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Objective: The influence of radiation backscatter from titanium on DNA damage and migration capacity of human osteoblasts (OBs) and mesenchymal stem cells (MSCs) may be critical for the osseointegration of dental implants placed prior to radiotherapy. In order to evaluate effects of radiation backscatter, the immediate DNA damage and migration capacity of OBs and MSCs cultured on titanium or plastic were compared after exposure to ionizing irradiation. Materials and methods: Human OBs and MSCs were seeded on machined titanium, moderately rough fluoride-modified titanium, or tissue culture polystyrene, and irradiated with nominal doses of 2, 6, 10, or 14 Gy. Comet assay was performed immediately after irradiation, while a scratch wound healing assay was initiated 24 h post-irradiation. Fluorescent live cell imaging documented the migration. Results: DNA damage increased with higher dose and with backscatter from titanium, and MSCs were significantly more affected than OBs. All doses of radiation accelerated the cell migration on plastic, while only the highest dose of 10 Gy inhibited the migration of both cell types on titanium. Conclusions: High doses (10 Gy) of radiation inhibited the migration capacity of both cell types on titanium, whereas lower doses (2 and 6 Gy) did not affect the migration of either OBs or MSCs. Clinical relevance: Fractionated doses of 2 Gy/day, as distributed in conventional radiotherapy, appear not to cause severe DNA damage or disturb the migration of OBs or MSCs during osseointegration of dental implants. [ABSTRACT FROM AUTHOR]

Objectives: Evaluate the modulating effect of ionizing radiation, blood cytokine levels, and bone remodeling of the interface around the implant to understand the radiation mechanisms which can impair the implants receptor site. Material and methods: Sixty rats were submitted to grade V titanium implants in the femurs and were divided into the following groups: no-irradiation (N-Ir): control group with implant only; early-irradiation (E-Ir): implant + irradiation after 24 h; late-irradiation (L-Ir): implant + irradiation after 4 weeks; and previous-irradiation (P-Ir): irradiation + implant after 4 weeks. The animals in the E-Ir, L-Ir, and P-Ir groups were irradiated in two fractional stages of 15 Gy. At 3 days, 2 weeks, and 7 weeks after the final procedure, five animals were randomly euthanized per group. Serum levels of TNF-ɑ, IL-1β, TGF-β, IL-6, M-CSF, and IL-10 were measured from blood collected prior to euthanasia using the ELISA test. The pieces containing the implants were subjected to immunohistochemical labeling using the tartrate acid resistant to phosphatase, osteocalcin, and caspase-3 markers and mCT. The ANOVA test was used for statistical analysis, and the Tukey multiple comparison test (p < 0.05) was applied. Results: The results indicated that ionizing radiation modifies the production of pro- and anti-inflammatory serum cytokines, the expression of proteins involved in bone remodeling and cellular apoptosis, as well as changes in bone formation. Conclusions: The results suggests that a longer period between radiotherapy and implant placement surgery when irradiation occurs prior to implant installation would allow the recovery and renewal of bone cells and avoid future failures in osseointegration. Clinical relevance: The search for modifications caused by ionizing irradiation in bone tissue can indicate the ideal period for implant placement without affecting the osseointegration process. [ABSTRACT FROM AUTHOR]

Objective: Staphylococcus epidermidis, as a primary colonizer, is strongly associated with infections of (dental) implants (i.e., peri-implantitis), but little is known about the surface proteome of this bacterium. For the identification of bacterial adhesins, this study investigated the surface proteome of S. epidermidis adhering directly to titanium implant substrata.Materials and methods: S. epidermidis strain ATTC 35984 was cultured either planktonically or on titanium implant specimens. The surface proteomes were isolated by mutanolysin digestion, and proteins were separated by 2D gel electrophoreses to reveal highly expressed proteins only. Protein spots were visualized by silver staining and proteins were identified by mass spectrometry.Results: Surface proteome analyses of S. epidermidis on titanium identified six expressed proteins. Three proteins were highly expressed on the titanium implants including accumulation-associated protein Q8CQD9. These specific proteins could be potential pathogenicity factors of bacteria in peri-implant biofilms.Conclusion: For the first time, our study identified S. epidermidis surface proteins, which are expressed after adhesion to titanium implant materials.Clinical relevance: Our study reveals possible candidates for a newly protein-based vaccine against peri-implantitis. [ABSTRACT FROM AUTHOR]

