Phosphate Graft Research Articles

Effect of sex-hormone levels, sex, body mass index and other host factors on human craniofacial bone regeneration with bioactive tricalcium phosphate grafts

Little is known regarding the associations between sex-hormone levels, sex, body mass index (BMI), age, other host factors and biomaterial stimulated bone regeneration in the human craniofacial skeleton. The aim of this study was to elucidate the associations between these factors and bone formation after sinus floor augmentation procedures (SFA) utilizing a bioactive tricalcium phosphate (TCP) bone grafting material. We conducted a prospective study in a human population in which 60 male and 60 female participants underwent SFA and dental implant placement using a staged approach. BMI as well as levels of serum estradiol (E2), total testosterone (TT), and the free androgen index (FAI) were measured by radioimmunoassay and electrochemoluminescent-immunoassay. At implant placement, 6 months after SFA, bone biopsy specimens were harvested for hard tissue histology, the amount of bone formation was evaluated by histomorphometry and immunohistochemical analysis of osteogenic marker expression. The Wilcoxon rank-sum U test, Spearman correlations and linear regression analysis were used to explore the association between bone formation and BMI, hormonal and other host factors. BMI and log E2 were significantly positively associated with bone formation in male individuals (p<0.05). Histomorphometry revealed trends toward greater bone formation and osteogenic marker expression with non-smokers compared to smokers. In male patients, higher E2 levels and higher BMI enhanced TCP stimulated craniofacial i.e. intramembranous bone repair.

Osteoclast differentiation from human blood precursors on biomimetic calcium-phosphate substrates.

The novelty of the paper is the differentiation of human blood-derived osteoclast precursors, instead of mouse-derived macrophages as used in most studies, directly on biomimetic micro-nano structured HA-based surfaces, as triggered by osteoblast-produced factors (RANKL/OPG), and influenced by chemistry and topography of the substrate(s). Biomimetic HA-surfaces, like those obtained in calcium phosphate cements, are very different from the conventional calcium phosphate ceramics, both in terms of topography and ion exchange. The role of these factors in modulating precursors' differentiation and activity is analysed. The system is closely reproducing the physiological process of attachment of host cells and further maturation to osteoclasts toward resorption of the substrate, which occurs in vivo after filling bone defects with the calcium phosphate grafts.

Beta-tricalcium phosphate (beta-TCP) graft combined with bone marrow stromal cells (MSCs) for posterolateral spine fusion.

Macaque lumber posterolateral spine fusion (PLF) was performed by using beta-TCP graft combined with bone marrow derived stromal cells (MSCs), to evaluate whether a beta-TCP/MSCs hybrid can be used for PLF instead of autogenous bone graft. Nine crab-eating macaque underwent bilateral PLF at L4-L5. The implants were divided into three groups: 1) beta-TCP/MSCs hybrid, 2) autogenous bone, and 3) beta-TCP. Six monkeys were sacrified at 12 weeks and three monkeys were sacrificed at 24 weeks after implantation. Manual palpation, radiography, micro computed tomography, peripheral quantitative computed tomography (pQCT), and histology were used to assess bone formation. Manual palpation and X-ray showed that 83.3% of hybrid groups and 66.7% of autogenous groups achieved solid spine fusion, whereas none of other groups fused. Histological analysis showed that all of the hybrid groups achieved massive bone formation. Bone mineral density (BMD) evaluated with pQCT in the hybrid groups increased by additional new bone. Beta-TCP/MSCs hybrid can be used for PLF instead of autogenous bone graft. Thus it can be hypothesized that the monkey PLF can simulate human PLF.

Temperature Influence on the Calcium Phosphate Coatings by Chemical Method

The increasing interest in the use of brushite and monetite as resorbable calcium phosphate cements or graft materials is related to the fact of these phases being metastable under physiological environment, with higher solubility than hydroxyapatite phase. In this study, X-ray diffraction (XRD) and scanning electron microscopy with field emission gun (FEG-SEM) analyses were performed in order to assess the temperature influence on the production of calcium phosphate coatings by a chemical deposition method. Titanium substrates were successfully coated with brushite and monetite by a chemical deposition method and a brushite-monetite transformation was assessed with the increasing temperature. Brushite deposition was kinetically favored at low temperatures, whereas monetite was the major phase at higher temperatures.

