Histologic and Histomorphometric Behavior of Microgrooved Zirconia Dental Implants with Immediate Loading

LASER as a tool for surface modification of dental biomaterials: A review

In recent years, the application of lasers for modifying the surface topography of dental biomaterials has received increased attention. This review paper aims to provide an overview of the current status on the utilization of lasers as a potential tool for surface modification of dental biomaterials such as implants, ceramics, and other materials used for restorative purposes. A literature search was done for articles related to the use of lasers for surface modification of dental biomaterials in English language published between October 2000 and March 2023 in Scopus, Pubmed and web of science, and relevant articles were reviewed. Lasers have been mainly used for surface modification of implant materials (71%), especially titanium and its alloys, to promote osseointegration. In recent years, laser texturing has also emerged as a promising technique to reduce bacterial adhesion on titanium implant surfaces. Currently, lasers are being widely used for surface modifications to improve osseointegration and reduce peri-implant inflammation of ceramic implants and to enhance the retention of ceramic restorations to the tooth. The studies considered in this review seem to suggest laser texturing to be more proficient than the conventional methods of surface modification. Lasers can alter the surface characteristics of dental biomaterials by creating innovative surface patterns without significantly affecting their bulk properties. With advances in laser technology and availability of newer wavelengths and modes, laser as a tool for surface modification of dental biomaterials is a promising field, with excellent potential for future research.

Advanced materials and technologies for oral diseases

Oral disease, as a class of diseases with very high morbidity, brings great physical and mental damage to people worldwide. The increasing burden and strain on individuals and society make oral diseases an urgent global health problem. Since the treatment of almost all oral diseases relies on materials, the rapid development of advanced materials and technologies has also promoted innovations in the treatment methods and strategies of oral diseases. In this review, we systematically summarized the application strategies in advanced materials and technologies for oral diseases according to the etiology of the diseases and the comparison of new and old materials. Finally, the challenges and directions of future development for advanced materials and technologies in the treatment of oral diseases were refined. This review will guide the fundamental research and clinical translation of oral diseases for practitioners of oral medicine.

Mechanobiologically optimized Ti-35Nb-2Ta-3Zr improves load transduction and enhances bone remodeling in tilted dental implant therapy

The tilted implant with immediate function is increasingly used in clinical dental therapy for edentulous and partially edentulous patients with excessive bone resorption and the anatomic limitations in the alveolar ridge. However, peri-implant cervical bone loss can be caused by the stress shielding effect. Herein, inspired by the concept of “materiobiology”, the mechanical characteristics of materials were considered along with bone biology for tilted implant design. In this study, a novel Ti–35Nb–2Ta–3Zr alloy (TNTZ) implant with low elastic modulus, high strength and favorable biocompatibility was developed. Then the human alveolar bone environment was mimicked in goat and finite element (FE) models to investigate the mechanical property and the related peri-implant bone remodeling of TNTZ compared to commonly used Ti–6Al–4V (TC4) in tilted implantation under loading condition. Next, a layer-by-layer quantitative correlation of the FE and X-ray Microscopy (XRM) analysis suggested that the TNTZ implant present better mechanobiological characteristics including improved load transduction and increased bone area in the tilted implantation model compared to TC4 implant, especially in the upper 1/3 region of peri-implant bone that is “lower stress”. Finally, combining the static and dynamic parameters of bone, it was further verified that TNTZ enhanced bone remodeling in “lower stress” upper 1/3 region. This study demonstrates that TNTZ is a mechanobiological optimized tilted implant material that enhances load transduction and bone remodeling.

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The mechanical properties and deformation mechanisms of Ti–35Nb–2Ta–3Zr alloys were studied.

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The cell biocompatibility, a layer-by-layer correlation of the finite element and X-ray Microscopy analysis were evaluated.

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Ti–35Nb–2Ta–3Zr implant improves load transduction and enhances bone remodeling in tilted implantation models.

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Mechanobiologically optimized Ti–35Nb–2Ta–3Zr alloy meets the clinical application requirements of tilted implant therapy.

