Direct Bone Contact Research Articles

Evaluation of biocompatibility and osseointegration of multi-component TiAl6V4 titanium alloy implants.

This study aimed to investigate the biocompatibility and osseointegration of novel titanium (Ti) implants with a perforated part with high surface roughness (Ra >4 μm) and a smooth solid part (test group), as compared to smooth solid Ti implants (control group; Ra < 0.8 μm). Test and control implants were implanted in rabbit femurs. After 4 and 15 weeks, host tissue reaction and quality of tissue formed were evaluated with histopathology, while micro-CT scans were used to quantitatively assess bone-implant contact (BIC), surrounding bone formation, and bone ingrowth. After 4 and 15 weeks, minimal host reaction was found in the test group. Histopathological analysis showed new bone formation around the implants in both the test and control groups after 4 weeks. Furthermore, additional bone growth was often observed within the holes of the test implants. After 15 weeks, the test implants showed high bone ingrowth and the presence of mature bone in direct contact with the implant surface, whereas, bone ingrowth was poorer for the control group with 30% of the control implants, showing larger gaps at the bone-implant interface. Quantitative micro-CT analysis revealed comparable BIC and bone formation in both groups at 4 weeks, but higher BIC and more bone formation in the test group than in the control group after 15 weeks. No significant differences were observed in any of the analyses. In conclusion, partially perforated, high-roughness Ti implants showed excellent osseointegration and minimal host reaction, indicating their potential for orthopedic applications in bone repair and regeneration.

Comparative Analysis of Osseodensification and Standard Implant Site Preparation Techniques in Low Density Bone

Introduction. Dental implantation is getting more popular with patients who require total dental rehabilitation. Patients note that possibility of immediate loading based on dental implants is more favorable treatment option due to active social life. Low bone density, often occurred in the maxilla, frequently presents challenges for clinicians to achieve successful implant primary stability for predictable immediate loading.The aim of our study was to increase the efficiency of treatment of patients who require dental implantation in the maxilla.Materials and methods. Twenty-seven patients aged from 27 to 66 years with missing teeth in the alveolar process of maxilla were treated. All patients in this randomized clinical trial were divided into two groups. We used two methods for implant site preparation: the standard technique according to manufacturer’s recommendations in the first group (n = 13) and the Osseodensification technique via Densah drills (n = 14) in the second. All patients were treated by Astra Tech dental implants with the same dimensions (diameter 4 mm, length 9 mm). Immediately after implant placement the data of the frequency-resonance analysis of the implant stability and insertion torque were installed and obtained. Furthermore, a comparison of the operation time was carried out. Clinical evaluation and patient appreciation of pain, edema and hyperemia of the mucosa were evaluated using a questionnaire at 1, 3, 5 and 7 days after surgery. The measurement of the values of the stability quotient of the implants was repeated and carried out after six months.Results. Higher values of implant primary stability (insertion torque and implant stability quotient during surgery) were showed in the osseodensification group (IT — (45,0±5,8), ISQ — (71,8±2,9)) in comparison with standard technique (IT — (27,7±3,8), ISQ — (62,8±3,2)); p &lt; 0,05.Discussion. Osseodensification technique promotes compaction of a low density bone in direct contact with the implant, which leads to higher implant primary stability due to the physical interaction between bone and implant.Conclusion. The obtained results allow us to consider that the osseodensification method is progressive for improving the effectiveness of implantological treatment on maxilla.

SURFACE MATTERS THAN THE IMPLANT ITSELF-A REVIEW

Nowadays dental implants are a predictable and popular treatment option for tooth replacement in completely or partially edentulous patients. Implants are preferred over conventional treatment due to certain advantages it offers like preservation of bone; preservation of adjacent teeth, durability, better mastication and speech etc.Implant comes in direct bone contact and anchors through osseointegration. Successful osseointegration revolves around many factors such as biocompatibility of the implant material, quality and quantity of the available bone, surface treatment of the implant, loading and surgical protocol and various other systemic and local factors. Predictability of clinical success of dental implants can be enhanced by using newer materials or alterations in designs, surgical or loading protocols on the basis of available literature. Various studies have suggested that rough surface of implant enhances its integration with bone than a smooth implant surface. Several approaches are used to attain a rough surface and to improve the process of osseointegration of titanium dental implants. The present paper reviews different methods of treating implant surfaces to enhance bone implant interaction starting from the basic material used in dental implant manufacture.

