Bone Regeneration Associated with Nontherapeutic and Therapeutic Surface Coatings for Dental Implants in Osteoporosis

Novel Nonthermal Atmospheric Plasma Irradiation of Titanium Implants Promotes Osteogenic Effect in Osteoporotic Conditions

Osteoporosis is a metabolic disease characterized by bone density and trabecular bone loss. Bone loss may affect dental implant osseointegration in patients with osteoporosis. To promote implant osseointegration in osteoporotic patients, we further used a nonthermal atmospheric plasma (NTAP) treatment device previously developed by our research group. After the titanium implant (Ti) is placed into the device, the working gas flow and the electrode switches are turned on, and the treatment is completed in 30 s. Previous studies showed that this NTAP device can remove carbon contamination from the implant surface, increase the hydroxyl groups, and improve its wettability to promote osseointegration in normal conditions. In this study, we demonstrated the tremendous osteogenic enhancement effect of NTAP-Ti in osteoporotic conditions in rats for the first time. Compared to Ti, the proliferative potential of osteoporotic bone marrow mesenchymal stem cells on NTAP-Ti increased by 180% at 1 day (P = 0.004), while their osteogenic differentiation increased by 149% at 14 days (P < 0.001). In addition, the results indicated that NTAP-Ti significantly improved osseointegration in osteoporotic rats in vivo. Compared to the Ti, the bone volume fraction (BV/TV) and trabecular number (Tb.N) values of NTAP-Ti in osteoporotic rats, respectively, increased by 18% (P < 0.001) and 25% (P = 0.007) at 6 weeks and the trabecular separation (Tb.Sp) value decreased by 26% (P = 0.02) at 6 weeks. In conclusion, this study proved a novel NTAP irradiation titanium implant that can significantly promote osseointegration in osteoporotic conditions.

Strategies for Improving Impaired Osseointegration in Compromised Animal Models

Implant osseointegration is reduced in patients with systemic conditions that compromise bone quality, such as osteoporosis, disuse syndrome, and type 2 diabetes. Studies using rodent models designed to mimic these compromised conditions demonstrated reduced bone-to-implant contact (BIC) or a decline in bone mineral density. These adverse effects are a consequence of disrupted intercellular communication. A variety of approaches have been developed to compensate for the altered microenvironment inherent in compromised conditions, including the use of biologics and implant surface modification. Chemical and physical modification of surface properties at the microscale, mesoscale, and nanoscale levels to closely resemble the surface topography of osteoclast resorption pits found in bone has proven to be a highly effective strategy for improving implant osseointegration. The addition of hydrophilicity to the surface further enhances osteoblast response at the bone-implant interface. These surface modifications, applied either alone or in combination, improve osseointegration by increasing proliferation and osteoblastic differentiation of osteoprogenitor cells and enhancing angiogenesis while modulating osteoclast activity to achieve net new bone formation, although the specific effects vary with surface treatment. In addition to direct effects on surface-attached cells, the communication between bone marrow stromal cells and immunomodulatory cells is sensitive to these surface properties. This article reports on the advances in titanium surface modifications, alone and in combination with novel therapeutics in animal models of human disease affecting bone quality. It offers clinically translatable perspectives for clinicians to consider when using different surface modification strategies to improve long-term implant performance in compromised patients. This review supports the use of surface modifications, bioactive coatings, and localized therapeutics as pragmatic approaches to improve BIC and enhance osteogenic activity from both structural and molecular standpoints.

Impact of Osteoporosis on Autogenous Bone Graft Resorption

BACKGROUND

Osteoporosis is a common disorder that is characterized by decreased bone density and increased bone resorption. This bone resorption may affect the grafted bone during the maxillofacial reconstruction.

PURPOSE

This study aimed to measure the association between osteoporosis and resorption of anterior iliac crest bone grafts used to reconstruct the atrophic anterior maxillae.

STUDY DESIGN, SETTING, SAMPLE

This prospective cohort study included female patients requiring bone augmentation of the anterior maxilla. Patients with a ridge width of <4 mm and ridge height of >7 mm were enrolled in the study. Exclusion criteria were chronic use of corticosteroids or intravenous bisphosphonates, history of maxillofacial radiation therapy, current smoking, and underlying conditions contributing to bone metabolism (eg, hyperparathyroidism, chronic renal failure, and hypophosphatemia).

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

Osteoporosis status was a predictor variable. Patients were allocated to the osteoporosis or control group based on T-scores obtained by dual-energy x-ray absorptiometry. Mean T-scores ≤ -2.5 were assigned to the osteoporosis group.

MAIN OUTCOME VARIABLE(S)

The outcome variable was graft resorption, defined as the difference in ridge width between measurements made immediately (T1) and 6 months postoperatively (T2) using cone-beam computed tomography.

COVARIATES

Patient age, preoperative (T0) bone width, and the amount of bone augmentation, defined as the differences in ridge width between measurements made preoperatively (T0) and immediately after grafting (T1), were covariates of this study.

ANALYSES

Descriptive, analytic, and general linear models were computed. Statistical significance was set a P < .05.

RESULTS

Thirty-two patients were included in the study (15 in the osteoporosis group and 17 in the control group). The amount of graft resorption at 6 months after grafting was 2.57 ± 0.59 mm in the osteoporosis group and 0.97 ± 0.59 mm in the control group (P < .001). A significant correlation was found between the mean T-score and graft resorption 6 months after grafting (P < .001).

CONCLUSION AND RELEVANCE

A significant correlation was observed between osteoporosis and graft resorption in the anterior maxilla after 6 months.

