Morphological and chemical analysis of bone substitutes by scanning electron microscopy and microanalysis by spectroscopy of dispersion energy.

Braz Dent J. 2007;18(2):129-33

Authors: Cruz GA, Toledo S, Sallum EA, Lima AF

This study evaluated the morphological and chemical composition of the following bone substitutes: cancellous and cortical organic bovine bone with macro and microparticle size ranging from 1.0 to 2.0 mm and 0.25 to 1.0 mm, respectively; inorganic bovine bone with particle size ranging from 0.25 to 1.0 mm; hydroxyapatite with particle size ranging from 0.75 to 1.0 mm; and demineralized freeze-dried bone allograft with particle size ranging from 0.25 to 0.5 mm. The samples were sputter-coated with gold in an ion coater, the morphology was observed and particle size was measured under vacuum by scanning electron microscopy (SEM). The chemical composition was evaluated by spectroscopy of dispersion energy (EDS) microanalysis using samples without coating. SEM analysis provided visual evidence that all examined materials have irregular shape and particle sizes larger than those informed by the manufacturer. EDS microanalysis detected the presence of sodium, calcium and phosphorus that are usual elements of the bone tissue. However, mineral elements were detected in all analyzed particles of organic bovine bone except for macro cancellous organic bovine bone. These results suggest that the examined organic bovine bone cannot be considered as a pure organic material.

PMID: 17982552 [PubMed - in process]

No positive effects of OP-1 device on the incorporation of impacted graft materials after 8 weeks: a bone chamber study in goats.

Acta Orthop. 2007 Aug;78(4):551-8

Authors: Hannink G, Schreurs BW, Buma P

BACKGROUND: Bone morphogenetic proteins (BMPs) have the potential to improve clinical outcome after hip revision surgery by improving graft incorporation and implant fixation. However, impaction of cancellous bone grafts and TCP/HA bone substitute mixed with OP-1 device in a bone chamber in goats in a previous study led to reduced fibrous tissue ingrowth after 4 weeks. New bone formation was not promoted by OP-1. In the current study we examined whether this reduction represented a final loss of ingrowth or was just a delay, and whether the reduction can be overcome and ultimately results in a better late ingrowth. METHODS: Bone chambers with impacted allografts and impacted TCP/HA granules mixed with 2 doses of OP-1 device were implanted in proximal medial goat tibias. Impacted allografts and TCP/HA not treated with OP-1 served as controls. After 8 weeks, the incorporation was evaluated using histology and histomorphometry. RESULTS: Histology revealed evidence of bone graft incorporation, which proceeded in a similar way in both allografts and TCP/HA, with and without the addition of OP-1. After 8 weeks, no difference in bone ingrowth was found between the OP-1 groups and their controls. It was only in the allografts that the addition of OP-1 resulted in more fibrous tissue ingrowth. INTERPRETATION: We conclude that the previously observed delay in fibrous tissue ingrowth can be only partially overcome.

PMID: 17966011 [PubMed - indexed for MEDLINE]

A comparative evaluation of the effectiveness of an anorganic bone matrix/cell binding peptide with an open flap debridement in human infrabony defects: a clinical and radiographic study.

J Contemp Dent Pract. 2007;8(6):25-34

Authors: Bhongade ML, Tiwari IR

AIM: The development of biologic modalities designed to enhance bone regeneration and wound healing of specific periodontal sites continues to unfold. This is accomplished through the cell binding activity of Type-I collagen provided by a synthetic cell binding peptide (P-15) which is incorporated in a scaffold of anorganic bovine matrix (ABM). This combination is designed to facilitate the attachment, migration, and differentiation of cells. The objective of this study is to clinically and radiographically evaluate the effectiveness of the combination of ABM and P-15 (ABM/P-15) 'putty' during regenerative periodontal procedures. METHODS AND MATERIALS: A total of 20 interproximal intraosseous defects in 16 patients, (8 males, 8 females), age 22-48 years (mean 34.45) were recruited and divided equally into two experimental groups. Following open flap debridement (OFD), the defect sites in a test group were grafted with a bovine-derived xenograft enriched with a cell binding peptide. The defect sites in a control group were treated with only OFD. Appropriate periodontal maintenance schedules were followed; at six months, clinical and radiographic assessments for soft tissue and hard tissue were performed for documentation and finalization of results. RESULTS: Statistical analysis using student paired 't' test analyses of the patient mean value from the 16 patients revealed the ABM/P-15 'putty' graft group demonstrated significantly better mean defect fill of 3.4 + 0.7 mm (70.5%) versus mean defect fill of 0.9 mm (17.33%) for defects treated with only OFD. Soft tissue findings showed significant differences among treatment with ABM/P-15 compared to OFD. CONCLUSIONS: These results indicate the use of P-15 synthetic cell binding peptide combined with ABM yields better clinical results in conjunction with OFD than with OFD alone.

PMID: 17846668 [PubMed - indexed for MEDLINE]

Bone formation with the combination of simvastatin and calcium sulfate in critical-sized rat calvarial defect.

J Pharmacol Sci. 2007 Aug;104(4):384-6

Authors: Nyan M, Sato D, Oda M, Machida T, Kobayashi H, Nakamura T, Kasugai S

Simvastatin, a cholesterol synthesis inhibitor, enhances BMP2 expression in osteoblasts. The purpose of the present study was to examine whether simvastatin stimulates bone regeneration when combined with calcium sulfate as a carrier. Critical-sized bone defects in rat calvaria were treated with calcium sulfate or with combination of 1 mg simvastatin and calcium sulfate. In the combination group, although the least amount of bone formation with intense soft tissue inflammation was observed at 2 and 4 weeks, remarkable bone formation was evident at 8 weeks. Conclusively, the combination of simvastatin and calcium sulfate stimulated bone regeneration in spite of the inflammatory response.

PMID: 17721043 [PubMed - indexed for MEDLINE]

[Regenerative medicine of bone and cartilage]

Nippon Ronen Igakkai Zasshi. 2007 Jan;44(1):69-71

Authors: Chung UI

PMID: 17337855 [PubMed - indexed for MEDLINE]

Animal models for implant biomaterial research in bone: a review.

Eur Cell Mater. 2007;13:1-10

Authors: Pearce AI, Richards RG, Milz S, Schneider E, Pearce SG

Development of an optimal interface between bone and orthopaedic and dental implants has taken place for many years. In order to determine whether a newly developed implant material conforms to the requirements of biocompatibility, mechanical stability and safety, it must undergo rigorous testing both in vitro and in vivo. Results from in vitro studies can be difficult to extrapolate to the in vivo situation. For this reason the use of animal models is often an essential step in the testing of orthopaedic and dental implants prior to clinical use in humans. This review discusses some of the more commonly available and frequently used animal models such as the dog, sheep, goat, pig and rabbit models for the evaluation of bone-implant interactions. Factors for consideration when choosing an animal model and implant design are discussed. Various bone specific features are discussed including the usage of the species, bone macrostructure and microstructure and bone composition and remodelling, with emphasis being placed on the similarity between the animal model and the human clinical situation. While the rabbit was the most commonly used of the species discussed in this review, it is clear that this species showed the least similarities to human bone. There were only minor differences in bone composition between the various species and humans. The pig demonstrated a good likeness with human bone however difficulties may be encountered in relation to their size and ease of handling. In this respect the dog and sheep/goat show more promise as animal models for the testing of bone implant materials. While no species fulfils all of the requirements of an ideal model, an understanding of the differences in bone architecture and remodelling between the species is likely to assist in the selection of a suitable species for a defined research question.

PMID: 17334975 [PubMed - indexed for MEDLINE]

Ectopic bone formation in cell-seeded poly(ethylene oxide)/poly(butylene terephthalate) copolymer scaffolds of varying porosity.

J Mater Sci Mater Med. 2007 Jul;18(7):1299-307

Authors: Claase MB, de Bruijn JD, Grijpma DW, Feijen J

Scaffolds from poly(ethylene oxide) and poly(butylene terephthalate), PEOT/PBT, with a PEO molecular weight of 1,000 and a PEOT content of 70 weight% (1000PEOT70PBT30) were prepared by leaching salt particles (425-500 microm). Scaffolds of 73.5, 80.6 and 85.0% porosity were treated with a CO(2) gas plasma and seeded with rat bone marrow stromal cells (BMSCs). After in vitro culture for 7 days (d) in an osteogenic medium the scaffolds were subcutaneously implanted for 4 weeks in nude mice. Poly(D, L-lactide) (PDLLA) and biphasic calcium phosphate (BCP) scaffolds were included as references. After 4 weeks (wks) all scaffolds showed ectopic formation of bone and bone marrow. For the scaffolds of different porosities, no significant differences were observed in the relative amounts of bone (7-9%) and bone marrow (6-11%) formed, even though micro computed tomography (mu-CT) data showed considerable differences in accessible pore volume and surface area. 1000PEOT70PBT30 scaffolds with a porosity of 85% could not maintain their original shape in vivo. Surprisingly, 1000PEOT70PBT30 scaffolds with a porosity of 73.5% showed cartilage formation. This cartilage formation is most likely due to poorly accessible pores in the scaffolds, as was observed in histological sections. mu-CT data showed a considerably smaller accessible pore volume (as a fraction of the total volume) than in 1000PEOT70PBT30 scaffolds of 80.6 and 85.0% porosity. BMSC seeded PDLLA (83.5% porosity) and BCP scaffolds (29% porosity) always showed considerably more bone and bone marrow formation (bone marrow formation is approximately 40%) and less fibrous tissue ingrowth than the 1000PEOT70PBT30 scaffolds. The scaffold material itself can be of great influence. In more hydrophobic and rigid scaffolds like the PDLLA or BCP scaffolds, the accessibility of the pore structure is more likely to be preserved under the prevailing physiological conditions than in the case of hydrophilic 1000PEOT70PBT30 scaffolds. Scaffolds prepared from other PEOT/PBT polymer compositions, might prove to be more suited.

