FasL Is Required for Osseous Healing in Extraction Sockets in Mice

Fas ligand (FasL) is a member of the tumor necrosis factor (TNF) superfamily involved in the activation of apoptosis. Assuming that apoptosis is initiated after tooth extraction it is reasonable to suggest that FasL may play a pivotal role in the healing of extraction sockets. Herein, we tested the hypothesis of whether the lack of FasL impairs the healing of extraction sockets. To this end, we extracted upper right incisors of FasL knockout (KO) mice and their wildtype (WT) littermates. After a healing period of two weeks, bone volume over total volume (BV/TV) via µCT and descriptive histological analyses were performed. µCT revealed that BV/TV in the coronal region of the socket amounted to 39.4% in WT and 21.8% in KO, with a significant difference between the groups (p=0.002). Likewise, in the middle region of the socket, BV/TV amounted to 50.3% in WT and 40.8% in KO (p<0.001). In the apical part, however, no difference was noticed. Consistently, WT mice displayed a significantly higher median trabecular thickness and a lower trabecular separation when compared to the KO group at the coronal and central region of the socket. There was the overall tendency that in both, female and male mice, FasL affects bone regeneration. Taken together, these findings suggest that FasL deficiency may reduce bone regeneration during the healing process of extraction sockets.

Successive occurrences of quasi-circular ribbon flares in a fan-spine-like configuration involving hyperbolic flux tube

We present a comprehensive analysis of the formation and evolution of a fan-spine-like configuration that developed over a complex photospheric configuration where dispersed negative polarity regions were surrounded by positive polarity regions. This unique photospheric configuration, analogous to the geological “atoll” shape, hosted four homologous flares within its boundary. Computation of the degree of squashing factor (Q) maps clearly revealed an elongated region of high Q-values between the inner and outer spine-like lines, implying the presence of an hyperbolic flux tube (HFT). The coronal region associated with the photospheric atoll configuration was distinctly identified in the form of a diffused dome-shaped bright structure directly observed in EUV images. A filament channel resided near the boundary of the atoll region. The activation and eruption of flux ropes from the filament channel led to the onset of four eruptive homologous quasi-circular ribbon flares within an interval of ≈11 hours. During the interval of the four flares, we observed continuous decay and cancellation of negative polarity flux within the atoll region. Accordingly, the apparent length of the HFT gradually reduced to a null-point-like configuration before the fourth flare. Prior to each flare, we observed localised brightening beneath the filaments which, together with flux cancellation, provided support for the tether-cutting model of solar eruption. The analysis of magnetic decay index revealed favourable conditions for the eruption, once the pre-activated flux ropes attained the critical heights for torus instability.

Using two “V” shaped flaps in penile torsion treatment

Introduction: Penile torsion is a congenital malformation that causes a rotational deformity of the penile shaft. Several techniques have been considered for penile torsion repair. In this study, we described our experience using two separate “V” dartos flaps, which leads to a more satisfying result. Patient and methods: Two young men with severe penile torsion aged 24 and 28 years old were candidates for surgery. During our novel method for penile torsion repair, we degloved the penis and dissected the dartos fascia from the penis shaft, then cut it distally from the sub-coronal region with a longitudinal cut to make two dartos flaps in a “V” shape. With these two flaps, we corrected penile torsion in a more satisfying way without crossing the urethra. Results: Penile torsion and concurrent chordee were completely corrected after surgery. Urine culture was sterile and uroflowmetry indicated a maximal urinary flow of 12 ml/s 3 months after the operation. Both patients were satisfied with ejaculation and their follow-up indicated complete resolution of penile torsion. Conclusions: Penile torsion is a challenging congenital anomaly. We used a two “V” shaped flap passage method to complete penile rotation and chordee correction without performing any plication techniques. Our penile torsion correction procedure resulted in the successful repair of torsion and excellent outcomes. Level of evidence: Not applicable for this multicenter audit.

Analysis of Linear and Angular Deviations of Implants Installed With a Tomographic-Guided Surgery Technique: A Prospective Cohort Study

The aim of this study was to evaluate the linear and angular deviations of the implants installed by the computerized tomography (CT)–guided surgery technique. Eighteen patients who underwent implant insertion by means of CT-guided surgery participated in this study. Ten of these patients had a fully edentulous maxilla, and 8 had a fully edentulous mandible. The patients received a total of 115 implants, of which 81 implants were installed in the maxilla and 34 installed in the mandible. Tomographic guides were made for tomographic examination in both the upper and lower jaws. After the image acquisition, the virtual planning of the positioning of the implants was performed in relation to the previously made prosthesis. The measurement of the linear and angular deviations between the virtual planning and the final position of the implants was performed with the overlap of the planning and postoperative tomography. There were no differences in the linear and angular deviations of the implants installed in the maxilla and mandible. Compared with the coronal region, there was a trend of greater linear deviations in the apical regions of the implants and a greater tendency toward deviations in the posterior regions than in the anterior regions of both arches. The CT-guided surgery promoted the installation of implants with high accuracy and allowed the installation of straight pillars in all cases evaluated. The linear deviations were not different in the different regions of the mouth or in the different portions of the implants.

