Group IV-B of the periodic table possesses two of the most frequently used elements in the field of biomaterials in the form of dental and orthopedic implants namely Titanium (Ti) and Zirconium (Zr). Both of these materials show similar chemical and mechanical properties. Zr and its alloys manifest several properties including enhanced corrosion resistance against acidic, alkaline, or organic solutions, excellent mechanical properties1,2), improved chemical stability3), low cytotoxicity, excellent flexural strength, fracture resistance4), less heat conductivity and elastic modulus. These properties portray it as a perfect replacement for hard tissue and bone in the form of orthopedic and dental implants5,6). However, Zr has some properties including decreased magnetic permeability and dissolution of the calcium phosphate layer in a simulated body fluid (SBF) which further explains its uniqueness7,8). It is best suited for magnetic resonance imaging (MRI) during orthopedic and neurosurgery9). Addi-tionally, the elastic modulus of the zirconia implants is 92 GPa (nearer to the human bone) allowing it to divide the mechanical burden lowering the stress shielding of the bone. It results in decreased bone atrophy and improved bone healing and remodeling10).
This development of a native oxide encasing on Zirconium's surface is attributed to its biocompatibility and exceptional resistance to corrosion. This native oxide (zirconia, ZrO2) layer, on the other hand, is classified as bio-inert11), which limits the chemical linkage between the bone tissue and the implant material. This might be a disadvantage because rapid bonding of biomaterial with bone is desirable for most implant applications. Also, pitting corrosion has been observed at decreased potentials in SBF12). As an outcome, the degree of corrosion rises, potentially reducing the biological efficiency and longevity of the Zr implant. Consequently, proper surface modification is essential to increase Zirconium's bioactivity and corrosion resistance while maintaining its biocompatibility in the body fluids environment. However, in low-temperature and humid environment, zirconia undergoes low-temperature aging, which alters its mechanical characteristics by changing from a slightly stable tetragonal phase to a monoclinic phase (Fig. 1)13-15).
Figure 1. Crystal Structures of ZrO2: Tetragonal and monoclinic. Blue and Red spheres represents zirconium and oxygen atoms, respectively17).
ZrO2 and hydroxyapatite (HA) are applied to Zr-based surfaces to increase their biological activity. As a result, the oxide-based phases on Zr give bioactivity that considerably aids osseointegration16,17). One of the significant factors of cell adhesion includes Arginine–glycine–aspartate (Arg–Gly–Asp or RGD) tripeptides present in the extracellular matrix. According to Hsu et al., RGD peptide could be effectively coated onto zirconia surfaces as a chemically bonded coating that is both resilient and operational and also assists in enhancing osteogenesis, improving the per-mucosal sealing, and acts as an antimicrobial18). Additionally, Al2O3/ZrO2 composite coatings and Polydopamine (PDA) coatings also have a prominent role in cell adhesion, spreading, and proliferation, along with wear resistance, corrosion resistance, and decreased heat conductivity11,19,20). Different surface modification techniques have been implemented to upgrade the contacting surface to enhance the process of osseointegration and develop a rapid bond between the tissue and the implant material. The most commonly applied methods for surface modification are categorized into three classes including physical (sandblasting, plasma spraying, ion implantation, laser treatment, and pulsed magnetron sputtering), chemical (acid etching, anodizing, and micro-arc oxidation), and biological (protein absorption and ion interaction)21-24).
