Rehabilitation of Atrophic Maxilla Using the Combination of Autogenous and Allogeneic Bone Grafts Followed by Protocol-Type Prosthesis

Currently, there are several techniques for the rehabilitation of atrophic maxillary ridges in literature. The grafting procedure using autogenous bone is considered ideal by many researchers, as it shows osteogenic capability and causes no antigenic reaction. However, this type of bone graft has some shortcomings, mainly the restricted availability of donor sites. In recent years, several alternatives have been investigated to supply the disadvantages of autogenous bone grafts. In such studies, allogeneic bone grafts, which are obtained from individuals with different genetic load, but from the same species, have been extensively used. They can be indicated in cases of arthroplasty, surgical knee reconstruction, large bone defects, and in oral and maxillofacial reconstruction. Besides showing great applicability and biocompatibility, this type of bone is available in unlimited quantities. on the other hand, allogeneic bone may have the disadvantage of transmitting infectious diseases. Atrophic maxillae can be treated with bone grafts followed by osseointegrated implants to obtain aesthetic and functional oral rehabilitation. This study aimed to show the viability of allogeneic bone grafting in an atrophic maxilla, followed by oral rehabilitation with dental implant and protocol-type prosthesis within a 3-year follow-up period by means of a clinical case report.

Enxerto ósseo esponjoso autólogo em pequenos animais

O enxerto ósseo esponjoso autólogo é formado por osso trabecular, poroso e altamente celular. Visto ser de fundamental importância na cirurgia ortopédica de pequenos animais, o trabalho teve por objetivo discorrer sobre a função, locais de colheita, cuidados, formas de aplicação, indicações e contra-indicações desse enxerto. Ele estimula a formação óssea devido ao fornecimento de células vivas e fatores de crescimento, mas não possui suporte mecânico. A asa do ílio craniodorsal, úmero proximal, tíbia proximal e fêmur distal, são os locais de colheita mais utilizados em cães. A asa do ílio consiste no local mais satisfatório para gatos. Para maximizar a incorporação do enxerto com o tecido hospedeiro, devem ser tomados alguns cuidados entre a colheita e a transferência para a área receptora. Além disso, pode ser aplicado sem compressão dentro do local recipiente. A freqüência de complicações é considerada baixa.

Clinical similarities and histological diversity comparing fresh frozen onlay bone blocks allografts and autografts in human maxillary reconstruction

Background: In the absence of autologous bone for harvesting, fresh-frozen bone allografts turned into an alternative for bone reconstruction procedures. Purpose: The purpose of this study was to make a histological analysis of fresh-frozen onlay bone allografts (ALs), compared with autografts, in patients who needed maxillary reconstruction prior to dental implants placement. Materials and Methods: Twelve patients with bone deficiencies (width inferior to 4mm) in the sites where the implants were planned were enrolled in the study. From these, six were elected to be treated with autogenous (AT) bone grafts and six with fresh-frozen bone AL. This last group included the patients who had absence of a convenient amount of bone in donor sites. Each patient received from one to six graft blocks, totalling to 12 ATs and 17 ALs. Seven months after grafting procedures, biopsies of the grafts were made using 2-mm internal diameter trephine burs, and processed for histological analysis. One biopsy was retrieved from each patient. Results: Clinically, all grafts were found to be firm in consistency and well-incorporated to the receptor bed. Histological analysis showed a large amount of necrotic bone surrounded by few spots of new-formed bone in the AL group, suggesting low rate of graft remodeling. In the AT group, an advanced stage of bone remodeling was seen. Conclusions: Human fresh-frozen bone block AL showed clinical compatibility for grafting procedures, although associated to slow remodeling process. Further studies are needed to define, at long term, the remodeling process chronology the clinical longitudinal results for fresh-frozen bone AL. Copyright © 2013 Wiley Periodicals, Inc.

