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The aim of this study was to compare the epithelial biological response to machined titanium Ti-6Al-4V grade 5 and titanium Ti-6Al-4V grade 5 coated with zirconia (ZrN) by physical vapor deposition (PVD). Human keratinocytes were cultured in six-well plates. Machined titanium TiAl4V4 grade 5 (T1) and ZrN-coated titanium TiAl4V4 grade 5 (T2) discs were placed in two different wells. The remaining two wells served as control (C). Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were performed to compare the T1 and T2 surfaces. Subsequent analyses were performed to explore the effect of T1 and T2 contact with human keratinocyte HUKE cell lines. Cell viability was evaluated using a trypan blue exclusion test and MTT assay. Cell lysates from C, T1, and T2 were Western blotted to evaluate E-cadherin and Integrin-α6β4 expression. SEM revealed that T2 was smoother and more homogeneous than T1. EDS showed homogeneous and uniform distribution of ZrN coating on T2. Cell viability analyses did not show significant differences between T1 and T2. Furthermore, E-cadherin and Integrin-α6β4 expressions of the epithelial cells cultured in T1 and T2 were similar. Therefore, titanium Ti-6Al-4V grade 5 surfaces coated with ZrN by PVD seem to be similar substrates to the uncoated surfaces for keratinocyte adhesion and proliferation. [ABSTRACT FROM AUTHOR]

Soft tissue sealing around zirconia (ZrO2) abutment is critical for the long-term stability of dental implants. The goal of the study is to develop a strong basal lamina (BL)-mediated epithelial attachment to ZrO2 via a novel physicochemical immobilization method. An electrophoretic fusion (EPF) method was applied to fuse a phosphonic acid (PA) linker to ZrO2 discs. Bindings of the PA linker and the following protease activated receptor 4 (PAR4) were verified by Fourier-transform infrared spectroscopy (FITR). Then, ZrO2 discs were doped in platelet-rich plasma (PRP). Platelet-derived growth factor (PDGF) was measured to assess platelet activation. PRP-doped discs were subsequently co-cultured with human gingival epithelial cells (OBA9) to evaluate establishment of basal lamina-mediated epithelial attachment. The EPF method achieved robust immobilization of the PA linker and PAR4 onto the ZrO2 surface. The resultant PAR4-coupled ZrO2 successfully induced platelet aggregation and activation. Furthermore, a BL-mediated epithelial attachment was established. The results are significant for clinical application to minimize the risk of developing peri-implant diseases. [ABSTRACT FROM AUTHOR]

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The aim of this study was to compare the epithelial biological response to machined titanium Ti-6Al-4V grade 5 and titanium Ti-6Al-4V grade 5 coated with zirconia (ZrN) by physical vapor deposition (PVD). Human keratinocytes were cultured in six-well plates. Machined titanium TiAl4V4 grade 5 (T1) and ZrN-coated titanium TiAl4V4 grade 5 (T2) discs were placed in two different wells. The remaining two wells served as control (C). Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were performed to compare the T1 and T2 surfaces. Subsequent analyses were performed to explore the effect of T1 and T2 contact with human keratinocyte HUKE cell lines. Cell viability was evaluated using a trypan blue exclusion test and MTT assay. Cell lysates from C, T1, and T2 were Western blotted to evaluate E-cadherin and Integrin-α6β4 expression. SEM revealed that T2 was smoother and more homogeneous than T1. EDS showed homogeneous and uniform distribution of ZrN coating on T2. Cell viability analyses did not show significant differences between T1 and T2. Furthermore, E-cadherin and Integrin-α6β4 expressions of the epithelial cells cultured in T1 and T2 were similar. Therefore, titanium Ti-6Al-4V grade 5 surfaces coated with ZrN by PVD seem to be similar substrates to the uncoated surfaces for keratinocyte adhesion and proliferation.

