Sinus augmentation using rhBMP-2/ACS in a mini-pig model: relative efficacy of autogenous fresh particulate iliac bone grafts

Sinus augmentation with poly(ε)caprolactone-β tricalcium phosphate scaffolds, mesenchymal stem cells and platelet rich plasma for one-stage dental implantation in minipigs

PURPOSE

This study evaluated the efficacy of a tube-shaped poly(ε) caprolactone - β tricalcium phosphate (PCL-TCP) scaffold with the incorporation of human umbilical cord-derived mesenchymal stem cells (hUCMSCs) and platelet-rich plasma (PRP) for bone regeneration in the procedure of single-stage sinus augmentation and dental implantation in minipigs.

METHODS

Implants were placed in the bilateral sides of the maxillary sinuses of 5 minipigs and allocated to a PCL-TCP+hUCMSCs+PRP group (n=5), a PCL-TCP+PRP group (n=5), and a PCL-TCP-only group (n=6). After 12 weeks, bone regeneration was evaluated with soft X-rays, micro-computed tomography, fluorescence microscopy, and histomorphometric analysis.

RESULTS

Four implants failed (2 each in the PCL-TCP+hUCMSCs+PRP and PCL-TCP+hUCMSC groups). An analysis of the grayscale levels and bone-implant contact ratio showed significantly higher mean values in the PCL-TCP+hUCMSCs+PRP than in the PCL-TCP group (P=0.045 and P=0.016, respectively). In fluoromicroscopic images, new bone formation around the outer surfaces of the scaffolds was observed in the PCL-TCP+hUCMSCs+PRP group, suggesting a tenting effect of the specially designed scaffolds. Bone regeneration at the scaffold-implant interfaces was observed in all 3 groups.

CONCLUSIONS

Using a tube-shaped, honeycombed PCL-TCP scaffold with hUCMSCs and PRP may serve to enhance bone formation and dental implants' osseointegration in the procedure of simultaneous sinus lifting and dental implantation.

MiR-20a promotes osteogenic differentiation in bone marrow-derived mesenchymal stem/stromal cells and bone repair of the maxillary sinus defect model in rabbits

Introduction: This study aimed to determine whether miR-20 promoted osteogenic differentiation in bone marrow-derived mesenchymal stem/stromal cells (BMSCs) and accelerated bone formation in the maxillary sinus bone defect model in rabbits. Methods: BMSCs were transfected with miR-20a or anti-miR-20a for 12 h, followed by detection of RUNX2, Sp7 mRNA, bone morphogenetic protein 2 (BMP2), and RUNX2 protein expression. Alkaline phosphatase (ALP) activity and Alizarin Red S staining were used to detect calcified nodule deposition. In the rabbit maxillary sinus bone defect model, miR-20a loaded with AAV and BMP2 protein were mixed with Bio-Oss bone powder for filling the bone defect. At 4 weeks and 8 weeks, bone density was detected by cone beam computed tomography (CBCT), and new bone, osteoblasts, and collagen type 1 were evaluated by hematoxylin and eosin (HE) staining and immunohistochemical (IHC) staining. Results: Overexpression of miR-20a enhanced the mRNA and protein levels of BMP2, RUNX2, and SP7, the activity of ALP, and the levels of matrix mineralization, whereas the levels and activity of the aforementioned factors were decreased by anti-miR-20a treatment of BMSCs. Furthermore, miR-20a significantly increased the bone density, the number of osteoblasts, and the secretion of collagen type 1 in bone defects compared with Bio-Oss bone powder in the rabbit maxillary sinus bone defect model. Conclusion: Overall, miR-20a can induce osteogenic differentiation in BMSCs and accelerate bone formation of maxillary sinus defects in rabbits.

