Impact of Dental Implant Surface Modifications on Osseointegration

Bone tissue formation around two titanium implant surfaces placed in bone defects filled with bone substitute material or blood clot: A pilot study

OBJECTIVES

The objective of this study was to evaluate the peri-implant bone tissue formation around titanium implants with different surface treatments, placed in bone defects filled or not with bone substitute material (BSM).

MATERIALS AND METHODS

Ten animals were divided into two groups according to implant surface treatment. In each tibia, a bone defect was created followed by the placement of one implant. On the left tibia, the defect was filled with blood clot (BC), and on the right tibia, the defect was filled with biphasic hydroxyapatite/β-tricalcium-phosphate (HA/TCP) generating four subgroups: BC-N: blood clot and porous surface; BC-A: blood clot and porous-hydrophilic surface; HA/TCP-N: BSM and porous surface; HA/TCP-A: BSM and porous-hydrophilic surface. The animals were submitted to euthanasia 60 days after implant installation. After light-curing resin inclusion, the blocks containing the implant and the bone tissue were stained and evaluated by means of histomorphometry to assess the percentages of bone implant contact (% BIC). Data was normally distributed and the group differences were examined using the parametric tests of Two-Way ANOVA.

RESULTS

The BC-A group presented the higher mean value of BIC (46.43%). The HA/TCP-A group presented the higher mean value of BIC. The porous-hydrophilic surfaces presented better results of BIC when compared to the porous surface in both conditions of defect filling. No statistically significant differences were found among all groups (95% confidence interval and P < .05).

CONCLUSION

According to histomorphometric analysis, after 60-days in a rabbit model, hydrophilic and hydrophobic surfaces have the same behavior in the presence or absence of HA/TCP.

Influence of Titanium Oxide Pillar Array Nanometric Structures and Ultraviolet Irradiation on the Properties of the Surface of Dental Implants-A Pilot Study

Aim: Titanium implants are commonly used as replacement therapy for lost teeth and much current research is focusing on the improvement of the chemical and physical properties of their surfaces in order to improve the osseointegration process. TiO₂, when it is deposited in the form of pillar array nanometric structures, has photocatalytic properties and wet surface control, which, together with UV irradiation, provide it with superhydrophilic surfaces, which may be of interest for improving cell adhesion on the peri-implant surface. In this article, we address the influence of this type of surface treatment on type IV and type V titanium discs on their surface energy and cell growth on them. Materials and methods: Samples from titanium rods used for making dental implants were used. There were two types of samples: grade IV and grade V. In turn, within each grade, two types of samples were differentiated: untreated and treated with sand blasting and subjected to double acid etching. Synthesis of the film consisting of titanium oxide pillar array structures was carried out using plasma-enhanced chemical vapor deposition equipment. The plasma was generated in a quartz vessel by an external SLAN-1 microwave source with a frequency of 2.45 GHz. Five specimens from each group were used (40 discs in total). On the surfaces to be studied, the following determinations were carried out: (a) X-ray photoelectron spectroscopy, (b) scanning electron microscopy, (c) energy dispersive X-ray spectroscopy, (d) profilometry, (e) contact angle measurement or surface wettability, (f) progression of contact angle on applying ultraviolet irradiation, and (g) a biocompatibility test and cytotoxicity with cell cultures. Results: The application of ultraviolet light decreased the hydrophobicity of all the surfaces studied, although it did so to a greater extent on the surfaces with the studied modification applied, this being more evident in samples manufactured in grade V titanium. In samples made in grade IV titanium, this difference was less evident, and even in the sample manufactured with grade IV and SLA treatment, the application of the nanometric modification of the surface made the surface optically less active. Regarding cell growth, all the surfaces studied, grouped in relation to the presence or not of the nanometric treatment, showed similar growth. Conclusions. Treatment of titanium oxide surfaces with ultraviolet irradiation made them change temporarily into superhydrophilic ones, which confirms that their biocompatibility could be improved in this way, or at least be maintained.

Thermal treatment to increase titanium wettability induces selective proteins adsorption from blood serum thus affecting osteoblasts adhesion

OBJECTIVES

To investigate how a thermal treatment to increase titanium wettability influences proteins adsorption from blood serum and osteoblasts responses.

METHODS

Titanium discs with machined or micro-rough profiles were thermally treated to obtain hydrophilic surfaces. The adsorption kinetics of two representative serum proteins were determined by Bradford assay, while the stable protein adsorption pattern from blood serum was investigated by SDS-PAGE and Western Blot analysis. Subsequently, MC3T3-E1 cells were cultured on titanium for 24h and assayed for adhesion and morphology.

RESULTS

Thermally-induced hydrophilicity dramatically improved the capacity of titanium to selectively adsorb fibronectin and fibrinogen from blood serum, without evident influence on other representative serum proteins. The selective adsorption of fibronectin was linked to the improved capacity of MC3T3-E1 cells to adhere and spread on hydrophilic surfaces.

SIGNIFICANCE

We identified a potential method to improve selective protein adsorption on titanium by enhancing implant surface wettability through a thermal treatment. Selective fibronectin adsorption was further indicated as the responsible for improved osteoblasts adhesion. Targeting specific cell response by selective protein adsorption appears to be crucial to conceive even more performant therapies.

A Histological Study of Vasoconstriction by Local Anesthetics in Mandible

To assess the effect of epinephrine-containing local anesthetics on vasoconstriction, we immunohistochemically measured the intravascular lumen area in different regions of the mandible. Twelve male Wistar rats were used. General anesthesia was induced and maintained with sevoflurane. Infiltration anesthesia was performed with 0.2 mL of epinephrine-free 2% lidocaine (E-) near the left mandibular first molar and with 0.2 mL of epinephrine-containing 2% lidocaine (E+) near the right mandibular first molar. After decalcification, the specimens were paraffinized, and thin sections were prepared and immunohistologically stained with an antismooth muscle actin antibody. The intravascular lumen area was measured in the mucosa, periodontal membrane, Haversian/Volkmann's canal, and bone marrow. A Mann-Whitney U test was used for statistical processing, and p < .05 was considered to indicate a statistically significant difference. In the oral mucosa and the periodontal membrane, E+ had a significantly smaller vascular lumen area than E-. In the Haversian/Volkmann's canal and the bone marrow, no significant intergroup difference was observed in the intravascular lumen area. We postulate that this is due to a low smooth muscle content of blood vessels in the mandible and suggest that the vasoconstrictive effect of epinephrine-containing local anesthetics within the mandible is ineffective.

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.

Bioactive Coating on Titanium Dental Implants for Improved Anticorrosion Protection: A Combined Experimental and Theoretical Study

In recent years, extensive studies have been continuously undertaken on the design of bioactive and biomimetic dental implant surfaces due to the need for improvement of the implant–bone interface properties. In this paper, the titanium dental implant surface was modified by bioactive vitamin D3 molecules by a self-assembly process in order to form an improved anticorrosion coating. Surface characterization of the modified implant was performed by field emission scanning electron microscopy (FE-SEM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and contact angle measurements (CA). The implant’s electrochemical stability during exposure to an artificial saliva solution was monitored in situ by electrochemical impedance spectroscopy (EIS). The experimental results obtained were corroborated by means of quantum chemical calculations at the density functional theory level (DFT). The formation mechanism of the coating onto the titanium implant surface was proposed. During a prolonged immersion period, the bioactive coating effectively prevented a corrosive attack on the underlying titanium (polarization resistance in order of 107 Ω cm2) with ~95% protection effectiveness.

