Effects of rhBMP-2-loaded hydroxyapatite granules/beta-tricalcium phosphate hydrogel (HA/ß-TCP/hydrogel) composite on a rat model of caudal intervertebral fusion.

The effects and inflammation-related side effects of bone morphogenetic protein (BMP)-2 on posterior lumbar interbody fusion are controversial. One of the potential causes for the inconsistent results is the uncontrolled release of BMP-2 from the collagen carrier. Therefore, BMP delivery systems that support effective bone regeneration while attenuating the side effects are strongly sought for. We developed NOVOSIS putty (NP), a novel composite material of hydroxyapatite (HA), beta-tricalcium phosphate (ß-TCP)/hydrogel, and BMP-2, which can sustainably release BMP-2 over 2 weeks. This study was aimed at comparing the effects and side effects of NP and collagen sponge (CS) containing BMP-2 using a rat caudal intervertebral fusion model. The fusion rates of NP with low and high doses of BMP-2 were significantly higher than those of an iliac bone (IB) graft, but those of CS with low and high doses of BMP-2 were not different from those of the IB graft. Furthermore, the incidences of ectopic bone formation and soft tissue swelling were significantly lower in the NP group than in the CS group. The HA/ß-TCP/hydrogel carrier enabled superior bone induction with low-dose BMP-2 and decreased the incidence of side effects caused by high-dose BMP-2 vis-à-vis the collagen carrier.

Effect of nano-hydroxyapatite and ozone on approximal initial caries: a randomized clinical trial.

The aim of the study was to assess the efficacy of three methods of enamel remineralization on initial approximal caries: (1) a nano-hydroxyapatite gel, (2) gaseous ozone therapy, (3) combination of a nano-hydroxyapatite gel and ozone. Patients (n = 92, age 20-30 years) with initial approximal enamel lesions on premolar and molar teeth (n = 546) were randomly allocated to three groups subjected to a 6-months treatment: Group I: domestic nano-hydroxyapatite remineralizing gel, group II: in-office ozone therapy, group III: both domestic remineralizing gel and ozone therapy. Caries lesions were assessed on bitewing radiographs at baseline, after 1 year and after 2 years. At one-year follow-up, the smallest rate of lesions with remineralisation (36.5%) was found in group I, and the highest (69.3%)-in group III. In group III a significant remineralisation was noticed in after 1 year and then a demineralisation after 2 years. Thus nano-hydroxyapatite gel and ozone therapy exert some capacities to remineralize approximal enamel and dentine subsurface lesions of premolar and molar teeth. Moreover, the combination of both methods produces the best effect compared to nano-hydroxyapatite or ozone therapy applied alone. However, the treatment should be continued for a long time in order to achieve nonrestorative recovery of caries.

Effects of Combined Magnetic Fields Treatment and Nano-Hydroxyapatite Coating on Porous Biphasic Calcium Phosphate Bone Graft in Rabbit Spinal Fusion Model.

STUDY DESIGN: An animal experimental study was designed to investigate the efficacy of combined magnetic fields (CMF) treatment and nano-hydroxyapatite (HA) coating in the biphasic calcium phosphate (BCP) graft in posterolateral lumbar fusion. OBJECTIVE: To evaluate the effects of CMF treatment and nano-HA/BCP and their combination effect in posterolateral lumbar fusion. SUMMARY OF BACKGROUND DATA: Enhancement of artificial bone graft bioeffects could improve spinal fusion outcomes. The bone graft integration is vital in spinal fusion, nano-HA coating, and CMF treatment were reported as effective methods to improve bone graft integration. METHODS: A bilateral transverse process fusion model was performed on 32 rabbits. The CMF treatment was performed for 30 minutes per day postoperation. The fusion rate, new bone formation, artificial bone graft-autologous bone fusion interface in x-ray and scanning electron microscopy, biomechanics property of fusion rate, histological fusion condition, artificial bone residual rate, and immunohistochemistry assessment of bone morphogenetic protein 2 (BMP-2) and Transforming growth factor beta 1 (TGF-ß1) expression were observed at 9th week after surgery. RESULTS: CMF treatment and nano-HA coating increased the fusion rate, adjusted optical density index, intensity of binding of artificial and autologous bone, bone growth rate, and bending stiffness. CMF treatment also significantly increased BMP-2 and TGF-ß1 expression in fusion region while nano-HA coating significantly decreased artificial bone residual rate. CONCLUSION: Our findings suggest that porous nano-HA/BCP graft could significantly improve spine fusion outcome with excellent bioactivity, biocompatibility and degradability and CMF treatment could significantly improve spine fusion outcome by improving bioactivity and biocompatibility of artificial bone graft in rabbit. Combination of CMF treatment with nano-HA/BCP graft could significantly increase posterolateral lumbar fusion rate in rabbit, which would be a potential strategy for spine fusion preclinical study. LEVEL OF EVIDENCE: N/A.

