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ObjectiveTo compare two pulp harvesting methods for stem cell expansion, namely, conservative pulpotomy and pulpectomy from exodontia.MethodTen freshly extracted sound third molars from five patients were selected. Five were used in the control group, where pulp harvesting was performed by exodontia and the remaining teeth were used in the test group, where the pulp was harvested by conservative pulpotomy (preserving the tooth). This was a split-mouth design study, where a third molar from one side was randomly allocated into the test group and the contralateral tooth in the control group. After pulp harvesting, the following evaluations were performed: cell morphology, sterility test, immunophenotyping, differentiation assays, first pass live cell counts, time to cryopreservation, and total number of expanded cells at the end of the fourth pass.ResultsRegarding morphology, the cells from both groups presented a fibroblastic phenotype. All samples were sterile. Immunophenotyping demonstrated a positive expression for CD105, CD90, and CD73 and negative expression for CD45 in both groups. Differentiation assays were positive for osteogenic and chondrogenic differentiation in both groups. Regarding live cell counts in the first passage, the control group had 95.8% live cells in the total count and the test group 91.2% (p < 0.05). The time required for cryopreservation was equivalent in both groups 51.6 days and 52.6 days, respectively (p > 0.05). The total number of cells at the end of the fourth passage was 5,286,782 and 5,736,862, respectively (p > 0.05).ConclusionThese results suggest that adult stem cell harvesting from conservative pulpotomy is as effective as the traditional exodontia-based method.

This animal study evaluated the osseointegration level of a new nanotextured titanium surface produced by anodization. Ti-cp micro-implants (1.5 mm diameter by 2.5 mm in length) divided into two groups: titanium nanotextured surface treatment (Test Group) and acid etched surface treatment (Control Group). Surface characterization included morphology analysis using scanning electron microscopy and wettability by measuring contact angle. Sixteen Wistar rats were submitted to two micro implants surgical placement procedures. In each rat, one type of micro implant placed in each tibia. The animals sacrificed after two (T1) and six weeks (T2) post-implantation. After the euthanasia, tibias processed for histomorphometric analysis, which allowed the evaluation of bone to implant contact (BIC) and the bone area fraction occupancy between the threads (BAFO). Our surface analysis data showed that the Control Group exhibited an irregular and non-homogenous topography while the Test Group showed a nanotextured surface. The Test Group showed higher wettability (contact angle = 5.1 ± 0.7°) than the Control Group (contact angle = 75.5 ± 4.6°). Concerning the histomorphometric analysis results for T1, Control and Test groups showed BIC percentages of 41.3 ± 15.2% and 63.1 ± 8.7% (p < 0.05), respectively, and for BAFO, 28.7 ± 13.7% and 54.8 ± 7.5%, respectively (p < 0.05). For T2, the histomorphometric analysis for Control and Test groups showed BIC percentages of 51.2 ± 11.4% and 64.8 ± 7.4% (p < 0.05), respectively and for BAFO, 36.4 ± 10.3% and 57.9 ± 9.3% (p < 0.05), respectively. The findings of the current study confirmed that the novel nanotextured surface exhibited superior wettability, improved peri-implant bone formation, and expedited osseointegration.