Enxerto autógeno para aumento em espessura e ou altura do processo ósseo alveolar, transtornos de técnica cirúrgica, complicações e sobrevivência dos implantes

Pós-graduação em Odontologia - FOA

Alveolar ridge augmentation with the perforated and nonperforated bone grafts

Purpose: Autogenous bones are frequently used because of their lack of antigenicity, but good osteoconductive and osteoinductive properties. This study evaluated the biological behavior of perforated and nonperforated cortical block bone grafts.Methods: Ten nonsmoking patients who required treatment due to severe resorption of the alveolar process and subsequent implant installation were included in the study. The inclusion criteria was loss of one or more teeth; the presence of atrophy of the alveolar process with the indication of reconstruction procedures to allow rehabilitation with dental implants; and the absence of systemic disease, local infection, or inflammation. The patients were randomly divided into two groups based on whether they received a perforated (inner surface) or nonperforated graft. After a 6-month healing period, a biopsy was performed and osseointegrated implants were installed in the same procedure.Results: Fibrous connective tissue was evident at the interface in patients who received nonperforated grafts. However, full union between the graft and host bed was visible in those who had received a perforated graft.Conclusions: We found that cortical inner side perforations at donor sites increased the surface area and opened the medullary cavity. Our results indicate an increased rate of graft incorporation in patients who received such perforated grafts.

Reabilitação total da maxila com enxerto intraoral: relato de caso

The early tooth loss and periodontal disease often leave inadequate bone volume for installation of osseointegrated implants. The autogenous bone graft is considered the gold standard for reconstruction of residual bone defects. Some surgical techniques can be performed, including extra or intraoral donor sites depending on the degree of bone loss, depending on surgical-prosthetic planning and general condition of the patient. The intraoral bone grafts offer a safe option to rebuilt bone volume in smaller rehabilitations, with low morbidity and minimal postoperative discomfort. Among the possible donor sites, the mandibular ramus and body, which offer predominantly cortical bone, and the chin area, which offers corticomedullary bone tissue, can be harvested. The graft will be suitable both in quantity and quality, preserving the capacity of osteogenesis, osteoinduction and osteoconduction, which differentiate autogenous grafts from other biomaterials. The aim of this study was to report a clinical case in which the mandibular ramus graft was used for total reconstruction of an edentulous maxilla, showing that even large areas can be reconstructed with grafts from intraoral origin. All the steps that allowed the complete reconstruction of the maxilla done by an intraoral donor area are listed in the text, culminating in an extremely satisfactory clinical result.

Avaliação da espessura do osso parietal como região doadora de enxertos ósseos.

Introduction: The study of graft donor sites, whether from the anatomical, physiological or morphological point of view, has become a topic of current interest, due to the increasing number of patients needing facial bone reconstruction for various reasons. Purpose: In view of the need to constantly improve surgical techniques for autogenous bone graft harvesting, still considered the best choice for facial bone reconstruction, this paper describes an anatomical study on dry skulls in order to evaluate the average thickness of the parietal bone. Material and Methods: Measurements of this bone were taken with a goniometer, at four previously defined points, in the region that is often used as a donor site, in 49 dry skulls (98 parietal bones). The results were evaluated using the T test. Results: Thickness was measured at four predetermined points. The mean values (Point A = 4898mm, B = 4517mm, C = 6185mm, D = 4280mm) show that the bone can be even thinner than previously reported in the literature in other studies of the same nature. The largest bone thickness is in the medial and posterior region. Conclusion: A knowledge of these anatomical characteristics is helpful in preventing possible surgical complications, as well as making it safer for the surgeon to remove this graft and providing more information on whether or not to indicate this region as a bone graft donor site.

Surgical techniques for maxillary bone grafting: literature review

For oral rehabilitation with implant-supported prostheses, there are required procedures to create the bone volume needed for installation of the implants. Thus, bone grafts from intraoral or extraoral donor sites represent a very favorable opportunity. This study aimed to review the literature on the subject, seeking to discuss parameters for the indications, advantages and complications of techniques for autogenous bone grafts.