PMID: 17268874 [PubMed - indexed for MEDLINE]

The influence of discharge power and heat treatment on calcium phosphate coatings prepared by RF magnetron sputtering deposition.

J Mater Sci Mater Med. 2007 Jun;18(6):1061-9

Authors: Yonggang Y, Wolke JG, Yubao L, Jansen JA

Ca-P coatings with different Ca/P ratio and composition were successfully prepared by RF magnetron sputtering deposition. The Ca/P ratio, phase composition, structure and morphological properties were characterized by XRD, FTIR, EDS and SEM analyses. All the as-sputtered coatings were amorphous and after IR-irradiation the coatings altered into a crystalline phase. The obtained coatings had a Ca/P ratio that varied from 0.55 to 2.10 and different phase compositions or mixtures of apatite, beta-pyrophosphate and beta-tricalciumphosphate structures were formed. Evidently, the phase compositions of the sputtered coatings are determined not only by the discharge power ratio of the hydroxylapatite and calcium pyrophosphate targets but also by the annealing temperature.

PMID: 17268873 [PubMed - indexed for MEDLINE]

Rat subcutaneous tissue response to macrogranular porous anorganic bovine bone graft.

Braz Dent J. 2006;17(4):274-8

Authors: Zambuzzi WF, Oliveira RC, Pereira FL, Cestari TM, Taga R, Granjeiro JM

The ideal bone graft must present biocompatibility, osteoconductive and osteoinductive properties, resistance and plasticity. Xenogenic grafts of bovine cancellous bone origin are particularly interesting due to their biologically designed porous structure that enhance both cellular and vascular invasion. The purpose of this study was to evaluate the tissue response induced by bovine macrogranular porous anorganic bone implanted in rat subcutaneous tissue. Forty rats were assigned to 2 groups, as follows: the control group received empty collagen capsules and the test group received subcutaneous implants of the test material. Samples were collected after 10, 20, 30 and 60 days and processed histologically. Histological analysis showed at 10 days a granulomatous inflammatory infiltrate, rich in multinucleated giant cells and free of lymphocytes or plasma cells, similarly to mineralized allograft implanted in rat subcutaneous. In later periods, there was a significant decrease in the inflammatory infiltrate and an increase in fibrosis around graft particles. In conclusion, the test material induced a foreign body-type granuloma with subsequent fibrosis around the graft particles implanted in rat subcutaneous and did not elicit any immune response, thus being considered biocompatible.

PMID: 17262138 [PubMed - indexed for MEDLINE]

Physico-chemical characterization and biocompatibility evaluation of hydroxyapatites.

J Oral Sci. 2006 Dec;48(4):219-26

Authors: da Cruz AC, Pochapski MT, Daher JB, da Silva JC, Pilatti GL, Santos FA

The aim of this study was to evaluate the physico-chemical and biocompatibility characteristics of two different hydroxyapatites. Physical and chemical properties were analyzed using granulometric analysis, scanning electron microscopy (SEM), X-ray energy-dispersion (EDX), X-ray fuorescence (XRF) and X-ray diffraction (XRD). Biomaterials were implanted into the subcutaneous tissue on the dorsum of 36 Wistar rats, divided into the following groups: Group 1 - Gen-Ox (natural); Group 2 - HA-U (synthetic) and Group 3 - Control (Sham). After 15 and 30 days, 6 animals/period were sacrificed and the subcutaneous tissue was taken for histological and histometric analysis, giving consideration to inflammatory reaction and granule area. The granulometric test results showed a mean granule diameter of 161.6 microm (min = 19.0 microm; max = 498.0 microm) and 48.7 microm (min = 7.0 microm; max = 256.0 microm) for groups 1 and 2 respectively. Analysis with SEM demonstrated irregular and sharp-edge particles in group 1 (3332.8 +/- 274.3 microm(2)) and irregular and rounded particles in group 2 (1320.8 +/- 83.0 microm(2)) (P < 0.0001; Student's t test). EDX and XRF revealed calcium, carbon, oxygen, sodium and phosphorus in both groups. XRD indicated that both biomaterials were pure and crystalline. There was a statistically significant difference in granule area between the two groups after 15 days (P = 0.022; Student's t-test). After 15 days, an increased inflammatory response was seen in group 2 (P < 0.0001; ANOVA and Tukey's post hoc test) whereas it was more pronounced in group 1 after 30 days (P < 0.0001; ANOVA and Tukey's post hoc test). It was concluded that these biomaterials have similar physical, chemical and biocompatibility characteristics.

PMID: 17220620 [PubMed - indexed for MEDLINE]

Biocompatibility of natural latex implanted into dental alveolus of rats.

J Oral Sci. 2006 Dec;48(4):201-5

Authors: Balabanian CA, Coutinho-Netto J, Lamano-Carvalho TL, Lacerda SA, Brentegani LG

The present study investigated the biocompatibility of a biopolymer based on vegetable latex extracted from the Hevea brasiliensis rubber tree, implanted into the bony alveolar cavity after dental extraction in rats. A granule of latex (area = 0.25 +/- 0.04 mm(2)) was implanted inside the alveolus immediately after extraction of the upper right incisor, and the animals were sacrificed 7, 21 and 42 days after the procedure. The hemi-maxillas were decalcified and processed for embedding in paraffin to obtain semi-serial longitudinal sections 5 mum thick, and then stained with hematoxylin-eosin. The latex granule was observed in the cervical third of the alveolus without any foreign body reaction, or persistence of the initial acute inflammatory reaction. Bone repair in the areas adjacent to the material was quantified, and a decrease was noted in the thickness of the fibrous capsule surrounding the implants from 92.8 +/- 9.3 microm on day 7 to 9.4 +/- 1.8 microm on day 42 (ANOVA, P = 0.01). The quantitative data confirmed acceleration of bone formation (statistically significant at 5%) in parallel with a decrease of connective tissue in the areas around the implants. These results show that the tested material is biologically compatible, and progressively integrated into the alveolar bone, simultaneously accelerating bone formation and playing an important role in the healing process.

PMID: 17220617 [PubMed - indexed for MEDLINE]

Posterolateral lumbar spinal fusion with autogenous bone chips from laminectomy extended with OsteoSet.

J Chin Med Assoc. 2006 Dec;69(12):581-4

Authors: Chen CL, Liu CL, Sun SS, Han PY, Lee CS, Lo WH

BACKGROUND: This study was conducted to evaluate posterolateral lumbar fusion with autogenous corticocancellous bone chips from the laminae and spinous processes extended with OsteoSet instead of cancellous bone from the iliac crest. METHODS: A total of 124 patients who underwent posterior decompression and posterolateral fusion with instrumentation between May 2001 and December 2003 were analyzed retrospectively. The study population comprised 49 males and 75 females with a mean age of 66 +/- 9.5 years. In all the patients, corticocancellous bone chips from laminectomy and OsteoSet were used as the graft material. There was no cancellous bone harvested from the iliac crest. The follow-up period was 28 +/- 7.1 months. RESULTS: The overall union rate was 91%, and the average union time was 3.9 months. There were 3 complications, including 2 patients with dura tear, and 1 with deep infection. At the final follow-up, the good and excellent results were up to 83.9%. CONCLUSION: Graft material from laminae and spinous processes extended with OsteoSet is reliable and effective enough to replace the graft from the posterior iliac crest.

PMID: 17182352 [PubMed - indexed for MEDLINE]

Injectable bone substitute to preserve alveolar ridge resorption after tooth extraction: a study in dog.

J Mater Sci Mater Med. 2006 Nov;17(11):1145-52

Authors: Boix D, Weiss P, Gauthier O, Guicheux J, Bouler JM, Pilet P, Daculsi G, Grimandi G

The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute on the prevention of alveolar ridge resorption after tooth extraction. Maxillary and mandibular premolars were extracted from 3 Beagle dogs with preservation of alveolar bone. Thereafter, distal sockets were filled with an injectable bone substitute (IBS), obtained by combining a polymer solution and granules of a biphasic calcium phosphate (BCP) ceramic. As a control, the mesial sockets were left unfilled. After a 3 months healing period, specimens were removed and prepared for histomorphometric evaluation with image analysis. Histomorphometric study allowed to measure the mean and the maximal heights of alveolar crest modifications. Results always showed an alveolar bone resorption in unfilled sockets. Resorption in filled maxillary sites was significantly lower than in control sites. Interestingly, an alveolar ridge augmentation was measured in mandibular filled sockets including 30% of newly-formed bone. It was concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate can significantly increase alveolar ridge preservation after tooth extraction.