Forces Causing One-Millimeter Displacement of Bone Fragments of Condylar Base Fractures of the Mandible after Fixation by All Available Plate Designs

Background: There has been no direct comparison of all existing plates dedicated for fracture osteosynthesis of mandibular condyle base until now. The aim of the study was to test mechanically all available designs of titanium plates on the market on polyurethane mandibles using an individually designed clamping system. Methods: Forces required for a 1 mm displacement of fixed fracture and incidents of screw loosening were recorded. Results indicated the best mechanical plates among all existing designs available. Results: It has occured that some of osseofixation plates should not be used any more, whereas some shape of the single plates are similar shape to two single plates shape are regarded as the best osseofixation method for condyle base fracture. Conclusion: General observation is the bigger plate and more screws, the better rigid stable osteosynthesis of mandibular condyle base. 4 plates of current designs of total 30 tested series can be recommended for open rigid internal fixation of fractures of the base of the mandibular condyle. The rest of 26 existing plates should not be used in condylar base fractures.

Photo-activated implants: a triple-blinded, split-mouth, randomized controlled clinical trial on the resistance to removal torque at various healing intervals

OBJECTIVES

Hydrophilic implant surfaces promote faster osseointegration of dental implants with a higher bone-implant contact (BIC) rate. Animal and in vitro studies proved that ultraviolet (UV) irradiation of titanium implants regains hydrophilicity. Clinical impact is still unclear. The objective of this RCT was to assess the removal torque (RT) required to unfix a surface-treated implant (test group) versus the original surface implant (control group) performed at various points in time. The null hypothesis stated that test and control implants will show the same deliberation force at specific time points.

MATERIAL AND METHODS

One hundred eighty partially edentulous patients were randomly assigned to six groups. In single-stage surgery, each patient received one test and one control implant. In total, 180 test and 180 control implants were placed epicrestally. Test implants received a surface treatment with UV irradiation prior to insertion, in order to reduce carbon and enhance hydrophilicity and thus wettability. Maximum RT values for test and control implants were recorded with a torque measuring device at implant placement (T1), after 1 (group 1), 2 (group 2), 3 (group 3), 4 (group 4), 6 (group 5) (T2), and 8 weeks (group 6) of healing. Subsequently, implants were returned to their original position for the continuation of the healing process.

RESULTS

No implant was lost. Age, gender, smoking, implant position, and bone quality could be excluded as confounding factors because of the lack of statistical significance. At T2, RT values were higher for test implants compared with those for control implants, being statistically significant in groups 2, 3, 4, and 6 (p < 0.05).

CONCLUSIONS

Our data support rejection of the null hypothesis.

CLINICAL RELEVANCE

Photo-activation of the surface of titanium implants leads to higher resistance to RT forces compared with that of non-treated implants, indicating improved healing and implant stability especially in the early healing phase.

Biocompatibility of (Ba,Ca)(Zr,Ti)O3 piezoelectric ceramics for bone replacement materials

Total joint replacement implants are generally designed to physically mimic the biological environment to ensure compatibility with the host tissue. However, implant instability exposes patients to long recovery periods, high risk for revision surgeries, and high expenses. Introducing electrical stimulation to the implant site to accelerate healing is promising, but the cumbersome nature of wired devices is detrimental to the implant design. We propose a novel strategy to stimulate cells at the implant site by utilizing piezoelectric ceramics as electrical stimulation sources. The inherent ability of these materials to form electric surface potentials under mechanical load allows them to act as internal power sources. This characteristic is commonly exploited in non-biomedical applications such as transducers or sensors. We investigate calcium/zirconium-doped barium titanate (BCZT) ceramics in an in vitro environment to determine their potential as implant materials. BCZT exhibits low cytotoxicity with human osteoblast and endothelial cells as well as high piezoelectric responses. Microstructural adaptation was identified as a route for optimizing piezoelectric behavior. Our results show that BCZT is a promising system for biomedical applications. Its characteristic ability to autonomously generate electric surface potentials opens the possibility to functionalize existing bone replacement implant designs to improve implant ingrowth and long-term stability.

Does preservation of the socket decrease marginal bone loss in the mandible after extraction of first molars?

The quality of the bone plays an important part in marginal bone loss (MBL) around dental implants. The aim of this study was to compare MBL around implants the sockets of which had been preserved with the bone around healed sites in the mandible after extraction of first molars. It was a prospective, cohort study in which subjects were divided into three groups (n=30 in each): dental implants were placed six months after preservation of the socket in the first group, eight weeks after tooth extraction in the second, and six months after tooth extraction in the third. The changes between the marginal bone level after loading of the implant and 12, 24, and 36 months later were considered to be the MBL. Age and sex were the variables studied, the condition of the bone (healed socket or preservation) was a predictive factor, and MBL was the outcome. Analysis of variance was used to compare MBL and age among groups. There were no differences in the mean MBL among the three groups 12, 24, and 36 months after loading (p=0.55, p=0.22, p=0.38, respectively). Preservation of the socket did not seem to affect MBL of the first molar of the mandible.

New Implant Macrogeometry to Improve and Accelerate the Osseointegration: An In Vivo Experimental Study

A new implant design with healing chambers in the threads was analyzed and compared with a conventional implant macrogeometry, both implants models with and without surface treatment. Eighty conical implants were prepared using commercially pure titanium (grade IV) by the company Implacil De Bortoli (São Paulo, Brazil). Four groups were performed, as described below: Group 1 (G1), traditional conical implants with surface treatment; group 2 (G2), traditional conical implants without surface treatment (machined surface); group 3 (G3), new conical implant design with surface treatment; group 4 (G4), new conical implant design without surface treatment. The implants were placed in the two tibias (n = 2 implants per tibia) of twenty New Zealand rabbits determined by randomization. The animals were euthanized after 15 days (Time 1) and 30 days (Time 2). The parameters evaluated were the implant stability quotient (ISQ), removal torque values (RTv), and histomorphometric evaluation to determine the bone to implant contact (%BIC) and bone area fraction occupancy (BAFO%). The results showed that the implants with the macrogeometry modified with healing chambers in the threads produced a significant enhancement in the osseointegration, accelerating this process. The statistical analyses of ISQ and RTv showed a significative statistical difference between the groups in both time periods of evaluation (p ≤ 0.0001). Moreover, an important increase in the histological parameters were found for groups G3 and G4, with significant statistical differences to the BIC% (in the Time 1 p = 0.0406 and in the Time 2 p < 0.0001) and the BAFO% ((in the Time 1 p = 0.0002 and in the Time 2 p = 0.0045). In conclusion, the result data showed that the implants with the new macrogeometry, presenting the healing chambers in the threads, produced a significant enhancement in the osseointegration, accelerating the process.

