Evaluation of a novel biphasic calcium phosphate in standardized bone defects: a histologic and histomorphometric study in the mandibles of minipigs

OBJECTIVE: A novel biphasic calcium phosphate (CaP) granulate consisting of hydroxyapatite (HA) and beta-tricalciumphosphate (TCP) was compared with pure HA and pure TCP and with autograft as positive control. MATERIALS AND METHODS: Four standardized bone defects were prepared in both mandibular angles of 16 minipigs and grafted with autogenous bone chips, HA, HA/TCP (60% : 40%), or TCP. Histologic and histomorphometric analysis of bone formation and graft degradation followed healing periods of 2, 4, 8, and 24 weeks. RESULTS: 2 weeks: more bone formation in defects filled with autograft than with the three CaP materials (P<0.05). 4 weeks: bone formation differed significantly (P<0.05) between all four materials (autograft>TCP>HA/TCP>HA). 8 weeks: more bone formation in defects with autograft and TCP than with HA/TCP (P<0.05), and HA/TCP had more bone formation than HA (P<0.05). 24 weeks: no difference in bone formation between the groups. Autograft and TCP resorbed quickly and almost completely over 8 weeks, whereas HA/TCP and HA showed limited degradation over 24 weeks. CONCLUSION: All defects healed with mature lamellar bone and intimate contact between bone and the remaining graft material. The rate of bone formation corresponded to the content of TCP in the CaP materials.     

Bone morphogenetic protein-2 enhances bone formation when delivered by a synthetic matrix containing hydroxyapatite/tricalciumphosphate

PURPOSE: The aim of the present study was to test whether or not a synthetic matrix consisting of a polyethylene glycol (PEG) hydrogel containing recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with grafting materials enhances bone regeneration compared with grafting alone or empty control sites. MATERIAL AND METHODS: In each of 10 rabbits, four titanium cylinders were screwed in perforated slits made in the external cortical bones of the calvaria. The following four treatment modalities were randomly allocated: (1) empty control, (2) a combination of a PEG matrix and hydroxyapatite/tricalciumphosphate (HA/TCP) granules and a combination of a PEG matrix containing either 10 microg/ml (3) or 30 microg/ml (4) of BMP-2 and HA/TCP granules. After 8 weeks, the animals were sacrificed and ground sections were obtained for histological analysis. For statistical analysis repeated measures ANOVA and subsequent pairwise Student's t-test were applied (P<0.01). RESULTS: Histomorphometric analysis showed an average area fraction of newly formed bone of 13.96+/-5.98% for the empty control, 15.16+/-7.95% for the PEG and HA/TCP group, 26.32+/-8.56% for the group containing 10 mug rhBMP-2/ml, and 30.15+/-7.63% for the group containing 30 microg rhBMP-2/ml. Statistical analysis revealed significantly more newly formed bone in the two rhBMP-2 groups compared with the PEG and HA/TCP group and with the empty control. Regarding the surface fraction of the HA/TCP graft particles covered with newly formed bone the addition of rhBMP-2 revealed a more than two-fold increase compared with cylinders containing HA/TCP granules without rhBMP-2. This difference reached statistical significance. CONCLUSIONS: It is concluded that rhBMP-2 significantly enhances bone regeneration in rabbits when delivered by a synthetic matrix containing HA/TCP. This synthetic PEG matrix containing HA/TCP granules apparently fulfills a number of criteria required for an ideal carrier system for rhBMP-2.     

The bone regenerative effect of platelet-rich plasma in combination with an osteoconductive material in rat cranial defects

The effect of platelet-rich plasma (PRP) on bone regeneration, in combination with an osteoconductive material, was evaluated in a rat model. Cranial defects, 6.2 mm in diameter, were filled with HA/beta-TCP particles, HA/beta-TCP particles combined with PRP and HA/beta-TCP particles combined with PRP gel, where some were left empty as a control. After 4 weeks of implantation histological, histomorphometrical and micro-computed tomography analyses revealed no difference in new bone formation among the groups. Further, no additional effect of PRP gel in comparison with PRP liquid was detected, except for the increased handling capacity of the graft. These findings suggest that PRP had no positive effect on bone formation in addition to an osteoconductive material after an implantation period of 4 weeks. Also, no negative effect was seen, and neither PRP nor HA/beta-TCP hampered bone ingrowth into the defects.     