Micro-arc oxidation (MAO, also named plasma electrolytic oxidation or anodic spark oxidation) has been demonstrated as a quite rapid and straightforward approach for preparing operational ceramic layers such as anti-corrosion coatings, anti-wear coatings, or bioactive coatings on valve metals (such as Al, Mg, Ti, and Zr)25). One of its unique qualities is versatility. Among these approaches, MAO appears to be better than the others due to its ease of processing and manufacturing bioactive layers that are extremely porous, crystalline, relatively rough, and adhesive on the basic metals/alloys. A significant volume of study has been conducted on the MAO of Zr and Zr-alloys and biocompatibility improvements have been documented in the last few years26,27). With the help of MAO, a Calcium (Ca) and Phosphate (P) layer could be formed on the zirconium implant surface, which is an important component of the hydroxyapatite (HA) with less solubility and resorption28). It simultaneously modifies the physical and chemical characteristics of the substrate. Intrinsic factors including the composition, concentration, and pH of the electrolyte as well as the extrinsic parameters like electric voltage, electrolyte temperature, and duration of the process significantly affect the micro molecular structure and width of the oxide coatings29). Among the parameters mentioned above, electrolyte composition, and concentration have a key role in producing coatings with a certain chemical structure and microscopic structure by incorporating different cations and anions which eventually get into the oxide layer and result in regulating the properties of the final coated layer such as the kind and dimension distribution of the pores, the phases contained in the coating, as well as its erosion, deterioration, and biological qualities30-32). As mentioned above, Zr possesses a bio inert nature which can regress its biocompatibility characteristic. MAO surface modifications enhance corrosion resistance, surface roughness, and bioactivity, which significantly increases integration of Zr with the bone. As pictorial representation of the MAO process is presented in Fig. 233).
Figure 2. Schematic depiction of the MAO experiment (photo of a 2024 aluminum alloy undergoing MAO at 15-minute processing time)34).
Currently, there is a lack of comprehensive knowledge on practical methods to modify the pure Zr following improved biocompatibility and corrosion resistance. There is a low frequency in the articles indicating the improved Osseo integrative and bioactive psroperties in the last decade. This systematic review hypothesized that MAO-modified Zirconium implants have an increasing impact on the physical and chemical properties of pure Zr. The objective of the current systematic review includes supporting the present hypothesis and extensively authenticating the effectiveness of MAO-modified Zr implants on augmenting Bioactivity, corrosion resistance, and related properties.
This systematic review was conducted as mentioned by the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) quotes34). The selection of relevant research articles exclusively in-vitro studies has been done under the constructed hypothesis as mentioned in the population, intervention, comparison, and outcomes (PICO) principle, as shown in Table 1.
Table 1 . PICO Model
| Participants | Pure Zr or Zr-based alloy samples |
Different Medical Subject Headings (MeSH) terms obtained from titles have been used in the search strategy as seen in Table 2. Also, Boolean operators, including 'AND,' 'OR,' and 'NOT,' are used to speed up the search process effectively. 'AND' was preferably used between 'Zirconium implants,' 'Microarc oxidation,' Plasma Elec-trolytic Oxidation,' Surface modifications,' Biocom-patibility,' 'modified surfaces,' and 'fixed prosthesis.' To extend the search process further, 'OR' has been used to differentiate between 'Zirconia (Zr) implants' and 'Zr-based alloy implants', 'Plasma Electrolytic Oxidation' and 'Microarc oxidation,' 'Biocompatibility' and 'Bioactivity,' 'Surface modifications,' and 'Surface treatments.' To exclude studies including only modified zirconium implants by micro-arc oxidation, 'NOT' was operated on.
Table 2 . Keywords for search strategy
| Sr. no | Search strategy |
|---|---|
| 1 | Zirconia implants [Abstract & Keywords] OR Dental implants [MeSH] OR Biocompatibility [MeSH ] OR In-vivo [MeSH] OR Micro-arc oxidation [Abstract & Keywords] OR Plasma Electrolytic Oxidation[Abstract & Keywords] OR Surface modifications [Abstract & Keywords] |
| 2 | Biocompatibility [MeSH] OR Zirconia implants [tw] OR Surface modifications [tw] OR Dental implants [MeSH] OR Plasma Electrolytic Oxidation [tw] OR Corrosion resistance [tw] OR In-vivo [MeSH] OR Bioactivity [MeSH] OR Micro-arc oxidation [tw] |
| 3 | Dental implants [MeSH] OR Biocompatibility [MeSH] OR Zirconia implants [Abstract & Keywords] OR Surface modifications [Abstract & Keywords] OR Plasma Electrolytic Oxidation [Abstract & Keywords] OR Micro-arc oxidation [tw] |
Pub-Med, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) were the databases and search engines incorporated for the selection of studies systematically. The search process has been refined through selective filtration. Original articles from in-vitro studies published from January 2010 to April 2024 were selected. These studies were analyzed critically to collect relevant data and information on the impacts of MAO modification of Zr implants. Studies focused on the laboratory experiments on the surface modification of Zr implants through the MAO process. The search process was simplified using the PICO model and enhancing its results (Table 1).