The Potential Therapeutic Effects of Platelet-Derived Biomaterials on Osteoporosis: A Comprehensive Review of Current Evidence

Osteoporosis is a chronic multifactorial condition that affects the skeletal system, leading to the deterioration of bone microstructure and an increased risk of bone fracture. Platelet-derived biomaterials (PDBs), so-called platelet concentrates, such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF), have shown potential for improving bone healing by addressing microstructural impairment. While the administration of platelet concentrates has yielded positive results in bone regeneration, the optimal method for its administration in the clinical setting is still debatable. This comprehensive review aims to explore the systemic and local use of PRP/PRF for treating various bone defects and acute fractures in patients with osteoporosis. Furthermore, combining PRP/PRF with stem cells or osteoinductive and osteoconductive biomaterials has shown promise in restoring bone microstructural properties, treating bony defects, and improving implant osseointegration in osteoporotic animal models. Here, reviewing the results of in vitro and in vivo studies, this comprehensive evaluation provides a detailed mechanism for how platelet concentrates may support the healing process of osteoporotic bone fractures.

Do Systemic Diseases and Medications Influence Dental Implant Osseointegration and Dental Implant Health? An Umbrella Review

The aim of this umbrella review is to evaluate what are the most common medications and systemic diseases that can affect bone-implant integration, the success rate and survival rate of dental implants, peri-implant tissue health, and implant loss. Systematic reviews, with meta-analysis or not, about how systemic diseases and medications influence dental implant osseointegration, survival rate, success rate, and peri-implant diseases, published only in the English language, are electronically searched across the most important scientific databases. The present umbrella review includes eight systematic reviews, and osteoporosis and diabetes are the most investigated pathologies. Systemic diseases, such as neurologic disorders, HIV, hypothyroidism, cardiovascular diseases, and drugs, such as beta blockers, anti-hypertensives, or diuretics do not show a decreased rate of implant osseointegration. It seems that drugs, such as proton-pump inhibitors (PPIs) or serotonin reuptake inhibitors (SSRIs), negatively affect implant osseointegration. Few studies compare the effects of drugs and systemic diseases on the parameters considered in this overview. It is important to underline how the results of this review need to be validated with subsequent and more reviews.

Strontium-doping promotes bone bonding of titanium implants in osteoporotic microenvironment

Osteoporosis is a major challenge to oral implants, and this study focused on improving the osseointegration ability of titanium (Ti) implants in osteoporosis environment via surface modification, including doping of strontium ion and preparation of nanoscale surface feature. Our previous studies have shown that strontium (Sr) ions can enhance osteogenic activity. Therefore, we aimed to comprehensively evaluate the effect of hydrothermal treatment of Sr-doped titanium implant coating on bone-binding properties in the microenvironment of osteoporosis in this study. We fabricated Sr-doped nanocoating (AHT-Sr) onto the surface of titanium implants via hydrothermal reaction. The rough Sr-doping had good biological functions and could apparently promote osteogenic differentiation of osteoporotic bone marrow mesenchymal stem cells (OVX-BMSCs). Most importantly, AHT-Sr significantly promoted bone integration in the osteoporosis environment. This study provides an effective approach to implant surface modification for better osseointegration in an osteoporotic environment.

Bioactive coatings with anti-osteoclast therapeutic agents for bone implants: Enhanced compliance and prolonged implant life

The use of therapeutic agents that inhibit bone resorption is crucial to prolong implant life, delay revision surgery, and reduce the burden on the healthcare system. These therapeutic agents include bisphosphonates, various nucleic acids, statins, proteins, and protein complexes. Their use in systemic treatment has several drawbacks, such as side effects and insufficient efficacy in terms of concentration, which can be eliminated by local treatment. This review focuses on the incorporation of osteoclast inhibitors (antiresorptive agents) into bioactive coatings for bone implants. The ability of bioactive coatings as systems for local delivery of antiresorptive agents to achieve optimal loading of the bioactive coating and its release is described in detail. Various parameters such as the suitable concentrations, release times, and the effects of the antiresorptive agents on nearby cells or bone tissue are discussed. However, further research is needed to support the optimization of the implant, as this will enable subsequent personalized design of the coating in terms of the design and selection of the coating material, the choice of an antiresorptive agent and its amount in the coating. In addition, therapeutic agents that have not yet been incorporated into bioactive coatings but appear promising are also mentioned. From this work, it can be concluded that therapeutic agents contribute to the biocompatibility of the bioactive coating by enhancing its beneficial properties.

Does the serum level of vitamin D affect marginal bone loss around dental implants?

Vitamin D is effective in bone healing. The aim of this study was to assess marginal bone loss (MBL) around dental implants in patients with sufficient and insufficient serum levels of vitamin D. This was a prospective cohort study with a pre-protocol population. Patients who underwent dental implantation in the first or second molar region and had a long-cone peri-apical digital radiograph taken at the time of loading and 12 months later were studied. Patients were assigned to one of three groups based on their serum vitamin D level: group 1, the serum level of vitamin D was deficient, group 2 insufficient, and group 3 sufficient. The marginal bone level change from immediately after loading to 12 months later was considered as MBL. Analysis of variance (ANOVA) was applied to compare MBL between the three groups. Ninety patients were included (30 in each group). The mean MBL was 1.38 ± 0.33 mm in group 1, 0.89 ± 0.16 mm in group 2, and 0.78 ± 0.12 mm in group 3. Analysis of the data demonstrated a significant difference in the mean MBL among the three groups (P < 0.001). There was a correlation between MBL and vitamin D serum levels (P < 0.001). It appears that a low serum level of vitamin D may be associated with increased MBL.

