Osseointegration of zirconia implants compared with titanium: an in vivo study

Mechanical behavior of titanium and zirconia abutments at the implant-abutment interface: A systematic review

STATEMENT OF PROBLEM

Zirconia has become popular for dental implant abutments in the esthetic zone but can damage the implant connection interface. Studies have been conducted to compare zirconia abutments with conventional titanium abutments; however, a consensus or systematic review is lacking.

PURPOSE

The purpose of this systematic review was to evaluate the performance of abutments made of zirconia and titanium in relation to wear and misfit at the implant-abutment interface.

MATERIAL AND METHODS

Electronic databases (PubMed/MEDLINE, Embase, Web of Science) were independently searched by 2 researchers for relevant studies published up to June 2021. The population, intervention, comparison, outcome (PICO) question was "Do zirconia abutments cause greater wear at the implant-abutment interface than titanium abutments under occlusal forces?" Eligible studies included in vitro studies that evaluated changes in the surface of external and/or internal connections and single and/or multiple, screwed and/or cemented prostheses rehabilitated with titanium and zirconia abutments submitted to mechanical cycling.

RESULTS

Nine studies were included for qualitative analysis. A total of 172 specimens were analyzed, 86 zirconia and 86 titanium abutments. In terms of wear on the implant connection surface, zirconia abutments caused more severe wear, more scratches, and more rounding of the hexagonal angles at the implant connection interface than titanium abutments. In terms of misfit at the connection interface, zirconia abutments showed greater misfit than titanium abutments.

CONCLUSIONS

Zirconia abutments produce more wear at the titanium implant connection interface, titanium abutments showed better fit to the implant connection interface, and the fit can be influenced by the abutment manufacturing method.

A Mapping Review of the Pathogenesis of Peri-Implantitis: The Biofilm-Mediated Inflammation and Bone Dysregulation (BIND) Hypothesis

This mapping review highlights the need for a new paradigm in the understanding of peri-implantitis pathogenesis. The biofilm-mediated inflammation and bone dysregulation (BIND) hypothesis is proposed, focusing on the relationship between biofilm, inflammation, and bone biology. The close interactions between immune and bone cells are discussed, with multiple stable states likely existing between clinically observable definitions of peri-implant health and peri-implantitis. The framework presented aims to explain the transition from health to disease as a staged and incremental process, where multiple factors contribute to distinct steps towards a tipping point where disease is manifested clinically. These steps might be reached in different ways in different patients and may constitute highly individualised paths. Notably, factors affecting the underlying biology are identified in the pathogenesis of peri-implantitis, highlighting that disruptions to the host-microbe homeostasis at the implant-mucosa interface may not be the sole factor. An improved understanding of disease pathogenesis will allow for intervention on multiple levels and a personalised treatment approach. Further research areas are identified, such as the use of novel biomarkers to detect changes in macrophage polarisation and activation status, and bone turnover.

Clinical outcomes of zirconia implants: a systematic review and meta-analysis

PURPOSE

To assess the clinical outcomes of zirconia dental implants based on an updated systematic literature review.

METHODS

An electronic search was performed in three databases, last updated in June 2023, supplemented by hand searching. The eligibility criteria were clinical studies reporting patients rehabilitated with zirconia implants. The cumulative survival rate (CSR) of implants was calculated. A meta-analysis for marginal bone loss (MBL) under different follow-up times and a meta-regression assessing the relationship between mean MBL and follow-up were done.

RESULTS

Twenty-five studies were included (4017 implants, 2083 patients). Seven studies had follow-up longer than 60 months. 172 implants failed, after a mean of 12.0 ± 16.1 months (min-max 0.3-86.0), of which 47 early failures, and 26 due to implant fracture, the majority in narrow-diameter implants. The 10-year CSR was 95.1%. Implants with coronal part prepared by drills presented statistically significant lower survival than non-prepared implants (p < 0.001). Two-piece implants presented lower survival than one-piece implants (p = 0.017). Implants discontinued from the market presented lower survival than the commercially available ones (p < 0.001). The difference in survival was not significant between implants in maxilla and mandible (p = 0.637). The mean MBL fluctuated between 0.632 and 2.060 mm over long periods of observation (up until 132 months). There was an estimated MBL increase of 0.005 mm per additional month of follow-up.

CONCLUSION

Zirconia implants present high 10-year CSR and short-term low MBL. The review was registered in PROSPERO (CRD42022342055).

CLINICAL RELEVANCE

The clinical outcomes observed for zirconia dental implants are very promising, although these have not yet been extensively studied as titanium alloy implants.

Zirconia Facts and Perspectives for Biomaterials in Dental Implantology

Dental implantology has witnessed remarkable advancements in recent years, and zirconia has emerged as a prominent biomaterial for dental implant applications. This review explores the multifaceted aspects of zirconia, focusing on its properties, processing methods, biocompatibility, mechanical performance, and clinical applications. Over the past few decades, the most popular choice of material for dental implantology has been titanium which has been found to have the highest success rate of implant treatment. However, recently, it has been observed that zirconia might replace titanium and eventually emerge as one of the gold-standard materials of dental implants. Analysis of biomechanical sciences and biomaterial sciences provides an opportunity for the refinement of design and material notions for surgical implants. However, the most important aspect and prime concern is how tissue at the implant site responds to biomechanical disturbances caused by foreign materials. The literature revealed that zirconia has certain characteristics that make it an excellent material for implants, including biocompatibility and osseointegration which depicts positive soft tissue response with low plaque affinity as well as aesthetics owing to light transmission and color. Additionally, this review discusses the current challenges and prospects of zirconia in dental implantology as well as aims to provide dental professionals and researchers with a comprehensive understanding of zirconia's potential as a biomaterial in dental implantology. The present overview of available literature intends to highlight and explore the biological characteristics of zirconia for applications in dental implantology. However, research is urgently required to fill in gaps over time for clinical assessments of all zirconia implants, consequently, the implementation of hybrid systems (a titanium screw with a zirconia collar) has recently been suggested.

A chlorogenic acid-chitosan complex bifunctional coating for improving osteogenesis differentiation and bactericidal properties of zirconia implants

Poor osteogenesis caused by limited bioactivity and peri-implantitis caused by bacterial colonization are the main challenges affecting the use of zirconia-based materials in dental implants. Accordingly, the development of a surface treatment method with an antibacterial effect and that promotes osteogenesis without damage to cells is crucial for yttrium-stabilized tetragonal zirconia (Y-TZP) implants. Herein, we have developed a functional surface modification strategy whereby a poly (ethylene imine)/hyaluronic acid /chitosan-chlorogenic acid (PEI/HA/CGA-CS) conjugate is deposited on a zirconia surface by the layer-by-layer (LBL) technique, enhancing its osteogenic differentiation and antibacterial activities. The results showed that the PEI/HA/CGA-CS coating improved the wettability of the zirconia surface and maintained stable release of CGA. The PEI/HA/CGA-CS functional coating was found to promote early cell adhesion, proliferation, differentiation, and calcification. The results of bacterial adhesion and activity tests showed that the coating effectively inhibits the proliferation and activity of Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) without impairing the biological activity of osteoblasts. In addition, we found that the PEI/HA/CGA-CS coating enhances the osteogenesis of MC3T3-E1 cells by promoting the protein expression of Nephronectin (NPNT) and activating the Wnt/β-catenin signaling pathway. The above results are of profound significance for the practical application of zirconia-based implants. DATA AVAILABILITY: Data will be made available on request.

Zirconia Dental Implants as a Different Alternative to Titanium: A Literature Review

Aim

This article aims to provide an overview of the scientific evidence comparing zirconium dental implants with titanium implants.

Materials and Methods

A comprehensive literature review was conducted using the MEDLINE database accessed through PubMed and Scopus. The search included the keywords "dental implant," "zirconia dental implant," and "titanium dental implant" without any date restrictions.