In vitro and in vivo degradation behavior of Mg-0.45Zn-0.45Ca (ZX00) screws for orthopedic applications

Magnesium (Mg) alloys have become a potential material for orthopedic implants due to their unnecessary implant removal, biocompatibility, and mechanical integrity until fracture healing. This study examined the in vitro and in vivo degradation of an Mg fixation screw composed of Mg-0.45Zn-0.45Ca (ZX00, in wt.%). With ZX00 human-sized implants, in vitro immersion tests up to 28 days under physiological conditions, along with electrochemical measurements were performed for the first time. In addition, ZX00 screws were implanted in the diaphysis of sheep for 6, 12, and 24 weeks to assess the degradation and biocompatibility of the screws in vivo. Using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), micro-computed tomography (μCT), X-ray photoelectron spectroscopy (XPS), and histology, the surface and cross-sectional morphologies of the corrosion layers formed, as well as the bone-corrosion-layer-implant interfaces, were analyzed. Our findings from in vivo testing demonstrated that ZX00 alloy promotes bone healing and the formation of new bone in direct contact with the corrosion products. In addition, the same elemental composition of corrosion products was observed for in vitro and in vivo experiments; however, their elemental distribution and thicknesses differ depending on the implant location. Our findings suggest that the corrosion resistance was microstructure-dependent. The head zone was the least corrosion-resistant, indicating that the production procedure could impact the corrosion performance of the implant. In spite of this, the formation of new bone and no adverse effects on the surrounding tissues demonstrated that the ZX00 is a suitable Mg-based alloy for temporary bone implants.

Impact of bone-implant gap size on the interfacial osseointegration: an in vivo study

BackgroundThe bone-implant gap resulted from morphological mismatch between cervical bony endplates and implant footprint may have adverse impact on bone-implant interfacial osseointegration of cervical disc arthroplasty (CDA). The purpose of the study was to evaluate the impact of bone-implant gap size on the interfacial osseointegration in a rabbit animal model.MethodsA series of round-plate implants with different teeth depth (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm) was specifically designed. A total of 48 New Zealand white rabbits were randomly categorized into four groups by the implants they received (0.5 mm: group A, 1.0 mm: group B, 1.5 mm: group C, 2.0 mm: group D). At 4th and 12th week after surgery, animals were sacrificed. Micro-CT, acid fuchsin and methylene blue staining and hematoxylin and eosin (HE) staining were conducted.ResultsAt 4th week and 12th week after surgery, both micro-CT and HE staining showed more new bone formation and larger bone coverage in group A and group B than that in group C and group D. At 12th week, the bone biometric parameters were significantly superior in group C when compared with group D (p < 0.05). At 12th week, hard tissue slicing demonstrated larger portion of direct contact of new bone to the HA coating in group A and group B.ConclusionsBone-implant gap size larger than 1.0 mm negatively affected bone-implant osseointegration between compact bone and HA coated implant surface.

Coating Ti6Al4V implants with nanocrystalline diamond functionalized with BMP-7 promotes extracellular matrix mineralization in vitro and faster osseointegration in vivo

The present study investigates the effect of an oxidized nanocrystalline diamond (O-NCD) coating functionalized with bone morphogenetic protein 7 (BMP-7) on human osteoblast maturation and extracellular matrix mineralization in vitro and on new bone formation in vivo. The chemical structure and the morphology of the NCD coating and the adhesion, thickness and morphology of the superimposed BMP-7 layer have also been assessed. The material analysis proved synthesis of a conformal diamond coating with a fine nanostructured morphology on the Ti6Al4V samples. The homogeneous nanostructured layer of BMP-7 on the NCD coating created by a physisorption method was confirmed by AFM. The osteogenic maturation of hFOB 1.19 cells in vitro was only slightly enhanced by the O-NCD coating alone without any increase in the mineralization of the matrix. Functionalization of the coating with BMP-7 resulted in more pronounced cell osteogenic maturation and increased extracellular matrix mineralization. Similar results were obtained in vivo from micro-CT and histological analyses of rabbit distal femurs with screws implanted for 4 or 12 weeks. While the O-NCD-coated implants alone promoted greater thickness of newly-formed bone in direct contact with the implant surface than the bare material, a further increase was induced by BMP-7. It can be therefore concluded that O-NCD coating functionalized with BMP-7 is a promising surface modification of metallic bone implants in order to improve their osseointegration.