Immunohistochemical, tomographic, and histological study on onlay bone graft remodeling. Part III: allografts

Objective In the last decades aroused the interest for bone tissue bank as an alternative to autogenous grafting, avoiding donor sites morbidity, surgical time, and costs reduction. The purpose of the study was to compare allografts (ALg) with autografts (AUg) using histology, immunochemistry, and tomographic analysis. Material and methods Fifty-six New Zealand White rabbits were submitted to surgical procedures. Twenty animals were donors and 36 were actually submitted to onlay grafting with ALg (experimental group) and AUg (control group) randomly placed bilaterally in the mandible. Six animals of each group were sacrificed at 3, 5, 7, 10, 20, and 60 postoperative days. Immunolabeling was accomplished with osteoprotegerin (OPG); receptor activator of nuclear factor-k ligand (RANKL); alkaline phosphatase (ALP); osteopontin (OPN); vascular endothelial growth factor (VEGF); tartrate-resistant acid phosphatase (TRAP); collagen type I (COL I); and osteocalcin (OC). Density and volume of the grafts was evaluated on tomography obtained at the surgery and sacrifice. Results The ALg and AUg exhibited similar patterns of density and volume throughout the experiments. The intra-group data showed statistical differences at days 7 and 60 in comparison with other time points (P = 0.001), in both groups. A slight graft expansion from fixation until day 20 (P = 0.532) was observed in the AUg group and then resorbed significantly at the day 60 (P = 0.015). ALg volume remained stable until day 7 and decreased at day 10 (P = 0.045). The light microscopy analysis showed more efficient incorporation of AUg onto the recipient bed if compared with the ALg group. The immunohistochemical labeling picked: at days 10 and 20 with OPG in the AUg group and at day 7 with TRAP in the ALg group (P = 0.001 and P = 0.002, respectively). Conclusions ALg and AUg were not differing in patterns of volume and density during entire experiment. Histological data exhibit more efficient AUg incorporation into recipient bed compared with the ALg group. Immunohistochemistry outcomes demonstrated similar pattern for both ALg and AUg groups, except for an increasing resorption activity in the ALg group mediated by TRAP and in the AUg group by higher OPG labeling. However, this latter observation does not seem to influence clinical outcomes.

Reconstrução de maxila severamente atrófica via enxerto ósseo autógeno de calota craniana: descrição de técnica

Bone reconstructions are traditionally conducted with autogenous grafts harvested from intra- or extra-oral donor sites to reestablish the lost bone volume for further implant-prosthetic rehabilitation. The calvarial bone has been studied as an excellent donor site in large atrophic situations, presenting low resorption rates, as well as complications and minimal morbidity. The hospitalization time is short, with low pain levels, short functional limitations, and invisible scars. The skull microarchitecture is predominantly cortical in the presence of growth factors that demonstrate their osteogenic, osteoinductive, and osteoconductive abilities resulting in low resorption rate and high predictability when compared to the iliac crest. Dural lacerations, extra and subdural bleeding, cerebrospinal fluid leakage, and brain damage have been minimized due to the development of surgical technique. The delimitation of diploe, preserving the internal skull cortex before osteotomy at the donor made it possible to reduce accidents and complications. The aim of this paper is to show a technical and to discuss aspects of the use of calvarial bone in the reconstruction of severely atrophic maxilla for oral rehabilitation with osseointegrated implants.

Enxerto ósseo em odontologia: revisão de literatura

Bone is a specialized connective tissue, vascular and dynamic changes over the life of the organism. When injured, has a unique ability to regenerate and repair without the presence of scars, but in some situations due to the size of the defect, the bone tissue does not regenerate so completely, it is necessary to carry out bone grafting procedures. Considering there are various types of grafts and various donor sites. Thus, the aim of this study was to review the literature to some type of graft most commonly used in dentistry. Given the importance of bone reconstruction in oral and maxillofacial surgery, it is necessary to know the viability and influence of biomaterials, or not associated with autogenous grafts in bone repair. Even this, with many qualities, but further studies should be done to achieve each day, a synthetic material compatible with bone tissue lost in adequate amounts without requiring extra-oral surgeries that are considered to be devoted to higher morbidity.