Biomimetic Implant Surfaces and Their Role in Biological Integration—A Concise Review

Background: The increased use of dental implants in oral rehabilitation has been followed by the development of new biomaterials as well as improvements in the performance of biomaterials already in use. This triggers the need for appropriate analytical approaches to assess the biological and, ultimately, clinical benefits of these approaches. Aims: To address the role of physical, chemical, mechanical, and biological characteristics in order to determine the critical parameters to improve biological responses and the long-term effectiveness of dental implant surfaces. Data sources and methods: Web of Science, MEDLINE and Lilacs databases were searched for the last 30 years in English, Spanish and Portuguese idioms. Results: Chemical composition, wettability, roughness, and topography of dental implant surfaces have all been linked to biological regulation in cell interactions, osseointegration, bone tissue and peri-implant mucosa preservation. Conclusion: Techniques involving subtractive and additive methods, especially those involving laser treatment or embedding of bioactive nanoparticles, have demonstrated promising results. However, the literature is heterogeneous regarding study design and methodology, which limits comparisons between studies and the definition of the critical determinants of optimal cell response.

Modification of Zirconia Implant Surfaces by Nd:YAG Laser Grooves: Does It Change Cell Behavior?

The aim of this study was to evaluate gingival fibroblasts and human osteoblasts’ response to textured Nd:YAG laser microgrooves, with different dimensions, on zirconia implant surfaces. A total of 60 zirconia disks (8 mm in diameter and 2 mm in thickness) were produced and divided between four study groups (N = 15): three laser-textured (widths between 125.07 ± 5.29 μm and 45.36 ± 2.37 μm and depth values from 50.54 ± 2.48 μm to 23.01 ± 3.79 μm) and a control group without laser treatment. Human osteoblasts and gingival fibroblasts were cultured on these surfaces for 14 days. FEG-SEM (Field Emission Gun–Scanning Electron Microscope) images showed cellular adhesion at 24 h, with comparable morphology in all samples for both cell types. A similar cell spreading within the grooves and in the space between them was observed. Cell viability increased over time in all study groups; however, no differences were found between them. Additionally, proliferation, ALP (Alkaline phosphatase) activity, collagen type I, osteopontin and interleukin levels were not significantly different between any of the study groups for any of the cell types. Analysis of variance to compare parameters effect did not reveal statistically significant differences when comparing all groups in the different tests performed. The results obtained revealed similar cell behavior based on cell viability and differentiation on different microtopographic laser grooves, compared to a microtopography only established by sandblasting and acid-etching protocol, the reference surface treatment on zirconia dental implants.

Laser Nd:YAG patterning enhance human osteoblast behavior on zirconia implants

Zirconia has been regarded as a promising material for dental implants, and Nd:YAG laser treatment has been proposed as a potential strategy to improve its bioactivity. The main aim of the present study was to evaluate the in vitro behavior of human fetal osteoblasts in contact with laser-textured zirconia implant surfaces assessing the effect of different texture patterns, spacing between laser passes and number of laser passes. Zirconia discs were produced and treated with Nd:YAG laser according to test group variables: texture (microgrooves and micropillar array), distance between surface features (25 μm, 30 μm and 35 μm), and laser passes [1, 2, 4, and 8]. Untextured sandblasted and acid-etched zirconia discs (SBAE) were used as controls. Human osteoblasts (hFOB 1.19) were cultured for 14 days on test and control samples. Morphology and cellular adhesion were observed using scanning electron microscopy (SEM). Cell viability and proliferation were evaluated at 1, 3, 7, and 14 days using a commercial resazurin-based method. Collagen type I was evaluated at 3 days using ELISA. Alkaline phosphatase (ALP) activity was evaluated at 7 days using a colorimetric enzymatic technique. Group comparisons were tested using ANOVA or Mann-Whitney test (Tukey's post hoc) using statistical software, and significance was set at p < 0.05. Cell viability and proliferation increased over time for all groups with statistically higher values for laser-textured groups when compared with control at 7 and 14 days in culture (p < 0.05). Collagen type I levels were higher for study groups (p < 0.05) when compared with control group. No statistically differences were detected for ALP activity levels between texture and control groups (p > 0.05). The results suggest that laser-machined zirconia implant surfaces may benefit biological osteoblast response. However, the type of texture, spacing at the range of 25-35 μm, and number of laser passes did not seem to be relevant variables.