Soft tissue sealing around zirconia (ZrO2) abutment is critical for the long-term stability of dental implants. The goal of the study is to develop a strong basal lamina (BL)-mediated epithelial attachment to ZrO2 via a novel physicochemical immobilization method. An electrophoretic fusion (EPF) method was applied to fuse a phosphonic acid (PA) linker to ZrO2 discs. Bindings of the PA linker and the following protease activated receptor 4 (PAR4) were verified by Fourier-transform infrared spectroscopy (FITR). Then, ZrO2 discs were doped in platelet-rich plasma (PRP). Platelet-derived growth factor (PDGF) was measured to assess platelet activation. PRP-doped discs were subsequently co-cultured with human gingival epithelial cells (OBA9) to evaluate establishment of basal lamina-mediated epithelial attachment. The EPF method achieved robust immobilization of the PA linker and PAR4 onto the ZrO2 surface. The resultant PAR4-coupled ZrO2 successfully induced platelet aggregation and activation. Furthermore, a BL-mediated epithelial attachment was established. The results are significant for clinical application to minimize the risk of developing peri-implant diseases.

Aim: To identify the molecular mechanisms mediating the persistent defensive functions of the self‐renewing junctional epithelium (JE). Materials and methods: Two strains of Wnt reporter mice, Axin2CreErt2/+;R26RmTmG/+ and Axin2LacZ/+, were employed, along with three clinically relevant experimental scenarios where the function of the JE is disrupted: after tooth extraction, after a partial gingivectomy, and after a complete circumferential gingivectomy. Results: Using transgenic Wnt reporter strains of mice, we established the JE is a Wnt‐responsive epithelium beginning at the time of its formation and that it maintains this status into adulthood. After tooth extraction, progeny of the initial Wnt‐responsive JE population directly contributed to healing and ultimately adopted an oral epithelium (OE) phenotype. In the traditional partial gingivectomy model, the JE completely regenerated and did so via progeny of the original Wnt‐responsive population. However, following circumferential gingivectomy, the OE was incapable of re‐establishing a functional JE. Conclusions: A Wnt‐responsive niche at the interface between tooth and oral epithelia is required for a functional JE. [ABSTRACT FROM AUTHOR]

Introduction: Prior to crown lengthening surgery and/or restorative and prosthetic treatment, it is necessary to know the dimensions of the tooth biologic width. In different studies, the biologic width has been measured in different sites and teeth with a healthy periodontium. In this study, the biologic width was measured in different teeth of the mandibular and maxillary arches, and the effect of periodontal/gingival biotype on biologic width was evaluated. Materials & Methods: This cross-sectional study was performed on 163 teeth in 12 subjects, including five males and seven females with an average age of 28 ± 4 years. After injecting the anesthetic agent, the dimensions of the biologic width were measured using a periodontal probe at six sites in all the existing teeth (except the third molars). Periodontal biotype was evaluated and categorized as thin or thick by observing transgingival shade of a probe. The data were analyzed with ANOVA and t-test using SPSS 19 (α = 0.05). Results: The average biologic widths in the molars, premolars, canines, and incisors were 1.90 ± 0.80, 1.72 ± 0.69, 155 ± 0.72, and 1.49±0.64, respectively. There was a significant relationship between the biologic width and the tooth type (p value = 0.000). However, there was no significant relationship between the biologic width and gingival biotype in six points and different sites of the mouth (p value > 0.08). Conclusion: The biologic width dimension varies in different tooth types. The periodontal biotype has no effect on the biologic width dimension. [ABSTRACT FROM AUTHOR]

A review of the peri-implant sulcus, including the histology of the sulcular epithelium, epithelial attachment, and the gingival connective tissue, is presented. The peri-implant junctional epithelial attachment is mediated by hemidesmosomes, as in the periodontal tissue. There is some controversy on the possible attachment of connective tissue fibers to the implant, but current studies indicate a parallel orientation with no insertion of the peri-implant connective tissue fibers. This difference in connective tissue attachment may affect the peri-implant tissue's susceptibility to disease. [ABSTRACT FROM AUTHOR]

