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.

Conditioned Media from Human Pulp Stem Cell Cultures Improve Bone Regeneration in Rat Calvarial Critical-Size Defects.

The aim of this study was to test whether lyophilized conditioned media from human dental pulp mesenchymal stem cell cultures promote the healing of critical-size defects created in the calvaria of rats. Prior to the surgical procedure, the medium in which dental pulp stem cells were cultured was frozen and lyophilized. After general anesthesia, an 8 mm diameter bone defect was created in the calvaria of twenty-four rats. The defects were filled with the following materials: xenograft alone (G1) or xenograft associated with lyophilized conditioned medium (G2). After 14 or 42 days, the animals were euthanized, and the specimens processed for histologic and immunohistochemical analysis. Bone formation at the center of the defect was observed only in the G2 at 42 days. At both timepoints, increased staining for VEGF, a marker for angiogenesis, was observed in G2. Consistent with this, at 14 days, G2 also had a higher number of blood vessels detected by immunostaining with an anti-CD34 antibody. In conclusion, conditioned media from human dental pulp mesenchymal stem cell cultures had a positive effect on the regenerative process in rat critical-size bone defects. Both the formation of bone and enhancement of vascularization were stimulated by the conditioned media.

Sema4D is diminished in leukocyte platelet-rich fibrin and impairs pre-osteoblastic MC3T3-E1 cells' functionality.

OBJECTIVE: Semaphorin 4D (Sema4D) is a coupling factor expressed on osteoclasts that may hinder osteoblast differentiation. Since the leukocyte platelet-rich fibrin (L-PRF) membrane promotes growth factor concentration, this study aims to quantify the amount of Sema4D in L-PRF membranes, and analyze the impact of Sema4D on osteoblast cell function in vitro. DESIGN: Enzyme-linked immunosorbent assay (ELISA) was used to quantify the levels of Sema4D in both L-PRF and whole blood (serum). To analyze the impairment of Sema4D on osteoblasts, MC3T3-E1 cells were induced to osteogenic differentiation and exposed to Sema4D ranging from 10 to 500 ng/ml concentrations. The following parameters were assayed: 1) cell viability by MTT assay after 24, 48, and 72 h; 2) matrix mineralization by Alizarin Red staining after 14 days, 3) Runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN), osteonectin (ONC), bone sialoprotein (BSP) and alkaline phosphatase (ALP) gene expression by qPCR. For all data, the significance level was set at 5%. RESULTS: The amount of Sema4D in the whole blood (serum) was higher than in L-PRF. Osteoblasts exposed to Sema4D at all tested concentrations exhibited a decrease in matrix mineralization formation as well in RUNX-2, OCN, ONC, BSP, and ALP gene expression (p < 0.05). CONCLUSION: The presence of Sema4D, a molecule known for suppressing osteoblast activity, diminishes within L-PRF, enhancing its ability to facilitate bone regeneration.

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.

Stress distribution on implant- supported zirconia crown of maxillary first molar: effect of oblique load on natural and antagonist tooth.

This study evaluated the stress distribution on an implant-supported zirconia crown of a mandibular first molar subjected to oblique loading by occlusal contact with the natural maxillary first molar by using the 3D finite element method. Two virtual models were made to simulate the following situations: (1) occlusion between maxillary and mandibular natural first molars; (2) occlusion between zirconia implant-supported ceramic crown on a mandibular first molar and maxillary natural first molar. The models were designed virtually in a modeling program or CAD (Computer Aided Design) (Rhinoceros). An oblique load of 100 N was uniformly applied to the zirconia framework of the crown. The results were obtained by the Von Mises criterion of stress distribution. Replacement of the mandibular tooth by an implant caused a slight increase in stress on portions of the maxillary tooth roots. The crown of the maxillary model in occlusion with natural antagonist tooth showed 12% less stress when compared with the maxillary (model in occlusion with the) implant-supported crown. The mandibular crown of the implant show 35% more stress when compared with the mandibular antagonist crown on the natural tooth. The presence of the implant to replace the mandibular tooth increased the stresses on the maxillary tooth, especially in the region of the mesial and distal buccal roots.

Barbell Technique: A Novel Approach for Bidirectional Bone Augmentation: Clinical and Tomographic Study.