Back‐scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate

Objectives: To compare resorption of a synthetic biphasic calcium phosphate (BCP) bone–graft substitute with deproteinized bovine bone (DBB) used for human maxillary sinus augmentation. Materials and methods: Eleven patients underwent bilateral maxillary sinus floor augmentation with DBB in one side and a BCP (40%β‐tricalcium phosphate (β‐TCP) and 60% hydroxyapatite) in the contralateral side. Simultaneously, with the augmentation on each side a microimplant was placed vertically from the top of the alveolar crest penetrating the residual bone and the grafting material. Eight months after initial surgery the microimplants were retrieved with a surrounding bone core. The composition of residual graft material and surrounding bone was analysed by scanning electron microscopy and energy dispersive X‐ray spectroscopy. Results: Residual graft material of both types was present as 10–500 μm particles in direct contact with, or completely surrounded by, newly formed bone; smaller particles were also present in non‐mineralized tissue. In the case of BCP the bone–graft substitute interface showed evidence of superficial disintegration of particles into individual grains. Median Ca/P ratios (at.%), determined from >200 discreet sites within residual graft particles and adjacent bone, were: DBB: 1.61 (confidence interval [CI] 1.59–1.64); BCP: 1.5 (CI 1.45–1.52); DBB‐augmented bone: 1.62 (CI 1.59–1.66); BCP‐augmented bone: 1.52 (CI 1.47–1.55); P=0.028 for DBB vs. BCP and DBB‐ vs. BCP‐augmented bone. The reduction in Ca/P ratio for BCP over the healing period is consistent with the dissolution of β‐TCP and reprecipitation on the surface of calcium‐deficient hydroxyapatite. Conclusion: The β‐TCP component of BCP may be gradually substituted by calcium‐deficient hydroxyapatite over the healing period. This process and superficial degranulation of BCP particles may influence the progress of resorption and healing. To cite this article:
Lindgren C, Hallman M, Sennerby L, Sammons R. Back‐scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate.
Clin. Oral Impl. Res. 21 , 2010; 924–930.
doi: 10.1111/j.1600‐0501.2010.01933.x     

Early effect of platelet-rich plasma on bone healing in combination with an osteoconductive material in rat cranial defects

OBJECTIVE: The early effect of platelet-rich plasma (PRP) on bone regeneration in combination with dense biphasic hydroxyl apatite (HA)/beta-tricalcium phosphate (TCP) particles (ratio 60%/40%) was evaluated in rat cranial defects with a diameter of 6.2 mm. We hypothesize that PRP exerts its beneficial effect on bone regeneration within the first and second week after application in a bone defect combined with an osteoconductive material. MATERIALS AND METHODS: Forty-five rats were used in the study, in which always one cranial defect was created. The defects were filled with HA/beta-TCP particles and HA/beta-TCP particles combined with PRP gel. Some defects were also left unfilled as control. One and two weeks after surgery specimens were retrieved for light microscopy [hematoxylin-eosin, trichrome staining (Masson modification Goldner) and basic fuchsin-methylene blue] and micro-CT analysis to evaluate bone formation and neovascularization. One-way analysis of variance was performed on the raw data obtained from micro-CT analyses. RESULTS: The histological evaluation showed no effect of PRP on bone formation and neovascularization for both implantation times. In the first week, the defect closure was evaluated subjectively to be between 10% and 50% in all samples, whereas no difference among the groups appeared to occur. After 2 weeks, complete bridging of the original bone defect was observed for most of the empty defects, as well as for the defects that contained HA/beta-TCP particles. The trichrome staining revealed no difference in the number of blood vessels between the PRP and non-PRP groups for both implantation times. The osteoconductive nature of dense HA/beta-TCP particles was confirmed, as the bone formation was guided by their outer surfaces and resulted in a larger amount of newly formed bone in comparison with the empty defects. The quantitative micro-CT analysis demonstrated a statistically significant difference in new bone formation between the empty defects and defects filled with particles after 1 week of implantation, but there was no difference between the non-PRP and PRP groups. In at the second week, no difference in bone formation among all groups was observed, whereas even the non-filled control defects were almost completely closed. CONCLUSIONS: A 6.2 mm cranial defect is not a critical-sized defect in rats. Rat PRP had no effect on the early stages of bone healing in addition to an osteoconductive material. Dense HA/beta-TCP particles showed a beneficial effect on bone formation already after 1 and 2 weeks of implantation in non-critical-sized cranial defects in rats.     

