Surface Free Energy and Composition Changes and Ob Cellular Response to CHX-, PVPI-, and ClO2-Treated Titanium Implant Materials.

The study evaluated the interaction of a titanium dental implant surface with three different antibacterial solutions: chlorhexidine, povidone-iodine, and chlorine dioxide. Implant surface decontamination is greatly challenging modern implant dentistry. Alongside mechanical cleaning, different antibacterial agents are widely used, though these could alter implant surface properties. Commercially pure (CP) grade 4 titanium (Ti) discs were treated with three different chemical agents (chlorhexidine 0.2% (CHX), povidone-iodine 10% (PVPI), chlorine dioxide 0.12% (ClO2)) for 5 min. Contact angle measurements, X-ray photoelectron spectroscopy (XPS) analysis, and cell culture studies were performed. Attachment and proliferation of primary human osteoblast cells were investigated via MTT (dimethylthiazol-diphenyl tetrazolium bromide), alamarBlue, LDH (lactate dehydrogenase), and fluorescent assays. Contact angle measurements showed that PVPI-treated samples (Θ = 24.9 ± 4.1) gave no difference compared with controls (Θ = 24.6 ± 5.4), while CHX (Θ = 47.2 ± 4.1) and ClO2 (Θ = 39.2 ± 9.8) treatments presented significantly higher Θ values. All samples remained in the hydrophilic region. XPS analysis revealed typical surface elements of CP grade 4 titanium (Ti, O, and C). Both MTT and alamarBlue cell viability assays showed similarity between treated and untreated control groups. The LDH test revealed no significant difference, and fluorescent staining confirmed these results. Although there was a difference in surface wettability, a high proliferation rate was observed in all treated groups. The in vitro study proved that CHX, PVPI, and ClO2 are proper candidates as dental implant decontamination agents.

In Vitro Biocompatibility Test of Multiwall Carbon Nanotubes with Human Osteoblast Cells: Potential Application for Bone Implant Interface Reinforcement.

Application of multiwall carbon nanotubes (MWCNT) as a filler component in composite materials can lead to remarkable increase in mechanical strength. It is a challenging application to form a living bone tissue biocomposite that is reinforced with MWCNTs at a dental implant-bone interface. The successful biointegration of MWCNT and the implant material depends on the processes of osseointegration, namely surface interactions at the molecular and cellular level. In this work the compatibility of MWCNT with main osseointegration processes has been overviewed with special attention to the toxicity of MWCNT for interacting human cells, and In Vitro experiments were performed with primary human osteoblast cells. The cells were isolated from oral bone fragments and grown in cell culture conditions. Plate wells were covered with MWCNT layers of three different densities. Osteoblast cell suspensions were placed onto the MWCNT layers and into empty plate wells. 24 and 72 hours after seeding the attachment and proliferation of cells was evaluated using Thiazolyl Blue Tetrazolium Bromide (MTT) colorimetric assay. The extent of cell death was characterized by Lactate Dehydrogenase (LDH) assay. The osteoblast cell viability tests show that cells were attached to all investigated surfaces, but with lower rate to higher density MWCNTs. A low level of cell death was observed in each sample type. Phase contrast and fluorescent microscopic observations show that although MWCNTs are not toxic for human primary osteoblast cells, an intense interaction of the cells with MWCNTs reduces their proliferation and markedly affects their morphology.

Photocatalytic enhancement of antibacterial effects of photoreactive nanohybrid films in an in vitro Streptococcus mitis model.

OBJECTIVE: Bacterial adhesion and colonization on implanted devices are major etiological factors of peri-implantitis in dentistry. Enhancing the antibacterial properties of implant surfaces is a promising way to reduce the occurrence of inflammations. In this in vitro study, the antibacterial potential of two nanocomposite surfaces were investigated, as possible new materials for implantology. MATERIAL AND METHODS: The structural and photocatalytic properties of the TiO2 and Ag-TiO2 (with 0.001 wt% plasmonic Ag content) photocatalyst containing polymer based composite layers were also studied and compared to the unmodified standard sandblasted and acid etched Ti discs (control). The presence of visible light induced reactive oxygen species was also verified and quantified by luminol based chemiluminescence (CL) probe method. The discs with adhered Streptococcus mitis were illuminated for 5, 10 and 15 min. The antibacterial effect was determined by the metabolic activities of the adhered and proliferated bacterial cells and protein assay at each time point. RESULTS: The Ag-TiO2 containing surfaces with obvious photocatalytic activity eliminated the highest amount of the metabolically active bacteria, compared to the control discs in the dark, after 15 min illumination. CONCLUSIONS: The plasmonic Ag-enhanced and illuminated surface exhibits significantly better antibacterial activity under harmless visible light irradiation, than the control Ti or TiO2 containing copolymer. The studied surface modifications could be promising for further, more complex investigations associated with dental research on infection prevention in connection with oral implantation.