Intraosseous Injection of Calcium Phosphate Polymer-Induced Liquid Precursor Increases Bone Density and Improves Early Implant Osseointegration in Ovariectomized Rats

PURPOSE

Osteoporosis, due to bone loss and structural deterioration, is a risk factor for dental implant failure, as it impedes initial stability and osseointegration. We aim to assess the effects of calcium phosphate polymer-induced liquid precursor (CaP-PILP) treatment, which significantly increases bone density and improves early implant osseointegration in ovariectomized rats.

METHODS

In this study, CaP-PILP was synthesized and characterized through TEM, FTIR and XRD. A rat model of osteoporosis was generated by ovariectomy. CaP-PILP or hydroxyapatite (HAP, negative control) was injected into the tibia, and the resulting changes in bone quality were determined. Further, implants were installed in the treated tibias, and implantation characteristics were assessed after 4 weeks.

RESULTS

The CaP-PILP group had superior bone repair. Importantly, CaP-PILP had excellent properties, similar to those of normal bone, in terms of implant osseointegration. In vivo experiment displayed that CaP-PILP group had better bone contact rate (65.97±3.176) than HAP and OVX groups. Meanwhile, a mound of mature and continuous new bone formed. Moreover, the values of BIC and BA showed no significant difference between the CaP-PILP group and the sham group.

CONCLUSION

In summary, CaP-PILP is a promising material for application in poor-quality bones to improve implant success rates in patients with osteoporosis. This research provides new perspectives on the application of nano-apatite materials in bone repair.

Histomorphometric Evaluation of Peri-Implant Bone Response to Intravenous Administration of Zoledronate (Zometa®) in an Osteoporotic Rat Model

We evaluated the response to peri-implant bone placed in the femoral condyle of osteoporotic rats, following intravenous zoledronate (ZOL) treatment in three settings: pre-implantation (ZOL-Pre), post-implantation (ZOL-Post), and pre- + post-implantation (ZOL-Pre+Post). Twenty-four female Wistar rats were ovariectomized (OVX). After 12 weeks, the rats received titanium implants in the right femoral condyle. ZOL (0.04 mg/kg, weekly) was administered to six rats 4 weeks pre-implantation and was stopped at implant placement. To another six rats, ZOL was given post-implantation and continued for 6 weeks. Additional six rats received ZOL treatment pre- and post-implantation. Control animals received weekly saline intravenous injections. At 6 weeks post-implantation, samples were retrieved for histological evaluation of the percentage of bone area (%BA) and of the percentage of bone-to-implant contact (%BIC). BA% for ZOL-Pre (29.6% ± 9.0%) and ZOL-Post (27.9% ± 5.6%) rats were significantly increased compared to that of the controls (17.3% ± 3.9%, p < 0.05). In contrast, ZOL-Pre+Post rats (20.4% ± 5.0%) showed similar BA% compared to Saline controls (p = 0.731). BIC% revealed a significant increase for ZOL-Post (65.8% ± 16.9%) and ZOL-Pre+Post (68.3% ± 10.0%) rats compared with that of Saline controls (43.3% ± 9.6%, p < 0.05), while ZOL-Pre rats (55.6% ± 19%) showed a BIC% comparable to that of Saline controls (p = 0.408). Our results suggest that receiving intravenous ZOL treatment before or after implant placement enhances peri-implant bone responses in terms of bone area. However, the effect of different ZOL treatment regimens on BIC% was found to be inconclusive.

Osteogenesis-Related Gene Expression and Guided Bone Regeneration of a Strontium-Doped Calcium-Phosphate-Coated Titanium Mesh

Guided bone regeneration using a perforated titanium membrane is actively used in oral and orthopedic surgeries to provide space for the subsequent filling of a new bone in the case of bone defects and to achieve proper bone augmentation and reconstruction. The surface modification of a titanium membrane using a strontium-substituted calcium phosphate coating has become a popular trend to provide better bioactivity and biocompatibility on the membrane for improving the bone regeneration because strontium can stimulate not only the differentiation of osteoblasts but also inhibit the differentiation of osteoclasts. The strontium-doped calcium phosphate coating on the titanium mesh was formed by the cyclic precalcification method, and its effects on bone regeneration were evaluated by in vitro analysis of osteogenesis-related gene expression and in vivo evaluation of osteogenesis of the titanium mesh using the rat calvarial defect model in this study. It was identified that the strontium-doped calcium phosphate-treated mesh showed a higher expression of all genes related to osteogenesis in the osteoblast cells and resulted in new bone formation with better osseointegration with the mesh in the rat calvarial defect, in comparison with the results of untreated and calcium phosphate-treated meshes.

Does the implant-abutment interface interfere on marginal bone loss? A systematic review and meta-analysis

The objective of this systematic review was to compare the conical internal connection (IC) with the external hexagonal connection (EH) on the occurrence of marginal bone loss (ΔMBL). Different databases were used to carry out the selection of the elected studies. The studies were judged according to the risk of bias as "high", "low" and "unclear" risk. For the meta-analysis we included only studies that could extract the data of ΔMBL, survival rate (SR) and probing depth (PD). No statistically significant differences were found for ΔMBL data at one, three- and five-year survival rates between implant connections (p <0.05), however statistically significant differences were found for PD between EH and IC implants (1-year follow-up) -0.53 [95%CI -0.82 to -0.24, p = 0.0004]. This present systematic review demonstrated that there are no significant differences between IC and EH implants for both ΔMBL and SR at 1, 3 e 5 years after functional loading, although better PD values were observed for implants pertaining to the IC connections. Considering the high heterogeneity, more well-delineated, randomized clinical trials should be conducted.

