Guided Bone Regeneration (guided + bone_regeneration)

Distribution by Scientific Domains

Selected Abstracts

In vitro change in mechanical strength of ,-tricalcium phosphate/copolymerized poly- L -lactide composites and their application for guided bone regeneration

Masanori Kikuchi
Abstract Novel composites of bioactive ,-tricalcium phosphate [Ca3(PO4)2] and biodegradable copolymerized poly- L -lactide (CPLA) were prepared by a heat-kneading method. The mechanical and chemical changes of the composites were evaluated in vitro by soaking in physiological saline and Dulbecco's phosphate buffered saline. When soaked in physiological saline, the 3-point mechanical strength decreased rapidly from 60 to 30 MPa in the initial 4 weeks and then gradually reached a plateau; the initial decrease in the mechanical strength was ascribed to the dissolution of ,-tricalcium phosphate from the surface. The mechanical properties evident at 8,12 weeks were sufficient for the composites to be used as a biodegradable material for regeneration of bone because the hydrolysis of CPLA was inhibited in both physiological saline and phosphate-buffered saline as a result of a pH-buffering effect. Composite membranes 250-,m thick were used to regenerate large bone defects in beagle dogs: 10 × 10 × 10 mm3 in volume in the mandible and 20 mm in length in the tibia. The afflicted areas covered with the composite membranes were almost perfectly filled with new bone 12 weeks after the operation, whereas those covered with a CPLA membrane or without any membranes were invaded by soft tissue. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 265,272, 2002 [source]

A composite polymer/tricalcium phosphate membrane for guided bone regeneration in maxillofacial surgery

Anita A. Ignatius
Abstract The aim of the study was the development of a resorbable membrane for guided bone regeneration (GBR) with improved biocompatibility, which should be stiff enough to avoid membrane collapse during bone healing. Combining a bioactive ceramic with a resorbable polymer may improve the biocompatibility and osteoconductivity of resorbable devices. The present article describes the preparation, the mechanical properties, and the in vitro degradation characteristic of a composite membrane made of poly(L, DL-lactide) and ,-tricalcium phosphate in comparison to a membrane made of pure poly(L, DL-lactide). The tensile strength and the elastic modulus as well as the molecular weight of the membranes were measured after in vitro degradation in buffer at 37 °C up to 28 weeks. The initial tensile strength of the composite and the polymer membrane was 37.3 ± 2.4 MPa and 27.7 ± 2.3 MPa and the elastic modulus 3106 ± 108 MPa and 3101 ± 104 MPa, respectively. The mechanical properties remained constant up to 8 weeks and then decreased slowly until week 28. The molecular weight of both membranes decreased steadily from 170,000 D to 30,000 D. It was concluded that the mechanical requirements for a membrane for GBR were fulfilled by the composite membrane. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 564,569, 2001 [source]

Healing patterns in calvarial bone defects following guided bone regeneration in rats

A micro-CT scan analysis
Abstract Objective: The objective of this study was to evaluate healing patterns of critical-size calvarial bone defects treated according to principles of guided bone regeneration using micro-CT scan analysis. Specifically, the contribution of bone, periosteum and dura mater to the amount and mineralization of newly formed bone was evaluated. Material and Methods: Surgically induced, critical-size calvarial bone defects in 48 adult male Wistar rats received the following: an occlusive expanded polytetrafluoroethylene (ePTFE) membrane at the exo- and endocranial aspect (OO; n = 12); an occlusive membrane at the exocranial and a perforated membrane at the endocranial aspect (OP; n = 12); a perforated membrane at the exocranial and an occlusive membrane at the endocranial aspect (PO; n = 12); and a perforated membrane at the exo- and endocranial aspect (PP; n = 12). The animals were euthanized at 4 weeks for quantitative analysis of bone volume fraction and mineralization in the region of interest (ROI) as well as in the external, middle and central area of the defect using micro-CT. Results: Bone volume fraction ranged from 31.4% (OP) to 24.5% (PP). No differences were found among the groups. Bone volume fraction and mineralization in the middle area were significantly greater in group OP than in group PP, and in the central area in group OO and PO than in group PP. Conclusions: The results of this study suggest that use of occlusive ePTFE membranes enhances bone formation and maturation in the calvarial skeleton. When occlusion of endo- and exocranial tissues was compromised by membrane perforation, impaired bone formation and mineralization were observed. [source]