Results

The review examined research articles focusing on the physical and chemical characteristics of titanium and zirconia dental implants. Additionally, studies investigating the strength and translucency of zirconia, as well as the osseointegration of both materials, were analyzed. However, no conclusive evidence demonstrating the superiority of either material was found in the current literature.

Conclusion

Taking into account the findings of this narrative study, no significant differences were identified between zirconium and titanium dental implants. Further scientific research is required to establish a definitive recommendation regarding the use of one material over the other.

Enhanced human periodontal ligament stem cell viability and osteogenic differentiation on two implant materials: An experimental in vitro study

Background: Surface roughness of dental implants impacts the survival of adult periodontal stem cells and rate of differentiation. This research was conducted to test how human periodontal ligament stem cells behaved on yttria stabilized tetragonal zirconia polycrystals and polyetheretherketone (PEEK) discs with different surface topographies. Methods: Discs roughening was prepared by sandblasting. Stem cells were cultivated on zirconia discs with a polished surface, PEEK discs with a polished surface, sandblasted zirconia discs and sandblasted PEEK discs. Cells viability was assessed after 24, 48, 72 hours. Scanning electron microscopy was used to examine the adherence and attachment of cells. Osteoblastic differentiation capacity was studied by checking the mineralization clusters development through alizarin red S staining and alkaline phosphatase assay. ANOVA and the Tukey post hoc test were used for the statistical analysis. Results: Polished PEEK discs showed lower cell viability, whereas roughened sandblasted zirconia and PEEK discs showed the highest proliferation rates and cell viability percent. The osteogenic differentiation was enhanced for rough surfaces in comparison to polished surfaces. Sandblasted zirconia and PEEK discs showed a markedly increased mineralized nodule development and ALP enzyme activity compared to the polished surface and control. Conclusions: Micro- topographies creation on the PEEK implant surface enhances stem cell attachment, viability, and osteogenic differentiation.

Reduced Cell Adhesion on LightPLAS-Coated Implant Surfaces in a Three-Dimensional Bioreactor System

Most implants used in trauma surgery are made of steel and remain inside the body only temporarily. The strong tissue interaction of such implants sometimes creates problems with their explantation. Modified implant surfaces, which decrease tissue attachment, might allow an easier removal and therefore a better outcome. Such a modification must retain the implant function, and needs to be biocompatible and cost-effective. Here, we used a novel VUV-light (Vacuum-Ultraviolett)-based coating technology (LightPLAS) to generate coated stainless-steel plates. The tested LightPLAS coating only had an average thickness of around 335 nm, making it unlikely to interfere with implant function. The coated plates showed good biocompatibility according to ISO 10993-5 and ISO 10993-12, and reduced cell adhesion after four different time points in a 2D cell culture system with osteoblast-like MG-63 cells. Furthermore, we could show decreased cell adhesion in our 3D cell culture system, which mimics the fluid flow above the implant materials as commonly present in the in vivo environment. This new method of surface coating could offer extended options to design implant surfaces for trauma surgery to reduce cell adhesion and implant ingrowth. This may allow for a faster removal time, resulting in shorter overall operation times, thereby reducing costs and complication rates and increasing patient wellbeing.

Evaluation of one-piece zirconia dental implants: An 8-year follow-up study

OBJECTIVES

Long-term studies of modern zirconia implants are still insufficient. This prospective 8-year follow-up study investigated one-piece zirconia implants.

MATERIALS AND METHODS

Patients who had received a one-piece zirconia dental implant (PURE ceramic implant, Institut Straumann GmbH, Basel, Switzerland) were included in this study. Next to the implant survival and success rates, the radiographic and clinical implant parameters were assessed.

RESULTS

The overall survival rate of 67 zirconia implants in 39 patients was 100%. The overall success rate was 89.6%. Around the immediate zirconia implants, the success rate was 94.7%, and around the delayed implants, 87.5%. The immediate implants showed a significantly higher bone crest compared to the delayed implants (p = 0.0120). According to the pink esthetic score, the immediate implants revealed more favorable esthetic results compared to the delayed implants after an 8-year follow-up (p = 0.0002).

CONCLUSIONS

After 8 years, the one-piece zirconia implants presented an 89.6% success rate. Regarding the timing of implantation, in individual cases, immediate implantation can have slight advantages over delayed implantation.

CLINICAL RELEVANCE

Immediate implants can also be considered for zirconia implants and should not be excluded on principle.

Clinical evaluation and patient related outcomes of one- and two-piece zirconia implants at five years of loading: A case series study

OBJECTIVE

The objective of this study was to investigate the survival and biological and mechanical complications of one-piece and two-piece zirconia implants at five years of loading.

MATERIALS AND METHODS

Consecutive patients receiving zirconia implants were studied, collecting data at five years of loading on their clinical history, peri-implant health status, mechanical complications, esthetic results, and patient related outcomes.

RESULTS

The study included 18 patients with 29 implants. The survival rate was 86% in implant-based analysis and 78% in patient-based analysis. There were no cases of peri-implantitis, but mucositis was present in 53% of implants. A mean of 4.1 ± 0.81 mm was obtained for probing depth and 1.6 ± 0.9 mm for crestal bone loss (radiographic assessment). There were no implant fractures. Major (10%) and minor (10%) prosthesis complications were observed. The esthetic outcome was moderate to almost perfect, with a high level of patient satisfaction. No significant association was found between survival rate and the presence of mucositis around one- or two-piece implants or any other study variable.

CONCLUSIONS

The survival rate is low for one- and two-piece zirconia implants. Both types of implants demonstrated a low mechanical complication rate. The incidence of periimplantitis is low but mucositis is present in 50%. Patient satisfaction related to esthetics and function is moderate to high. They represent a good option for patients requiring an alternative to titanium implants.

CLINICAL RELEVANCE

Zirconia implants appear to be an alternative to the titanium option and may be indicated for patients requiring "metal-free" restorations.

Understanding the thrust force evolution and primary stability for dental implantation – An in-vitro experimental investigation

The dental implant is challenging due to the unstable quality of the surrounding bone. This study aimed to explore the feasibility of using thrust force characteristics to identify different bone types and the influencing mechanisms of spindle speed and feed rate on primary stability of dental implants through in-vitro experiments. 13 groups of osteotomy experiments were performed on mandibles and maxillae of pigs with different bone types (I, II, and III) under different spindle speeds (600 and 800 rpm) and feed rates (20 and 60 mm/min). The thrust force evolution under different conditions was extracted and analysed to elaborate the distribution and thickness of the cortical and trabecular bone layers on different bone types. Dental implant placements were performed, and corresponding primary stabilities were obtained. Furthermore, histologic observation was conducted to reveal the bone/implant contact morphology. From the results, the amplitude and trend of thrust force show a regular variation during drilling different bone types. The highly dynamic information of thrust force can be analysed to characterise the distribution and thickness of the cortical and trabecular bone layers, hence effectively detecting different bone types. Since a lower feed rate and resulting bone temperature elevation lead to more thermal damages, primary stability decreases with the decrease of feed rate. Spindle speed has no significant effect. This study establishes a more in-depth understanding into the thrust force evolution and also provide a clinical option for reducing the complexity of bone type and drilling parameters determination in osteotomy.