PMID: 17122930 [PubMed - indexed for MEDLINE]

The bovine bone protein lyophilisate Colloss improves fixation of allografted implants--an experimental study in dogs.

Acta Orthop. 2006 Oct;77(5):791-8

Authors: Baas J, Lamberg A, Jensen TB, Elmengaard B, S&#xF8;balle K

BACKGROUND: Impacted morselized bone allograft is a well-established way of giving joint arthroplasties additional support in situations where there is insufficient bone stock. For long-term survival of the implant, early implant fixation is important. We hypothesized that Col-loss, a bone protein lyophilisate, might improve early implant fixation of allografted implants. METHOD: We inserted 4 porous-coated Ti implants in the distal femurs of 16 dogs. All implants were surrounded by a 2.5-mm gap, which was impacted with morselized allograft with or without Colloss. In each dog, the implants were treated with no Collos or low-, middle- or high-dose (0, 10, 20 and 40 mg) Colloss per cm3 allograft. The observation time was 4 weeks. RESULTS: Mechanical implant fixation was improved for all 3 groups with Colloss-treated implants (p < 0.05). The best anchorage was seen in the middle-dose group, where fixation was improved by 100%. We saw a dramatic reduction in fibrous tissue on the surface of the Colloss-treated implants (p < 0.001). The Colloss groups showed increased ongrowth of new bone (p < 0.01) and accelerated gap remodeling (p < 0.05). INTERPRETATION: Colloss can improve early osseointegration and fixation of allografted implants.

PMID: 17068713 [PubMed - indexed for MEDLINE]

Bioactive and bioresorbable cellular cubic-composite scaffolds for use in bone reconstruction.

J R Soc Interface. 2006 Dec 22;3(11):805-21

Authors: Shikinami Y, Okazaki K, Saito M, Okuno M, Hasegawa S, Tamura J, Fujibayashi S, Nakamura T

We used a novel composite fibre-precipitation method to create bioactive and bioresorbable cellular cubic composites containing calcium phosphate (CaP) particles (unsintered and uncalcined hydroxyapatite (u-HA), alpha-tricalcium phosphate, beta-tricalcium phosphate, tetracalcium phosphate, dicalcium phosphate dihydrate, dicalcium phosphate anhydrate or octacalcium phosphate) in a poly-D/L-lactide matrix. The CaP particles occupied greater than or equal to 70 wt% (greater than or equal to 50 vol%) fractions within the composites. The porosities of the cellular cubic composites were greater than or equal to 70% and interconnective pores accounted for greater than or equal to 70% of these values. In vitro changes in the cellular geometries and physical properties of the composites were evaluated over time. The Alamar Blue assay was used to measure osteoblast proliferation, while the alkaline phosphatase assay was used to measure osteoblast differentiation. Cellular cubic C-u-HA70, which contained 70 wt% u-HA particles in a 30 wt% poly-D/L-lactide matrix, showed the greatest three-dimensional cell affinity among the materials tested. This composite had similar compressive strength and cellular geometry to cancellous bone, could be modified intraoperatively (by trimming or heating) and was able to form cortico-cancellous bone-like hybrids. The osteoinductivity of C-u-HA70, independent of biological growth factors, was confirmed by implantation into the back muscles of beagles. Our results demonstrated that C-u-HA70 has the potential as a cell scaffold or temporary hard-tissue substitute for clinical use in bone reconstruction.

PMID: 17015297 [PubMed - indexed for MEDLINE]

Effect of platelet-rich plasma in the treatment of periodontal intrabony defects in humans.

Chin Med J (Engl). 2006 Sep 20;119(18):1511-21

Authors: Ouyang XY, Qiao J

BACKGROUND: Platelet-rich plasma (PRP) is a kind of natural source of autologous growth factors, and has been used successfully in medical community. However, the effect of PRP in periodontal regeneration is not clear yet. This study was designed to evaluate the effectiveness of PRP as an adjunct to bovine porous bone mineral (BPBM) graft in the treatment of human intrabony defects. METHODS: Seventeen intrabony defects in 10 periodontitis patients were randomly treated either with PRP and BPBM (test group, n = 9) or with BPBM alone (control group, n = 8). Clinical parameters were evaluated including changes in probing depth, relative attachment level (measured by Florida Probe and a stent), and bone probing level between baseline and 1 year postoperatively. Standardized periapical radiographs of each defect were taken at baseline, 2 weeks, and 1 year postoperatively, and analyzed by digital subtraction radiography (DSR). RESULTS: Both treatment modalities resulted in significant attachment gain, reduction of probing depth, and bone probing level at 1-year post-surgery compared to baseline. The test group exhibited statistically significant improvement compared to the control sites in probing depth reduction: (4.78 +/- 0.95) mm versus (3.48 +/- 0.41) mm (P < 0.01); clinical attachment gain: (4.52 +/- 1.14) mm versus (2.85 +/- 0.80) mm (P < 0.01); bone probing reduction: (4.56 +/- 1.04) mm versus (2.88 +/- 0.79) mm (P < 0.01); and defect bone fill: (73.41 +/- 14.78)% versus (47.32 +/- 11.47)% (P < 0.01). DSR analysis of baseline and 1 year postoperatively also showed greater radiographic gains in alveolar bone mass in the test group than in the control group: gray increase (580 +/- 50) grays versus (220 +/- 32) grays (P = 0.0001); area with increased gray were (5.21 +/- 1.25) mm(2) versus (3.02 +/- 1.22) mm(2) (P = 0.0001). CONCLUSIONS: The treatment with a combination of PRP and BPBM led to a significantly favorable clinical improvement in periodontal intrabony defects compared to using BPBM alone. Further studies are necessary to assess the long-term effectiveness of PRP, and a larger sample size is needed.

PMID: 16996004 [PubMed - indexed for MEDLINE]

Evaluation of processed bovine cancellous bone matrix seeded with syngenic osteoblasts in a critical size calvarial defect rat model.

J Cell Mol Med. 2006 Jul-Sep;10(3):695-707

Authors: Kneser U, Stangenberg L, Ohnolz J, Buettner O, Stern-Straeter J, M&#xF6;best D, Horch RE, Stark GB, Schaefer DJ

INTRODUCTION: Biologic bone substitutes may offer alternatives to bone grafting procedures. The aim of this study was to evaluate a preformed bone substitute based on processed bovine cancellous bone (PBCB) with or without osteogenic cells in a critical size calvarial defect rat model. METHODS: Discs of PBCB (Tutobone) were seeded with second passage fibrin gel-immobilized syngenic osteoblasts (group A, n = 40). Cell-free matrices (group B, n = 28) and untreated defects (group C; n=28) served as controls. Specimens were explanted between day 0 and 4 months after implantation and were subjected to histological and morphometric evaluation. RESULTS: At 1 month, bone formation was limited to small peripheral areas. At 2 and 4 months, significant bone formation, matrix resorption as well as integration of the implants was evident in groups A and B. In group C no significant regeneration of the defects was observed. Morphometric analysis did not disclose differences in bone formation in matrices from groups A and B. Carboxyfluorescine-Diacetate-Succinimidylester (CFDA) labeling demonstrated low survival rates of transplanted cells. DISCUSSION: Osteoblasts seeded into PBCB matrix display a differentiated phenotype following a 14 days cell culture period. Lack of initial vascularization may explain the absence of added osteogenicity in constructs from group A in comparison to group B. PBCB is well integrated and represents even without osteogenic cells a promising biomaterial for reconstruction of critical size calvarial bone defects.

PMID: 16989729 [PubMed - indexed for MEDLINE]

Morphology of autogenous bone graft and castor oil polyurethane in the infraorbital rim of rabbits: a comparative study.

Acta Cir Bras. 2006 Sep-Oct;21(5):341-7

Authors: Mendonça JC, De Rossi R, Inouye CM, Bazan DR, Monteiro JC, Mendonça JP

PURPOSE: Morphological study comparing castor oil polyurethane and autogenous bone graft to repair bone defect in zygomatic bone of rabbits. METHODS: Twenty-four adult, male New Zealand rabbits were randomly distributed between two groups of twelve. Bone defects of 5mm in diameter were cut through the zygomatic bone and filled with polyurethane discs in the experimental group or autogenous bone harvested from the tibia in the control group. Animals were sacrificed after 30, 60 or 90 days, and the zygomatic bones were macro- and microscopically analyzed. Student's, Fisher's, chi-squared and McNemar's tests were used for statistical analysis. RESULTS: Both the castor oil polyurethane and the autograft adapted well to the defect, with no need for fixation. Fibrous connective tissue encapsulated the polyurethane, but no inflammation or giant cell reaction was observed. Acidophilic and basophilic areas were observed inside the micropores of the polyurethane, suggesting cell nuclei. After 90 days, bone repair with a lamellar pattern of organization was observed in the control group. CONCLUSION: The castor oil polyurethane was biocompatible and did not cause inflammation. It may be considered an alternative to fill bone defects.