Bone Regeneration Using Antiosteoporotic Drugs in Adjunction with Bone Grafting: A Meta-Analysis

The aim of this review was to systematically assess bone regeneration by using antiosteoporotic drugs in adjunction with bone grafting compared with controls (bone grafting without the administration of antiosteoporotic drugs). The review also evaluated statistical differences in the effect between systemic and local routes of drugs. Also, the effect of type of drugs (anticatabolic vs. anabolic) was subevaluated. PubMed and EMBASE (via OvidSP) resulted in inclusion of 60 animal studies. The studies were assessed for reporting quality and risk of bias. Outcome data from selected studies were categorized as either experimental (bone grafting with the administration of antiosteoporotic drugs) or control. Meta-analysis of selected studies was done for these outcomes: histomorphometrical bone area (BA%) and micro-CT bone volume (BV%). In this review, several animal models (52 healthy, 6 osteoporotic, and 2 both conditions) were subjected to examine the effect of antiosteoporotic drugs on bone grafting, with a predominant use of rodent species. Assessment indicates poor reporting quality and unclear risk of bias in the majority of studies. Random-effects meta-analysis revealed a significant increase in overall BA% (mean difference [MD]: 2.6, confidence interval [CI]: 2.25 to 2.92) and BV% (MD: 0.12, CI: 0.05 to 0.19) due to osteoporotic drug treatment compared with controls. For subgroups, both routes of antiosteoporotic drug administration showed similar effects on BA%. In contrast, systemic antiosteoporotic drug administration led to significantly higher BV% (MD: 6.75, CI: 5.30 to 8.19) compared with local administration (MD: 0.02, CI: -0.03 to 0.08). Further, administration of anabolic drugs significantly increased BA% (MD: 5.75, CI: 4.62 to 6.87) compared with anticatabolic drugs (MD: 1.86, CI: 1.47 to 2.26). In conclusion, both histomorphometrical and micro-CT scan analysis indicated an overall effect of using the antiosteoporotic drugs toward bone regeneration in adjunction with grafting. However, not all studies showed a positive effect and the present results need to be applied with care, as the included papers showed experimental heterogeneity for animal models. Further (pre)clinical research is warranted to explore whether drug-based strategies can be an effective adjunctive with bone grafting. Impact Statement The aim of this meta-analysis was to assess whether antiosteoporotic drugs can promote bone regeneration in adjunction with bone grafting by using preclinical animal models. Although the majority of included studies indicated poor reporting quality and unclear risk of bias, an overall positive effect of the antiosteoporotic drugs toward bone regeneration related to bone grafts can be highlighted.

Transcriptomic profiling of tantalum metal implant osseointegration in osteopenic patients

OBJECTIVES

The long-term success of dental implants is established by literature. Although clinically well defined, the complex genetic pathways underlying osseointegration have not yet been fully elucidated. Furthermore, patients with osteopenia/osteoporosis are considered to present as higher risk for implant failure. Porous tantalum trabecular metal (PTTM), an open-cell porous biomaterial, is suggested to present enhanced biocompatibility and osteoconductivity. The goal of this study was to evaluate the expression patterns of a panel of genes closely associated with osteogenesis and wound healing in osteopenic patients receiving either traditional titanium (Ti) or PTTM cylinders to assess the pathway of genes activation in the early phases of osseointegration.

MATERIAL AND METHODS

Implant cylinders made of Ti and PTTM were placed in osteopenic volunteers. At 2- and 4 weeks of healing, one Ti and one PTTM cylinder were removed from each subject for RT-PCR analysis using osteogenesis PCR array.

RESULTS

Compared to Ti, PTTM-associated bone displayed upregulation of bone matrix proteins, BMP/TGF tisuperfamily, soluble ligand and integrin receptors, growth factors, and collagen genes at one or both time points. Histologically, PTTM implants displayed more robust osteogenesis deposition and maturity when compared to Ti implants from the same patient.

CONCLUSIONS

Our results indicate that PTTM properties could induce an earlier activation of genes associated with osteogenesis in osteopenic patients suggesting that PTTM implants may attenuate the relative risk of placing dental implants in this population.

Loading icariin on titanium surfaces by phase-transited lysozyme priming and layer-by-layer self-assembly of hyaluronic acid/chitosan to improve surface osteogenesis ability

Purpose

Icariin (ICA) is one of the main active constituents of Herba Epimedii for improving osteogenesis. It is necessary to create a simple and efficient method to load ICA onto the surface of titanium (Ti) implant. The purpose of this study was to establish a local ICA delivery system via a layer-by-layer (LbL) self-assembly system on phase-transited lysozyme (PTL)-primed Ti surface.

Materials and methods

A PTL nanofilm was first firmly coated on the pristine Ti. Then, the ICA-loaded hyaluronic acid/chitosan (HA/CS) multilayer was applied via the LbL system to form the HA/CS-ICA surface. This established HA/CS-ICA surface was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measurement. The ICA release pattern of the HA/CS-ICA surface was also examined. MC3T3-E1 osteoblast culture test and a rat model were used to evaluate the effects of the HA/CS-ICA surface in vitro and in vivo.

Results

SEM, XPS and contact angle measurement demonstrated successful fabrication of the HA/CS-ICA surface. The HA/CS-ICA surfaces with different ICA concentrations revealed a controlled release profile of ICA during a 2-week monitoring span. Osteoblasts grown on the coated substrates displayed higher adhesion, viability, proliferation and ALP activity than those on the polished Ti surface. Furthermore, in vivo histological evaluation revealed much obvious bone formation in the ICA-coated group by histological staining and double fluorescent labeling at 2 weeks after implantation.

Conclusion

The present study demonstrated that ICA-immobilized HA/CS multilayer on the PTL-primed Ti surface had a sustained release pattern of ICA which could promote the osteogenesis of osteoblasts in vitro and improve early osseointegration in vivo. This study provides a novel method for creating a sustained ICA delivery system to improve osteoblast response and osseointegration.