Nano-scale modification of titanium implant surfaces to enhance osseointegration

The main aim of this review study was to report the state of art on the nano-scale technological advancements of titanium implant surfaces to enhance the osseointegration process. Several methods of surface modification are chronologically described bridging ordinary methods (e.g. grit blasting and etching) and advanced physicochemical approaches such as 3D-laser texturing and biomimetic modification. Functionalization procedures by using proteins, peptides, and bioactive ceramics have provided an enhancement in wettability and bioactivity of implant surfaces. Furthermore, recent findings have revealed a combined beneficial effect of micro- and nano-scale modification and biomimetic functionalization of titanium surfaces. However, some technological developments of implant surfaces are not commercially available yet due to costs and a lack of clinical validation for such recent surfaces. Further in vitro and in vivo studies are required to endorse the use of enhanced biomimetic implant surfaces. STATEMENT OF SIGNIFICANCE: Grit-blasting followed by acid-etching is currently used for titanium implant modifications, although recent technological biomimetic physicochemical methods have revealed enhanced osteoconductive and anti-microbial outcomes. An improvement in wettability and bioactivity of titanium implant surfaces has been accomplished by combining micro and nano-scale modification and functionalization with protein, peptides, and bioactive compounds. Such morphological and chemical modification of the titanium surfaces induce the migration and differentiation of osteogenic cells followed by an enhancement of the mineral matrix formation that accelerate the osseointegration process. Additionally, the incorporation of bioactive molecules into the nanostructured surfaces is a promising strategy to avoid early and late implant failures induced by the biofilm accumulation.

A Study of Laser Micromachining of PM Processed Ti Compact for Dental Implants Applications

The paper deals with the experimental study of laser beam micromachining of the powder metallurgy processed Ti compacts applying the industrial grade fibre nanosecond laser operating at the wavelength of 1064 nm. The influence of the laser energy density on the surface roughness, surface morphology and surface elements composition was investigated and evaluated by means of surface roughness measurement, scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. The different laser treatment parameters resulted in the surfaces of very different characteristics of the newly developed biocompatible material prepared by advanced low temperature technology of hydride dehydride (HDH) titanium powder compactation. The results indicate that the laser pulse energy has remarkable effects on the machined surface characteristics which are discussed from the point of view of application in dental implantology.

Differential Healing Patterns of Mucosal Seal on Zirconia and Titanium Implant

Zirconia implants have become an alternative to titanium implants due to several advantages. The zirconia implant is relatively esthetic and highly resistant to bacteria. While biomaterial studies for zirconia implants have considerably accumulated, in vivo studies have not yet progressed. In the present study, the functional and biological properties of zirconia implants were analyzed thorough in vitro and in vivo studies. The proliferation properties of periodontal cells on the discs of machined surface titanium, hydroxyapatite coated titanium and zirconia were analyzed, and zirconia was shown to be favorable. In addition, small implant fixtures that can be applied to the jawbone of mice were manufactured and transplanted to C57BL/6 mice. The adhesion molecules expression patterns in peri-implant mucosa suggest a stronger mucosal seal and more adequate prevention of peri-implant epithelium (PIE) elongation in the zirconia implant when compared with other conventional materials. Differential laminin-332 expression in peri-implant mucosa of zirconia implants seems to regulate the PIE elongation. In conclusion, zirconia was found to be promising and advantageous with regards to the mucosal seal. And biological width (BW) of peri-implant mucosa is more desirable in zirconia implants compared to conventional titanium implants.

The Influence of Type 2 Diabetes Mellitus on the Osseointegration of Titanium Implants With Different Surface Modifications-A Histomorphometric Study in High-Fat Diet/Low-Dose Streptozotocin-Treated Rats

OBJECTIVES

Type 2 diabetes mellitus (T2DM) is a systemic disease that also compromises the bone healing capacity. In healthy individuals, surface modifications of dental implants are proven to increase bone response and implant success. The aim of this study was to clarify if the surface modifications also improve osseointegration in a setting with diabetes mellitus.

METHODS

T2DM was induced in 7 rats by a high-fat diet/low-dose streptozotocin injection. All animals received a hydroxyapatite (HA) implant, a sandblasted and acid-etched (SLA) implant, and a standard machined titanium implant for control in the tibia. After 4 weeks, thin-ground sections were produced, and the volume of new bone formation (nBV/TV) and bone-to-implant contact (nB.I/Im.I) were histomorphometrically analyzed.

RESULTS

Both surface modifications led to an increase of osseointegration compared with the machined surface implant in rats with T2DM. nBV/TV was highest in the SLA implants, whereas nB.I/Im.I was highest in the HA group. Regardless of the surface modification, a superordinate regional pattern of new bone formation over the length of the implant was observed.

CONCLUSIONS

Implants with HA coating and SLA surface modifications seem to have the potential to increase osseointegration also in T2DM rats when compared with a conventional machined surface.

Do the New Hydrophilic Surface Have Any Influence on Early Success Rate and Implant Stability during Osseointegration Period? Four-Month Preliminary Results from a Split-Mouth, Randomized Controlled Trial

OBJECTIVE

The objective of this study is to compare the implant stability of Hiossen ET III implants with its new hydrophilic (NH) surface and Hiossen ET III implants with the sandblasted and acid-etched (SA) surface.

MATERIALS AND METHODS

Patients required at least two teeth to be rehabilitated with a fixed, implant-supported restoration, consecutively enrolled. Patients randomly received SA surface implants (SA group) or SA implants with a newly developed bioabsorbable apatite nanocoating (NH group). Outcome measures were implant and prosthetic survival rate, complications, insertion torque, and implant stability quotient (ISQ) measured at implant placement and every week up to 8 weeks after implant placement. Comparison between groups was made by unpaired t-test, while the comparison between each follow-up will be made by paired t-tests to detect any change during the follow-up. Complications and failures were compared using Fisher's exact test.

RESULTS

A total of 14 patients were treated with 28 implants (14 SA and 14 NH). No implant and prosthesis failed 4 months after implant placement. No complications were experienced. At the 2nd week after implants placement, two implants in the SA group showed discontinuous measurements versus none in the NH group (p = 0.4815). Implants unscrewed during ISQ measurements and were rescrewed. Data recording stopped for 6 weeks. Both implants osseointegrated without any further complication. The NH implants did not show physiological ISQ decrease between 2nd and 4th week after implant placement, showing a more even pattern of ISQ values compared with SA implants (77.1 ± 4.6 vs. 72.9 ± 11.5; difference: 4.2 ± 12.1; p = 0.258). High ISQ values were found in both groups at each time point.

CONCLUSIONS

NH implants are a viable alternative to SA surface, as they seem to avoid the ISQ drop during the remodeling phase.

Al2O3 Particles on Titanium Dental Implant Systems following Sandblasting and Acid-Etching Process

Dental implants with moderately rough surfaces show enhanced osseointegration and faster bone healing compared with machined surfaces. The sandblasting and acid-etching (SA) process is one technique to create moderately rough dental implant surfaces. The purpose of this study was to analyse different commercially available implant systems with a SA-modified surface and to explore the widespread notion that they have similar surface properties regarding morphology and cleanliness. SA-modified surfaces of nine implant systems manufactured by Alpha-Bio Tec Ltd, Camlog Biotechnologies AG, Dentsply Sirona Dental GmbH, Neoss Ltd, Osstem Implant Co. Ltd, Institute Straumann AG, and Thommen Medical AG were analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) and examined for surface cleanliness. Six implants from three different lots were selected per each implant system. Mean particle counts for each implant and the mean size of the particles were calculated from three different regions of interest and compared using ANOVA and Tukey's test. SEM analysis showed presence of particles on the majority of analyzed implant surfaces, and EDX evaluations determined that the particles were made of Al₂O₃ and thus remnants of the blasting process. SPI®ELEMENT INICELL® and Bone Level (BL) Roxolid® SLActive® implant surfaces showed the highest mean particle counts, 46.6 and 50.3 per area, respectively. The surface of BL Roxolid® SLActive® implant also showed the highest variations in the particle counts, even in samples from the same lot. The mean size of particles was 1120±1011 μm², measured for USIII CA Fixture implants, while the biggest particle was 5900 μm² found on a BL Roxolid® SLActive® implant. These results suggest that not all manufacturers are able to produce implant surfaces without particle contamination and highlight that the surface modification process with the SA technique should be appropriately designed and controlled to achieve a clean and consistent final medical device.