Bone preservation in dehiscence-type defects using composite biphasic calcium sulfate plus biphasic hydroxyapatite/ß-tricalcium phosphate graft: a histomorphometric case series in canine mandible.

OBJECTIVES: To examine bone formation in dehiscence defects using biphasic hydroxyapatite/ß-tricalcium phosphate plus biphasic calcium sulfate (BCP/BCS). MATERIAL: After extractions, 24 mandibular buccal dehiscence defects (3 × 3 mm) were treated with BCP/BCS (E), membrane (MC), or control (NC). Histology and histomorphometric analysis were performed. RESULTS: After 6 weeks, bone formation was noticeable in most sites. In subsequent phases, the woven bone was gradually remodeled into lamellar bone and marrow. Vertical new bone height in the E and MC groups (1.06 and 0.85 mm.) was substantially greater than that in the NC group (-0.28 mm). For all groups, there was an overall increase in the height of the newly formed bone through the observation. At week 12, the vertical bone height was 1.95, 2.07, and 0.29 mm, respectively. The mean new bone area in the E and MC groups was much greater than that in the NC group (2.85, 2.80, and -0.20 mm, respectively). Percent new bone in all 3 groups was similar (36.25%, 34.84%, and 28.34%, respectively). CONCLUSIONS: This study demonstrates the efficacy of BCP/BCS graft for bone augmentation in dehiscence-type extraction socket defect.

Regenerative wound healing in acute degree III mandibular defects in dogs.

OBJECTIVE: To evaluate the healing events in degree III furcation defects in dogs following the application of the combination of an enamel matrix derivative with a biphasic calcium phosphate (Emdogain Plus). METHOD AND MATERIALS: Seventeen degree III furcation defects, 5 mm high and 4 mm wide, were created in 9 dogs. In both groups, the defects were conditioned with EDTA. One defect was treated with Emdogain Plus (n = 9), while the contralateral defect serving as control remained empty (n = 8). The defects in both groups were fully covered by coronally repositioned flaps. After 5 months of healing, histologic and histometric analysis was preformed. RESULTS: A significant amount of new attachment and bone formation was observed in both control and test specimens. However, in a number of control specimens, ankylosis was also observed. In the control and test groups, respectively, the mean new cementum length was 10.8 ± 2.1 mm and 8.6 ± 3.2 mm; the mean periodontal ligament length was 7.6 ± 3.8 mm and 8.1 ± 4.0 mm. The mean new bone height was 4.4 ± 1.3 mm and 4.3 ± 1.6 mm in the control and test groups, respectively. No statistical differences were found between the two groups in terms of amount of cementum, periodontal ligament, and alveolar bone regeneration. CONCLUSION: The present study failed to show higher amounts of newly formed cementum and bone following treatment of acute degree III mandibular furcation defects following use of Emdogain Plus compared with a coronally advanced flap. Emdogain Plus seems to have a protective role against ankylosis in this type of defect.

Four-year results following treatment of intrabony periodontal defects with an enamel matrix derivative alone or combined with a biphasic calcium phosphate.

