Evaluation of the osseointegration of dental implants coated with calcium carbonate: an animal study

Research Methodology and Mechanisms of Action of Current Orthopaedic Implant Coatings

Orthopedic implants are crucial interventions that are gaining greater importance in modern medicine to restore function to commonly affected joints. Each implantation carries the risk of implant-associated infection and loosening of the implant due to improper integration with soft tissue. Coating strategies have been developed to aid the growth of bone into the implant (osteointegration) and prevent biofilm formation to avoid infection. In this review, primary articles highlighting recent developments and advancements in orthopedic implant coating will be presented. Additionally, the methodology of the articles will be critiqued based on this research criteria: establishment of function on a theoretical basis, validation of coating function, and potential next steps/improvements based on results. A theoretical basis based on understanding the mechanisms at play of these various coatings allows for systems to be developed to tackle the tasks of osteointegration, subversion of infection, and avoidance of cytotoxicity. The current state of research methodology in coating design focuses too heavily on either osteointegration or the prevention of infection, thus, future development in medical implant coating needs to investigate the creation of a coating that accomplishes both tasks. Additionally, next steps and improvements to systems need to be better highlighted to move forward when problems arise within a system. Research currently showcasing new coatings is performed primarily in vitro and in vivo. More clinical trials need to be performed to highlight long-term sustainability, the structural integrity, and the safety of the implant.

Strontium Carbonate and Strontium-Substituted Calcium Carbonate Nanoparticles Form Protective Deposits on Dentin Surface and Enhance Human Dental Pulp Stem Cells Mineralization

Strontium acetate is applied for dental hypersensitivity treatment; however, the use of strontium carbonates for this purpose has not been described. The use of Sr-carbonate nanoparticles takes advantage of both the benefits of strontium on dentin mineralization and the abrasive properties of carbonates. Here in, we aimed to synthesize strontium carbonate and strontium-substituted calcium carbonate nanoparticles and test them as potential compounds in active dentifrices for treating dental hypersensitivity. For this, SrCO₃, Sr_0.5Ca_0.5CO₃, and CaCO₃ nanoparticles were precipitated using Na₂CO₃, SrCl₂, and/or CaCl₂ as precursors. Their morphology and crystallinity were evaluated by electron microscopy (SEM) and X-ray diffraction, respectively. The nanoparticles were added to a poly (vinyl alcohol) gel and used to brush dentin surfaces isolated from human third molars. Dentin chemical composition before and after brushing was investigated by infrared spectroscopy (FTIR) and X-ray dispersive energy spectroscopy. Dentin tubule morphology, obliteration, and resistance of the coatings to acid attack were investigated by SEM and EDS. The cytotoxicity and ability of the particles to trigger the mineralization of hDPSCs in vitro were studied. Dentin brushed with the nanoparticles was coated by a mineral layer that was also able to penetrate the tubules, while CaCO₃ remained as individual particles on the surface. FTIR bands related to carbonate groups were intensified after brushing with either SrCO₃ or Sr_0.5Ca_0.5CO₃. The shift of the phosphate-related FTIR band to a lower wavenumber indicated that strontium replaced calcium on the dentin structure after treatment. The coating promoted by SrCO₃ or Sr_0.5Ca_0.5CO₃ resisted the acid attack, while calcium and phosphorus were removed from the top of the dentin surface. The nanoparticles were not toxic to hDPSCs and elicited mineralization of the cells, as revealed by increased mineral nodule formation and enhanced expression of COL1, ALP, and RUNX2. Adding Sr_0.5Ca_0.5CO₃ as an active ingredient in dentifrices formulations may be commercially advantageous since this compound combines the well-known abrasive properties of calcium carbonate with the mineralization ability of strontium, while the final cost remains between the cost of CaCO₃ and SrCO₃. The novel Sr_0.5Ca_0.5CO₃ nanoparticles might emerge as an alternative for the treatment of dental hypersensitivity.

