Identification of Sjögren's syndrome oral fluid biomarker candidates following high-abundance protein depletion.

OBJECTIVE: SS is an autoimmune exocrinopathy affecting ∼1 million patients in the USA that is diagnosed mostly in middle-aged women. Oral fluids (OFs) serving as the mirror of the body were suggested as an ideal non-invasive diagnostic tool. Previously we developed depletion techniques for OF high-abundance proteins to increase visualization of low-abundance proteins. Therefore the aim of this study was to examine the effect of depletion pretreatments on the identification potential of SS OF biomarker candidates. METHODS: Unstimulated OFs were collected from 18 female SS patients and 18 healthy age- and gender-matched controls. High-abundance proteins were depleted using affinity and immunodepletion methodologies followed by semi-quantitative two-dimensional gel electrophoresis and quantitative dimethylation liquid chromatography tandem mass spectrometry (LC-MS/MS). To initially validate the MS results, western blotting was performed. RESULTS: The use of depletion strategy before proteomics analysis increased identification ability by 3-fold. Overall, 79 biomarker candidates were identified. Proteins with the most pronounced fold changes were related to SS serum or tissue factors. In addition, bioinformatics analysis of proteins with a >3-fold increase in SS patients showed calcium-binding proteins, defence-response proteins, proteins involved in apoptotic regulation, stress-response proteins and cell motion-related proteins. Preliminary validation by western blotting of profilin and CA-I indicated similar expression profile trends to those identified by quantitative MS. CONCLUSION: The significance of OF novel depletion methodologies is clearly demonstrated for increased visibility of biomarker candidates as well as for unveiling possible mechanisms involved in this syndrome. This represents a major contribution to our ability to use OF as a future diagnostic fluid.

In vitro adhesion of staphylococci to diamond-like carbon polymer hybrids under dynamic flow conditions.

This study compares the ability of selected materials to inhibit adhesion of two bacterial strains commonly implicated in implant-related infections. These two strains are Staphylococcus aureus (S-15981) and Staphylococcus epidermidis (ATCC 35984). In experiments we tested six different materials, three conventional implant metals: titanium, tantalum and chromium, and three diamond-like carbon (DLC) coatings: DLC, DLC-polydimethylsiloxane hybrid (DLC-PDMS-h) and DLC-polytetrafluoroethylene hybrid (DLC-PTFE-h) coatings. DLC coating represents extremely hard material whereas DLC hybrids represent novel nanocomposite coatings. The two DLC polymer hybrid films were chosen for testing due to their hardness, corrosion resistance and extremely good non-stick (hydrophobic and oleophobic) properties. Bacterial adhesion assay tests were performed under dynamic flow conditions by using parallel plate flow chambers (PPFC). The results show that adhesion of S. aureus to DLC-PTFE-h and to tantalum was significantly (P < 0.05) lower than to DLC-PDMS-h (0.671 ± 0.001 × 10(7)/cm(2) and 0.751 ± 0.002 × 10(7)/cm(2) vs. 1.055 ± 0.002 × 10(7)/cm(2), respectively). No significant differences were detected between other tested materials. Hence DLC-PTFE-h coating showed as low susceptibility to S. aureus adhesion as all the tested conventional implant metals. The adherence of S. epidermidis to biomaterials was not significantly (P < 0.05) different between the materials tested. This suggests that DLC-PTFE-h films could be used as a biomaterial coating without increasing the risk of implant-related infections.

Enhancement of silicon using micro-patterned surfaces of thin films.

Micro-textured biomaterials might enhance cytocompatibility of silicon-based micro-electro-mechanical system (bio-MEMS) dummies. Photolithography-physical vapour deposition was used to produce diamond-like carbon (DLC) or Ti squares and circles on silicon, and also their inverse replicas; then DLC and Ti were compared for their guiding potential, using a SaOS-2 cell model. Scanning electron microscopy at 48 hours indicated cells were well-spread on large-sized patterns (several cells on one pattern) and assumed the geometrical architecture of underlying features. Medium-sized patterns (slightly smaller than solitary indicator cells) were inhabited by singular cells, which stretched from one island to another, assuming longitudinal or branching morphologies. On small-sized patterns (much smaller than individual cells;rpar; cells covered large micro-textured areas, but cellular filopodia bypassed the bare silicon. Immunofluorescence and confocal laser scanning microscopy indicated that the actin cytoskeleton and vinculin-containing adhesion junctions were present on the patterned areas, but not on the bare silicon. Cell density/coverage disclosed a 3.4-3.7-fold preference for the biomaterial patterns over silicon substrate (p 0.001). Differences in the cellular response between materials were lost at 120 hours when cells were confluent. The working hypothesis was proven; enhancement by micro-patterning depends on the pattern size, shape and material and can be used to improve biocompatibility during the initial integration phase of the device.