Zirconia fixed dental prostheses fabricated by 3D gel deposition show higher fracture strength than conventionally milled counterparts

Zirconia restorations, which are fabricated by additive 3D gel deposition and do not require glazing like conventional restorations, were introduced as "self-glazed" zirconia restorations into dentistry. This in vitro investigation characterized the surface layer, microstructure and the fracture and aging behavior of "self-glazed" zirconia (Y-TZP_SG) three-unit fixed dental prostheses (FDP) and compared them to conventionally CAD/CAM milled and glazed controls (Y-TZP_C-FDPs). For this purpose, the FDPs were analyzed by (focused ion beam) scanning electron microscopy, laserscanning microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and a dynamic and static loading test. For the latter, half of the samples of each material group (n = 16) was subjected to 5 million cycles of thermocyclic loading (98N) in an aqueous environment in a chewing simulator. Afterwards, all FDPs were loaded to fracture. Y-TZP_SG-FDPs demonstrated a comparable elemental composition but higher surface microstructural homogeneity and fracture strength compared to Y-TZP_C-FDPs. Microstructural flaws within the FDPs' surfaces were identified as fracture origins. The high fracture strength of the Y-TZP_SG-FDPs was attributed to a finer-grained microstructure with fewer surface flaws compared to the Y-TZP_C-FDPs which showed numerous flaws in the glaze overlayer. A decrease in fracture strength after dynamic loading from 5165N to 4507N was observed for the Y-TZP_SG-FDPs, however, fracture strength remained statistically significantly above the one measured for Y-TZP_C-FDPs (before chewing simulation: 1923N; after: 2041N). Within the limits of this investigation, it can therefore be concluded that Y-TZP_SG appears to be stable for clinical application suggesting further investigations to prove clinical applicability.

Bioactive Surface of Zirconia Implant Prepared by Nano-Hydroxyapatite and Type I Collagen

Zirconia, with its excellent mechanical strength and esthetics, has a growing potential for applications in dentistry and orthopedics. However, in order for zirconia to have a high affinity with bone tissue, the bioactivity of the surface must be further increased. In order to increase the bioactivity of zirconia, research was conducted to make a porous support or to fill the porous structure with nano-hydroxyapatite (nHA). In this case, there is a risk that physically filled nHA could be released depending on the living environment. In this study, nHA and type I collagen were introduced to the zirconia surface by chemical covalent bonding to increase bioactivity and ensure safety in the body. The chemical reaction of the surface was confirmed by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy. In addition, the biological activity was evaluated by examining the cytotoxicity and bone formation ability of the modified zirconia using osteoblasts. As a result, it was found that the bioactivity of the zirconia surface was greatly improved by immobilizing nHA and type I collagen.

Cytokines Activate JAK-STAT Signaling Pathway in MG-63 Cells on Titanium and Zirconia

Although titanium has been traditionally used as the gold standard for dental implants, recent years have seen the widespread application of zirconia implants given their superiority with regards to reduced bacterial adhesion, inflammation and cellular-interaction in terms of bio-compatibility. The JAK-STAT signaling pathway plays an important role in bone remodeling and formation. The aim of the study was to investigate the activation of the JAK-STAT pathway through different cytokines in osteoblast-like cells (MG-63) on zirconia in comparison to titanium discs. IFN-γ induced the very strong activation of STAT1 protein, IFN-α activated both STAT1 and STAT3 molecules, IL-6 activated STAT3 and IL-4 induced the activation of STAT6 on both surfaces. The activation of STAT proteins was confirmed by western blot, immunofluorescence and flow cytometry using phospho-specific anti-STAT antibodies, which recognize only phosphorylated STAT proteins. The incubation of MG-63 cells with IFN-γ caused the upregulation of MHC class I and class II proteins when MG-63 cells were grown on zirconia and titanium discs. In sum, the present study shows that the JAK-STAT pathway is activated in MG-63 cells when they are incubated on titanium or zirconia surfaces.

Zirconia versus Titanium Implants: 8-Year Follow-Up in a Patient Cohort Contrasted with Histological Evidence from a Preclinical Animal Model

Zirconia ceramic (ZC) implants are becoming more common, but comparisons between preclinical histology and long-term clinical trials are rare. This investigation comprised (1) 8-year clinical follow-up of one-piece ZC or titanium (Ti) implants supporting full overdentures and (2) histomorphometric analysis of the same implants in an animal model, comparing implants with various surface treatments. Methods: (1) Clinical trial: 24 completely edentulous participants (2 groups of N = 12) received 7 implants (one-piece ball-abutment ZC or Ti; maxilla N = 4, mandible N = 3) restored with implant overdentures. Outcomes after 8-years included survival, peri-implant bone levels, soft-tissue responses, and prosthodontic issues. (2) Preclinical trial: 10 New Zealand sheep received 4 implants bilaterally in the femoral condyle: Southern Implants ZC or Ti one-piece implants, identical to the clinical trial, and controls: Southern ITC^® two-piece implants with the same surface or Nobel (NBC) anodised (TiUnite™) surface. %Bone-implant contact (%BIC) was measured after 12 weeks of unloaded healing. Results: 8 of 24 participants (33%) of an average age of 75 ± 8 years were recalled; 21% of original participants had died, and 46% could not be contacted. 80.4% of implants survived; excluding palatal sites, 87.5% of Ti and 79% of ZC implants survived. All failed implants were in the maxilla. Three ZC implants had fractured. Bone loss was similar for Ti vs. ZC; pocket depths (p = 0.04) and attachment levels (p = 0.02) were greater for Ti than ZC implants. (1.7 ± 1.6 mm vs. 1.6 ± 1.3 mm). All implants in sheep femurs survived. %BIC was not statistically different for one-piece blasted surface Ti (80 ± 19%) versus ZC (76 ± 20%) or ITC^® (75 ± 16 mm); NBC had significantly higher %BIC than ITC (84 ± 17%, p = 0.4). Conclusion: Short-term preclinical results for ZC and Ti one-piece implants showed excellent bone-implant contact in unloaded femoral sites. This differed from the long-term clinical results in older-aged, edentulous participants. While ZC and Ti implants showed equivalent performance, the risks of peri-implantitis and implant loss in older, completely edentulous patients remain a significant factor.

Advancing dental implants: Bioactive and therapeutic modifications of zirconia

Zirconium-based implants have gained popularity in the dental implant field owing to their corrosion resistance and biocompatibility, attributed to the formation of a native zirconia (ZrO₂) film. However, enhanced bioactivity and local therapy from such implants are desirable to enable the earlier establishment and improved long-term maintenance of implant integration, especially in compromised patient conditions. As a result, surface modification of zirconium-based implants have been performed using various physical, chemical and biological techniques at the macro-, micro-, and nano-scales. In this extensive review, we discuss and detail the development of Zr implants covering the spectrum from past and present advancements to future perspectives, arriving at the next generation of highly bioactive and therapeutic nano-engineered Zr-based implants. The review provides in-depth knowledge of the bioactive/therapeutic value of surface modification of Zr implants in dental implant applications focusing on clinical translation.

Relevant Aspects of Titanium and Zirconia Dental Implants for Their Fatigue and Osseointegration Behaviors

Osseointegration capacity and good mechanical behavior are key to the success of the dental implant. In many investigations, comparisons of properties are made using different dental implant designs and therefore the results can be influenced by the macrodesign of the dental implant. In this work, studies were carried out with the same dental implant model using different roughness and different materials—commercially pure titanium (grade 4) and zirconia. For this purpose, 80 smooth passivated titanium (Ti), 80 smooth zirconia (ZrO₂), and 80 rough passivated titanium (Ti-R) dental implants were used. The samples were characterized by their roughness, wettability, surface energy, residual stresses, and fatigue behavior. The implants were implanted in minipigs for 4 and 12 weeks. The animals were sacrificed, and histological studies were carried out to determine the osseointegration parameters for each of the implantation times. Ti and ZrO₂ dental implants have very similar wettability and surface energy properties. However, the roughness causes a decrease in the hydrophilic character and a decrease of the total surface energy and especially the dispersive component, while the polar component is higher. Due to the compressive residual stresses of alumina sandblasting, the rough dental implant has the best fatigue behavior, followed by Ti and due to the lack of toughness and rapid crack propagation the ZrO₂ implants have the worst fatigue behavior. The bone index contact (BIC) values for 4 weeks were around 25% for Ti, 32% for ZrO₂, and 45% for Ti-R. After 12 weeks the Ti dental implants increased to 42%, for Ti, 43% for ZrO₂, and an important increase to 76% was observed for Ti-R implants. In vivo results showed that the key factor that improves osseointegration is roughness. There was no significant difference between ZrO₂ and Ti implants without sandblasting.