A simplified in vitro model for investigation of the antimicrobial efficacy of various antiseptic agents to prevent peri-implantitis.

The biofilm formation by oral bacteria on the implant surface is one of the most remarkable factors of peri-implant infections, which may eventually lead to bone resorption and loss of the dental implant. Therefore, the elimination of biofilm is an essential step for the successful therapy of implant-related infections. In this work we created a basic in vitro model to evaluate the antibacterial effect of three widely used antiseptics.Commercially pure (CP4) titanium sample discs with sand blasted, acid etched, and polished surface were used. The discs were incubated with mono-cultures of Streptococcus mitis and Streptococcus salivarius. The adhered bacterial biofilms were treated with different antiseptics: chlorhexidine-digluconate (CHX), povidone-iodine (PI), and chlorine dioxide (CD) for 5 min and the control discs with ultrapure water. The antibacterial effect of the antiseptics was tested by colorimetric assay.According to the results, the PI and the CD were statistically the most effective in the elimination of the two test bacteria on both titanium surfaces after 5 min treatment time. The CD showed significant effect only against S. salivarius.Based on our results we conclude that PI and CD may be promising antibacterial agents to disinfecting the peri-implant site in the dental practice.

TiO2/Ag-TiO2 Nanohybrid Films are Cytocompatible with Primary Epithelial Cells of Human Origin: An In Vitro Study.

Failure of dental implants is caused mainly by peri-implant infections resulting in loss of supporting bone. Since there is no ideal therapy of peri-implantitis, the focus of research has been shifted toward better prevention and the development of antibacterial surfaces. In our study we examined the attachment and proliferation of primary epithelial and MG-63 osteosarcoma cells on Ti dental implants coated with photocatalytic nanohybrid films. Two polyacrylate resin based layers were investigated on commercially pure (CP4) Ti discs: 60 wt% TiO2/40 wt% copolymer and 60 wt% Ag-TiO2/40 wt% copolymer ([Ag] = 0,001 wt%). Surface properties were examined by scanning electron microscopy (SEM) and profilometry. Cell responses were investigated via dimethylthiazol-diphenyl tetrazolium bromide (MTT) and visualized with fluorescence microscopy. Profilometry revealed significant changes in surface roughness of TiO2 (Ra = 1.79 µm) and Ag-TiO2 layers (Ra = 5.76 µm) compared to the polished (Ra(P) = 0.13 µm) and sandblasted, acid-etched control surfaces (Ra(SA) = 1.26 µm). MTT results demonstrated that the attachment (24 h) of epithelial cells was significantly higher on the Ag-TiO2 coated samples (OD540 = 0.079) than on the polished control surfaces (OD540 = 0.046), whereas MG-63 cells did not show any difference in attachment between the groups. After one week, epithelial cells showed slightly increased survival as compared to MG-63 cells. The results suggest that the tested coatings are cytocompatible with epithelial cells, which means that they are not only antibacterial, but they also appear to be promising candidates for implantological use.

Human epithelial tissue culture study on restorative materials.