Impact of Different Titanium Implant Thread Designs on Bone Healing: A Biomechanical and Histometric Study with an Animal Model

Threads of dental implants with healing chamber configurations have become a target to improve osseointegration. This biomechanical and histometric study aimed to evaluate the influence of implant healing chamber configurations on the torque removal value (RTv), percentage of bone-to-implant contact (BIC%), bone fraction occupancy inside the thread area (BAFO%), and bone and osteocyte density (Ost) in the rabbit tibia after two months of healing. Titanium implants with three different thread configurations were evaluated: Group 1 (G1), with a conventional “v” thread-shaped implant design; Group 2 (G2), with square threads; and Group 3 (G3), the experimental group with longer threads (healing chamber). Ten rabbits (4.5 ± 0.5 kg) received three implants in each tibia (one per group), distributed in a randomized manner. After a period of two months, the tibia blocks (implants and the surrounding tissue) were removed and processed for ground sectioning to evaluate BIC%, BAFO%, and osteocyte density. The ANOVA one-way statistical test was used followed by the Bonferoni’s multiple comparison test to determine individual difference among groups, considering a statistical difference when p < 0.05. Histometric evaluation showed a higher BAFO% values and Ost density for G3 in comparison with the other two groups (G1 and G2), with p < 0.05. However, the RTv and BIC% parameters were not significantly different between groups (p > 0.05). The histological data suggest that the healing chambers in the implant macrogeometry can improve the bone reaction in comparison with the conventional thread design.

Functionalization of Ceramic Coatings for Enhancing Integration in Osteoporotic Bone: A Systematic Review

Background: The success of reconstructive orthopaedic surgery strongly depends on the mechanical and biological integration between the prosthesis and the host bone tissue. Progressive population ageing with increased frequency of altered bone metabolism conditions requires new strategies for ensuring an early implant fixation and long-term stability. Ceramic materials and ceramic-based coatings, owing to the release of calcium phosphate and to the precipitation of a biological apatite at the bone-implant interface, are able to promote a strong bonding between the host bone and the implant. Methods: The aim of the present systematic review is the analysis of the existing literature on the functionalization strategies for improving the implant osteointegration in osteoporotic bone and their relative translation into the clinical practice. The review process, conducted on two electronic databases, identified 47 eligible preclinical studies and 5 clinical trials. Results: Preclinical data analysis showed that functionalization with both organic and inorganic molecules usually improves osseointegration in the osteoporotic condition, assessed mainly in rodent models. Clinical studies, mainly retrospective, have tested no functionalization strategies. Registered trademarks materials have been investigated and there is lack of information about the micro- or nano- topography of ceramics. Conclusions: Ceramic materials/coatings functionalization obtained promising results in improving implant osseointegration even in osteoporotic conditions but preclinical evidence has not been fully translated to clinical applications.

Sandblasting reduces dental implant failure rate but not marginal bone level loss: A systematic review and meta-analysis

Introduction

Sandblasting is one of the oldest implant surface modifications to enhance osseointegration. Regarding its superiority over machined surface controversies still exist. Our objective was to compare implant failures (IF) and marginal bone level (MBL) changes between sandblasted and machined dental implants by a meta-analysis utilizing the available data. The PROSPERO registration number of the meta-analysis is CRD42018084190.

Methods

The systematic search was performed in Cochrane, Embase and Pubmed. Inclusion criteria included participants with neither systemic diseases, nor excessive alcohol consumption, nor heavy smoking. We calculated pooled Risk Ratio (RRs) with confidence intervals of 95% (CIs) for dichotomous outcomes (implant failure) and weighted mean difference (WMD) CIs of 95% for continuous outcomes (marginal bone level change). We applied the random effect model with DerSimonian-Laird estimation. I² and chi² tests were used to quantify statistical heterogeneity and gain probability-values, respectively.

Results

Literature search revealed 130 records without duplicates. Out of these, seven studies met the inclusion criteria and all were included in data synthesis, involving 362 sand-blasted and 360 machined implants. The results indicate that there is an 80% (RR = 0.2 95% CI:0.06–0.67; I² = 0.0% p = 0.986) lower among sandblasted compared to machined implants after one year of use and 74% (RR = 0.26 95% CI:0.09–0.74; I² = 0.0% p = 0.968) five years of use, respectively. In contrast, there is no significant difference in MBL (WMD:-0.10mm, 95% CI:-0.20, 0.01; p>0.05; I² = 0.0%, p = 0.560 and WMD:-0.01mm, 95% CI:-0.12, 0.09; p>0.05; I² = 26.2%, p = 0.258) between the two implant surfaces after one and five years of use.

Conclusions

This meta-analysis reveals that sandblasting is superior over machined surface in implant failure but not in marginal bone level in healthy subjects. It also points out the need for further randomized clinical trials with large sample size for objective determination of the clinical benefits of certain implant surface modifications.

Cigarette Smoke Extract Exposure: Effects on the Interactions between Titanium Surface and Osteoblasts

The aim of this study was to explore the changes in the characteristics of titanium surface and the osteoblast-titanium interactions under cigarette smoke extract (CSE) exposure. In this study, CSE was used to simulate the oral liquid environment around the implant under cigarette smoke exposure. Titanium samples were immersed in CSE to explore the changes in the characteristics of titanium surface. The physical properties of titanium surface were measured, including surface micromorphology, surface elemental composition, roughness, and surface hydrophilicity. MC3T3-E1 cells were cultured on the titanium surface in vitro under different concentrations of CSE exposure, and cell adhesion, cell proliferation, and osteogenic differentiation were observed. The surface micromorphology and elemental composition of titanium surface changed under CSE exposure. No obvious changes were found in the surface roughness and the hydrophilicity of titanium samples. Moreover, the results of in vitro study showed that CSE exposure downregulated the cell spreading, proliferation, and osteogenic differentiation of MC3T3-E1 cells on the titanium surface. It could be speculated that some carbon-containing compounds from CSE adsorbed on the titanium surface and the osteoblast-titanium interactions were influenced under CSE exposure. It is hoped that these results could provide valuable information for further studies on smoking-mediated inhibition of implants osseointegration.