Horizontal bone augmentation is a common surgical procedure used in implant therapy to achieve adequate bone volume to permit dental implant placement. However, most current techniques are focused on unidirectional bone reconstruction (grafting only on the buccal side). This study was carried out to validate a new device that will permit bidirectional bone augmentation. Ten patients of both sexes (7 women and 3 men), with ages ranging from 29 to 62 years, who needed a bidirectional horizontal bone augmentation in maxilla were separated in accordance with the horizontal alveolar change (HAC) classification published by Pelegrine et al (2018). The patients classified as HAC 3 (ie, containing remaining cancellous bone at the recipient bed) received the Barbell device with xenogeneic biomaterial and a collagen membrane, whereas HAC 4 patients (ie, with no remaining cancellous bone at the recipient bed) received the Barbell device with a mixture of autogenous bone chips and xenogeneic biomaterial covered by a collagen membrane. For each patient, two computerized tomography scans were performed (T0 at baseline and T1 at 6 months postoperative examinations). Mean bone thickness (T0) in the studied sites were 3.25 ± 0.35 in HAC 3 and 1.98 ± 0.5 in HAC 4 patients. The mean bone thickness achieved after 6 months was 7.70 ± 0.89 mm and 8.62 ± 0.89 in HAC 3 and 4, respectively. All grafted sites were able to receive dental implants in adequate prosthetic positions. Based on these results, the use of this novel device permits bidirectional horizontal bone augmentation.

Horizontal Bone Augmentation With Autogenous and Collagenated Xenogeneic Bone Blocks: A Split-Mouth Prospective Clinical, Tomographic, and Histological Pilot Study.

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.

Collagen-chitosan-hydroxyapatite composite scaffolds for bone repair in ovariectomized rats.

Lesions with bone loss may require autologous grafts, which are considered the gold standard; however, natural or synthetic biomaterials are alternatives that can be used in clinical situations that require support for bone neoformation. Collagen and hydroxyapatite have been used for bone repair based on the concept of biomimetics, which can be combined with chitosan, forming a scaffold for cell adhesion and growth. However, osteoporosis caused by gonadal hormone deficiency can thus compromise the expected results of the osseointegration of scaffolds. The aim of this study was to investigate the osteoregenerative capacity of collagen (Co)/chitosan (Ch)/hydroxyapatite (Ha) scaffolds in rats with hormone deficiency caused by experimental bilateral ovariectomy. Forty-two rats were divided into non-ovariectomized (NO) and ovariectomized (O) groups, divided into three subgroups: control (empty defect) and two subgroups receiving collagen/chitosan/hydroxyapatite scaffolds prepared using different methods of hydroxyapatite incorporation, in situ (CoChHa1) and ex situ (CoChHa2). The defect areas were submitted to macroscopic, radiological, and histomorphometric analysis. No inflammatory processes were found in the tibial defect area that would indicate immune rejection of the scaffolds, thus confirming the biocompatibility of the biomaterials. Bone formation starting from the margins of the bone defect were observed in all rats, with a greater volume in the NO groups, particularly the group receiving CoChHa2. Less bone formation was found in the O subgroups when compared to the NO. In conclusion, collagen/chitosan/hydroxyapatite scaffolds stimulate bone growth in vivo but abnormal conditions of bone fragility caused by gonadal hormone deficiency may have delayed the bone repair process.

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)

Osteocalcin and Runx2 Expression in Anterior Maxillary Reconstructions Using Bone Xenografts Associated to Bone Marrow Aspirate Concentrate.

Background: It is known that a large number of mediators involved in osteogenesis can influence bone development and repair; however, whether these mediators could be used as markers of bone maturity has yet to be determined. Aim: To evaluate the expression of osteocalcin (OC) and Runt-related transcription factor 2 (Runx2) in bone biopsies obtained during the reconstruction of atrophic anterior maxillae using particulate bone xenografts with or without association of autogenous bone marrow aspirate concentrate (BMAC). Materials and Methods: Ten patients were distributed into two groups (n = 5), according to the type of grafting material used: Control group (CG), particulate bone xenograft alone, and test group (TG), particulate bone xenograft combined with BMAC. A bone specimen was removed from the graft area 4 months after grafting, before implant placement. The specimens were processed and submitted to immunohistochemical analysis for detection of OC and Runx2. Histomorphometry was used to ascertain the percentage of stained areas in both groups. The Wilcoxon Mann-Whitney U-Test was used in the statistical analysis (P < 0.05). Results: The immunohistochemical analysis revealed a significantly higher OC expression in the TG than in the CG, namely 27.40 ± 1.34% and 11.40 ± 2.70%, respectively (P < 0.05), and a significantly higher Runx2 expression in the TG than in the CG, namely 2.80 ± 0.84% and 0.40 ± 0.55%, respectively (P < 0.05). Conclusion: The OC and Runx2 expression levels were higher when BMAC was associated with the bone xenograft than when it was not.