Surface Structure of Zirconia Implants: An Integrative Review Comparing Clinical Results with Preclinical and In Vitro Data

Background: The purpose of this review was to analyze and correlate the findings for zirconia implants in clinical, preclinical and in vitro cell studies in relation to surface structure. Methods: Electronic searches were conducted to identify clinical, preclinical and in vitro cell studies on zirconia implant surfaces. The primary outcomes were mean bone loss (MBL) for clinical studies, bone-to-implant contact (BIC) and removal torque (RT) for preclinical studies and cell spreading, cell proliferation and gene expression for cell studies. The secondary outcomes included comparisons of data found for those surfaces that were investigated in all three study types. Results: From 986 screened titles, 40 studies were included for data extraction. In clinical studies, only micro-structured surfaces were investigated. The lowest MBL was reported for sandblasted and subsequently etched surfaces, followed by a sinter and slurry treatment and sandblasted surfaces. For BIC, no clear preference of one surface structure was observable, while RT was slightly higher for micro-structured than smooth surfaces. All cell studies showed that cell spreading and cytoskeletal formation were enhanced on smooth compared with micro-structured surfaces. Conclusions: No correlation was observed for the effect of surface structure of zirconia implants within the results of clinical, preclinical and in vitro cell studies, underlining the need for standardized procedures for human, animal and in vitro studies.

Topographical changes and bactericidal efficacy of antimicrobial photodynamic therapy on titanium implant surface

BACKGROUND

A lot of research has been done on various disinfection modalities used to achieve an aseptic implant surface. However, the bacterial efficacy and the topographical alterations resulting from the use of these techniques have never been compared.

OBJECTIVE

This study aimed to evaluate and compare the disinfection efficacy and surface changes on a bacteria contaminated titanium block following application of various disinfectants.

METHOD

Ultrasonically cleaned titanium blocks were contaminated with Porphyromonas gingivalis and Tannerella forsythia. The infected titanium implants were randomly divided into four experimental groups and decontaminated using antimicrobial photodynamic therapy (aPDT), laser therapy, chlorhexidine and hydrogen peroxide. Bacterial viability and surface changes following decontamination were analyzed.

RESULT

Bacterial viability decreased in all the groups with aPDT having the highest reduction. Surface roughness remained unchanged whereas the contact angle lessened in the aPDT group.

CONCLUSION

aPDT could possibly be a suitable alternative to other disinfection regimen to treat periimplantitis.

A Three – Dimensional Finite Element Analysis of Polyetheretherketone PEEK in Dental Implant Prosthesis: A Novel Implant System

Purpose:

This current numerical investigation aim to evaluate the benefits of substituting Titanium with CRF- PEEK for better stress distribution in implant- bone interface.

Methods:

3D models of a dental implant for the first mandibular molar were constructed using the computed tomography (CT) scan. Four distinct models using a combination of titanium, carbon reinforced polyetheretherketone (CRF- PEEK), and zirconia for implant /abutment materials were studied. A three- dimensional finite element simulation was used to evaluate the stress distribution at the implant – bone interface under a compressive axial load of magnitude 120 N. A spherical indenter was used to simulate occlusal load.

Results:

Mesh independent study was converged for a very large number of elements. Finite element analysis showed: 1) there was no significant difference in the distribution pattern of stress at the implant – bone interface in the different material models studied, 2) the stress values for all prosthetic implant parts were well below the yield strength, 3) a larger deformation of PEEK implant versus titanium.

Conclusion:

The substitution of titanium with PEEK for the implant does not provide any better stress distribution and may lead to problems from the deformation of the implant.

Biocompatible Materials in Otorhinolaryngology and Their Antibacterial Properties

For decades, biomaterials have been commonly used in medicine for the replacement of human body tissue, precise drug-delivery systems, or as parts of medical devices that are essential for some treatment methods. Due to rapid progress in the field of new materials, updates on the state of knowledge about biomaterials are frequently needed. This article describes the clinical application of different types of biomaterials in the field of otorhinolaryngology, i.e., head and neck surgery, focusing on their antimicrobial properties. The variety of their applications includes cochlear implants, middle ear prostheses, voice prostheses, materials for osteosynthesis, and nasal packing after nasal/paranasal sinuses surgery. Ceramics, such as as hydroxyapatite, zirconia, or metals and metal alloys, still have applications in the head and neck region. Tissue engineering scaffolds and drug-eluting materials, such as polymers and polymer-based composites, are becoming more common. The restoration of life tissue and the ability to prevent microbial colonization should be taken into consideration when designing the materials to be used for implant production. The authors of this paper have reviewed publications available in PubMed from the last five years about the recent progress in this topic but also establish the state of knowledge of the most common application of biomaterials over the last few decades.

Main Applications and Recent Research Progresses of Additive Manufacturing in Dentistry

In recent ten years, with the fast development of digital and engineering manufacturing technology, additive manufacturing has already been more and more widely used in the field of dentistry, from the first personalized surgical guides to the latest personalized restoration crowns and root implants. In particular, the bioprinting of teeth and tissue is of great potential to realize organ regeneration and finally improve the life quality. In this review paper, we firstly presented the workflow of additive manufacturing technology. Then, we summarized the main applications and recent research progresses of additive manufacturing in dentistry. Lastly, we sketched out some challenges and future directions of additive manufacturing technology in dentistry.

Surface modification of zirconia dental implants by laser texturing

The aim of this work was to perform an integrative literature review on the influence of laser irradiation on zirconia implants to enhance surface topographic aspects and the biological response for osseointegration. An electronic search was carried out on the PubMed database using the following search terms: "zirconia" AND "laser" AND "surface modification" OR "surface treatment" AND "dental implants" OR "bone" OR "osteoblast" OR "osseointegration." Of the identified articles, 12 studies were selected in this review. Results reported that the laser irradiation was capable of promoting changes on the zirconia surfaces regarding topographic aspects, roughness, and wettability. An increase in roughness was recorded at micro- and nano-scale and it resulted in an enhanced wettability and biological response. Also, adhesion, spreading, proliferation, and differentiation of osteogenic cells were also enhanced after laser irradiation mainly by using a femtosecond laser at 10nJ and 80 MHz. After 3 months of osseointegration, in vivo studies in dogs revealed a similar average percentage of bone-to-implant contact (BIC) on zirconia surfaces (around 47.9 ± 16%) when compared to standard titanium surfaces (61.73 ±16.27%), denoting that there is no significant difference between such different materials. The laser  approach revealed several parameters that can be used for zirconia surface modification such as irradiation intensity, time, and frequency. Laser irradiation parameters can be optimized and well-controlled to reach desirable surface morphologic aspects and biological response concerning the osseointegration process.

Finite element analysis to assess stress and deformation in bone with glass fiber-reinforced-poly-ether-ether-ketone, zirconia, and titanium implants

Objectives

Recently, zirconia ceramic and glass or carbon fiber-reinforced poly-ether-ether-ketone (PEEK) composites have been introduced as newer implant biomaterials. This study was done to evaluate stress and deformation in bone with glass fiber-reinforced (GFR)-PEEK, zirconia, and titanium implants.

Materials and Methods

A geometric model of mandibular molar replaced with implant-supported crown was generated. Implant of 12 mm length and 4.5 mm diameter was used in study. Finite element analysis models of implant assemblies of three materials GFR-PEEK, zirconium, and titanium were generated. 150 N loads were applied obliquely and vertically along the long axis of implant. Von Mises stresses and deformation generated were compared using ANSYS Workbench 17.0 and finite element software.

Results

All three implant assemblies, i.e., GFR-PEEK, zirconia, and titanium, demonstrated similar stresses and deformation in bone without significant difference.

Conclusion

It was concluded that GFR-PEEK and zirconia implants can be used as a substitute to titanium implants.

Finite element evaluation to compare stress pattern in bone surrounding implant with carbon fiber-reinforced poly-ether-ether-ketone and commercially pure titanium implants

Background:

Titanium allergy is a main reason for failure of dental implant. Hence, newer implant biomaterials have emerged such as zirconia and carbon or glass fiber reinforced poly-ether-ether-ketone (CFR-PEEK)-based materials. The aim of the present study was to compare the stress pattern in bone surrounding implant with CFR-PEEK and commercially pure titanium implant.

