Purpose: Several scaffolds and cell sources are being investigated for cartilage regeneration. The aim of the study was to prepare nanocellulose-based thermosensitive injectable hydrogel scaffolds and assess their potential as 3D scaffolds allowing the chondrogenic differentiation of embedded human dental pulp stem and progenitor cells (hDPSCs). Materials and Methods: The hydrogel-forming solutions were prepared by adding βglycerophosphate (GP) to chitosan (CS) at different ratios. Nanocellulose (NC) suspension was produced from hemp hurd then added dropwise to the CS/GP mixture. In vitro characterization of the prepared hydrogels involved optimizing gelation and degradation time, massswelling ratio, and rheological properties. The hydrogel with optimal characteristics, NC-CS /GP-21, was selected for further investigation including assessment of biocompatibility. The chondrogenesis ability of hDPSCs embedded in NC-CS/GP-21 hydrogel was investigated in vitro and compared to that of bone marrow-derived mesenchymal stem cells (BMSCs), then was confirmed in vivo in 12 adult Sprague Dawley rats. Results: The selected hydrogel showed stability in culture media, had a gelation time of 2.8 minutes, showed a highly porous microstructure by scanning electron microscope, and was morphologically intact in vivo for 14 days after injection. Histological and immunohistochemical analyses and real-time PCR confirmed the chondrogenesis ability of hDPSCs embedded in NC-CS/GP-21 hydrogel. Conclusion: Our results suggest that nanocellulose-chitosan thermosensitive hydrogel is a biocompatible, injectable, mechanically stable and slowly degradable scaffold. hDPSCs embedded in NC-CS/GP-21 hydrogel is a promising, minimally invasive, stem cell-based strategy for cartilage regeneration.
Resuming regular clinical activities at dental premises after the COVID-19 lockdown period or post COVID-19 is likely to be a challenge for all dental institutes. When returning to the dental practice or training, staff and students alike should abide by the new rules and regulations. In the process of controlling viral spread, clinical dental facilities face a higher risk of disease transmission among patients as well as clinical and non-clinical staff. Aerosols formation and diffusion into the surrounding air can be a real concern of viral transmission, if no protective measures are established. We aim in this review to present the currently implemented measures and propose changes in clinical dental facilities to minimize the risk of transmission. Dental professionals should be prepared to treat every patient as a suspected COVID-19 carrier and be ready to receive and manage an overwhelming number of patients. We suggest that dental practices establish a sensible workforce shift schedule, improve ventilation levels, reduce dental aerosol generating procedures, and develop a comprehensive guidance to Healthcare Workers to reduce the risk of COVID-19 transmission.
The aim of this study is to evaluate the eff ect of Low Intensity Pulsed Ultrasound (LIPUS) on marginal bone loss and osseointegration of dental implant using Cone Beam CT (CBCT) image analysis, torque wrench and Resonance Frequency Analysis (RFA) techniques. The study sample comprised of 22 patients; who were divided randomly into two equal groups (n=11). Each patient received one dental implant placed in the maxillary premolar region. Following fi rst stage implant surgery, in Group I, LIPUS was delivered to the implant operation site for 10 weeks before loading and for another 10 weeks post loading, while in control Group II, the implant wound was allowed to heal in the conventional way. The patients in both groups were followed up at 3 months and 6 months using clinical and radiological assessments that comprised of CBCT image analysis, Torque wrench and RFA values. The peri-implant bone height and width were measured and compared at three diff erent views (coronal, sagittal and axial) using CBCT at day 0, 3 months and 6 months. Statistical analysis using repeated measure ANOVA with signifi cance level of p<0.05 was employed for the evaluation and comparison within the same group and among the two diff erent groups based on specifi c time points. There was an increase in marginal bone level in Group I at six months post-operative and marginal bone lone loss in Group II within the same time interval. The marginal bone gain in Group I was statistically signifi cant at the buccal bone plate site. In both groups, there was an increase in torque wrench and RFA values but the increase was more signifi cant in Group I (LIPUS treated) compared to control group at six months post-operative. LIPUS promote bone healing around dental implant and can be utilized as a treatment modality to save implant with questionable stability and to enhance bone regeneration and quality osseointegration
Background Titanium dioxide dental implants have a controversial effect on reactive oxygen species (ROS) production. ROS is necessary for cellular signal transmission and proper metabolism, but also has the ability to cause cell death as well as DNA, RNA, and proteins damage by excessive oxidative stress. This study aimed to systematically review the effect of titanium dioxide dental implant-induced oxidative stress and its role on the osteogenesis-angiogenesis coupling in bone remodeling. Methods This systematic review was performed conforming to preferred reporting items for systematic review and meta-analysis (PRISMA) model. Four different databases (PubMed, Science Direct, Scopus and Medline databases) as well as manual searching were adopted. Relevant studies from January 2000 till September 2021 were retrieved. Critical Appraisal Skills Programme (CASP) was used to assess the quality of the selected studies. Results Out of 755 articles, only 14 which met the eligibility criteria were included. Six studies found that titanium dioxide nanotube (TNT) reduced oxidative stress and promoted osteoblastic activity through its effect on Wnt, mitogen-activated protein kinase (MAPK) and forkhead box protein O1 (FoxO1) signaling pathways. On the other hand, three studies confirmed that titanium dioxide nanoparticles (TiO2NPs) induce oxidative stress, reduce ostegenesis and impair antioxidant defense system as a significant negative correlation was found between decreased SIR3 protein level and increased superoxide (O2•-). Moreover, five studies proved that titanium implant alloy enhances the generation of ROS and induces cytotoxicity of osteoblast cells via its effect on NOX pathway. Conclusion TiO2NPs stimulate a wide array of oxidative stress related pathways. Scientific evidence are in favor to support the use of TiO2 nanotube-coated titanium implants to reduce oxidative stress and promote osteogenesis in bone remodeling. To validate the cellular and molecular cross talk in bone remodeling of the present review, well-controlled clinical trials with a large sample size are required.
To evaluate the ability of the maxillary sinus membrane to produce bone after internal sinus lifting and implant placement without adding exogenous bone graft, and to assess the quality of bone that has been produced 6 months postoperatively. In this retrospective study, 10 subjects who underwent maxillary sinus floor lifting and met the inclusion criteria were selected and then subdivided into: Group-A underwent internal sinus elevation and placement of implants without the use of bone graft and Group-B underwent classical internal sinus lifting and placement of bovine bone particles and then placement of the implant as a control group. Radiofrequency analysis (RFA) values for measuring the Implant Stability Quotient (ISQ) of all implants were measured by Osstell device. CBCT was performed involving linear measurements of the site of sinus lifting for both groups. High RFA values demonstrating excellent biomechanical stability were observed in Group-A compared to Group-B at 6 months postoperatively. Group-A showed a median of ISQ value;78 (8), 77(12), 79(3.5) and 77(4.50). Group-A was significantly higher in ISQ values than Group-B, which showed median and interquartile range (IQR) of ISQ value of [51(12.50), 54(14.50), 55(9), and 55(7.50)]. However, the amount of bone available in group B was significantly higher than group A; [3.5 mm (0.75) and 3.8 mm (0.69)]. Internal sinus lifting without bone graft has the ability of bone formation by osteogenic potential of the sinus membrane. Nevertheless, the high quality of bone being produced is of high importance for the success of an implant without the need for an exogenous bone graft. The newly formed bone was significantly of a better quality in Group-A. Thus, it is recommended to perform internal sinus lifting, without adding bone graft material and allow the osteogenic potential of the maxillary sinus membrane to produce its own osteogenic cells.
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