Objective: Although an extensive amount of research has demonstrated the positive effects of an enamel matrix derivative (EMD) on soft tissue wound healing around intrabony defects, little information is available describing its effect on peri-implant soft tissues, an area that has recently gained tremendous awareness due to the increasing prevalence of peri-implantitis. The aim of the present study was to assess the role of EMD when gingival fibroblasts were cultured on titanium surface with different surface topographies. Methods: Human primary gingival fibroblasts were cultured on pickled (PT) and sand-blasted with large grit followed by acid etching (SLA) surfaces and assessed for cell adhesion at 2, 4, and 8 h, cell morphology at 2, 4, 8, and 24 h as well as cell proliferation at 1, 3, and 5 days post-seeding. Furthermore, genes encoding collagen 1a1, vascular endothelial growth factor-A (VEGF-A), and fibronectin were assessed by real-time PCR. Human gingival fibroblasts were also quantified for their ability to synthesize a collagen matrix on the various titanium surfaces with and without EMD by immunofluorescence staining. Results: The results from the present study demonstrate that EMD significantly increased cell spreading at 2, 4, 8, and 24 h on PT surfaces and 4, 8, and 24 h on SLA surfaces. Furthermore, proliferation at 5 days on PT surfaces and 3 and 5 days on SLA surfaces was also increased for groups containing EMD. Real-time PCR results demonstrated that the culture of gingival fibroblasts with EMD significantly increased extracellular matrix synthesis of collagen 1 as well as improved mRNA levels of VEGF-A and fibronectin. Collagen1 immuno-fluorescent staining revealed a significantly higher area of staining for cells seeded on PT + EMD at 7 and 14 days and 14 days for SLA + EMD when compared to control samples. Conclusion: The results from the present study favor the use of EMD for colonization of gingival fibroblasts on titanium surfaces by increasing cell growth, spreading, and synthesis of an extracellular matrix. The improvements were primarily irrespective of surface topography. Future animal and human studies are necessary to fully characterize the beneficial effects of incorporating EMD during soft tissue regeneration of implant protocols. Clinical relevance: The use of EMD may speed up the quality of soft tissue integration around dental implants by facilitating gingival cell attachment, proliferation, and matrix synthesis of collagen 1. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to analyze the capacity of a new modified laser surface to stimulate calvarial osteoblasts isolated from neonatal mouse bones to differentiate and form mineralized nodules. Methods: Titanium discs were subjectezd or not to laser irradiation according to specific parameters and characterized. Osteoblasts isolated from neonatal mouse calvaria were cultured over the discs, and the capacity of these cells to proliferate (MTT assay), form mineralized nodules (Alizarin red assay), and enhance alkaline phosphatase activity (ALPase activity) was analyzed. Real-time PCR was used for quantification of gene expression. Results: Laser-irradiated titanium discs (L) presented a rough nano-to-micrometric oxidized surface contrasting with the smooth pattern on polished discs (P). The R on the micrometric level increased from 0.32 ± 0.01 μm on P surfaces to 10.57 ± 0.39 μm on L surfaces. When compared with P, L promoted changes in osteoblast morphology, increased mineralized nodule formation in osteoblasts cultured on the surfaces for 14 days, and enhanced ALPase activity at days 7 and 14. Transcription factors triggering osteoblast differentiation ( Runx2 and Sp7) and genes encoding the bone extracellular matrix proteins collagen type-1 ( Col1a1), osteopontin ( Spp1), and osteocalcin ( Bglap) were upregulated in cells on L surfaces compared with those on P surfaces at days 1-14. Conclusion: Laser treatment of titanium surfaces created a rough surface that stimulated osteoblast differentiation. Clinical relevance: Laser treatment of titanium generates a reproducible and efficient surface triggering osteoblast differentiation that can be of importance for osteointegration. [ABSTRACT FROM AUTHOR]

