Effect of direct current on surface structure and cytocompatibility of titanium dental implants

The biofilm removal effect and osteogenic potential on the titanium surface by electrolytic cleaning: An in vitro comparison of electrolytic parameters and five techniques

OBJECTIVES

To determine the optimal current and time of electrolytic cleaning (EC), compare its biofilm removal effect with generic treatments and evaluate the influence of EC to surface characteristics and osteogenic potential of SLA titanium (Ti) discs.

MATERIALS AND METHODS

The six-species biofilm-covered Ti discs were placed as cathodes in physiologic saline and subjected to various current and time treatments. The residual biofilms were evaluated to determine the optimal parameters. The contaminated Ti discs were randomized and treated by rotating Ti brush; ultrasonic-scaling with metal tips; ultrasonic-scaling with PEEK tips; air-polishing and EC. The residual biofilms were compared using a lipopolysaccharide kit (LPS), scanning electron microscope (SEM), confocal laser scanning microscopy and colony-forming unit counting. Non-contaminated Ti discs were treated and characterized. The bone marrow mesenchymal stem cells (BMSCs) were cultured on treated non-contaminated Ti discs. The adhesion, proliferation, alkaline phosphatase (ALP) activity and osteocalcin level of BMSCs were assessed.

RESULTS

The parameters at 0.6A5min were considered optimal. For LPS and SEM, EC promoted a significantly greater biofilm removal than the other groups. There were no changes in the Ti discs' colour, topography, roughness and chemical elements after EC, and the electrolysis-treated Ti discs obtained a super-hydrophilic surface. EC positively impacted the proliferation and ALP activity of BMSCs, surpassing the efficacy of alternative treatments.

CONCLUSIONS

EC achieves a near-complete eradication of contaminants on the SLA surface, causes no surface damage with improved hydrophilicity, and promotes the early osteogenic response of BMSCs, which makes it a promising treatment for peri-implantitis.

Investigation of different electrochemical cleaning methods on contaminated healing abutments in vitro: an approach for metal surface decontamination

BACKGROUND

To evaluate the effects of electrolysis on cleaning the contaminated healing abutment surface and to detect the optimal condition for cleaning the contaminated healing abutment.

METHODS

Ninety healing abutments removed from patients were placed in 1% sodium dodecyl sulfate solution and randomly divided for electrolysis with 7.5% sodium bicarbonate in the following three different apparatuses (N = 30): two stainless steel electrodes (group I), a copper electrode and a carbon electrode (group II), and two carbon electrodes (group III). The samples were placed on cathode or anode with different electric current (0.5, 1, and 1.5 A) under constant 10 V for 5 min. Electrolyte pH before and after electrolysis were measured. Then, the samples were stained with phloxine B and photographed. The proportion of stained areas was calculated. The surface was examined with a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS).

RESULTS

Electrolyte pH decreased after electrolysis at 1 A and 1.5 A in group I and II. Applying cathode at 1 A in group III, the amount of residual contamination was the lowest in all the conditions examined in the present study. SEM images revealed that applying cathode at 1.5 A in group I induced a rough surface from the smooth surface before the treatment. EDS analysis confirmed that the surfaces treated on cathode at 1 A in group III revealed no signs of organic contamination.

CONCLUSION

Electrolysis of using carbon as electrodes, placing the contaminated healing abutments on cathode, and applying the electric current of 1 A at constant 10 V in 7.5% sodium bicarbonate could completely remove organic contaminants from the surfaces. This optimized electrochemical cleaning method seems to be well worth investigation for the clinical management of peri-implant infections.

Enhancing osseointegration of titanium implants through large-grit sandblasting combined with micro-arc oxidation surface modification

PURPOSE

The demand for titanium dental implants has risen sharply. However, the clinical success rate of implant surgery needs to be improved. In this paper, we report a novel surface modification strategy, large-grit sandblasting combined with micro-arc oxidation (SL-MAO), aiming to promote peri-implant bone formation and osseointegration of titanium implants.