Immediate Implant Placement: Clinical Decisions, Advantages, and Disadvantages

Monish Bhola DDS
Abstract Implant placement in fresh extraction sockets in conjunction with appropriate guided bone regeneration is well documented. The decision to extract teeth and replace them with immediate implants is determined by many factors, which ultimately affect the total treatment plan. The goal of this article is to review some of the important clinical considerations when selecting patients for immediate implant placement, and to discuss the advantages and disadvantages of this mode of therapy. [source]

Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine-derived xenograft: a randomized, controlled clinical trial

Nikos Mardas
Abstract Objectives: The aim of this randomized, controlled clinical trial was to compare the potential of a synthetic bone substitute or a bovine-derived xenograft combined with a collagen membrane to preserve the alveolar ridge dimensions following tooth extraction. Methods: Twenty-seven patients were randomized into two treatment groups following single tooth extraction in the incisor, canine and premolar area. In the test group, the alveolar socket was grafted with Straumann Bone Ceramic® (SBC), while in the control group, Bio-Oss® deproteinized bovine bone mineral (DBBM) was applied. In both groups, a collagen barrier was used to cover the grafting material. Complete soft tissue coverage of the barriers was not achieved. After 8 months, during re-entry procedures and before implant placement, the horizontal and vertical dimensions of the residual ridge were re-evaluated and trephine biopsies were performed for histological analysis in all patients. Results: Twenty-six patients completed the study. The bucco-lingual dimension of the alveolar ridge decreased by 1.1±1 mm in the SBC group and by 2.1±1 in the DBBM group (P<0.05). Both materials preserved the mesio-distal bone height of the ridge. No differences in the width of buccal and palatal bone plate were observed between the two groups. The histological analysis showed new bone formation in the apical part of the biopsies, which, in some instances, was in direct contact with both SBC and DBBM particles. The coronal part of the biopsies was occupied by a dense fibrous connective tissue surrounding the SBC and DBBM particles. Conclusion: Both biomaterials partially preserved the width and the interproximal bone height of the alveolar ridge. To cite this article: Mardas N, Chadha V, Donos N. Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine-derived xenograft: a randomized, controlled clinical trial. Clin. Oral Impl. Res. 21, 2010; 688,698. [source]

Collagen barrier membranes decrease osteoclastogenesis in murine bone marrow cultures

Hermann Agis
Abstract Objective: Collagen barrier membranes (CBM) are used for guided bone regeneration to support the process of graft consolidation. It remains, unknown however, whether CBM can affect the consolidation of bone grafts by controlling the differentiation of progenitor cells into bone-resorbing osteoclasts and bone-forming osteoblasts. Material and Methods: To gain an insight into the underlying mechanisms, we performed in vitro bone marrow cultures on CBM (Bio-Gide®) under conditions that favor osteoclastogenesis and osteoblastogenesis, respectively. Measures of osteoclastogenesis were based on the number of tartrate-resistant acid-phosphatase-positive (TRAP+) multinucleated cells. Resorption assays revealed the activity of mature osteoclasts. Osteoblastogenesis was determined by alkaline-phosphatase activity. Viability was investigated utilizing the MTT assay. Results: Cultivation of murine bone marrow on CBM reduced the number of TRAP+ multinucleated cells compared with cultures on tissue culture plates. Inhibition of osteoclastogenesis was observed on the porous and the dense CBM surfaces. The majority of TRAP+ cells were mononucleated and the decreased osteoclastogenesis was not due to changes in cell viability. Furthermore, CBM are inert regarding the resorptive activity of mature osteoclasts. Moreover, osteoblastogenesis was not reduced when bone marrow cells were grown on the surface of CBM. Conclusions: These in vitro findings demonstrate that CBM can reduce the formation but not the activity of multinucleated osteoclasts. Our data further reveal that the formation of osteogenic cells from their progenitors is not reduced by the CBM. Overall, our results suggest that the beneficial effects of CBM during graft consolidation may involve their direct impact on osteoclastogenesis. To cite this article: Agis H, Magdalenko M, Stögerer K, Watzek G, Gruber R. Collagen barrier membranes decrease osteoclastogenesis in murine bone marrow cultures. Clin. Oral Impl. Res. 21, 2010; 656,661. doi: 10.1111/j.1600-0501.2009.01888.x [source]