Background: Sometimes gingival retractions are associated with high muscular tensional forces and shallow vestibules. Such retractions cause periodontal problems to patients due to the cleaning access limitations. Edlan Mejchar vestibuloplasty technique allows controlling, in one intervention and a single surgical field, etiological factors and a creeping gingival attachment by eliminating tensional forces. Purpose: To describe the effectiveness of Edlan Mejchar technique to solve gum retractions caused by tensional forces in four clinical cases. Description of cases: Four patients with gingival retractions in lower incisors and little adhered gingiva due to lower lip frenulum tension seek dental treatment. Edlan Mejchar vestibuloplasty was the surgical treatment chosen, which consisted of supraperiosteal incisions and internal dissections in connective tissue. Results: The percentage of root coverage achieved was close to 60% and abnormal frenulum insertions were eliminated. Conclusion: Vestibuloplasty through Edlan Mejchar technique showed favorable results in the cases described in which the labial frenum exerted tensional forces on the periodontium of lower anterior teeth. [ABSTRACT FROM AUTHOR]

Osteoporosis (OP) is a global bone disease prevalent in aging in humans, especially in older women. Bisphosphonates (BPs) are commonly used as therapy for OP as it influences hard and soft tissues calcium metabolism. Mucosal and dermal ulceration with exposure of underlying bone arises from incomplete epithelial recovery due to reduced desmosome formation deriving from lack of available calcium. Pathological situations such as bisphosphonate-related osteonecrosis of the jaw have been described. This hypothesis states other situations which demand intact functional desmosomes such as healing skin over chronic pressure points leading to pressure ulcers (as well-known as bedsores, pressure sores, pressure injuries, decubitus ulcers), and hemidesmosomes such as epithelial seals in contact with titanium surfaces will have a higher prevalence of breakdown among patients being treated with BPs. This may be proven through the diminished modulation of calcium ions due to BPs, and its effect on the formation of intercellular gap junctions. [ABSTRACT FROM AUTHOR]

Background Few studies have examined epithelial attachment to zirconia and the proliferative ability of epithelial cells on zirconia surfaces. Purpose To evaluate the adhesion properties of zirconia materials for epithelial cell attachment and compare this with titanium and alumina. Materials and Methods Human oral epithelial cells were cultured on smooth-surfaced specimens of commercially pure titanium ( cpTi), ceria-stabilized zirconia/alumina nano-composite ( P- NANOZR), yttria-stabilized zirconia ( Cercon), and alumina oxide (in Coris AL). The cell morphology, the cell viability and mRNA of integrin β4, laminin γ2, catenin δ2, and E-cadherin were evaluated by SEM, Cell- Counting Kit-8, and real-time PCR, respectively. Results Morphology of cells attached to specimens was similar among all groups. The viable cell numbers on Cercon and in Coris AL after 24 hours culture were significantly higher than for cpTi. Integrin β4, laminin γ2, and catenin δ2 mRNA expression was not different among all groups. However, at 3 and 24 hours after incubation, E-cadherin mRNA expression in the P- NANOZR group was significantly higher than for cpTi. Conclusion Zirconia may support binding of epithelial cells through hemidesmosomes comparable with titanium. Furthermore, P- NANOZR may impart resistance to exogenous stimuli through strong intercellular contacts with peri-implant mucosal cells when used as an abutment and implant superstructure. [ABSTRACT FROM AUTHOR]

Periodontitis is a disease characterized by inflammation of the gingiva that results in the periodontal pocket formation with loss of the supporting periodontal ligament and alveolar bone around teeth. For this reason, traditional non-surgical therapeutic modalities have aimed at eliminating the gingival inflammatory process and preventing the progression of periodontal disease, whereas surgical procedures have been directed towards the elimination and / or regeneration of the defects caused by the disease. During the last two decades, significant research and clinical advances in the area of periodontal therapy have led the therapist closer to achieving the predictable regeneration of the periodontium via the principle of Guided Tissue Regeneration. [ABSTRACT FROM AUTHOR]