The recent advances in scaffolds for integrated periodontal regeneration

The periodontium is an integrated, functional unit of multiple tissues surrounding and supporting the tooth, including but not limited to cementum (CM), periodontal ligament (PDL) and alveolar bone (AB). Periodontal tissues can be destructed by chronic periodontal disease, which can lead to tooth loss. In support of the treatment for periodontally diseased tooth, various biomaterials have been applied starting as a contact inhibition membrane in the guided tissue regeneration (GTR) that is the current gold standard in dental clinic. Recently, various biomaterials have been prepared in a form of tissue engineering scaffold to facilitate the regeneration of damaged periodontal tissues. From a physical substrate to support healing of a single type of periodontal tissue to multi-phase/bioactive scaffold system to guide an integrated regeneration of periodontium, technologies for scaffold fabrication have emerged in last years. This review covers the recent advancements in development of scaffolds designed for periodontal tissue regeneration and their efficacy tested in vitro and in vivo. Pros and Cons of different biomaterials and design parameters implemented for periodontal tissue regeneration are also discussed, including future perspectives.

Maxillary Sinus Floor Augmentation with Autogenous Bone Graft Alone Compared with Alternate Grafting Materials: a Systematic Review and Meta-Analysis Focusing on Histomorphometric Outcome

Objectives

The objective of present systematic review was to test the hypothesis of no difference in histomorphometric outcome after maxillary sinus floor augmentation with autogenous bone graft alone compared with alternate grafting materials applying the lateral window technique.

Material and Methods

MEDLINE (PubMed), Embase and Cochrane library search in combination with hand-search of relevant journals were conducted. Human studies published in English until the 25^th of March, 2020 were included. Histomorphometric outcomes were evaluated by descriptive statistics and meta-analysis including 95% confidence interval (CI).

Results

Electronic search and hand-searching resulted in 1902 entries. Sixteen randomized controlled trials with unclear risk of bias fulfilled the inclusion criteria. Descriptive statistics showed comparable or improved histomorphometric outcomes with autogenous bone graft. Meta-analysis revealed a mean difference of -7.1% (CI = -11.0 to -3.2) indicating a significant higher amount of bone after maxillary sinus floor augmentation with autogenous bone graft compared with alternate grafting materials. Subgroup analysis demonstrated a non-significantly differences of -3.7% (CI = -10.9 to 3.4), -11.5% (CI = -25.9 to 2.8), 2.2% (CI = -16.9 to 21.3), and -4.6% (CI = -14.4 to 5.2), when autogenous bone graft was compared with allogeneic bone graft, xenograft, composite grafting materials involving xenograft or synthetic biomaterial mixed with autogenous bone graft, respectively.

Conclusions

Maxillary sinus floor augmentation with autogenous bone graft seems to facilitate improved histomorphometric outcomes compared with alternate grafting materials. However, the included studies were characterised by an unclear risk of bias and various methodological confounding factors. Hence, the conclusions drawn from the results of present study should be interpreted with caution.

Synergism between recombinant human bone morphogenetic protein 2/absorbable collagen sponge and bone substitutes favors vertical bone augmentation and the resorption rate of the biomaterials: Histomorphometric and 3D microcomputed tomography analysis

BACKGROUND

Recombinant human bone morphogenetic protein 2 (rhBMP-2) is an osteoinductor frequently used for bone regeneration in oral and maxillofacial surgery. There is no consensus about the ideal carrier for this growth factor. The aim of this study was to compare the bone augmentation, bone microarchitecture, and biodegradation rate of additional carriers to rhBMP-2/absorbable collagen sponge (ACS) in a vertical guided bone regeneration model.

METHODS

Four titanium cylinders were fixed onto the calvaria of rabbits (n = 20) that received (n = 10) or not (n = 10) rhBMP-2/ACS in conjunction with one of the carriers: beta-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP), bovine bone mineral (BBM) or blood clot. The samples were analyzed by means of microcomputed tomography and histomorphology after 14 weeks.

RESULTS

All the materials with rhBMP-2/ACS exhibited improvement on bone augmentation, mainly BCP (P = 0.033) and β-TCP (P = 0.038), in the upper portion of the cylinder. Although trabecular anisotropy was improved in all the materials groups, trabecular connectivity was diminished when the biomaterials received rhBMP-2/ACS. Resorption rate of the remaining biomaterial was improved by rhBMP-2/ACS, mainly in BBM (P <0.01) and β-TCP (P <0.01). BBM exhibited the highest osteoclast density compared with the other materials groups.