PMID: 16981039 [PubMed - indexed for MEDLINE]

[Defect repair in rat mandible with hydroxyapatite cement compared to small intestine submucosa]

Rev Bras Otorrinolaringol (Engl Ed). 2006 Mar-Apr;72(2):195-9

Authors: Soccol AT, Bettega S, Noronha L, Sass S, Soccol VT, Scholz MR, Mocellin M

AIM: The aim of this study was to evaluate the bone formation in surgically created defects of rabbit mandibles by synthetic hydroxyapatite of calcium compared to small Intestine Submucosa. MATERIAL AND METHOD: 24 mice lineage Wisthar-Furth were used. A bony defect of 0,75 cm x 1,5 cm in mandibular ramus was accomplished in all animals. The hydroxyapatite implants were placed on the left hemimandiblein group I, small Intestine submucosa in group II, and the right served as control. The euthanasia was accomplished in the 40 degrees postoperative day, it was proceeded the macroscopic and histological analysis. RESULTS: medium length in millimeters of the hemimandibless in the hydroxyapatite group was of 3,75, in the small intestine submucosa 3,03 and the control group was of 2,63 (p: 0,022). Histomorphometry study revealed new bone grown in 76,64% of the total area in hydroxyapatite group (p: 0,022). In Small Intestinal submucosa group new bone grown in 63,64% do total (p: 0,0022). DISCUSSION: satisfactory bone integration was observed of the synthetic hydroxyapatite in that experimental model. Small intestinal submucosa cause osteoinduction CONCLUSION: using hydroxyapatite of calcium resulted in formation of significantly larger volume fractions of new bone when compared to small intestinal submucosa group.

PMID: 16951852 [PubMed - indexed for MEDLINE]

An animal model in sheep for biocompatibility testing of biomaterials in cancellous bones.

BMC Musculoskelet Disord. 2006;7:67

Authors: Nuss KM, Auer JA, Boos A, von Rechenberg B

BACKGROUND: The past years have seen the development of many synthetic bone replacements. To test their biocompatibility and ability for osseointegration, osseoinduction and -conduction requires their placement within bone preferably in an animal experiment of a higher species. METHODS: A suitable experimental animal model in sheep with drill holes of 8 mm diameter and 13 mm depth within the proximal and distal humerus and femur for testing biocompatibility issues is introduced. RESULTS: This present sheep model allows the placing of up to 8 different test materials within one animal and because of the standardization of the bone defect, routine evaluation by means of histomorphometry is easily conducted. This method was used successfully in 66 White Alpine Sheep. When the drill holes were correctly placed no complications such as spontaneous fractures were encountered. CONCLUSION: This experimental animal model serves an excellent basis for testing the biocompatibility of novel biomaterials to be used as bone replacement or new bone formation enhancing materials.

PMID: 16911787 [PubMed - indexed for MEDLINE]

Development of a nonrigid, durable calcium phosphate cement for use in periodontal bone repair.

J Am Dent Assoc. 2006 Aug;137(8):1131-8

Authors: Xu HH, Takagi S, Sun L, Hussain L, Chow LC, Guthrie WF, Yen JH

BACKGROUND: Calcium phosphate cement (CPC) hardens in situ to form hydroxyapatite and has been used in dental and craniofacial restorative applications. However, when CPC was used in periodontal osseous repair, tooth mobility resulted in the fracture and exfoliation of the brittle CPC implant. The objective of the authors' study was to develop a strong and nonrigid CPC to provide compliance for tooth mobility without fracturing the implant. METHODS: The authors used tetracalcium phosphate, dicalcium phosphate anhydrous and biopolymer chitosan to develop a strong and nonrigid CPC. They used a powder:liquid ratio of 2:1, compared with the 1:1 ratio of a previously developed nonrigid CPC control. Specimens were characterized using a flexural test, scanning electron microscopy and powder X-ray diffraction. RESULTS: After 28 days of immersion, the new cement had a flexural strength (mean +/- standard deviation; n = 6) of 5.2 +/- 1.0 megapascals, higher than 1.8 +/- 1.5 MPa for the control (P < .05) and overlapping the reported strengths of sintered hydroxyapatite implants and cancellous bone. This cement showed a high ductility with a strain at peak load of 6.5 +/- 1.3 percent, compared with 4.4 +/- 1.9 percent for the control; both were 20-fold higher than the 0.2 percent of the conventional CPC. Nanosized hydroxyapatite crystals, similar to those in teeth and bones, were formed in the cements. CONCLUSIONS: The new nonrigid cement, containing nanohydroxyapatite crystals, possessed a high ductility and superior fracture resistance. This strong, tough and nonrigid CPC may be useful in periodontal repair to provide compliance for tooth mobility without fracture. CLINICAL IMPLICATIONS: The results of this study may yield the first self-hardening and nonrigid hydroxyapatite composite with high strength and durability and large deformation capability to be useful in the regeneration of periodontal osseous defects.

PMID: 16873330 [PubMed - indexed for MEDLINE]

Heterogeneous nucleation of hydroxyapatite on protein: structural effect of silk sericin.

J R Soc Interface. 2005 Sep 22;2(4):373-8

Authors: Takeuchi A, Ohtsuki C, Miyazaki T, Kamitakahara M, Ogata S, Yamazaki M, Furutani Y, Kinoshita H, Tanihara M

Acidic proteins play an important role during mineral formation in biological systems, but the mechanism of mineral formation is far from understood. In this paper, we report on the relationship between the structure of a protein and hydroxyapatite deposition under biomimetic conditions. Sericin, a type of silk protein, was adopted as a suitable protein for studying structural effect on hydroxyapatite deposition, since it forms a hydroxyapatite layer on its surface in a metastable calcium phosphate solution, and its structure has been reported. Sericin effectively induced hydroxyapatite nucleation when it has high molecular weight and a beta sheet structure. This indicates that the specific structure of a protein can effectively induce heterogeneous nucleation of hydroxyapatite in a biomimetic solution, i.e. a metastable calcium phosphate solution. This finding is useful in understanding biomineralization, as well as for the design of organic polymers that can effectively induce hydroxyapatite nucleation.

PMID: 16849195 [PubMed - indexed for MEDLINE]

The mechanism of biomineralization of bone-like apatite on synthetic hydroxyapatite: an in vitro assessment.

J R Soc Interface. 2004 Nov 22;1(1):17-22

Authors: Kim HM, Himeno T, Kawashita M, Kokubo T, Nakamura T

The mechanism of biomineralization of bone-like apatite on synthetic hydroxyapatite (HA) has been investigated in vitro, in which the HA surface was surveyed as a function of soaking time in simulated body fluid (SBF). In terms of surface structure by transmission electron microscopy with energy-dispersive X-ray spectrometry, the HA whose Ca/P atomic ratio was 1.67 revealed three different characteristic soaking periods in SBF, i.e. the first soaking period, in which the HA surface increased the Ca/P ratio up to 1.83 to form an amorphous phase of Ca-rich calcium phosphate; the second soaking period, in which the HA surface decreased the Ca/P ratio up to 1.47 to form an amorphous phase of Ca-poor calcium phosphate; and the third soaking period, in which the HA surface gradually increased the Ca/P ratio up to 1.65 to eventually produce the bone-like nano-cerystallites of apatite, which grew forming complex crystal assemblies with a further increase in immersion time. Analysis using electrophoresis spectroscopy indicated that, immediately after immersion in SBF, the HA revealed a highly negative surface potential, which increased to reach a maximum positive value in the first soaking period. The surface potential then decreased to again reach a negative value in the second soaking period and thereafter converge to a constant negative value in the third soaking period. This implies that the HA induces biomineralization of apatite by smartly varying its surface potential to trigger an electrostatic interaction, first with positive calcium ions and second with negative phosphate ions in the SBF.

PMID: 16849149 [PubMed - indexed for MEDLINE]

First histological observations on the incorporation of a novel nanocrystalline hydroxyapatite paste OSTIM in human cancellous bone.