Immunohistochemical characterization of guided bone regeneration at a dehiscence-type defect using different barrier membranes: an experimental study in dogs

Frank Schwarz
Abstract Objectives: The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes. Material and methods: Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen-coated bone grafting material (BOC) in combination with either a native, three cross-linked, a titanium-reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin , OC, transglutaminase II , angiogenesis) and histomorphometrical analysis [e.g., bone-to-implant contact (BIC), area of new bone fill (BF)]. Results: In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10,12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group. Conclusion: Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level. [source]

Bone regeneration of dental implant dehiscence defects using a cultured periosteum membrane

Daiki Mizuno
Abstract Objectives: This study aimed to demonstrate the feasibility of a cultured periosteum (CP) membrane for use in guided bone regeneration at sites of implant dehiscence. Material and methods: Four healthy beagle dogs were used in this study. Implant dehiscence defects (4 × 4 × 3 mm) were surgically created at mandibular premolar sites where premolars had been extracted 3 months back. Dental implants (3.75 mm in diameter and 7 mm in length) with machined surfaces were placed into the defect sites (14 implants in total). Each dehiscence defective implant was randomly assigned to one of the following two groups: (1) PRP gel without cells (control) or (2) a periosteum membrane cultured on PRP gel (experimental). Dogs were killed 12 weeks after operation and nondecalcified histological sections were made for histomorphometric analyses including percent linear bone fill (LF) and bone-to-implant contact (BIC). Results: Bone regeneration in the treatment group with a CP membrane was significantly greater than that in the control group and was confirmed by LF analysis. LF values in the experimental and the control groups were 72.36±3.14% and 37.03±4.63%, respectively (P<0.05). The BIC values in both groups were not significantly different from each other. The BIC values in the experimental and the control groups were 40.76±10.30% and 30.58±9.69%, respectively (P=0.25) and were similar to native bone. Conclusion: This study demonstrated the feasibility of a CP membrane to regenerate bone at implant dehiscence defect. [source]

Effect of GBR in combination with deproteinized bovine bone mineral and/or enamel matrix proteins on the healing of critical-size defects