Altered bone growth dynamics prefigure craniosynostosis in a zebrafish model of Saethre-Chotzen syndrome

Cranial sutures separate the skull bones and house stem cells for bone growth and repair. In Saethre-Chotzen syndrome, mutations in TCF12 or TWIST1 ablate a specific suture, the coronal. This suture forms at a neural-crest/mesoderm interface in mammals and a mesoderm/mesoderm interface in zebrafish. Despite this difference, we show that combinatorial loss of TCF12 and TWIST1 homologs in zebrafish also results in specific loss of the coronal suture. Sequential bone staining reveals an initial, directional acceleration of bone production in the mutant skull, with subsequent localized stalling of bone growth prefiguring coronal suture loss. Mouse genetics further reveal requirements for Twist1 and Tcf12 in both the frontal and parietal bones for suture patency, and to maintain putative progenitors in the coronal region. These findings reveal conservation of coronal suture formation despite evolutionary shifts in embryonic origins, and suggest that the coronal suture might be especially susceptible to imbalances in progenitor maintenance and osteoblast differentiation.

Statistical study of magnetic reconnection in accretion disks systems around HMXBs

Highly magnetized accretion disks are present in high-mass X-ray binaries (HMXBs). A potential mechanism to explain the transition between the High/Soft and Low/Hard states observed in HMXBs can be attributed to fast magnetic reconnection induced in the turbulent corona. In this work, we present results of global general relativistic MHD (GRMHD) simulations of accretion disks around black holes that show that fast reconnection events can naturally arise in the coronal region of these systems in presence of turbulence triggered by MHD instabilities, indicating that such events can be a potential mechanism to explain the transient non-thermal emission in HMXBs. To find the zones of fast reconnection, we have employed an algorithm to identify the presence of current sheets in the turbulent regions and computed statistically the magnetic reconnection rates in these locations obtaining average reconnection rates consistent with the predictions of the theory of turbulence-induced fast reconnection.

Effects of Silane on the Push-out Bond Strength of Fiber-reinforced Resin Posts luted with different Self-adhesive Resin Cements

ABSTRACT Aim The present study was completed to evaluate the effect of silane on the push-out bond strength on fiber-reinforced posts. The intention of the study was also to determine if there was a regional relation between the adhesive system and the push-out bond strength of the fiber post. Materials and methods Fifteen single rooted human teeth were endodontically treated and 2 mm diameter glass fiber-reinforced composite posts were cemented in the root canal. In the first group Futurabond DC without silane, in the second group the same luting material after silane treatment of the posts, and in the third group Clearfil DC Core System without silane were used to lute the posts. After complete setting of the luting agents three 2-mm-thick slices were obtained from the cervical, middle, and apical regions of the roots. The specimens were subjected to push-out test in special equipment. Bond strength data were analyzed with analysis of variance tests. Results The Rebilda posts cemented with Futurabond DC without silane had the highest push-out bond strength at the coronal region (164.71 N ± 72.12), while the posts cemented with Clearfil without silane had the lowest value at the apical region (94.86 N ± 34.14). Silane had no significance on the push-out bond strength (p = 0.909); however, the root canal dentin regions had a significant effect (p < 0.010). Conclusion This study did not show any significant differences among different luting protocols. The bond strength was significantly higher in the coronal region due to the greater cemented surface area and the difference in dentin structure. Clinical significance Based on the results of the push-out tests, the retention of the posts did not depend on the luting methods; however, the region of the root canal played a significant role. How to cite this article Rajnics Z, Marada G, Moetaz E, Radnai M. Effects of Silane on the Push-out Bond Strength of Fiber-reinforced Resin Posts luted with different Self-adhesive Resin Cements. Int J Experiment Dent Sci 2017;6(1):22-25.

Bone Morphometric Evaluation around Immediately Placed Implants Covered with Porcine-Derived Pericardium Membrane: An Experimental Study in Dogs

Objective. To investigate whether porcine-derived bioresorbable pericardium membrane coverage enhances the osseointegration around implants placed in fresh extraction sockets.Study Design. Twenty-four commercially available endosseous implants were placed in the fresh extraction sockets of the mandibular first molar of mature beagles (n=6). On one side, implants and osteotomy sites were covered with porcine-derived bioresorbable pericardium membranes, whereas on the other side, no membranes were used. After 6 weeks, samples were retrieved and were histologically processed for histomorphometric analysis.Results. The histological observation showed that bone loss and soft tissue migration in the coronal region of the implant were evident for the control group, whereas bone fill was evident up to the neck of the implant for the membrane-covered group. Bone-to-implant contact was significantly higher for the membrane-covered group compared to the control group, 75% and 45% (P<0.02), respectively.Conclusion. The experimental membranes proved to regenerate bone around implants placed in fresh extraction sockets without soft tissue intrusion.