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.

Characterization of cytokeratin patterns in the developing human tongue.

The characterization of cytokeratin (CK) in adult oral mucosa and developing teeth have been well documented in human. Cytokeratin distribution in developing oral mucosa has not yet been described. The aim of this study was to identify the expression of CK in human fetal tongue (week 10 to week 23) and to correlate the results with morphological maturation. Simple epithelial CK are expressed in all cell layers during the early stages, essentially in peridermal cells. From the 14th week, CK 18 is present only in the taste buds, making this polypeptide a reliable marker for this sensory organ. CK 4 and 13 are expressed from the 10th to the 23rd week by both ventral and dorsal lingual epithelia. Terminal differentiation keratins (CK 1, 2 and 10-11) can only be detected immunohistochemically at the 14th week in some cells on the external surface of some papillae. The number of these papillae and positive cells increase at the 19th and 23rd weeks. The terminal differentiation markers are expressed several weeks earlier than the formation of a well-distinguished keratinized layer.

Identification of late differentiation antigens of human cornified epithelia, expressed in re-organized desmosomes and bound to cross-linked envelope.

Little is known about the process leading to desquamation in cornified epithelia. We describe late differentiation antigens (Ag) specific for human cornified squamous epithelia, defined by two murine monoclonal antibodies (MoAb), G36-19 and B17-21, produced after immunization with plantar stratum corneum (SC). Histologically, in epidermis both Ag are cytoplasmic in the lower stratum granulosum (SG), become pericellular in the upper SG, and progressively disappear in the lower SC. In contrast, they persist up to the desquamating corneocytes in the palmoplantar epidermis and hard palate epithelium, as well as in the three cornified epithelial components of the inner root sheath (IRS) of the hair follicle (HF). Cytologically, both Ag are expressed as surface spots only on rough corneocytes. They are largely preserved on cross-linked envelopes (CLE) of the fragile type. Ultrastructurally, both Ag appear in keratinosome-like cytoplasmic vesicles in the upper stratum spinosum (SS) and the SG keratinocytes, then are found in both the regular and reorganizing desmosomes of the SG keratinocytes, and lastly in the corneocyte-specific reorganized desmosomes we propose to name corneodesmosomes. On CLE, the Ag are located on fibrils gathered over the external side of the envelope. Immunochemically, the G36-19--defined epitope is sequential and shared by five non-cytokeratin protein antigens of molecular weight 33.5, 36.5, 40, 49, and 52 kD, the higher molecular weight polypeptides being possibly precursors of the 33.5-kD protein. In contrast, the B17-21 epitope, unaccessible by immunoblotting, is probably conformational. In long-term cultured keratinocytes, the Ag are only expressed when epidermal sheets are morphologically differentiated. The expression is enhanced in the absence of fetal calf serum (FCS) and of epidermal growth factor (EGF). G36-19 and B17-21 Ag participate in a corneodesmosome-CLE superstructure that is probably involved in corneocyte cohesiveness and partly responsible for the mechanical resistance of the SC. These Ag are relevant markers for studying desmosomal maturation during epidermal differentiation and desquamation.

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.

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.

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)

Freeze-dried skin allografts. A human clinical and histological study.

Free gingival autografts still remain the most predictable method for creating attached gingiva. However, a need exists for sources of connective tissue other than the patient's own connective tissue. Yukna et al. have proposed freeze-dried skin (FDS) allografts as a substitute for gingival autografts. The purpose of the present study was to evaluate FDS allografts on humans, clinically and histologically. Ten FDS allografts and two free gingival (FG) autografts were performed on ten patients, two of them receiving both FDS and FG grafts. Clinical measurements were made before surgery, immediately after surgery and then 2 and 6 months after surgery. After 4 and 24 months, biopsies were performed on both FG and FDS grafts. Routine histologic staining was done. The results show a mean gain of attached gingiva of 0.32 mm with a range from 0 to 0.8 mm. Compared biopsies sections of FDS allografts and FG autografts show that the tissue obtained with the FDS allografts do not display the histomorphologic pattern of attached gingiva. The FDS allografts do not seem to represent a good substitute to free gingival autografts. However, they might be used successfully as a biological bandage.

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.

Cytokeratin patterns of human oral mucosae in histiotypic culture.