Physicochemical and in-vitro biological analysis of bio-functionalized titanium samples in a protein-rich medium

The long-term survivability of the implants is strongly influenced by the osseointegration aspects of the metal-bone interface. In this study, biological materials such as fibrinogen and fibrin are used to functionalize titanium surfaces to enhance the ability of implants to interact with human tissues for accelerated osseointegration. The biofunctionalized samples that were assessed by White Light Microscope, Scanning Electron Microscope and Water Contact Angle for surface properties proved samples etched with HF/HNO₃ to be better than HCl/H₂SO₄ in terms of having optimum roughness and hydrophilicity for our further experiments. To further investigate the in vitro osseointegration of the biofunctionalized samples, Osteoblasts were cultured on the surfaces to assess cell proliferation, adhesion, gene expression as well as the mineralization process. Further bacterial adhesion (Enterococcus faecalis) and electrochemical evaluation of surface coating stability were carried out. Results of the study show that the biofunctionalized surfaces provided high cell proliferation, adherence, gene expression, and mineralization compared to other control surfaces hence proving them to have efficient and enhanced osseointegration. Also, bacterial adhesion studies show that there is no augmented growth of bacteria on the biofunctionalized samples in comparison to control surfaces. Electrochemical studies proved the existence of a stable protein layer on the bio functionalized surfaces. Such a method can reduce the time for osseointegration that can decrease risks in early failures of implants due to its enhanced hydrophilicity and cytocompatibility.

What is the Best Micro and Macro Dental Implant Topography?

Implant surface micro and macro topography plays a key role in early osseointegration. The physicochemical features of the implant surface (ie, chemical composition, hydrophobicity/hydrophilicity and roughness) influence the deposition of extracellular matrix proteins, the precipitation of bone mineral, and the stimulation of cells. Modification of the implant topography provides better primary stability and faster osseointegration, allowing for immediate placement or immediate loading. Randomized clinical trials are warranted to compare the response of osseointegration with various implant micro and macro surface topographies in people with various local or systemic risk factors.

Micro/nano-hierarchical structured TiO2 coating on titanium by micro-arc oxidation enhances osteoblast adhesion and differentiation

Nano-structured and micro/nano-hierarchical structured TiO2 coatings were produced on polished titanium by the micro-arc oxidation (MAO) technique. This study was conducted to screen a suitable structured TiO2 coating for osteoblast adhesion and differentiation in dental implants. The formulation was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and wettability testing. Adhesion, proliferation and osteogenic differentiation of MG63 cells were analysed by SEM, Cell Counting Kit-8 (CCK-8) and quantitative real-time PCR. The micro/nano-hierarchical structured TiO2 coating with both slots and pores showed the best morphology and wettability. XRD analysis revealed that rutile predominated along with a minor amount of anatase in both TiO2 coatings. Adhesion and extension of MG63 cells on the micro/nano-hierarchical structured TiO2 coating were the most favourable. MG63 cells showed higher growth rates on the micro/nano-hierarchical structured TiO2 coating at 1 and 3 days. Osteogenic-related gene expression was markedly increased in the micro/nano-hierarchical structured TiO2 coating group compared with the polished titanium group at 7, 14 and 21 days. These results revealed the micro/nano-hierarchical structured TiO2 coating as a promising surface modification and suitable biomaterial for use with dental implants.

Engineered titanium implants for localized drug delivery: recent advances and perspectives of Titania nanotubes arrays

INTRODUCTION

Therapeutics delivery to bones to treat skeletal diseases or prevent postsurgical infections is challenging due to complex and solid bone structure that limits blood supply and diffusion of therapeutics administered by systemic routes to reach effective concentration. Titanium (Ti) and their alloys are employed as mainstream implant materials in orthopedics and dentistry; having superior mechanical/biocompatibility properties which could provide an alternative solution to address this problem.

AREAS COVERED

This review presents an overview of recent development of Ti drug-releasing implants, with emphasis on nanoengineered Titania nanotubes (TNTs) structures, for solving key problems to improve implants osseointegration, overcome inflammation and infection together with providing localized drug delivery (LDD) for bone diseases including cancer. Critical analysis of the advantages/disadvantages of developed concepts is discussed, their drug loading/releasing performances and specific applications.

EXPERT OPINION

LDD to bones can address many disorders and postsurgical conditions such as inflammation, implants rejection and infection. To this end, TNTs-Ti implants represent a potential promise for the development of new generation of multifunctional implants with drug release functions. Even this concept is extensively explored recently, there is a strong need for more preclinical studies using animal models to confirm the long-term safety and stability of TNTs-Ti implants for real-life medical applications.

Simple and facile preparation of recombinant human bone morphogenetic protein-2 immobilized titanium implant via initiated chemical vapor deposition technique to promote osteogenesis for bone tissue engineering application

Over the past few decades, titanium (Ti) implants have been widely used to repair fractured bones. To promote osteogenesis, immobilization of osteoinductive agents, such as recombinant human bone morphogenic protein-2 (rhBMP2), onto the Ti surface is required. In this study, we prepared rhBMP2 immobilized on glycidyl methacrylate (GMA) deposited Ti surface through initiated chemical vapor deposition (iCVD) technique. After preparation, the bio-functionalized Ti surface was characterized by physicochemical analysis. For in vitro analysis, the developed Ti was evaluated by cell proliferation, alkaline phosphatase activity, calcium deposition, and real-time polymerase chain reaction to verify their osteogenic activity against human adipose-derived stem cells (hASCs). The GMA deposited Ti surface was found to effectively immobilize a large dose of rhBMP2 as compared to untreated Ti. Additionally, rhBMP2 immobilized on Ti showed significantly enhanced osteogenic differentiation and increased calcium deposition with nontoxic cell viability. These results clearly confirm that our strategy may provide a simple, solvent-free strategy to prepare an osteoinductive Ti surface for bone tissue engineering applications.

Effect of Different Surface Treatments on Titanium Dental Implant Micro-Morphology

Background: Titanium dental implants are today widely used with osseointegration mainly dependently on the implant surface properties. Different processing routes lead to different surface characteristics resulting, of course, in different in situ behaviors of the implants. Materials: The effect of different treatments, whether mechanical or chemical, on the surface morphology of titanium implants were investigated. To this aim, various experimental methods, including roughness analysis as well scanning electron microscope (SEM) observations, were applied. Results: The results showed that, in contrast to the mechanical treatments, the chemical ones gave rise to a more irregular surface. SEM observations suggested that where commercial pure titanium was used, the chemical treatments provided implant surfaces without contaminations. In contrast, sandblasted implants could cause potential risks of surface contamination because of the presence of blasting particles remnants. Conclusions: The examined implant surfaces showed different roughness levels in relation to the superficial treatment applied. The acid-etched surfaces were characterized by the presence of deeper valleys and higher peaks than the sandblasted surfaces. For this reason, acid-etched surfaces can be more easily damaged by the stress produced by the peri-implant bone during surgical implant placement.

Immediate placement of tapered implants with a moderately rough anodized surface and smooth collar in fresh extraction sockets: A retrospective analysis with 10-year follow-up

BACKGROUND

There is limited long-term data on hard- and soft-tissue outcomes of implants immediately placed in postextraction sockets with immediate or early loading.

PURPOSE

To evaluate the clinical outcomes of immediately placed anodized tapered implants in consecutive patients with at least 10 years of follow up.

MATERIALS AND METHODS

This retrospective analysis evaluated outcomes of 61 consecutive patients who received 89 tapered implants with an anodized implant body and machined collar. Implants were placed in fresh extraction sites and functionalized using an immediate- or early-loading protocol. Outcome measures included survival, marginal bone level change (ΔMBL), and papilla index.

RESULTS

The 10-year cumulative survival rate was 100%. ΔMBL at the 10-year follow up was -0.86 ± 2.10 mm. At 10 years, patients had mesial and distal papilla index scores of 2 or 3 for 95.9% and 87.8% of implants, respectively.