Bone healing around titanium implants in a preclinical model of bile duct ligation-induced liver injury.

ObjectivesChronic liver disease increases the risk for periodontal disease and osteoporotic fractures, but its impacts on bone regeneration remain unknown. Herein, we studied the impact of liver cirrhosis on peri‐implant bone formation.Material and MethodsA total of 20 male Wistar rats were randomly divided into two groups: one with the common bile duct ligated (BDL) and the respective sham‐treated control group (SHAM). After four weeks of disease induction, titanium mini‐screws were inserted into the tibia. Successful induction of liver cirrhosis was confirmed by the presence of clinical symptoms. Another four weeks later, peri‐implant bone volume per tissue volume (BV/TV) and bone‐to‐implant contact (BIC) were determined by histomorphometric analysis.ResultsPeri‐implant bone formation was not significantly different between the SHAM and BDL groups. In the cortical compartment, the median percentage of peri‐implant new bone was 10.1% (95% CI of mean 4.0–35.7) and 22.5% (13.8–30.6) in the SHAM and BDL groups, respectively (p = .26). Consistently, the new bone in direct contact with the implant was 18.1% (0.4–37.8) and 23.3% (9.2–32.8) in SHAM and BDL groups, respectively (p = .38). When measuring the medullary compartment, the new bone area was 7.1% (4.8–10.4) and 10.4% (7.2–13.5) in the SHAM and BDL groups, respectively (p = .17). Medullary new bone in direct contact with the implant was 10.0% (1.2–50.4) and 20.6% (16.8–35.3) in SHAM and BDL groups, respectively, and thus comparable between the two groups (p = .46).ConclusionsBile duct ligation has no significant impact on the early stages of peri‐implant bone formation.

Effects of the local administration of antibiotics on bone formation on implant surface in animal models: A systematic review and meta-analysis.

SummaryPurposeThis review aimed to evaluate the effects of the local delivery of antibiotics incorporated in implant surfaces on some quantitative parameters of bone formation.Materials and methodsAn electronic search was undertaken in three databases (PubMed, Scopus, Embase) in addition to hand searching. The search was limited to animal experiments using endosseous implants combined with localized antibiotics release. Meta-analyses were performed for the percentages of bone volume (BV) and bone-to-implant contact (BIC).ResultsNine studies met the inclusion criteria. Several methods were identified for local delivery of antibiotics at the bone-implant interface, but the most commonly used method was by coating (incorporating the implant surface with the antibiotic agents). Different antibiotic agents were used, namely bacitracin, doxycycline, enoxacin, gentamicin, minocycline, tobramycin, and vancomycin. There was no statistically significant difference in the percentage of BIC between implants with or without localized antibiotic release (P = 0.59). The meta-analysis revealed higher BV around implants coated with antibiotics compared to control groups (without antibiotics) (P < 0.01).ConclusionIt is suggested that the local administration of antibiotics around implants did not adversely affect the percentage of direct bone contact around implants, with a tendency for a slightly better bone formation around implants when combined with local administration of antibiotics. It is a matter of debate whether these in vivo results will have the same effect in the clinical setting. However, the risk of bias of these studies may, to some extent, question the validity of these results.

Technique for Medial Closing-Wedge Proximal Tibia Osteotomy in the Valgus Knee

Valgus malalignment can be corrected with a medial closing-wedge proximal tibia osteotomy in patients with symptomatic lateral compartment disease. Advantages of this technique include the inherent stability of the closing wedge with direct bone contact and reliable healing that enables early weight bearing and shorter recovery time. In addition, a tibial-based osteotomy alters joint contact forces in both flexion and extension versus femoral-based osteotomies. The purpose of this article is to present a reproducible technique for medial closing-wedge proximal tibia osteotomy and review the indications, preoperative planning, rationale, and clinical outcomes.

