Barbell Technique for Three-Dimensional Bone Augmentation.

Introduction: Appositional bone augmentation is considered a challenging surgical problem to correct for the deficient alveolar ridge. To overcome this challenge, a novel concept was recently published called "Barbell Technique." This technique has been used more commonly for horizontal bone augmentation. To our knowledge, this is the first report on using the Barbell Technique for vertical bone augmentation. Case Report. This report describes and demonstrates the clinical feasibility of the use of this concept in the reconstruction of a tridimensional alveolar ridge defect in the anterior maxilla. Due to the severity of the defect, both hard and soft tissue deficiencies required augmentation. The first surgery involved a soft tissue grafting procedure while in the second surgical procedure, hard tissue augment was performed using the Barbell device to provide both vertical and horizontal support for the hard tissue graft. The donor material consisted of equal volume of xenograft and autogenous bone used to fill the defect and covered with a collagen barrier membrane. After a healing period of 9 months, the site was reopened. Bone formation clinically verified the correction of alveolar bone contour and volume permitted placement of two titanium implants after the removal of Barbell device. Conclusion: This case report demonstrates successful vertical and horizontal bone augmentation of a critical size defect in the anterior maxilla, correcting both hard and soft tissue contours, and providing the tissues needed to support dental implants in the anterior maxilla.

In Vivo Evaluation of Collagen and Chitosan Scaffold, Associated or Not with Stem Cells, in Bone Repair.

Natural polymers are increasingly being used in tissue engineering due to their ability to mimic the extracellular matrix and to act as a scaffold for cell growth, as well as their possible combination with other osteogenic factors, such as mesenchymal stem cells (MSCs) derived from dental pulp, in an attempt to enhance bone regeneration during the healing of a bone defect. Therefore, the aim of this study was to analyze the repair of mandibular defects filled with a new collagen/chitosan scaffold, seeded or not with MSCs derived from dental pulp. Twenty-eight rats were submitted to surgery for creation of a defect in the right mandibular ramus and divided into the following groups: G1 (control group; mandibular defect with clot); G2 (defect filled with dental pulp mesenchymal stem cells-DPSCs); G3 (defect filled with collagen/chitosan scaffold); and G4 (collagen/chitosan scaffold seeded with DPSCs). The analysis of the scaffold microstructure showed a homogenous material with an adequate percentage of porosity. Macroscopic and radiological examination of the defect area after 6 weeks post-surgery revealed the absence of complete repair, as well as absence of signs of infection, which could indicate rejection of the implants. Histomorphometric analysis of the mandibular defect area showed that bone formation occurred in a centripetal fashion, starting from the borders and progressing towards the center of the defect in all groups. Lower bone formation was observed in G1 when compared to the other groups and G2 exhibited greater osteoregenerative capacity, followed by G4 and G3. In conclusion, the scaffold used showed osteoconductivity, no foreign body reaction, malleability and ease of manipulation, but did not obtain promising results for association with DPSCs.

Pulp-Dentin Complex Regeneration with Cell Transplantation Technique Using Stem Cells Derived from Human Deciduous Teeth: Histological and Immunohistochemical Study in Immunosuppressed Rats.

The aim of this study was to histologically verify the performance of pulp-derived stem cells used in the pulp-dentin complex regeneration. Maxillary molars of 12 immunosuppressed rats were divided into two groups: the SC (stem cells) group, and the PBS (just standard phosphate-buffered saline) group. After pulpectomy and canal preparation, the teeth received the designated materials, and the cavities were sealed. After 12 weeks, the animals were euthanized, and the specimens underwent histological processing and qualitative evaluation of intracanal connective tissue, odontoblast-like cells, intracanal mineralized tissue, and periapical inflammatory infiltrate. Immunohistochemical evaluation was performed to detect dentin matrix protein 1 (DMP1). In the PBS group, an amorphous substance and remnants of mineralized tissue were observed throughout the canal, and abundant inflammatory cells were observed in the periapical region. In the SC group, an amorphous substance and remnants of mineralized tissue were observed throughout the canal; odontoblasts-like cells immunopositive for DMP1 and mineral plug were observed in the apical region of the canal; and a mild inflammatory infiltrate, intense vascularization, and neoformation of organized connective tissue were observed in the periapical region. In conclusion, the transplantation of human pulp stem cells promoted partial pulp tissue neoformation in adult rat molars.