In a three-dimensional culture model, oral epithelial differentiation was investigated ultrastructurally and biochemically for cytokeratin expression. Epithelia from the hard palate, gingiva and alveolar mucosa grown on freely floating collagen lattices populated with fibroblasts from homotypic origins, and fed with medium containing 10% delipidized fetal calf serum for 21 days before analysis, stratified and differentiated to basal cuboidal cells, polyhydral spinous cells and elongated superficial cells. The epithelium of palatal origin had non-nucleated superficial cells resembling orthokeratinized cells. The upper spinous cells had keratohyalin-like granules. The corresponding cells of gingival and alveolar mucosal origins retained their nuclei and had smaller numbers of keratohyalin-like granules. Basal cell keratins (CK 5 and 14) and those of hyperproliferation (CK 6 and 16) were consistently found in all epithelia. Furthermore, simple epithelial keratins (CK 18 and 19) were variably expressed by cells from different oral origins. In epithelial cells from the alveolar mucosa, CK 13 and 19 formed major bands, which correlates with their expression in vivo. In contrast, these polypeptides were either absent or formed minor bands in extracts of gingival and hard palatal cells. Although in small quantities, keratins of terminal differentiation (CK 1, 2, 10 and 11) were detected in gels prepared from palatal epithelia. This expression correlates with the higher morphological differentiation of these cells in this model. The model is of interest for studies of epithelial differentiation, as the differentiation markers of keratinized epithelia (CK 1 and 10) were expressed by cells from palatal origin, and those of non-keratinized epithelia (CK 4, 13 and 19) were prominent in cells from alveolar mucosal origin.

A comparative biochemical and immunological analysis of cytokeratin patterns in the oral epithelium of the miniature pig and man.

In man, cytokeratin constitutes a family of 19 polypeptides that show different but distinct distribution patterns in the various epithelia. Changes in these patterns may occur during epithelial development and differentiation. The cytokeratin patterns in the oral mucosa of the miniature pig, an animal used in studies of wound healing, were investigated. Surgical biopsies were obtained from the gingiva, hard palate and alveolar mucosa of both man and pig. The cytokeratins were analysed by immunofluorescence, two-dimensional gel electrophoresis and by immunoblotting. Nine monoclonal antibodies were used to identify the different cytokeratin polypeptides in cryostat sections. Two-dimensional gel electrophoresis showed that pig oral mucosa contains at least 10 different polypeptides, five of the acidic type I and five of the basic type II cytokeratins. These were different from the human cytokeratin polypeptides and accordingly were designated P1-P10, according to their molecular weight and isoelectric mobility. Their molecular weight varied between 48 and 69 kdalton and the pHi varied between 5 and 7.3. Immunoblotting showed the monoclonal antibody Ks 13.1 (anticytokeratins Nos 13 and 14) to cross-react with the pig polypeptides P10 and P8. Immunolocalization showed that all the antibodies cross-reacted with the pig tissue except Ks 19.1 (anticytokeratin No. 19). It was possible to differentiate between pig alveolar mucosa, which expressed only P3, P4, P5, P8 and P10, and the gingival and hard palatal mucosae, which expressed all 10 polypeptides except P5. This distinction was made by antibody 6B10 (anticytokeratin No. 4), which reacted only with alveolar mucosa; antibody Ks 13.1, which strongly reacted with uncornified mucosa but weakly with cornified mucosa (gingiva and palate); and any of RKSE60, Kk 8.60 or EE21.6 (anticytokeratin No. 10, anticytokeratins Nos 10 and 11 and anticytokeratins Nos 1, 2, 10 and 11, respectively), which reacted strongly with cornified mucosa but weakly, if at all, with uncornified mucosa. These findings provide a baseline for studies on epithelial differentiation in the miniature pig such as in wound healing.

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.

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.

[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.

[Gingival grafts and implant surgery]. / Greffes gingivales et chirurgie implantaire.

Although there is no scientific data to support the concept, it is proposed that a band of attached gingiva around implants is clinically desirable. This can be accomplished by the use of gingival grafts either at the time of the second operation or at a later date. This seems preferable to mucogingival surgery performed before implants insertion.

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.

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).

[Clinical and histological evaluation of a new filling material: natural coral]. / Evaluation clinique et histologique d'un nouveau matériau de comblement: le corail naturel.

A clinical and histological study was performed to evaluate the effects of natural coral micro-granules in the treatment of infrabony defects. 12 defects in 11 patients were selected for treatment. The therapy was assessed using standardized radiographs, pocket probings and gingival margin levels 12 months after treatment. The mean initial pocket depth was 9.6 +/- 1.5 mm and at the bony defect 6.08 +/- 2.53 mm. Results showed a gain in attachment of 3 +/- 1.5 mm and a mean reduction in pocket depth of 3.9 +/- 2 mm. Two biopsies taken at 8 and 18 months post-operatively show different stages of bone formation around the coral particles.

Cytokeratin profiles in oral epithelial: a review and a new classification.

This article proposes a classification of oral epithelial and summarizes recent literature of cytokeratin expression in the oral cavity. The oral epithelial are subdivided into two major groups: superficial and deep epithelia. Epithelial lining the oral cavity, i.e., superficial, are essentially stratified squamous epithelia, with the exception of taste buds. The epithelium covering the dorsal tongue is a combination of keratinized and non-keratinized epithelia. Deep epithelia are of two kinds, odontogenic and glandular epithelia. This study provides a classification of the cytokeratins expressed in the oral cavity in healthy and pathological situations based on published data and our own studies. The profiles of these polypeptides in different oral epithelia should provide information that may be used in various disciplines of oral medicine.