The aim of this study was to evaluate the 4-year clinical outcomes following regenerative surgery in intrabony defects with either EMD + BCP or EMD. Twenty-four patients with advanced chronic periodontitis, displaying one-, two-, or three-walled intrabony defect with a probing depth of at least 6 mm, were randomly treated with either EMD + BCP (test) or EMD alone (control). The following clinical parameters were evaluated at baseline, at 1 year and at 4 years after regenerative surgery: plaque index, gingival index, bleeding on probing, probing depth, gingival recession, and clinical attachment level (CAL). The primary outcome variable was CAL. No differences in any of the investigated parameters were observed at baseline between the two groups. The test group demonstrated a mean CAL change from from 10.8 ± 1.6 mm to 7.4 ± 1.6 mm (p < 0.001) and to 7.6 ± 1.7 mm (p < 0.001) at 1 and 4 years, respectively. In the control group, mean CAL changed from 10.4 ± 1.3 at baseline to 6.9 ± 1.0 mm (p < 0.001) at 1 year and 7.2 ± 1.2 mm (p < 0.001) at 4 years. At 4 years, two defects in the test group and three defects in the control group have lost 1 mm of the CAL gained at 1 year. Compared to baseline, at 4 years, a CAL gain of ≥3 mm was measured in 67% of the defects (i.e., in 8 out of 12) in the test group and in 75% of the defects (i.e., in 9 out of 12) in the control group. There were no statistically significant differences in any of the investigated parameters at 1 and at 4 years between the two groups. Within their limits, the present results indicate that: (a) the clinical improvements obtained with both treatments can be maintained over a period of 4 years, and (b) in two- and three-walled intrabony defects, the addition of BCP did not additionally improve the outcomes obtained with EMD alone. In two- and three-walled intrabony defects, the combination of EMD + BCP did not show any advantage over the use of EMD alone.

Healing of acute alveolar bone dehiscence following treatment with porous biphasic calcium phosphate in beagle dogs.

The purpose of the present study was to evaluate histologically in beagle dogs the healing in acute dehiscence type defects following treatment with open flap debridement (OFD) with or without porous biphasic calcium phosphate (PBCP). Alveolar bone dehiscence defects were surgically created bilaterally at the labial aspects of maxillary third incisors in 12 beagle dogs. After root conditioning with ethylenediaminetetraacetate, PBCP was filled in the defects and the contralaterals were cured with OFD. Two fluorochrome labelings were administered at the 7th and 11th weeks, respectively. Four dogs were killed at the 12, 16, and 24 weeks, respectively. Histological observations were processed through microcomputed tomographic imaging, fluorescence microscope, and light microscopy. The formation of new regenerated tissues was assessed histomorphometrically. The results revealed the healing after treatments with PBCP evidenced a new attachment apparatus and that with OFD supported periodontal repair. In PBCP groups, the amount of new bone varied from 1.15 to 3.86 mm (23-77.2% of the original defect size), while only 0.3 to 1.04 mm (6-20.8%) in OFD group. The amount of new cementum in PBCP varied from 1.18 to 4.16 mm (23.6-82.3%), while only 0.67 to 1.15 mm (13.4-23%) in OFD group. The amount of periodontal ligament in PBCP varied from 1.03 to 4.12 mm (20.6-82.4%), while only 0 to 0.93 mm (0-18.6%) in OFD group. There was significantly more regenerated tissue in PBCP groups compared to OFD procedures (p < 0.01). The present results indicate that PBCP may enhance periodontal regeneration in acute-type labial dehiscence defects.

Guiding bone formation in a critical-sized defect and assessments.