MATERIALS AND METHODS

Modified titanium samples were prepared by large-grit sandblasting and acid etching (SLA), micro-arc oxidation (MAO), and SL-MAO. The resulting topographical changes and chemical composition of the samples were examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively, and the biocompatibility and bioactivity were analyzed by bone-marrow mesenchymal stem cells (BMMSC) adhesion tests. Modified titanium implants were also inserted into the femurs of beagle dogs, and their competence of osseointegration was appraised by quantitative histomorphometry and micro-computed-tomography (micro-CT) analyses.

RESULTS

Compared to SLA and MAO techniques, SL-MAO surface modification further enhanced titanium surfaces by creating a topographic morphology characterized by both micron-sized craters and sub-micron-scale pits, and resulted in superior chemical composition, which promoted cell adhesion, proliferation, and osteogenic differentiation. SL-MAO-modified titanium implants osseointegrated more efficiently than SLA or MAO controls, with significantly higher bone-area (BA) ratio and bone-implant contact (BIC) in the peri-implant region.

CONCLUSIONS

The SL-MAO surface modification technique optimized the surface properties of titanium implants and enhanced peri-implant bone formation and osseointegration.

Advanced inorganic nanocomposite for decontaminating titanium dental implants

Oral hygiene and regular maintenance are crucial for preserving good peri-implant health. However, available prophylaxis products and toothpastes, which are optimized for cleaning teeth, tend to contaminate and abrade implant surfaces due to their organic components and silica microparticles, respectively. This study aims to develop an organic-free implant-paste based on two-dimensional nanocrystalline magnesium phosphate gel and hydrated silica nanoparticles (20-30% w/w) for cleaning oral biofilm on titanium dental implants. The surface chemistry, morphology, and bacterial load of contaminated Ti disks before and after decontamination using prophylaxis brushing with toothpaste and implant-paste were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and fluorescence spectroscopy. Both commercial toothpastes and implant-paste remove bacteria, however, only implant-paste protects Ti metal from abrasion and removes organic contaminants. XPS showed a significant decrease of carbon contamination from 73% ± 2 to 20% ± 2 after mechanical brushing with implant-paste compared to 41% ± 11 when brushing with commercial toothpastes (p < 0.05). Fluorescence microscopy revealed that bacteria load on biofilm contaminated Ti (44 × 10³  ± 27 × 10³ /µm² ) was significantly reduced with the implant-paste to 2 × 10³  ± 1 × 10² /µm² and with a commercial toothpaste to 2.9 × 10³  ± 7·10² /µm² . This decay is relatively higher than the removal achieved using rotary prophylaxis brush alone (5 × 10³  ± 1 × 10³ /µm² , p < 0.05). Accordingly, this novel implant-paste shows a great promise as an efficient decontamination approach. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 761-772, 2019.

Electrochemical removal of biofilms from titanium dental implant surfaces

The infection of dental implants may cause severe inflammation of tissue and even bone degradation if not treated. For titanium implants, a new, minimally invasive approach is the electrochemical removal of the biofilms including the disinfection of the metal surface. In this project, several parameters, such as electrode potentials and electrolyte compositions, were varied to understand the underlying mechanisms. Optimal electrolytes contained iodide as well as lactic acid. Electrochemical experiments, such as cyclic voltammetry or measurements of open circuit potentials, were performed in different cell set-ups to distinguish between different possible reactions. At the applied potentials of E < -1.4 V, the hydrogen evolution reaction dominated at the implant surface, effectively lifting off the bacterial films. In addition, several disinfecting species are formed at the anode, such as triiodide and hydrogen peroxide. Ex situ tests with model biofilms of E. coli clearly demonstrated the effectiveness of the respective anolytes in killing the bacteria, as determined by the LIVE/DEAD™ assay. Using optimized electrolysis parameters of 30 s at 7.0 V and 300 mA, a 14-day old wildtype biofilm could be completely removed from dental implants in vitro.