Comparative analysis of two biomaterials mixed with autogenous bone graft for vertical ridge augmentation: A histomorphometric study in humans.

BACKGROUND: The vertical increase of the alveolar ridge dimension using allograft or xenograft mixed with autogenous bone graft and covered by a nonabsorbable high-density polytetrafluoroethylene (d-PTFE) membrane is well documented in the literature. PURPOSE: The aim of this study was to assess vital mineralized tissue formation in vertical ridge augmentation (VRA) procedures using autogenous bone chips mixed either with an allograft or a xenograft. METHODS: This prospective clinical trial recruited 16 partially edentulous patients to undergo vertical ridge augmentation in one or more sites, making up a total of 24 samples for histological evaluation. Patients were sequentially stratified into Group A (treated with a freeze-dried bone allograft [FDBA] mixed with autogenous bone) or to Group B (treated with a bovine xenograft mixed with autogenous bone). Histological samples were analyzed according to the biomaterial used for VRA. Histological samples were obtained on the same day of membrane removal and implant placement. RESULTS: Thirty-three implants were placed in 16 sites of regenerated bone via VRA, 13 patients with ridge augmentation in the posterior mandible, and 3 patients with VRA in the anterior maxilla. Group A (FDBA + autogenous) and Group B (xenograft + autogenous) showed a percent vital mineralized tissue (VMT) area of 67.64 ± 16.84 and 60.93 ± 18.25, respectively. A significant difference between the two biomaterials was not observed. CONCLUSION: When mixed with autogenous bone, either allografts or xenografts may provide a successful augmentation. Either mixture could serve as reliable alternative in VRA for obtaining a high percentage of VMT.

Influence of Titanium Surface Treatments on Viability of Periodontal Fibroblasts Grown in an Osteogenic Culture Medium.

Background: The integrity of the protective seal provided by the gingiva in direct contact with the implant surface is one of the main factors involved in the prevention of peri-implantitis. Aim: The aim of this study was to assess the viability of periodontal fibroblasts grown in an osteogenic culture medium in contact with titanium surfaces treated either with acid etching alone or with acid etching + anodizing. Materials and Methods: Periodontal fibroblasts grown in an osteogenic culture medium were distributed in a control group, with cells grown in culture bottles, and two experimental groups, with cells grown in contact with titanium disks measuring 6 mm in diameter. The surface of the disks was subjected to acid etching alone (AEG, n = 25) or to acid etching + anodizing (ANG, n = 25), and then evaluated using scanning electron microscopy (SEM). Cell viability was assessed by the [3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium] bromide test on days 1, 2, 3, 7, and 14 of the cell culture. The Mann-Whitney test was used for the statistical analysis (P < 0.05). Results: The SEM assessment revealed that the surface of AEG specimens had micrometric characteristics, whereas the surface of ANG specimens had nanometric characteristics. No significant difference was observed among the groups regarding cell viability at any of the evaluation time points. Conclusion: The titanium surface treatments tested did not affect the viability of periodontal fibroblasts in an osteogenic culture medium.

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.

In Vivo Study of Nasal Bone Reconstruction with Collagen, Elastin and Chitosan Membranes in Abstainer and Alcoholic Rats.

The aim of the present study was to evaluate the use of collagen, elastin, or chitosan biomaterial for bone reconstruction in rats submitted or not to experimental alcoholism. Wistar male rats were divided into eight groups, submitted to chronic alcohol ingestion (G5 to G8) or not (G1 to G4). Nasal bone defects were filled with clot in animals of G1 and G5 and with collagen, elastin, and chitosan grafts in G2/G6, G3/G7, and G4/G8, respectively. Six weeks after, all specimens underwent radiographic, tomographic, and microscopic evaluations. Bone mineral density was lower in the defect area in alcoholic animals compared to the abstainer animals. Bone neoformation was greater in the abstainer groups receiving the elastin membrane and in abstainer and alcoholic rats receiving the chitosan membrane (15.78 ± 1.19, 27.81 ± 0.91, 47.29 ± 0.97, 42.69 ± 1.52, 13.81 ± 1.60, 18.59 ± 1.37, 16.54 ± 0.89, and 37.06 ± 1.17 in G1 to G8, respectively). In conclusion, osteogenesis and bone density were more expressive after the application of the elastin matrix in abstainer animals and of the chitosan matrix in both abstainer and alcoholic animals. Chronic alcohol ingestion resulted in lower bone formation and greater formation of fibrous connective tissue.

