Osseointegration of layer-by-layer polyelectrolyte multilayers loaded with IGF1 and coated on titanium implant under osteoporotic condition.

PURPOSE: Titanium implant is a widely used method for dental prosthesis restoration. Nevertheless, in patients with systemic diseases, including osteoporosis, diabetes, and cancer, the success rate of the implant is greatly reduced. This study investigates a new implant material loaded with insulin-like growth factor 1 (IGF1), which could potentially improve the implant success rate, accelerate the occurrence of osseointegration, and provide a new strategy for implant treatment in osteoporotic patients. MATERIALS AND METHODS: Biofunctionalized polyelectrolyte multilayers (PEMs) with polyethylenimine as the excitation layer and gelatin/chitosan loaded with IGF1 were prepared on the surface of titanium implant by layer-by-layer self-assembly technique. The physical and chemical properties of the biofunctionalized PEMs, the biological characteristics of bone marrow mesenchymal stem cells (BMMSCs), and bone implant contact correlation test indexes were detected and analyzed in vitro and in vivo using osteoporosis rat model. RESULTS: PEMs coatings loaded with IGF1 (TNS-PEM-IGF1-100) implant promoted the early stage of BMMSCs adhesion. Under the action of body fluids, the active coating showed sustained release of growth factors, which in turn promoted the proliferation and differentiation of BMMSCs and the extracellular matrix. At 8 weeks from implant surgery, the new bone around the implants was examined using micro-CT and acid fuchsin/methylene blue staining. The new bone formation increased with time in each group, while the TNS-PEM-IGF1-100 group showed the highest thickness and continuity. CONCLUSION: TNS-PEM-IGF1-100 new implants can promote osseointegration in osteoporotic conditions both in vivo and in vitro and provide a new strategy for implant repair in osteoporotic patients.

Chronic sleep deprivation alters the myosin heavy chain isoforms in the masseter muscle in rats.

To investigate the changes in myosin heavy chain (MyHC) isoforms of rat masseter muscle fibres caused by chronic sleep deprivation and a possible link with the pathogenesis of disorders of the temporomandibular joint (TMJ). A total of 180 male rats were randomly divided into three groups (n=60 in each): cage controls, large platform controls, and chronic sleep deprivation group. Each group was further divided into three subgroups with different observation periods (7, 14, and 21 days). We investigated he expression of MyHC isoforms in masseter muscle fibres by real-time quantitative polymerase chain reaction (PCR), Western blotting, and immunohistochemical staining. In rats with chronic sleep deprivation there was increased MyHC-I expression in layers of both shallow and deep muscles at 7 and 21 days compared with the control groups, whereas sleep deprivation was associated with significantly decreased MyHC-II expression. At 21 days, there were no differences in MyHC-I or MyHC-II expression between the groups and there were no differences between the two control groups at any time point. These findings suggest that chronic sleep deprivation alters the expression of MyHC isoforms, which may contribute to the pathogenesis of disorders of the TMJ.

Should aspirin be stopped before tooth extraction? A meta-analysis.

OBJECTIVE: To carry out a standard meta-analysis to determine if aspirin should be stopped before tooth extraction. STUDY DESIGN: The PubMed, ScienceDirect, EBSCOhost, and Science Citation Index databases were searched for studies published up to September 30, 2014. Eligible studies were restricted to randomized controlled trials (RCTs) and controlled, nonrandomized trials. RESULTS: Three RCTs and seven controlled trials met the inclusion criteria (covering 1752 patients: 529 on aspirin therapy and 1223 not on aspirin therapy). The results showed that the risk of postoperative hemorrhage was significantly higher in patients on aspirin therapy (relative risk [RR] = 2.46; 95% confidence interval [CI]: 1.45-4.81) but that bleeding time (BT) was not significantly different between the two groups (standardized mean difference [SMD] = 0.63; 95% CI: -0.04 to 1.31). Sensitivity analyses showed that the results were unstable. CONCLUSIONS: We could reach a conclusion that BT is prolonged or hemorrhage is exacerbated by long-term use of aspirin. We recommend not stopping long-term aspirin use before tooth extraction but enhancing hemostasis methods, if necessary.