CONCLUSIONS

BCP and β-TCP biomaterials exhibited a synergic effect with rhBMP-2/ACS, acting as suitable and viable carriers for vertical bone augmentation. The addition of rhBMP-2 significantly affected the biodegradation of β-TCP and BBM, accelerating the resorption of these materials.

Immediate nonfunctional loading of implants placed simultaneously using computer-guided flapless maxillary crestal sinus augmentation with bone morphogenetic protein-2/collagen matrix

BACKGROUND

Immediate loading has shown positive results for total, partial, or single edentulism. The effects of BMP-2 addition to graft materials on bone formation and implant stability in the early stages of healing have rarely been studied, especially in patients with severely atrophic maxillae.

PURPOSE

To evaluate the effects of simultaneously placed immediate non-functional loaded implants and bone morphogenetic protein-2 (BMP-2)-loaded Bio-Oss collagen, on bone formation and implant stability during the early healing stages of patients with a severely atrophic posterior maxilla using crestal approach.

MATERIALS AND METHODS

Thirty-three cases presenting posterior maxillary residual alveolar bone height of 1-3 mm were evaluated. Flapless crestal sinus augmentation surgery was performed using BMP-2-loaded Bio-Oss collagen, with non-functional implants immediately loaded after surgery. The bone height was assessed using preoperative and postoperative cone beam computed tomography (CBCT). Bone density of the sinus graft sites and implant stability (after 3 months) were evaluated using postoperative CBCT scans and Periotest, respectively. The periodontal parameters and marginal bone loss around the implant were checked after 37.3 months of final prosthesis.

RESULTS

The survival rate of the implants was 100% and the gingiva around the implants remained healthy. All implants remained integrated, and all sinus grafts showed radiographic bone formation. The results indicated high level of bone density and good implant stability, showing minimal marginal bone loss after 37.3 months.

CONCLUSION

This technique could be used in the posterior maxillary region exhibiting poor bone quantity.

Bone formation following sinus grafting with an alloplastic biphasic calcium phosphate in Lanyu Taiwanese mini-pigs

BACKGROUND

To evaluate the new bone formation after grafting with a synthetic biphasic calcium phosphate in sinuses with minimal bone height, the alloplastic and xenograft materials were compared after grafting into Lanyu Taiwanese mini-pig sinuses via split-mouth design.

METHODS

In six mini-pigs, synthetic hydroxyapatite/tricalcium phosphate (HA/TCP) particles were inserted into one of the sinus cavities using the extra-oral approach, where deproteinized bovine bone mineral (DBBM) particles were placed contralaterally. Fluorescent bony labels of Alizarin and Calcein green were delivered at weeks 4 and 8, respectively. Animals were sacrificed at week 12 and the augmented tissues were evaluated by cone-beam computed tomography, microcomputed tomography, and histology.

RESULTS

By radiographic examination, the mean thicknesses of sinus cortexes for DBBM and HA/TCP groups were similar (0.35 versus 0.38 cm) and the mean volumes augmented were also indifferent (1.29 versus 1.64 cm³ ). The distributions of bones, residual particles, and non-mineralized tissues in augmented masses between groups were undistinguishable. Under microscopy, however, macroporosities of osteons were filled with HA/TCP residual particles, whereas the newly formed bones lay on top of DBBM particle surfaces. Although the mineral deposition rates between groups were indifferent, the mean labeled surface in the HA/TCP group was significantly greater than those in the DBBM group at week 4 (35.16% versus 14.00% for HA/TCP and DBBM, respectively) but less than that at week 8 (19.33% versus 39.16%, respectively).

CONCLUSION

Sinus augmentation with synthetic HA/TCP and DBBM exhibited similar effectiveness in new bone formation.