OBJECTIVES: Health condition of the gingival tissues contacting the surfaces of fixed prostheses is a result of multiple etiologic factors. The aim of the investigation discussed here was to evaluate the attachment and proliferation rate of cultured human epithelial cells on three commonly used restorative materials under in vitro conditions. METHODS: Morphological and chemical structure of polished lithium-disilicate (IPS e.max Press, Ivoclar Vivadent AG, Germany), yttrium modified zirconium dioxide (5-TEC ICE Zirkon Translucent, Zirkonzahn GmbH Srl, Germany) and cobalt chromium alloy (Remanium star, Dentaurum GmbH & Co. KG, Germany) discs were examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM). Human epithelial cells harvested and cultured from one donor, were applied to investigate cell attachment (24h observation) and proliferation (72h observation) via dimethylthiazol-diphenyl tetrazolium bromide (MTT) and AlamarBlue(®) (AB) assays on control surface (cell-culture plate) and on the restorative materials (n=3×20 specimens/material). RESULTS: SEM and AFM revealed typical morphology and roughness features for the materials. Zirconia presented significantly higher Ra value. EDS confirmed typical elements on the investigated restorative materials: lithium-disilicate (Si, O); Zirconia (Zi, Y, O); CoCr (Co, Cr, W). All surfaces except CoCr exhibited significant cell proliferation according to MTT and AB assays after 72h compared to 24h. Among the restorative materials, CoCr samples showed the highest cell attachment as indicated by MTT assay. AB results showed that attachment and proliferation of human epithelial cells is supported more on lithium-disilicate. Both assays indicated the lowest value for zirconia. CONCLUSIONS: The results indicate that the restorative materials examined are equally suitable for subgingival restorations. Lithium-disilicate exhibited the best biocompatibility. CLINICAL SIGNIFICANCE: The examined materials are indicated for use in restorative procedures, directly contacting the sulcular epithelial tissues. Thus it is essential to monitor the biological acceptibility of these materials in order to better understand their clinical properties. The results indicate that Lithium-disilicate is a suitable material for such purposes.

Attachment and proliferation of human osteoblast-like cells (MG-63) on laser-ablated titanium implant material.

Demand is increasing for shortening the long (3-6 months) osseointegration period to rehabilitate patients' damaged chewing apparatus in as short a time as possible. For dental implants, as for biomaterials in general, the bio- and osseointegration processes can be controlled at molecular and cellular levels by modification of the implant surface. One of the most promising of such surface modifications is laser ablation, as demonstrated by our previous results [46]. Commercially pure (CP4) sand-blasted, acid-etched titanium disks (Denti® System Ltd., Hungary) were irradiated with a KrF excimer laser (248 nm, fluence 0.4 J/cm(2), FWHM 18 ns, 2000 pulses), or with a Nd:YAG laser (532 nm, 1.3 J/cm(2), 10 ns, 200 pulses) then examined by SEM, AFM, and XPS. In vitro attachment (24 h) and proliferation (72 h) of MG-63 osteoblast cells were investigated via dimethylthiazol-diphenyl tetrazolium bromide (MTT), alamarBlue (AB) assays alkaline phosphatase quantification (ALP) and SEM. SEM and AFM revealed significant changes in morphology and roughness. XPS confirmed the presence of TiO2 on each sample; after Nd:YAG treatment a reduced state of Ti (Ti(3+)) was also observed. MTT, AB and ALP measurements detected an increase in the number of cells between the 24- and 72 hour observations; however, laser treatment did not affect cell attachment and proliferation significantly.

[Effect of decontaminating solutions on titanium surface: an in vitro study of human epithelial cell culture]. / Dekontamináló anyagok hatása a titánfelszín biointegrációs tulajdonságaira: in vitro humán epithel sejtkultlúra vizsgálatok.

INTRODUCTION: The effects of three different decontaminating solutions in clinical use for peri-implantitis therapy on the chemical structure and surface roughness of commercially pure (CP) Ti were investigated. A further aim was to survey the response of the biological environment to these changes, by examining the attachment and proliferation of human epithelial cells after treatment of the Ti surfaces with these solutions. MATERIALS AND METHODS: CP (grade 4) machined titanium discs (CAMLOG Biotechnologies AG, Switzerland) were treated with 3% H2O2 (5 min), saturated citric acid (pH = 1; 1 min) or chlorhexidine gel (CHX, 5 min). The surface properties were followed through the use of X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The epithelial cell attachment and proliferation was examined by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and bicinchoninic acid (BCA) protein-content assays. RESULTS: XPS showed an intact TiO2 layer on each sample and CHX was adsorbed by the surface, as C-O and/or C=O bond formation was revealed. AFM results gave no significant changes in the roughness after treating the surfaces with the cleaning solutions. While MTT and BCA assays did not show significant differences in epithelial cell attachments, the cell proliferation was significantly increased after H2O2 treatment as compared to CHX (not shown by BCA assays). CONCLUSIONS: The applied decontaminating agents do not damage the Ti surface. H2O2 can be used effectively in decontaminating the implants affected by peri-implantitis, as the human epithelial cell growth was improved, in contrast with CHX.