CONCLUSIONS

When used for immediate placement and immediate- or early-loading protocols, this implant produced excellent long-term hard- and soft-tissue outcomes.

Effects of ultraviolet treatment and alendronate immersion on osteoblast-like cells and human gingival fibroblasts cultured on titanium surfaces

In this study, we evaluated the effects of ultraviolet (UV) treatment and alendronate (ALN) immersion on the proliferation and differentiation of MG-63 osteoblast-like cells and human gingival fibroblasts (HGFs) cultured on titanium surfaces. MG-63 cells were used for sandblasted, large grit, and acid-etched (SLA) titanium surfaces, and HGFs were used for machined (MA) titanium surfaces. SLA and MA specimens were subdivided into four groups (n = 12) according to the combination of surface treatments (UV treatment and/or ALN immersion) applied. After culturing MG-63 cells and HGFs on titanium discs, cellular morphology, proliferation, and differentiation were evaluated. The results revealed that UV treatment of titanium surfaces did not alter the proliferation of MG-63 cells; however, HGF differentiation and adhesion were increased in response to UV treatment. In contrast, ALN immersion of titanium discs reduced MG-63 cell proliferation and changed HGFs into a more atrophic form. Simultaneous application of UV treatment and ALN immersion induced greater differentiation of MG-63 cells. Within the limitations of this cellular level study, simultaneous application of UV treatment and ALN immersion of titanium surfaces was shown to improve the osseointegration of titanium implants; in addition, UV treatment may be used to enhance mucosal sealing of titanium abutments.

In Vitro and In Vivo Evaluation of Titanium Surface Modification for Biological Aging by Electrolytic Reducing Ionic Water

In this study, using electrolytic reducing ionic water (S-100®), a novel surface treatment method safely and easily modifying the surface properties was evaluated in vitro and in vivo. Ti-6Al-4V disks were washed and the disks were kept standing on a clean bench for one and four weeks for aging. These disks were immersed in S-100® (S-100 group), immersed in ultra-pure water (Control group), or irradiated with ultraviolet light (UV group), and surface analysis, cell experiment, and animal experiment were performed using these disks. The titanium surface became hydrophilic in the S-100 group and the amount of protein adsorption and cell adhesion rate were improved in vitro. In vivo, new bone formation was noted around the disk. These findings suggested that surface treatment with S-100® adds bioactivity to the biologically aged titanium surface. We are planning to further investigate it and accumulate evidence for clinical application.

Bioactive Titanium Surfaces: Interactions of Eukaryotic and Prokaryotic Cells of Nano Devices Applied to Dental Practice

Background: In recent years, many advances have been made in the fields of bioengineering and biotechnology. Many methods have been proposed for the in vitro study of anatomical structures and alloplastic structures. Many steps forward have been made in the field of prosthetics and grafts and one of the most debated problems lies in the biomimetics and biocompatibility of the materials used. The contact surfaces between alloplastic material and fabric are under study, and this has meant that the surfaces were significantly improved. To ensure a good contact surface with the cells of our body and be able to respond to an attack by a biofilm or prevent the formation, this is the true gold standard. In the dental field, the study of the surfaces of contact with the bone tissue of the implants is the most debated, starting from the first concepts of osteointegration. Method: The study searched MEDLINE databases from January 2008 to November 2018. We considered all the studies that talk about nanosurface and the biological response of the latter, considering only avant-garde works in this field. Results: The ultimate aim of this study is to point out all the progress made in the field of bioengineering and biotechnologies about nanosurface. Surface studies allow you to have alloplastic materials that integrate better with our body and allow more predictable rehabilitations. Particularly in the field of dental implantology the study of surfaces has allowed us to make huge steps forward in times of rehabilitation. Overcoming this obstacle linked to the time of osseointegration, however, today the real problem seems to be linked to the “pathologies of these surfaces”, or the possible infiltration, and formation of a biofilm, difficult to eliminate, being the implant surface, inert. Conclusions: The results of the present investigation demonstrated how nanotechnologies contribute substantially to the development of new materials in the biomedical field, being able to perform a large number of tests on the surface to advance research. Thanks to 3D technology and to the reconstructions of both the anatomical structures and eventually the alloplastic structures used in rehabilitation it is possible to consider all the mechanical characteristics too. Recent published papers highlighted how the close interaction between cells and the biomaterial applied to the human body is the main objective in the final integration of the device placed to manage pathologies or for rehabilitation after a surgical tumor is removed.

Covalently-Linked Hyaluronan versus Acid Etched Titanium Dental Implants: A Crossover RCT in Humans

Biochemical modification of titanium surfaces (BMTiS) entails immobilization of biomolecules to implant surfaces in order to induce specific host responses. This crossover randomized clinical trial assesses clinical success and marginal bone resorption of dental implants bearing a surface molecular layer of covalently-linked hyaluronan in comparison with control implants up to 36 months after loading. Patients requiring bilateral implant rehabilitation received hyaluronan covered implants in one side of the mouth and traditional implants in the other side. Two months after the first surgery, a second surgery was undergone to uncover the screw and to place a healing abutment. After two weeks, the operator proceeded with prosthetic procedures. Implants were evaluated by periapical radiographs and the crestal bone level was recorded at mesial and distal sites—at baseline and up to 36 months. One hundred and six implants were positioned, 52 HY-coated, and 48 controls were followed up. No differences were observed in terms of insertion and stability, wound healing, implant success, and crestal bone resorption at any time considered. All interventions had an optimal healing, and no adverse events were recorded. This trial shows, for the first time, a successful use in humans of biochemical-modified implants in routine clinical practice and in healthy patients and tissues with satisfactory outcomes.

Topography enhances Runx2 expression in outgrowing cells from iPS cell-derived embryoid bodies

The effect of differing polystyrene substrate topographies on the osteogenic potential of the outgrowing cells (OGCs) formed from mouse-induced pluripotent stem (iPS) cells (miPSCs)-derived embryoid bodies (EBs) was investigated. Polystyrene substrates were sandblasted with 25, 50, and 150 μm aluminum oxide particles to obtain topographies with average Sa values of 0.6, 1.1, and 1.8 μm, respectively. 3D-SEM was used to evaluate substrate's topographies. Examination was done by scanning electron microscopy (SEM), by immunocytofluorescence (ICF) analysis for vinculin, Runx2 and collagen type I, and by quantitative RT-PCR (qRT-PCR) analysis for Runx2 and collagen type I. SEM and ICF analyses revealed that surface roughness caused cells elongation (2, 6, 8, 10 times for the NT, 0.6 μm, 1.1 μm, and 1.8 μm, respectively). Vinculin staining demonstrated how the Sa value affected cellular attachment to the substrate. FA points were randomly distributed on flat surfaces, but rough surfaces resulted in more concentrated FA points on the podia of the cells (11.7, 25.2, 26.7, 16.6 vinculin spots per 20 μm² for the NT, 0.6 μm, 1.1 μm, and 1.8 μm, respectively). qRT-PCR revealed that Runx2 expression was highest on day 16 on surfaces with Sa of 0.6 μm and 1.1 μm. Collagen type I expression increased from day 0 to day 16, no significance was found among the groups. In conclusion, surface topography affects cell shape and expression of early osteogenic potential in OGC, particularly surfaces with Sa values of 0.6 μm and 1.1 μm which showed the highest concentration of FA points on podia. These findings could be utilized in the development of inner surface topographies of scaffolds used with iPSCs. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2288-2296, 2019.