Guided bone regeneration involving the use of titanium mesh and platelet-rich fibrin could be a feasible approach in cases of severely atrophic ridges. The purpose of this case report was to present an esthetic and functional rehabilitation in the anterior maxilla with the installation of dental implants in conjunction with guided bone regeneration using titanium mesh and advanced platelet-rich fibrin (A-PRF). A 60-year-old patient presented bone atrophy and partial edentulism in the anterior maxilla. After clinical and cone beam computed tomography assessment, guided bone regeneration was planned using a titanium mesh and A-PRF with xenograft bone. After 8 months of healing, the dental implants were placed with the aid of a surgical guide to obtain accurate 3-dimensional positioning. Prosthetic rehabilitation was carried out with individualized crowns. After 2 years of follow-up, radiographic analysis demonstrated a good quality and density of the bone tissue adjacent to the dental implants. No radiolucent areas were observed, and there were no clinical signs of failure. In cases of severe atrophy, using a titanium mesh and A-PRF proved to be a feasible alternative for bone reconstruction prior to dental implant placement. This approach can aid dental professionals in achieving an ideal implant positioning for rehabilitation with individualized crowns. [ABSTRACT FROM AUTHOR]

For humans to explore and colonize the universe, both engineering and physiological obstacles must be successfully addressed. A major physiological problem is that humans lose bone rapidly in microgravity. Understanding the underlying mechanisms for this bone loss is crucial for designing strategies to ameliorate these effects. Because bone physiology is entangled with other organ systems, and bone loss is a component of human adaptation to microgravity, strategies to reduce bone loss must also account for potential effects on other systems. Here, we consider the receptors involved in normal bone remodeling and how this regulation is altered in low-gravity environments. We examine how single cells, tissues and organs, and humans as a whole are affected by low gravity, and the role of receptors that have been implicated in responses leading to bone loss. These include receptors linking cells to the extracellular matrix and to each other, alterations in the extracellular matrix associated with changes in gravity, and changes in fluid distribution and fluid behavior due to lack of gravity that may have effects on receptor-based signaling shared by bone and other regulatory systems. Inflammatory responses associated with the environment in space, which include microgravity and radiation, can also potentially trigger bone loss. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the clinical, tomographic, and histological performance of collagenated xenogeneic bone blocks (CXBB) in horizontal bone augmentations for implant placement. Five patients with an absence of the 4 upper incisors and an HAC 3 horizontal bone defect, with a remaining of 3 to 5 mm, underwent a bone-grafting procedure with CXBB (test group [TG], n = 5) and autogenous graft (control group [CG], n = 5), with one type of graft used on the right side and other type on the left side. Changes in bone thickness and density (tomographic evaluation), levels of complications (clinically), and distribution pattern between mineralized and nonmineralized tissue (histomorphometrically) were analyzed. Tomographic analysis showed a horizontal bone increase of 4.25 ± 0.78 mm in the TG and 3.08 ± 0.8 mm in the CG between baseline and 8 months postoperatively (P <.05). The horizontal loss between the day of installation of the blocks and 8 months postoperatively was 1.02 ± 0.39 mm for the TG and 1.10 ± 0.71 mm for the CG (P >.05). With regard to bone density, the TG blocks right after installation had 440.2 ± 89.15 HU, and after 8 months, the region reached 730.7 ± 130.98 HU, representing an increase of 29.05%. For the CG blocks, bone density increased from 1052.2 ± 398.35 HU to 1222.5 ± 453.28 HU, representing an increase of 17.03%. The increase in bone density was significantly higher in the TG (P <.05). Clinically, no cases of exposure of the bone blocks and no failure of incorporation were observed. Histomorphometrically, the percentage of mineralized tissue was lower in the TG than in the CG (48.10% ± 2.88% and 53.53% ± 1.05%, respectively), and the opposite was verified for the levels of nonmineralized tissue (52.79% ± 2.88% and 46.47% ± 1.05%, respectively; P <.05). The use of CXBB achieved higher levels of horizontal gain, with lower bone density and lower levels of mineralized tissue when compared with the use of autogenous blocks. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this in vitro study was to determine the minimum placement torque required to attach the transducer (measuring peg) to the implant to provide an accurate assessment of implant stability using resonance frequency analysis. Materials and Methods: One hundred 4 x 11-mm screw-shaped titanium implants were inserted into a uniform polyurethane block with similar density to bone in a standardized surgical protocol. The implants were distributed into 10 groups, with 10 implants each (G1 to G10). In G1, the transducer was manually attached by a female operator and in G2 by a male operator using the manual connector provided by the manufacturer. For the remaining groups (G3 to G10), the transducers were placed using a connector adapted to a digital torque wrench with different torque settings: 3 Ncm (G3), 4 Ncm (G4), 5 Ncm (G5), 6 Ncm (G6), 10 Ncm (G7), 13 Ncm (G8), 17 Ncm (G9), and 20 Ncm (G10). Stability was measured for all groups using the Osstell equipment (Diagnosis of Integration) and the implant stability quotient (ISQ) annotated for statistical comparison between the groups. Results: The mean ± standard deviation ISQ values for groups G1 to G10 were 9.50 ± 5.54, 19.05 ± 2.67, 29.25 ± 4.22, 26.55 ± 5.37, 40.90 ± 0.99, 69.60 ± 2.41, 71.30 ± 0.82, 71.20 ± 1.32, 72.40 ± 0.97, and 70.90 ± 0.88, respectively. Statistical comparisons determined that the amplitudes of the confidence intervals, relative to the standard deviations, were lowest for groups G5, G7, G8, G9, and G10. For the means, the lowest amplitudes of the confidence intervals were observed in G6, G7, G8, G9, and G10. When checking the conjugated confidence intervals (mean and standard deviation), the results were homogenous for G7, G8, G9, and G10. When the torque of 20 Ncm was reached, the connection between the transducer and the implant failed. Conclusion: In this in vitro model experiment, transducer torques between 10 and 17 Ncm appear to be adequate for accurate measurement of implant stability, allowing more precise comparisons without damaging the prosthetic connection in the implant. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the combination of a bone marrow mononuclear fraction with a bone xenograft material in an appositional bone regeneration technique. Materials and Methods: Twelve New Zealand rabbits were randomly divided into two groups of six animals each. Bone reconstruction situations were created using titanium cylinders; these were filled with xenograft in group 1 animals and xenograft enriched with bone marrow mononuclear fraction in group 2 animals. Two cylinders were adapted onto the calvaria of each animal. Bone marrow aspirate was obtained from the tibia of every animal. After 8 weeks, the animals were sacrificed and the parietal bone and cylinders were fixed in 10% formalin for analysis of clinical measurement of the bone volume formed inside the cylinders and histomorphometric evaluation of parameters such as vital mineralized tissue (VMT), nonvital mineralized tissue (NVMT), nonmineralized tissue (NMT), and vital mineralized tissue in contact with titanium (VMTCT). Results: Clinically, groups 1 and 2 demonstrated bone volume gains of 88.29% ± 25.97% and 98.96% ± 0.00%, respectively. Histomorphometry for groups 1 and 2, respectively, demonstrated the following mean values: VMT, 18.96% ± 8.99% and 28.02% ± 8.76%; NVMT, 28.43% ± 2.44% and 25.57% ± 2.33%; NMT, 52.61% ± 10.80% and 46.42% ± 10.06%; and VMTCT, 4.98% ± 4.30% and 27.29% ± 9.58%. Conclusion: The results of this study suggest that the use of the bone marrow mononuclear fraction can improve bone healing and the level of osseointegration. [ABSTRACT FROM AUTHOR]

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Aim: The aim of this study was to analyze and follow-up implants placed in the posterior maxillary regions previously grafted with homologous bone. Materials and Methods: Forty-one grafts with homologous bone blocks were performed in maxillary sinuses, and 121 implants were placed in premolar and molar regions approximately 6 months after the grafts. Patients were followed up for periods varying from 12 to 124 months after rehabilitation. Results: The results showed two implant failures, for a 98.3% success rate during the follow-up period. Discussion: The implants placed had an average torque of 40 N-cm, regardless of the, design, diameter, and length of the implants used. Conclusion: After following up on the implants placed in this study, we concluded that those placed in regions of the maxillary sinuses previously grafted with homologous bone blocks had high long-term success rates and met the functional masticatory requirements. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]