PURPOSE: Development of alternatives to autologous bone has been served by many hypotheses and developments. Favorable properties of synthetic materials used currently in bone grafting support tissue differentiation without shielding capacity for integrated modeling. Ideally, new materials provide tissue compatibility and minimize patient morbidity and are attractive because of potential for in situ delivery, isothermal polymerization, porous structure, and nontoxic chemistry. For application in cranial bone, ability for materials to be laid adjacent to brain and offer postsurgical protection without neural risk is a critical asset. METHODS: Kryptonite Bone Cement (KBC) meets the property criteria for cranial bone repair with regard to adhesive, conductive, and biologic transparency and US Food and Drug Administration approval for cranial bone void repair. To better delineate the morphology effective in cranial bone repair, a comparison was made between KBC and BoneSource, another material approved for the same indication. After Institutional Animal Care and Use Committee approval, the study assessed 24 rabbits, each with 2 separate cranial implants, to evaluate integration and absorption of the biomaterial at defined time points of 12, 18, 24, and 36 weeks. RESULTS: The 36-week assessment demonstrated near-complete resorption/integration of the BoneSource graft material. Bone was present within the biomaterial as well as independent of contact. The KBC was similarly integrated throughout the mass of the material, and new bone was in contact with the grafting material and also seen as separate islands of new bone. The bone demonstrated lamellar bone architecture with clear trabecular morphology. At higher magnification, the bone architecture can be clearly delineated, and comparison between the graft fillers is not obvious relative to the bone that has formed. Despite microscopic similarities, the most striking difference was maintenance of scaffold anatomy during bone regeneration. CONCLUSIONS: Kryptonite Bone Cement meets the criteria described in the introduction; properties of biologic transparency, osteoconductivity, and ergonomic utility offer other potential uses in bone repair. Key tenets of bone tissue regeneration observed in this analysis included adequate cell differentiation and tissue support. Bone that formed demonstrated lamellar rather than woven bone to suggest response to loading strain rather than merely biochemical precipitation. Over the 36-week study, the graft showed progressive bioabsorbable potential with calibrated replacement.

Histological evaluation on bone regeneration of dental implant placement sites grafted with a self-setting alpha-tricalcium phosphate cement.

This study aimed to evaluate the histological characteristics of the new bone formed at dental implant placement sites concomitantly grafted with a self-setting tricalcium phosphate cement (BIOPEX-R). Standardized defects were created adjacent to the implants in maxillae of 4-week-old male Wistar rats, and were concomitantly filled with BIOPEX-R. Osteogenesis was examined in two sites of extreme clinical relevance: (1) the BIOPEX-R-grafted surface corresponding to the previous alveolar ridge (alveolar ridge area), and (2) the interface between the grafting material and implants (interface area). At the alveolar ridge area, many tartrate-resistant acid phosphatase (TRAPase)-reactive osteoclasts had accumulated on the BIOPEX-R surface and were shown to migrate toward the implant. After that, alkaline phosphatase (ALPase)-positive osteoblasts deposited new bone matrix, demonstrating their coupling with osteoclasts. On the other hand, the interface area showed several osteoclasts initially invading the narrow gap between the implant and graft material. Again, ALPase-positive osteoblasts were shown to couple with osteoclasts, having deposited new bone matrix after bone resorption. Transmission electron microscopic observations revealed direct contact between the implant and the new bone at the interface area, although few thin cells could still be identified. At both the alveolar ridge and the interface areas, newly formed bone resembled compact bone histologically. Also, concentrations of Ca, P, and Mg were much alike with those of the preexistent cortical bone. In summary, when dental implant placement and grafting with BIOPEX-R are done concomitantly, the result is a new bone that resembles compact bone, an ideal achievement in reconstructive procedures for dental implantology.

The use of osteoconductive bone graft substitutes in orthopaedic trauma.

Several bone graft substitutes are now available for use in augmenting bone healing following trauma. Many of these products are osteoconductive and are indicated for filling bone defects in conjunction with standard methods of internal and external fixation. Osteoconduction refers to a process in which the three-dimensional structure of a substance is conducive for the ongrowth and/or ingrowth of newly formed bone. Currently used bone graft substitutes that primarily offer osteoconductive properties include coralline hydroxyapatite, collagen-based matrices, calcium phosphate, calcium sulfate, and tricalcium phosphate. These products vary considerably in chemical composition, structural strength, and resorption or remodeling rates. Understanding these differences is important in selecting a bone graft substitute with the properties desired for a specific clinical situation. The limited number of clinical studies and lack of direct-comparison studies between these products require the surgeon to fully understand the properties of each product when choosing a bone graft substitute.

The role of the osteoconductive scaffold in synthetic bone graft.

Autogenous bone is regarded as the gold standard for bone graft materials as it provides 3 elements necessary to generate and maintain bone: scaffolding for osteoconduction, growth factors for osteoinduction, and progenitor cells for osteogenesis. Allograft is more limited than autograft in these essential elements and yields more variable clinical results. Composite synthetic grafts offer an alternative that can potentially unite the 3 salient bone-forming properties in more controlled and effective combinations than can be obtained in many clinical situations, without the disadvantages found with autograft. This article examines the underemphasized but crucial role of the osteoconductive scaffold in the composite synthetic bone graft.