Autogenous bone combined with anorganic bovine bone for maxillary sinus augmentation: Analysis of the osteogenic potential of cells derived from the donor and the grafted sites

Objectives: This study aimed to comparatively evaluate the in vitro osteogenic potential of cells obtained from the mandibular ramus (MR, autogenous bone donor site) and from the maxillary sinus (MS) bone grafted with a mixture of anorganic bovine bone (ABB) and MR prior to titanium implant placement (MS, grafted implant site). Material and methods: Cells were obtained from three patients subjected to MS floor augmentation with a 1: 1 mixture of ABB (GenOx Inorg®) and MR. At the time of the sinus lift procedure and after 8 months, prior to implant placement, bone fragments were taken from MR and MS, respectively, and subjected to trypsin-collagenase digestion for primary cell culturing. Subcultured cells were grown under osteogenic condition for up to 21 days and assayed for proliferation/viability, osteoblast marker mRNA levels, alkaline phosphatase (ALP) activity and calcium content/Alizarin red staining. ALP activity was also determined in primary explant cultures exposed to GenOx Inorg® (1: 1 with MR) for 7 days. Data were compared using either the Mann-Whitney U-test or the Kruskal-Wallis test. Results: MS cultures exhibited a significantly lower osteogenic potential compared with MR cultures, with a progressive increase in cell proliferation together with a decrease in osteoblast markers, reduced ALP activity and calcium content. Exposure of MR-derived primary cultures to GenOx Inorg® inhibited ALP activity. Conclusion: These results suggest that the use of GenOx Inorg® in combination with MR fragments for MS floor augmentation inhibits the osteoblast cell differentiation at the implant site in the long term. © 2013 John Wiley & Sons A/S.

Ecotoxicological assessment of sediments from the Port of Santos and the disposal sites of dredged material

A dragagem dos sedimentos do Canal de Santos é necessária para permitir o trânsito de navios que operam no Porto de Santos. As áreas de disposição do material dragado estão situadas na zona costeira, em frente à Baía de Santos. Este estudo visou avaliar a qualidade dos sedimentos do Canal de Santos e das áreas de disposição atuais e antigas, utilizando testes de toxicidade de sedimento integral com anfípodos e de toxicidade de elutriatos com embriões de ouriço do mar. As amostras do Canal de Santos foram consideradas as mais tóxicas: todas as amostras dessa área foram consideradas significativamente tóxicas. Além disso, algumas amostras das áreas de disposição exibiram toxicidade. Os resultados mostraram, portanto, que os sedimentos apresentam evidências de degradação em sua qualidade, porém novos estudos devem ser conduzidos visando determinar as relações entre contaminação e toxicidade. Os resultados sugerem ainda que a disposição dos sedimentos dragados deva ser reavaliada.

Kinetic Analysis of Gill (Na+,K+)-ATPase Activity in Selected Ontogenetic Stages of the Amazon River Shrimp, (Decapoda, Palaemonidae): Interactions at ATP- and Cation-Binding Sites

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

The bacterial chromosome segregation protein Spo0J spreads along DNA from parS nucleation sites

Regulation of chromosome inheritance is essential to ensure proper transmission of genetic information. To accomplish accurate genome segregation, cells organize their chromosomes and actively separate them prior to cytokinesis. In Bacillus subtilis the Spo0J protein is required for accurate chromosome segregation and it regulates the developmental switch from vegetative growth to sporulation. Spo0J is a DNA-binding protein that recognizes at least eight identified parS sites located near the origin of replication. As judged by fluorescence microscopy, Spo0J forms discrete foci associated with the oriC region of the chromosome throughout the cell cycle. In an attempt to determine the mechanisms utilized by Spo0J to facilitate productive chromosome segregation, we have investigated the DNA binding activity of Spo0J. In vivo we find Spo0J associates with several kilobases of DNA flanking its specific binding sites (parS) through a parS-dependent nucleation event that promotes lateral spreading of Spo0J along the chromosome. Using purified components we find that Spo0J has the ability to coat non-specific DNA substrates. These 'Spo0J domains' provide large structures near oriC that could potentially demark, organize or localize the origin region of the chromosome.