Mechanical behavior of implant-supported full-arch prostheses in different locations in the maxilla: 3D-FEA and strain gauge analysis / Comportamento mecânico de próteses de arco inteiro implanto-suportadas em localizações diferentes na maxila: análise 3D-FEA e strain gauge

The maxillary bone restriction can limit the implants position to support a full-arch prosthesis. Objective:Therefore, this study evaluated the biomechanical behavior of a full-arch prosthesis supported by six implants in different configurations: group A (implants inserted in the region of canines, first premolars and second molars), group B (implants inserted in the region of first premolar, first molar and second molar) and group C (implants in second premolar, first premolar and second molar). Material and Methods: The models were analyzed by the finite element method validated by strain gauge. Three types of loads were applied: in the central incisors, first premolars and second molars, obtaining results of von-Mises stress peaks and microstrain. All registered results reported higher stress concentration in the prosthesis of all groups, with group C presenting higher values in all structures when compared to A and B groups. The highest mean microstrain was also observed in group C (288.8 ± 225.2 µÎµ/µÎµ), however, there was no statistically significant difference between the evaluated groups. In both groups, regardless of the magnitude and direction of the load, the maximum von-Mises stresses recorded for implants and prosthesis displacements were lower in group A. Conclusion: It was concluded that an equidistant distribution of implants favors biomechanical behavior of full-arch prostheses supported by implants; and the placement of posterior implants seems to be a viable alternative to rehabilitate totally edentulous individuals. (AU)

A limitação óssea maxilar totais pode limitar o posicionamento dos implantes para suportar uma prótese de arco total. Objetivo: Sendo assim, este estudo avaliou o comportamento biomecânico de uma prótese de arco total suportada por seis implantes em diferentes configurações: grupo A (implantes inseridos na região de caninos, primeiros pré-molares e segundos molares), grupo B (implantes inseridos na região de primeiro pré-molar, primeiro molar e segundo molar) e grupo C (implantes em segundo pré-molar, primeiro pré-molar e segundo molar). Materiais e métodos: Os modelos foram analisados pelo método de elementos finitos validados por extensometria. Foram aplicados três tipos de cargas: nos incisivos centrais, primeiros pré-molares e nos segundos molares, obtendo resultados de picos de tensão de von-Mises e microdeformação. Todos os resultados registrados mostraram maior concentração de tensão na prótese de todos os grupos, sendo que o grupo C apresentou maiores valores em todas as estruturas quando comparado com os grupos A e B. A maior média de microdeformação também foi observada no grupo C (288,8 ± 225,2 µÎµ/µÎµ), no entanto, não houve diferença estatisticamente significativa entre os grupos avaliados. Em todos os grupos, independentemente da magnitude e direção da carga, as tensões máximas de von-Mises registradas para os implantes e deslocamentos de próteses foram menores no grupo A. Conclusão: Concluiu-se que a distribuição de implantes de forma equidistante favorece o desempenho biomecânico das próteses de arco total suportada por implantes; e o posicionamento de implantes posteriores parece ser uma alternativa viável para reabilitar indivíduos densdentados totais. (AU)

Suitability of Chitosan Scaffolds with Carbon Nanotubes for Bone Defects Treated with Photobiomodulation.

Biomaterials have been investigated as an alternative for the treatment of bone defects, such as chitosan/carbon nanotubes scaffolds, which allow cell proliferation. However, bone regeneration can be accelerated by electrotherapeutic resources that act on bone metabolism, such as low-level laser therapy (LLLT). Thus, this study evaluated the regeneration of bone lesions grafted with chitosan/carbon nanotubes scaffolds and associated with LLLT. For this, a defect (3 mm) was created in the femur of thirty rats, which were divided into 6 groups: Control (G1/Control), LLLT (G2/Laser), Chitosan/Carbon Nanotubes (G3/C+CNTs), Chitosan/Carbon Nanotubes with LLLT (G4/C+CNTs+L), Mineralized Chitosan/Carbon Nanotubes (G5/C+CNTsM) and Mineralized Chitosan/Carbon Nanotubes with LLLT (G6/C+CNTsM+L). After 5 weeks, the biocompatibility of the chitosan/carbon nanotubes scaffolds was observed, with the absence of inflammatory infiltrates and fibrotic tissue. Bone neoformation was denser, thicker and voluminous in G6/C+CNTsM+L. Histomorphometric analyses showed that the relative percentage and standard deviations (mean ± SD) of new bone formation in groups G1 to G6 were 59.93 ± 3.04a (G1/Control), 70.83 ± 1.21b (G2/Laser), 70.09 ± 4.31b (G3/C+CNTs), 81.6 ± 5.74c (G4/C+CNTs+L), 81.4 ± 4.57c (G5/C+CNTsM) and 91.3 ± 4.81d (G6/C+CNTsM+L), respectively, with G6 showing a significant difference in relation to the other groups (a ≠ b ≠ c ≠ d; p < 0.05). Immunohistochemistry also revealed good expression of osteocalcin (OC), osteopontin (OP) and vascular endothelial growth factor (VEGF). It was concluded that chitosan-based carbon nanotube materials combined with LLLT effectively stimulated the bone healing process.