Dual Nanofibrous Bioactive Coatings on TiZr Implants

The objective of this research was to obtain a dual coating with antimicrobial properties on TiZr implants. The metallic surfaces were modified with two biopolymers (poly(lactic acid) and polycaprolactone), the first deposited by dip coating and the second by electrospinning, in order to create a nanofibers type of coating with antibacterial and bioactive effect. The surface characteristics of the obtained bioactive coatings were evaluated by Fourier Transformed Infrared Spectroscopy, by scanning electron microscopy and by contact angle measurements. The electrochemical characterization of the coatings was performed in simulated body fluid. The metallic ion release from the coated implant materials was measured by inductively coupled plasma mass spectrometry. The in vitro antimicrobial properties of the coatings were studied using agar disc diffusion method and percentage inhibition of growth method for two bacterial strains—S. aureus and E. coli. The presence of silver nanoparticles presented high inhibition zone against gram negative bacteria like E. coli. Cell viability of MC3T3-E1 osteoblasts and cytoskeleton morphology, were tested in vitro for the biological evaluation. The results on in vitro cell response indicated good cell membrane integrity and viability for such nanofibrous bioactive coatings compared to the control substrate. These surface architectures design on implant materials holds promise for biomedical applications, presenting good antimicrobial properties and promote cell adhesion and proliferation.

Zirconia surface modifications for implant dentistry

BACKGROUND

Zirconia has emerged as a versatile dental material due to its excellent aesthetic outcomes such as color and opacity, unique mechanical properties that can mimic the appearance of natural teeth and decrease peri-implant inflammatory reactions.

OBJECTIVE

The aim of this review was to critically explore the state of art of zirconia surface treatment to enhance the biological and osseointegration behavior of zirconia in implant dentistry.

MATERIALS AND METHODS

An electronic search in PubMed database was carried out until May 2018 using the following combination of key words and MeSH terms without time periods: "zirconia surface treatment" or "zirconia surface modification" or "zirconia coating" and "osseointegration" or "biological properties" or "bioactivity" or "functionally graded properties".

RESULTS

Previous studies have reported the influence of zirconia-based implant surface on the adhesion, proliferation, and differentiation of osteoblast and fibroblasts at the implant to bone interface during the osseointegration process. A large number of physicochemical methods have been used to change the implant surfaces and therefore to improve the early and late bone-to-implant integration, namely: acid etching, gritblasting, laser treatment, UV light, CVD, and PVD. The development of coatings composed of silica, magnesium, graphene, dopamine, and bioactive molecules has been assessed although the development of a functionally graded material for implants has shown encouraging mechanical and biological behavior.

CONCLUSION

Modified zirconia surfaces clearly demonstrate faster osseointegration than that on untreated surfaces. However, there is no consensus regarding the surface treatment and consequent morphological aspects of the surfaces to enhance osseointegration.

Current status of zirconia implants in dentistry: preclinical tests

PURPOSE

This systematic review aimed to provide an overview of zirconia implants as well as regarding the outcome of the implant-restorative complex in preclinical studies.

STUDY SELECTION

An electronic search of the literature prior to July 2017 was performed to identify all articles related to preclinical research on zirconia implants. The search was conducted using MEDLINE (National Library of Medicine) and PubMed without restrictions concerning the date of publication. The search terminology included: zirconia implant, osseointegration, bone-to-implant contact, soft tissue, histology, histomorphometry, surface modification, surface roughness, surface characteristics, and restoration (connecting multiple keywords with AND, OR).

RESULTS

Fifty-seven studies were finally selected from an initial yield of 654 titles, and the data were extracted. The identified preclinical studies focused on several aspects related to zirconia implants, namely biocompatibility, mechanical properties, implant design, osseointegration capacity, soft tissue response, and restorative options. Due to heterogeneity of the studies, a meta-analysis was not possible. The most frequently used zirconia material for the fabrication of implants is yttria-stabilized tetragonal zirconia polycrystal. The resistance-to-fracture for zirconia implants ranged between 516-2044N. The mostly investigated parameter was osseointegration, which is compared to that of titanium. A lack of evidence was found with other parameters.

CONCLUSIONS

Due to its good biocompatibility as well as favorable physical and mechanical properties, zirconia implants are a potential alternative to titanium implants. However, knowledge regarding the implant-restorative complex and related aspects is still immature to recommend its application for daily practice.