Efficacy of β-Tricalcium Phosphate Graft into the Bone Defects after Bone-Patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction.

This prospective pilot study investigated whether grafting β-tricalcium phosphate (B-TCP) into the bone-patellar tendon-bone (BPTB)-harvesting site after anterior cruciate ligament reconstruction would accelerate bone and tendon regeneration in the grafted site. Overall, 19 patients agreed prospectively to undergo regular morphological and histological examinations of the B-TCP-grafted site. Postoperative radiographic, ultrasonographic, and magnetic resonance imaging (MRI) examinations were performed to evaluate the grafted site at 1, 3, 6, and 12 months. Postoperative knee function and donor-site morbidity were assessed at 12 months using the kneeling test. A histological examination was also performed at this time Radiographic examination and MRI showed that the grafted B-TCP was completely absorbed and remodeled into normal bone structure in the tibia and patella at 6 months postoperatively. Histological and ultrasonographic examinations of all subjects showed that the grafted B-TCP was substituted by normal bone tissue, and the patellar tendon - bone junction had regenerated at 12 months postoperatively. Clinical functional knee tests showed good recovery of the donor site. All patients could perform kneeling and knee walking on hard ground. The results of this pilot study suggest that grafting B-TCP into the BPTB-harvesting site promotes the remodeling process of the bone and patellar tendon structures. This surgical treatment would decrease an incidence of the anterior knee pain after ACLR using a BPTB autograft.

Guided bone regeneration with local zoledronic acid and titanium barrier: An experimental study.

The aim of this study was to evaluate the effects on new bone formation of autogenous blood alone or in combination with zoledronic acid (ZA), a β-tricalcium phosphate (β-TCP) graft or ZA plus a β-TCP graft placed under titanium barriers. For this purpose, eight adult male New Zealand white rabbits were used in the study, each with four titanium barriers fixed around four sets of nine holes drilled in the calvarial bones. The study included four groups, each containing 2 rabbits. In the autogenous blood (AB group), only autogeneous blood was placed under the titanium barriers. The three experimental groups were the AB+ZA group, with autogenous blood plus ZA, the AB+β-TCP group, with autogeneous blood plus a β-TCP graft, and the AB+β-TCP+ZA group, with autogeneous blood plus a β-TCP graft and ZA mixture under the titanium barriers. The animals were sacrificed after 3 months. The amounts of new bone formation identified histomorphometrically were found to be higher after 3 months than at the time of surgery in all groups. The differences between the groups were examined with histomorphometric analysis, and statistically significant differences were identified at the end of the 3 months. The bone formation rate in the AB+β-TCP+ZA group was determined to be significantly higher than that in the other groups (P<0.05). In the AB+ZA and AB+β-TCP groups, the bone formation rate was determined to be significantly higher than that in the AB group (P<0.05). No statistically significant difference in bone formation rate was observed between the AB+β-TCP and AB+ZA groups. Local ZA used with autogeneous blood and/or graft material appears to be a more effective method than the use of autogeneous blood or graft alone in bone augmentation executed with a titanium barrier.

Cellular behavior of L929 and MG-63 cells cultured on electrospun nanofibers of chitosan with different degrees of phosphorylation

Phosphate groups chemically grafted onto polymer substrates can be used as biomimetic analogs for in vitro studying of function of biomacromolecules and also as tissue substitutes in clinical conditions of organ loss. Despite this inspiration, studies correlating effect of degree of phosphate grafting of a polymer on fabrication and biological properties of polymers are lacking. In this work, N-methylene phosphonic chitosan (PC) with different degrees of phosphate contents were synthesized and the effect of phosphate grafting on electrospinning behavior of substituted polymers is investigated. In PC, higher phosphate content widened concentration range for nanofiber formation. Balance between conductivity and viscosity of solutions played a determinant role in the success of electrospinning process. Culture of L929 cells showed grafting-dependent increase in cell proliferation. On the other hand, culture of MG-63 cells showed a positive correlation between grafting degree and Alkaline Phosphatase (ALP) expression. It is concluded that improvement of cell response parameters of nanofiber scaffolds can be attained as a function of controlled degree of phosphate grafting in polymeric biomaterials with implications for bone tissue engineering applications. Such studies may also be useful to develop quantitative structure activity relationships of functional polymers.