The possible impact of COVID-19 pandemic on dental implant therapy: narrative review / O possível impacto da pandemia de covid-19 na terapia com implantes dentários: revisão narrativa

ABSTRACT The COVID-19 has challenged the professions and Implantology also has its challenges in the pandemic. Several factors can interfere with the osseointegration process and more associated factors, greater the interference risks. Risk assessment in the therapy indication is the main decision to define the best technique, the best biomaterial, the best surgical access and the best moment to intervene. The purpose of this review was to investigate and synthesize the scientific evidence on the factors that may interfere with dental implant therapy in the midst of pandemic. The literature was reviewed in databases such as PubMed, Web of Science, Sciello and Google Scholar using the keywords "COVID-19", "pandemic", "risk factors", "impact factor", "dental implants", "dentistry", "oral health", "osseointegration", "bone metabolism", "drug risk factors", "chronic stress", "antidepressants", "zinc", "hydroxychloroquine", "ivermectin", "vitamins", "corticosteroids", "surgical risks" and "disinfection". The present review showed that chronic stress and depression caused by the pandemic, the consequent use of antidepressants, the use of prophylactic and therapeutic drugs such zinc, vitamin D, hydroxychloroquine and corticosteroids, can interfere with bone metabolism and consequently in osseointegration establishment and/or maintenance. Any osseointegrable biomaterial can be influenced by systemic factors and drugs' actions that can affect the homeostasis of the inflammatory process, cell proliferation and bone remodeling. These factors' influence on dental implant therapy should be investigated through new reviews, observational studies and randomized clinical trial.

RESUMO A COVID-19 desafiou as profissões e a Implantodontia também tem seus desafios na pandemia. Vários fatores podem interferir no processo de osseointegração e quanto mais fatores associados, maiores os riscos de interferência. A avaliação do risco na indicação da terapia é a principal decisão para definir a melhor técnica, o melhor biomaterial, o melhor acesso cirúrgico e o melhor momento para intervenção. O objetivo desta revisão foi investigar e sintetizar as evidências científicas sobre os fatores que podem interferir na terapia com implantes bucais em meio a uma pandemia. A literatura foi revisada em bancos de dados como PubMed, Web of Science, Sciello e Google Scholar usando as palavras-chave "COVID-19", "pandemia", "fatores de risco", "fator de impacto", "implantes dentários", "odontologia", "saúde bucal", "osseointegração", "metabolismo ósseo", "fatores de risco medicamentosos", "estresse crônico", "antidepressivos", "zinco", "hidroxicloroquina", "ivermectina", "vitaminas", "corticosteróides", "riscos cirúrgicos" e "desinfecção". A presente revisão mostrou que o estresse crônico e a depressão causados pela pandemia, o consequente uso de antidepressivos, o uso de drogas profiláticas e terapêuticas como zinco, vitamina D, hidroxicloroquina e corticosteroides, podem interferir no metabolismo ósseo e consequentemente no estabelecimento da osseointegração e/ou sua manutenção. Qualquer biomaterial osseointegrável pode ser influenciado por fatores sistêmicos e ações de drogas que podem afetar a homeostase do processo inflamatório, proliferação celular e remodelação óssea. A influência desses fatores na terapia com implantes dentários deve ser investigada por meio de novas revisões, estudos observacionais e ensaios clínicos randomizados.

Bone marrow aspirate concentrate and platelet-rich fibrin in fresh extraction sockets: A histomorphometric and immunohistochemical study in humans.

The aim of this study was to evaluate the level of mineralized tissue and expression of bone markers in sockets grafted with platelet-rich fibrin and bone marrow aspirate concentrate (BMAC). Patients requiring extraction of one maxillary anterior tooth were randomized into three groups. After tooth extraction, the sockets in the control group (CG) were permitted to fill with blood clot. In the platelet-rich fibrin group (PRFG), after blood processing, the sockets were grafted with PRF plug. In the bone marrow aspirate concentrate combined with platelet-rich fibrin group (BM/PG), after blood and bone marrow processing, the sockets were grafted with a mixture of PRF plug and BMAC. After 6 months, the sites were reopened and bone cores were harvested and prepared for histomorphometric and immunohistochemical evaluation. The following levels were measured: mineralized tissue, expression of RUNX-2, and osteocalcin. Fifteen patients were included in this study. The histomorphometric analysis showed a more pronounced level of mineralized tissue in PRFG and BM/PG (54.20 ± 4.31% and 64.70 ± 6.74%, respectively) when compared with CG (40.60 ± 5.98%) (p = 0.0283 and p = 0.0090, respectively). The expression of RUNX-2 was very low in BM/PG (0.80 ± 0.84%) and absent in CG and PRFG (p = 0.0528). Osteocalcin expression was higher for BM/PG (23.40 ± 1.52%) when compared with CG and PRFG (18.40 ± 2.07% and 16.20 ± 1.92%, respectively) (p = 0.0117 and p = 0.0088, respectively). This preliminary study indicates that clinical use of bone marrow aspirate concentrate, when combined with platelet-rich fibrin as a carrier, might have some potential to increase mineralization in fresh extraction sockets.