Proof-of-concept study of vertical augmentation using block-type allogenic bone grafts: A preclinical experimental study on rabbit calvaria

This study aimed to quantify the healing following vertical augmentation of allogenic bone blocks with/without recombinant human bone morphogenetic protein-2 (rhBMP-2) on rabbit calvaria. Experiments were performed using allogenic bone blocks which were grafted bilaterally with or without rhBMP-2 on 20 rabbit calvaria, and these animals were divided to four groups according to the use of rhBMP-2 and healing periods (2 and 8 weeks; n = 10 in each group). Onlay-type bone blocks (8 mm in diameter and 5 mm high) were fixed with a self-tapping screw after removing the cortex in the control group, and the same protocol was applied with the addition of soaking the bone blocks with rhBMP-2 for 15 min in the test group. Radiographic and histologic analyses were performed after 2 or 8 weeks to evaluate the volumetric stability and bone regeneration within the grafted area. The radiographic analysis revealed that the height of the allogenic bone block decreased but its volume was maintained from 2 to 8 weeks in both the control and test groups. The histologic results demonstrated a statistically significant increase in new bone area in the test group, especially in the lower region adjacent to the preexisting calvarial floor. The amount of newly formed bone in all regions of the augmented bone blocks in both the control and test groups was greater at 8 weeks than at 2 weeks. In conclusion, the vertically grafted allogenic bone block maintained its volume with new bone formation, and this was accelerated by the addition of rhBMP-2. These findings indicate that allogenic bone block soaked with rhBMP-2 could be a useful candidate biomaterial for vertical augmentation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2700-2707, 2018.

Sinus augmentation using a mini-pig model: Effect of ceramic and allogeneic bone biomaterials

BACKGROUND

Present clinical practice broadly relies on off-the-shelf allogeneic, xenogeneic or synthetic bone biomaterials in support of sinus augmentation. Also, recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge carrier (rhBMP-2/ACS) has been shown to support clinically relevant bone formation when used to augment the maxillary sinus.

OBJECTIVES

To evaluate local bone formation/dental implant osseointegration following implantation of two particulate bone biomaterials using the mini-pig sinus augmentation model.

METHODS

Nine adult Göttingen mini-pigs were used for evaluation of a biphasic ceramic (15%/85% HA/ß-TCP) and an allogeneic mineralized bone biomaterial. Treatments randomized to contralateral sinus sites included sham-surgery (control) and biomaterials. Two threaded dental implants (ø4.0 × 11.5 mm) were placed at each sinus site. The animals were euthanized at 8 weeks for histologic analysis.

RESULTS

Execution of the surgical protocol and healing was unremarkable. Limited infraorbital swelling was observed until suture removal. The biphasic ceramic and allogeneic bone biomaterials produced significantly increased bone formation (5.2 ± 1.9 mm and 4.9 ± 1.6 mm vs. 2.6 ± 0.5 mm, p < 0.05) and osseointegration (18.0 ± 6.0% and 25.1 ± 18.2% vs. 10.1 ± 8.0%, p < 0.05) over the sham-surgery control. No significant differences were observed between biomaterials.

CONCLUSIONS

Implantation of biphasic ceramic or allogeneic bone biomaterials enhances bone formation in the mini-pig maxillary sinus, however, dental implant bone support is incomplete resulting in overall limited osseointegration.

Comparison of recombinant human bone morphogenetic protein-2-infused absorbable collagen sponge, recombinant human bone morphogenetic protein-2-coated tricalcium phosphate, and platelet-rich fibrin-mixed tricalcium phosphate for sinus augmentation in rabbits

Background/purpose

Numerous grafting materials have been used in the bone regeneration of maxillary sinus to obtain a sufficient amount of new bone in implant dentistry. The objective of this study was to compare the potentials of Type I absorbable collagen sponge (ACS) impregnated with recombinant human bone morphogenetic protein (rhBMP)-2, rhBMP-2-coated tricalcium phosphate (TCP), platelet-rich fibrin-mixed TCP for enhancing bone regeneration in sinus augmentation in rabbits.