Micro-intumescent flame retardant polyamide 6 based on cyclic phosphate grafting phenol formaldehyde

In this paper, thermoplastic phenol formaldehyde (PF) grafted cyclic neopentyl phosphate (PFCP) was synthesized by using PF and 2,2-dimethyl-1,3-propanediol phosphoryl chloride. It was characterized by Fourier transform infrared spectroscopy (FTIR), 1H and 31P nuclear magnetic resonance (NMR). Compared to PF, PFCP shows improved thermal and thermoxidative stability and allows itself to be used in polyamide 6 (PA6). A micro-intumescent flame retardant system was constructed by using cyclic neopentyl phosphate as acid source, PF as charring agent and PA6 whose decomposition products work as blowing agent. The results showed that PA6/PFCP composite is classified the UL-94V-0 rating and get a LOI value of 35.5% at 25% loading of PFCP. SEM results showed that the outside of char residues is continuous and dense, but the inside is micro-intumescent and porous. XPS analysis of char revealed that most of phosphorus remained in the char layer. All the results suggest that the mode of flame retardant's action for PA6/PFCP composites is shifted from melting away to charring protection with the content of PFCP increasing. The coherent char generated by the decomposition of PFCP contributes most to flame retardancy of PA6. Copyright (c) 2016 John Wiley & Sons, Ltd.

Real-time-guided bone regeneration around standardized critical size calvarial defects using bone marrow-derived mesenchymal stem cells and collagen membrane with and without using tricalcium phosphate: an in vivo micro-computed tomographic and histologic experiment in rats.

The aim of the present real time in vivo micro-computed tomography (µCT) and histologic experiment was to assess the efficacy of guided bone regeneration (GBR) around standardized calvarial critical size defects (CSD) using bone marrow-derived mesenchymal stem cells (BMSCs), and collagen membrane (CM) with and without tricalcium phosphate (TCP) graft material. In the calvaria of nine female Sprague-Dawley rats, full-thickness CSD (diameter 4.6 mm) were created under general anesthesia. Treatment-wise, rats were divided into three groups. In group 1, CSD was covered with a resorbable CM; in group 2, BMSCs were filled in CSD and covered with CM; and in group 3, TCP soaked in BMSCs was placed in CSD and covered with CM. All defects were closed using resorbable sutures. Bone volume and bone mineral density of newly formed bone (NFB) and remaining TCP particles and rate of new bone formation was determined at baseline, 2, 4, 6, and 10 weeks using in vivo µCT. At the 10th week, the rats were killed and calvarial segments were assessed histologically. The results showed that the hardness of NFB was similar to that of the native bone in groups 1 and 2 as compared to the NFB in group 3. Likewise, values for the modulus of elasticity were also significantly higher in group 3 compared to groups 1 and 2. This suggests that TCP when used in combination with BMSCs and without CM was unable to form bone of significant strength that could possibly provide mechanical “lock” between the natural bone and NFB. The use of BMSCs as adjuncts to conventional GBR initiated new bone formation as early as 2 weeks of treatment compared to when GBR is attempted without adjunct BMSC therapy.

Use of β-tricalcium phosphate grafts for Airway reconstruction in rabbits: A pilot study

To assess the safety and feasibility of using β-tricalcium phosphate grafts in airway reconstruction in rabbits. Interventional animal study. Ten New Zealand White rabbits underwent division of the anterior cricoid cartilage with interposition of a graft sculpted from β-tricalcium phosphate blocks. Grafts were secured with sutures or were self-retaining. Rabbit larynges were harvested according to the following schedule: one at 1 week, one at 3 months, and two each at 2 weeks, 4 weeks, 6 months, and 1 year after graft implantation. Specimens were evaluated grossly for overall graft incorporation. Sections through the graft substance were prepared for histology. All sections were reviewed by a pathologist for evidence of vascular ingrowth, granulation tissue, inflammation, epithelialization, and graft resorption. There were no major postoperative complications. Gross examination revealed persistent widening of the airway at the level of graft placement. Histologic evaluation of the larynges showed growth of new blood vessels within all specimens and absence of significant granulation tissue near the airway lumen. The graft was at least partially covered by an epithelium in seven of the 10 specimens. Evidence of graft resorption was present as early as 4 weeks after implantation, with replacement of the graft substance by fibrous tissue, fatty tissue, bone, or cartilage. β-tricalcium phosphate grafts can be used safely in airway reconstruction procedures in rabbits. Further research is necessary to demonstrate its safety in human airway reconstruction in addition to further clarifying the processes of graft resorption and integration. NA Laryngoscope, 126:E255-E260, 2016.