BMC Musculoskelet Disord. 2006;7:50

Authors: Huber FX, Belyaev O, Hillmeier J, Kock HJ, Huber C, Meeder PJ, Berger I

BACKGROUND: A commercially available nanocrystalline hydroxyapatite paste Ostim has been reported in few recent studies to surpass other synthetic bone substitutes with respect to the observed clinical results. However, the integration of this implantable material has been histologically evaluated only in animal experimental models up to now. This study aimed to evaluate the tissue incorporation of Ostim in human cancellous bone after reconstructive bone surgery for trauma. METHODS: Biopsy specimens from 6 adult patients with a total of 7 tibial, calcaneal or distal radial fractures were obtained at the time of osteosynthesis removal. The median interval from initial operation to tissue sampling was 13 (range 3-15) months. Samples were stained with Masson-Goldner, von Kossa, and toluidine blue. Osteoid volume, trabecular width and bone volume, and cortical porosity were analyzed. Samples were immunolabeled with antibodies against CD68, CD56 and human prolyl 4-hydroxylase to detect macrophages, osteoblasts, and fibroblasts, respectively. TRAP stainings were used to identify osteoclasts. RESULTS: Histomorphometric data indicated good regeneration with normal bone turnover: mean osteoid volume was 1.93% of the trabecular bone mass, trabecular bone volume--28.4%, trabecular width--225.12 microm, and porosity index--2.6%. Cortical and spongious bone tissue were well structured. Neither inflammatory reaction, nor osteofibrosis or osteonecrosis were observed. The implanted material was widely absorbed. CONCLUSION: The studied nanocrystalline hydroxyapatite paste showed good tissue incorporation. It is highly biocompatible and appears to be a suitable bone substitute for juxtaarticular comminuted fractures in combination with a stable screw-plate osteosynthesis.

PMID: 16762071 [PubMed - indexed for MEDLINE]

Comparison the cytotoxicity of hydroxyapatite measured by direct cell counting and MTT test in murine fibroblast NIH-3T3 cells.

Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2005 Dec;149(2):393-6

Authors: Theiszov&#xE1; M, Jantová S, Dragúnová J, Grznárová P, Palou M

The worldwide growing interest to biomaterials over the last years results from their irreplaceable role in medical clinic. Hydroxyapatite is used in bone reconstruction because of its similar chemical structure compared to the inorganic composition of human bone and it is basic building component of many newly prepared biomaterials. In this study, we evaluated cytotoxic/antiproliferative activity of hydroxyapatite extract using murine fibroblast cell line NIH-3T3 and two in vitro different cytotoxic assays: growth inhibition assay and MTT assay. Hydroxyapatite extract after 72 h of incubation manifested the significant in vitro cytotoxic/antiproliferative effect only at the highest concentration tested (100 %). The antiproliferative effect of hydroxyapatite extract at the other concentrations tested (75 %, 50 %, 25 %, 10 %, 5 % and 1 %) was directly proportional to the concentration and the time of influence. The inhibition of cell proliferation was 86.8 - 0 %. The sensitivity of cell growth inhibition assay (direct counting of viable cells) to the extract influence was higher than that of MTT test.

PMID: 16601796 [PubMed - indexed for MEDLINE]

Collagen-hydroxyapatite composites for hard tissue repair.

Eur Cell Mater. 2006;11:43-56

Authors: Wahl DA, Czernuszka JT

Bone is the most implanted tissue after blood. The major solid components of human bone are collagen (a natural polymer, also found in skin and tendons) and a substituted hydroxyapatite (a natural ceramic, also found in teeth). Although these two components when used separately provide a relatively successful mean of augmenting bone growth, the composite of the two natural materials exceeds this success. This paper provides a review of the most common routes to the fabrication of collagen (Col) and hydroxyapatite (HA) composites for bone analogues. The regeneration of diseased or fractured bones is the challenge faced by current technologies in tissue engineering. Hydroxyapatite and collagen composites (Col-HA) have the potential in mimicking and replacing skeletal bones. Both in vivo and in vitro studies show the importance of collagen type, mineralisation conditions, porosity, manufacturing conditions and crosslinking. The results outlined on mechanical properties, cell culturing and de-novo bone growth of these devices relate to the efficiency of these to be used as future bone implants. Solid free form fabrication where a mould can be built up layer by layer, providing shape and internal vascularisation may provide an improved method of creating composite structures.

PMID: 16568401 [PubMed - indexed for MEDLINE]

Effects of a hydroxyapatite-based biomaterial on gene expression in osteoblast-like cells.

J Dent Res. 2006 Apr;85(4):354-8

Authors: Sibilla P, Sereni A, Aguiari G, Banzi M, Manzati E, Mischiati C, Trombelli L, del Senno L

Biostite is a hydroxyapatite-derived biomaterial that is used in periodontal and bone reconstructive procedures due to its osteoconductive properties. Since the molecular effects of this biomaterial on osteoblasts are still unknown, we decided to assess whether it may specifically modulate osteoblast functions in vitro. We found that a brief exposure to Biostite significantly reduced the proliferation of MG-63 and SaOS-2 osteoblast-like cells to approximately 50% of the plateau value. Furthermore, gene array analysis of MG-63 cells showed that Biostite caused a differential expression of 37 genes which are involved in cell proliferation and interaction, and related to osteoblast differentiation and tissue regeneration. Results were confirmed by RT-PCR, Western blot, and by an increase in alkaline phosphatase (ALP) specific activity. Biostite also increased levels of polycystin-2, a mechano-sensitive Ca(2+) channel, a promising new marker of bone cell differentiation. Biostite, therefore, may directly affect osteoblasts by enhancing chondro/osteogenic gene expression and cytoskeleton-related signaling pathways, which may contribute to its clinical efficacy.

PMID: 16567558 [PubMed - indexed for MEDLINE]

Imaging characteristics of bone graft materials.

Radiographics. 2006 Mar-Apr;26(2):373-88

Authors: Beaman FD, Bancroft LW, Peterson JJ, Kransdorf MJ, Menke DM, DeOrio JK

Bone graft materials are widely used in reconstructive orthopedic procedures to promote new bone formation and bone healing, provide a substrate and scaffolding for development of bone structure, and function as a means for direct antibiotic delivery. Bone graft materials include autografts, allografts, and synthetic substitutes. An autograft (from the patient's own bone) supplies both bone volume and osteogenic cells capable of new bone formation. The imaging appearance of an autograft depends on its type, composition, and age. Autografts often appear as osseous fragments at radiography. At computed tomography (CT), autografts appear similar to the adjacent cortical bone. At magnetic resonance (MR) imaging, however, autografts have a variable appearance as a consequence of the viable marrow inside them, a feature not present in other graft materials. An allograft (from cadaveric bone) has an appearance similar to that of cortical bone on radiographs and CT images. An allograft in the form of bone chips or morsels does not show those features on radiographs and CT images, but instead appears as a conglomerate with medium to high opacity and attenuation within the bone defect. In the immediate postoperative period, allografts appear hypointense on both T1- and T2-weighted MR images. Hematopoietic tissue replaces the normal fatty marrow in the later phases of graft incorporation. Synthetic bone substitutes are much more variable in imaging appearance. As the use of bone allografts and synthetic substitutes increases, familiarity with postoperative imaging features is essential for differentiation between grafts and residual or recurrent disease.

PMID: 16549604 [PubMed - indexed for MEDLINE]

[Repair of mandibular central fissures in rabbits with hBMP-2 gene modified tissue engineered bone]

Shanghai Kou Qiang Yi Xue. 2006 Feb;15(1):42-7

Authors: Ye ZC, Wei FC, Wang KT, Sun SZ, Zhao HQ, Li GJ

PURPOSE: To evaluate the effectiveness of the tissue engineered bone substitute loaded with periosteal-derived osteoblasts (POBs) transfected by adenovirus mediated human bone morphogenetic protein-2 gene (Ad-hBMP-2) in the repair of rabbit mandibular central fissures. METHODS: 45 rabbits with the soft tissue in the mandibular central fissures removed were randomly divided into 5 groups, group I: Ad-hBMP-2 transfected POBs/bioglass group (n=10); group II: adenovirus mediated enhanced green fluorescent protein (Ad-EGFP) gene transfected POBs/bioglass group (n=10); group III: untransfected POBs/bioglass group (n=10); group IV: single bioglass group (n=10); group V: control group (n=5). The above bone substitutes were implanted in the rabbit mandibular central fissures respectively except group V. The samples were studied by gross, X-ray, histomorphology, histomorphometrical analysis and biomechanics after 2, 4, 8, 12 weeks respectively. One-way ANOVA was used for statistical analysis. RESULTS: In gross view, the rabbit mandibular central fissures in group I were replaced by new bone including cortical bone from the 4th week. X-ray examination showed that the higher bone density was found in the rabbit mandibular central fissures of group I 4 to 8 weeks after implantation. Histomorphometrical analysis showed much more new bony callus in group I than in other groups (P<0.01). The maximal anti-bending load and bending rigidity of the implanted bone substitute of group I were significantly higher than those of group II, III and IV (P<0.01). CONCLUSION: The tissue engineered bone substitute loaded with POBs transfected by human BMP-2 gene could get the best result in the repair of rabbit mandibular central fissures, therefore, it is likely to be used in the repair of alveolar clefts.

PMID: 16525608 [PubMed - in process]

In vitro gentamicin release from commercially available calcium-phosphate bone substitutes influence of carrier type on duration of the release profile.