Objective: Implant designs that can stimulate and integrate with an epithelial wound-healing process may significantly enhance the efficacy of dental implants. Here, we evaluated the potential of 'step-type' implant systems to improve the sealing between the peri-implant epithelium (PIE) and the implant surface, and investigated the effect of implant structure on PIE down-growth. Materials and methods: Right maxillary first molars were extirpated from rats and implanted with either a straight-type or a step-type implant varying in step height and/or width ( Ns: 0.8 mm height, 0.1 mm width; Ws: 0.8 mm height, 0.2 mm width; Hs: 0.4 mm height, 0.1 mm width). Maxillae were harvested at various time points over 16 weeks to evaluate laminin-5 distribution as an indicator of wound healing and PIE formation, horse-radish peroxidase (HRP) penetration as a measurement of epithelial sealing, and PIE down-growth formation. Results: In all implant models, the PIE formed from the oral sulcular epithelium and spread apically along the implant surface. In the Ws group, HRP penetration was detected only in the coronal region of the PIE at 4 weeks, whereas in the straight-type, it was observed in the apical region and the connective tissue. At 16 weeks, the Ws implants exhibited markedly less PIE down-growth than the Con, Ns or Hs implants, and were equivalent to that observed in natural teeth. Conclusion: The step-type implant system may have the potential for improving epithelial sealing at the tissue-implant interface, as well as reducing apical PIE down-growth, thus enhancing dental implant efficacy. To cite this article: Atsuta I, Ayukawa Y, Ogino Y, Moriyama Y, Jinno Y, Koyano K. Evaluations of epithelial sealing and peri-implant epithelial down-growth around 'step-type' implants. Clin. Oral Impl. Res. 23, 2012 459-466 doi: 10.1111/j.1600-0501.2011.02163.x [ABSTRACT FROM AUTHOR]

Aim: To validate the 'platform switching' concept at oral implants with respect to the preservation of the alveolar crestal bone levels in an animal model. Material & methods: Five minipigs received three implants each with a 0.25 mm implant/abutment mismatch and were placed flush ( T0), 1 mm below ( T1) and 1 mm above ( T+1) the alveolar bony crest, and as a control, one conventionally restored implant placed at the bone level. The implants were randomly inserted flapless into the mandible. Four months after implant insertion, the animals were sacrificed, and undecalcified block sections were obtained and used for histological analyses. Results: The mean values for peri-implant bone resorption were 1.09±0.59 mm (Control), 0.51 (±0.27 mm, T0), 0.50 (±0.46 mm, T+1) and 1.30 (±0.21 mm, T−1), respectively. Statistically significant differences ( P<0.05) were found among the test ( T0, T−1) and the control sites. Control implants presented an average biologic width length of 3.20 mm (±0.33), with a connective tissue adaptation compartment of 1.29 mm (±0.53) and an epithelial attachment of 1.91 mm (±0.71). T0, T+1 and T−1 implants presented with a mean biologic width of 1.97mm (± 1.20), 2.70mm (± 1.36) and 2.84mm (± 0.90), respectively, with a connective tissue adaptation compartment of 1.21mm (± 0.97), 1.21mm (± 0.65) and 1.50mm (± 0.70) and an epithelial attachment of 0.84mm (± 0.93), 1.66mm (±0.88) and 1.35mm (± 0.44), respectively. Differences between the configurations were mainly associated with the length of the epithelial attachment. The epithelial attachment was significantly longer in the C sites than in T0 ( P=0.014). However, no other differences between configurations were detected. Conclusion: If the implants are positioned at the level of the alveolar bony crest, the platform-switching concept may have a minor impact on the length of the epithelial attachment (0.84 vs. 1.91 mm), while the connective tissue adaptation compartment remains relatively unaffected. Moreover, platform switching resulted in less resorption of the alveolar crest (0.58 mm). To cite this article: Farronato D, Santoro G, Canullo L, Botticelli D, Maiorana C, Lang NP. Establishment of the epithelial attachment and connective tissue adaptation to implants installed under the concept of 'platform switching': a histologic study in minipigs Clin. Oral Impl. Res. 23, 2012; 90-94. doi: 10.1111/j.1600-0501.2011.02196.x [ABSTRACT FROM AUTHOR]