Horizontal Bone Reconstruction on sites with different amounts of native bone: a retrospective study

Abstract: The lack of guidelines for bone augmentation procedures might compromise decision making in implantology. The objective of this study was to perform a retrospective study to verify the outcomes of horizontal bone reconstruction in implant dentistry with different types of materials and amounts of native bone in the recipient bed to allow for a new guideline for horizontal bone reconstruction. One hundred preoperative CT scans were retrospectively evaluated and categorized in accordance to horizontal bone defects as presence (Group P) or absence (Group A) of cancellous bone in the recipient bed. Different approaches were used to treat the edentulous ridge and the outcomes were defined either as satisfactory or unsatisfactory regarding the possibility of implant placement. The percentage distribution of the patients according to the presence or absence of cancellous bone was 92% for Group P and 8% for Group A. In Group P, 98% of the patients had satisfactory outcomes, and the use of autografts had 100% of satisfactory outcomes in this group. In Group A, 37.5% of the patients had satisfactory outcomes, and the use of autografts also yielded 100% of satisfactory outcomes. The use of allografts and xenografts in Group A had 0% and 33.3% of satisfactory outcomes, respectively. Therefore, it seems reasonable to speculate that the presence of cancellous bone might be predictive and predictable when the decision includes bone substitutes. In cases of absence of cancellous bone in the recipient bed, the use of a vitalized graft seems to be mandatory.

Use of Bone Allograft With or Without Bone Marrow Aspirate Concentrate in Appositional Reconstructions: A Tomographic and Histomorphometric Study.

OBJECTIVES: To evaluate bone allograft associated to bone marrow aspirate concentrate (BMAC), in maxillary reconstructions. MATERIALS AND METHODS: Ten patients with alveolar bone deficiency in the anterior maxilla were randomly divided into control group (CG) and test group (TG). A bone block allograft was placed in both groups, but the graft was impregnated with BMAC only in TG. Computed tomography was performed 7 days (T1) and 6 months (T2) after the grafting procedure, and volume and bone density measurements were carried out. Histomorphometric analysis was performed at T2. RESULTS: Bone volume loss from T1 to T2 was significant only in TG. The bone density in the buccal region of the graft was significantly higher in TG than in CG. There was no significant difference between the groups, in respect to mineralized tissue (MT) and nonmineralized tissue (NMT), in that MT values were 37.77% ± 15.19% and 43.85% ± 10.94%, and NMT values were 62.15% ± 14.90% and 56.30% ± 10.72%, respectively, for CG and TG. The intragroup difference for the MT/NMT ratio was statistically significant in CG but not significant in TG. CONCLUSIONS: The use of BMAC resulted in an improved pattern of bone formation, with higher bone density in the peripheral regions of the graft.

Comparative Study Between Mesenchymal Stem Cells Derived from Bone Marrow and from Adipose Tissue, Associated with Xenograft, in Appositional Reconstructions: Histomorphometric Study in Rabbit Calvaria.

PURPOSE: This study analyzed the use of bone marrow-derived mesenchymal stem cells and adipose tissue-derived stem cells, associated with xenograft, in appositional reconstructions in rabbit calvaria using histomorphometry. MATERIALS AND METHODS: Fifteen New Zealand rabbits, weighing 3.5 to 4.0 kg and aged between 10 and 12 months, were randomly divided into three groups. Appositional bone reconstruction situations were created in the calvaria of the animals using titanium cylinders, fitted with titanium occlusive caps. Bone decortication was performed to promote bleeding. Inside the cylinders, only xenograft was positioned in the control group (CG; n = 5); xenograft combined with mesenchymal bone marrow-derived stem cells was positioned in group 1 (G1; n = 5), and a xenograft combined with adult mesenchymal stem cells derived from adipose tissue was positioned in group 2 (G2; n = 5). After 56 days, all rabbits were euthanized and their parietal bones processed for histomorphometric analysis, and the following parameters were evaluated: newly formed bone; residual graft particles; soft tissue; vital bone titanium contact, also called the level of osseointegration; and the level of bone volume contained inside the cylinders, also called the internal bone volume. RESULTS: The histomorphometric study revealed the following for CG, G1, and G2: newly formed bone of 18.96% ± 9.00%, 27.88% ± 9.98%, and 22.32% ± 7.45%; residual graft particles of 28.43% ± 2.44%, 23.31% ± 3.11%, and 27.58% ± 3.98%; soft tissue of 52.61% ± 10.80%, 50.23% ± 8.72%, and 49.90% ± 8.76%; vital bone titanium contact of 4.98% ± 4.30%, 34.91% ± 7.82%, and 20.87% ± 5.43%; and internal bone volume of 88.36% ± 25.97%, 98.73% ± 19.05%, and 98.52% ± 19.87%, respectively. No statistical difference between groups for newly formed bone, residual graft particles, soft tissue, and internal bone volume (P > .05) were verified. CONCLUSION: Regarding vital bone titanium contact, it was observed that the use of bone marrow mesenchymal stem cells, when compared with the adipose mesenchymal stem cells, showed the highest level of osseointegration, and both of them obtained superior levels to the xenograft alone.