人骨髓间质干细胞的培养及成骨功能研究

目的　体外扩增人骨髓间质干细胞 (humanbonemarrow derivedmesonchymalstemcells,hBMMSCs) ,研究其生物学特征及体内、外成骨功能。方法　分离培养hBMMSCs,并对其形态、增殖动力学、碱性磷酸酶 (alkalinephosphatase,ALP)表达及体内、外成骨功能进行研究。结果　hBMMSCs可在体外培养扩增 ,群体倍增时间约为 3 5d。ALP检测表明 ,未经矿化诱导的hBMMSCs可表达少量ALP ,诱导后其表达量明显增高。vonkossa染色证实在矿化诱导液作用下hBMMSCs在体外可形成钙结节。体内成骨实验证实 ,1× 10 5个hBMMSCs接种到 30mm3 块状HA/TCP载体移植BALB/C裸小鼠皮下 3个月 ,可观察到层板状骨组织生成。结论　hBMMSCs是一种具有成骨潜能的前体细胞 ,经培养、扩增、诱导后 ,在体外可形成矿化结节 ,体内可在载体表面形成骨组织。     

Bone regeneration using a synthetic matrix containing a parathyroid hormone peptide combined with a grafting material

PURPOSE: The aim of the present study was to test whether a newly developed synthetic matrix made of polyethylene-glycol (PEG) containing a covalently bound peptide of the parathyroid hormone (PTH1-34) enhances bone regeneration compared to grafting procedures and to spontaneous healing. MATERIALS AND METHODS: In each of 16 rabbits used, 4 titanium cylinders were screwed into perforated slits made in the cortical bone of the calvaria. The cylinders were either left empty (control) or filled with 1 of the following: (1) PEG matrix and hydroxyapatite/tricalcium phosphate (HA/TCP) granules, (2) PEG matrix containing 100microg/mL of PTH and HA/TCP granules, or (3) PEG matrix containing 20microg/mL of PTH1-34 and HA/TCP granules. After 8 weeks, the animals were sacrificed, and ground sections were obtained for histology. RESULTS: Quantitative histomorphometry demonstrated a significantly increased amount of newly formed bone for PTH1-34 compared to sites treated with PEG and HA/TCP and to empty control sites (P < .01; analysis of variance and subsequent pairwise Student t test). The mean percentages of mineralized bone were 19.6%+/-6.0% for 100 microg/mL PTH, 18.0% +/- 6.2% for 20microg/mL PTH, 12.0% +/-6.5% for PEG and HA/TCP without PTH, and 10.5% +/-3.7% for the empty control. The mean areas of bone regenerated within the cylinders were 53.5% +/-22.7% for 100 microg/mL PTH, 51.1% +/-22.6% for 20 microg/mL PTH, 34.3% +/- 22.5% for PEG and HA/TCP without PTH, and 23.2% +/-10.1% for the empty control. DISCUSSION: Human and animal trials have demonstrated that daily systemic injection of PTH increases bone mineral density. The present study showed that local administration of PTH was also effective in stimulating bone formation. CONCLUSION: It is concluded that this synthetic PEG hydrogel containing a covalently bound peptide of the PTH combined with HA/TCP granules significantly stimulated in situ bone augmentation in rabbits.     

Comparison of osteogenic potential between apatite-coated poly(lactide-co-glycolide)/hydroxyapatite particulates and Bio-Oss

Previously, we developed a poly(lactide-co-glycolide)/nano-hydroxyapatite (PLGA/HA) composite that overcame the limitations of conventional ceramic bone substitutes. This was achieved by introducing a bone-like apatite layer on the composite to further enhance its osteogenic potential. In this study, we compared the osteogenic potential of the apatite-coated PLGA/HA particulates to that of Bio-Oss, a deproteinized bovine bone material. A mixture of fibrin gel and either apatite-coated PLGA/HA particulates or Bio-Oss was implanted into critical-size rat calvarial defects. As a control, fibrin gel was implanted alone into the defects. At eight weeks after treatment, histological examination showed new bone formation around the grafting materials, and bone formation was similar between the two groups. In the control group, bone was not regenerated and the defects were filled with fibrous tissues. This study showed that a synthetic bone graft material, apatite-coated PLGA/HA particulates, had a comparable bone regeneration potential to the bovine-derived bone graft material, Bio-Oss.     

