Deproteinized Bovine Bone Mineral or Autologous Bone at Dehiscence Type Defects at Implants Installed Immediately into Extraction Sockets: An Experimental Study in Dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

New LLLT protocol to speed up the bone healing process-histometric and immunohistochemical analysis in rat calvarial bone defect

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of oestrogen deficiency and 17 beta-estradiol therapy on bone healing in calvarial critical size defects treated with bovine bone graft

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The RANK/RANKL/OPG interaction in the repair of autogenous bone grafts in female rats with estrogen deficiency

The aim of this study was to evaluate the resorption process during the repair of autogenous bone grafts with or without coverage by an expanded polytetrafluoroethylene (e-PTFE) membrane in female rats with estrogen deficiency using the immunohistochemical technique. Eighty female rats were randomly divided into two groups (OVX and SHAM). The 40 female rats in the OVX group were subjected to ovariectomy, and the 40 female rats in the SHAM group were subjected to simulated ovariectomy. The two groups were further divided in subgroup E, which was subjected to surgery for placement of autogenous bone graft (ABG), and subgroup ME, in which the ABG was covered with an e-PTFE membrane. The animals were killed at 0, 7, 21,45 and 60 days. The specimens were analyzed using immunohistochemistry for the bone resorption markers RANK, RANK-L and Osteoprotegerin (OPG). A higher remodeling rate was observed at 7 and 21 days after the autogenous bone grafts, when the markers were more intensely expressed. At the final time point, the specimens presented similar characteristics to those observed at the initial time point. The expression of immunohistochemical markers was not altered by the estrogen deficiency. The presence of the e-PTFE membrane delayed the bone resorption process, influencing the immunohistochemical expression of markers.

Bone morphogenetic proteins: promising molecules for bone healing, bioengineering, and regenerative medicine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An alternative maneuver to treat gingival recession

This article reports a clinical case in which was applied autologous bone graft associated with subepithelial connective tis- sue graft, harvested by gingivectomy procedure with technical modifications to increase gingival graft extension, also to be used as guided tissue regeneration, to treat a single gingival recession. After 1 year and 2 months of follow-up, the cover- age of the recession was 4.0 mm, which corresponded to the gain of attached keratinized gingival tissue. An increase in the gingival tissue thickness was observed, without significant probing depth. The procedures applied to treat this case may be biologically and clinically useful to treat gingival recession.

Localized periodontal disease induced by bacterial plaque and palatal radicular groove: treatment and considerations

The palatal radicular groove is a morphological tooth defect, which act as local predisposing risk factor favoring accumulation of the bacterial plaque, permitting microbial invasion via root groove way, directly into periodontal structures. A patient diagnosed with palatal radicular groove and a localized periodontal disease was treated by procedures to control bacterial action and procedures to eliminate local predisposing risk factor. To treat the periodontal bone defect a sequelae of periodontal disease, a guided tissue regeneration technique was applied by using allograft and xenograft materials associated with a resorbable demineralized bovine cortical bone membrane. The objective of surgical regenerative procedure was to recover the periodontal tissues nearly as they were before periodontal disease destruction.

Estudo do processo de reparo de enxerto ósseo em bloco submetido ao recobrimento com etil-cianoacrilato: análise histométrica e imunoistoquímica em ratos

Pós-graduação em Odontologia - FOA

The Behavior of Demineralized Bone Matrix (DBM) in Post-Extraction Sockets

Autogenous bone grafts are considered to be the gold standard in bone regeneration because of their osteogenic activity; however, due to limited availability of intraoral donor sites and the need to resolve the demands of patients requires an alternative to these. Two male patients were submitted to implant surgery in two stages with 6 months intervals between each of them: the first was exodontia and placement of DBM graft into the socket; the second stage was the drill with a 2 mm internal diameter trephine in center of the alveolar ridge previously grafted with DBM and subsequent implant placement. The samples were analyzed under histological techniques. A very mature bone was observed at 6 months after DBM graft placement in the sockets, showing it to be a good alternative as bone graft.

DEVELOPMENT OF AN EXPERIMENTAL MODEL OF INFECTED BONE VOID IN THE ULNA OF RABBITS

Objective: Develop a model that allowed the study of bone regeneration in infection conditions. Method: A 15 mm defect was surgically created in the rabbit ulna and inoculated with 5x10(8) colony-forming units (CFU) of S. aureus. Surgical debridement was performed two weeks after and systemic gentamicin was administered for four weeks. Animals were followed up to 12 weeks to evaluate infection control and bone regeneration. Result: Bone regeneration was inferior to 25% of the defect in radiological and histological analysis. Conclusion: Infected bone defect of 15 mm in the rabbit ulna was unable to achieve full regeneration without further treatment. Level of Evidence V, Experimental Study.