Synthetic bone graft substitutes.

Replacement of extensive local bone loss is a significant clinical challenge. There are a variety of techniques available to the surgeon to manage this problem, each with their own advantages and disadvantages. It is well known that there is morbidity associated with harvesting of autogenous bone graft and limitations in the quantity of bone available. Alternatively allografts have been reported to have a significant incidence of postoperative infection and fracture as well as the potential risk of disease transmission. During the past 30 years a variety of synthetic bone graft substitutes has been developed with the aim to minimize these complications. The benefits of synthetic grafts include availability, sterility and reduced morbidity. The present article examines the relevance of synthetic bone graft substitutes, their mechanical properties and clinical application.

[In vitro assessment of combining osteogenic cells with macroporous calcium-phosphate ceramics]. / Etude in vitro de l'association de cellules ostéogènes avec une céramique en phosphate de calcium macroporeuse.

PURPOSE OF THE STUDY: Bone grafts or bone substitutes are required to fill bone defects resulting from trauma or surgical resection of tumors. Calcium-phosphate ceramics are synthetic bone substitutes which promote new bone formation by osteoconduction. These ceramics possess osteoconductive properties but have no intrinsic osteoinductive capacity. They are unable to induce new bone formation in extraossesous sites. One solution to develop bone substitutes with osteogenic properties would be to associate biomaterials with osteoprogenitors. MATERIALS AND METHODS: We studied the in vitro osteogenic potential of human bone-marrow cells cultured on macroporous calcium phosphate (CaP) ceramic, examining stromal cell proliferation and differentiation. Osteogenic differentiation was evaluated in terms of alkaline phosphatase activity and immunological characterization of the extracellular fibrillar matrix formed by these cells. The specimens were examined by scanning and transmission electron microscopy. RESULTS: Human bone-marrow cells proliferated on CaP ceramic. The proliferating bone-marrow cells expressed an osteoblastic phenotype as shown by alkaline phosphatase activity and synthesis in ceramic pores of an extracellular matrix composed of fibronectin, osteocalcin and collagen I. In addition, numerous microcrystals of apatite precipitated on the fibrillar matrix, producing a mineralized fibrillar network within the ceramic. CONCLUSION: This study demonstrates that human bone-marrow cells cultured on macroporous CaP ceramic do not lose their osteoblastic phenotype even after 21 days of culture, and that they can induce osteogenesis in a CaP ceramic in vitro. This type of new "hybrid material" appears promising for the future.

[A comparative analysis of the efficacy of different types of filling materials in the surgical elimination of tooth perforations (experimental morphological research)]. / Sravnitel'nyi analiz éffektivnosti plombirovochnykh materialov razlichnykh tipov pri khirurgicheskom ustranenii perforatsii zubov (éksperimental'no-morfologicheskoe issledovanie).

Based on the experimental morphological findings, the authors compare the efficiency of tooth perforation repair in experimental animals by surgical method using Dyract compomer, Base Line glass ionomeric cement, and Ostim-100 osteoplastic material. The data indicate a high efficiency of this method. Base Line material is preferable for filling the perforation in dental wall, as it reliably performed the isolating function under experimental conditions.

Effect of in situ plaque mineral supplementation on the state of saturation of plaque fluid during sugar-induced acidogenesis.

Dental plaque fluid is normally supersaturated with respect to enamel mineral but this may change to a state of undersaturation when plaque pH falls following sugar exposure, placing the adjacent enamel at risk of caries. We have determined the saturation status of the fluid in both resting and fermenting plaque following mineral supplementation. Eleven subjects abstained from oral hygiene and rinsed their mouth 3 times/d for 3 d with a placebo solution or with test solutions designed to enrich plaque with hydroxyapatite or fluorhydroxyapatite. On the morning of day 4, plaque samples were collected before and after exposure to 10% sucrose. Compared to the placebo, use of the test rinses resulted in significantly higher concentrations of Ca, P and F in plaque residue. In plaque fluid, higher post-sucrose Ca2+ free concentrations and saturation levels with respect to enamel mineral and fluorapatite were found after use of the hydroxyapatite rinse compared to the placebo, effects that probably resulted from the release of cell-bound Ca2+ as well as from the dissolution of apatite. Thus, some evidence was obtained that the test mouthrinses can counteract the fall in saturation level found when plaque is exposed briefly to sucrose. Potential long-term benefits of the test mouthrinses deserve further study.