Surface Engineering Strategies to Enhance the In Situ Performance of Medical Devices Including Atomic Scale Engineering

Decades of intense scientific research investigations clearly suggest that only a subset of a large number of metals, ceramics, polymers, composites, and nanomaterials are suitable as biomaterials for a growing number of biomedical devices and biomedical uses. However, biomaterials are prone to microbial infection due to Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), hepatitis, tuberculosis, human immunodeficiency virus (HIV), and many more. Hence, a range of surface engineering strategies are devised in order to achieve desired biocompatibility and antimicrobial performance in situ. Surface engineering strategies are a group of techniques that alter or modify the surface properties of the material in order to obtain a product with desired functionalities. There are two categories of surface engineering methods: conventional surface engineering methods (such as coating, bioactive coating, plasma spray coating, hydrothermal, lithography, shot peening, and electrophoretic deposition) and emerging surface engineering methods (laser treatment, robot laser treatment, electrospinning, electrospray, additive manufacturing, and radio frequency magnetron sputtering technique). Atomic-scale engineering, such as chemical vapor deposition, atomic layer etching, plasma immersion ion deposition, and atomic layer deposition, is a subsection of emerging technology that has demonstrated improved control and flexibility at finer length scales than compared to the conventional methods. With the advancements in technologies and the demand for even better control of biomaterial surfaces, research efforts in recent years are aimed at the atomic scale and molecular scale while incorporating functional agents in order to elicit optimal in situ performance. The functional agents include synthetic materials (monolithic ZnO, quaternary ammonium salts, silver nano-clusters, titanium dioxide, and graphene) and natural materials (chitosan, totarol, botanical extracts, and nisin). This review highlights the various strategies of surface engineering of biomaterial including their functional mechanism, applications, and shortcomings. Additionally, this review article emphasizes atomic scale engineering of biomaterials for fabricating antimicrobial biomaterials and explores their challenges.

Pre-Clinical Models in Implant Dentistry: Past, Present, Future

Biomedical research seeks to generate experimental results for translation to clinical settings. In order to improve the transition from bench to bedside, researchers must draw justifiable conclusions based on data from an appropriate model. Animal testing, as a prerequisite to human clinical exposure, is performed in a range of species, from laboratory mice to larger animals (such as dogs or non-human primates). Minipigs appear to be the animal of choice for studying bone surgery around intraoral dental implants. Dog models, well-known in the field of dental implant research, tend now to be used for studies conducted under compromised oral conditions (biofilm). Regarding small animal models, research studies mostly use rodents, with interest in rabbit models declining. Mouse models remain a reference for genetic studies. On the other hand, over the last decade, scientific advances and government guidelines have led to the replacement, reduction, and refinement of the use of all animal models in dental implant research. In new development strategies, some in vivo experiments are being progressively replaced by in vitro or biomaterial approaches. In this review, we summarize the key information on the animal models currently available for dental implant research and highlight (i) the pros and cons of each type, (ii) new levels of decisional procedures regarding study objectives, and (iii) the outlook for animal research, discussing possible non-animal options.

The Calcium Phosphate Modified Titanium Implant Combined With Platelet-Rich Plasma Treatment Promotes Implant Stabilization in an Osteoporotic Model