Histopathological Evaluation of Orthopedic Medical Devices: The State-of-the-art in Animal Models, Imaging, and Histomorphometry Techniques

Orthopedic medical devices are continuously evolving for the latest clinical indications in craniomaxillofacial, spine, trauma, joint arthroplasty, sports medicine, and soft tissue regeneration fields, with a variety of materials from new metallic alloys and ceramics to composite polymers, bioresorbables, or surface-treated implants. There is great need for qualified medical device pathologists to evaluate these next generation biomaterials, with improved biocompatibility and bioactivity for orthopedic applications, and a broad range of knowledge is required to stay abreast of this ever-changing field. Orthopedic implants require specialized imaging and processing techniques to fully evaluate the bone-implant interface, and the pathologist plays an important role in determining the proper combination of histologic processing and staining for quality slide production based on research and development trials and validation. Additionally, histomorphometry is an essential part of the analysis to quantify tissue integration and residual biomaterials. In this article, an overview of orthopedic implants and animal models, as well as pertinent insights for tissue collection, imaging, processing, and slide generation will be provided with a special focus on histopathology and histomorphometry evaluation.

Finite Element Analysis of Novel Separable Fixture for Easy Retrievement in Case with Peri-Implantitis

Peri-implantitis is a common complication following dental implant placement, which may lead to bone loss and fixation failure. With the conventional fixture, it is difficult to perfectly clear-up the infection. To solve this, we have designed a separable fixture of which the top part is replaceable. This study aimed to compare the structural and biomechanical stability of the separable and conventional fixture. A single surgical model corresponding to the first molar in a virtual mandible model and conventional/separable implants were reproduced to compare the biomechanical characteristics of the implants using finite element analysis (FEA). The loading condition was 200N preload in the first step, and 100N (Axial), 100N (15°), and 30N (45°) in the second step. The stress distribution on the cortical bone in the separable implant was lower than the conventional implant. In particular, the Peak von Mises Stress (PVMS) values of the separable implant under lateral load was found to be about twice as low as that of the conventional implant. In this study, we suggest that the separable implant has an equivalent biomechanical stability compared to the conventional implant, is easy to retrieve in the case of peri-implantitis, and has an excellent initial stability after the surgery when used in stage 2.

Factors Influencing Resonance Frequency Analysis (RFA) Measurements and 5-Year Survival of Neoss Dental Implants

BACKGROUND

Diagnostic instruments based on resonance frequency analysis (RFA) can be utilised to assess dental implant stability during treatment and follow-up.

AIM

The aim of the present study was to investigate the influence of patient- and implant-related factors on implant stability and the 5-year implant survival. In addition, the influence of stability (ISQ value) at placement and abutment connection on implant survival was evaluated.

MATERIALS AND METHODS

RFA measurements from a total of 334 consecutive patients with 745 dental implants (Neoss Ltd., Harrogate, UK) were retrospectively analysed after at least 5 years in function. Statistics were used to evaluate the influence of the different variables on implant stability and implant survival. Odds ratio calculations were performed to compare the risk for implant failure using 60, 65, 70, and 75 ISQ as threshold levels at placement and loading.

RESULTS

A total of 20 implant failures in 14 patients were noted during the 5 years of follow-up, giving an overall cumulative survival rate (CSR) of 97.3% at the implant level and 95.8% at the patient level. Gender, jaw, position, bone quality, and implant diameter had an influence on implant stability at placement. Jaw, bone quality, and implant diameter had an influence on stability after 3-4 months of healing. More failures were observed in full than in partial rehabilitations. Age, gender, jaw, position, bone quantity, bone quality, implant diameter, and implant length had no influence on implant survival. Implants with ISQ values below the threshold levels showed lower survival rates compared to implants with values above these levels.

CONCLUSIONS

The present study showed a significantly higher risk for implant failure, showing an ISQ value below 70 and 75 at placement or after 3-4 months of healing. The results indicate that RFA measurements can be used to identify implants with increased risk for failure.

Comparison of Osseointegration of Five Different Surfaced Titanium Implants

The topography, chemical features, surface charge, and hydrophilic nature of titanium implant surfaces are crucial factors for successful osseointegration. This study aimed to investigate the bone implant contact (BIC) ratio of titanium dental implants with different surface modification techniques using the rat femoral bone model. Sandblasted and acid washed (SL-AW), sandblasted (SL), resorbable blast material (RBM), microarc (MA), and sandblasted and microarc (SL-MA) surfaces were compared in this study. Forty male Sprague-Dawley rats were used in this study. The rats were divided into 5 equal groups (n = 8), and totally 40 implants were integrated into the right femoral bones of the rats. The rats were sacrificed 12 weeks after the surgical integration of the implants. The implant surface-bone tissue interaction was directly observed by a light microscope, and BIC ratios were measured after the nondecalcified histological procedures. Bone implant contact ratios were determined as follows: SL-AW: 59.26 ± 14.36%, SL: 66.01 ± 9.63%, RBM: 63.53 ± 11.23%, MA: 65.51 ± 10.3%, and SL-MA: 68.62 ± 6.6%. No statistically significant differences were found among the 5 different surfaced titanium implant groups (P > 0.05). Our results show that various implant surface modification techniques can provide favorable bone responses to the BIC of dental implants.

Astragaloside IV promotes the proliferation and migration of osteoblast-like cells through the hedgehog signaling pathway

The present study aimed to investigate the effects of astragaloside IV on osteoblast-like cell proliferation and migration, in addition to the underlying signaling pathway. In order to observe the effect on proliferation, a Cell Counting Kit-8 assay and flow cytometry were used. To detect cell migration ability, cell scratch and Transwell cell migration assays were performed. The RNA and protein expression levels of hedgehog signaling molecules, including Sonic hedgehog (SHH) and GLI family zinc finger 1 (GLI1), were examined by reverse transcription-quantitative polymerase chain reaction and western blot analyses. To inhibit the hedgehog signaling pathway, cyclopamine was used. Astragaloside IV, at a dosage of 1×10⁻²µg/ml in MG-63 cells and 1×10⁻³µg/ml in U-2OS cells, resulted in the enhanced proliferation and migration of cells, and the gene expression levels of the SHH and GLI1 were significantly increased. The combination of astragaloside IV and cyclopamine reduced MG-63 and U-2OS cell proliferation and migration, and inhibited the gene expression of SHH and GLI1. Astragaloside IV enhanced the proliferation and migration of human osteoblast-like cells through activating the hedgehog signaling pathway. The results of the present study provide a rational for the mechanistic link in astragaloside IV promoting the proliferation and migration of osteoblasts via the hedgehog signaling pathway.

Novel in vitro comparative model of osteogenic and inflammatory cell response to dental implants

OBJECTIVES

Roughened dental implants promote mesenchymal stem cell (MSCs) osteoblastic differentiation, and hydrophilic modifications induce anti-inflammatory macrophages activation. While the effect of different surface modifications on osseointegration of commercial dental implants have been compared in vivo and clinically, the initial cellular response to these modifications often overlooked. We aimed to characterize the macrophage inflammatory response and MSC osteogenesis across different commercially available implants in vitro.