Adhesion, spreading and osteogenic differentiation of mesenchymal stem cells cultured on micropatterned amorphous diamond, titanium, tantalum and chromium coatings on silicon.

It was hypothesized that human mesenchymal stromal cell (hMSC) can be guided by patterned and plain amorphous diamond (AD), titanium (Ti), tantalum (Ta) and chromium (Cr) coatings, produced on silicon wafer using physical vapour deposition and photolithography. At 7.5 h hMSCs density was 3.0-3.5 x higher (P < 0.0003, except Ti) and cells were smaller (68 vs. 102 microm, P 0.000006-0.02) on patterns than on silicon background. HMSC-covered surface of the background silicon was lower on Ti than AD patterns (P = 0.015), but at 5 days this had reversed (P = 0.006). At 7.5 h focal vinculin adhesions and actin cytoskeleton were outgoing from pattern edges so cells assumed geometric square shapes. Patterns allowed induced osteogenesis, but less effectively than plain surfaces, except for AD, which could be used to avoid osseointegration. All these biomaterial patterns exert direct early, intermediate and late guidance on hMSCs and osteogenic differentiation, but indirect interactions exist with cells on silicon background.

[Electrostimulation for the treatment of dry mouth].

Xerostomia is a very common condition, which not only involves dry mouth feeling, but can also lead to psychosocial distress, impaired quality of life, and complications, such as dental caries and oral candidiasis. It is generally induced by hypofunction of salivary glands, which has a wide variety of etiologies, such as Sjögren's syndrome, radiotherapy to the head and neck and side effects of medications. Current therapies rely on saliva substitutes and pharmacological stimulation of the parasympathetic system. These treatment modalities are somewhat limited by their short-term efficacy, high cost and drug interactions or other adverse effects. Local transcutaneous or permucosal electrostimulation in areas close to the nerves participating in the salivary autonomic reflex has been found to increase salivary secretion in animal and clinical experiments and to relieve symptoms of dry mouth in patients with salivary gland hypofunction. This concept is reviewed to update the readers on the current status and potential of intraoral miniature electrostimulating devices. They offer promise as an optional safe and non-chemical treatment of xerostomia.

Long-term bone tissue reaction to polyethylene oxide/polybutylene terephthalate copolymer (Polyactive) in metacarpophalangeal joint reconstruction.

The poly-L/D-lactide 96/4 joint scaffolds are used to engineer fibrous tissue joints in situ for the reconstruction of metacarpophalangeal joints. In this experimental study, a supplementary elastomeric stem made of Polyactive 1000PEO70PBT30 (a segmented block copolymer of polyethylene oxide and polybutylene terephtalate with 70/30 PEO/PBT ratio) was used to anchor the joint scaffold in the arthroplasty space. Eleven resected fifth metacarpophalangeal joints of minipig were reconstructed and evaluated radiologically and histologically for 3 years. Plain joint scaffold and Swanson silicone implant arthroplasties (11 of each) in metacarpophalangeal joints of minipig served as controls. Altogether fore limbs of eighteen minipigs were operated for the study. Deleterious tissue reaction with dramatic signs of osteolysis and inflammatory foreign-body reaction was observed around the Polyactive stems. The mean maximum diameter of the osteolytic stem cavity was statistically wider when compared to the mean maximum diameter of Swanson implant group during the first postoperative year. Numerous osteoclasts were found at the margins of the osteolytic areas. No direct bone contact could be seen. At 1 year osteoblastic regeneration and formation of new trabecular bone followed. Finally the foreign-body reaction settled, but the adjoining bones were at this stage highly sclerotic and composed of coarse trabeculae. In contrary to previous in vivo studies suggesting biocompatibility, osteoconductivity and capability to bond to bone, Polyactive 1000PEO70PBT30 stem in this setting caused massive osteolytic lesions and foreign-body reactions.

The use of biodegradable scaffold as an alternative to silicone implant arthroplasty for small joint reconstruction: an experimental study in minipigs.

