Application of oxygen ion implantation to titanium surfaces: effects on surface characteristics, corrosion resistance, and bone response

Development of a Novel Nanotextured Titanium Implant. An Experimental Study in Rats

This animal study evaluated the osseointegration level of a new nanotextured titanium surface produced by anodization. Ti-cp micro-implants (1.5 mm diameter by 2.5 mm in length) divided into two groups: titanium nanotextured surface treatment (Test Group) and acid etched surface treatment (Control Group). Surface characterization included morphology analysis using scanning electron microscopy and wettability by measuring contact angle. Sixteen Wistar rats were submitted to two micro implants surgical placement procedures. In each rat, one type of micro implant placed in each tibia. The animals sacrificed after two (T1) and six weeks (T2) post-implantation. After the euthanasia, tibias processed for histomorphometric analysis, which allowed the evaluation of bone to implant contact (BIC) and the bone area fraction occupancy between the threads (BAFO). Our surface analysis data showed that the Control Group exhibited an irregular and non-homogenous topography while the Test Group showed a nanotextured surface. The Test Group showed higher wettability (contact angle = 5.1 ± 0.7°) than the Control Group (contact angle = 75.5 ± 4.6°). Concerning the histomorphometric analysis results for T1, Control and Test groups showed BIC percentages of 41.3 ± 15.2% and 63.1 ± 8.7% (p < 0.05), respectively, and for BAFO, 28.7 ± 13.7% and 54.8 ± 7.5%, respectively (p < 0.05). For T2, the histomorphometric analysis for Control and Test groups showed BIC percentages of 51.2 ± 11.4% and 64.8 ± 7.4% (p < 0.05), respectively and for BAFO, 36.4 ± 10.3% and 57.9 ± 9.3% (p < 0.05), respectively. The findings of the current study confirmed that the novel nanotextured surface exhibited superior wettability, improved peri-implant bone formation, and expedited osseointegration.

Surface characterization of nickel titanium orthodontic arch wires

BACKGROUND

Surface roughness of nickel titanium orthodontic arch wires poses several clinical challenges. Surface modification with aesthetic/metallic/non metallic materials is therefore a recent innovation, with clinical efficacy yet to be comprehensively evaluated.

METHODS

One conventional and five types of surface modified nickel titanium arch wires were surface characterized with scanning electron microscopy, energy dispersive analysis, Raman spectroscopy, Atomic force microscopy and 3D profilometry. Root mean square roughness values were analyzed by one way analysis of variance and post hoc Duncan's multiple range tests.

RESULTS

Study groups demonstrated considerable reduction in roughness values from conventional in a material specific pattern: Group I; conventional (578.56 nm) > Group V; Teflon (365.33 nm) > Group III; nitride (301.51 nm) > Group VI (i); rhodium (290.64 nm) > Group VI (ii); silver (252.22 nm) > Group IV; titanium (229.51 nm) > Group II; resin (158.60 nm). It also showed the defects with aesthetic (resin/Teflon) and nitride surfaces and smooth topography achieved with metals; titanium/silver/rhodium.

CONCLUSIONS

Resin, Teflon, titanium, silver, rhodium and nitrides were effective in decreasing surface roughness of nickel titanium arch wires albeit; certain flaws. Findings have clinical implications, considering their potential in lessening biofilm adhesion, reducing friction, improving corrosion resistance and preventing nickel leach and allergic reactions.

Osteoconductive Potential of Mesoporous Titania Implant Surfaces Loaded with Magnesium: An Experimental Study in the Rabbit

BACKGROUND

Mesoporous coatings enable incorporation of functional substances and sustainedly release them at the implant site. One bioactive substance that can be incorporated in mesoporous is magnesium, which is strongly involved in bone metabolism and in osteoblast interaction.

PURPOSE

The aim of this experimental study was to evaluate the effect of incorporation of magnesium into mesoporous coatings of oral implants on early stages of osseointegration.

MATERIAL AND METHODS

Titanium implants were coated with thin films of mesoporous TiO2 having pore diameters of 6 nm and were loaded with magnesium. The implant surfaces were extensively characterized by means of interferometry, atomic force microscopy, scanning electron microscopy, and energy-dispersive spectroscopy and then placed in the tibiae of 10 rabbits. After 3 weeks of healing, osseointegration was evaluated by means of removal torque testing and histology and histomorphometry.

RESULTS

Histological and biomechanical analyses revealed no side effects and successful osseointegration of the implants. The biomechanical evaluation evidenced a significant effect of magnesium doping on strengthening the implant-bone interface.

CONCLUSIONS

A local release of magnesium from the implant surfaces enhances implant retention at the early stage of healing (3 weeks after implantation), which is highly desirable for early loading of the implant.

Clinical and histomorphometrical study on titanium dioxide-coated external fixation pins

Background:

Pin site infection is the most common and significant complication of external fixation. In this work, the efficacy of pins coated with titanium dioxide (TiO₂) for inhibition of infection was compared with that of stainless steel control pins in an in vivo study.

