Alveolar ridge augmentation using anodized implants coated with Escherichia coli–derived recombinant human bone morphogenetic protein 2

Effect of Platelet-Rich Fibrin and Bone Morphogenetic Protein on Dental Implant Stability

Recombinant human bone morphogenetic protein-2 (rhBMP-2) and platelet-rich fibrin (PRF) bioactive materials have been used to enhance healing and improve dental implant stability. This study aimed to compare the effect of rhBMP-2 and PRF bioactive materials on dental implant stability at different intervals and to evaluate the correlation of implant length and diameter with implant stability.Two bioactive materials were compared to evaluate their effect on dental implant stability. A total of 32 patients (102 dental implants) were divided into 3 groups: 24 dental implants with bone morphogenetic protein (BMP), 27 dental implants with PRF, and 51 dental implants without BMP or PRF (control group). Data were statistically analyzed to determine the bioactive material with the best effect on implant stability.Implant stability did not significantly differ between the groups immediately after implant insertion (first reading; P > 0.05). The implant stability of the rhBMP-2 group was significantly better than those of the PRF and control groups 6 weeks after implant insertion (second reading; P = 0.001). After 12 weeks, the effect of rhBMP-2 on implant stability was highly significant and better than that of the other groups (third reading; P < 0.001).Dental implants coated with BMP have a better effect on stability than those with PRF alone and those without PRF or BMP.

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.

Enhancement of osseointegration by direct coating of rhBMP-2 on target-ion induced plasma sputtering treated SLA surface for dental application

Owing to the excellent bioactive properties of recombinant human bone morphogenetic proteins (rhBMPs), dentistry considers them as a fascinating adjuvant alternative for enhancing bone regeneration and bone-to-implant junction in the early implantation stages. However, stable loading and delivery efficiency of rhBMPs on the implant surfaces involve major concerns because of the harsh wearing condition under load during implantation. In this study, to achieve successful rhBMP-2 delivery, a nanoporous surface structure is introduced on the sandblasting with large grit and acid-etching (SLA)-treated titanium (Ti) surface via the tantalum (Ta) target-ion induced plasma sputtering (TIPS) technique. Unlike oxidation-induced surface nanoporous fabrications on a Ti surface, TIPS-treated surfaces provide excellent structural unity of the nanoporous structure with the substrate due to their etching-based fabrication mechanism. SLA/TIPS-treated Ti exhibits distinct nanoporous structures on the microscale surface geometry and better hydrophilicity compared with SLA-treated Ti. A sufficiently empty nanoporous surface structure combined with the hydrophilic property of SLA/TIPS-treated Ti facilitates the formation of a thick and uniform coating layer of rhBMP-2 on the surface without any macro- and microcoagulation. Compared with the SLA-treated Ti surface, the amount of coated rhBMP-2 increases up to 63% on the SLA/TIPS-treated Ti surface. As a result, the in vitro pre-osteoblast cell response of the SLA/TIPS-treated Ti surface, especially cell adhesion and differentiation behaviors, improves remarkably. A bone-regenerating direct comparison between the rhBMP-2-coated SLA-treated and SLA/TIPS-treated Ti is conducted on a defective dog mandible model. After 8 weeks of implantation surgery, SLA/TIPS-treated Ti with rhBMP-2 exhibits a better degree of contact area for the implanted bone, which mineralizes new bones around the implant. Quantitative results of bone-in-contact ratio and new bone volume also show significantly higher values for the SLA/TIPS-treated Ti with the rhBMP-2 specimen. These results confirm that an SLA/TIPS-treated surface is a suitable rhBMP-2 carrier for a dental implant to achieve early and strong osseointegration of Ti dental implants.