Materials and methods

The sinus defects were grafted with rhBMP-2+ACS (Group A), rhBMP-2-coated TCP (Group B), and platelet-rich fibrin-mixed TCP (Group C). The specimens underwent decalcification, and were stained for histomorphometric analysis.

Results

There were no significant differences in inflammatory features among the groups 1-week postoperation. In a histomorphometric analysis, the new bone formation ratio showed significant differences between groups at 2 weeks. rhBMP-2+ACS showed a larger and more rapid bone formation area at 2 weeks than those of Groups B and C.

Conclusion

Our histological evaluation demonstrates that Type I ACS can be used as a carrier of rhBMP-2, and rhBMP-2+ACS showed rapid bone formation, remodeling, and calcification at Week 2 in rabbit.

Bone Regenerative Efficacy of Limited-Dose Escherichia Coli-Derived rhBMP-2 With Biphasic Calcium Phosphate Carrier in Rabbit Calvarial Defect Model

PURPOSE

The aim of this study was to characterize the healing in rabbit calvarial bone defects after delivery of limited-dose (1.5 μg) Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2), and evaluate biphasic calcium phosphate (BCP) as a carrier.

MATERIALS AND METHODS

Four 8-mm diameter circular calvarial bone defects were made in 16 rabbits and filled with one of the following: (1) nothing, (2) BCP alone, (3) ErhBMP-2-loaded absorbable collagen sponge (ACS), or (4) ErhBMP-2-loaded BCP. The animals were allowed to heal for either 2 or 8 weeks and were evaluated in clinical, microcomputed tomographic, histological, and histomorphometric analyses.

RESULTS

Microcomputed tomography revealed extensive new bone formation in both of the limited-dose ErhBMP-2-loaded groups. However, bony collapse of the upper defect borders was found in the ErhBMP-2-loaded ACS group. Histomorphometric examination revealed significantly greater new bone formation at 8 weeks than at 2 weeks in all 4 groups (P < 0.05). Both new bone formation and the size of the augmented area differed significantly between the ErhBMP-2-loaded BCP group (6.88 ± 0.74 and 19.62 ± 0.77) and the ErhBMP-2-loaded ACS group (3.04 ± 0.27 and 5.41 ± 0.43) at 8 weeks of healing.

CONCLUSION

ErhBMP-2 promotes bone regeneration in rabbit calvarial defects, even at a limited dose (1.5 μg). The results of this study suggest that BCP is the more efficient carrier for this protein than ACS.

Animal models for periodontal regeneration and peri-implant responses

Translation of experimental data to the clinical setting requires the safety and efficacy of such data to be confirmed in animal systems before application in humans. In dental research, the animal species used is dependent largely on the research question or on the disease model. Periodontal disease and, by analogy, peri-implant disease, are complex infections that result in a tissue-degrading inflammatory response. It is impossible to explore the complex pathogenesis of periodontitis or peri-implantitis using only reductionist in-vitro methods. Both the disease process and healing of the periodontal and peri-implant tissues can be studied in animals. Regeneration (after periodontal surgery), in response to various biologic materials with potential for tissue engineering, is a continuous process involving various types of tissue, including epithelia, connective tissues and alveolar bone. The same principles apply to peri-implant healing. Given the complexity of the biology, animal models are necessary and serve as the standard for successful translation of regenerative materials and dental implants to the clinical setting. Smaller species of animal are more convenient for disease-associated research, whereas larger animals are more appropriate for studies that target tissue healing as the anatomy of larger animals more closely resembles human dento-alveolar architecture. This review focuses on the animal models available for the study of regeneration in periodontal research and implantology; the advantages and disadvantages of each animal model; the interpretation of data acquired; and future perspectives of animal research, with a discussion of possible nonanimal alternatives. Power calculations in such studies are crucial in order to use a sample size that is large enough to generate statistically useful data, whilst, at the same time, small enough to prevent the unnecessary use of animals.