Background: In dental implant treatment, the long-term prognosis is dependent on the biologic seal formed by the soft tissue around the implant. The in vitro investigation of the implant-soft tissue interface is usually carried out using a monolayer cell-culture model that lacks a polarized-cell phenotype. This study developed a tissue-engineered three-dimensional oral mucosal model (3D OMM) to investigate the implant-soft tissue interface. Methods: A 3D OMM was constructed using primary human oral keratinocytes and fibroblasts cultured on a skin-derived scaffold at an air-liquid interface. A titanium implant was inserted into the engineered oral mucosa and further cultured to establish epithelial attachment. The 3D OMM was characterized using basic histology and immunostaining for cytokeratin (CK) 10 and CK13. Histomorphometric analyses of the implant-soft tissue interface were carried out using a light-microscopy (LM) examination of ground sections and semi-thin sections as well as scanning electron microscopy (SEM). Results: immunohistochemistry analyses suggests that the engineered oral mucosa closely resembles the normal oral mucosa. The LM and SEM examinations reveal that the 3D OMM forms an epithelial attachment on the titanium surface. Conclusion: The 3D OMM provided mimicking peri-implant features as seen in an in viva model and has the potential to be used as a relevant alternative model to assess implant-soft tissue interactions. J Periodontal 2010;81:1187-1195. [ABSTRACT FROM AUTHOR]

Aim: To assess periodontal health of individuals with a lateral lower lip piercing and describe associated periodontal, dental and mucosal complications. Material and Methods: A split-mouth study was performed in a sample of 50 patients with a lateral lower lip piercing who attended the Periodontal Pathology and Surgery Unit of the Dental School of the University of Barcelona. The patients underwent periodontal, dental and mucosal examination on both the piercing and the control sides. Results: Piercing users were predominantly women (78%), with a mean age of 21.3 years (SD=4.4). The amounts of keratinized and attached gingiva were significantly lower on the piercing side, and the prevalence of gingival recession was higher ( p=0.012). The canine and first bicuspid teeth were the most affected. Tooth fractures and cracks were more frequent on the piercing side (20%) when compared with the control (4%). Mucosal alterations were found in seven patients. Conclusions: The use of lateral lower lip piercings enhances gingival recession and reduces the amounts of keratinized and attached gingiva. These ornaments are also associated with tooth fractures and cracks. [ABSTRACT FROM AUTHOR]

Background: Apical migration of junctional epithelium (JE) occurs in association with periodontal pocket formation. The aim of this study was to investigate the gingival changes occurring during apical migration of the JE following application of factors associated with inflammatory periodontal disease pathogenesis. Methods: Six-week-old male Wistar rats were divided into six groups: three experimental groups to investigate gingival changes following 2, 4, and 8 weeks topical application of lipopolysaccharide (LPS) and proteases and three control groups using pyrogen-free water. After 2, 4 or 8 weeks, nuclear DNA fragmentation was detected in periodontal ligament (PDL) fibroblasts using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method, and proliferative activities of the basal cells and fibroblasts were evaluated through expression of proliferating cell nuclear antigen (PCNA). Collagen destruction was examined histologically. Results: Gingiva treated with LPS and proteases showed an increase in PCNA positive basal cells but not the fibroblasts. Collagen destruction was observed at 2 weeks; apical migration of the JE and TUNEL positive fibroblasts was seen at 4 weeks. Conclusions: Following application of LPS and proteases to rat gingival sulci, the apical migration of the JE appears to occur simultaneously with the apoptosis of PDL fibroblasts, which in turn follows proliferation of the basal cells and collagen destruction. [ABSTRACT FROM AUTHOR]

The article discusses dental work done by Hubert E. Schroeder and Max A. Listgarten in researching the epithelial attachment apparatus. The two men began their research in the late 1960s when the attachment mechanisms of the junctional epithelium were relatively unknown. In 1970 they worked together for eight weeks in writing a paper which described a lamina which mediates the attachment of the epithelium with the gingival sulcus bottom. This partnership continued for 40 more years, resulting in various other dental discoveries.