Published studies between January 2010 to April 2024 were selected for this review. The included in-vitro studies examined the alteration in the bioactivity of coated Zr implants. Studies have applied Micro-arc oxidation technique for modifications of zirconium implants. These studies have been published in English. Included studies were the original articles reporting in-vitro experiments. The selected studies assessed the integration of Zr by using different parameters including Corrosion Resistance, Biocompatibility, Bioactivity, Apatite attachment ability, Microhardness, and Cell adhesion.
Studies with improper data and its analysis, incompatibility with results, and conflicting titles have been rejected. The studies published in any language other than English were also not selected. Some studies show restrictions while accessing their full text, which leads to their exclusion. Also, unpublished data from the thesis and dissertation were excluded during the literature search. Review articles, case reports, retrospective studies, clinical studies, and letters to the editor, personal opinions, guidelines, surveys, conferences and in vivo animal studies have also been excluded during the literature search.
This study was designed based on the IMRAD outline, as it has provided a complete and comprehensive platform for research presentation35). It highlights the research question well and promotes the data, analysis, and findings along with clinical relevance, which would be helpful in future studies. The introduction comprises a discussion of the title topic; the methodology declares how the research is performed, and data interpretation and the conclusion are shown in the result and discussion part35,36).
Following the PICO approach, the two authors (SAA and YA) carefully examined and chose to study’s selecteion (Table 1). The investigators retrieved and classified by population, research category, redundant information, whole text documents, and empirical research by utilizing Microsoft Excel and a predefined data extraction form, making the systematic review technique achievable. Variable data comprises the author, year of publication, Sample composition, electrolyte, component of coating, details of MAO procedure, and study methodologies. The investigators by working independently, evaluated the included studies' quality and the potential for bias. This was accomplished by using a protocol that was modified from the QUIN tool created by Sheth et al.37), taking into account the following factors: precisely defined objectives, an explanation of the sample size calculation, the existence of a well-defined control group, operator blinding, the quantity of links utilised, the distance between pins, and statistical analysis. The two Researchers (SAA and YA) awarded scores for each of the criteria: 2 for sufficiently specified, 1 for badly stated, and 0 for not specified.
Databases such as Google Scholar, Pub-Med, ELSEVIER, SAGE, and the Cochrane Central Register of Controlled Trials led to 654 papers. The research articles have been organized based on their keywords and text terms. According to PRISMA regulations, 393 studies were removed after screening for identical and ineligible research, as shown in Fig. 3. 261 records were further screened of which 184 were excluded due to non-relevant content. 77 records were sought for retrieval and 18 of them have been retrieved successfully. Finally, 9 studies were selected and the rest of them were excluded due to reasons mentioned in Fig. 3. Table 3 contains information about eligible research. Conclusively, the selected research studies investigated the impacts of MAO surface modification of Zr implants.