Implant Osseointegration in Circumferential Bone Defects Treated with Latex-Derived Proteins or Autogenous Bone in Dog's Mandible

Background: In sites with diminished bone volume, the osseointegration of dental implants can be compromised. Innovative biomaterials have been developed to aid successful osseointegration outcomes. Purpose: The aim of this study was to evaluate the osteogenic potential of angiogenic latex proteins for improved bone formation and osseointegration of dental implants. Materials and Methods: Ten dogs were submitted to bilateral circumferential defects (5.0 x 6.3 mm) in the mandible. Dental implant (3.3 x 10.0 mm, TiUnite MK3 (TM), Nobel Biocare AB, Goteborg, Sweden) was installed in the center of the defects. The gap was filled either with coagulum (Cg), autogenous bone graft (BG), or latex angiogenic proteins pool (LPP). Five animals were sacrificed after 4 weeks and 12 weeks, respectively. Implant stability was evaluated using resonance frequency analysis (Osstell Mentor T, Osstell AB, Goteborg, Sweden), and bone formation was analyzed by histological and histometric analysis. Results: LPP showed bone regeneration similar to BG and Cg at 4 weeks and 12 weeks, respectively (p >= 3.05). Bone formation, osseointegration, and implant stability improved significantly from 4 to 12 weeks (p <= 2.05). Conclusion: Based on methodological limitations of this study, Cg alone delivers higher bone formation in the defect as compared with BG at 12 weeks; compared with Cg and BG, the treatment with LPP exhibits no advantage in terms of osteogenic potential in this experimental model, although overall osseointegration was not affected by the treatments employed in this study.

Bacterial cellulose-collagen nanocomposite for bone tissue engineering

A nanocomposite based on bacterial cellulose (BC) and type I collagen (COL) was evaluated for in vitro bone regeneration. BC membranes were modified by glycine esterification followed by cross-linking of type I collagen employing 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. Collagen incorporation was studied by spectroscopy analysis. X-Ray diffraction showed changes in the BC crystallinity after collagen incorporation. The elastic modulus and tensile strength for BC-COL decreased, while the strain at failure showed a slight increase, even after sterilization, as compared to pristine BC. Swelling tests and contact angle measurements were also performed. Cell culture experiments performed with osteogenic cells were obtained by enzymatic digestion of newborn rat calvarium revealed similar features of cell morphology for cultures grown on both membranes. Cell viability/proliferation was not different between BC and BC-COL membranes at day 10 and 14. The high total protein content and ALP activity at day 17 in cells cultured on BC-COL indicate that this composite allowed the development of the osteoblastic phenotype in vitro. Thus, BC-COL should be considered as alternative biomaterial for bone tissue engineering.

Chitosan-based biomaterials used in critical-size bone defects: radiographic study in rat's calvaria

OBJETIVO: Este estudo avaliou através de imagens radiográficas digitais, a ação de biomateriais de quitosana e de cloridrato de quitosana, com baixo e alto peso molecular, utilizados na correção de defeitos ósseos de tamanho crítico (DOTC)em calvária de ratos. MATERIAL E MÉTODO: DOTCs com 8 mm de diâmetro foram criados cirurgicamente na calvária de 50 ratos Holtzman. Em 10 animais o defeito foi preenchido foram preenchidos com coágulo sanguíneo (controle negativo). Os 40 animais restantes foram divididos de acordo com o biomaterial utilizado no preenchimento do defeito (quitosana de baixo peso e de alto peso molecular, e cloridrato de quitosana de baixo e de alto peso molecular), e foram avaliados em dois períodos experimentais (15 e 60 dias), totalizando 5 animais/biomaterial/período de avaliação. RESULTADO: A avaliação radiográfica foi feita utilizando duas radiografias digitais do crânio do animal: uma tomada logo após o defeito ósseo ser criado e a outra no momento do sacrifício. Nessas imagens, foi avaliada a densidade óssea radiográfica inicial e a final na área do defeito, que foram comparadas. As análises na densidade óssea radiográfica indicaram aumento da densidade óssea radiográfica dos DOTCs tratados para todos os biomateriais testados, em ambos os períodos. Resultados semelhantes foram encontrados no grupo controle. CONCLUSÃO: Conclui-se que os biomateriais de quitosana testados não foram capazes de aumentar a densidade radiográfica em DOTC realizados em calvária de ratos.