Pore characteristics of bone substitute materials assessed by microcomputed tomography

Objectives: Pore configurations of alloplastic biomaterial scaffolds play a major role for new bone formation in vivo. Current studies on characteristics of pores in bone substitute materials focus on individual particles or single blocks. Thus, three‐dimensional (3‐D) architecture of particle aggregates, representing the clinical relevant in vivo situation is not adequately taken into account. The aim of this study was the visualization and quantification of pore properties, both of the scaffold structure of single particles as well as of the micro‐morphology of complex 3‐D aggregated particle‐conglomerates. Material and methods: In model experiments, standardized plexiglass cylinders were stuffed with commercial bone substitute material particles with diverse chemical composition (HA, β‐TCP, HA‐SiO₂, HA‐β‐TCP, bioactive glass), origin (phycogenic, bovine, synthetic) and granulation (50 μm–2000 μm). Analogue to establish procedures for native (human) bone samples, non‐fixed bone substitute materials were scanned by high‐resolution microcomputed tomography. In addition to computer animated two‐dimensional and 3‐D reconstruction of the samples, median pore thickness and pore size distribution were determined. Materials representative for their chemical constitution were documented by SEM imaging. Results: Investigated specimens significantly were different in micro‐morophology and pore properties, ranging from highly porous to rather solid. The most voluminous pores were localized interparticularly. Within one product line, the determined pore properties showed a significant correlation with single particle grain sizes. Conclusion: The generation and interpretation of μ‐CT based 3‐D pore models can provide further insight into the expected osteoconduction dynamics and therefore might serve as a basis for further modifications of scaffold size and geometry as well as for further invasive studies on the biological behaviour of the scaffolds.     

Effect of platelet-rich plasma on bone healing of autogenous bone grafts in critical-size defects

Aim: This study histologically analysed the effect of autogenous platelet-rich plasma (PRP), prepared according to a new semiautomatic system, on healing of autogenous bone (AB) grafts placed in surgically created critical-size defects (CSD) in rabbit calvaria.
Material and Methods: Sixty rabbits were divided into three groups: C, AB and AB/PRP. A CSD was created in the calvarium of each animal. In Group C (control), the defect was filled by blood clot only. In Group AB (autogenous bone graft), the defect was filled with particulate autogenous bone. In Group AB/PRP (autogenous bone graft with platelet-rich plasma), it was filled with particulate autogenous bone combined with PRP. All groups were divided into subgroups ( n =10) and euthanized at 4 or 12 weeks post-operatively. Histometric and histologic analyses were performed. Data were statistically analysed ( anova , t -test, p <0.05).
Results: Group C presented significantly less bone formation compared with Group AB and AB/PRP in both periods of analysis ( p <0.001). At 4 weeks, Group AB/PRP showed a statistically greater amount of bone formation than Group AB (64.44 ± 15.0% versus 46.88 ± 14.15%; p =0.0181). At 12 weeks, no statistically significant differences were observed between Groups AB and AB/PRP (75.0 ± 8.11% versus 77.90 ± 8.13%; p >0.05). It is notable that the amount of new bone formation in Group AB/PRP at 4 weeks was similar to that of Group AB at 12 weeks ( p >0.05).
Conclusion: Within its limitation, the present study has indicated that (i) AB and AB/PRP significantly improved bone formation and (ii) a beneficial effect of PRP was limited to an initial healing period of 4 weeks.     