Table 3 . Characteristics of the included studies
| Author/Ye | MAO process | Study type | Control/Reference material | Parameters assessed | ||
|---|---|---|---|---|---|---|
| Sample | Electrolyte | Main components | ||||
| Shao-Fu Lu (2015)41) | Pure Zr specimens (10 mm×8 mm×2.0 mm) | 0.1 M K3PO4 with varying concentrations of KOH (0.01, 0.05, and, 0.1 M) | O (<67.3%), Zr (<35.7%), K (<0.2%), and P (>0.1%) | In-vitro | Pure Zr plate | Wettability, cell-material interaction biocompatibility, Cell morphology and adhesion, Corrosion Resistance |
| Zheng-yang Li (2021)40) | Zr alloy (1.0% Nb, 1.0% Sn, 0.3% Fe, and Zr balance) | 15 gL− 1 Na2SiO3 + 3 gL− 1 NaF + 15 gL−1 KOH along with Four different nanoparticles Al2O3, MoS2, CeO2, and GO with a concentration of 0.1 gL− 1. | Four different MAO coatings | In-vitro | - | Film hardness, Corrosion resistance |
| Salih Durdu (2017)38) | Pure zirconium samples (30 mm×25 mm×5 mm) | 0.25 M Calcium acetate and 0.06 M β-glycerophosphate disodium salt. | Ca K, P K, and O K | In-vitro | - | Biocompatibility and antimicrobial property |
| Jung-Yun Ha (2011)3) | Pure Zr discs (12.7 mm×1.5 mm) | 0.1 mol L−1 calcium glycerophosphate and 0.15 mol L−1 magnesium acetate. | Ca, P, and Mg | In-vitro | - | Bioactivity |
| Sezgin Cengiz (2016)45) | Pure zirconium samples (50 mm×25 mm×0.7 mm) | 12 g/l Na2SiO3 ×5H2O, 8 g/l Ca (CH3COO)2×H2O, 8.5 g/l C3H7Na2O6P×5H2O solution | Ca2+ and PO4 3− | In-vitro | - | Apatite attachment ability |
| S. Fidan (2016)39) | Zr samples (9 mm×5 mm) | 15 g/L sodium silicate (NaSiO3) and 2 g/L sodium hydroxide (NaOH) | Si, Zr, O, Na, and Ag | In-vitro | Base Zr and MAO coated ZR with Ag | Bactericidal activity |
| Yuanyuan Yan (2010)25) | Pure Zr discs (15 mm×5 mm) | NaAlO2 solution | Zr, Al, O, and C. | In-vitro | - | Microhardness and Corrosion resistance |
| Sandhyarani M (2014)42) | Pure zirconium samples (20 mm×15 mm×1.5 mm) | Five different electrolyte solutions are composed of varied concentrations of tri-sodium orthophosphate, sodium meta silicate, and potassium hydroxide. | O, Zr, Na, K, Si, and P. | In-vitro | - | Corrosion resistance, Cell adhesion, and Bioactivity. |
| M. Sandhyarani (2013)43) | Pure zirconium samples (20 mm×15 mm×1.5 mm) | 5 g/L of tri-sodium orthophosphate | Zr, O, and P. | In-vitro | - | Corrosion resistance, Bioactivity |
Figure 3. PRISMA flow diagram of article selection process37).
According to the risk of bias assessment, no research examined unambiguously documented sequence lineage, assignment concealment, random sampling, or carer and investigator masking. Additionally, there were no indications of publication bias. According to the Quality assessment through QUIN tool as mentioned in Table 3, details regarding sample size calculation, operator and blinding of experiement has been missing from the included studies. Elaboration of randomization and comparison groups has also been observed to be a less frequent reported criteria. Only a few studies has left the details regarding sampling technique. Aims and objectives of the research, methodological explanation, outcome measurement, result details, statistical analysis, and presentation of the results have been frequently reported in the included studies. Study conducted by Sandhyarani M (2014) has the highest score among of 17 followed by M. Sandhyarani (2013) with a score of 16. Zheng-yang Li (2021) and Jung-Yun Ha have the lowest scores of 12 among all the studies.
All the included studies conducted in-vitro experiments on pure Zr samples to modify their surfaces. There was variance in the methodologies used by different articles, as well as divergences in the measuring of outcomes. Therefore, As a result, ultimately qualitative descriptive assessments of the studies mentioned in Table 4 are presented here. Among these in-vitro studies, two of them evaluates antimicrobial property after coating Zr samples through the MAO process38,39). One of the studies used Zr alloy (1.0% Nb, 1.0% Sn, 0.3% Fe, and Zr balance) for the surface modification40) while the rest of the used pure Zr samples of different dimensions. According to the literature review, only two studies used reference material for the control group including pure Zr plate41) and Base Zr and MAO-coated Zr with Ag39). K3PO4 was employed by Shao-Fu Lu (2015) at different KOH concentrations. Zheng-yang Li (2021) mixed several nanoparticles (Al2O3, MoS3, CeO3, and GO) with a combination of Na3SiO3, NaF, and KOH. A solution of magnesium acetate and calcium glycerophosphate was utilized by Jung-Yun Ha (2011). Two studies measure the microhardness of the MAO-coated Zr samples through Vickers microhardness tester25,40). Wettability is measured in only one study41). Furthermore, biocompatibility and bioactivity3,38,41-43), cell adhesion and morphology39,40), and corrosion resistance25,40-43) have also been evaluated after modifying pure Zr surface through MAO process. There is an increased corrosion resistance observed by Shao-Fu Lu (2015), Zheng-yang Li (2021), Yuanyuan Yan (2010), Sandhyarani M (2014), and M. Sandhyarani (2013). Moreover, an increased biocompatinility has been observed by the Shao-Fu Lu (2015), Salih Durdu (2017), Jung-Yun Ha (2011), Sandhyarani M (2014), and M. Sandhyarani (2013). These findings showed that the proposed hypothesis is correct that the MAO-modified Zirconium implants have an increasing impact on the physical and chemical properties of pure Zr.