Bone grafting materials in critical defects in rabbit calvariae. A systematic review and quality evaluation using ARRIVE guidelines.

To perform a systematic literature review of the regenerative potential of bone substitutes used to fill critical size defects (CSDs) in rabbit calvariae; to determine the quality of the included studies using ARRIVE guidelines. An Internet search was performed in duplicate using MEDLINE, PubMed and Google Scholar databases (without restrictions on publication date) for studies reporting the regenerative potential of bone substitutes in CSDs in rabbit calvariae. Four parameters were analyzed by histomorphometry: new bone formation (NB); defect closure (DC); residual graft (RG); and connective tissue (CT). Animal Research Reporting in In Vivo Experiments (ARRIVE) guidelines (a list of 20 aspects for scoring texts and ensuring comparison between different experimental studies in animals) were used to evaluate the quality of the selected works. Twenty-one manuscripts were included. CSDs with 15mm were predominant (57.14%). Only one study described the four histomorphometric parameters. NB formation was analyzed in 15 studies (71.42%) and was higher for particulate autogenous bone grafts (range 52.1-82%) after 12weeks. DC was evaluated in six studies (28.57%) and was higher for fragmented adipose tissue grafts (range 53.33-93.33%) after 12weeks. RG was evaluated in four studies (19.04%) and was higher for hydroxyapatite/beta-tricalcium phosphate grafts with silica (HA/ß-TCP + Si) (range 35.78-47.54%) at 12weeks. CT was evaluated in two studies (9.5%) and was higher for HA/ß-TCP + membrane (44.2%) at 12weeks. Quality evaluation identified three items (title, introduction/objectives and experimental procedure) (15%) with excellent scores, 10 items (abstract, introduction/background, methods/ethical statement, experimental animals, experimental outcomes, statistics, results/baseline data, outcome/estimation and discussion interpretation/scientific implications) (50%) with average scores, and seven items (housing and husbandry, sample size, allocation, numbers analyzed, adverse effects, general applicability/relevance and funding) (35%) obtained poor scores. Only one manuscript obtained a quality evaluation considered as excellent. Autogenous bone grafts increase NB. DC is enhanced by the use of fragmented adipose tissue. RG remains in the defect for longer when hydroxyapatite/beta-tricalcium phosphate with silica is used, and more CT can be expected when hydroxyapatite/beta-tricalcium phosphate with silica grafts are covered by a membrane. The addition of stem cells of different origins to grafting materials enhances bone formation in early healing periods. The ARRIVE guidelines are still insufficiently used and the overall quality of studies remains low.

熱可塑性吸収性プレートとβ-TCP 顆粒を用いた三次元的骨再生の実験的評価

We used the combination of a thermoplastic bioresorbable plate and a beta-tricalcium phosphate (β -TCP) grafting substitute for bone defects to induce three-dimensional bone regeneration and evaluated the regenerated bone by histological, ultrastructual, and elemental mapping analyses. Standardized bone defects surgically formed in rat calvariae were filled with β -TCP particles (OSferion®) and covered with a domeshaped plate (LactoSorb®). In the control group, bone defects were covered with a plate without grafting β -TCP particles. In the experimental group, newly formed woven bone extended from the bottom of the defects at 2 weeks. Osteopontin immunopositivity was seen throughout the β -TCP particles grafted in the bone cavity. At the bottom of the cavity, alkaline phosphatase (ALP)-positive cells and tartrate-resistant acid phosphatase (TRAP)-positive cells were localized on the β -TCP particles. At 4 weeks, the new bone had reached half of the height of the cavity, and at 8 weeks, it was close to the plate. At 24 weeks, the new bone had reached the height of the plate and showed histological characteristics of compact bone. The volume of β -TCP particles had decreased and was replaced by new bone. Analyses using a transmission electron microscope and electron probe microanalyzer also revealed that the new bone showed the properties of compact bone. In the control group, the new bone encapsulated with fibrous tissue did not have sufficient height to reach the dome-shaped plate. The results indicate that new bone established by the combination of a thermoplastic bioresorbable plate and a β -TCP grafting substitute might be an alternative material for mandible reconstruction.