Biodegradable poly-L/D-lactide (P(L/D)LA) 96/4 joint scaffold arthroplasty is a recently clinically introduced concept in the reconstruction of small joints, however its histology and function in vivo is unknown. In this experimental study on 11 minipigs the fifth metacarpophalangeal joints were reconstructed using a P(L/D)LA 96/4 joint scaffold or Swanson silicone implant. They were evaluated until 3 years. The P(L/D)LA 96/4 joint scaffold formed a porous interposition spacer, which maintained the arthroplasty space and induced fibrous tissue in-growth in situ. No differences were found in the range of motion or arthroplasty space width between the study groups. The P(L/D)LA 96/4 joint scaffold was initially filled with vascular, loose connective tissue. Along with degradation of the scaffold, the in-grown connective tissue matured and condensed turning into dense fibrous connective tissue. After 3 years, the P(L/D)LA 96/4 joint scaffold had almost completely degraded and been replaced by dense fibrous connective tissue. These findings indicate that P(L/D)LA 96/4 joint scaffold arthroplasty leads to the formation of a functional fibrous joint. The avoidance of permanent foreign material makes the biodegradable joint scaffold an attractive alternative for small joint arthroplasty.

Enhanced osteolytic potential of monocytes/macrophages derived from bone marrow after particle stimulation.

BACKGROUND: Total hip replacement can be complicated by periprosthetic osteolysis. Monocytes/macrophages play a major role in the formation of the foreign body granulomas induced by wear debris. We hypothesized that periprosthetic monocytes/macrophages do not only accelerate inflammatory and osteoclast-mediated osteolytic processes, but also resorb periprosthetic bone directly by themselves. This study was designed to evaluate the osteolytic potential in vitro of monocytes/macrophages derived from bone marrow. METHODS: Monocytes/macrophages were produced by filtration of rat bone marrow cells, followed by culture in the presence of macrophage-colony stimulating factor (M-CSF). Monocyte/macrophage properties were ascertained using immunocytochemistry and phagocytic activity. Osteolytic cytokines and extracellular matrix degrading proteinases were quantified at the mRNA level. RESULTS: Adherent cell fraction was immunoreactive for the monocyte/macrophage specific marker CD68 and active in the phagocytosis of carbon particles up to 72 h. They also showed immunoreactivity to cathepsin K, IL-1beta, IL-6, and M-CSF, but mostly did not react to TRAP. mRNA levels of osteolytic cytokines and extracellular matrix degrading proteinases were enhanced, but that of RANKL were not. Monocytes/macrophages resorbed dentine discs and carbonated calcium phosphate was very actively resorbed after stimulation with titanium particles. DISCUSSION: Harvested bone marrow cells expressed monocyte/macrophage phenotype, but not osteoclastic markers. The capacity of these cathepsin-K-positive phagocytic cells to resorb dentine discs and carbonated calcium phosphate in vitro suggests a direct role of monocytes/macrophages in bone resorption and periprosthetic osteolysis. The finding supports our hypothesis and previous histomorphometric observations on the presence of such osteolytic macrophages in vivo around loosening prosthesis.

Update on UHMWPE research: from the bench to the bedside.

Ultra-high molecular weight polyethylene (UHMWPE) is the key material for achieving excellent long-term results in total joint arthroplasties. Despite the fact that there has been a substantial amount of research and development over the years, new aspects of this material are still controversial and the most recent innovations have had a variable reception regarding clinical use. Advancements in conventional UHMWPE in the 1990s (nitrogen atmosphere irradiation, barrier package) were further improved by introduction of first-generation crosslinked polyethylene, as seen both from laboratory findings and clinical results. However, while clinical data on first-generation highly crosslinked polyethylene (HXLPE) showed reduced wear in the medium-term, academic and industrial research have helped to refine the material further, to overcome criticisms regarding residual oxidation and potential material fracture. Present concerns, although less nowadays, relate to the post-irradiation techniques used to stabilize the crosslinked polyethylene, namely annealing and remelting. Current topics of research interest include in vivo oxidation, second-generation highly crosslinked polyethylene, vitamin E doped or blended polyethylene, fracture mechanics, and consequences of wear. Some of these improvements derived from recent research are already available to the orthopedic community, and others will appear in the next few years. This review gives an overview of these topics, and the latest advancements are described in detail with a view to help the orthopedic surgeon make scientifically sound decisions when selecting material for total-joint implants. We conclude the review by affirming that today's state-of-the-art material is no longer conventional UHMWPE, but HXLPE.1.

The influence of sex steroids on Sjögren's syndrome.