Table 4 . Quality of the included studies using the QUIN tool37)
| Criteria no. | Criteria | Shao-Fu Lu (2015)41) | Zheng-yang Li (2021)40) | Salih Durdu (2017)38) | Jung-Yun Ha (2011)3) | Sezgin Cengiz (2016)45) | S. Fidan (2016)39) | Yuanyuan Yan (2010)25) | Sandhyarani M (2014)42) | M. Sandhyarani (2013)43) |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Clearly stated aims/ Objectives | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| 2 | Detailed explanation of sample size calculator | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 3 | Detailed explanation of sampling technique | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 |
| 4 | Details of comparison group | 1 | 0 | 2 | 0 | 1 | 1 | 1 | 2 | 1 |
| 5 | Detailed explanation of methodology | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| 6 | Operator details | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 7 | Randomization | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 |
| 8 | Method of measurement of outcome | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| 9 | Outcome assessor details | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| 10 | Blinding | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 11 | Statistical analysis | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| 12 | Presentation of results | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| Total | 13 | 12 | 15 | 12 | 14 | 14 | 14 | 17 | 16 |
2: adequately specified, 1: inadequately specified, 0: not specified.
Tailoring the outer surface of the implants is a common practice today which disclosed a series of in-vitro, in-vivo studies, and clinical trials. Although, there has been a low number of articles and clinical trials have been published within the last few decades despite its invaluable advantages and worldwide application of Zr metal as an implant abutment in dentistry and orthopedics. The only major drawback is the bio-inertness of pure Zr which leads to poor osteointegration and implant failure. To overcome this problem, surface modification has been implied and proved to be a permanent solution for this failure by enhancing the osteogenesis ability along with the corrosion resistance20,21). The investigators have used different procedures to produce coatings on the metallic implants. Micro-arc oxidation has gained popularity in the last decade to be one of the most cost-effective, efficient, and eco-friendly procedures that could produce a functional oxide layer on the Ti, Mg, and Al implants44). The results of the selected studies have been reported in a systematic manner and evaluated based on hypothesized outcomes.
The characteristic morphology and chemical composition of the oxide layers could explain its remarkable wettability, biocompatibility, and corrosion resistance. Shao-Fu Lu et al (2015)., indicated an outstanding observation in the bioactivity around the ZrO2 coated implants with no sign of toxicity to both 3T3 and MG63 cells along with better corrosion resistance to Hank’s solution41). The oxide layer is a porous layer with an inner dense and outer more permeable. These composite ZrO2 layers have been observed to be more effective in controlling corrosion rate than the pure Zr alloy because of its more dense structure. Also, due to less shear stress between the coated layers, they would reduce the friction by gliding on one another and eventually lowering the wear ratio40). Durdu et al (2017)., further modified the oxide layer by adding an anti-microbial Ag through the MAO process. It has not only increased the anti-bacterial activity in the peri-implant area but also increased the bioactivity38). Another study conducted by Fidan et al (2016)., also incorporated nanoparticles composed of Ag on pure Zr through MAO. The results showed a decreased antibacterial activity specifically against Methi-cillin-resistant Staphylococcus aureus (MRSA) which is one of the main reasons for implant failures by infecting per-implant tissue39).