Influence of sleep deprivation on expression of MKK4 and c-fos in the mandibular condylar cartilage of rats.

The aim of this study was to investigate the changes in expression of mitogen-activated protein kinase kinase 4 (MKK4) and c-fos in the mandibular condylar cartilage of rats that had been subjected to sleep deprivation. One hundred and twenty female Wistar rats were randomly divided into 6 groups with 20 in each: sleep deprivation for 2 days, 4 days, 6 days, and 8 days, large-platform controls, and cage controls. After sleep deprivation by the modified multiple platform method the sleep-deprived rats were killed. The large-platform and cage control rats were killed at the same time as the rats deprived of sleep for 8 days. Haematoxylin and eosin were used to record the morphological changes in cartilage, and immunohistochemistry and real-time quantitative polymerase chain reaction (PCR) were used to detect the expression of MKK4 and c-fos. Pathological alterations were apparent after 6 and 8 days of sleep deprivation. Compared with control groups, the expression of MKK4 in the sleep-deprived groups was lower, while that of c-fos was higher. As the duration of sleep deprivation increased, the expression of MKK4 decreased. These results indicate that the variation in expression of MKK4 and c-fos may be correlated with pathological changes induced by sleep deprivation in mandibular condylar cartilage in rats.

The influence of psychological stress on the rat temporomandibular joint with the application of countermeasures.

OBJECTIVE: This study aimed to provide an experimental theoretical basis for the treatment of temporomandibular disorders by observing the effects of psychological stress and countermeasures on the rat temporomandibular joint (TMJ). METHODS: Rats were exposed to psychological stress via a communication box and the lateral pterygoid muscle and TMJ were observed with transmission electron microscopy and scanning electron microscopy. Furthermore, the expression of interleukin-1 and tumor necrosis factor-α was assessed in control animals and psychological stress (PS) and stress with diazepam (PS+DI) groups. RESULTS: Transmission electron microscopy of the lateral pterygoid muscle fibers in the PS showed vacuolar changes in the mitochondria, loss of cristae, and reduced matrix density to variable degrees after 1, 3, and 5 wk of stress. After 5 wk stress+recovery, the cristae and matrix were normal in the PS and PS+DI groups. Scanning electron microscopy of PS rats showed some synovial membranes were detached from the surface of the articular disc after 1 wk. After 3 wk, collagen fibers appeared to have wider waves and worn strips changing in size on the articular disc; after 5 wk, the distribution of collagen fibers was distorted. In PS+recovery and PS+DI rats, no obvious changes were observed on the surface of the articular disc after 1 to 5 wk stress. In PS rats, interleukin-1 and tumor necrosis factor-α expression increased significantly but was at control levels in the PS+DI and PS+recovery groups. CONCLUSION: Counteracting psychological stress can antagonize its effects on the TMJ and provide a reference for the treatment of stress-related temporomandibular disorders.

In vivo alveolar bone regeneration by bone marrow stem cells/fibrin glue composition.

The repair of alveolar bone defects caused by trauma, periodontal diseases and inflammation is still a challenge for both researchers and clinicians. Although there are many attempts to regenerate bone based on different seed cells and scaffolds, the results are still unsatisfactory. This study aims to clarify whether it could be efficient to reconstruct the alveolar bone by the combination of bone marrow stem cells (BMSCs) without pre-osteoinduction in vitro with fibrin glue (FG). The BMSCs were obtained from 2-week-old Sprague-Dawley (SD) rats and expanded in vitro with non-introduction. Afterwards, they were composited with FG for in vivo implantation. The animal models of traumatic alveolar bone defects were established bilaterally in the maxilla of 15 rats which were randomly divided into 3 groups. The BMSCs/FG composition was transplanted into 5 rats of the treated group. Another 5 rats in the negative control group were transplanted by pure FG without BMSCs. The rest 5 rats served as the blank control. Gross observation and histological analysis were made to evaluate the new bone formation 6 weeks after transplantation. Micro-CT was also used to estimate the bone healing through three-dimensional reconstruction and the bone density analysis. The amount of new bone formed in the treated group was significantly greater than the negative and blank control. Our results suggest that the strategy of combing BMSCs with FG is effective in the repair of alveolar bone defects. Its clinical application is promising.