Bioinspired fabrication of biosilica-based bone substitution materials

Until today, autogenic bone grafts from various donor regions represent the gold standard in the field of bone reconstruction, providing both osteoinductive and osteoconductive characteristics. However, due to low availability and a disequilibrium between supply and demand, the risk of disease transfer and morbidity, usually associated with autogeneic bone grafts, the development of biomimic materials with structural and chemical properties similar to those of natural bone have been extensively studied. So far,rnonly a few synthetic materials, so far, have met these criteria, displaying properties that allow an optimal bone reconstitution. Biosilica is formed enzymatically under physiological-relevant conditions (temperature and pH) via silicatein (silica protein), an enzyme that was isolated from siliceous sponges, cloned, and prepared in a recombinant way, retaining its catalytic activity. It is biocompatible, has some unique mechanical characteristics, and comprises significant osteoinductive activity.rnTo explore the application of biosilica in the fields of regenerative medicine,rnsilicatein was encapsulated, together with its substrate sodium metasilicate, into poly(D,L-lactide)/polyvinylpyrrolidone(PVP)-based microspheres, using w/o/wrnmethodology with solvent casting and termed Poly(D,L-lactide)-silicatein silicacontaining-microspheres [PLASSM]. Both silicatein encapsulation efficiency (40%) and catalytic activity retention upon polymer encapsulation were enhanced by addition of an essential pre-emulsifying step using PVP. Furthermore, the metabolic stability, cytoxicity as well as the kinetics of silicatein release from the PLASSM were studied under biomimetic conditions, using simulated body fluid. As a solid support for PLASSM, a polyvinylpyrrolidone/starch/Na2HPO4-based matrix (termed plastic-like filler matrix containing silicic acid [PMSA]) was developed and its chemical and physical properties determined. Moreover, due to the non-toxicity and bioinactivity of the PMSA, it is suggested that PMSA acts as osteoconductive material. Both components, PLASSM and PMSA, when added together, form arnbifunctional 2-component implant material, that is (i)non-toxic(biocompatible), (ii)moldable, (iii) self-hardening at a controlled and clinically suitable rate to allows a tight insertion into any bone defect (iv) biodegradable, (v)forms a porous material upon exposure to body biomimetic conditions, and (vi)displays both osteoinductive (silicatein)and osteoconductive (PMSA) properties.rnPreliminary in vivo experiments were carried out with rabbit femurs, by creatingrnartificial bone defects that were subsequently treated with the bifunctional 2-component implant material. After 9 weeks of implantation, both computed tomography (CT) and morphological analyses showed complete resorption of the implanted material, concurrent with complete bone regeneration. The given data can be considered as a significant contribution to the successful introduction of biosilica-based implants into the field of bone substitution surgery.

Tissue engineering strategies for biomaterial-based anticancer drug delivery and enhancement of angiogenesis in tumor-resected bone