Bone formation around rhBMP-2-coated implants in rabbit sinuses with or without absorbable collagen sponge grafting

PURPOSE

The purpose of this study was to evaluate bone formation around recombinant human bone morphogenetic protein (rhBMP-2)-coated implants placed with or without absorbable collagen sponge (ACS) in rabbit maxillary sinuses.

METHODS

The Schneiderian membrane was elevated and an implant was placed in 24 sinuses in 12 rabbits. The space created beneath the elevated membrane was filled with either blood (n=6) or ACS (n=6). In the rabbits in which this space was filled with blood, rhBMP-2-coated and non-coated implants were alternately placed on different sides. The resulting groups were referred to as the BC and BN groups, respectively. The AC and AN groups were produced in ACS-grafted rabbits in the same manner. Radiographic and histomorphometric analyses were performed after eight weeks of healing.

RESULTS

In micro-computed tomography analysis, the total augmented volume and new bone volume were significantly greater in the ACS-grafted sinuses than in the blood-filled sinuses (P<0.05). The histometric analysis showed that the areas of new bone and bone-to-implant contact were significantly larger in the AC group than in the AN group (P<0.05). In contrast, none of the parameters differed significantly between the BC and BN groups.

CONCLUSIONS

The results of this pilot study indicate that the insertion of ACS after elevating the Schneiderian membrane, simultaneously with implant placement, can significantly increase the volume of the augmentation. However, in the present study, the rhBMP-2 coating exhibited limited effectiveness in enhancing the quantity and quality of regenerated bone.

Bone Regeneration from PLGA Micro-Nanoparticles

Poly-lactic-co-glycolic acid (PLGA) is one of the most widely used synthetic polymers for development of delivery systems for drugs and therapeutic biomolecules and as component of tissue engineering applications. Its properties and versatility allow it to be a reference polymer in manufacturing of nano- and microparticles to encapsulate and deliver a wide variety of hydrophobic and hydrophilic molecules. It additionally facilitates and extends its use to encapsulate biomolecules such as proteins or nucleic acids that can be released in a controlled way. This review focuses on the use of nano/microparticles of PLGA as a delivery system of one of the most commonly used growth factors in bone tissue engineering, the bone morphogenetic protein 2 (BMP2). Thus, all the needed requirements to reach a controlled delivery of BMP2 using PLGA particles as a main component have been examined. The problems and solutions for the adequate development of this system with a great potential in cell differentiation and proliferation processes under a bone regenerative point of view are discussed.

A high concentration of recombinant human bone morphogenetic protein-2 induces low-efficacy bone regeneration in sinus augmentation: a histomorphometric analysis in rabbits

OBJECTIVES

The aim of the study was to elucidate the efficacy of bone regeneration at the early stage of healing in rabbit sinuses grafted with a biphasic calcium phosphate (BCP) carrier soaked in a high concentration of recombinant human bone morphogenetic protein-2 (rhBMP-2).

MATERIALS AND METHODS

Both maxillary sinuses of eight male rabbits were used. The sinus on one side (assigned randomly) was grafted with BCP loaded with rhBMP-2 (1.5 mg/ml; test group) using a soaking method, while the other was grafted with saline-soaked BCP (control group). After a 2-week healing period, the sinuses were analyzed by micro-computed tomography and histomorphometry.

RESULTS

The total augmented area and soft tissue space were significantly larger in the test group than in the control group, whereas the opposite was true for the area of residual material and newly formed bone. Most of the new bone in the test group was localized to the Schneiderian membrane (SM), while very little bone formation was observed in the window and center regions of the sinus. New bone was distributed evenly in the control group sinuses.

CONCLUSION

Within the limitations of this study, it appeared that application of a high concentration of rhBMP-2 soaked onto a BCP carrier inhibited bone regeneration from the pristine bone and increased soft tissue swelling and inflammatory response at the early healing stage of sinus augmentation, although osteoinductive potential was found along the SM.