Dorsal minimally invasive plate osteosynthesis of the distal tibia with regard to adjacent anatomical characteristics

IntroductionThe aim of this study was to perform MIPO of the distal tibia from a dorsomedial and dorsolateral approach and to evaluate their feasibility and risk of injury to adjacent anatomical structures. Material & MethodsA total of 18 extremities from 9 adult human cadavers was included in the study. In each cadaver, one lower leg underwent application of a 12-hole 3.5 LCP metaphyseal plate from the medial and the further one from the lateral approach. For the medial approach, a 4 cm skin incision was performed at the tibial border of the Achilles tendon, starting from 1 cm proximal to its insertion point at the calcaneal tuberosity. Entrance was gained between the medial border of the flexor hallucis longus tendon and the medial neurovascular bundle. Regarding the lateral approach, the skin was incised over a length of about 4 cm at the lateral border of the Achilles tendon, approximately 1 cm proximal to its insertion point. Entrance was gained between the Achilles tendon and the peroneus brevis muscle. The plates were inserted in direct bone contact in a proximal direction and the proximal and distal ends were fixed. During dissection, the proximal and distal holes beneath the crossing points of the neurovascular bundle and the plate were noted. The distal and proximal intersection points of the neurovascular bundle and the plate were measured with reference to the distal border of the plate. ResultsConcerning the medial approach, the neurovascular bundle was on median located between the 6th and 11th plate holes starting from distal. The bundle intersected the plate distally at a mean height of 65.8 mm and proximally at 156.8 mm on average. For the lateral approach, the neurovascular bundle was situated between the 6th and the 12th plate hole from distal. It crossed the plate distally at a mean of 61.0 mm and proximal at a mean height of 153.9 mm. In none of the cases, lacerations of the neurovascular bundle were observed. ConclusionIn conclusion, MIPO from the dorsomedial and dorsolateral approach are both safe procedures as indicated by our study.

Successful Management of Peri-Implantitis around Short and Ultrashort Single-Crown Implants: A Case Series with a 3-Year Follow-Up.

Introduction and Aim In case of peri-implantitis, resective surgery is contraindicated for short and ultrashort implants, limiting the treatment options to regenerative surgery or to implant removal. This retrospective case series presents the clinical and radiographic outcomes of a surgical regenerative procedure to treat peri-implantitis around short and ultrashort implants. Materials and Methods The study is a retrospective evaluation of patients suffering from peri-implantitis and those who underwent access flap surgery, concomitant chemical and mechanical decontamination of implant surface, and bone grafting using a self-hardening mixture of bone substitutes and biphasic calcium sulfate. No membranes were applied to cover the grafting material, and primary tension-free closure was achieved. The retrospective protocol was reviewed and approved by the Ethics Committee for Clinical Sperimentation (CESC) of Verona and Rovigo, Italy (based in the University of Verona) (Prog. 1863CESC. Date of approval: 2018-07-04). Results 15 patients (17 implants) have been diagnosed with peri-implantitis after a mean follow-up of 24 months after loading. Implant length was between 5 and 8 mm. 8 patients (10 implants) had a history of periodontitis. At baseline, the mean PD (probing pocket dept) at the deepest site was 8.12 mm, with an average mBI (modified bleeding index) of 2.35 and a mean BD (bone defect depth) of 3.04 mm. At the 3-year follow-up, the CSR was 100%, the mean mBI was 0.88 (average reduction: −1.47), the mean PD was 3.35 mm (mean PD reduction: 4.77 mm), and the mean bone defect was reduced by 1.74 mm, with a mean bone fill of 55%. Conclusions The results of the present case series suggest that if accurate surface decontamination is achieved, high survival rate and good clinical and radiographic results can be obtained after 3 years. However, only the histological examination could confirm the growth of new bone in direct contact with the implant surface or if the grafted material only fills the space left by the peri-implant defect.

One-Bone Forearm Reconstruction: A Salvage Solution for the Forearm with Massive Bone Loss.