BMC Musculoskelet Disord. 2006;7:18

Authors: Stallmann HP, Faber C, Bronckers AL, Nieuw Amerongen AV, Wuisman PI

BACKGROUND: Polymethyl-methacrylate (PMMA) beads releasing antibiotics are used extensively to treat osteomyelitis, but require surgical removal afterwards because they do not degrade. METHODS: As an alternative option, this report compares the in vitro gentamicin release profile from clinically used, biodegradable carrier-materials: six injectable cements and six granule-types. Cement cylinders and coated granules containing 3% gentamicin were submerged in dH2O and placed in a 48-sample parallel drug-release system. At regular intervals (30, 90, 180 min. and then every 24 h, for 21 days), the release fluid was exchanged and the gentamicin concentration was measured. The activity of released gentamicin was tested on Staphylococcus aureus. RESULTS: All combinations showed initial burst-release of active gentamicin, two cements had continuous-release (17 days). The relative release of all cements (36-85%) and granules (30-62%) was higher than previously reported for injectable PMMA-cements (up to 17%) and comparable to other biodegradable carriers. From the cements residual gentamicin could be extracted, whereas the granules released all gentamicin that had adhered to the surface. CONCLUSION: The high release achieved shows great promise for clinical application of these biodegradable drug-carriers. Using the appropriate combination, the required release profile (burst or sustained) may be achieved.

PMID: 16504140 [PubMed - indexed for MEDLINE]

Maxillary myxoma: surgical treatment and reconstruction with buccal fat pad flap: a case report.

J Contemp Dent Pract. 2006 Feb 15;7(1):107-16

Authors: Og&#xFC;tcen-Toller M, Sener I, Kasap V, Cakir-Ozkan N

Myxoma is a benign tumor that arises from mesenchymal tissue and is found less commonly in the bone than in soft tissue. The majority of bony myxomas occur in the jaws. When compared with other odontogenic tumors, myxoma of the jaws is a rare entity. Numerous types of treatment have been used for these tumors including simple curettage, enucleation, curettage with peripheral ostectomy, and en bloc resection with or without immediate reconstruction. The buccal fat pad (BFP) is a lobulated mass of fatty tissue in the oromaxillofacial region, which has long been a source of grafts in facial augmentation. A case of an odontogenic myxoma in the left maxillary molar area of a 34-year-old female that was treated by curettage and peripheral ostectomy is presented. The surgical defect was successfully repaired with a pedicled BFP flap.

PMID: 16491153 [PubMed - indexed for MEDLINE]

A clinical evaluation of anorganic bovine bone graft plus 10% collagen with or without a barrier in the treatment of class II furcation defects.

J Contemp Dent Pract. 2006 Feb 15;7(1):60-70

Authors: Reddy KP, Nayak DG, Uppoor AS

The use of bone replacement grafts with barrier membranes in class II furcation defects are aimed at improving the outcome of the regenerative technique. In this regard, however, there is a paucity of studies comparing the results obtained with bone grafts alone or in combination with barrier membranes. The aim of this study was to clinically compare an anorganic bovine bone graft plus 10% collagen (BO) with or without a bioresorbable collagen barrier (BG) in human mandibular molar class II furcation defects. METHODS AND MATERIALS: Twenty mandibular class II furcation defects (ten patients with bilateral defects) were treated either with BO (group I) or a combination of BO/BG (group II). Each defect was randomly assigned to either group I or group II. The soft tissue and hard tissue measurements including vertical probing depth (VPD), horizontal probing depth (HPD), clinical attachment level (CAL), gingival recession (GR), vertical depth of furcation defect (VDF), and horizontal depth of furcation defect (HDF) were recorded at baseline and six months after surgery. RESULTS: Both treatment procedures resulted in statistically significant reduction in VPD and HPD, gain in CAL, and reduction in VDF and HDF. There was a statistically significant difference between group I and group II in all soft and hard tissue parameters with the exception of VPD reduction and gingival recession. CONCLUSION: The findings of this study suggest superior clinical results with BO/BG treatment when compared to BO treatment in mandibular class II furcation defects.

PMID: 16491148 [PubMed - indexed for MEDLINE]

Freezing as a path to build complex composites.

Science. 2006 Jan 27;311(5760):515-8

Authors: Deville S, Saiz E, Nalla RK, Tomsia AP

Materials that are strong, ultralightweight, and tough are in demand for a range of applications, requiring architectures and components carefully designed from the micrometer down to the nanometer scale. Nacre, a structure found in many molluscan shells, and bone are frequently used as examples for how nature achieves this through hybrid organic-inorganic composites. Unfortunately, it has proven extremely difficult to transcribe nacre-like clever designs into synthetic materials, partly because their intricate structures need to be replicated at several length scales. We demonstrate how the physics of ice formation can be used to develop sophisticated porous and layered-hybrid materials, including artificial bone, ceramic-metal composites, and porous scaffolds for osseous tissue regeneration with strengths up to four times higher than those of materials currently used for implantation.

PMID: 16439659 [PubMed - indexed for MEDLINE]

The role of heparan sulfate and perlecan in bone-regenerative procedures.

J Dent Res. 2006 Feb;85(2):122-32

Authors: DeCarlo AA, Whitelock JM

Tissue engineering, grafting procedures, regeneration, and tissue remodeling are developing therapeutic modalities with great potential medical value, but these regenerative modalities are not as effective or predictable as clinicians and patients would like. Greater understanding of growth factors, cytokines, extracellular matrix molecules, and their roles in cell-mediated healing processes have made these regenerative therapies more clinically viable and will continue advancing the fields of tissue engineering and grafting. However, millions of oral and non-oral bone-grafting procedures are performed annually, and only a small percentage yield the most desirable results. Here we review the heparan-sulfate-decorated extracellular biomolecule named perlecan and the research relating to its potential as an adjunct in bone-regenerative procedures. The review includes an overview of bone graft substitutes and biological adjuncts to bone-regenerative procedures in medicine as they apply to periodontal disease, alveolar ridge augmentation, and barrier membrane therapy. Perlecan is discussed as a potential biological adjunct in terms of growth factor sequestration and delivery, and promoting cell adhesion, proliferation, differentiation, and angiogenesis. Further, we propose delivery and application schemes for perlecan and/or its domains in bone-regenerative procedures, with particular emphasis on its heparan-sulfate-decorated domain I. The perlecan molecule, with its heparan sulfate glycosylation, may provide a multi-faceted approach for the delivery of a more comprehensive stimulus than other single potential adjuncts currently available for bone-regenerative procedures.

PMID: 16434729 [PubMed - indexed for MEDLINE]

[Bone defect repair with a new tissue-engineered bone carrying bone morphogenetic protein in rabbits]

Di Yi Jun Yi Da Xue Xue Bao. 2005 Nov;25(11):1369-74

Authors: Hu JJ, Jin D, Quan DP, Zhong SZ, Chen JH, Wei KH, Zhao J, Pei GX

OBJECTIVE: To construct a new tissue-engineered bone with poly (D, L-lactide-co-glycolide) (PLGA), bone morphogenetic protein (BMP) and bone marrow-derived stem cells (BMSCs) and observe its effect in repairing segmental bone defects. METHODS: A 15-mm bone defect in the right radius was induced in New Zealand white rabbits, and the models were randomized into three groups to receive implantation of the tissue-engineered bone grafts constructed with PLGA carrying 5 mg BMP and about 1 x 10(6) BMSCs (experimental group), grafts of PLGA with about 1 x 10(6) BMSCs (control group), or grafts of exclusive PLGA (blank control group), respectively. The osteogenesis in the bone defect after the implantation on was evaluated X-ray films, and the histological changes of the tissues sampled from the bone defect 4, 8, and 12 weeks after operation were observed and new bone formation was measured by image analysis. RESULTS: The bone defect was completely repaired in the experimental group 12 weeks after the implantation, showing the best results among the 3 groups. The bone defects in the blank control group was filled with only fibrous and connective tissues at 12 weeks. CONCLUSION: This tissue-engineered bone constructed with PLGA, BMP and BMSCs possesses good ability in repairing segmental bone defect.

PMID: 16305958 [PubMed - indexed for MEDLINE]

Retention of maxillary molars with Class III furcation involvement utilizing glass-ionomer: two case reports.

J Contemp Dent Pract. 2005 Nov 15;6(4):160-7

Authors: Reddy KP, Nayak DG, Uppoor AS

Advanced furcation invasion has long been a treatment dilemma for the clinician. The present two case reports used a glass ionomer restorative material as a barrier in the treatment of maxillary Class III furcation defects. One year follow-up results showed a reduction in tooth mobility and probing depths and no bleeding on probing with the use of the glass ionomer. These case reports offer another option in the treatment of a seemingly hopeless periodontally involved maxillary molar.

PMID: 16299618 [PubMed - indexed for MEDLINE]

Resorption of apatite-wollastonite containing glass-ceramic and beta-tricalcium phosphate in vivo.

