate and gingiva (CK 2p) differs from that found in epidermis (CK 2e) by its amino acid sequence and is encoded by a different gene. The two CKs 2 show only limited sequence homology (71% identical amino acid positions in the rod domain), and the oral CK 2p is more closely related to the corneal CK 3 (86%), as is also indicated by the cross-reaction of monoclonal antibody AE5. By in situ hybridization and immunocytochemistry, we further show that both CK 2e and CK 2p are expressed only in suprabasal cell layers of the specific epithelia where they can accumulate to represent major cytoskeletal proteins. We discuss this tissue-type specificity of CK 2 synthesis in otherwise morphologically and biochemically similar epithelia in relation to differences of IF appearance and packing in upper strata between epidermal and masticatory epithelia as well as to tissue formation and differentiation during development.