A Prospective, Controlled, Multicenter Study to Evaluate the Clinical Outcome of Implant Treatment in Women with Osteoporosis/Osteopenia: 5-Year Results

The impact of osteoporosis on implant treatment is still a matter of debate in the scientific community, as it may possibly lead to higher failure rates. As long-term controlled trials are missing, the aim of this study was to verify the long-term outcome of implants placed in patients with systemic osteoporosis. Postmenopausal women in need of implants underwent bone mineral density measurements in hip and spine, using dual X-ray absorptiometry scans. Based on T-scores, they were divided into 2 groups: group O (osteoporosis group) with a T-score ≤-2 or group C (control group) with a T-score of ≥-1. Implants were placed in a 2-stage manner and loaded 4 to 8 wk after abutment surgery. Six months after loading and thereafter yearly, clinical and radiographical parameters were assessed. In total, 148 implants were placed in 48 patients (mean age: 67 y [range, 59-83]). Sixty-three implants were placed in 20 patients (group O) and 85 implants in 28 patients (group C). After 5 y, 117 implants (38 in group O and 79 in the group C) in 37 patients were assessed. Cumulative survival rate on an implant level was 96.5% (group O: 91.5%; group C: 100.0% [ P < 0.05]) and 95.7% (group O: 89.2%; group C: 100.0% [ P > 0.05]) on a patient level. The overall marginal bone-level alterations, after 5 y of loading, were -0.09 ± 0.78 mm (group O: -0.15 ± 0.50 mm; group C: -0.06 ± 0.89 mm) on an implant level and -0.09 ± 0.54 mm (group O: -0.18 ± 0.43 mm; group C: 0.06 ± 0.58 mm) on a patient level ( P > 0.05). Oral implant therapy in osteoporotic patients is a reliable treatment option with comparable osseointegration rates, implant survival, and marginal bone-level alterations after 5 y of functional loading (ClinicalTrials.gov NCT00745121).

Antiosteoporotic Drugs to Promote Bone Regeneration Related to Titanium Implants: A Systematic Review and Meta-Analysis

IMPACT STATEMENT

This meta-analysis was to investigate literature on the administration of antiosteoporotic drugs as an effective adjunct therapy for implant osseointegration using in vivo animal models.

The effect of surface immobilized NBD peptide on osteoclastogenesis of rough titanium plates in vitro and osseointegration of rough titanium implants in ovariectomized rats in vivo

Successful osseointegration in dental implants depends on balanced activation of osteoclasts and osteoblasts. Osteoporosis up-regulates osteoclast activity, so it is desirable to find effective interventions to inhibit osteoclastogenesis and enhance the osseointegration of implants under these conditions. It has been reported that the NF-κB essential modulator (NEMO)-binding domain (NBD) peptide can prevent osteoclast formation and bone resorption. In this study, we conjugated NBD peptide onto the surface of rough pure titanium (Ti) using the layer by layer technique. We analyzed the surface characteristics and determined the successful NBD integration by the presence of trivial granular structures, increased S elements and hydrophilia. Importantly, we first reported that Ti surface-conjugated NBD peptide retained its inhibitory effects on osteoclastogenesis by reducing osteoclast sealing zone formation and function. These effects were mediated by a reduction in NFATc1 expression, which in turn regulated integrin ανβ₃ and MMP9 by targeting the P65 signaling pathway. In vivo TRAP staining suggested NBD-coating decreased osteoclast formation with less pseudopodia. Micro-CT and histomorphometric analysis demonstrated that NBD-coating enhanced pronounced osseointegration in vivo in ovariectomized rats. This study holds great promise for in vivo use of immobilized NBD peptide and offers an effective therapeutic approach to select more suitable Ti-implant surface modifications for improving implant osseointegration in osteoporotic patients.

Successful osseointegration in dental implants depends on balanced activation of osteoclasts and osteoblasts.

Methods to Improve Osseointegration of Dental Implants in Low Quality (Type-IV) Bone: An Overview

Nowadays, dental implants have become more common treatment for replacing missing teeth and aim to improve chewing efficiency, physical health, and esthetics. The favorable clinical performance of dental implants has been attributed to their firm osseointegration, as introduced by Brånemark in 1965. Although the survival rate of dental implants over a 10-year observation has been reported to be higher than 90% in totally edentulous jaws, the clinical outcome of implant treatment is challenged in compromised (bone) conditions, as are frequently present in elderly people. The biomechanical characteristics of bone in aged patients do not offer proper stability to implants, being similar to type-IV bone (Lekholm &amp; Zarb classification), in which a decreased clinical fixation of implants has been clearly demonstrated. However, the search for improved osseointegration has continued forward for the new evolution of modern dental implants. This represents a continuum of developments spanning more than 20 years of research on implant related-factors including surgical techniques, implant design, and surface properties. The methods to enhance osseointegration of dental implants in low quality (type-IV) bone are described in a general manner in this review.

Simple 3,4-Dihydroxy-L-Phenylalanine Surface Modification Enhances Titanium Implant Osseointegration in Ovariectomized Rats

Osteoporosis presents a challenge to the long-term success of osseointegration of endosseous implants. The bio-inspired 3,4-dihydroxy-L-phenylalanine (Dopa) coating is widely used as a basic layer to bind osteogenetic molecules that may improve osseointegration. To date, little attention has focused on application of Dopa alone or binding inhibitors of bone resorption in osteoporosis. Local use of a bisphosphonate such as zoledronic acid (ZA), an inhibitor of osteoclast-mediated bone resorption, has been proven to improve implant osseointegration. In this study, ovariectomized rats were divided into four groups and implanted with implants with different surface modifications: sandblasted and acid-etched (SLA), SLA modified with Dopa (SLA-Dopa), SLA modified with ZA (SLA-ZA), and SLA modified with Dopa and ZA (SLA-Dopa + ZA). Measurement of removal torque, micro-computed tomography and histology revealed a greater extent of bone formation around the three surface-modified implants than SLA-controls. No synergistic effect was observed for combined Dopa + ZA coating. Microarray analysis showed the Dopa coating inhibited expression of genes associated with osteoclast differentiation, similarly to the mechanism of action of ZA. Simple Dopa modification resulted in a similar improvement in osseointegration compared to ZA. Thus, our data suggest simple Dopa coating is promising strategy to promote osseointegration of implants in patients with osteoporosis.