Sjögren's syndrome is an autoimmune disease affecting the exocrine glands, most typically salivary and lacrimal glands. In Sjögren's syndrome, the acinar cells of these glands are damaged and destroyed, leading to diminished secretion of saliva and tear fluid. Accordingly, the current American-European criteria of Sjögren's syndrome include xerostomia (dry mouth) and keratoconjunctivitis sicca (dry eyes). In addition to these sicca symptoms and signs, the diagnostic criteria require autoimmune features in the form of Sjögren's syndrome SS-A and/or SS-B autoantibodies and lymphocyte infiltrates in labial salivary glands. Majority of patients with Sjögren's syndrome are women and the diagnosis is usually done when they are 40-50 years old. The cause of Sjögren's syndrome is unknown, but taking into account the female dominance and the late onset, our hypothesis is that sex steroids play a key role in the etiology of Sjögren's syndrome. More specifically, we believe that the driving factor behind Sjögren's syndrome could be lack of androgens. It has been shown that patients with Sjögren's syndrome have low concentrations of circulating dehydroepiandrosterone sulfate (DHEA-S) compared to age-matched healthy controls. Our hypothesis is that patients with Sjögren's syndrome suffer from an insufficient local androgen effect in the exocrine target tissues of the disease because of low systemic levels and/or ineffective local intracrine handling of DHEA-S prohormone. To further clarify the role of sex steroids and the eventual deficiency of androgens, salivary glands are studied using protein markers regulated by androgens or estrogens.

Biocompatibility of polylactides in the middle ear: an experimental animal study.

OBJECTIVE: To study the suitability of resorbable polylactides for reconstruction in middle ear surgery. EXPERIMENTAL ANIMALS: Twenty-four chinchillas. INTERVENTIONS: Twenty chinchillas were operated on using 2 types of polylactides inserted into the middle ear and outer ear canal, 10 animals in each group. At 6 months, the animals were killed, and their temporal bones were removed for sectioning. Degree of inflammation, fibrosis, degradation of polylactide material, and new bone formation were assessed histologically. MAIN OUTCOME MEASURES: Polylactide implants caused only a mild local inflammation, with no difference between the 2 materials tested. CONCLUSION: Polylactide acid-based middle ear implants were successfully used in the reconstructive middle ear surgery. Resorption occurred without complications.

Collagenases in gingival crevicular fluid in type 1 diabetes mellitus.

BACKGROUND: Studies have demonstrated that high levels of collagenase activity in gingival crevicular fluid (GCF) are associated with degradation of periodontal tissues in progressive periodontitis compared to periodontally healthy tissues. Because the activation of collagenases is an important issue in periodontitis, we have studied the activation of collagenase in gingival crevicular fluid samples of diabetic patients. METHODS: Collagenase activity was studied in human gingival crevicular fluids. Twenty-two poorly controlled diabetic patients (e.g., blood glucose: 11.0+/-0.7 mmol/l; hemoglobin A1c [HbA1c]: 9.6%+/-0.3%) and five well-controlled diabetic patients were compared to six chronic periodontitis subjects and five healthy controls. Collagenase activity against type I collagen was measured using sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis quantitated by laser densitometry. RESULTS: The poorly controlled diabetic patients had more alveolar bone loss than the well-controlled diabetic subjects and controls (P<0.001; t test). The activity of collagenases in GCF in poorly controlled diabetic patients was similar to that seen in chronic periodontitis subjects (P>0.05) but higher than in healthy controls (P<0.01; t test), whereas there was no difference between the well-controlled diabetic subjects and systemically healthy controls (P>0.05; t test). CONCLUSION: Poorly controlled diabetes is strongly related to periodontal tissue destruction, and collagenases in GCF may mediate and reflect this effect.

Effects of two multi-step self-etch primer/adhesives on apoptosis in human gingival fibroblasts in vitro.

Various in vitro studies have shown induction of apoptosis by monomers incorporated to dental restorative materials and adhesive resins, while information regarding the effect of monomer combinations as commercially available products on apoptosis is limited. The aim of this study was to investigate the effects of two multi-step self-etch primer/adhesive systems on apoptosis of cultured primary human gingival fibroblasts. Cells were treated up to 48 h with Clearfil SE Bond (Kuraray, Japan) and FL Bond (Shofu, Japan) at 1:1000 v:v ratio to determine cell proliferation, using 0.02 mM staurosporine as positive control. Apoptosis was assessed using propidium iodide/acridine orange (PI/AO) staining, compared to nontreated controls. When compared to FL Bond, exposure of gingival fibroblasts to Clearfil SE Primer and Clearfil SE Bond resulted in a higher degree of cell proliferation. PI/AO staining revealed typical morphological features of apoptosis in FL Bond and Staurosporine groups, while some cells cultured in the presence of primer and adhesive components of Clearfil SE Bond showed nuclear fragmentation, indicative of early apoptosis. Our results indicate that apoptotic potential of the multi-step self-etch adhesives were material-dependent within the 48 h test period.