ABSTRACT

Osteoporosis as a kind of systemic bone metabolic disease has become one of the most prevalent diseases among the middle- and old-age, characterized with low bone mass and disruptive osseous microenvironment. The poor bone condition both in quantity and quality makes it daunting for osteoporotic patients who are submitted to dental implantation, joint replacement therapy, or orthopedic surgery. Since calcium phosphate (CaP) and platelet-rich plasma (PRP) treatment, all have improving the effect on bone regeneration. Inspired by this fact, the authors introduced a kind of novel implant with CaP modified surface by HPT (hydrothermal & pressure) treatment in this study. After producing, the authors tested its physicochemical properties through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS) and contact-angle measurement. Then the authors desired to investigate the effect of this CaP-modified implant on bone regeneration and stabilization maintenance combined with PRP treatment by establishing an osteoporotic rat model. After 3 months of surgery, the authors collected all the specimens and evaluated new bone formation by micro-computed tomography (micro-CT) analysis, biomechanical test, and histologic assessment. All the results in vivo experiment showed the CaP modified implant combined with PRP treatment could improve the osteoinductive effect under osteoporotic condition, leading to better maintenance for stabilization between bone and implant interface, which might be rendered as a promising clinical method for osteoporotic patients when they receive orthopedic surgeries.

Peri-Implant bone response around porous-surface dental implants: A preclinical meta-analysis

Introduction

This meta-analysis of relevant animal studies was conducted to assess whether the use of porous-surface implants improves osseointegration compared to the use of non-porous-surface implants.

Material and methods

An electronic search of PubMed (MEDLINE) resulted in the selection of ten animal studies (out of 865 publications) for characterization and quality assessment. Risk of bias assessment indicated poor reporting for the majority of studies. The results for bone-implant contact (BIC%) and peri-implant bone formation (BF%) were extracted from the eligible studies and used for the meta-analysis. Data for porous-surface implants were compared to those for non-porous-surface implants, which were considered as the controls.

Results

The random-effects meta-analysis showed that the use of porous-surface implants did not significantly increase overall BIC% (mean difference or MD: 3.63%; 95% confidence interval or 95% CI: −1.66 to 8.91; p = 0.18), whereas it significantly increased overall BF% (MD: 5.43%; CI: 2.20 to 8.67; p = 0.001), as compared to the controls.

Conclusion

Porous-surface implants promote osseointegration with increase in BF%. However, their use shows no significant effect on BIC%. Further preclinical and clinical investigations are required to find conclusive evidence on the effect of porous-surface implants.

Non-Invasive Luciferase Imaging of Type I Interferon Induction in a Transgenic Mouse Model of Biomaterial Associated Bacterial Infections: Microbial Specificity and Inter-Bacterial Species Interactions

The performance of biomaterials is often compromised by bacterial infections and subsequent inflammation. So far, the conventional analysis of inflammatory processes in vivo involves time-consuming histology and biochemical assays. The present study employed a mouse model where interferon beta (IFN-β) is monitored as a marker for non-invasive rapid detection of inflammation in implant-related infections. The mouse model comprises subcutaneous implantation of morphologically modified titanium, followed by experimental infections with four taxonomically diverse oral bacteria: Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Treponema denticola (as mono culture or selected mixed-culture). IFN-β expression increased upon infections depending on the type of pathogen and was prolonged by the presence of the implant. IFN-β expression kinetics reduced with two mixed species infections when compared with the single species. Histological and confocal microscopy confirmed pathogen-specific infiltration of inflammatory cells at the implant-tissue interface. This was observed mainly in the vicinity of infected implants and was, in contrast to interferon expression, higher in infections with dual species. In summary, this non-invasive mouse model can be used to quantify longitudinally host inflammation in real time and suggests that the polymicrobial character of infection, highly relevant to clinical situations, has complex effects on host immunity.