Production of bone mineral material and BMP-2 in osteoblasts cultured on double acid-etched titanium

Background

The study of osteoblasts and their osteogenic functions is essential in order to understand them and their applications in implantology. In this sense, this study try to study BMP-2 production and bone matrix deposition, in addition to other biological variables, in osteoblasts cultured on a rough double acid-etched titanium surface (Osseotite®, Biomet 3i, Palm Beach Garden, Florida, USA) in comparison to a smooth titanium surface (machined) and a control Petri dish.

Material and Methods

An in vitro prospective study. NHOst human osteoblasts from the femur were cultured on three different surfaces: Control group: 25-mm methacrylate dish (n = 6); Machined group: titanium discs with machined surface (n = 6) and Experimental group: titanium discs with a double acid-etched nitric and hydrofluoric Osseotite® acid surface (n = 6). A quantification of the mitochondrial membrane potential, and studies of apoptosis, mobility and adhesion, bone productivity (BMP-2) and cellular bone synthesis were carried out after culturing the three groups for forty-eight hours.

Results

A statistically significant difference was observed in the production of BMP-2 between the experimental group and the other two groups (22.33% ± 11.06 vs. 13.10% ± 5.51 in the machined group and 3.88% ± 3.43 in the control group). Differences in cellular bone synthesis were also observed between the groups (28.34% ± 14.4% in the experimental group vs. 20.03% ± 6.79 in the machined group and 19.34% ± 15.93% in the control group).

Conclusions

In comparison with machined surfaces, Osseotite® surfaces favor BMP-2 production and bone synthesis as a result of the osteoblasts in contact with it.

Key words:BMP-2, Cytoskeleton, cell culture, bone matrix, apoptosis, cell viability.

Can Direct Current Electrotherapy Be Used for Patients With Orthopedic Implants?

Introduction:

Although electrotherapy appears to have particularly interesting applications in the field of postoperative orthopedic rehabilitation, relatively little scientifically based research has been conducted in the area of electrotherapy with regard to safety involving patients with orthopedic implants.

Method:

Three electrotherapy forms were tested, such as high-volt stimulation (HVS), transcutaneous electric nerve stimulation (TENS), and galvanic current (GAL), using a model system containing a metal implant plate to evaluate whether heating in excess of 3°C would occur.

Results:

All changes in temperature for HVS, GAL, and TENS therapeutic electrical currents observed in our model system fall below the predefined 3°C.

Conclusion:

To the best of our knowledge, this is the first experimental based observation that prolonged exposure to a direct electrical current at therapeutic strength does not result in heating of metal titanium plates.

Decontamination of titanium implants using physical methods

OBJECTIVES

Current decontamination methods of titanium (Ti) implant present limited success in achieving predictable re-osseointegration. We hypothesized that even though these techniques could be useful in elimination of bacteria, they might be unsuccessful in removing organic contaminants and restoring the original surface composition. The aim of this study was to assess the effect of four decontamination methods on the surface chemistry and bacterial load of biofilm-contaminated implant surfaces in order to improve implant surface decontamination.

MATERIAL AND METHODS

The ability of clinically available methods such as metal and plastic curettes, Ti brushes and Er: YAG laser to decontaminate Ti implant surfaces was assessed. Surface morphology, chemical composition and properties of machined Ti discs (Ø 5.0 and 1.0 mm thick) were analysed before and after oral biofilm contamination using scanning electron microscope and X-ray photoelectron spectroscopy. The presence and viability of bacteria were evaluated with live-dead assays.

RESULTS

Biofilm contamination created an organic layer rich in hydrocarbons and bacteria that covered entirely the Ti surfaces. This organic layer has tightly adhered to Ti surfaces and could not be completely removed with any of the methods assessed. Ti brushes achieved greater elimination of organic contaminants and bacteria than curettes and Er: YAG laser; however, none of them was able to restore the original surface chemistry. Alternatively, Er: YAG laser-treated surfaces showed the lowest live-to-dead bacterial ratio.

CONCLUSIONS

Ti brushes were more effective than curettes (metal or plastic) and Er: YAG laser in decontaminating Ti implant surfaces, although none of these techniques was able to completely eliminate surface contamination. Er: YAG laser was more effective than curettes and Ti brushes in killing the biofilm bacteria.