Effect of vitamin D pretreatment of human mesenchymal stem cells on ectopic bone formation

Adult mesenchymal stem cells (MSCs) are used in contemporary strategies for tissue engineering. The MSC is able to form bone following implantation as undifferentiated cells adherent to hydroxyapatite (HA)/tricalcium phosphate (TCP) scaffolds. Previous investigators have demonstrated that human MSCs (hMSCs) can be differentiated to osteoblasts in vitro by the inclusion of vitamin D and ascorbic acid. The aim of this study was to compare the osteogenic potential of predifferentiated and undifferentiated bone marrow-derived, culture-expanded hMSCs adherent to synthetic HA/TCP (60%/40%) following subcutaneous engraftment in severe combined immunodeficiency (SCID) mice. During the final 3 days of culture, cells were grown in Dulbecco's modified Eagle's medium containing 10% fetal calf serum and antibiotics or media containing 25-mM calcium supplementation with vitamin D and ascorbic acid. Four weeks following implantation in SCID mice, scoring analysis of bone formation within the cubes revealed the absence of bone formation in unloaded cubes. Bone formation compared by a qualitative bone index was 7.23% for undifferentiated cells compared to 5.20% for differentiated cells. Minimal resorption was observed at this early time point. In this ectopic model, predifferentiation using a combination of vitamin D and ascorbic acid failed to increase subsequent bone formation by implanted cells. Following implantation of hMSCs adherent to an osteoconductive scaffold, host factors may contribute dominant osteoinductive signals or impose inhibitory signals to control the fate of the implanted cell. Predifferentiation strategies require confirmation in vivo.     

引导组织再生术与联合应用植骨术治疗牙周骨内缺损的临床研究

比较引导组织再生术（GTR）与联合骨移植术治疗牙周骨内缺损的临床疗效。方法 选取45例牙周炎重度垂直骨吸收的患牙,随机平均分为翻瓣术组、单纯GTR组及联合植骨组。分别在术前和术后1年记录牙周袋深度、附着丧失、牙龈退缩并进行比较。结果 术前、后自身比较,3组的各项检查指标均有显著性改变(P<0．05);与翻瓣组相比,单纯GTR组及联合植骨组牙周袋深度及附着丧失减少更显著,具有统计学差异(P<0．05),而龈退缩量无统计学差异。单纯GTR组与联合植骨组相比各项临床指标均无统计学差异。结论 与单纯翻瓣术相比,引导组织再生术与联合应用植骨术治疗垂直型牙周骨内缺损均可获得更好的临床效果,GTR联合植骨术稍优于单纯GTR术。     

Ridge augmentation and maxillary sinus grafting with a biphasic calcium phosphate: histologic and histomorphometric observations

Objectives: This retrospective study reports on histologic and histomorphometric observations performed on human biopsies harvested from sites augmented exclusively by biphasic calcium phosphate [BCP: hydroxyapatite (HA)/ tricalcium phosphate (TCP) 60/40] and healed for a minimum of 6 months.
Materials and methods: Five patients benefited from three augmentation regimens (i.e.: one-stage lateral augmentation; two-stage lateral augmentation; and two-stage sinus grafting). In all patients, a degradable collagen membrane served as a cell-occlusive barrier. Core biopsies were obtained from lateral as from crestal aspects 6–10 months after augmentation surgeries. For histologic and histomorphometric evaluations, the non-decalcified tissue processing was performed.
Results: The histological examination of 11 biopsies showed graft particles frequently being bridged by the new bone, and a close contact between the graft particles and newly formed bone was seen in all samples. The mean percentages of newly formed bone, soft tissue compartment, and graft material were 38.8% (±5.89%), 41.75% (±6.08%), and 19.63% (±4.85%), respectively. Regarding bone-to-graft contact values, the percentage of bone coverage of graft particles for all biopsies ranged from 27.83% to 80.17%. The mean percentage of bone coverage was 55.39% (±13.03%).
Conclusions: Data from the present study demonstrated osteoconductivity scores for the BCP material (HA/TCP 60/40) in patients resembling those previously shown for grafting materials of xenogenic and alloplastic origin.     