Osteostimulatory effect of bone grafts on fibroblast cultures.

Objective:We analyzed the morphological changes and alkaline phosphatase (ALP) level in fibroblast, which is indicative of their functional ability when cultured in three different commercially available graft materials with osseoconductive property.Materials and Methods:Fibroblasts obtained from fifth passage were seeded within three different bone substitutes (bovine hydroxyapatite [HA] [Osseo-graft®], β-tricalciumphosphate [RTR®], bovine HA [Bio-oss®]) and incubated under standard cell culture conditions. 10 samples in each group were evaluated for cell morphology and alkaline phosphates activity using scanning electron microscopy and spectrophotometric analysis on the 7th day of culture.Results:Fibroblast cultured with RTR® showed changes in morphology and increase in ALP activity when compared to fibroblast cultured with Osseo-graft® and Bio-oss®.Conclusion:Alkaline phosphatase activity was observed in fibroblasts when cultured with three types of commercially available bone grafts. ALP activity was highest when cultured with β-tricalcium phosphate graft material indicating its better bone regenerating capacity of this graft material.

Comparison of osteoconductive properties of three different β-tricalcium phosphate graft materials: A pilot histomorphometric study in a pig model

AimsThe aim of this study was to compare the de novo bone formation ability and osteoconductive effects of three different β-tricalcium phosphate (β-TCP) graft materials. The micro-architectural parameters of the newly formed bone tissues were also compared among the different graft materials. Material and methodsEight male Swiss domestic pigs were used in the study. Five bony defects were made with a trephine bur. Three of the defects were filled with Cerasorb®, Kasios® and Poresorb®. The fourth defect was filled with an autogenous bone graft. The last defect remained empty. All subjects were sacrificed after 8 weeks. ResultsWhen compared to a negative control group, significant healing was observed in all the groups except the Cerasorb group. The osteoconductivity of the Poresorb group was better than that of the other groups (p < 0.05). The difference in the osteoconductivity of the Kasios and Cerasorb groups was statistically significant (p < 0.05). Comparison of the micro-architectural properties of newly formed bone tissues retrieved from the defects showed that those filled with Poresorb were the best. Conclusionβ-TCP materials show different results in terms of the volume and characteristics of new bone formation, although they have a similar chemical structure.

Opening Wedge High Tibial Osteotomy Using Tricalcium Phosphate Wedge

Objectives:High tibial osteotomy is a standard procedure indicated for early medial sided osteoarthritis in varus knees. In this study, we present the early results of high tibial open wedge osteotomy cases using beta-tricalcium phosphate as a graft substitute and Otis-c plate.Methods:Between years 2010 and 2013, 47 cases of (34F, 13 M) medial compartmental gonarthrosis with genu varum deformity treated with high tibial osteotomy, were evaluated with at least one year follow-up, preoperatively both clinically and radiologically. Clinical evaluation involved functional assessment and pain evaluation using Lysholm and visual analog scale (VAS) scores, including knee range-of-motion. Radiological evaluation included medial joint space measurements on weight bearing knee radiographs with measurements of varus angle and posterior tibial slope. Surgical procedure included standard arthroscopy followed by medial sided opening wedge osteotomy with correction of the varus deformity using β- tricalcium phosphate graft substitute and fixation of the osteotomy site using Otis-C plate and locking screws. All patients were evaluated at the end of minimum one-year follow-up period.Results:Mean age of the patients was 56,7 (50- 65) years and mean follow-up period was 24,5 (12- 44) months. Mean duration of surgery was 47,4±10.2 minutes. No case of nonunion, delayed union, neurovascular injury or iatrogenic fracture was encountered. Two cases developed deep vein thrombosis and one case developed superficial wound infection managed successfully by local debridement with retention of implants and antibiotics. Mean duration of union was 13,4±2.7 weeks. Mean preoperative and follow-up range-of-motion were measured as 131±8.9 and 129±9.1 respectively with no statistical difference. Preoperative and follow-up VAS scores showed significant difference as 7.6±1.76 and 2.3±1.08 respectively (p=0.001). Also Lysholm scores improved significantly at the end of the follow-up period (43.23±4.01 vs. 76.3±3.7 p<0,001). Radiological evaluation revealed mean correction angle of 10.84±2.70 degrees at follow-up. Mean posterior tibial slope was measured relatively unchanged (8.6±1.70° degrees preoperatively versus 8.2±2.30° follow-up). Medial joint space width measurements showed a significant increase (pre-op 3.7±1.6 mm. versus 4.6±1.32 mm. at the follow-up (p<0.001)).Conclusion:Medial opening wedge osteotomy for treatment of early medial compartment gonarthrosis in varus knees is still a valuable option. Our short term preliminary results using beta-tricalcium phosphate wedge graft substitute and Otis-c plate-screw osteosynthesis revealed satisfactory short term clinical and radiological results with acceptable complication rates.