Methods:

Pins contaminated with an identifiable Staphylococcus aureus strain were inserted into femoral bone in a rat model and exposed to ultraviolet A light for 30 minutes. On day 14, the animals were sacrificed and the bone and soft tissue around the pin were retrieved. The clinical findings and histological findings were evaluated in 60 samples.

Results:

Clinical signs of infection were present in 76.7% of untreated pins, but in only 36.7% of TiO₂-coated pins. The histological bone infection score and planimetric rate of occupation for bacterial colonies and neutrophils in the TiO₂-coated pin group were lower than those in the control group. The bone-implant contact ratio of the TiO₂-coated pin group was significantly higher (71.4%) than in the control pin group (58.2%). The TiO₂ was successful in decreasing infection both clinically and histomorphometrically.

Conclusion:

The photocatalytic bactericidal effect of TiO₂ is thought to be useful for inhibiting pin site infection after external fixation.

Accelerated bone formation on photo-induced hydrophilic titanium implants: an experimental study in the dog mandible

OBJECTIVES

The purpose of this study was to investigate the effect of photo-induced hydrophilic titanium dioxide (TiO₂) on serum fibronectin (sFN) attachment, and further to evaluate initial osseointegration responses in the dog mandibles.

MATERIALS AND METHODS

To apply the anatase TiO₂ film, plasma source ion implantation (PSII) method followed by annealing was employed for the titanium disks and implants, which were then illuminated with UV-A for 24 h for the experimental groups. Non-deposited titanium disks and implants were prepared for the control group. Surface characterization was performed using the interferometer and contact angle analyzer. The attachments of sFN were evaluated using fluorescence emission analysis. Thereafter both groups of implants were placed in the mandible of six beagle dogs. Bone response was investigated with histological and histomorphometrical analyses after periods of 2 and 4 weeks.

RESULTS

The experimental groups exhibited strong hydrophilicity under UV-A illumination and showed significant improvement in sFN attachment. And further, the experimental implants enhanced the bone formation with the bone-to-implant contact of 42.7% after 2 weeks of healing (control: 28.4%).

CONCLUSIONS

The combined applications of plasma fibronectin and PSII to produce hydrophilic titanium surfaces could accelerate early osseointegration.

Thickness and surface structure of a ceramic layer created on three indirect resin composites with aerosol deposition

PURPOSE

Aerosol deposition is a technology for coating ceramics with impact consolidation at room temperature. The aim of the present study was to investigate the thickness and the microstructure of the aluminium oxide layer on different three dental resin composite materials created by means of aerosol deposition.

METHODS

Disk-shaped specimens were fabricated with three resin composites (Estenia C&B, Targis, and Gradia). The specimens were ground flat, and then subjected to aerosol deposition using aluminium oxide submicron particles without inducing a localized temperature rise. The average thickness (AVH) and maximum thickness (Hmax) of the aluminium oxide layer deposited on the resin composite material were measured using a profilometer. Data were analyzed by ANOVA and post hoc Tukey compromise test at α=0.05. The specimen surfaces were also observed using a scanning electron microscope.

RESULTS

The aluminium oxide layer formed on Estenia C&B (AVH 8.1 μm, Hmax 9.1 μm) and Targis (AVH 7.7 μm, Hmax 8.9 μm) were significantly thicker than that on Gradia (AVH 4.2 μm, Hmax 5.4 μm). The micrograph showed that the aluminium oxide layer on Estenia C&B was similar to that on Targis. However, the aerosol deposition area of Gradia was seen relatively rough and partly caved.

CONCLUSIONS

The type of resin composite affected the microstructure of the deposited aluminium oxide layer. The highly filled light- and heat-cured resin composites are advantageous as a target material rather than the lower filled light-cured resin composite.

Bone response of Mg ion-implanted clinical implants with the plasma source ion implantation method

OBJECTIVES

This study examined the bone response of magnesium (Mg) ion-implanted implants produced using a plasma source ion implantation method.

MATERIALS AND METHODS

The surface characteristics were evaluated by scanning electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy, and Rutherford backscattering spectroscopy. The screw-type titanium implants were treated with resorbable blasting media (RBM) and divided into one control group (RBM implants) and three test groups (Mg ion-implanted implants with different retained Mg doses). Twenty-four implants from each group were placed into the tibiae of 24 New Zealand white rabbits. After allowing 6 weeks for healing, the removal torque (RTQ) was measured and the implants were subjected to histomorphometric analysis.

RESULTS

The surface roughness and surface morphology of the test groups were similar. The Mg ion-implanted implants with a 2.3 x 10(15) ions/cm(2) retained dose showed a significantly higher RTQ than the other implants. Histomorphometric analysis indicated that the bone contact of this group was superior to the other groups.

CONCLUSION

The bone response of Mg ion-implanted implant showed results superior or similar to an RBM-treated implant. The optimal Mg ion concentration that induced the strongest osseointegration was approximately 9%.