Effects on titanium implant surfaces of chemical agents used for the treatment of peri-implantitis.

The treatment of peri-implantitis, which causes tissue deterioration surrounding osseointegrated implants, involves surface decontamination and cleaning. However, chemical cleaning agents may alter the structure of implant surfaces. We investigated three such cleaning solutions. Commercially pure (grade 4) machined titanium discs (CAMLOG Biotechnologies AG, Switzerland) were treated with 3% H(2)O(2) (5 min), saturated citric acid (pH = 1) (1 min) or chlorhexidine gel (5 min), and their surface properties were examined by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Human epithelial cell attachment (24-h observation) and proliferation (72-h observation) were investigated via dimethylthiazolyl-diphenyltetrazolium bromide (MTT) and bicinchoninic acid (BCA) protein content assays. AFM revealed no significant difference in roughness of the three treated surfaces. XPS confirmed the constant presence of typical surface elements and an intact TiO(2) layer on each surface. The XPS peaks after chlorhexidine gel treatment demonstrated C-O and/or C=O bond formation, due to chlorhexidine digluconate infiltrating the surface. MTT and BCA assays indicated similar epithelial cell attachments in the three groups; epithelial cell proliferation being significantly higher after H(2)O(2) than after chlorhexidine gel treatment (not shown by BCA assays). These agents do not harm the Ti surface. Cleaning with H(2)O(2) slightly enhances human epithelial cell growth, in contrast to chlorhexidine gel.

Corrosive effects of fluoride on titanium: investigation by X-ray photoelectron spectroscopy, atomic force microscopy, and human epithelial cell culturing.

High fluoride (F(-)) concentrations and acidic pH impair the corrosion resistance of titanium (Ti). Effects of F(-)-containing caries-preventive prophylactic rinses, and gels on Ti were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Human epithelial cell attachment and proliferation were investigated by dimethylthiazol-diphenyl tetrazolium bromide (MTT) and protein content assays. Aqueous 1% NaF solution (3800 ppm F(-), pH 4.5) or high (12,500 ppm) F(-) content gel (pH 4.8) strongly corroded the surface and modified its composition. XPS revealed formation of a strongly bound F(-)-containing complex (Na(2)TiF(6)). AFM indicated an increase in roughness (R(a)) of the surfaces: 10-fold for the NaF solution and smaller for the gel or a mouthwash (250 ppm F(-), pH 4.4). MTT revealed that cell attachment was significantly increased by the gel, but was not disturbed by either the mouthwash or the NaF. Cell proliferation determined by MTT decreased significantly only for the NaF-treated samples; protein content assay experiments showed no such effect. This study indicates that epithelial cell culturing results can depend on the method used, and the adverse effects of a high F(-) concentration and low pH should be considered when prophylactic gels are applied by patients with Ti implants or other dental devices.

[The effect of complete upper denture on phonation]. / A teljes felsô lemezes fogpótlás hangképzésre gyakorolt hatása.

In case of total edentulousness the formation of vowels and consonants is impaired, due to the change of the morphology in the oral cavity. The aim of our study was to estimate the influence of the upper complete denture on the phonation of the patient. Patients wearing total upper denture were asked to utter special words with the prosthesis in the mouth and without it, and the change in the formation of "hissing" sounds were noted. The changes in the pronunciation of vowels and consonants were analyzed with the help of a computer program, which provided objective assessment. The data were analyzed statistically. When wearing the prosthesis the scores of the formant became higher and most examined sounds were pronounced faster (p = 0.006). The articulation of patients accustomed to wearing the full total prosthesis was influenced positively by having the prosthesis in the mouth. As a result of these findings it is recommended that the prosthesis be manufactured keeping these phonetic aspects in mind.