Hard and soft tissue responses to implant made of three different materials with microgrooved collar in a dog model

The objective of the present study was to assess hard and soft tissue around dental implants made of three different materials with microgrooves on the collar surface. Microgrooved implants were inserted in the mandibles of five male beagles. Implants were made of three kinds of material; titanium (Ti), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and ceria partially stabilized zirconia/alumina nanocomposite (Ce-TZP/Al₂O₃). The animals were euthanatized at three months after implantation, and harvested tissue was analyzed by means of histology. All kinds of implant were osseointegrated, and there were no significant differences in any histomorphometric parameters among the three groups of microgrooved implants made of different materials. Within the limitations of this study, implants with microgrooves integrated into the surrounding bone tissue, without statistically significant differences among the three tested materials, Ti, Y-TZP, and Ce-TZP/Al₂O₃.

Incidental finding of a degrading zirconia dental implant 29 months after implantation: Histological and histomorphometrical analysis

With the emerging development and improvement of biomaterials, the application of ceramics in restorative medicine has experienced a renaissance. New production processes have reportedly helped to overcome unfavorable biomechanical characteristics of these materials, which lead to a wide application of zirconia as ground material for dental implants. Zirconia-based implants are biocompatible, demonstrate ability to osseointegrate and have a teeth-like color, rendering them to be an ideal replacement for titanium-based implant systems, which represent the current gold standard in implantology. However, there is a lack of standardized guidelines on production of zirconia-based implants and long-term studies on the stability of this material in vivo are missing. In this study we demonstrate for the first time the accumulation of degradation products of a commercially available one-piece zirconia-based dental implant 29 months after implantation, which was recovered following a traumatic accident. Biopsy specimens from the implant and the surrounding tissue attached to it were processed for histological and histomorphometrical analysis. Although the implant was well integrated into the anchoring bone, degradation particles were observed in tissues adjacent to lower aspects of the implant. The observed implant degradation might seriously compromise implant stability several years after implantation. This incidental finding highlights the requirement of further research on zirconia-based ceramics before they can be advertised as safe alternative to titanium-based implant systems. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2919-2923, 2018.

Osseointegration of zirconia dental implants in animal investigations: A systematic review and meta-analysis

OBJECTIVE

To determine the osseointegration rate of zirconium dioxide (ZrO₂) dental implants in preclinical investigations.

DATA

Data on the osseointegration rate was extracted considering the bone to implant contact (BIC), removal torque analysis (RTQ) and push-in tests. Meta analyses were conducted using multilevel multivariable mixed-effects linear regression models. The Šidák method was used in case of multiple testing.

SOURCES

An electronic screening of the literature (MEDLINE/Pubmed, Cochrane Library and Embase) and a supplementary manual search were performed. Animal investigations with a minimum sample size of 3 units evaluating implants made of zirconia (ZrO₂) or its composites (ZrO₂>50vol.%) were included.

STUDY SELECTION

The search provided 4577 articles, and finally 54 investigations were included and analyzed. Fifty-two studies included implants made from zirconia, 4 zirconia composite implants and 37 titanium implants. In total, 3435 implants were installed in 954 animals.

CONCLUSIONS

No significant influence of the evaluated bulk materials on the outcomes of interest could be detected. When comparing different animal models, significant differences for the evaluated variables could be found. These results might be of interest for the design of further animal investigations.

Comparison of peri-implant bone formation around injection-molded and machined surface zirconia implants in rabbit tibiae

The aim of this study was to compare osseointegration and surface characteristics of zirconia implants made by the powder injection molding (PIM) technique against those made by the conventional milling procedure in rabbit tibiae. Surface characteristics of 2 types of implants were evaluated. Sixteen rabbits received 2 types of external hex implants with similar geometry, either machined zirconia implants or PIM zirconia implants, in the tibiae. Removal torque tests and histomorphometric analyses were performed. The roughness of the PIM zirconia implants was higher than that of machined zirconia implants. The PIM zirconia implants exhibited significantly higher bone-implant contact and removal torque values than the machined zirconia implants (p<0.001). The osseointegration of the PIM zirconia implant is promising, and PIM, using the roughened mold etching technique, can produce substantially rougher surfaces on zirconia implants.