Saliva and dental implants

This is a review and update of the: (1) interaction of dental implants with the environment, and (2) effects of salivary contamination on the load of implant prostheses.

Effect of Ceramic Coating by Aerosol Deposition on Abrasion Resistance of a Resin Composite Material

Aerosol deposition (AD coating) is a novel technique to coat solid substances with a ceramic film. The purpose of the present study was to investigate the effect of AD coating on abrasion resistance of a resin composite material. A 5-microm-thick aluminum oxide layer was created on the polymerized resin composite. The specimen was cyclically abraded using a toothbrush abrasion simulator for 100,000 cycles. Abraded surface was then measured with a profilometer to determine the average roughness (Ra) and maximum roughness (Rmax). It was found that abrasion cycling increased the Ra value of the No-AD-coating group, but decreased the Ra and Rmax values of the AD coating group. Moreover, the AD coating group showed significantly smaller Ra and Rmax values after 100,000 abrasion cycles as compared to the No-coating control group. Microscopic observation supported these findings. In conclusion, the resistance of the resin composite against toothbrush abrasion was improved by AD coating.

An Antibacterial Surface on Dental Implants, Based on the Photocatalytic Bactericidal Effect

BACKGROUND

It is well known that the moderately roughened surfaces of dental implants enhance direct bone-implant contact. However, rough implant surfaces, as compared to smooth surfaces, are thought to pose a higher risk of bacterial infection when exposed to the oral cavity.

PURPOSE

This study was focused on evaluating the photocatalytic bactericidal effects of anatase titanium dioxide (TiO(2)) on gram-negative anaerobic bacteria known to be associated with periimplantitis.

MATERIALS AND METHODS

A film of photocatalytic anatase TiO(2) was added onto the surface of commercially pure titanium disks by plasma source ion implantation (PSII) followed by annealing. The photocatalytic properties of the film were confirmed by the degradation of methylene blue. Actinobacillus actinomycetemcomitans and Fusobacterium nucleatum cells were incubated anaerobically and seeded on the disk. The disks were then exposed to ultraviolet A (UVA) illumination from black light in an anaerobic environment. After illumination, the number of viable cells was counted in terms of colony-forming units.

RESULTS

The anatase TiO(2) film added by the PSII method and annealing exhibited a strong photocatalytic reaction under UVA illumination. The viability of both types of bacteria on the photocatalytic TiO(2) film was suppressed to less than 1% under UVA illumination within 120 minutes.

CONCLUSION

The bactericidal effect of the TiO(2) photocatalyst is of great use for sterilizing the contaminated surface of dental implants.

Changes in the surface oxide composition of Co–Cr–Mo implant alloy by macrophage cells and their released reactive chemical species

We hypothesized in this study that macrophage cells and their released reactive chemical species (RCS) alter the surface oxide composition of Co-Cr-Mo alloys in vitro. Alloys were prepared to simulate the clinical conditions and incubated for 3 days in cell culture medium, medium with macrophage cells and medium with activated macrophage cells. X-ray photoelectron spectroscopy was used to evaluate the elemental and chemical changes of the surface oxide compositions. The as-polished and passivated specimens exhibited typical Cr(2)O(3) rich surfaces. After 3 days in medium, the major metal peaks were masked by proteins from the culture medium, as indicated by the increase in N and C peaks. When cultured with cells, the Cr peaks reappeared and the O peak increased in intensity. These peak intensities increased further when the cells were activated to release NO and other RCS. We speculated that the cells reduced protein depositions and RCS may have enhanced alloy surface oxides through the oxidation and nitration reactions. These data have demonstrated that surface oxide composition varied with in vitro environments. Changes in the composition of the alloy surface oxides over time by cells are important to the understanding of host-material interactions and in the release of alloy corrosion products.

In vitro biocorrosion of Ti-6Al-4V implant alloy by a mouse macrophage cell line

Corrosion of implant alloys releasing metal ions has the potential to cause adverse tissue reactions and implant failure. We hypothesized that macrophage cells and their released reactive chemical species (RCS) affect the alloy's corrosion properties. A custom cell culture corrosion box was used to evaluate how cell culture medium, macrophage cells and RCS altered the Ti-6Al-4V corrosion behaviors in 72 h and how corrosion products affected the cells. There was no difference in the charge transfer in the presence (75.2 +/- 17.7 mC) and absence (62.3 +/- 18.8 mC) of cells. The alloy had the lowest charge transfer (28.2 +/- 4.1 mC) and metal ion release (Ti < 10 ppb, V < 2 ppb) with activated cells (releasing RCS) compared with the other two conditions. This was attributed to an enhancement of the surface oxides by RCS. Metal ion release was very low (Ti < 20 ppb, V < 10 ppb) with nonactivated cells and did not change cell morphology, viability, and NO and ATP release compared with controls. However, IL-1beta released from the activated cells and the proliferation of nonactivated cells were greater on the alloy than the controls. In summary, macrophage cells and RCS reduced the corrosion of Ti-6Al-4V alloys as hypothesized. These data are important in understanding host tissue-material interactions.