Salvaging the forearm is a major challenge in cases of massive bone loss from injuries in which the extremity is severely mangled or following bone resection secondary to pathological tissue excision. The purpose of this study was to evaluate the role of one-bone forearm (OBF) reconstruction as a salvage option in these difficult situations. A total of 38 patients with forearm segmental bone loss (acute and chronic) treated between 1995 and 2014 were included (range of follow-up, 2 to 20 years). Sixteen of the patients, 8 with avulsion amputations and 8 with severely mangled extremities, were managed in the emergency department because they required immediate replantation and revascularization, respectively. In the chronic setting, bone loss was due to infection with nonunion in 16 patients, tumor of the radius in 2 patients, and pseudarthrosis of the forearm in 4 patients. The surgical technique included conversion to OBF by achieving union between the distal part of the radius and the proximal part of the ulna in the majority of cases, with distal radioulnar joint (DRUJ) fusion in 4 cases, and ulna to carpals in 5 cases. Direct bone contact was achieved in 16 patients, a free vascularized fibular graft was used to bridge the bone gap in 10 patients, and 12 patients required iliac crest bone-grafting. The mean patient age was 35.5 years (range, 6 to 87 years); there were 23 male and 15 female patients. Among those who underwent OBF for acute injuries, the mean time to union was 7.3 months; 14 patients had complete union, and 2 patients had infection with nonunion requiring secondary procedures. As assessed using the criteria of Chen, 10 patients had a grade-I functional outcome, 3 patients had a grade-II outcome, and 3 patients had a grade-III outcome. In the elective group of 22 patients, the average time to union was 7.1 months. Nonunion was reported for 2 patients. On the basis of the Peterson scoring system, the outcome was excellent for 12 patients, good for 6 patients, fair for 2 patients, and poor for 2 patients. OBF reconstruction is a viable surgical treatment alternative. It is a demanding reconstruction but functions better and is cosmetically more appealing than a forearm amputation. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Incorporation and Remodeling of Structural Allografts in Acetabular Reconstruction: Multiscale, Micro-Morphological Analysis of 13 Pelvic Explants.

Background:Total hip arthroplasty (THA) is frequently accompanied by acetabular bone loss, which constitutes a major challenge in revision procedures. Structural allografts can be implanted to restore a stable osseous foundation for the acetabular prosthesis. As previous studies were limited to clinical data or included very few cases, the extent to which the graft bone is incorporated over time has remained unclear.Methods:Thirteen acetabula were retrieved post mortem, and the incorporation properties of the bone allografts were analyzed using a hierarchical approach of imaging techniques including contact radiography, high-resolution peripheral quantitative computed tomography (HR-pQCT), histological analysis of undecalcified specimens, and quantitative backscattered electron imaging (qBEI). The distance between the current allograft bone and host bone borders (i.e., current overlap) as well as the distance between the original allograft bone and host bone borders (i.e., total ingrowth) were assessed.Results:In 10 of 13 cases, the complete interface (100%) was characterized by direct contact and additional overlap of the allograft bone and host bone, while the remaining 3 cases demonstrated direct contact along 25% to 80% of the interface. The allograft bone showed an intact trabecular structure and significantly higher mineralization compared with the host bone. The mean current overlap (and standard deviation) was 2.3 ± 1.0 mm, with a maximum of 5.3 ± 2.4 mm. Importantly, the total ingrowth reached much further, to a mean of 7.2 ± 2.3 mm (maximum, 10.5 ± 4.0 mm). Neither the time that the allograft was in situ nor the degree of contact between the host and allograft bone correlated with the current overlap and the time in situ did not correlate with total ingrowth.Conclusions:This study showed bone remodeling with subsequent interconnection of the host and allograft bone along the majority of the interface, leading to adequate incorporation of the allograft. The lack of complete incorporation of the graft did not lead to graft collapse up to 22 years after revision surgery.Clinical Relevance:Our study provides the first systematic multiscale evaluation of successfully implanted structural allografts and forms the scientific basis for their clinical use in revision THA.

Endo-sinus bone formation after transalveolar sinus floor elevation without grafting with simultaneous implant placement: Histological and histomorphometric assessment in a dog model.

To evaluate endo-sinus new bone formation and implant osseointegration after transalveolar sinus floor elevation (TSFE) and simultaneous implant placement without any grafting materials and to investigate the influence of implant surface modification on bone healing process under this circumstance. Transalveolar sinus floor elevation and simultaneous implant placement were conducted bilaterally on 12 Labrador dogs. No grafting materials were used during surgery. Implants with two different surfaces (SLA and SLActive) were placed in a split-mouth design. The animals were sacrificed 4, 8 and 24weeks after surgery for histological and histomorphometric assessments. Bone-to-implant contact (BIC%), alveolar bone height (ABH) and the percentages of mineralized bone (MB%) in the area of interest were analysed. The probing depth (PD) and bleeding on probing (BOP) were also assessed to describe peri-implant health conditions. Sprouts of new bone in direct contact with implant surface were seen in the elevated area at every time point. Newly formed woven bone under sinus membrane was visible. SLActive implants exhibited favourable results compared with SLA implants regarding ABH at 4weeks and BIC% at 4 and 8weeks. Sites with BOP positive could be observed in both groups at any time point. No newly formed bone can be found on the implant apex with either SLA or SLActive surfaces at any time point. Spontaneous new bone formation from the parent bone walls could be observed after TFE without any grafting materials. No clear evidence of bone formation from the Schneiderian membrane could be found. Even though there were trends for quicker bone response of SLActive implants, this study failed to show the absolute advantage of SLActive in achieving endo-sinus bone formation.