METHODS

Six commercially available rough implants [OsseoSpeed™ (Astra-Tech™, Implant A); Osseotite^® (Biomet 3i™, Implant B); TiUnite™ (Nobel-Biocare^®, Implant C); Ti-SLA^®, (Implant D), Roxolid^® (RXD-SLA, Implant E), RXD-SLActive^® (Implant F) (Straumann^®)] were examined. Macrophages and MSCs were seeded directly on implants and cultured in custom vials. mRNA and protein levels of pro- (IL1B, IL6, IL17A, CXCL10, TNFa) and anti- (IL4, IL10, TGFB1) inflammatory markers were measured after 24 and 48h in macrophages. Osteoblastic differentiation of MSCs was assessed after seven days by alkaline phosphatase activity, osteocalcin, and angiogenic, osteogenic, and inflammatory markers by ELISA and qPCR (n=6/variable, ANOVA, post hoc Tukey HSD with α=0.05).

RESULTS

Hydrophilic implant F induced the highest level of osteogenic factor released from MSCs and anti-inflammatory factors from macrophages with the lowest level of pro-inflammatory factors. Alternatively, implants A and C supported lower levels of osteogenesis and increased secretion of pro-inflammatory factors.

SIGNIFICANCE

In this study, we successfully evaluated differences in cell response to commercially available clinical implants using an in vitro model. Data from this model suggest that not all surface modification procedures generate the same cell response.

Anodised or turned dental implants?

Data sourcesAn electronic search without time or language restrictions was undertaken using several databases: PubMed/Medline, Web of Science and the Cochrane Oral Health Group Trials Register and ongoing clinical trials. Manual searches were performed in dental implant related journals and reference lists of identified studies, and relevant reviews were scanned for possible additional studies.Study selectionEligibility criteria included human clinical studies, either randomised or not, comparing implant failure rates, MBL and/or post-operative infection in any group of patients receiving turned (machined) and anodised-surface (TiUnite) implants, both from the same implant manufacturer.Data extraction and synthesisThe titles and abstracts of all reports identified through the electronic searches were read independently by the three authors. For studies appearing to meet the inclusion criteria, or for which there were insufficient data in the title and abstract to make a clear decision, the full report was obtained. Disagreements were resolved by discussion between the authors. Quality assessment of the studies was executed according to the Newcastle-Ottawa scale (NOS), which is a quality assessment tool used when observational studies are also included in systematic reviews.ResultsThirty-eight publications were included. The results suggest a risk ratio =2.82(95%CI, 1.95 - 4.06, P < 0.00001) for failure of turned implants when compared to anodised-surface implants. Sensitivity analyses showed similar results when only the studies inserting implants in maxillae or mandibles were pooled. There were no statistically significant effects of turned implants on the MBL (mean difference [MD]=0.02, (95%CI, 0.16 - 0.20; P = 0 82) in comparison to anodised implants. The results of a meta-regression considering the follow-up period as a covariate suggested an increase of the MD with the increase in the follow-up time (MD increase 0.012 mm year 1), however, without a statistical significance (P = 0.813). Due to lack of satisfactory information, meta-analysis for the outcome 'post-operative infection' was not performed.ConclusionsWithin the limitations of the existing investigations, the present study suggests that turned implants have a statistically higher probability to fail than anodised-surface implants, regardless of whether the implants were placed in maxilla or mandible. There were no statistically significant effects of turned implants on the MBL when compared with anodised implants. A comparison of post-operative infection between the implant types was not possible, due to lack of sufficient information. The reliability and validity of the data collected, the limitations of the quality assessment tool and the potential for biases and confounding factors are some of the shortcomings of the present study. The results have to be interpreted with caution due to the presence of several confounding factors in the included studies.

MicroRNA-29a-3p enhances dental implant osseointegration of hyperlipidemic rats via suppressing dishevelled 2 and frizzled 4

Background

Fine osseointegration is the basis of long-term survival of implant. In our previous study, we observed a strong correlation between hyperlipidemia and compromised osseointegration. MicroRNA-29a-3p (miR-29a-3p) has been discovered to participate in bone marrow mesenchymal stem cells (BMSCs) differentiation. However, the role and the underlying mechanisms of hyperlipidemia and miR-29a-3p in osseointegration still remain obscure.

Results

In peri-implant bone tissues of hyperlipidemia rats, bone mass, mineralization and bone trabecula formation were weakened. Alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2), and miR-29a-3p expression were reduced. While in normal rats, implant-bone interfaces were filled with dense new bone and ALP, Runx2 and miR-29a-3p were up-regulated. Overexpressed miR-29a-3p can reverse the adverse effect of hyperlipidemia on osseointegration. Implants were tightly integrated with the surrounding dense new bone tissues, and ALP as well as Runx2 mRNAs were enhanced in miR-29a-3p overexpressed and hyperlipidemia rats, while little peri-implant bone tissue existed, ALP and Runx2 deregulated on miR-29a-3p inhibited rats. Dishevelled 2 (Dvl2) mRNA was declined in peri-implant bone tissue of high-fat (HF) group than normal group, while frizzled 4 (Fzd4) mRNA declined on day 5 and increased from day 10 to day 20 after implantation in hyperlipidemia rats than in normal rats. Next, BMSCs were cultured under HF or normal medium in vitro. In the HF group, ALP activity and mineralization, ALP and Runx2 mRNAs and proteins expression, and miR-29a-3p expression were suppressed, while adipogenesis was increased, as a result, cytoskeletons were sparse and disordered compared to control group. However, when miR-29a-3p was overexpressed in BMSCs, ALP activity, ALP, Runx2, Dvl2 and Fzd4 mRNAs and proteins expressions were up-regulated. As miR-29a-3p was inhibited in BMSCs, the reverse results were obtained. In addition, promoter assay revealed that miR-29a-3p can directly suppress Wnt/β-catenin pathway related Dvl2 and Fzd4 through binding to their 3'-UTR.

Conclusions

MiR-29a-3p facilitated implant osseointegration via targeting Wnt/β-catenin pathway-related Dvl2 and Fzd4. MiR-29a-3p/Dvl2/Fzd4 may serve as a promising therapeutic target for hyperlipidemia osseointegration.

Influence of Implant Neck Design on Peri-Implant Tissue Dimensions: A Comparative Study in Dogs

This in vivo study assessed (hard and soft) peri-implant tissue remodeling around implants with micro-ring and open-thread neck designs placed in a dog model. Twenty histological sections corresponding to four different implant designs that were placed in America Foxhound dogs were obtained from previous studies. All the implants had been placed under identical conditions and were divided into four groups: Group A, micro-rings on implant neck plus 0.5 mm refined surface; Group B, micro-rings on implant neck; Group C, open-thread neck; and, Group D, double-spiral neck. Eight weeks after surgery, the integrated implants were removed and processed for histological examination. Crestal bone loss and bone-to-implant contact was greater for micro-ring necks than open-thread necks. Soft tissues showed significant differences on both buccal and lingual aspects, so that the distance from peri-implant mucosa to the apical portion of the barrier epithelium was smaller in the micro-ring groups. So, in spite of generating greater bone-to-implant contact, implants with micro rings produced more bone loss than open-thread implants. Moreover, the outcomes that were obtained IPX implants smooth neck design produced less bone loss in the cervical area, following by Facility implants when compared with the other open thread and microthreaded implant designs. Implant thread design can influence on bone remodeling in the cervical area, related to bundle bone preservation.