Materials and Methods:

Three-dimensional formal model of mandibular first molar partsubstituting with implant supported crown was generated. Implant with dimensions of 10 mm length and 4.3 mm diameter was used in this study. Finite element models of CFR-PEEK and commercially pure titanium implant assemblies were generated. A 100 Newton (N) force was implemented along the long axis and obliquely at 30° to the long axis of implant. Von Mises pressures generated in the bone surrounding implant were analyzed using ANSYS workbench 16.0 and other finite element software.

Results:

Similar stress distribution was detected in bone surrounding implant with CFR-PEEK implant and commercially pure titanium implant assembly under 100 N force applied vertically and obliquely.

Conclusion:

PEEK reinforced with carbon or glass fiber implants can be a viable alternative in individuals who are more of esthetic concern and who demonstrate allergy to metallic implants.

A Clinical and Radiographic Evaluation of Zirconia Dental Implants: 10-Year Follow-Up

PURPOSE

The aim is to evaluate the survival and success rates, as well as the marginal bone loss (MBL) and periodontal indexes, of zirconia implants with 10-year follow-up.

MATERIALS AND METHODS

10 patients were selected and 26 one-piece zirconia implants were used for the rehabilitation of single tooth or partially edentulous ridge. After 10 years, a clinical-radiographic evaluation was performed in order to estimate peri-implant tissue health and marginal bone loss.

RESULTS

The survival and success rates were 100%. The average marginal bone loss from baseline to 120 months after surgery was 0.92 ± 0.97 mm.

CONCLUSION

One-piece zirconia dental implants are characterised by high biocompatibility, low plaque adhesion, and absence of microgap that can be related to the clinical success of these implants.

Is titanium-zirconium alloy a better alternative to pure titanium for oral implant? Composition, mechanical properties, and microstructure analysis

Introduction

Titanium (Ti) is widely accepted as a biomaterial for orthopaedic and dental implants, primarily due to its capacity to integrate directly into the bone and its superior corrosion resistance. It has been suggested that titanium–zirconium alloy (TiZr), with 13–17% of zirconium, has better mechanical properties than pure Ti, but there are very few published studies assessing the suitability of TiZr for high-load- bearing implants. This study aimed to compare the mechanical properties and microstructures of TiZr and commercially pure titanium (Ti).

Methodology

Pure Ti and TiZr alloy discs were prepared and subjected to characterisation by nanoindentation, electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD).

Results

The TiZr alloy was found to have significantly lower elastic modulus value (p < 0.0001) and greater hardness than Ti (p < 0.05). The EDS results confirmed the presence of Zr (13–17%) in the TiZr alloy, with XRD and EBSD images showing microstructure with the alpha phase similar to commercially available Ti.

Conclusion

The lower elastic modulus, higher hardness, presence of alpha phase, and the finer grain size of the TiZr alloy make it more suitable for high-load-bearing implants compared to commercially available Ti and is likely to encourage a positive biological response.

Biomimetic Composite Coatings for Activation of Titanium Implant Surfaces: Methodological Approach and In Vivo Enhanced Osseointegration

Innovative nanomaterials are required for the coatings of titanium (Ti) implants to ensure the activation of Ti surfaces for improved osseointegration, enhanced bone fracture healing and bone regeneration. This paper presents a systematic investigation of biomimetic composite (BC) coatings on Ti implant surfaces in a rat model of a diaphyseal femoral fracture. Methodological approaches of surface modification of the Ti implants via the usual joining methods (e.g., grit blasting and acid etching) and advanced physicochemical coating via a self-assembled dip-coating method were used. The biomimetic procedure used multi-substituted hydroxyapatite (ms-HAP) HAP-1.5 wt% Mg-0.2 wt% Zn-0.2 wt% Si nanoparticles (NPs), which were functionalized using collagen type 1 molecules (COL), resulting in ms-HAP/COL (core/shell) NPs that were embedded into a polylactic acid (PLA) matrix and finally covered with COL layers, obtaining the ms-HAP/COL@PLA/COL composite. To assess the osseointegration issue, first, the thickness, surface morphology and roughness of the BC coating on the Ti implants were determined using AFM and SEM. The BC-coated Ti implants and uncoated Ti implants were then used in Wistar albino rats with a diaphyseal femoral fracture, both in the absence and the presence of high-frequency pulsed electromagnetic shortwave (HF-PESW) stimulation. This study was performed using a bone marker serum concentration and histological and computer tomography (micro-CT) analysis at 2 and 8 weeks after surgical implantation. The implant osseointegration was evaluated through the bone–implant contact (BIC). The bone–implant interface was investigated using FE-SEM images and EDX spectra of the retrieved surgical implants at 8 weeks in the four animal groups. The obtained results showed significantly higher bone–implants contact and bone volume per tissue volume, as well as a greater amount of newly formed bone, in the BC-coated Ti implants than in the uncoated Ti implants. Direct bone–implant contact was also confirmed via histological examination. The results of this study confirmed that these biomimetic composite coatings on Ti implants were essential for a significant enhancement of osseointegration of BC-coated Ti implants and bone regeneration. This research provides a novel strategy for the treatment of bone fractures with possible orthopedic applications.

Classification and Properties of Dental Zirconia as Implant Fixtures and Superstructures

Various types of zirconia are widely used for the fabrication of dental implant superstructures and fixtures. Zirconia-alumina composites, such as ATZ and NanoZR, are adequate for implant fixtures because they have excellent mechanical strength in spite of insufficient esthetic properties. On the other hand, yttria-stabilized zirconia has been used for implant superstructures because of sufficient esthetic properties. They are classified to 12 types with yttria content, monochromatic/polychromatic, uniform/hybrid composition, and monolayer/multilayer. Zirconia with a higher yttria content has higher translucency and lower mechanical strength. Fracture strength of superstructures strongly depends on the strength on the occlusal contact region. It suggests that adequate zirconia should be selected as the superstructure crown, depending on whether strength or esthetics is prioritized. Low temperature degradation of zirconia decreases with yttria content, but even 3Y zirconia has a sufficient durability in oral condition. Although zirconia is the hardest dental materials, zirconia restorative rarely subjects the antagonist teeth to occlusal wear when it is mirror polished. Furthermore, zirconia has less bacterial adhesion and better soft tissue adhesion when it is mirror polished. This indicates that zirconia has advantageous for implant superstructures. As implant fixtures, zirconia is required for surface modification to obtain osseointegration to bone. Various surface treatments, such as roughening, surface activation, and coating, has been developed and improved. It is concluded that an adequately selected zirconia is a suitable material as implant superstructures and fixtures because of mechanically, esthetically, and biologically excellent properties.

Bacteria co-culture adhesion on different texturized zirconia surfaces

Zirconia is becoming reckoned as a promising solution for different applications, in particular those within the dental implant investigation field. It has been proved to successfully overcome important limitations of the commonly used titanium implants. The adhesion of microorganisms to the implants, in particular of bacteria, may govern the success or the failure of a dental implant, as the accumulation of bacteria on the peri-implant bone may rapidly evolve into periodontitis. However, bacterial adhesion on different zirconia architectures is still considerably unknown. Therefore, the adhesion of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa to zirconia surfaces with different finishings was evaluated and compared to a titanium surface. The adhesion interaction between S. aureus and P. aeruginosa was also evaluated using a co-culture since these bacteria are infamous due to their common presence in chronic wound infections. Results showed that different bacterium species possess different properties which influence their propensity to adhere to different roughness levels and architectures. E. coli revealed a higher propensity to adhere to zirconia channelled surfaces (7.15 × 10⁶ CFU/mL), whereas S. aureus and P. aeruginosa adhered more to the titanium control group (1.07 × 10⁵ CFU/mL and 8.43 × 10⁶ CFU/mL, respectively). Moreover, the co-culture denoted significant differences on the adhesion behaviour of bacteria. Despite not having shown an especially better behaviour regarding bacterial adhesion, zirconia surfaces with micro-channels are expected to improve the vascularization around the implants and ultimately enhance osseointegration, thus being a promising solution for dental implants.