Polyhedral microcrystals encapsulating bone morphogenetic protein 2 improve healing in the alveolar ridge

Atelocollagen sponges incorporating polyhedra encapsulating bone morphogenetic protein 2 (BMP-2) were implanted into lateral bone defects in the mandible. Half of the bone defects on the left side were treated with atelocollagen sponges containing 1.8 × 10(7) BMP-2 polyhedra, and half were treated with sponges containing 3.6 × 10(6) BMP-2 polyhedra. As controls, we treated the right-side bone defects in each animal with an atelocollagen sponge containing 5 µg of recombinant human BMP-2 (rhBMP-2) or 1.8 × 10(7) empty polyhedral. After a healing period of six months, whole mandibles were removed for micro-computed tomography (CT) and histological analyses. Micro-CT images showed that more bone had formed at all experimental sites than at control sites. However, the density of the new bone was not significantly higher at sites with an atelocollagen sponge containing BMP-2 polyhedra than at sites with an atelocollagen sponge containing rhBMP-2 or empty polyhedra. Histological examination confirmed that the BMP-2 polyhedra almost entirely replaced the atelocollagen sponges and connected the original bone with the regenerated bone. These results show that the BMP-2 delivery system facilitates the regeneration of new bone in the mandibular alveolar bone ridge and has an advance in the technology of bone regeneration for implant site development.

Pre-clinical evaluation of the osteogenic potential of bone morphogenetic protein-2 loaded onto a particulate porcine bone biomaterial

AIM

The objective of study was to determine the osteogenic potential of bone morphogenetic protein-2 (BMP-2) loaded onto a particulate porcine bone mineral (PBM) biomaterial using a sinus augmentation model.

METHODS

Release kinetics of BMP-2/PBM was determined in vitro. Eight rabbits received BMP-2/PBM or PBM alone into contra-lateral sinus sites. The animals were killed following a 2-week healing interval for micro-CT and histometrical analysis.

RESULTS

Approximately 40% of the BMP-2 was released from PBM over the first 3 days in vitro; release maintained at a reduced level through day 21. In vivo, total augmented implant volume did not differ significantly between treatments. However, local bone formation was enhanced in the BMP-2/PBM group compared with PBM control (10.5% versus 6.6%; p = 0.03), specifically in the central aspect of the PBM implant (14.2% versus 5.5%; p < 0.01) and adjoining the Schneiderian membrane (11.9% versus 5.0%; p < 0.05). There were no significant overall differences in residual biomaterial and fibrovascular tissue.

CONCLUSION

Bone morphogenetic protein-2 enhanced local bone formation in the rabbit maxillary sinus model following implantation using a PBM carrier.

Sequential healing of the elevated sinus floor after applying autologous bone grafting: an experimental study in minipigs

AIM

To describe the sequential healing after elevation of the maxillary sinus mucosa applying the lateral access technique with the use of autogenous bone grafting without membrane to occlude the osteotomy access.

MATERIAL AND METHODS

Immediately after the elevation of the maxillary sinus Schneiderian membrane, applying the lateral access technique in 10 minipigs, autologous bone was harvested from the lateral aspect of the mandibular molar region and ground into particles with a bone mill. The space under the Schneiderian membrane was filled with this graft. No membranes were placed onto the access osteotomy. The healing was evaluated after 15, 30, 90 and 180 days. Paraffin sections were prepared and analyzed histologically.

RESULTS

After 15 days of healing, the elevated area was mainly filled with provisional matrix, newly formed bone and some remnants of bone chips, and appeared reduced in volume compared with that at the time of surgery. After 30 days of healing, further shrinkage of the height of the elevated space was found, with similar percentages of the different tissue components. After 90 and 180 days, the area underneath the Schneiderian membrane appeared reduced in volume and condensed toward the base of the sinus. The bone tissues appeared to be more mature, both for the mineralized and the non-mineralized portions, while connective tissue occupied 20% of the space, most likely related to the lack of the use of a membrane occluding the access at the time of surgery.

CONCLUSIONS

Suboptimal healing outcomes with respect to augmentation of the space under the sinus floor membrane were documented when autologous bone chips were used as a filler and no membrane was applied to cover the access.