Acta Med Okayama. 2005 Oct;59(5):201-7

Authors: Teramoto H, Kawai A, Sugihara S, Yoshida A, Inoue H

Apatite-wollastonite containing glass ceramic is considered to be difficult to resorb, but we experienced the disappearance of the porous type of Apatite-wollastonite glass ceramic particles . In this study, the resorption of porous apatite-wollastonite glass-ceramic implanted in the femurs of rabbits was investigated, and the process was compared with beta-tricalcium phosphate, a resorbable ceramics. Porous apatite-wollastonite glass-ceramic (70, 80, and 90% porosity) and beta-tricalcium phosphate (75% porosity) were implanted in the femurs of Japanese white rabbits. Samples were harvested and examined 0, 4, 8, 12, 24 and 36 weeks after implantation. Quantitative analysis of the radiographic and histologic findings was performed with NIH Image software. Radiographic examination demonstrated that the radiopacity and size of the porous apatite-wollastonite glassceramic cylinders decreased gradually after implantation. Histologic examination revealed that the surface area of the apatite-wollastonite glass-ceramic cylinders decreased continuously, and approached 20% of the original area 36 weeks after implantation. However, the resorption rate of porous apatite-wollastonite glass-ceramic was slower than that of beta-tricalcium phosphate. Toluidine blue staining showed abundant new bone formation on the surface of the apatite-wollastonite glassceramic matrix. Considering its mechanical strength, gradual resorption characteristics, and good osteochonductive activity, porous apatite-wollastonite glass-ceramic appears to be a suitable artificial bone substitutes.

PMID: 16286959 [PubMed - indexed for MEDLINE]

Osteoblast response to zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate.

J Biomed Mater Res A. 2006 Mar 1;76(3):596-604

Authors: Whited BM, Skrtic D, Love BJ, Goldstein AS

Calcium phosphate bioceramics, such as hydroxyapatite, have long been used as bone substitutes because of their proven biocompatibility and bone binding properties in vivo. Recently, a zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate (Zr-ACP) has been synthesized, which is more soluble than hydroxyapatite and allows for controlled release of calcium and phosphate ions. These ions have been postulated to increase osteoblast differentiation and mineralization in vitro. The focus of this work is to elucidate the physicochemical properties of Zr-ACP and to measure cell response to Zr-ACP in vitro using a MC3T3-E1 mouse calvarial-derived osteoprogenitor cell line. Cells were cultured in osteogenic medium and mineral was added to culture at different stages in cell maturation. Culture in the presence of Zr-ACP showed significant increases in cell proliferation, alkaline phosphatase activity (ALP), and osteopontin (OPN) synthesis, whereas collagen synthesis was unaffected. In addition, calcium and phosphate ion concentrations and medium pH were found to transiently increase with the addition of Zr-ACP, and are hypothesized to be responsible for the osteogenic effect of Zr-ACP.

PMID: 16278876 [PubMed - indexed for MEDLINE]

In vitro and in vivo release of ciprofloxacin from osteoconductive bone defect filler.

J Antimicrob Chemother. 2005 Dec;56(6):1063-8

Authors: M&#xE4;kinen TJ, Veiranto M, Lankinen P, Moritz N, Jalava J, Törmälä P, Aro HT

OBJECTIVES: Impregnation of antimicrobial agents within biodegradable carriers with osteoconductive properties could provide the means for one-stage surgical treatment of osteomyelitis. In this study, the in vitro and in vivo antibiotic release from this type of bone defect filler was characterized. METHODS: Cylindrical pellets (2.5 x 1.5 mm) were manufactured from bioabsorbable poly(L-lactide-co-glycolide) (PLGA) matrix, ciprofloxacin [8.3 +/- 0.1% (w/w)] and osteoconductive bioactive glass microspheres (90-125 microm) [27 +/- 2% (w/w)]. In vitro studies were carried out to delineate the release profile of the antibiotic. The antimicrobial activity of the release antibiotic was verified with MIC testing. In a time-sequence study in the rabbit, pellets were surgically implanted in the proximal tibia and the antibiotic concentrations achieved in bone were measured at 1, 2, 3, 4, 5 and 6 months. RESULTS: In vitro elution studies showed sustained release of ciprofloxacin at a therapeutic level (>2 microg/mL) over a time period of 4 months. The released ciprofloxacin had maintained its antimicrobial capacity against five standard ATCC strains. In vivo, the delivery system produced high local bone concentrations (247.9 +/- 91.0 mug/g of bone) for a time period of 3 months with no significant systemic exposure. Histomorphometry and micro-CT imaging confirmed new bone formation around the pellets within 3 months as a sign of an independent osteoconductive property of the composite. CONCLUSIONS: The tested composite seems to be a promising option for local therapy of surgically treated bone infections. The main advantages are the antibiotic release for a definite time period with therapeutic concentrations, which may minimize slow residual release at suboptimal concentrations.

PMID: 16234335 [PubMed - indexed for MEDLINE]

Formation characterization of hydroxyapatite on titanium by microarc oxidation and hydrothermal treatment.

J Biosci Bioeng. 2005 Jul;100(1):100-4

Authors: Liu F, Song Y, Wang F, Shimizu T, Igarashi K, Zhao L

Microarc oxidation (MAO) was performed on titanium in an electrolyte containing calcium glycerphosphate (Ca-GP) and calcium acetate (CA) using a direct current power supply. It was found that the MAO method is suitable forming a ceramic coating containing Ca and P using titanium, and that films display a porous and rough structure on their surface. Samples with a Ca/P ratio of 1.71 were hydrothermally treated in water solution whose pH was adjusted to 7.0-11.0 by adding NaOH at 190 degrees C for 10 h in an autoclave. Hydroxyapatite crystals were precipitated on the film surface after the hydrothermal treatment, and the amount of hydroxyapatite precipitated increased with increasing pH of water solution. The oxide film composition was semiquantitatively analyzed with an electron probe microanalyzer. The microstructures on the sample surfaces were observed by scanning electron microscopy before and after the hydrothermal treatment. The topography of the oxide film was imaged with an atomic force microscope. Its cross section was observed by scanning electron microscopy after being coated with a thin Au film. The surface structures of the films were analyzed by X-ray diffraction.

PMID: 16233858 [PubMed - indexed for MEDLINE]

Aptamer-based capture molecules as a novel coating strategy to promote cell adhesion.

J Cell Mol Med. 2005 Jul-Sep;9(3):731-6

Authors: Guo K, Wendel HP, Scheideler L, Ziemer G, Scheule AM

The improvement of the cytocompatibility of medical implants is a major goal in biomaterials research. During the last years many researchers worked on the fascinating approach to seed the respective cell types on various artificial substrates before implantation. For instance, cell-seeded implants are supposed to be better candidates for transplantable bone substitutes than conventional artificial bone grafts. To improve cell seeding efficiency and cytocompatibility, we designed a new coating material for medical implants. We used aptamers, highly specific cell binding nucleic acids generated by combinatorial chemistry with an in vitro selection called systematic evolution of exponential enrichment (SELEX). Aptamers do have high binding affinity and selectivity to their target. In our study, human osteoblasts from osteosarcoma tissue were used as a target to create the aptamer. Single aptamer mediated cell sorting assays showed the binding affinity with osteoblasts. Additionally, the aptamers immobilized on tissue culture plates could capture osteoblasts directly and rapidly from the cell solution. This model proves that aptamer coated artificial surfaces can greatly enhance cell adhesion. We assume that this strategy is capable to improve the clinical application of tissue engineered implants.

PMID: 16202220 [PubMed - indexed for MEDLINE]

Impaction bone grafting with hydroxyapatite: increased femoral component stability in experiments using Sawbones.

Acta Orthop. 2005 Aug;76(4):550-4

Authors: Fujishiro T, Nishikawa T, Niikura T, Takikawa S, Nishiyama T, Mizuno K, Yoshiya S, Kurosaka M

BACKGROUND: Substantial bone loss and bone defects increase the amount of allografting required in hip revision surgery. Thus, the use of a synthetic material to limit the amount of allograft tissue required for impaction grafting is desirable. We evaluated the potential of hydroxyapatite (HA) mixtures to provide initial mechanical stability to a polished tapered femoral stem. MATERIAL AND METHODS: We determined the initial stability of a polished tapered femoral stem after reconstructing a cavitary femoral bone defect by impaction bone grafting with cement in Sawbones composite femurs. Three types of graft material were tested for their ability to improve initial rotational stability. The graft materials investigated were pure allograft, a mixture of 50% allograft and 50% hydroxyapatite (HA), and pure HA. RESULTS: We found a statistically significant difference between the three groups as regards torsional micromotion and failure load. INTERPRETATION: Our findings suggest that reconstruction of femoral bone defects with pure HA or a mixture of allograft and HA provides adequate initial stability for femoral revision arthroplasty using impaction grafting.

PMID: 16195073 [PubMed - indexed for MEDLINE]

Poor results after augmenting autograft with xenograft (Surgibone) in hip revision surgery: a report of 27 cases.