Zirconia Materials for Dental Implants: A Literature Review

Titanium is currently the most commonly used material for manufacturing dental implants. However, its potential toxic effects and the gray color have resulted in increasing requests for metal-free treatment options. Zirconia is a type of ceramic materials that has been extensively used in medicine field, such as implant abutments and various joint replacement appliances. Amounts of clinical evaluations have indicated good biocompatibility for zirconia products. Besides, its toothlike color, low affinity for plaque and outstanding mechanical and chemical properties have made it an ideal candidate for dental implants. The aim of this study is to review the laboratory and clinical papers about several kinds of zirconia materials and zirconia surface modification techniques. Although there are plenty of literatures on these topics, most of the researches focused on the mechanical properties of the materials or based on cell and animal experiments. Randomized clinical trials on zirconia materials are still urgently needed to validate their application as dental implants.

Evaluating the osteogenic potential of insulin-like growth factor-1 microspheres on osteoblastic activity around dental implants in patients with type 2 diabetes mellitus using bone scintigraphy: A split-mouth randomized controlled trial

STATEMENT OF PROBLEM

Dental implants are susceptible to early failure when placed in patients diagnosed with type 2 diabetes mellitus. The osteoinductive potential of insulin-like growth factor-1 (IGF-1) has been widely investigated in animals with type 2 diabetes mellitus, but studies investigating the osteoinductive potential of IGF-1 around dental implants in patients diagnosed with type 2 diabetes mellitus are lacking.

PURPOSE

This randomized controlled trial was conducted to assess the osteogenic efficacy of poly(lactide-co-glycolide)- (PLGA) encapsulated IGF-1 microspheres around dental implants placed in patients diagnosed with type 2 diabetes mellitus.

MATERIAL AND METHODS

A split-mouth, randomized controlled trial was conducted in 10 participants diagnosed with type 2 diabetes mellitus and with bilaterally missing mandibular posterior teeth. The 20 sites were randomly allotted to receive the PLGA encapsulated IGF-1 or placebo microspheres followed by the placement of Ø3.8×11-mm implants. Osteoblastic activity was quantitatively assessed with bone scintigraphy scanning on the thirtieth, sixtieth, and 90th day after implant placement. The Shapiro-Wilks test was used to analyze the normality of data, followed by the independent t test to compare the experimental and placebo groups. Intragroup comparison was performed by using repeated-measures ANOVA and the post hoc Bonferroni test (α=.05).

RESULTS

Statistical analysis revealed that the mean osteoblastic activity was higher in the experimental group which received the PLGA-encapsulated IGF-1 than in the placebo group at the 30th, 60th, and 90th day after implant placement (P≤.001).

CONCLUSIONS

This randomized controlled trial indicated that the PLGA-encapsulated sustained release of IGF-1 microspheres enhanced the process of osseointegration in patients diagnosed with type 2 diabetes mellitus until the 90th day after implant placement.

Histologic and histomorphometric evaluation of new zirconia-based ceramic dental implants: A preclinical study in dogs

OBJECTIVE

Healing of soft tissues and improvement of aesthetics have become major research objectives in implantology and renewed the interest for ceramics implants. The aim of this study was to evaluate the pre-clinical performance of screw-shaped sandblasted-etched implants processed from an innovative zirconia-based ceramic composite, in comparison to titanium.

METHODS

Twenty-four ceramic and twenty-four titanium screw-shaped sandblasted-etched dental implants were tested in a split-mouth design in six Beagle dogs. Surface topographies were investigated by confocal microscopy. Local tissue effects were evaluated at 4 and 13 weeks after implantation through histology. An ANOVA statistical analysis (5% risk; p < 0.05) was performed to compare peri-implant quantitative histomorphometric parameters on buccal and lingual sides, including Bone to Implant Contact (BIC) among test groups and time-periods.

RESULTS

Titanium and ceramic implants presented respectively moderate and minimal roughness. After 4 and 13 weeks, ceramic implants showed an inflammatory tissue response close to titanium implants. At both period of time there was no significant difference between the titanium and ceramic groups in terms of BIC values (mean ± SD) at the lingual or buccal sides or when combining buccal + lingual BIC values (respectively for titanium and ceramic, 68.4 ± 14.7 % and 75.0 ± 13.5 % at 4 weeks, and 92.0 ± 8.6 % and 86.1 ± 13.8 % at 13 weeks).

SIGNIFICANCE

Within the limits of the present study, it can be concluded that newly developed zirconia-based ceramic composite dental implants have similar biocompatibility and osseointegration to those observed in titanium implants. These pre-clinical results corroborate the potential for the use of these new zirconia-based ceramics in oral implantology.

Stable sol-gel hydroxyapatite coating on zirconia dental implant for improved osseointegration

Aside from being known for its excellent mechanical properties and aesthetic effect, zirconia has recently attracted attention as a new dental implant material. Many studies have focused on hydroxyapatite (HA) coating for obtaining improved biocompatibility, however the coating stability was reduced by a byproduct produced during the high-temperature sintering process. In this study, to overcome this problem, we simply coated the zirconia surface with a sol-gel-derived hydroxyapatite (HA) layer and then sintered it at a varied temperature (<1000 °C). The surface showed a nanoporous structure, and there was no crystalline phase other than HA and zirconia when the sintering temperature was 800 °C. The adhesion strength of the HA layer (>40 MPa) was also appropriate as a dental implant application. In addition, in vitro cell experiments using a preosteoblast cell line revealed that the HA-coated zirconia surface acts as a preferable surface for cell attachment and proliferation than bare zirconia surface. In vivo animal experiments also demonstrated that the osteoconductivity of zirconia were dramatically enhanced by HA coating, which was comparable to that of Ti implant. These results suggest that the sol-gel-based HA-coated zirconia has a great potential for use as a dental implant material.

Comparative evaluation of surface-modified zirconia for the growth of bone cells and early osseointegration

STATEMENT OF PROBLEM

Rapid osseointegration between implant and bone tissue for early loading of a prosthesis with sufficient primary stability depends on the surface characteristics of the implant. The development and characterization of suitable surface coatings on dental implants is a major challenge.

PURPOSE

The purpose of this in vitro study was to evaluate and compare the osteogenic potential and cytotoxicity of unmodified zirconia, acid-etched zirconia, bioactive glass-coated zirconia, and tamarind kernel polysaccharide with hydrophilic acrylic acid (TKP-AA) hydrogel-coated zirconia.

MATERIAL AND METHODS

Thirty-six disks each of unmodified zirconia, acid-etched, 45S5 bioactive glass-coated, and TKP-AA hydrogel-coated zirconia were evaluated for osteogenic potential and cytotoxic effect by using human osteoblast Saos-2 cells. The surface topography of the disks and the morphology of the cells grown on these surfaces were examined by scanning electron microscopy (n=3). The cell attachment was evaluated by confocal imaging (n=3). The cytotoxic effect was evaluated by cell viability assay (n=9). Osteoblast maturation was assessed by alkaline phosphatase assay (n=9) and cell mineralization by alizarin red staining (n=9). ANOVA and Bonferroni multiple comparison post hoc tests were used to evaluate the statistical significance of the intergroup differences in these characteristics (α=.05).

RESULTS

The surface modifications resulted in distinct changes in the surface morphology of zirconia disks and the growth of Saos-2 cells. Zirconia disks coated with TKP-AA promoted higher proliferation of osteoblasts compared with unmodified disks (P<.001). Similarly, the surface modifications significantly increased the differentiation of mesenchymal stem cells to osteoblasts as compared with uncoated zirconia (P<.001). However, the rate of differentiation to osteoblasts was similar among the surface modifications. Acid-etched and TKP-AA-coated disks promoted mineralization of osteoblasts to the same extent, except bioactive glass coating, which significantly increased the rate of mineralization (P<.001).