Background: The junctional epithelium (JE) is a unique structure that makes contact with both a non-renewable hard tooth surface and with a basement membrane (BM) facing the connective tissue. Ultrastructurally, this attachment occurs through hemidesmosomes (HD) and a basal lamina-like extracellular matrix which, on the tooth side, is termed the internal basal lamina. In this study we investigated the expression of basal cell markers in the tooth-facing (TF) cells of JE. Methods: Samples of healthy marginal gingiva were removed by careful dissection. The expression of laminin-5 was used to indicate TF cell preservation in double immunofluorescence labeling and confocal laser scanning microscopy. Results: The results show that integrin alpha6beta4 and laminin-5 colocalize unequivocally in the TF cells. The results also show the specific expression of the basal cytokeratin 14 and the alpha(v) integrin subunit in the TF cells. All 3 major hemidesmosomal components BP180, BP230, and HD1 antigen are likewise present. On the other hand, type IV collagen, laminin-1/10, type VII collagen, and the BM proteoglycan perlecan are all absent from the dento-epithelial junction. Conclusions: The results indicate that the epithelium-tooth interface is a unique structure wherein epithelial cells adhere by means of bona fide hemidesmosomes to an epithelium-derived extracellular matrix lacking most of the common BM components. Moreover, TF cells differ from connective tissue facing (CTF) cells, not only by their cell surface molecules and their production of extracellular matrix, but also by their cytoskeletal architecture. [ABSTRACT FROM AUTHOR]

Background: The epithelial cell adhesion molecule CEACAM1 exhibits an interesting dynamic expression during tooth development. It is first expressed in the reduced enamel epithelium, its expression then increases in the orally faced reduced epithelium and the overlying oral epithelium that then fuse to give rise to the junctional epithelium. The expression of CEACAM1 remains at high levels in the junctional epithelium, in contrast to the surrounding oral sulcular epithelium which shows much lower expression levels. We investigated if the high expression levels of CEACAM1 and the loosely organized cells characteristic of the junctional epithelium are genetically programmed or result from bacterial infiltration. Methods: Oral tissues from germ-free rats and mice and animals with conventional bacterial flora were analyzed by transmission electron microscopy and immunohistochemical staining for CEACAM1. Results: The junctional epithelium of both germ-free and conventional animals was identical with respect to both CEACAM1 expression and morphology. Also the presence of leukocytes was the same in both types of animals. Conclusions: The results indicate that the characteristic morphology and the high expression levels of CEACAM1 in the junctional epithelium are genetically programmed and not a result of bacterial infiltration. This suggests that CEACAM1 has an important role for the structural integrity of the junctional epithelium. This conclusion was supported by the observation that the junctional epithelium does not express any E-cadherin, which is another abundant epithelial cell adhesion molecule. [ABSTRACT FROM AUTHOR]