Rosuvastatin 1.2 mg In Situ Gel Combined With 1:1 Mixture of Autologous Platelet‐Rich Fibrin and Porous Hydroxyapatite Bone Graft in Surgical Treatment of Mandibular Class II Furcation Defects: A Randomized Clinical Control Trial

Background: A wide range of regenerative materials have been tried and tested in the treatment of furcation defects. Rosuvastatin (RSV) is a new synthetic, second‐generation, sulfur‐containing, hydrophilic statin with potent anti‐inflammatory and osseodifferentiation mechanisms of action. Platelet‐rich fibrin (PRF) is a platelet concentrate having sustained release of various growth factors with regenerative potential to treat periodontal defects. Porous hydroxyapatite (HA) bone grafting material has a clinically satisfactory response when used to fill periodontal intrabony defects. This double‐masked randomized study is designed to evaluate the potency of a combination of 1.2 mg RSV in situ gel with a 1:1 mixture of autologous PRF and HA bone graft in the surgical treatment of mandibular Class II furcation defects compared with autologous PRF and HA bone graft placed after open‐flap debridement (OFD). Methods: One hundred five mandibular furcation defects were treated with OFD + placebo gel (group 1), PRF + HA with OFD (group 2), or 1.2 mg RSV gel + PRF + HA with OFD (group 3). Clinical and radiologic parameters (i.e., probing depth [PD], relative vertical and relative horizontal clinical attachment level [rvCAL and rhCAL], intrabony defect depth, and percentage of defect fill) were recorded at baseline and 9 months postoperatively. Results: Mean PD reduction was greater in group 2 (3.68 ± 1.07 mm) and group 3 (4.62 ± 1.03 mm) than group 1 (2.11 ± 1.25 mm), and mean rvCAL and rhCAL gain were greater in group 2 (3.31 ± 0.52 and 2.97 ± 0.56 mm, respectively) and group 3 (4.17 ± 0.70 and 4.05 ± 0.76 mm) compared with group 1 (1.82 ± 0.78 and 1.62 ± 0.64 mm). A significantly greater percentage of mean bone fill was found in group 2 (54.69% ± 1.93%) and group 3 (61.94% ± 3.54%) compared with group 1 (10.09% ± 4.28%). Conclusions: Treatment of furcation defects with 1.2 mg RSV in situ gel combined with autologous PRF and porous HA bone graft results in significant improvements of clinical and radiographic parameters compared with OFD alone. These results imply that the combination of RSV, PRF, and HA has synergistic effects, explaining their role as a regenerative material in the treatment of furcation defects.     

Histological evaluation of sinus augmentation using platelet rich plasma (PRP): a case series

The use of Platelet Rich Plasma (PRP) in conjunction with autogenous bone graft materials has recently been advocated for use in sinus augmentation surgery as a means of enhancing both quantity and quality of newly forming bone. The use of PRP is based on the premise that autogenous plasma, rich in platelets, contributes large quantities of mitogenic polypeptides such as Platelet Derived Growth Factor (PDGF), Transforming Growth Factor-b (TGF-b) and Insulin-like Growth Factor-I (IGF-I), thereby enhancing osteogenesis. The aim of this study was to evaluate the potential of PRP to enhance bone formation following sinus augmentation with different bone derivative/substitute materials (DFDBA, FDBA, Xenograft, Bioactive Glass). This study presents histology of trephine-obtained core samples from five clinical cases in which sinus augmentation was performed with PRP combined with bone derivatives/substitutes. Histological evaluation of this case series consistently revealed the presence of residual graft particles surrounded by loose connective tissue, with a limited amount of newly formed bone. The findings suggest that the addition of PRP to bone derivative/substitute materials may not significantly enhance bone formation in the maxillary sinus area.     

Osteogenic potential of cultured human periosteum-derived cells – A pilot study of human cell transplantation into a rat calvarial defect model

BACKGROUND: Periosteum shows osteogenic potential and has received considerable attention as a grafting material for the repair of bone and joint defects. The osteogenic potential of cultured periosteal cells has also been reported. The findings of bone formation induced by cultured human periosteum-derived cells using a rat model are presented. MATERIAL AND METHODS: Human mandibular periosteum was placed into a culture medium with 10% foetal bovine serum for 14 days. After reaching confluence, periosteal cells were re-suspended with 0.25% trypsin/EDTA and then re-cultured three dimensionally on a collagen sponge. The periosteal cell/collagen complex was grafted into rat calvarial defects and an immunosuppressant (FK506, 1.0 mg/kg/day) was administered intramuscularly. At 2, 3, and 5 weeks postoperatively, grafted tissue was extirpated and compared histologically and radiographically with tissue from a collagen-only grafted group. RESULTS: In the experimental group, periosteal cells had proliferated and differentiated into osteogenic cells by 2 weeks post grafting. At 3 weeks, new bone formation was evident. By 5 weeks, bone growth was observed and new calcification was detected in the defect. CONCLUSION: Cultured human periosteum-derived cells showed osteogenic potential in a xenogeneic graft model using rat calvarial defects.     