CONCLUSIONS

Surface modification of zirconia by acid etching and coating with Bioglass or TKP-AA hydrogel resulted in the improved growth and differentiation of osteoblasts. TKP-AA hydrogel coating promoted the proliferation of osteoblasts, whereas Bioglass coating showed better mineralization. TKP-AA hydrogel coating is a promising candidate for improving the osseointegration of dental implants that warrants further investigation.

Customized Root-Analogue Implants: A Review on Outcomes from Clinical Trials and Case Reports

(1) It is estimated that 10% of the world’s population will need a dental implant in their lifetime. Despite all the advances in the comprehension of dental implant designs, materials and techniques, traditional implants still have many limitations. Customized root-analogue implants are, therefore, gaining increased interest in dental rehabilitation and are expected to not only preserve more hard and soft tissues but also avoid a second surgery and improve patient overall satisfaction. In this sense, the aim of this review was to collect and analyse the clinical trials and case reports on customized root-analogue implants available in the literature; (2) This review was carried out according to the PRISMA Statement. An electronic database search was performed using five databases: PubMed, Google Scholar, Medline, Science Direct, and Scopus. The following keywords were used for gathering data: custom-made, dental implants, root-analogue, anatomical, customized and tooth-like; (3) 15 articles meeting the inclusion criteria—articles reporting clinical trials, case reports or animal studies and articles with root-analogue implants and articles with totally customized implant geometries—were selected for the qualitative synthesis. The design and manufacturing techniques, implant material and surface treatments were assessed and discussed; (4) The performance of some root-analogue implants with specific features (i.e., macro-retentions) was successful, with no signs of infection, periodontitis nor bleeding during the follow-up periods.

Impact of Implant Surface Material and Microscale Roughness on the Initial Attachment and Proliferation of Primary Human Gingival Fibroblasts

Due to the rising demand for zirconia (Zr) based implant systems, it is important to understand the impact of Zr and titanium (Ti) implants and particularly their topography on soft tissue healing. As human gingival fibroblasts (hGFs) are the predominant cells in peri-implant soft tissue, we focused on examining the effect of implant material and surface roughness on hGFs' initial attachment, growth and the expression of proteins involved in the focal adhesion. hGFs isolated from eight healthy donors were cultured on the following surfaces: smooth titanium machined surface (TiM), smooth zirconia machined surface (ZrM), moderately rough titanium surface (SLA), or moderately rough zirconia surface (ZLA) for up to 14 days. The initial attachment of hGFs was evaluated by scanning electron microscopy. Cell proliferation/viability was assessed by cell counting kit 8. Focal adhesion and cytoskeleton were visualized by a focal adhesion staining kit. The gene expression of focal adhesion kinase (FAK), α-smooth muscle actin (α-SMA), and integrin subunits ITG-β1, ITG-β4, ITG-α4, ITG-α5, ITG-α6, was evaluated by qPCR. Cell proliferation/viability was slightly decreased by moderately rough surfaces, whereas no effect of surface material was observed. Cell morphology was strikingly different between differently treated surfaces: on machined surfaces, cells had elongated morphology and were attached along the grooves, whereas on moderately rough surfaces, cells were randomly attached. Surface roughness had a more pronounced effect on the gene expression compared to the surface material. The expression of FAK, α-SMA, ITG-β4, ITG-α5, and ITG-α6 was enhanced by moderately rough surfaces compared to smooth surfaces. Within the limitations of this in vitro study, it can be concluded that the behavior of primary hGFs is primarily affected by surface structure, whereas no apparent advantage of Zr over Ti could be observed.

Single tooth restoration in the maxillary esthetic zone using a one-piece ceramic implant with 1 year of follow-up: case series

Background

Oral implants have helped clinicians to improve the quality of life for many patients. The material of choice for dental implants currently remains titanium type IV, whose mechanical and biological properties have been proven throughout the history of implantology. Yet, this material is not exempt from complications. For these reasons, ceramic alternatives to titanium have emerged. Thus, the purpose of this study is to evaluate peri-implant hard and soft tissue stability with the use of a one-piece ceramic implant (Straumann® PURE Ceramic Implant) during 1 year of follow-up.

Study design

One-piece all-ceramic zirconia (ZrO₂) implants were placed to replace single missing teeth in the esthetic zone. Six to 8 weeks after the procedure, the definitive prosthesis was fabricated. At the time of prosthesis, placement (T₀) photographs and periapical radiographs were taken, and the following clinical parameters were recorded: probing depth (PD), plaque index (PI), bleeding on probing (BOP), suppuration on probing (SOP), distance from gingival margin to incisal edge (GM-IE), and Jemt papilla index (JPI). Follow-up appointments were scheduled at 4 (T₄), 8 (T₈), and 12 (T₁₂) months, when the same parameters were recorded. In addition, plaque control was reinforced and prophylaxis was carried out. In this last appointment, a final periapical radiograph was taken to assess marginal bone loss.

Results

A total of 32 zirconia implants were placed in 28 patients (16 women and 12 men, aged between 34 and 67 years). The survival and success rate were 93.75%. The increase in probing depth from baseline to 12 months was 0.78 mm. Assessments of plaque index and bleeding on probing showed a slight increase throughout the study.

Conclusions

The results obtained with the Straumann® PURE Ceramic implants show them to exhibit very good clinical behavior. The survival rate of the implants of our pilot study was 93.75%. For these reasons, we can say that zirconia implants could be an alternative to titanium implants in the esthetic zone.

Fatigue properties of hollow zirconia implants

The objective of this study was to clarify the fatigue behavior of hollow yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) specimens assuming its use for two-piece implants. The fatigue properties of a solid specimen (which simulated a one-piece implant) and 3 types of hollow specimens (which simulated two-piece implants) were evaluated. Specimens were either solid with a diameter of 4.0 mm (S) or hollow with an inner diameter of 3.0 mm and outer diameters of 4.0 mm (H0.5), 4.5 mm (H0.75), or 5.0 mm (H1.0). For each group, 25 specimens were prepared followed by blast and acid etch treatment. Static fracture and cyclic fatigue tests were conducted by modifying the methods provided in ISO6872. Fracture modes were determined by observing the surfaces under a scanning electron microscope. As a result, the cyclic fatigue load of S and H1.0 were similar, and hollow specimens with outer diameters greater than 0.75 mm displayed the ability to withstand molar occlusal forces.

A novel coating layer on zirconia using modified zinc phosphatizing method

Yttria doped ZrO₂ was deposited using an acidic zinc phosphatizing solution and the hydrothermal treatment. The coating was analyzed using a field emission-scanning electron microscope (FE-SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). A piston on three balls (ISO 6872) was used for the measurement of biaxial flexural strength. MC3T3-E1 cells attachment was evaluated by SEM, and cell proliferation were assessed using MTS assay™. SEM images confirmed that the zinc phosphate coating layer was successfully prepared and fully covered the surface. The measured adhesive strength of the coating was 79.11 MPa. In vitro cell study indicated that the coated sample had better cell morphology and proliferation. XRD and EDS analysis revealed that the crystalline coating structure indexed as zinc phosphate (hopeite) and the substrate was assigned as zirconia. The flexural strength test showed that the strength of zirconia before and after hydrothermal treatment was not affected.

Laser Surface Texturing for Biomedical Applications: A Review

For generating a texture or pattern on a work surface, one of the emerging processes is laser surface texturing (LST). It is an effective method for producing texture on a work surface. Literature shows that various lasers have been applied to generate textures on the surface of work materials. Recently, LST has shown tremendous potential in the field of biomedical applications. Applying the LST process, the efficacy of the biomaterial has been drastically improved. This paper presents an in-depth review of laser surface texturing for biomedical applications. The effect of LST on important biomaterial has been thoroughly studied; it was found that LST has extreme potential for surface modification of biomaterial and can be utilized for biomedical applications.