Low-dose recombinant human bone morphogenetic protein-2 to enhance the osteogenic potential of the Schneiderian membrane in the early healing phase: in vitro and in vivo studies

PURPOSE

The objectives of this study were to confirm the osteogenic potential of the Schneiderian membrane and to elucidate the early healing pattern of low-dose recombinant human bone morphogenetic protein-2 (rhBMP-2)-coated biphasic calcium phosphate (BCP).

MATERIALS AND METHODS

The osteogenic potential of the Schneiderian membrane and enhancement by rhBMP-2 were evaluated by in vitro analysis. RhBMP-2-coated BCP (experimental group) and BCP soaked with saline (control group) were applied to the maxillary sinus in rabbits. After 2 weeks, micro-computed tomographic and histometric analyses were performed.

RESULTS

Enhanced osteogenic potential was found when cells from the Schneiderian membrane were treated with rhBMP-2. Micro-computed tomographic analysis showed that the total augmented volume was significantly larger in the experimental group. Different healing patterns were observed in 3 regions, although the area of new bone did not differ significantly. Although more newly formed bone appeared, particularly along the Schneiderian membrane in the experimental group, the difference was not statistically significant.

CONCLUSIONS

RhBMP-2 enhanced the osteogenic potential of the Schneiderian membrane in vitro. However, low-dose rhBMP-2-coated BCP failed to exert a statistically significant effect in vivo, although it appeared to be effective in sinus augmentation specifically for the volumetric increase in the early phase.

Sinus augmentation using BMP-2 in a bovine hydroxyapatite/collagen carrier in dogs

AIM

The objective of this study was to determine the efficacy of bone morphogenetic protein 2 (BMP-2) in a bovine hydroxyapatite/collagen (BHC) carrier to augment bone formation in a canine nasal sinus model.

METHODS

Eight mongrel dogs, approximately 12 months old and 30 kg in weight were used. Following preparation of bilateral sinus access windows, BHC alone (control) or loaded with E. coli-derived BMP-2 at 0.1 mg/ml was implanted in four animals, and BHC loaded with E. coli-derived BMP-2 at 0.5 and 1.5 mg/ml was implanted in four animals. The animals were euthanized at 20 weeks when block sections were obtained for micro-computed tomography and histometric analyses.

RESULTS

Total augmented volumes did not differ significantly between groups. Histometric analysis showed significantly enhanced bone formation for the BMP-2 groups compared with control.

CONCLUSION

BMP-2 in a BHC carrier, even at the low 0.1-mg/ml concentration, induces osteogenic activity, enhancing local bone formation in a canine sinus model.

Alveolar ridge and maxillary sinus augmentation using rhBMP-2: a systematic review

PURPOSE

The aim of this systematic review was to evaluate clinical and safety data for recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier when used for alveolar ridge/maxillary sinus augmentation in humans.

MATERIALS AND METHODS

Clinical studies/case series published 1980 through June 2012 using rhBMP-2/ACS were searched. Studies meeting the following criteria were considered eligible for inclusion: >10 subjects at baseline and maxillary sinus or alveolar ridge augmentation not concomitant with implant placement.

RESULTS

Seven of 69 publications were eligible for review. rhBMP-2/ACS yielded clinically meaningful bone formation for maxillary sinus augmentation that would allow placement of regular dental implants without consistent differences between rhBMP-2 concentrations. Nevertheless, the statistical analysis showed that sinus augmentation following autogenous bone graft was significantly greater (mean bone height: 1.6 mm, 95% CI: 0.5-2.7 mm) than for rhBMP-2/ACS (rhBMP-2 at 1.5 mg/mL). In extraction sockets, rhBMP-2/ACS maintained alveolar ridge height while enhancing alveolar ridge width. Safety reports did not represent concerns for the proposed indications.

CONCLUSIONS

rhBMP-2/ACS appears a promising alternative to autogenous bone grafts for alveolar ridge/maxillary sinus augmentation; dose and carrier optimization may expand its efficacy, use, and clinical application.