Objectives: The main purpose of this work was to assess the short-term bone regenerative potential of new osteoconductive implants. The novelty of the study lies in the analysis of the effectiveness of a novel two-step treatment which combines shot-blasting with a thermo-chemical treatment, at very short times after implant placement in a minipig model. Materials and methods: Three hundred twenty implants with four different surface treatments, namely bioactivated surfaces, micro-rough grit-blasted, micro-rough acid-etched and smooth as-machined titanium implants were placed into the bone of 20 minipigs. The percent of bone-to-implant contact was determined 3 days, 1, 2, 3 and 10 weeks after implant placement by histomorphometric analysis. Surface composition, topography and wettability of the implant specimens were analysed. Results: The combination of shot-blasting and thermo-chemical treatment accelerated bone regeneration at early stages in comparison with all other treatments between day 3 and week 3 ( p < 0.05). The value of osseointegration attained at week 2 was maintained until the end of the experiment without any significant changes (percent direct contact ≈ 85 %). This was mostly attributed to the ability of these implants to form in vivo a layer of apatitic mineral that coated the implant and could rapidly stimulate bone nucleation and growth from the implant surface. Conclusions: The surface quality resulting from this treatment on cpTi provided dental implants with a unique ability of rapid bone regeneration and osseointegration. Clinical relevance: This treatment represents a step forward in the direction of reducing the time prior to implant loading. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to investigate the effects of an enamel matrix protein derivative (EMD) on attachment, proliferation, and viability of human SaOs2 osteoblasts on titanium implants. A total of 220 sand-blasted and acid-etched (SLA) titanium discs were placed into 24-well culture plates. Before cell inoculation, McCoy’s 5A medium (MCM) containing EMD at 25 µg/ml, 50 µg/ml, 100 µg/ml, and 200 µg/ml was added, and the culture plates were incubated for 30 min. As control, MCM alone was used. Human osteoblast-like cells (SaOs2) (2×104 cells, fourth passage) were suspended in MCM containing 1% penicillin/streptomycin and 10% fetal bovine serum and then inoculated into the well chambers. The medium was changed after 3 days without the addition of EMD. At days 1, 3, and 6, DNA content of the cells was assessed using the CyQuant cell proliferation assay kit, and mitochondrial activity of the cells was measured using a CellTiter-Glo luminescent cell viability assay. The presence of EMD on the titanium discs at days 1 and 6 was evaluated using immunofluorescence stain (IFS) by means of polyclonal antibodies against amelogenin. Additionally, cell morphology was investigated using scanning electron microscopy. Enamel matrix derivative at 25 µg/ml, 50 µg/ml, 100 µg/ml, and 200 µg/ml demonstrated similar increases in cell proliferation as the control medium at days 3 and 6 (P>0.05 between groups, respectively). Proliferation, however, appeared to be ameliorated with increasing EMD concentrations. At 25 µg/ml and 50 µg/ml, EMD also demonstrated an increase in cell viability similar to the control medium at days 3 and 6 (P>0.05 between groups, respectively), while EMD at 100 µg/ml and 200 µg/ml resulted in statistically significant higher increase in cell viability than in the control medium at day 6 (P<0.001 between groups, respectively). In all test groups, IFS at day 6 was markedly lower than at day 1. Scanning electron microscopy revealed comparable cell morphology in all groups. Within the limits of the present study, it was concluded that EMD enhanced cell proliferation and viability of human SaOs2 osteoblasts on SLA titanium implants in a concentration-dependent manner. [ABSTRACT FROM AUTHOR]