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.

Influence of Dental Pulp Harvesting Method on the Viability and Differentiation Capacity of Adult Dental Pulp-Derived Mesenchymal Stem Cells.

OBJECTIVE: To compare two pulp harvesting methods for stem cell expansion, namely, conservative pulpotomy and pulpectomy from exodontia. METHOD: Ten 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. RESULTS: Regarding 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). CONCLUSION: These results suggest that adult stem cell harvesting from conservative pulpotomy is as effective as the traditional exodontia-based method.

In Vivo Biological Behavior of Polymer Scaffolds of Natural Origin in the Bone Repair Process.

Autologous bone grafts, used mainly in extensive bone loss, are considered the gold standard treatment in regenerative medicine, but still have limitations mainly in relation to the amount of bone available, donor area, morbidity and creation of additional surgical area. This fact encourages tissue engineering in relation to the need to develop new biomaterials, from sources other than the individual himself. Therefore, the present study aimed to investigate the effects of an elastin and collagen matrix on the bone repair process in critical size defects in rat calvaria. The animals (Wistar rats, n = 30) were submitted to a surgical procedure to create the bone defect and were divided into three groups: Control Group (CG, n = 10), defects filled with blood clot; E24/37 Group (E24/37, n = 10), defects filled with bovine elastin matrix hydrolyzed for 24 h at 37 °C and C24/25 Group (C24/25, n = 10), defects filled with porcine collagen matrix hydrolyzed for 24 h at 25 °C. Macroscopic and radiographic analyses demonstrated the absence of inflammatory signs and infection. Microtomographical 2D and 3D images showed centripetal bone growth and restricted margins of the bone defect. Histologically, the images confirmed the pattern of bone deposition at the margins of the remaining bone and without complete closure by bone tissue. In the morphometric analysis, the groups E24/37 and C24/25 (13.68 ± 1.44; 53.20 ± 4.47, respectively) showed statistically significant differences in relation to the CG (5.86 ± 2.87). It was concluded that the matrices used as scaffolds are biocompatible and increase the formation of new bone in a critical size defect, with greater formation in the polymer derived from the intestinal serous layer of porcine origin (C24/25).

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.

Can Finger-Generated Force Be Used Reliably to Connect the Transducer for Resonance Frequency Analysis in Determining Implant Stability?

PURPOSE: The purpose of this study was to determine the minimum torque required to attach the transducer to the implant to measure the implant stability quotient (ISQ) with two different devices and to estimate if finger-generated torque would be reliable for this purpose. MATERIALS AND METHODS: One hundred implants were inserted into a uniform polyurethane block. The implants were distributed into 10 groups, with 10 implants each. The transducers were manually attached by a female operator (G female) and by a male operator (G male) using the standard connector provided by the manufacturers. For the remaining groups, the transducers were placed using a connector adapted to a digital torque wrench with different torque settings: 3 Ncm (G 3Ncm), 4 Ncm (G 4Ncm), 5 Ncm (G 5Ncm), 6 Ncm (G 6Ncm), 10 Ncm (G 10Ncm), 13 Ncm (G 13Ncm), 17 Ncm (G 17Ncm), and 20 Ncm (G 20Ncm). The stability was measured for all groups using both the Osstell and the Penguin resonance frequency analyzers. The minimum, medium, and maximum finger grip torque were accessed on 100 volunteers. RESULTS: For Osstell, the conjugated confidence intervals were homogenous for four groups (G 10Ncm, G 13Ncm, G 17Ncm, and G 20Ncm), and for Penguin, they were homogenous for six groups (G 5Ncm, G 6Ncm, G 10Ncm, G 13Ncm, G 17Ncm, and G 20Ncm). The minimum finger-generated force was 2.18 ± 1.05 Ncm, the medium force was 4.25 ± 1.57 Ncm, and the maximum force was 7.51 ± 2.52 Ncm, measuring with a digital torque meter. CONCLUSION: For an accurate measurement of ISQ, the minimum torque necessary to insert the transducer into the implant for Osstell was 10 Ncm, while for Penguin, it was 5 Ncm. Therefore, when using Osstell to assess implant stability, the authors suggest the use of a torque wrench to ensure 10 Ncm of force is applied when tightening the transducer into the implant to obtain accurate stability measurements. When using Penguin, the maximum finger-generated tightening force is enough.