Histologic and histomorphometric study of bone repair around short dental implants inserted in rabbit tibia, associated with tricalcium phosphate graft bone

The use of short dental implants represents one way to overcome this limitation, in association with bone grafting procedures. Tricalcium phosphate-based grafts are among those widely used. The purpose of this study was to assess the biocompatibility of this biomaterial in the coverage of bone defects around short dental implants. Ten New Zealandrabbits were used in this study, each animal received 4 implants, two were placed in the right tibia region (control group) and two in the left tibia region (test group). Forty implants were used, with 4mm diameter and 6mm length. For the control group, holes 6 mmdeep were made, and the implants were then inserted at the level of bone tissue. In the control group, the implants of 6 mmin length were inserted to its full length, while in the test group, the same implant was inserted up to 4 mmand left exposed 2 mm. These 2 mmexposed were coated with a bone substitute of tricalcium phosphate and a collagen membrane. After three months, the animals were prepared for histomorphometric analysis, which showed that the control group had a higher number of osteoblasts per μm 2 than the test group (p < 0.001). It was concluded that under these experimental conditions, tricalcium phosphate showed tissue biocompatibility and osteoconductive potential.

Engineering a vascularized collagen-β-tricalcium phosphate graft using an electrochemical approach

Vascularization of three-dimensional large synthetic grafts for tissue regeneration remains a significant challenge. Here we demonstrate an electrochemical approach, named the cell electrochemical detachment (CED) technique, to form an integral endothelium and use it to prevascularize a collagen-β-tricalcium phosphate (β-TCP) graft. The CED technique electrochemically detached an integral endothelium from a gold-coated glass rod to a collagen-infiltrated, channeled, macroporous β-TCP scaffold, forming an endothelium-lined microchannel containing graft upon removal of the rod. The in vitro results from static and perfusion culture showed that the endothelium robustly emanated microvascular sprouting and prevascularized the entire collagen/β-TCP integrated graft. The in vivo subcutaneous implantation studies showed that the prevascularized collagen/β-TCP grafts established blood flow originating from the endothelium-lined microchannel within a week, and the blood flow covered more areas in the graft over time. In addition, many blood vessels invaded the prevascularized collagen/β-TCP graft and the in vitro preformed microvascular networks anastomosed with the host vasculature, while collagen alone without the support of rigid ceramic scaffold showed less blood vessel invasion and anastomosis. These results suggest a promising strategy for effectively vascularizing large tissue-engineered grafts by integrating multiple hydrogel-based CED-engineered endothelium-lined microchannels into a rigid channeled macroporous scaffold.