A systematic review and meta-analysis on the influence of biological implant surface coatings on periimplant bone formation

This systematic review and meta-analysis evaluated the influence of biological implant surface coatings on periimplant bone formation in comparison to an uncoated titanium reference surface in experimental large animal models. The analysis was structured according to the PRISMA criteriae. Of the1077 studies, 30 studies met the inclusion criteriae. Nineteen studies examined the bone implant contact (BIC) and were included in the meta-analysis. Overall, the mean increase in BIC for the test surfaces compared to the reference surfaces was 3.7 percentage points (pp) (95% CI -3.9-11.2, p = 0.339). Analyzing the increase in BIC for specific coated surfaces in comparison to uncoated reference surfaces, inorganic surface coatings showed a significant mean increase in BIC of 14.7 pp (95% CI 10.6-18.9, p < 0.01), extracellular matrix (ECM) surface coatings showed an increase of 10.0 pp (95% CI 4.4-15.6, p < 0.001), and peptide coatings showed a statistical trend with 7.1 pp BIC increase (95% CI -0.8-15.0, p = 0.08). In this review, no statistically significant difference could be found for growth factor surface coatings (observed difference -3.3 pp, 95% CI -16.5-9.9, p = 0.6). All analyses are exploratory in nature. The results show a statistically significant effect of inorganic and ECM coatings on periimplant bone formation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2898-2910, 2016.

Effects of rhBMP-2 on Sandblasted and Acid Etched Titanium Implant Surfaces on Bone Regeneration and Osseointegration: Spilt-Mouth Designed Pilot Study

This study was conducted to evaluate effects of rhBMP-2 applied at different concentrations to sandblasted and acid etched (SLA) implants on osseointegration and bone regeneration in a bone defect of beagle dogs as pilot study using split-mouth design. Methods. For experimental groups, SLA implants were coated with different concentrations of rhBMP-2 (0.1, 0.5, and 1 mg/mL). After assessment of surface characteristics and rhBMP-2 releasing profile, the experimental groups and untreated control groups (n = 6 in each group, two animals in each group) were placed in split-mouth designed animal models with buccal open defect. At 8 weeks after implant placement, implant stability quotients (ISQ) values were recorded and vertical bone height (VBH, mm), bone-to-implant contact ratio (BIC, %), and bone volume (BV, %) in the upper 3 mm defect areas were measured. Results. The ISQ values were highest in the 1.0 group. Mean values of VBH (mm), BIC (%), and BV (%) were greater in the 0.5 mg/mL and 1.0 mg/mL groups than those in 0.1 and control groups in buccal defect areas. Conclusion. In the open defect area surrounding the SLA implant, coating with 0.5 and 1.0 mg/mL concentrations of rhBMP-2 was more effective, compared with untreated group, in promoting bone regeneration and osseointegration.

Effects of different rhBMP-2 release profiles in defect areas around dental implants on bone regeneration

This study was undertaken to evaluate the effects of different rhBMP-2 release profiles in defect areas around dental implants on osseointegration and bone regeneration. Four beagle dogs (13-15 kg) were used. The defect was 3 mm deep and there was a 1 mm gap around the implant. Each of the four implants was installed on the right and left mandibular alveolar ridges. After the implants were placed, experimental groups were applied to the surrounding defect area (n = 8 in each group, the control group was not treated). The inject group was injected with rhBMP-2 solution directly. In the gel group, rhBMP-2 mixed with a hydrogel matrix was applied. In the particle-gel group, rhBMP-2-embedded poly(lactic-co-glycolic acid)(PLGA) microparticles mixed with hydrogel matrix were applied to maintain consistent release. Sequential fluorescent labeling and histological analysis were performed to evaluate the new bone formation and osseointegration in the defect area. In the control group, larger marginal bone loss was detected as compared with the other groups (P  <  0.05). The gel group showed significantly higher levels of BIC in the buccal and lingual defect areas compared with the other groups (P  <  0.05). New-bone percentages in the inject and gel groups formed more new bone than in the particle-gel and control groups (P  <  0.05). Despite the limitations of this study, the use of only hydrogel, which allows early release of rhBMP-2 followed by consistent extended release, showed better bone formation and osseointegration than simple injection or PLGA microparticles with hydrogel matrix.