Clinical and radiographic evaluation of the efficacy of platelet-rich plasma combined with hydroxyapatite bone graft substitutes in the treatment of intra-bony defects in maxillofacial region

Objective. The aim of this study is to evaluate the efficacy of platelet-rich plasma (PRP) clinically and radiographically when combined with bovine derived hydroxyapatite (HA) bone grafting materials and resorbable collagen membranes for the treatment of intra-bony defects frequently seen at the distal aspect of mandibular second molars following the surgical extraction of fully impacted mandibular wisdom teeth. Study design. Eighteen patients were scheduled for post-operative visits at 1, 3 and 6 months post-operatively, probing depths were measured and digital panoramic radiographs were taken. Results. There were no significant differences on probing depths among two groups. Radiographic assessment also showed no significant difference among groups at 1st and 6th month intervals, while 3 months post-operatively the amount of radiographic density at the PRP side was significantly higher. Conclusion. Combined use of PRP and bovine-derived HA graft materials for the treatment of intra-bony defects might be an appropriate approach when the main goal is providing earlier bone regeneration.     

Bone regeneration in the presence of a synthetic hydroxyapatite/silica oxide-based and a xenogenic hydroxyapatite-based bone substitute material

Objectives: A comparison of synthetic hydroxyapatite/silica oxide, xenogenic hydroxyapatite‐based bone substitute materials with empty control sites in terms of bone regeneration enhancement in a rabbit calvarial four non‐critical‐sized defect model. Methods: In each of six rabbits, four bicortical calvarial bone defects were generated. The following four treatment modalities were randomly allocated: (1) empty control site, (2) synthetic hydroxyapatite/silica oxide‐based (HA/SiO) test granules, (3) xenogenic hydroxyapatite ‐based granules, (4) synthetic hydroxyapatite/silica oxide ‐based (HA/SiO) test two granules. The results of the latter granules have not been reported due to their size being three times bigger than the other two granule types. After 4 weeks, the animals were sacrificed and un‐decalcified sections were obtained for histological analyses. For statistical analysis, the Kruskal–Wallis test was applied (P<0.05). Results: Histomorphometric analysis showed an average area fraction of newly formed bone of 12.32±10.36% for the empty control, 17.47±6.42% for the xenogenic hydroxyapatite ‐based granules group, and 21.2±5.32% for the group treated with synthetic hydroxyapatite/silica oxide ‐based granules. Based on the middle section, newly formed bone bridged the defect to 38.33±37.55% in the empty control group, 54.33±22.12% in the xenogenic hydroxyapatite ‐based granules group, and to 79±13.31% in the synthetic hydroxyapatite/silica oxide ‐based granules group. The bone‐to‐bone substitute contact was 46.38±18.98% for the xenogenic and 59.86±14.92% for the synthetic hydroxyapatite/silica oxide‐based granules group. No significant difference in terms of bone formation and defect bridging could be detected between the two bone substitute materials or the empty defect. Conclusion: There is evidence that the synthetic hydroxyapatite/silica oxide granules provide comparable results with a standard xenogenic bovine mineral in terms of bone formation and defect bridging in non‐critical size defects. To cite this article:
Kruse A, Jung RE, Nicholls F, Zwahlen RA, Hämmerle CHF, Weber FE. Bone regeneration in the presence of a synthetic hydroxyapatite/silica oxide ‐based and a xenogenic hydroxyapatite ‐based bone substitute material.
Clin. Oral Impl. Res. 22 , 2011; 506–511
doi: 10.1111/j.1600‐0501.2010.02039.x     

A Prospective Study Involving the Use of Platelet Rich Plasma in Enhancing the Uptake of Bone Grafts in the Oral and Maxillofacial Region