Acta Orthop. 2005 Aug;76(4):544-9

Authors: Charalambides C, Beer M, Cobb AG

BACKGROUND: Surgibone Unilab is prepared from bovine bone and contains hydroxyapatite and protein. It is supposed to be immunogenically inert but the protein could be antigenic in man. PATIENTS AND METHODS: We followed 27 patients for an average of 2.5 (1-5) years, all of whom had received Surgibone mixed with autograft to fill in defects in the acetabulum and the proximal femur in revision hip surgery. RESULTS: In 17 patients, there was apparently complete incorporation of the bone graft within 6 months. In 3 of these patients, the graft was incorporated after 3 months. In 3 patients, however, there was no incorporation of the graft as late as 3 years after the operation. 3 other patients appeared to have a type of graft rejection (pseudoinfection). 1 other patient suffered MRSA deep infection of the prosthesis which resulted in removal of the implants 1 month postoperatively. INTERPRETATION: Use of Surgibone xenograft in revision hip surgery, even in combination with autograft, resulted in failure and the need for rerevision in at least one quarter of the cases studied.

PMID: 16195072 [PubMed - indexed for MEDLINE]

Bioactive glass efficacy in the periodontal healing of intrabony defects in monkeys.

Braz Dent J. 2005;16(1):67-74

Authors: Villa&#xE7;a JH, Novaes AB, Souza SL, Taba M, Molina GO, Carvalho TL

The purpose of this study was the histomorphologic analysis of the efficacy of bioactive glass particles with a narrow size range (Biogran) in the periodontal healing of 2-wall intrabony defects in monkeys. The 2-wall defects were made in the mesial area of the left and right second premolars of four monkeys, filled with gutta-percha and, after 15 days, they were debrided and either naturally filled with coagulum (control) or implanted with bioactive glass (test). In the control sites, the junctional epithelium migrated up to the base of the defect. The presence of newly formed cementum was more significant in the test defects. Both control and test sites showed newly formed bone at the base of the defect. The test defects presented foci of newly formed bone around and within the glass particles localized in the middle third, distant from the defect walls. Histologic analysis showed that the 300- to 355-microm bioactive glass particles aided new periodontal insertion. In conclusion, the tested bioactive glass had better healing potential than debridement only. The graft material showed a promising inhibition of apical migration of the junctional epithelium and greater cementum deposition on the radicular surface of the intrabony defects. The replacement of bioactive glass particles by new bone occurred due not only to an osteoconductive property, but also to an osteostimulatory capacity. Future investigations should evaluate this potential comparatively or together with other grafting materials, regenerative techniques and biological modifiers, as well as assess the longitudinal stability of the new attachment.

PMID: 16113937 [PubMed - indexed for MEDLINE]

Colloidal beta-tricalcium phosphate prepared by discharge in a modified body fluid facilitates synthesis of collagen composites.

J Dent Res. 2005 Sep;84(9):827-31

Authors: Shibata Y, Yamamoto H, Miyazaki T

The development of hydroxyapatite/collagen composites that are naturally synthesized and need no additional treatment is required for use in bone repair. Since reducing the diameter can increase the specific surface area of calcium phosphate particles that can conjugate collagen molecules, we expected colloidal calcium phosphates of submicron diameter obtained by discharge to be effective in formulating these composites. Additionally, since biodegradable beta-tricalcium phosphate has better osteoconductivity than hydroxyapatite, this study aimed to investigate the synthesis of colloidal hydroxyapatite and beta-tricalcium phosphate/collagen composites. Collagen molecules were tightly polymerized in the beta-tricalcium phosphate/collagen composite by catalysis of the generated -P-O-P- polyphosphate chain. Bonding strength between collagen NH+ amino groups and -P-O-P-, and cross-linking of the Ca++-RCOO- in the collagen were increased compared with those in the hydroxyapatite/collagen composite. These chemical reactions due to colloidal beta-tricalcium phosphate might play a key role in the synthesis of collagen composites.

PMID: 16109992 [PubMed - indexed for MEDLINE]

Management of periodontitis associated with endodontically involved teeth: a case series.

J Contemp Dent Pract. 2005 May 15;6(2):118-29

Authors: Anand PS, Nandakumar K

The pulp and the periodontal attachment are the two components that enable a tooth to function in the oral cavity. Lesions of the periodontal ligament and adjacent alveolar bone may originate from infections of the periodontium or tissues of the dental pulp. The simultaneous existence of pulpal problems and inflammatory periodontal disease can complicate diagnosis and treatment planning. The function of the tooth is severely compromised when either one of these is involved in the disease process. Treatment of disease conditions involving both of these structures can be challenging and frequently requires combining both endodontic and periodontal treatment procedures. This article presents cases of periodontitis associated with endodontic lesions managed by both endodontic and periodontal therapy.

PMID: 15915211 [PubMed - indexed for MEDLINE]

STEM and EDXS characterisation of physico-chemical reactions at the periphery of sol-gel derived Zn-substituted hydroxyapatites during interactions with biological fluids.

Colloids Surf B Biointerfaces. 2005 May 25;42(3-4):205-10

Authors: Jallot E, Nedelec JM, Grimault AS, Chassot E, Grandjean-Laquerriere A, Laquerriere P, Laurent-Maquin D

With its good properties of biocompatibility and bioactivity hydroxyapatite (HA) is highly used as bone substitutes and as coatings on metallic prostheses. In order to improve the bioactive properties of HA, we have elaborated Zn2+ doped hydroxyapatite. Zn2+ ions substitute for Ca2+ cations in the HA structure and four Zn concentrations (Zn/Zn+Ca) were prepared at 0.5, 1, 2 and 5 at.%. To study physico-chemical reactions at the materials periphery, we immersed the bioceramics into biological fluids for intervals from 1 day to 20 days. The surface changes were studied at the nanometer scale by scanning transmission electron microscopy associated with energy dispersive X-ray spectroscopy. After 20 days of immersion, we observed the formation of a calcium-phosphate layer at the periphery of the HA doped with 5% zinc. This layer contains magnesium and its thickness was around 200 nm. Formation of this Ca-P-Mg layer represents the bioactive properties of 5% Zn-substituted hydroxyapatite. This biologically active layer improves the properties of HA and will permit a chemical bond between the ceramic and bone.

PMID: 15893220 [PubMed - indexed for MEDLINE]

Bone formation in beta-tricalcium phosphate-filled bone defects of the rat femur: morphometric analysis and expression of bone related protein mRNA.

Biomed Res. 2005 Apr;26(2):51-9

Authors: Shiratori K, Matsuzaka K, Koike Y, Murakami S, Shimono M, Inoue T

The purpose of the current study was to evaluate the bone formation when beta-tricalcium phosphate (TCP) was implanted in bone defects of rat femurs. beta-TCP granules were applied to defects created in the femurs of 65 male rats who were sacrificed 3, 7, 10, 14 or 30 days later. Bone tissues were embedded in paraffin, serial sections were cut and then stained with hematoxylin-eosin. Histomorphometric analyses were also conducted. Furthermore, total mRNAs were extracted, homogenized, and reverse transcribed, after which quantitative PCR assays were conducted with a LightCycler using the double-stranded DNA dye Syber Green I with primers for either rat osteopontin or osteocalcin. Tissues in defects without beta-TCP were used as controls. The amount of newly formed bone tissue in the beta-TCP implanted group was significantly greater in both the side areas and the central area of defects than in the control group. Expressions of osteopontin and osteocalcin mRNAs of cells in the defects of the experimental group were up-regulated compared with the control group at all time periods. Taken together, these results prove that beta-TCP is an appropriate material for osteoconduction and promotes bone formation in bone defects.

PMID: 15889618 [PubMed - indexed for MEDLINE]

Dental devices; reclassification of tricalcium phosphate granules and classification of other bone grafting material for dental bone repair. Final rule.

Fed Regist. 2005 Apr 28;70(81):21947-50

Authors:

The Food and Drug Administration (FDA) is reclassifying tricalcium phosphate (TCP) granules for dental bone repair from class III to class II (special controls), classifying into class II (special controls) other bone grafting material for dental indications, and revising the classification name and identification of the device type. Bone grafting materials that contain a drug that is a therapeutic biologic will remain in class III and continue to require a premarket approval application. The classification identification includes materials such as hydroxyapatite, tricalcium phosphate, polylactic and polyglycolic acids, or collagen. This action is being taken to establish sufficient regulatory controls that will provide reasonable assurance of the safety and effectiveness of these devices. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document that will serve as the special control for the class II devices.

PMID: 15858911 [PubMed - indexed for MEDLINE]

Implant rehabilitation of the atrophic upper jaw: a review of the literature since 1999.

Med Oral Patol Oral Cir Bucal. 2005;10 Suppl 1:E45-56

Authors: Sorn&#xED; M, Guarinós J, García O, Peñarrocha M

The severely resorbed maxilla presents serious limitations for conventional implant placement. As a result, different techniques have been developed in the last two decades, with variable results. The most significant approaches comprise the placement of implants in anatomical abutments, elevation of the sinus floor, and reconstructive surgery with bone grafting. The present study reviews the most important articles on the management of the atrophic upper jaw published in the literature since 1999.

PMID: 15800467 [PubMed - indexed for MEDLINE]