Implantes cerâmicos em casos estéticos: uma nova possibilidade clínica / Dental ceramic implants in aesthetic cases: a new clinical possibility

A substituição de um elemento dental por um implante em pacientes que apresentam tecido gengival delgado gera uma preocupação devido à translucidez gengival, onde a coloração acinzentada do titânio pode levar ao fracasso estético do tratamento. Desta maneira, os implantes de zircônia se diferenciam principalmente por sua coloração clara, a qual se aproxima das características de cor da raiz, e por sua biocompatibilidade, além de possibilitarem a escolha do paciente por um tratamento totalmente livre de metal. Portanto, este relato de caso clínico demonstrou uma inovação técnica por meio da utilização de um implante confeccionado em zircônia para solução de um caso clínico de alta complexibilidade estética em uma paciente jovem, com fenótipo gengival delgado e alto grau de exigência estética. O caso foi finalizado com prótese cimentada e facetas metal free confeccionadas por meio de cerâmica injetada. Após a finalização do caso, concluiu-se que, apesar da desvantagem relacionada à sensibilidade técnica, o implante confeccionado em zircônia possibilitou a solução estética deste caso clínico de fenótipo gengival delgado, sem a necessidade de utilização de enxertos gengivais.

The replacement of a dental element in patients with thin gingival tissue generates a concern due to gingival translucency, where the titanium gray coloration can lead to failure of the treatment. Thus, the zirconia implants are distinguished primarily by their coloration and their biocompatibility, in addition to enabling the selection of a totally metal-free treatment. Therefore, this clinical report, showed an innovative technique using a zirconia implant in a clinical situation with high complex esthetic needs for in a young patient with thin gingival phenotype and high level of aesthetic requirement. The clinical case was concluded with cemented prosthesis and metal-free veneers made by pressed ceramics. After the end of the case, it was concluded that, despite the disadvantage related to the technical sensitivity, the zirconia implant provided an aesthetic solution of this clinical case of thin gingival phenotype, without the need of gingival grafts.

Homologous transplantation with fresh frozen bone for dental implant placement can induce HLA sensitization: a preliminary study.

It has been related in orthopedic surgeries the HLA sensitization. Thus, we evaluate if the use of fresh-frozen homologous bone (FFHB) for dental implant placement induce anti-HLA sensitization. Six patients were treated with FFHB corticocancellous block grafts. After 6 months, bone biopsies were harvested during implant placement to allow histomorphometric analysis. Vital mineralized tissue (VMT), non-vital mineralized tissue (NVMT) and non-mineralized tissue (NMT) were quantified histomorphometrically. Peripheral blood was collected from the patients before FFHB placement and 6 months after the surgery for anti-HLA analysis. The histomorphometric analysis showed the presence of VMT, NVMT and NMT in 45.56 ± 15.72 %, 14.16 ± 13.39 % and 40.29 ± 12.60 %, respectively. The baseline and 6 months postoperative CTs revealed bone thickness in the order of 5.66 ± 0.67 mm and 8.71 ± 1.52 mm (3.05 ± 1.39 mm). The anti-HLA analysis revealed that two of the six patients (33.3 %) became sensitized, however this was not associated with any FFHB incorporation loss (p > 0.05). A total of 24 implants were placed all of which were osseointegrated after 6 months. Although FFHB-related HLA sensitization does not appear to affect bone incorporation when treating insufficient bone thickness for implant placement, further follow-up is required to determine whether there is an association between HLA sensitization and long-term graft survival.

Can bone marrow aspirate concentrate change the mineralization pattern of the anterior maxilla treated with xenografts? A preliminary study.

OBJECTIVE: To evaluate bony reconstruction of the atrophic anterior maxilla using particulate grafts with or without autologous bone marrow aspirate concentrate (BMAC). MATERIALS AND METHODS: Eight patients with atrophy of the anterior maxilla due to teeth loss were selected and split into groups according to the type of material used: Control Group (CG) (n = 4) - particulate xenograft only and Test Group (TG) (n = 4) - a combination of particulate xenograft and BMAC. Both groups received a collagen membrane to cover the xenograft. After 4 months, during implant placement, a sample of bone was removed from the graft area using a 2 mm diameter trephine bur. The specimens were fixed and preserved for histomorphometric evaluation, which included the following parameters: Mineralized tissue (MT) and non-MT (NMT). Cone beam computed tomography was performed at 3 time intervals to measure bone thickness: (1) Before grafting, (2) 4 months and (3) 8 months postgrafting, using localized bone gain (mm) as the outcome variable. RESULTS: Tomographic analysis revealed bone gain in CG of 3.78 ± 1.35 mm and 4.34 ± 1.58 mm at 4 and 8 months, respectively. TG showed an increase of 3.79 ± 0.52 mm and 4.09 ± 1.33 mm after 4 and 8 months, respectively. Histomorphometric analysis revealed that, for CG, MT- and NMT-related values were 52.3% ± 16.78% and 47.70% ± 5.55%, respectively, whereas for TG, they were 65.04% ± 20.98% and 34.96 ± 10.38, respectively. CONCLUSION: Although radiographic bone gain appeared similar between the groups, the use of BMAC obtained via the BMAC(®) method revealed an increased mineralization trend in the anterior maxilla. It must be highlighted, however, that this is a preliminary study with a relatively small sample population and further studies with larger sample sizes are needed to verify these results.