BMP-functionalised coatings to promote osteogenesis for orthopaedic implants

The loss of bone integrity can significantly compromise the aesthetics and mobility of patients and can be treated using orthopaedic implants. Over the past decades; various orthopaedic implants; such as allografts; xenografts and synthetic materials; have been developed and widely used in clinical practice. However; most of these materials lack intrinsic osteoinductivity and thus cannot induce bone formation. Consequently; osteoinductive functionalisation of orthopaedic implants is needed to promote local osteogenesis and implant osteointegration. For this purpose; bone morphogenetic protein (BMP)-functionalised coatings have proven to be a simple and effective strategy. In this review; we summarise the current knowledge and recent advances regardingBMP-functionalised coatings for orthopaedic implants.

The effect of anodized implants coated with combined rhBMP-2 and recombinant human vascular endothelial growth factors on vertical bone regeneration in the marginal portion of the peri-implant

OBJECTIVES

The aim of this study was to evaluate the effect of anodized implants coated with combined rhBMP-2 and recombinant human vascular endothelial growth factors (rhVEGFs) on vertical bone regeneration in the marginal portion of the peri-implant.

STUDY DESIGN

Supra-alveolar defects were created in 3 male beagle dogs. Each animal received 8 implants that were either coated with a single growth factor (rhBMP-2) or combined growth factors (rhBMP-2 + rhVEGF), or an anodized implant (the control group). The amount of the vertical bone regeneration, the bone-implant contact, and the intrathread bone density were investigated using histomorphometric analysis at 8 weeks.

RESULTS

The bone morphogenetic protein (BMP) group and the BMP-VEGF group showed vertical alveolar bone regeneration and enhanced bone-implant contact in the microthread compared with the control group (P < .05).

CONCLUSIONS

Anodized implants coated with rhBMP-2 and rhBMP - 2 + rhVEGF can induce vertical alveolar bone regeneration, but the combined effect of rhBMP-2 and rhVEGF was not verified.

Comparative study of Chinese hamster ovary cell versus Escherichia coli-derived bone morphogenetic protein-2 using the critical-size supraalveolar peri-implant defect model

BACKGROUND

Chinese hamster ovary (CHO) cell-derived recombinant human bone morphogenetic protein-2 (rhBMP-2) has been introduced for spine, long bone, and craniofacial indications. Escherichia coli- (E. coli) derived rhBMP-2 displays comparable efficacy to CHO cell-derived rhBMP-2 in vitro and in small-animal models. The objective of this study is to evaluate the efficacy of E. coli-derived rhBMP-2 compared to the benchmark CHO cell-derived rhBMP-2 using an established large-animal model.

METHODS

Contralateral, critical-size supraalveolar peri-implant defects in six adult male Hound Labrador mongrel dogs received CHO cell- or E. coli-derived rhBMP-2 (0.2 mg/mL) in an absorbable collagen sponge (ACS) carrier. In each quadrant, three dental implants were placed. A titanium mesh device was used to support space provision. The animals received fluorescent bone markers for qualitative evaluations. Animals were euthanized at 8 weeks for histopathologic and histometric evaluation.

RESULTS

Clinical healing included significant swelling, but none of the animals experienced wound dehiscences. CHO cell- and E. coli-derived rhBMP-2 supported comparable bone formation (new bone area, 35.8 ± 3.6 versus 30.1 ± 2.2 mm(2); bone density, 31.8% ± 1.6% versus 35.6% ± 2.5%; and osseointegration, 32.9% ± 7.4% versus 33.7% ± 8.1%) without statistically significant differences between treatments. Newly formed immature delicate trabecular bone in fibrovascular marrow filled the space underneath the titanium mesh and extended coronally above the mesh. Seroma formation was frequently observed. There were no discernable qualitative histologic differences between treatments.

CONCLUSION

CHO cell- and E. coli-derived rhBMP-2 in an ACS carrier appear equally effective at inducing local bone formation in support of dental implant osseointegration.