Patienten, die an Osteosarkom leiden werden derzeit mit intravenös applizierten krebstherapeutischen Mitteln nach Tumorresektion behandelt, was oftmals mit schweren Nebenwirkungen und einem verzögerten Knochenheilungsprozess einhergeht. Darüber hinaus treten vermehrt Rezidive aufgrund von verbleibenden neoplastischen Zellen an der Tumorresektionsstelle auf. Erfolgreiche Knochenregeneration und die Kontrolle von den im Gewebe verbleibenden Krebszellen stellt eine Herausforderung für das Tissue Engineering nach Knochenverlust durch Tumorentfernung dar. In dieser Hinsicht scheint der Einsatz von Hydroxyapatit als Knochenersatzmaterial in Kombination mit Cyclodextrin als Medikamententräger, vielversprechend. Chemotherapeutika können an Biomaterial gebunden und direkt am Tumorbett über einen längeren Zeitraum freigesetzt werden, um verbliebene neoplastische Zellen zu eliminieren. Lokal applizierte Chemotherapie hat diverse Vorteile, einschließlich der direkten zytotoxischen Auswirkung auf lokale Zellen, sowie die Reduzierung schwerer Nebenwirkungen. Diese Studie wurde durchgeführt, um die Funktionsfähigkeit eines solchen Arzneimittelabgabesystems zu bewerten und um Strategien im Bereich des Tissue Engineerings zu entwickeln, die den Knochenheilungsprozess und im speziellen die Vaskularisierung fördern sollen. Die Ergebnisse zeigen, dass nicht nur Krebszellen von der chemotherapeutischen Behandlung betroffen sind. Primäre Endothelzellen wie zum Beispiel HUVEC zeigten eine hohe Sensibilität Cisplatin und Doxorubicin gegenüber. Beide Medikamente lösten in HUVEC ein tumor-unterdrückendes Signal durch die Hochregulation von p53 und p21 aus. Zudem scheint Hypoxie einen krebstherapeutischen Einfluss zu haben, da die Behandlung sensitiver HUVEC mit Hypoxie die Zellen vor Zytotoxizität schützte. Der chemo-protektive Effekt schien deutlich weniger auf Krebszelllinien zu wirken. Diese Resultate könnten eine mögliche chemotherapeutische Strategie darstellen, um den Effekt eines zielgerichteten Medikamenteneinsatzes auf Krebszellen zu verbessern unter gleichzeitiger Schonung gesunder Zellen. Eine erfolgreiche Integration eines Systems, das Arzneimittel abgibt, kombiniert mit einem Biomaterial zur Stabilisierung und Regeneration, könnte gesunden Endothelzellen die Möglichkeit bieten zu proliferieren und Blutgefäße zu bilden, während verbleibende Krebszellen eliminiert werden. Da der Prozess der Knochengeweberemodellierung mit einer starken Beeinträchtigung der Lebensqualität des Patienten einhergeht, ist die Beschleunigung des postoperativen Heilungsprozesses eines der Ziele des Tissue Engineerings. Die Bildung von Blutgefäßen ist unabdingbar für eine erfolgreiche Integration eines Knochentransplantats in das Gewebe. Daher ist ein umfangreich ausgebildetes Blutgefäßsystem für einen verbesserten Heilungsprozess während der klinischen Anwendung wünschenswert. Frühere Experimente zeigen, dass sich die Anwendung von Ko-Kulturen aus humanen primären Osteoblasten (pOB) und humanen outgrowth endothelial cells (OEC) im Hinblick auf die Bildung stabiler gefäßähnlicher Strukturen in vitro, die auch effizient in das mikrovaskuläre System in vivo integriert werden konnten, als erfolgreich erweisen. Dieser Ansatz könnte genutzt werden, um prä-vaskularisierte Konstrukte herzustellen, die den Knochenheilungsprozess nach der Implantation fördern. Zusätzlich repräsentiert das Ko-Kultursystem ein exzellentes in vitro Model, um Faktoren, welche stark in den Prozess der Knochenheilung und Angiogenese eingebunden sind, zu identifizieren und zu analysieren. Es ist bekannt, dass Makrophagen eine maßgebliche Rolle in der inflammatorisch-induzierten Angiogenese spielen. In diesem Zusammenhang hebt diese Studie den positiven Einfluss THP-1 abgeleiteter Makrophagen in Ko-Kultur mit pOB und OEC hervor. Die Ergebnisse zeigten, dass die Anwendung von Makrophagen als inflammatorischer Stimulus im bereits etablierten Ko-Kultursystem zu einer pro-angiogenen Aktivierung der OEC führte, was in einer signifikant erhöhten Bildung blutgefäßähnlicher Strukturen in vitro resultierte. Außerdem zeigte die Analyse von Faktoren, die in der durch Entzündung hervorgerufenen Angiogenese eine wichtige Rolle spielen, eine deutliche Hochregulation von VEGF, inflammatorischer Zytokine und Adhäsionsmoleküle, die letztlich zu einer verstärkten Vaskularisierung beitragen. Diese Resultate werden dem Einfluss von Makrophagen zugeschrieben und könnten zukünftig im Tissue Engineering eingesetzt werden, um den Heilungsprozess zu beschleunigen und damit die klinische Situation von Patienten zu verbessern. Darüber hinaus könnte die Kombination der auf Ko-Kulturen basierenden Ansätze für das Knochen Tissue Engineering mit einem biomaterial-basierenden Arzneimittelabgabesystem zum klinischen Einsatz kommen, der die Eliminierung verbliebener Krebszellen mit der Förderung der Knochenregeneration verbindet.