Influence of bone morphogenetic protein and proportion of hydroxyapatite on new bone formation in biphasic calcium phosphate graft: Two pilot studies in animal bony defect model

PurposeThe purpose of these two pilot studies using animal bony defect models was to evaluate the influence of bone morphogenetic protein (BMP) and proportion of hydroxyapatite (HA)/beta-tricalcium phosphate (β-TCP) in biphasic calcium phosphate (BCP) graft on new bone formation. MethodsIn this study, four kinds of synthetic osteoconductive bone materials known for bone growth scaffold, OSTEON™II(HA:β-TCP 30:70), OSTEON™III (HA:β-TCP 20:80), OSTEON™II Collagen, and OSTEON™III Collagen, were prepared as BCP graft materials. In pilot study 1, three BCP materials (OSTEON™II, OSTEON™III, and OSTEON™II Collagen) were grafted in rabbit calvarial defects after impregnating in rhBMP-2. OSTEON™II without the rhBMP-2 impregnation was included in the study as the control. The amount of new bone was examined and measured histologically at 2, 4, and 8 weeks. In pilot study 2, four BCP materials (OSTEON™II, OSTEON™III, OSTEON™II Collagen, and OSTEON™III Collagen) were grafted in beagle dog mandibular defects after soaking in the rhBMP-2. The amount of total bone and new bone were measured three-dimensionally using microCT and healing process was examined histologically at 2, 4, and 8 weeks. ResultsIn pilot study 1, rhBMP-2 impregnated groups showed more new bone formation than the rhBMP-2 free group. In pilot study 2, increased new bone formation was observed in time-dependent manner after graft of BCP and BCP-collagen (OSTEON™II, OSTEON™III, OSTEON™II Collagen, and OSTEON™III Collagen) impregnated with rhBMP-2. Also, BCP with a higher proportion of HA (30% HA) showed more favorable result in new bone formation and space maintenance, especially at the 8 weeks. ConclusionFrom the results of the pilot studies, rhBMP-2 played positive roles in new bone formation and BCP could become a scaffold candidate for rhBMP-2 impregnation to induce new bone formation. Moreover, BCP with a higher proportion of HA (30% HA) could be considered more appropriate for rhBMP-2 carrier.

Effect of a tunnel-structured β-tricalcium phosphate graft material on periodontal regeneration: a pilot study in a canine one-wall intrabony defect model.

Tissue regeneration is affected by the porosity, chemical properties and geometric structure of graft materials. Regeneration of severe periodontal defects, such as one-wall intrabony defects, is difficult because of reduced tissue support, and bone grafts are commonly used in such cases. In the present study, a tunnel-structured β-tricalcium phosphate (tunnel β-TCP) graft material designed to stimulate bone formation was fabricated. The objective of this pilot study was to evaluate the effect of this graft material on periodontal regeneration in one-wall intrabony defects in dogs. Six male beagle dogs were used in this study. First, the mandibular second and third incisors were extracted. Experimental surgery was performed 12 wk after tooth extraction. Bilateral 4 × 8 mm (width × depth) one-wall intrabony defects were created in the mesial side of the mandibular canines. At the experimental sites, the defects were filled with tunnel β-TCP, whereas the control defects were left empty. Twelve weeks after surgery, qualitative and quantitative histological analyses were performed. There were no signs of clinical inflammation 12 wk after surgery. Coronal extension indicative of new bone formation was higher at the experimental sites than at the control sites, although the differences between both the sites in the newly formed cementum and connective tissue attachment were not significant. Newly formed periodontal ligament and cementum-like tissue were evident along the root surface at the experimental sites. The inner surface of the tunnels was partially resorbed and replaced with new bone. New blood vessels were observed inside the lumens of tunnel β-TCP. Tunnel β-TCP serves as a scaffold for new bone formation in one-wall intrabony defects.

Effect of Silicon-Doped Calcium Phosphate Bone Substitutes on Bone Formation and Osteoblastic Phenotype Expression &lt;i&gt;In Vivo&lt;/i&gt;

This study evaluates the effect of two novel particulate silicon-doped calcium phosphate graft materials as compared to the currently clinically used material β-TCP on osteogenesis and bone formation after implantation in critical-size defects the sheep scapula. These materials were developed in order to create biodegradable bone substitute materials that degrade rapidly, but still stimulate osteogenesis at the same time, thereby resulting in bone repair and regeneration with fully functional bone tissue. All bone substitute materials studied facilitated excellent bony regeneration of critical-size defects in the sheep scapula. Of the three grafting materials studied, the calcium alkali orthophosphate material with the crystalline phase Ca2KNa (PO4)2, with a small amorphous portion containing magnesium potassium phosphate and a small addition of sodium magnesium silicate had the greatest stimulatory effect on bone formation and expression of osteogenic markers, while exhibiting the highest biodegradability.