Increasing the Stability of Dental Implants: the Concept of Osseodensification

One of the most important factors that affect osseointegration is the primary stability of the implant. Dental implants inserted at the posterior region of the maxilla exhibit the lowest success rates as the low density bone in this area often jeopardize rigid fixation of the implant. Many surgical techniques have been developed to increase the primary stability of an implant placed in low density bone, such as bicortical fixation of the implant, undersized preparation of the implant bed and bone condensation by the use of osteotomes. A new promising technique, named osseodensification, has been recently developed that creates an autograft layer of condensed bone at the periphery of the implant bed by the aid of specially designed burs rotating in a clockwise and anti-clockwise direction. The purpose of this review is to emphasize that implant primary stability is strongly influenced by the surgical technique, to quote and briefly analyse the various surgical procedures laying weight to osseodensification procedure.

Dual-Functionalized Graphene Oxide Based siRNA Delivery System for Implant Surface Biomodification with Enhanced Osteogenesis

Surface functionalization by small interfering RNA (siRNA) is a novel strategy for improved implant osseointegration. A gene delivery system with safety and high transfection activity is a crucial factor for an siRNA-functionalized implant to exert its biological function. To this end, polyethylene glycol (PEG) and polyethylenimine (PEI) dual-functionalized graphene oxide (GO; nGO-PEG-PEI) may present a promising siRNA vector. In this study, nanosized nGO-PEG-PEI was prepared and optimized for siRNA delivery. Titania nanotubes (NTs) fabricated by anodic oxidation were biomodified with nGO-PEG-PEI/siRNA by cathodic electrodeposition, designated as NT-GPP/siRNA. NT-GPP/siRNA possessed benign cytocompatibility, as evaluated by cell adhesion and proliferation. Cellular uptake and knockdown efficiency of the NT-GPP/siRNA were assessed by MC3T3-E1 cells, which exhibited high siRNA delivery efficiency and sustained target gene silencing. Casein kinase-2 interacting protein-1 (Ckip-1) is a negative regulator of bone formation. siRNA-targeting Ckip-1 (siCkip-1) was introduced to the implant, and a series of in vitro and in vivo experiments were carried out to evaluate the osteogenic capacity of NT-GPP/siCkip-1. NT-GPP/siCkip-1 dramatically improved the in vitro osteogenic differentiation of MC3T3-E1 cells in terms of improved osteogenesis-related gene expression, and increased alkaline phosphatase (ALP) production, collagen secretion, and extracellular matrix (ECM) mineralization. Moreover, NT-GPP/siCkip-1 led to apparently enhanced in vivo osseointegration, as indicated by histological staining and EDX line scanning. Collectively, these findings suggest that NT-GPP/siRNA represents a practicable and promising approach for implant functionalization, showing clinical potential for dental and orthopedic applications.

Dental implants in patients with osteoporosis: a systematic review with meta-analysis

There is currently no consensus regarding the survival rate of osseointegrated implants in patients with osteoporosis. A systematic review with meta-analysis was performed to evaluate the survival rate of implants in such patients. The PubMed/MEDLINE, Web of Science, Cochrane Library, and SciELO databases were used to identify articles published up to September 2016. The systematic review was performed in accordance with PRISMA/PICO requirements and the risk of bias was assessed (Australian National Health and Medical Research Council scale). The relative risk (RR) of implant failure and mean marginal bone loss were analyzed within a 95% confidence interval (CI). Fifteen studies involving 8859 patients and 29,798 implants were included. The main outcome of the meta-analysis indicated that there was no difference in implant survival rate between patients with and without osteoporosis, either at the implant level (RR 1.39, 95% CI 0.93-2.08; P=0.11) or at the patient level (RR 0.98, 95% CI 0.50-1.89; P=0.94). However, the meta-analysis for the secondary outcome revealed a significant difference in marginal bone loss around implants between patients with and without osteoporosis (0.18mm, 95% CI 0.05-0.30, P=0.005). Data heterogeneity was low. An increase in peri-implant bone loss was observed in the osteoporosis group. Randomized and controlled clinical studies should be conducted to analyze possible biases.

Theranostic Bioabsorbable Bone Fixation Plate with Drug-Layered Double Hydroxide Nanohybrids

A bioabsorbable polymeric bone plate enabled with both diagnostic and therapeutic functionalities (radiopacity and sustained drug release, respectively) is proposed. To this end, a drug-inorganic nanohybrid (RS-LDH) is examined as a theranostic agent by intercalating an anti-resorptive bone remodeling drug, risedronate (RS) into a layered double hydroxide (LDH) via an ion-exchange reaction. The RS-LDH is prepared as a sheet with a biodegradable polymer, poly(lactic-co-glycolic acid), and is then attached onto the clinically approved bioabsorbable bone plate to produce the theranostic plate. Because of the presence of the metals in the LDH, the theranostic plate results in discernible in vivo X-ray images for up to four weeks after implantation. Concurrently, bone regeneration is also significantly improved compared with the other control groups, likely because of this material's sustained drug-release property. The theranostic plate is also largely biocompatible, similar to the plate already approved for clinical use. It is concluded that the combination of a biodegradable bone plate with RS-LDH nanohybrids can constitute a promising system with theranostic ability in both X-ray diagnosis and expedited bone repair.