Bioactivity is enhanced in the presence of an oxide layer less than the toxic limit. Jung-Yun Ha et al (2011)., applied both the MAO technique and the chemical treatment of the pure Zr metal with a thick hydroxyapatite crystal layer on it. This modification improved the bioactivity along with the addition of any of the suitable elements including Mg into the oxide layer3). Yan et al (2010)., modified the Al2O3/ZrO2 composite layers by incorporating the NaAlO2 concentrations varied from 0.2M to 0.3M. this makes the oxide layer more dense and strong with an increased bond strength, film hardness, and corrosion resistance. Likely, the higher concentration of NaAlO2 i.e. more than 0.35M could be hazardous to the cell morphology and properties of the MAO layer25). According to Sandhyarani M et al (2014)., all of the MAO layers produce a higher corrosion-resistant property and increased apatite adhesion quality as compared to the pure Zr. Moreover, layers produced in the silicate-based electrolyte presented better cell adhesion and differentiation along with superior wettability42). FTIR analysis revealed the existence of a non-crystalline initial apatite production through the MAO method, as well as additional HA crystal development when SBF was added to this layer. The presence of characteristic MAO features such as voids, splits, and discharge pathways, as well as significant surface roughness with a changed surface chemical structure on the covered surface, encouraged secondary apatite formation on the exterior surface45). According to the results of the study conducted by M. Sandhyarani et al (2013)., the inclusion of P molecules in the oxide coating significantly increased Zr bioactivity along with good corrosion resistance and bioactivity and will be a promising material for orthopedic implants.
A surface modification method called micro-arc oxidation (MAO) is frequently used to improve the characteristics of materials like zirconium (Zr), especially in biomedical applications45). In contrast to other methods of surface modification like anodization and plasma spraying, MAO has unique benefits and drawbacks. MAO produces thicker, more porous oxide layers than anodization, which greatly enhance bioactivity and increase cell adhesion. Moreover, it produces a tougher surface that improves mechanical stability and wear resistance. In contrast to anodization, MAO promotes better osseointegration by enabling the addition of bioactive components like calcium (Ca) and phosphorus (P)46). Nevertheless, MAO is a more involved and energy-intensive procedure that frequently produces surfaces that are rougher and might not be appropriate for uses that call for a smooth finish. Whereas coatings sprayed with plasma may have lower adherence and maybe delamination, MAO offers a robust integrated oxide layer on the substrate surface. MAO also improves tissue integration and bioactivity by forming more homogeneous coatings with regulated porosity. However, plasma spraying can deposit a larger range of materials, including hydroxyapatite, which is advantageous for dental implants, and allows for thicker coatings, which may be required in some applications47).
To include as many relevant articles as possible, this systematic review used a broad search technique rather than relying just on titles and abstracts. The main limitation is the inclusion of all the in-vitro studies, as there could be some parameters that would change by shifting the environment within a living organism. Access to different in-vivo investigations contributes to better confidence in addressing the topic raised in this review. The lack of a total effect of MAO-coated oxide layers on biocompatibility and corrosion resistance has also been observed. However due to the range of experimental settings, mixing methodologies, and cell lines investigated, managing a meta-analysis would not be possible. Although because of the reduced number of in-vivo studies and clinical trials of MAO-coated Zr implants, in the future, it could be conducted purely based on in-vivo studies to evaluate the performance of surface modification more accurately. Zr's inert nature prevents it from osseointegrating with bone. The Zr implant's biochemical characteristics would be improved if its exterior were modified with a biocompatible substance. To make it more resilient, it will accelerate osseointegration and boost corrosion resistance.
Each of the selected studies possessed good quality and scientifically presented results. Outcome measures have been evaluated according to every study’s result and reported systematically. After a dense literature review, a total of 9 in-vitro studies concluded that the ZrO2-coated specimens showed negligible cytotoxicity, a high rate of cell survival, and great biocompatibility. Also, the ZrO2-coated implant in conjunction with the bone demonstrated increased fracture resistance and the capacity to generate new bone quickly. Anti-bacterial properties and corrosion resistance have also been improved by the Ag-based oxide layers via the MAO process on pure Zr. This will enhance the osseonintegration of Zr with bone. However, clinical trials are necessary to make this useful technique available for the patients.
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