Relapse related to pushing and rebounding action in maxillary anterior downgraft with mandibular setback surgery

PurposeMaxillary downgraft (MD) and mandibular setback (MS) are problematic procedures in terms of postoperative stability. While the amount of intraoperative clockwise rotation (CWR) of the proximal segment (PS) after MS combined with MD has a positive correlation with the amount of MD, mandibular relapse after MS with MD in relation to intraoperative CWR of the PS has not been reported. Moreover, the effect of mandibular relapse on maxillary stability after MS with MD remains unclear. The purpose of this study is to evaluate mandibular and maxillary stability after MS with MD in relation to intraoperative CWR of the PS and amount of MD. Materials and MethodsThe study included 57 patients who underwent bimaxillary orthognathic surgery. Patients were classified into two groups according to whether MD was performed or not performed: Group I had 2 mm or more MD; and Group II had less than 2 mm MD including vertical impaction or no vertical changes. The amount of surgical movement and postoperative relapse were cephalometrically evaluated and statistically analyzed. ResultsThere was no significant difference in MS between Groups I and II, however, the vertical movement of the maxilla was different significantly (p < 0.001). In Group I, the intraoperative CWR and postoperative CCWR of the PS was greater than that of Group II (p = 0.010; p < 0.001, respectively). Consequently, the anterior relapse of the mandible was greater in Group I than in Group II despite the same amount of MS in Groups I and II. In Group I, with direct bone contact using Le Fort I inclined osteotomy, vertical relapse at point A showed no statistical correlation with anterior relapse at point B, while the vertical and horizontal dental relapse at U1 showed significant correlations with anterior relapse at point B (r = −0.403, p = 0.030; r = 0.581, p < 0.001, respectively). ConclusionFor more stable results, Le Fort I inclined osteotomy is recommended to obtain direct bone contact when moving the maxilla inferiorly. The PS must also be fixed while maintaining vertical bone step to prevent CWR.

Osteoblast response to disordered nanotopography

The ability to influence stem cell differentiation is highly desirable as it would help us improve clinical outcomes for patients in various aspects. Many different techniques to achieve this have previously been investigated. This concise study, however, has focused on the topography on which cells grow. Current uncemented orthopaedic implants can fail if the implant fails to bind to the surrounding bone and, typically, forms a soft tissue interface which reduces direct bone contact. Here, we look at the effect of a previously reported nanotopography that utilises nanodisorder to influence mesenchymal stromal cell (as may be found in the bone marrow) differentiation towards bone and to also exert this effect on mature osteoblasts (as may be found in the bone). As topography is a physical technique, it can be envisaged for use in a range of materials such as polymers and metals used in the manufacture of orthopaedic implants.

Micro- to Macroroughness of Additively Manufactured Titanium Implants in Terms of Coagulation and Contact Activation.

This study aimed to evaluate how as-built electron beam melting (EBM) surface properties affect the onset of blood coagulation. The properties of EBM-manufactured implant surfaces for placement have, until now, remained largely unexplored in literature. Implants with conventional designs and custom-made implants have been manufactured using EBM technology and later placed into the human body. Many of the conventional implants used today, such as dental implants, display modified surfaces to optimize bone ingrowth, whereas custom-made implants, by and large, have machined surfaces. However, titanium in itself demonstrates good material properties for the purpose of bone ingrowth. Specimens manufactured using EBM were selected according to their surface roughness and process parameters. EBM-produced specimens, conventional machined titanium surfaces, as well as PVC surfaces for control were evaluated using the slide chamber model. A significant increase in activation was found, in all factors evaluated, between the machined samples and EBM-manufactured samples. The results show that EBM-manufactured implants with as-built surfaces augment the thrombogenic properties. EBM that uses Ti6Al4V powder appears to be a good manufacturing solution for load-bearing implants with bone anchorage. The as-built surfaces can be used "as is" for direct bone contact, although any surface treatment available for conventional implants can be performed on EBM-manufactured implants with a conventional design.