Ectopic Implantation of Hydroxyapatite Xenograft Scaffold Loaded with Bone Marrow Aspirate Concentrate or Osteodifferentiated Bone Marrow Mesenchymal Stem Cells: A Pilot Study in Mice.

PURPOSE: To evaluate the influence of bone marrow cells in the bone formation in an ectopic subcutaneous model in mice. MATERIALS AND METHODS: Six BALB/c mice were divided into three groups of two each. In all groups, xenograft was implanted subcutaneously. In the negative control group, the xenograft was hydrated with saline solution. In the positive control group, the xenograft was embedded with osteodifferentiated adult mesenchymal stem cells derived from the bone marrow. In the experimental group, the xenograft was embedded with bone marrow aspirate concentrate. After 4 weeks, the animals were sacrificed and prepared for histologic, histomorphometric, and immunohistochemical analysis. The following tissues were evaluated: preosteoid tissue, loose connective tissue, and remaining xenograft particles. RESULTS: There was a statistically significant difference (P = .008) in the preosteoid tissue area between the negative control group (0 ± 0%) and the other two groups, with 42 ± 11% for the experimental group and 56 ± 5% for the positive control group. Similarly, there was a statistically significant difference (P = .006) in the loose connective tissue area between the negative control group (49 ± 18%) and the other two groups, with 3 ± 9% for the experimental group and 0 ± 0% for the positive control group. Regarding the xenograft area, there was not a statistically significant difference between the three groups (P = .143). CONCLUSION: The use of a mineralized scaffold loaded with either concentrated bone marrow aspirate or with osteogenically induced bone marrow mesenchymal stem cells favored the formation of osteoid tissue as opposed to the scaffold alone.

Double Centrifugation Versus Single Centrifugation of Bone Marrow Aspirate Concentrate in Sinus Floor Elevation: A Pilot Study.

PURPOSE: To evaluate the regenerative results of the addition of bone marrow aspirate concentrate, using a single or double centrifugation protocol, to a xenogeneic bone graft in sinus floor elevation. MATERIALS AND METHODS: Using a randomized, controlled pilot study design in 15 consecutive patients, sinus floor elevation procedures were performed with a xenogenous bone graft alone (control group, CG) or associated with bone marrow aspirate concentrate obtained by single centrifugation (single centrifugation group, SCG) or double centrifugation (double centrifugation group, DCG). In the patients in the single and double centrifugation groups, bone marrow was harvested from the iliac bone. Six months after the grafting procedures, bone biopsy specimens were obtained during implant placement and were analyzed by histomorphometry. RESULTS: Histomorphometric analysis revealed a great amount of vital mineralized tissue in SCG followed by DCG when compared with the CG (38.44 ± 12.34%, 34.63 ± 9.84%, and 27.30 ± 5.55%, respectively). SCG and DCG presented smaller amounts of nonvital mineralized tissue when compared with the CG (13.70 ± 7.50%, 19.63 ± 8.35%, and 22.79 ± 9.60%, respectively), thus presenting higher levels of resorption. Although these differences were not statistically significant (P > .05), a tendency toward bone gain in the experimental groups (SCG and DCG) was found. All groups (SCG, DCG, and CG) showed similar levels of nonmineralized tissue (47.87 ± 6.31%, 45.73 ± 7.33%, and 49.90 ± 7.64%, respectively). CONCLUSION: This pilot study indicates that the clinical use of bone marrow aspirate concentrate, obtained by either a single or double centrifugation process, combined with a xenograft for maxillary sinus elevation seems to result in more adequate bone repair. However, clinical trials with a larger number of patients are required.

Adipose mesenchymal stem cells associated with xenograft in a guided bone regeneration model: a histomorphometric study in rabbit calvaria.