Nikolaos Donos
Abstract Objectives: To evaluate the effect of guided bone regeneration (GBR) in combination with or without deproteinized bovine bone mineral (DBBM) and/or an enamel matrix derivative (EMD) on the healing of critical-size calvarial defects. Material and methods: Forty rats were used. In all animals, a standardized critical-size calvarial defect was created surgically. The animals were randomly allocated into 4 groups of 10 animals each. Group A: One calvarial defect was left untreated, while the galeal and the cerebral aspect of the contralateral defect were covered with a bioresorbable membrane (GBR). Group B: One calvarial defect was filled with EMD, while the contralateral defect was treated with GBR and EMD. Group C: One defect was filled with DBBM, while the contralateral defect was treated with combination of GBR and DBBM. Group D: One defect was filled with DBBM combined with EMD, while the contralateral defect was treated with combination of GBR, DBBM and EMD. The healing period was 4 months. Five specimens from each group were macerated and the length, the width and the vertical dimension (thickness) of the remaining defect were evaluated by a stereomicroscope. The remaining specimens in each group were analyzed histologically. Results: The defects of the macerated specimens that were left untreated or were treated only by EMD, DBBM and combination of EMD and DBBM did not present predictably complete healing of the defects. All the defects where GBR was applied alone or combined with DBBM and/or EMD presented always complete healing (P<0.05). The combined use of GBR with EMD and/or DBBM did not offer any significant advantage above GBR alone in terms of healing of the length and the width of the defect. However, the vertical dimension of the defect was significantly higher (P<0.05) in the GBR-treated specimens of Groups C and D. The histological analysis supported these findings. Conclusion: The predictability of bone formation in critical-size defects depends mainly on the presence or absence of barrier membranes (GBR). The combined use with deproteinized bovine bone mineral and/or enamel matrix proteins did not significantly enhance the potential for complete healing provided by the GBR procedure. Résumé Le but de cette étude a été d'évaluer l'effet de l'association de la ROG avec ou sans minéral osseux bovin déprotéiné (DBBM) et/ou un dérivé de la matrice amélaire (EMD) sur la guérison de lésions crâniennes. Cette étude a eu recours à quarante rats. Chez tous les animaux, une lésion crânienne standardisée de grandeur critique a été créée chirurgicalement. Les animaux ont été répartis au hasard en quatre groupes de dix. Groupe A : une lésion crânienne fût laissée sans traitement, tandis que les deux côtés de la lésion latérale étaient recouvertes par une membrane biorésorbable (ROG), groupe B : une lésion crânienne remplie avec EMD tandis que la lésion contralatérale était traitée avec GBR et EMD, groupe C : une lésion remplie avec DBBM et la lésion contralatérale traitée par GBR et DBBM, Groupe D : une lésion remplie avec DBBM combinée avec EMD tandis que la lésion contralatérale a été traitée par une combinaison de ROG, DBBM et EMD. La période de guérison était de quatre mois. Cinq spécimens de chaque groupe ont été macérés et la longueur, la largeur et l'épaisseur de la lésion restante ont étéévaluées au stéréomicroscope. Les autres spécimens de chaque groupe ont été analysés histologiquement. Les lésions des spécimens macérés laissées sans traitement ou qui avaient été traitées seulement par EMD, DBBM et une combinaison de EMD et DBBM ne produisaient pas de manière prévisible une guérison complète des lésions. Toutes les lésions où la ROG était appliquée seule ou en association avec DBBM et /ou EMD présentaient toujours une guérison complète (p<0,05). L'utilisation conjointe de la ROG avec EMD et/ou DBBM n'offrait aucun avantage significatif sur la ROG seule en termes de guérison de la longueur et de la largeur de la lésion. Cependant la dimension verticale était significativement plus importante (p<0,05) dans les spécimens traités ROG des groupes C et D. L'analyse histologique a étayé ces découvertes. La prévision d'une formation osseuse dans les lésions de taille critique dépend essentiellement de la présence ou de l'absence de membranes barrières (ROG). L'utilisation combinée du minéral osseux bovin déprotéiné et /ou des protéínes de la matrice amélaire n'augmentait pas de manière significative le potentiel d'une guérison complète apportée par le processus ROG. Zusammenfassung Ziele: Die Untersuchung des Effekts der GBR in Kombination mit oder ohne deproteiniertem bovinem Knochenmineral (DBBM) und/oder einem Schmelzmatrix Derivat (EMD) auf die Heilung von Defekten mit kritischer Grösse. Material & Methoden: Es wurden 40 Ratten verwendet. Bei allen Tieren wurde auf der Calvaria chirurgisch ein standardisierter Defekt mit einer kritischen Grösse kreiert. Die Ratten wurden zufällig in 4 Gruppen mit je 10 Tieren aufgeteilt. Gruppe A: Ein Calvariadefekt wurde unbehandelt belassen, während der kontralaterale Defekt sowohl auf der cerebralen als auch auf der galealen Seite mit einer bioresorbierbaren Membran abgedeckt wurde (GBR). Gruppe B: Ein Calvariadefekt wurde mit EMD gefüllt, während der kontralaterale Defekt mit GBR und EMD behandelt wurde. Gruppe C: Ein Defekt wurde mit DBBM gefüllt, während der kontralaterale Defekt mit einer Kombination von GBR und DBBM behandelt wurde. Gruppe D: Ein Defekt wurde mit einer Kombination aus DBBM und EMD gefüllt, während der kontralaterale Defekt mit einer Kombination von GBR, DBBM und EMD behandelt wurde. Die Heilungszeit betrug 4 Monate. Fünf Präparate von jeder Gruppe wurden mazeriert und es wurden die Länge, die Breite und vertikale Dimension (Dicke) des verbleibenden Defekts unter dem Stereomikroskop ausgewertet. Die übrigen Präparate jeder Gruppe wurden histologisch analysiert. Resultate: Die Defekte der mazerierten Präparate, welche unbehandelt belassen oder nur mit EMD,DBBM und einer Kombination von EMD und DBBM behandelt worden waren, zeigten keine voraussagbare komplette Heilung der Defekte. Alle Defekte, bei denen GBR allein oder in Kombination mit DBBM und/oder EMD appliziert worden war, zeigten immer eine komplette Heilung (P>0.05). Die Kombination von GBR mit EMD und/oder DBBM bot gegenüber der GBR allein keine signifikanten Vorteile bezüglich Ausheilung der Länge und Breite der Defekte. Jedoch war die vertikale Dimension der Defekte bei den GBR behandelten Präparaten der Gruppen C und D signifikant grösser (P>0.05). Die histologische Analyse unterstützte diese Befunde. Schlussfolgerung: Die Voraussagbarkeit der Knochenbildung in Defekten mit kritischer Grösse hängt hauptsächlich von der Präsenz oder Absenz von Barrieremembranen (GBR) ab. Die kombinierte Verwendung von deproteiniertem bovinem Knochenmineral und/oder Schmelzmatrix Proteinen verbesserte das Potential für eine komplette Defektausheilung durch das GBR Verfahren nicht signifikant. Resumen Objetivos: Evaluar el efecto de GBR en combinación con o sin mineral óseo bovino desproteinizado (DBBM) y/o derivado de la matriz del esmalte (EMD) en la cicatrización de defectos de tamaño crítico en el calvario. Material y Métodos: Se usaron cuarenta ratas. En todos los animales se creó quirúrgicamente un defecto estándar de tamaño crítico en el calvario. Los animales se alojaron aleatoriamente en 4 grupos de 10 animales. Grupo A: Un defecto del calvario se dejó sin tratar, mientras que los aspectos galeales y cerebrales del defecto contralateral se cubrieron con una membrana biorreabsorbible (GBR). Grupo B: Un defecto del calvario se rellenó con EMD, mientras que el defecto contralateral se trató con GBR y EMD. Grupo C: Un defecto se rellenó con DBBM, mientras el defecto contralateral se trató con una combinación de GBR y DBBM. Grupo D: UN defecto se rellenó con DBBM combinado con EMD, mientras que el defecto contralateral se trató con una combinación de GBR, DBBM y EMD. El periodo de cicatrización fue de 4 meses. Cinco especímenes de cada grupo se maceraron, y se evaluó la longitud, la anchura y la dimensión vertical (grosor) del defecto remanente por estereomicroscopía. Los especímenes restantes de cada grupo se analizaron histológicamente. Resultados: Los defectos de los especímenes macerados que se dejaron sin tratar o se trataron solo con EMD, DBBM y una combinación de EMD y DBBM no presentaron una cicatrización completa predecible de los defectos. Todos los defectos en los que se aplicó GBR sola o combinada con DBBM y/o EMD siempre presentó cicatrización completa (p<0.05). El uso combinado de GBR con EMD y/o DBBM no ofreció ninguna ventaja significativa sobre GBR solo en términos de cicatrización de la longitud y la anchura del defecto. De todos modos, la dimensión vertical del defecto fue significativamente mayor (p<0.05) in los grupos tratados con GBR de los grupos C y D. Los análisis histológicos apoyaron estos hallazgos. Conclusión: La predictibilidad de la formación de hueso en defectos de tamaño crítico depende principalmente de la presencia o ausencia de membranas de barrera (GBR). El uso combinado con mineral óseo bovino desproteinizado y/o proteínas de la matriz del esmalte no realzaron significativamente el potencial para la cicatrización completa suministrado por el procedimiento de GBR. [source]