Histomorphological and Histomorphometric Analyses of Grade IV Commercially Pure Titanium and Grade V Ti-6Al-4V Titanium Alloy Implant Substrates: An In Vivo Study in Dogs.

To evaluate the bone response to grade IV commercially pure titanium (G4) relative to Ti-6Al-4V (G5). Implant surface topography was characterized by optical interferometry and scanning electron microscopy (SEM). Thirty-six implants (Signo Vinces, n = 18 per group) were installed in the radius of 18 dogs. The animals were killed at 1, 3, and 6 weeks, resulting in 6 implants per group and time in vivo for bone morphology, bone-to-implant contact (BIC), and bone area fraction occupancy (BAFO) evaluation. SEM depicted a more uniform topography of G4 than G5. Surfaces were statistically homogeneous for Sa, Sq, and Sdr. At 1 week, new bone formation was observed within the healing connective tissue in contact with the implant surface. At 3 weeks, new bone in direct contact with the implant surface was observed at all bone regions. At 6 weeks, the healing chambers filled with woven bone depicted an onset of replacement by lamellar bone. No significant effect of substrate was detected. Time presented an effect on BIC and BAFO (P < 0.001). Both titanium substrates were biocompatible and osseoconductive at the bone tissue level.

Does PEEK/HA Enhance Bone Formation Compared With PEEK in a Sheep Cervical Fusion Model?

BackgroundPolyetheretherketone (PEEK) has a wide range of clinical applications but does not directly bond to bone. Bulk incorporation of osteoconductive materials including hydroxyapatite (HA) into the PEEK matrix is a potential solution to address the formation of a fibrous tissue layer between PEEK and bone and has not been tested.Questions/purposesUsing in vivo ovine animal models, we asked: (1) Does PEEK-HA improve cortical and cancellous bone ongrowth compared with PEEK? (2) Does PEEK-HA improve bone ongrowth and fusion outcome in a more challenging functional ovine cervical fusion model?MethodsThe in vivo responses of PEEK-HA Enhanced and PEEK-OPTIMA® Natural were evaluated for bone ongrowth in the form of dowels implanted in the cancellous and cortical bone of adult sheep and examined at 4 and 12 weeks as well as interbody cervical fusion at 6, 12, and 26 weeks. The bone-implant interface was evaluated with radiographic and histologic endpoints for a qualitative assessment of direct bone contact of an intervening fibrous tissue later. Gamma-irradiated cortical allograft cages were evaluated as well.ResultsIncorporating HA into the PEEK matrix resulted in more direct bone apposition as opposed to the fibrous tissue interface with PEEK alone in the bone ongrowth as well as interbody cervical fusions. No adverse reactions were found at the implant–bone interface for either material. Radiography and histology revealed resorption and fracture of the allograft devices in vivo.ConclusionsIncorporating HA into PEEK provides a more favorable environment than PEEK alone for bone ongrowth. Cervical fusion was improved with PEEK-HA compared with PEEK alone as well as allograft bone interbody devices.Clinical RelevanceImproving the bone–implant interface with a PEEK device by incorporating HA may improve interbody fusion results and requires further clinical studies.

Inkjet printed periodical micropatterns made of inert alumina ceramics induce contact guidance and stimulate osteogenic differentiation of mesenchymal stromal cells.

Bioinert high performance ceramics exhibit detrimental features for implant components with direct bone contact because of their low osseointegrating capability. We hypothesized that periodical microstructures made of inert alumina ceramics can influence the osteogenic differentiation of human mesenchymal stromal cells (hMSC). In this study, we manufactured pillared arrays made of alumina ceramics with periodicities as low as 100μm and pillar heights of 40μm employing direct inkjet printing (DIP) technique. The response of hMSC to the microstructured surfaces was monitored by measuring cell morphology, viability and formation of focal adhesion complexes. Osteogenic differentiation of hMSCs was investigated by alkaline phosphatase activity, mineralization assays and expression analysis of respective markers. We demonstrated that MSCs react to the pillars with contact guidance. Subsequently, cells grow onto and form connections between the microstructures, and at the same time are directly attached to the pillars as shown by focal adhesion stainings. Cells build up tissue-like constructs with heights up to the micropillars resulting in increased cell viability and osteogenic differentiating properties. We conclude that periodical micropatterns on the micrometer scale made of inert alumina ceramics can mediate focal adhesion dependent cell adhesion and stimulate osteogenic differentiation of hMSCs.