PURPOSE: In spite of their osteoconductive potential, the biomaterials used as substitutes for an autologous graft do not show osteoinductive or osteogenic potential. This study evaluated the association of adult mesenchymal stem cells derived from adipose tissue with xenogenic bone graft in bone regeneration in rabbit calvaria. MATERIALS AND METHODS: Mesenchymal stem cells were harvested from adipose tissue from 12 animals. These cells, combined with hydroxyapatite, were implanted in 12-mm bilateral bone defects created in the calvaria of six rabbits (test group [TG]), whereas only hydroxyapatite was implanted in the defects created in another group of six animals (control group [CG]). One grafted side of each animal was covered by a collagen membrane. After 8 weeks, the animals were sacrificed, and the region of the bone defects was removed and evaluated using histomorphometry and immunohistochemistry. RESULTS: The TG showed higher amounts (P < .05) of vital mineralized tissue and nonvital mineralized tissue, 28.24% ± 6.17% and 27.79% ± 2.72%, respectively, compared with the CG, 13.06% ± 5.24% and 13.52% ± 3.00%, respectively. In TG, no difference was observed (P < .05) in the amount of mineralized tissue between the side that was covered by the membrane vs the side without membrane coverage. On the other hand, a statistically significant difference (P < .05) was observed in the CG with regard to the amount of mineralized tissue between the sides with and without membrane coverage. CONCLUSION: These observations suggest that the association of mesenchymal stem cells derived from adipose tissue with a xenogenic bone graft was capable of promoting better bone regeneration compared with the use of a xenograft alone. Use of a membrane did not produce an increase in the regenerative potential for the TG, in contrast to the CG.

Repair of critical-size bone defects using bone marrow stem cells or autogenous bone with or without collagen membrane: a histomorphometric study in rabbit calvaria.

PURPOSE: The aim of this study was to evaluate bone healing after the use of a xenograft scaffold enriched with bone marrow mesenchymal stem cells (BM-MSCs), an autogenous bone graft, or the scaffold without BM-MSCs. MATERIALS AND METHODS: Eighteen rabbits were used for this study; bilateral 12-mm-diameter defects were created in the animals' parietal bones. The bilateral defects were filled with a xenograft enriched with BM-MSCs (test group [TG]), with autogenous bone graft (positive control group [PCG]), or with a xenograft alone (negative control group [NCG]). In all groups, randomly, one defect was covered with a collagen membrane. The rabbits were sacrificed 8 weeks after surgery, and their parietal bones were harvested and analyzed histomorphometrically. RESULTS: Within the PCG and the NCG, the defects covered with the barrier membrane showed better bone healing. In the TG, the defects covered with the barrier membrane did not show better bone healing (intragroup comparisons by Wilcoxon and Friedman tests for paired data). TG showed percentage of mineralized tissue (MT) of 56.03% ± 3.49% with membrane and 57.71% ± 5.31% without membrane. PCG showed MT of 55.13% ± 4.83% and 49.69% ± 3.81% with and without membrane, respectively, and NCG showed MT of 26.77% ± 7.29% and 19.67% ± 2.66% with and without membrane, respectively. CONCLUSION: Both autogenous bone graft and a xenograft enriched with BM-MSCs were equally effective for bone reconstruction and better than the xenograft alone. The use of a barrier membrane seemed to have a synergistic effect on bone healing in PCG and NCG but not in TG.

O uso de ossos alógenos para reconstrução dos maxilares pode induzir anticorpos anti-HLA / The use of allogeneic bone for jaw reconstruction can induce anti-HLA antibodies

Uma das maiores controvérsias relacionadas ao uso de osso alógeno relaciona-se à possível sensibilização imunogênica do paciente receptor. Isso, teoricamente, poderia causar rejeição, incorporação óssea lenta, osteólise, erosões ósseas, degeneração articular, infecção e fratura. Existem na literatura alguns trabalhos demonstrando indícios de sensibilização imunológica frente ao uso dos enxertos ósseos alógenos frescos congelados, com sensibilização da molécula HLA doador-específico. No entanto, há carência de trabalhos científicos que avaliem as possibilidades de sensibilização em humanos após transplante ósseo para fins de reconstrução, para posicionamento de implante dentário. Nosso grupo demonstrou em um trabalho recente a sensibilização para HLA em 33,3% dos pacientes receptores de transplante ósseo córtico-medular, porém, não existiu repercussão significativa da sensibilização na incorporação do enxerto, já que em todos os indivíduos da pesquisa os enxertos apresentaram boa incorporação e remodelação. Apesar da ausência de influência da sensibilização por HLA na incorporação dos enxertos ósseos, deve-se ponderar que uma parcela significativa dos pacientes (33,3%) foi sensibilizada, o que poderia acentuar a rejeição a futuros transplantes, como de fígado ou coração, portadores dos mesmos antígenos HLA (second-set rejection). Faz-se necessário o aprofundamento das investigações científicas sobre a possibilidade de sensibilização dos pacientes receptores de transplante ósseo para fins de reabilitação dentária por meio de implantes.

There is much controversy regarding the use of allogeneic bone in relation to the risk of immunogenic sensitization of the host. This could increase the chances of graft rejection, slow bone incorporation, osteolysis, bony erosions, joint degeneration, infection and fracture. Some studies have shown evidence of immunological sensitization, when using fresh frozen allogeneic bone grafts, against the donor-specific HLA molecule. However, there are only a few studies assessing the risk of sensitization in humans after bone grafting for bone reconstruction prior to dental implant placement. Our group has recently demonstrated a 33.3% rate of HLA sensitization in patients receiving a corticancellous bone graft, however, with no significant effect on graft incorporation, since all subjects in the study showed adequate incorporation and bone remodeling. Despite there being no influence of HLA sensitization in bone graft incorporation, it should be highlighted that a significant portion of patients (33.3%) was sensitized, which could jeopardize future transplants, such as liver or heart, from donors with the same HLA type (second-set rejection). Further investigation is necessary on the sensitization risk among patients receiving bone transplant for the purpose of dental rehabilitation using implants.