Immunohistochemical evaluation of inflammatory mediators in failing implants.

It was hypothesized that peri-implant tissue around loosening dental implants may contain cytokines with a potential to regulate osteoclasts. Peri-implant and/or gingival samples from loosened implants, chronic periodontitis (CP), and normal controls (n = 10 samples in each group) were analyzed using immunohistochemical staining to observe tumor necrosis factor alpha (TNF-alpha), interleukin 1-alpha (IL-1alpha), IL-6, platelet-derived growth factor A (PDGF-A), and transforming growth factor alpha (TGF-alpha). These cytokines were found in foreign-body giant cells, macrophages, fibroblasts, and epithelial cells. TNF-alpha, IL-1alpha, and IL-6 were increased (P < .05; unpaired t test) in peri-implantitis and CP, whereas PDGF-A and TGF-alpha were not. In conclusion, cytokines with a potential to activate osteoclasts were found in both peri-implantitis and CP, but the cytokine profiles differed in that IL-1alpha was the most prevalent cytokine in the former and TNF-alpha was the most common in the latter. These cytokines may contribute to peri-implant bone loss/loosening by stimulating formation and activity of osteoclasts and might be an amenable target for local therapies with cytokine modulators.

A bioactive hybrid three-dimensional tissue-engineering construct for cartilage repair.

The aim was to develop a hybrid three-dimensional-tissue engineering construct for chondrogenesis. The hypothesis was that they support chondrogenesis. A biodegradable, highly porous polycaprolactone-grate was produced by solid freeform fabrication. The polycaprolactone support was coated with a chitosan/polyethylene oxide nanofibre sheet produced by electrospinning. Transforming growth factor-ß3-induced chondrogenesis was followed using the following markers: sex determining region Y/-box 9, runt-related transcription factor 2 and collagen II and X in quantitative real-time polymerase chain reaction, histology and immunostaining. A polycaprolactone-grate and an optimized chitosan/polyethylene oxide nanofibre sheet supported cellular aggregation, chondrogenesis and matrix formation. In tissue engineering constructs, the sheets were seeded first with mesenchymal stem cells and then piled up according to the lasagne principle. The advantages of such a construct are (1) the cells do not need to migrate to the tissue engineering construct and therefore pore size and interconnectivity problems are omitted and (2) the cell-tight nanofibre sheet and collagen-fibre network mimic a cell culture platform for mesenchymal stem cells/chondrocytes (preventing escape) and hinders in-growth of fibroblasts and fibrous scarring (preventing capture). This allows time for the slowly progressing, multiphase true cartilage regeneration.

The effect of geometry and abduction angle on the stresses in cemented UHMWPE acetabular cups--finite element simulations and experimental tests.

BACKGROUND: Contact pressure of UHMWPE acetabular cup has been shown to correlate with wear in total hip replacement (THR). The aim of the present study was to test the hypotheses that the cup geometry, abduction angle, thickness and clearance can modify the stresses in cemented polyethylene cups. METHODS: Acetabular cups with different geometries (Link: IP and Lubinus eccentric) were tested cyclically in a simulator at 45 degrees and 60 degrees abduction angles. Finite element (FE) meshes were generated and two additional designs were reconstructed to test the effects of the cup clearance and thickness. Contact pressures at cup-head and cup-cement interfaces were calculated as a function of loading force at 45 degrees, 60 degrees and 80 degrees abduction angles. RESULTS: At the cup-head interface, IP experienced lower contact pressures than the Lubinus eccentric at low loading forces. However, at higher loading forces, much higher contact pressures were produced on the surface of IP cup. An increase in the abduction angle increased contact pressure in the IP model, but this did not occur to any major extent with the Lubinus eccentric model. At the cup-cement interface, IP experienced lower contact pressures. Increased clearance between cup and head increased contact pressure both at cup-head and cup-cement interfaces, whereas a decreased thickness of polyethylene layer increased contact pressure only at the cup-cement interface. FE results were consistent with experimental tests and acetabular cup deformations. CONCLUSION: FE analyses showed that geometrical design, thickness and abduction angle of the acetabular cup, as well as the clearance between the cup and head do change significantly the mechanical stresses experienced by a cemented UHMWPE acetabular cup. These factors should be taken into account in future development of THR prostheses. FE technique is a useful tool with which to address these issues.