The effects of implant topography on osseointegration under estrogen deficiency induced osteoporotic conditions: Histomorphometric, transcriptional and ultrastructural analysis

Compromised bone quality and/or healing in osteoporosis are recognised risk factors for impaired dental implant osseointegration. This study examined the effects of (1) experimentally induced osteoporosis on titanium implant osseointegration and (2) the effect of modified implant surface topography on osseointegration under osteoporosis-like conditions. Machined and micro-roughened surface implants were placed into the maxillary first molar root socket of 64 ovariectomised and sham-operated Sprague-Dawley rats. Subsequent histological and SEM observations showed tissue maturation on the micro-rough surfaced implants in ovariectomised animals as early as 3days post-implantation. The degree of osseointegration was also significantly higher around the micro-rough implants in ovariectomised animals after 14days of healing although by day 28, similar levels of osseointegration were found for all test groups. The micro-rough implants significantly increased the early (day 3) gene expression of alkaline phosphatase, osteocalcin, receptor activator of nuclear factor kappa-B ligand and dentin matrix protein 1 in implant adherent cells. By day 7, the expression of inflammatory genes decreased while the expression of the osteogenic markers increased further although there were few statistically significant differences between the micro-rough and machined surfaces. Osteocyte morphology was also affected by estrogen deficiency with the size of the cells being reduced in trabecular bone. In conclusion, estrogen deficiency induced osteoporotic conditions negatively influenced the early osseointegration of machined implants while micro-rough implants compensated for these deleterious effects by enhancing osteogenic cell differentiation on the implant surface.

STATEMENT OF SIGNIFICANCE

Lower bone density, poor bone quality and osseous microstructural changes are all features characteristic of osteoporosis that may impair the osseointegration of dental implants. Using a clinically relevant trabecular bone model in the rat maxilla, we demonstrated histologically that the negative effects of surgically-induced osteoporosis on osseointegration could be ameliorated by the biomaterial's surface topography. Furthermore, gene expression analysis suggests this may be a result of enhanced osteogenic cell differentiation on the implant surface.

Dental implants in patients affected by systemic diseases

Several systemic diseases (and relative medications) have been reported to impair or in some cases complicate dental implant surgery. In broader terms, when dealing with patients suffering from systemic diseases, the monitoring of the medical condition and of the related post-operative complications is of great importance in order to avoid risks which could jeopardise the health of the patient. In this review, the available evidence on implant survival/success, as well as relevant surgical recommendations in patients affected by systemic diseases, are evaluated and when possible, practical suggestions for the clinician are provided.

Electrochemical Cathodic Polarization, a Simplified Method That Can Modified and Increase the Biological Activity of Titanium Surfaces: A Systematic Review

Background

The cathodic polarization seems to be an electrochemical method capable of modifying and coat biomolecules on titanium surfaces, improving the surface activity and promoting better biological responses.

Objective

The aim of the systematic review is to assess the scientific literature to evaluate the cellular response produced by treatment of titanium surfaces by applying the cathodic polarization technique.

Data, Sources, and Selection

The literature search was performed in several databases including PubMed, Web of Science, Scopus, Science Direct, Scielo and EBSCO Host, until June 2016, with no limits used. Eligibility criteria were used and quality assessment was performed following slightly modified ARRIVE and SYRCLE guidelines for cellular studies and animal research.

Results

Thirteen studies accomplished the inclusion criteria and were considered in the review. The quality of reporting studies in animal models was low and for the in vitro studies it was high. The in vitro and in vivo results reported that the use of cathodic polarization promoted hydride surfaces, effective deposition, and adhesion of the coated biomolecules. In the experimental groups that used the electrochemical method, cellular viability, proliferation, adhesion, differentiation, or bone growth were better or comparable with the control groups.

Conclusions

The use of the cathodic polarization method to modify titanium surfaces seems to be an interesting method that could produce active layers and consequently enhance cellular response, in vitro and in vivo animal model studies.

Magnesium release from mesoporous carriers on endosseus implants does not influence bone maturation at 6 weeks in rabbit bone

OBJECTIVES

The release of magnesium ions (Mg²⁺ ) from titanium surfaces has been shown to boost the initial biological response of peri-implant bone and to increase the biomechanical strength of osseointegration. The objective of the present paper was to investigate if the initial improvement in osseointegration would influence the bone remodeling also during the maturation stage of bone healing.

METHODS

Titanium implants were coated with mesoporous titania layers and either loaded with Mg²⁺ (test group) or left untreated (control group). The implants were inserted in the tibiae of 10 New Zealand White rabbits. Osseointegration was assessed after 6 weeks by means of biomechanical testing (RTQ), non-decalcified histology and histomorphometry (BIC%, BA%, NBA%). The expression of genes involved in the bone formation and remodeling was quantified using qPCR.

RESULTS

Mg²⁺ releasing mesoporous titania coatings showed, on average, higher removal torques and histomorphometrical outcomes (RTQ: 17.2 Ncm vs. 15 Ncm; BIC: 38.8% vs. 32.1%; BA%: 71.6% vs. 64%; NBA% 62.5% vs. 54% for the tests vs the controls); however, the differences were not statistically significant. Three osteogenic markers, osteocalcin (OC), collagen 1 alpha 1 (COL1A1), and alkalin phosphatase (ALPL), were respectively 2-fold, 1.53-fold, and 1.13-fold up-regulated in the control group compared to the test. The expression of COL1A1 was particularly high in both groups, while the biomarkers for remodeling and inflammation showed a low expression in both groups.