Background: Keratinocyte growth factor (KGF) is a stromally derived growth factor of the fibroblast growth factor (FGF) family with paracrine effects targeted to influence the growth arid differentiation of epithelia. Regional and temporal changes in KGF expression play important roles in the development and maintenance of epithelial structures and in epithelial wound healing. Differing patterns of expression of KGF by fibroblasts in the gingival region could therefore be related to the observed regional variation in the differentiation and behavior of gingival epithelia. Methods: The in vitro and in vivo patterns of expression of KGF mRNA in human gingival and periodontal fibroblasts were examined using reverse transcription polymerase chain reactions (RT-PCR) and in situ hybridization with digoxigenin-labeled riboprobes. The patterns observed for human gingiva were compared with those for human skin and for murine tissues. Results: Gingival and periodontal fibroblasts showed expression of KGF transcripts in vitro, and the degree of expression was markedly influenced by the presence of retinoic acid, an agent known to influence patterns of epithelial differentia lion. Sections of human and murine gingiva and skin showed regionally variable expression of transcripts with the cells expressing KGF in the subepithelial, rather than the deeper, connective tissues and periodontium. Conclusions: The results point to a role of KGF in the maintenance of normal growth and differentiation of gingival epithelia. A lack of KGF expression by periodontal fibroblasts in vivo is expected to hinder apical epithelial migration and thus stabilize the epithelial attachment. The effects of retinoic acid (RA) on KGF expression in vitro provide an indirect mechanism by which RA may regulate the growth and differentiation of gingival epithelia. [ABSTRACT FROM AUTHOR]

Background: The role played by the internal basal lamina (IBL} and hemidesmosomes between an implant and the peri-implant epithelium (PIE) in the adherence of the epithelium to the implant is controversial. This study used rat maxilla implantation models to clarify the ultrastructure of the PIE-implant interface. Methods: Ti-6AI-4V implants were inserted either immediately or 2 weeks after the extraction of the upper left first molar of 6- or 4-week-old rats, respectively. The junctional epithelium (JE) of the upper right molars in the same animals was used as a control. Four weeks after implantation, the animals are sacrificed to prepare specimens for light and immunoelectron microscopy. Results: Under light microscopy, the PIE appeared to attach to the implant surface. Ultrastructurally, IBL, consisting of the lamina densa and lamina lucida, and hemidesmosomes were formed only in the lower region, and rarely in the middle region, of the PIE-implant interface. In control teeth, the IBL and hemidesmosomes formed throughout the dento-JE interface. Laminin-1 was found in the IBL and also in the vesicles and vacuoles of the PIE and JE cells. Statistical analysis showed that there was also a significant difference in the amount of IBL between the PIE-implant and dento-JE interfaces. Conclusions: PIE attached to the implant via hemidesmosomes and IBL in the lower region of the PIE-implant interface. Although PIE cells may secrete laminin-1, which contributes to epidermal cell adhesion, the PIE which attaches to implants only in the lower region of the interface is considered to be the poorly adhered epithelium. [ABSTRACT FROM AUTHOR]

Features of natural masticatory function, of physiological attrition, both occlusal and approximal, and of continuing tooth eruption in adult life need to be borne in mind in considering how the chronic inflammatory periodontal diseases and dental caries have become so widespread. Evidence is reviewed showing that teeth continue to erupt in adulthood, that natural masticatory function prevented plaque accumulation at the approximal risk site of onset of both CIPDs and caries, that epithelial attachment to cementum may be physiological, and that periodontal attachment studies must be age-related. [ABSTRACT FROM AUTHOR]

THE EXPRESSION OF ADHESION MOLECULES and the local production of chemotactic cytokines within the epithelium are considered to be key events in neutrophil (PMN) migration at sites of mucosal infections. In their journey toward the gingival sulcus, PMNs have been shown to selectively migrate through the junctional epithelium. Little, however, is known about the molecular mechanisms involved in this key process aimed at the control of subgingival bacterial plaque. This investigation describes the expression of IL-8 mRNA-positive cells and the establishment of a gradient of intercellular adhesion molecule-1 (ICAM-1) receptors within the junctional epithelium of clinically healthy gingival. Expression of ICAM-1 and IL-8 was topographically associated with the area of PMN migration; i.e., the junctional epithelium. Levels of ICAM-1 expression increased from the basal cells toward the surface of the junctional epithelium and thus toward areas exposed to bacterial challenges. IL-8 mRNA-positive cells were also present at highest density in the most superficial junctional epithelial layers. The combination of the haptotactic stimuli, resulting from the interaction of the PMN's β2 integrin receptors with the gradient of ICAM-1 expression, and the location of IL-8 mRNA-positive cells, consistent with the establishment of a discrete PMN chemotactic source, may play an important physiologic role in efficiently routing PMNs to the gingival sulcus. This process contributes to the maintenance of a local host-parasite equilibrium and to the limitation of PMN-associated tissue damage. [ABSTRACT FROM AUTHOR]