Using non-invasive neuroimaging to enhance the care, well-being and experimental outcomes of laboratory non-human primates (monkeys)

Over the past 10-20 years, neuroscience witnessed an explosion in the use of non-invasive imaging methods, particularly magnetic resonance imaging (MRI), to study brain structure and function. Simultaneously, with access to MRI in many research institutions, MRI has become an indispensable tool for researchers and veterinarians to guide improvements in surgical procedures and implants and thus, experimental as well as clinical outcomes, given that access to MRI also allows for improved diagnosis and monitoring for brain disease. As part of the PRIMEatE Data Exchange, we gathered expert scientists, veterinarians, and clinicians who treat humans, to provide an overview of the use of non-invasive imaging tools, primarily MRI, to enhance experimental and welfare outcomes for laboratory non-human primates engaged in neuroscientific experiments. We aimed to provide guidance for other researchers, scientists and veterinarians in the use of this powerful imaging technology as well as to foster a larger conversation and community of scientists and veterinarians with a shared goal of improving the well-being and experimental outcomes for laboratory animals.

Review on current limits and potentialities of technologies for biomedical ceramic scaffolds production

Osseointegration is defined by a stable and functional union between bone and a surface of a material. This phenomenon is influenced by the geometric and surface characteristics of the part where the bone cells will attach. A wide variety of studies proves that ceramic materials are strong competitors against conventional metals in the scope of bone tissue engineering. Ceramic scaffolds, porous structures that allow bone ingrowth, have been studied to enhance the osseointegration phenomenon. Geometric and dimensional parameters of the scaffold have influence in its performance as mechanical and structural supporter of bone growth. However, these parameters are conditioned by the manufacturing process by which these scaffolds are obtained. Several studies focusing on the production process of ceramic scaffolds have been developed, using 3D printing, stereolithography, selective laser sintering, green machining, robocasting, and others. The main purpose of this work is to evaluate and compare the different manufacturing processes by which ceramic scaffolds can be produced. This comparison addresses scaffold parameters like pore size, pore shape, porosity percentage, roughness, and so forth. Additionally, the different materials used in different manufacturing processes are also mentioned and discussed given its influence on a successful osseointegration while simultaneously displaying adequate mechanical properties. After making a screening on the available ceramic scaffolds manufacturing processes, several examples are presented, proving the potential of each of these manufacturing process for a given scaffold geometry.

Surface Characteristics and Bioactivity of Zirconia (Y-TZP) with Different Surface Treatments

Background:

Zirconia being a bio-inert material needs to be surface treated to render it more bioactive and enhance its osseointegration potential. However, bioactivity studies focusing on the ability of sandblasting and ultraviolet photofunctionalization (UVP) surface treatments in inducing apatite precipitation using simulated body fluid (SBF) are lacking.

Aim:

The aim of the study was to comparatively evaluate the effect of two different surface treatments—sandblasting with 50 µm alumina and UVP with ultraviolet C (UVC) light on the bioactivity of zirconia.

Materials and Methods:

A total of 33 discs with dimensions 10 mm × 2 mm were obtained from zirconia blanks (Amann Girrbach, Koblach, Austria) and randomly divided into three groups (n = 11), namely Group I (untreated), Group II (sandblasted), and Group III (UVP). Surface characteristics of representative test samples were analyzed using X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle goniometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX), to assess type of crystal phase of zirconia, surface roughness, wettability, surface topography, and elemental composition, respectively. SBF was prepared and calcium content in SBF (Ca-SBF) was determined using inductively coupled plasma mass spectrometry (ICP-MS).

Results:

Data were analyzed by one-way analysis of variance (ANOVA), post hoc Tukey honestly significant difference (HSD), and Student’s t test for statistical significance (P < 0.05, significant; P < 0.01, highly significant). Surface characteristics analyses revealed that XRD showed predominant tetragonal (t) zirconia crystal phase for all test groups. Mean surface roughness (Sa) of Group I was 41.83 nm, and it was significantly lesser than that of Group II (115.65 nm) and Group III (102.43 nm). Mean contact angles were 98.26°, 86.77°, and 68.03° for Groups I, II, and III, respectively, and these differences were highly significant. Mean pre-immersion Ca content in SBF was found to be 159 mg/L. Mean post-immersion Ca content was 70.10, 60.80, and 56.20 mg/L for Groups I, II, and III, respectively. Significant differences were found between Group I as compared to both Groups II and III. Bioactivity of Group III was marginally, but insignificantly higher with respect to Group II. Groups II and III were insignificant with respect to each other. Post-immersion XRD revealed predominant “t” phase, and SEM-EDX revealed well-formed, abundant calcium apatite layer on the treated samples as compared to that on untreated sample and an increasing Ca/P ratio from 1.15, 1.79 to 2.08, respectively from Group I to Group III.

Conclusion:

Within the limitations of this study, both sandblasting and UVP significantly and similarly improved bioactivity of zirconia as compared to the untreated samples, which was corroborated by the SEM-EDX results.

Reliability of an injection-moulded two-piece zirconia implant with PEKK abutment after long-term thermo-mechanical loading

Zirconia implants are appreciated in some clinical indications in light of their aesthetic appearance and good biocompatibility. The aim of this work was to evaluate the performance of a newly developed two-piece zirconia/polyether ketone ketone (PEKK) implant-abutment combination after long-term cyclic loading in a hydrothermal environment, using a new protocol adapted from two available ISO standards. Sixteen implants (n = 8/group) were embedded according to ISO 14801 and divided into two groups: implants in the Observational Group (OG) were cyclically loaded for 60 days (98 N, 10 million loading cycles, 2 Hz) in 85 °C water in a chewing simulator, while non-loaded/non-aged implants (as-received) constituted the Control Group (CG). After 4.7 million loading cycles, one OG implant fractured in the chewing simulator. The surviving implants were compared to CG implants by X-ray diffraction (XRD) to investigate potential ageing as suggested by ISO 13356, but also μ-Raman spectroscopy, Focused-Ion-Beam - Scanning-Electron-Microscopy (FIB-SEM), and load-to-fracture. Ageing was shown to have limited influence on the evaluated zirconia implant, with increased monoclinic content after loading/ageing being to a shallow transformed zone of ~2 μm at the implant surface. However, OG implants showed a significantly decreased fracture load of 751 ± 231 N (CG: 995 ± 161 N; p = .046). These values enable clinical application, but the fact that one failure was recorded during cyclic fatigue along with the significant decrease in strength after cyclic loading/ageing suggest that there may be room for further optimization of especially the PEKK abutment. Furthermore, good agreement was observed between the fracture modes of the implant that failed during the cyclic fatigue experiment and the in vivo failure of one implant during pre-clinical trials, validating the interest of the in vitro protocol used in this work to check the reliability of zirconia implant.

Customized Therapeutic Surface Coatings for Dental Implants

Dental implants are frequently used to support fixed or removable dental prostheses to replace missing teeth. The clinical success of titanium dental implants is owed to the exceptional biocompatibility and osseointegration with the bone. Therefore, the enhanced therapeutic effectiveness of dental implants had always been preferred. Several concepts for implant coating and local drug delivery had been developed during the last decades. A drug is generally released by diffusion-controlled, solvent-controlled, and chemical controlled methods. Although a range of surface modifications and coatings (antimicrobial, bioactive, therapeutic drugs) have been explored for dental implants, it is still a long way from designing sophisticated therapeutic implant surfaces to achieve the specific needs of dental patients. The present article reviews various interdisciplinary aspects of surface coatings on dental implants from the perspectives of biomaterials, coatings, drug release, and related therapeutic effects. Additionally, the various types of implant coatings, localized drug release from coatings, and how released agents influence the bone–implant surface interface characteristics are discussed. This paper also highlights several strategies for local drug delivery and their limitations in dental implant coatings as some of these concepts are yet to be applied in clinical settings due to the specific requirements of individual patients.