Instalação de implante com carga imediata através de um sistema de cirurgia guiada de alta precisão (DIOnavi) / Single implant and immediate loading with a high precision guided surgical system (DIOnavi) – a case report

Os avanços na Implantodontia em busca de resultados previsíveis que possam alinhar estética e função têm levado ao desenvolvimento de sistemas virtuais de planejamento e confecção de guias computadorizados. As cirurgias sem retalho promovem maior conforto aos pacientes, além de apresentarem melhores resultados na manutenção da perda óssea. Entretanto, alguns sistemas ainda apresentam limitações, o que pode levar a diferenças entre o planejamento e o resultado final. Este trabalho teve como objetivo apresentar um caso clínico de instalação de implante com ativação imediata, através do sistema de tecnologia digital de alta precisão DIOnavi (Busan, Coreia). Através de imagens obtidas em tomografias computadorizadas e escaneamento intraoral, o planejamento foi realizado através de um software e um guia cirúrgico, obtido a partir de impressão 3D. Após a instalação do implante, foi instalado um abutment personalizado em titânio e uma coroa provisória cimentada, ambos previamente preparados. O sistema se mostrou eficiente quanto à precisão dos instrumentos e componentes, podendo ser aplicado em diversas situações clínicas, em vista das características.

Advances on implant dentistry aiming predictable results on esthetics and function has led to the development of virtual planning systems and fabrication of computerized surgical guides. Flapless procedures provide more comfort and better results regarding bone loss preservation. However, some systems still have limitations, which can result on differences when the initial and final outcomes are compared. This paper presents a clinical case of immediate implant placement and function using the high-precision digital technology system (DIOnavi, Busan Korea). By means of CBCT and intra-oral scanning, a computer program was used to idealize the surgical guide, with the digital information sent to a 3D-printing machine. After implant placement, the pre-fabricated customized titanium abutment and the cement-retained provisional crown were delivered. This system demonstrated effi ciency related to precision of surgical and prosthetic components and can be recommended for several clinical situations.

Fração mononuclear da medula óssea para reconstrução óssea em levantamento de seio maxilar / Stem cells for bone reconstruction in sinus lifting

Introdução: a demanda por procedimentos de enxertia óssea apresenta um crescimento substancial na área de reabilitação bucal. Entretanto, os pacientes dispostos a se submeter às cirurgias reconstrutivas procuram por procedimentos menos invasivos e com um pós-operatório menos mórbido. Técnicas de reconstrução óssea menos invasivas utilizam, tradicionalmente, substitutos ósseos no sentido de alcançar esses objetivos. No entanto, novos estudos voltados à engenharia tecidual apresentam as células-tronco da medula óssea, em associação a substitutos ósseos, como potencial de melhoramento das características biológicas dos materiais de enxertia. Objetivo: apresentar um caso clínico com a utilização de um concentrado do aspirado da medula óssea autógena (com isolamento da fração mononuclear da medula óssea), associado ao Bio-Oss em um procedimento de levantamento de seio maxilar. Resultados: decorridos cinco meses do procedimento de enxertia composta (Bio-Oss + concentrado de células-tronco medulares),, foram removidas biópsias ósseas durante a cirurgia de instalação dos implantes. Após processamento, as imagens histológicas apresentaram grande quantidade de tecido mineralizado vital para um pós-operatório de cinco meses. Conclusão: o uso do concentrado da fração mononuclear da medula óssea associado ao substituto ósseo xenógeno Bio-Oss em levantamento de seio maxilar parece repercutir em adequado reparo ósseo, culminando em um menor tempo de cicatrização óssea. Porém, estudos clínicos prospectivos randomizados devem ser executados...

Introduction: The demand for bone reconstruction in oral rehabilitation has been growing substantially. However, patients willing to undergo reconstructive surgery want less invasive procedures with less postoperative morbidity. Less invasive bone reconstruction techniques have used bone substitutes to achieve these objectives. Nevertheless, recent studies about tissue engineering have demonstrated that stem cells, in combination with bone grafts, may potentially improve the biological characteristics of grafting material. Objective: To describe a clinical case of sinus elevation using autologous bone marrow aspirate resulting from the isolation of a bone marrow mononuclear fraction combined with Bio-Oss. Results: Five months after the combined grafting procedure (Bio-Oss + bone marrow stem cells), bone biopsies were harvested during implant placement surgery. Histological images revealed a large amount of vital mineralized tissue for a 5-month postoperative time. Conclusion: The clinical use of bone marrow mononuclear fraction combined with Bio-Oss - a xenogeneic bone substitute - in maxillary sinus elevation seems to result in good bone repair and shorter healing time...