Establishment of Green Fluorescent Protein and Firefly Luciferase Expressing Mouse Primary Macrophages for In Vivo Bioluminescence Imaging.

Macrophages play a key role in tissue homeostasis as well as in a range of pathological conditions including atherosclerosis, cancer, and autoimmunity. Many aspects of their in vivo behavior are, however, poorly understood. Bioluminescence imaging (BLI) with green fluorescent protein (GFP) and firefly luciferase (FLUC) labelled autologous reporter macrophages could potentially offer a powerful tool to study macrophage biology, but this approach has been hindered by the relative difficulty of efficient gene transfer into primary macrophages. Here we describe a straightforward method for producing large numbers of GFP/FLUC expressing mouse primary macrophages utilizing lentivirus vector, cyclosporine, and a double infection strategy. Using this method we achieved up to 60% of macrophages to express GFP with correspondingly high FLUC signal. When injected into the circulation using a mouse model of local biomaterial induced inflammation and osteolysis, macrophages were initially detectable within the lungs, followed by systemic homing to the local area of chronic inflammation in the distal femur. In addition, transduced macrophages maintained their ability to assume M1 and M2 phenotypes although the GFP/FLUC expression was altered by the polarizing signals. These reporter macrophages could prove to be valuable tools to study the role of macrophages in health and disease.

Radiographic signs in the temporomandibular joint in Reiter's disease.

AIMS: To investigate whether involvement of the temporomandibular joint (TMJ) can occur in men with Reiter's disease (RD). METHODS: Forty-nine men with RD and 49 individually matched (gender, age and dentition type) controls with no known general joint disease were screened for findings in the TMJ by panoramic tomography. RESULTS: Duration of subjective symptoms (e.g., pain) in the masticatory system correlated with duration of RD (P = .05). In the RD group, severity of clinical signs of symptoms correlated with the progressive form of RD (P = .01), number of affected joints (P = .0001), and involvement of the cervical (P = .0001) and lumbar spine (P = .05). Patients with RD more frequently had radiographic findings (33%) in the condyle of the TMJ than did controls (10%) (P = .002). The most characteristic radiographic sign in the condyle in the RD group was unilateral erosion (12%). CONCLUSION: Patients with RD often have erosion causing pain and dysfunction in the TMJ. Potential masticatory system problems for such patients should be brought to the attention of dentists and physicians.

Reduction of wear in total hip replacement prostheses by amorphous diamond coatings.

Wear-debris-induced periprosthetic bone loss and aseptic loosening is regarded as the main long-term problem of total hip replacements (THRs). In this study the amount of wear debris from articulating surfaces of THRs was reduced so as to be close to negligible by the use of high-quality amorphous diamond (AD) coatings deposited by pulsed plasma arc techniques. The wear rates determined in a commercial hip simulator for 15 million walking cycles (corresponding to about 15 years of clinical use) in serum lubrication were even 1,000,000 times lower than the clinical values for conventional THRs (polyethylene-metal or metal-metal pairs). Elimination of wear debris and good biomechanical performance should provide a substantial improvement of the clinical longevity of the THRs.

Attachment of oral gram-negative anaerobic rods to a smooth titanium surface: an electron microscopy study.

PURPOSE: Attachment of bacteria to titanium may differ not only between bacterial species but also between strains within a species. The aim of the present in vitro study was to examine differences in bacterial attachment using 4 gram-negative anaerobic species of bacteria that are considered potential periodontal pathogens. MATERIALS AND METHODS: The attachment of clinical and laboratory strains (n = 23) representing 2 Fusobacterium nucleatum subspecies, Porphyromonas gingivalis, and Prevotella intermedia to smooth, commercially pure titanium was examined using scanning electron microscopy. RESULTS: All bacterial strains were attached to the smooth titanium surface by their outer membrane. F nucleatum cells were poorly attached to the titanium, unlike P gingivalis or P intermedia cells, but only slight differences were observed in the quantity of attached cells between the strains within each bacterial group. DISCUSSION: In favorable conditions, some anaerobes can attach directly to an inert titanium surface. Microbial adhesion and subsequent colonization on the dental implant surface can lead to infection of the peri-implant tissue. CONCLUSION: The results indicated that the avidity of bacterial attachment to a smooth titanium surface varies between species of oral gram-negative anaerobes but not between strains.