Abstract

Platelet-rich plasma (PRP) is an autologous product that contains highly concentrated number of platelets in a small volume of plasma, derived from whole blood by gradient density centrifugation. It has been speculated that local growth factors in human platelets (insulin-like growth factor, IGF; transforming growth factor, TGF-β; platelet derived growth factor, PDGF) would enhance healing of grafts and also counteract resorption. The aim of this study was to evaluate efficacy of PRP on early healing after autogenous bone grafting. Of the twenty patients selected ten were treated with autogenous bone graft and PRP (PRP group) and other ten with autogenous bone graft alone (non-PRP group). PRP group consisted of two benign tumor of mandible, one post surgical defect, two unilateral alveolar cleft, one bilateral alveolar cleft with skeletal class III malocclusion, one maxillary hypoplasia, one oronasal fistula, one recurrent tumor of mandible, one multiple impacted mandibular teeth. Non-PRP group consisted of seven benign tumor of jaw, one keratocyst odontogenic tumor, one orbital blow out fracture, one residual traumatic defect. Biopsies were taken in the native bone, PRP treated grafted bone, grafted bone without PRP at 3 months to assess the maturity of bone. Radiographic imaging was performed by panoramic radiography at 3 and 6 months to evaluate bone opacity of grafted bone on comparison with native bone and computerized tomography at 6 months to evaluate grafted bone morphologically and to measure bone density in Hounsfield units. Microscopic results showed that significantly more matured bone was formed at PRP treated sites as that of native bone and immature bone in controls after 3 months of healing. Bone opacity of PRP treated bone grafts was close to that of native bone than that of non-PRP treated bone grafts on panoramic radiograph at 3 and 6 months. There was graft loss in three cases and graft resorption in one case of non-PRP treated bone grafts at 6 months. In PRP group the compact bone was clearly differentiated from cancellous bone as in native bone and thick in five cases, thin in five cases. In non-PRP group the compact bone was thin as a whole. Comparing native bone group and PRP group the CT value of PRP treated bone graft was more or less close to native bone group and comparing native bone group and non-PRP group CT value was low in non-PRP treated bone graft. Whereas when comparing PRP and non-PRP group CT value was higher in PRP group. Autologous PRP was a safe, biocompatible, effective, source for growth factors and carries no risk of transmissible diseases. It enhances and accelerates bone regeneration of autogenous bone grafts.     

Effect of platelet-rich plasma on sinus lifting: a randomized-controlled clinical trial

Objective: The combination of anorganic bovine bone (ABB) with platelet‐rich plasma (PRP) has been widely used in bone regeneration procedures although its benefits are still unclear. The purpose of this study was to evaluate whether or not PRP improves the efficacy of ABB in sinus floor augmentation. In addition, we have investigated the effect of residual bone height and tobacco on implant survival in sinus augmentation procedures. Patient and Methods: Eighty‐seven patients recruited for this study underwent 144 sinus floor augmentation procedures using ABB alone or ABB plus PRP (ABB+PRP) in a randomized clinical trial. A total of 286 implants were placed in the augmented bone, and their evolution was followed up for a period of 24 months. In order to investigate on a histological level and any adjunctive effects, we performed an ancillary study in five edentulous patients with a symmetrical severely resorbed maxilla. In these patients, a bilateral sinus augmentation was randomly performed using ABB or ABB+PRP in a split‐mouth design, and after 6 months, bone biopsies were taken from the implant sites for histological and histomorphometric analysis. Results: Overall, 96.2% of ABB and 98.6% of ABB+PRP implant success were obtained during the monitoring period and differences were not found between sites grafted with and without PRP in the 87 patients studied. Densitometry assessments and graft resorption were similar in both experimental groups. However, the histological and histomorphometrical analysis in the five edentulous patients revealed that bone augmentation was significantly higher in sites treated with ABB+PRP (p0.05). Another outcome from our study is that the lack of initial bone support (p0.05) and smoking (p=0.05) appeared to have a negative effect on the treatment success, which was accentuated when both circumstances coincided. Conclusions: PRP is not a determining factor for implant survival in sinus lifting procedures. However, this study revealed that PRP can improve the osteoconductive properties of ABB by increasing the volume of new bone formed. Moreover, in sinus augmentation procedures the implant's survival rate appears to be more influenced by the residual bone height or by tobacco than by the type of bone graft.