Hydroxyapatite clay used to fill the gap between implant and bone.

A clay containing hydroxyapatite (HA) was developed for use as a filling material between an uncemented implant and bone. It consists of 55% HA granules greater than 0.1 mm in size with a homogeneous pore distribution and a porosity of 35% to 48% in a saline solution of sodium alginate (6%). Ti-6A1-4V alloy rods with smooth surfaces were implanted into the distal medullary canal of one osteotomised tibia of 32 Japanese white rabbits. Sixteen rods were inserted with HA clay and 16 without the clay to act as a control group. Six of each group were killed at one week and ten at 12 weeks postoperatively. The pull-out strength of the implants with HA clay was significantly greater at 12 weeks (p < 0.05), as was the percentage of the area of the new bone (p < 0.05). The study suggests that HA clay has an osteoconductive property, allowing adequate bone fixation across a gap at an early stage. The use of HA clay to enhance the early stability of uncemented components may help to improve the functional outcome of total joint arthroplasty.

Chemistry and biological behavior of samarium-153 and rhenium-186-labeled hydroxyapatite particles: potential radiopharmaceuticals for radiation synovectomy.

Hydroxyapatite (HA), a natural constituent of bone, was studied as a particulate carrier for beta-emitting radionuclides in radiation synovectomy. Particles were radiolabeled with 153Sm or 186Re and their in vivo safety was investigated following intra-articular injection into knees of normal rabbits and rabbits with antigen-induced arthritis (AIA). Radiolabeling efficiency was greater than 95%; in vitro studies showed minimal (< or = 1%) loss of activity from particles over a 6-day period with 153Sm-labeled HA and about 5% loss of activity over a 5-day period with 186Re-labeled HA. The total cumulative extra-articular leakage of 153Sm over 6 days was 0.28% in normal rabbits and 0.09% in AIA rabbits. Leakage of 186Re from the joint was 3.05% over a 4-day period with 80% of extra-articular activity found in the urine. Histopathological evaluation of treated knees showed that HA particles are distributed throughout the synovium, embedded in the synovial fat pad. The ease and efficiency with which this HA carrier is labeled, coupled with observed extremely low leakage rates from the joint, make radiolabeled HA particles an attractive candidate as a radiation synovectomy agent for evaluation in rheumatoid arthritis patients.

Facial skeletal augmentation using hydroxyapatite cement.

This study investigates the use of a new calcium phosphate cement, which sets to solid, microporous hydroxyapatite, for facial bone augmentation. In six dogs, the supraorbital ridges were augmented bilaterally with this hydroxyapatite cement. On one side, the hydroxyapatite cement was placed directly onto the bone within a subperiosteal pocket. On the opposite side, the cement was contained within a collagen membrane tubule and then inserted into a subperiosteal pocket. The use of collagen tubules facilitated easy, precise placement of the cement. All implants maintained their original augmented height throughout the duration of the study. They were well tolerated without extrusion or migration, and there was no significant sustained inflammatory response. Histologic studies, performed at 3, 6, and 9 months revealed that when the cement was placed directly onto bone, progressive replacement of the implant by bone (osseointegration of the hydroxyapatite with the underlying bone) without a loss of volume was observed. In contrast, when the cement-collagen tubule combination was inserted, primarily a fibrous union was noted. Despite such fibrous union, the hydroxyapatite-collagen implant solidly bonded to the underlying bone, and no implant resorption was observed. Hydroxyapatite cement can be used successfully for the experimental augmentation of the craniofacial skeleton and may be applicable for such uses in humans.

[The effect of hydroxylapatite on the experimental healing of the tooth socket]. / Vliianie gidroksilapatita na zazhivlenie lunki zuba v éksperimente.

Synthetic hydroxylapatite, a drug made in this country, enhanced reparative osteogenesis if introduced in the dental well of a white rat. The regenerate represented solid bone structure in 4 months after tooth removal.