This study examined the directly attached cells (DAT cells) of the human junctional epithelium from teeth extracted for advanced periodontal disease. The monolayer nature of the DAT cells remaining on the tooth surface after extraction offers a unique opportunity to study their morphology and activity in situ. We collected DAT cells and examined them by transmission electron microscopy and by autoradiography of cells labeled with ³H-thymidine. Our morphological results suggest that degenerative changes associated with pocket formation affect individual cells rather than regions of the DAT cell population at one time. The epithelial attachment apparatus (EAA) appeared to be the most resistant structure persisting on the tooth surface during the degeneration of the individual DAT cells. The new technique developed for two-dimensional observation of the sheet of DAT cells labeled in situ on the tooth surface in culture showed that the attached cells, even in periodontal disease, exhibit proliferative ability, suggesting a regenerative role for the DAT cells. [ABSTRACT FROM AUTHOR]

The structural and functional barrier preventing the free advancement of microbial plaque subgingivally along the tooth surface is formed by the junctional epithelial (JE) cells directly attached to the tooth (DAT cells). The mechanism leading to degeneration of the DAT cells is not known. In the present study we examined the possible role of short chain fatty acids (SCFAs) on epithelial cells by making use of 2 epithelial cell cultures (HaCaT and ERM) and an explant culture model of human JE. The SCFAs butyrate and propionate were used in concentrations found in human plaque and gingival crevicular fluid (0.25-16.0 mM). The SCFAs had no effect on primary cell adhesion nor on the epithelial attachment apparatus (EAA). By contrast, even 0.25 mM of butyrate significantly retarded epithelial cell growth. Similar effects with propionate were first observed at concentrations higher than 1.0 mM. The retardation of epithelial cell growth was found to be due to inhibition of cell division. Furthermore, after butyrate treatment dense accumulations of intermediate filaments and cytoplasmic vacuolization were characteristically seen in cells adjacent to cells of normal appearance. This suggests that some cells of the growing epithelial cell population are more sensitive to the SCFAs than others, and agrees with previous reports on the DAT cells of periodontally-involved teeth in vivo. The results suggest that SCFAs are microbial factors that play a role in the initiation and progression of periodontal pocket formation by impairing epithelial cell function rather than having a direct effect on the EAA. [ABSTRACT FROM AUTHOR]

The basal lamina anionic sites of the epithelial attachment apparatus (EAA) were investigated at the electron microscopic level in adult rat periodontium. After 1 M NaCl junctional epithelium detachment, an irregular and fluffy basal lamina-like structure appeared to cover the cementum surface. This structure reacted positively with polyethyleneimine (PEI), a strongly cationized ultrastructural tracer, appearing to be composed of highly electron-dense microaggregates. Depending on section plane, double-tracked structures of undefined length were found within PEI precipitates and closely related to cementum collagen fibrils. After nitrous acid de-N-sulphation, 8 nm wide sets of two parallel lines were clearly identified. "Double tracks", i.e., sets of paired lines with peripherical PEI electron-dense material, were found to self-assemble to form dimers, clusters or more complex organizational patterns. From sensitivity towards nitrous acid oxidation and positive control observations, it was concluded that basal lamina anionic sites in the EAA. represented by PEI microaggregates, contain heparan sulfate proteoglycans (HSPGs). Furthermore, high resolution ultrastructural images demonstrated that HSPGs adopt a morphological appearance of "double tracks" in the tissue. On the other hand, the present findings suggest that HSPGs clusters, never found in the mucosal basement membrane used as positive control, may be related to a functional specificity of the tissue at the dento-gingival junction. [ABSTRACT FROM AUTHOR]