Otoliths-composed gelatin/sodium alginate scaffolds for bone regeneration

Evidence that otoliths, mineral-rich limestone concrescences present in the inner ear of bone fishes, can accelerate bone formation in vivo has been previously reported. The goal of this work was the development, characterization, and evaluation of the cytocompatibility of otoliths-incorporated sodium alginate and gelatin scaffolds. Cynoscion acoupa-derived otoliths were characterized by X-ray fluorescence spectrometry (FRX), particle size, free lime, and weight loss by calcination. Furthermore, otoliths were incorporated into sodium alginate (ALG/OTL-s) or gelatin (GEL/OTL-s) scaffolds, previously developed by freeze-drying. Then, the scaffolds were characterized by thermogravimetric analysis (TGA/DTG), differential scanning calorimetry (DSC), infrared spectroscopy with Fourier transform (FTIR), swelling tests, and scanning electron microscopy (SEM). Cytotoxicity assays were run against J774.G8 macrophages and MC3T3-E1 osteoblasts. Data obtained from TGA/DTG, DSC, and FTIR analyses confirmed the interaction between otoliths and the polymeric scaffolds. SEM showed the homogeneous porous 3D structure rich in otolith micro-fragments in both scaffolds. Swelling of the GEL/OTL-s (63.54 ± 3.0%) was greater than of ALG/OTL-s (13.36 ± 9.9%) (p < 0.001). The viability of J774.G8 macrophages treated with both scaffolds was statistically similar to the group treated with DMEM only (p > 0.05) and significantly higher than that treated with Triton-X (p < 0.01) at 72 h. Both scaffolds showed approximately 100% growth of MC3T3-E1 osteoblasts by 24 h, similarly to control (p > 0.05). However, by 48 h, only ALG/OTL-s showed growth similar to control (p > 0.05), whereas GEL/OTL showed a significantly lower growth index (p < 0.05). In conclusion, the physicochemical profiles suggest proper interaction between the otoliths and the two developed polymeric 3D scaffolds. Moreover, both materials showed cytocompatibility with J774.G8 macrophages but the growth of MC3T3-E1 osteoblasts was higher when exposed to ALG/OTL-s. These data suggest that sodium alginate/otoliths scaffolds are potential biomaterials to be used in bone regeneration applications. Graphical abstract.

Biological responses of MC3T3-E1 on calcium carbonate coatings fabricated by hydrothermal reaction on titanium

Titainum (Ti) implants have been successfully used in orthopaedic and dental surgery. However, poor early bone tissue integration is still a common cause of implant failure. This could be modulated by improving the material bonding or adhesion directly to the bone by surface roughening and/or a bioresorbable and osteoconductive coating. In this study, we report on the biological behaviours of the Ti substrate with modified surface roughness and/or a calcium carbonate (CaCO₃) coating. The roughened Ti surface was prepared using an acid etching reaction, and the CaCO₃ coating on the substrates was synthesized by the hydrothermal treatment of Ti in calcium citrate complexes. This study demonstrates that surface roughening of Ti alone does not improve the biological response of the MC3T3-E1 cells, but a CaCO₃ coating on the smooth Ti surface increases cell responses, and these effects are further enhanced by the combination of coating a roughened Ti surface with CaCO₃. The larger the cell area, the greater the cell proliferation and increased bone-like nodule formation were observed on the CaCO₃ coating of the roughened Ti surface. This observation was also supported by a higher ALP value. The cell behaviours found in the current study further support the development of CaCO₃ coatings towards clinical application.

Leaching mechanism of bioapatite in carbonate-saturated water

Bioapatite, the main inorganic component of bone, is similar to hydroxyapatite (HAp, Ca₅[PO₄]₃(OH)) having some [CO₃]²⁻ content which plays an important role in leaching/precipitation processes in many biological lesions.

Review on titanium and titanium based alloys as biomaterials for orthopaedic applications

Variety of implant materials have been employed in various disciplines of medical science depending on the requirement of a particular application. Metals, alloys, ceramics, and polymers are the commonly used biomaterials. The main focus of this study is to review the various structural and microstructural properties of titanium and titanium based alloys used as orthopaedic implants. Orthopaedic implants need to possess certain important qualities to ensure their safe and effective use. These properties like the biocompatibility, relevant mechanical properties, high corrosion and wear resistance and osseointegration are summarized in this review. Various attempts to improve upon these properties like different processing routes, surface modifications have also been inculcated in the paper to provide an insight into the extent of research and effort that has been put into developing a highly superior titanium orthopaedic implant.