SIGNIFICANCE

The results suggested that the initial enhancement in osseointegration induced by magnesium release from mesoporous titania coatings has no detrimental effects during bone maturation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2118-2125, 2017.

Osteophilic properties of bone implant surface modifications in a cassette model on a decorticated goat spinal transverse process

This study comparatively evaluated the osteophilic capacity of 17 different surface modifications (i.e. fourteen different chemical modifications via ceramic coatings and three different physical modifications via surface roughness) for titanium (Ti) surfaces. All surface modifications were subjected to physico-chemical analyses and immersion in simulated body fluid (SBF) for coating stability assessment. Subsequently, a bone conduction chamber cassette model on the goat transverse process was used for comparative in vivo analysis based on bone responses to these different surface modifications after twelve weeks. Histological and histomorphometrical analyses in terms of longitudinal bone-to-implant contact percentage (BIC%), relative bone area (BA%) were investigated within each individual channel and maximum bone height (BH). Characterization of the surface modifications showed significant differences in surface chemistry and surface roughness among the surface modifications. Generally, immersion of the coatings in SBF showed net uptake of calcium by thick coatings (>50μm; plasma-sprayed and biomimetic coatings) and no fluctuations in the SBF for thin coatings (<50μm). The histomorphometrical data set demonstrated that only plasma-sprayed CaP coatings performed superiorly regarding BIC%, BA% and BH compared to un-coated surfaces, irrespective of surface roughness of the latter. In conclusion, this study demonstrated that the deposition of plasma-sprayed CaP coating with high roughness significantly improves the osteophilic capacity of titanium surfaces in a chamber cassette model.

STATEMENT OF SIGNIFICANCE

For the bone implant market, a large number of surface modifications are available on different types of (dental and orthopedic) bone implants. As the implant surface provides the interface at which the biomaterial interacts with the surrounding (bone) tissue, it is of utmost importance to know what surface modification has optimal osteophilic properties. In contrast to numerous earlier studies on bone implant surface modifications with limited number of comparison surfaces, the manuscript by van Oirschot et al. describes the data of in vivo experiments using a large animal model that allows for direct and simultaneous comparison of a large variety of surface modifications, which included both commercially available and experimental surface modifications for bone implants. These data clearly show the superiority of plasma-sprayed hydroxyapatite coatings regarding bone-to-implant contact, bone amount, and bone height.

High-frequency loading positively impacts titanium implant osseointegration in impaired bone

High-frequency loading via whole body vibration promotes bone formation and increases bone strength. Whether this translates to positive titanium implant osseointegration in osteoporotic bone was explored in this animal study. An anabolic effect of not only bisphosphonate treatment but also high-frequency loading on implant osseointegration in osteoporotic bone was observed.

INTRODUCTION

The present study investigated the impact of high-frequency (HF) loading, applied via whole body vibration (WBV), on titanium implant osseointegration in healthy versus ovariectomy-induced compromised versus pharmacologically treated compromised bone.

METHODS

A custom-made Ti implant was inserted into the metaphyseal tibia of 59 rats and left to heal for either 4 or 14 days. Rats were divided into six groups according to their hormonal and mechanical status. WBV, consisting of 10 consecutive frequency steps at an acceleration of 0.3 g, was applied daily for either 4 or 14 days. Tissue samples were processed for quantitative histology at the tibial cortical and medullar level. Data were analyzed by three-way ANOVA and by post hoc pairwise comparisons.

RESULTS

The bone healing response at the interface and surrounding titanium implants was negatively influenced by osteoporotic bone conditions, mainly at the trabecular bone level. Furthermore, the administration of bisphosphonates for preventing the ovariectomy-induced impaired peri-implant response was successful. Finally, the effect of HF WBV loading on the peri-implant bone healing was dependent on the bone condition and was anabolic solely in untreated osteoporotic trabecular bone when applied for an extended period of time.

CONCLUSIONS

The bone healing response to implant installation is compromised in osteoporotic bone conditions, in particular at the trabecular bone compartment. Meanwhile, not only pharmacological treatment but also mechanical loading via HF WBV can exert a positive effect on implant osseointegration in this specific bone micro-environment. The peri-implant cortical bone, however, seems to be less sensitive to HF WBV loading influences.

An experimental study to investigate biomechanical aspects of the initial stability of press-fit implants

Initial fixation of press-fit implants depends on interference fit, surface morphology, and bone material properties. To understand the biomechanical effect of each factor and their interactions, the pull-out strength of seven types of CoCrMo tapered implants, with four different interference fits, three different surface morphologies (low, medium and high roughness), and at two time points (0 and 30 min) were tested in trabecular bone with varying density. The effect of interference fit on pull-out strength depended on the surface morphology and time. In contrast with our expectations, samples with a higher roughness had a lower pull-out strength. We found a similar magnitude of bone damage for the different surface morphologies, but the type of damage was different, with bone compaction versus bone abrasion for low and high frictional surfaces, respectively. This explains a reduced sensitivity of fixation strength to bone mineral density in the latter group. In addition, a reduction in fixation strength after a waiting period only occurred for the low frictional specimens. Our study demonstrates that it is essential to evaluate the interplay between different factors and emphasizes the importance of testing in natural bone in order to optimize the initial stability of press-fit implants.

Recent developments in metabolic bone diseases: a gnathic perspective

Metabolic bone diseases often are asymptomatic and progress sub clinically. Many patients present at a late stage with catastrophic skeletal and extra skeletal complications. In this article, we provide an overview of normal bone remodeling and a synopsis of recent developments in the following conditions: osteoporosis, rickets/osteomalacia, endocrine-induced bone disease, chronic kidney disease-mineral bone disorder and Paget's disease of bone. Our discussion will emphasize the clinical and microscopic manifestations of these diseases in the jaws.