Histometric and Histological Analysis of Bone to Screw Contact Between Metallic and Absorbable 2.0 Fixation System: A Pilot Study in Dogs

ObjectiveTo evaluate the bone/screw interface of a titanium IF system and an absorbable IF system.Materials and methodsTwelve male adult dogs were subjected to osteotomy performed between the third and fourth mandibular premolars, been divided into two groups (control or experimental side). Two miniplates were applied to fix mandible fragments. Histometric values for bone-to-screw contact (BSC), bone-to-screw distance (BSD) and histological findings were evaluated at 2 and 18 weeks.ResultsDifference in BSC were detected from absorbable and metallic monocortical group on the experimental side at 2 weeks (p = 0.0041). Larger BSDs were detected at buccal bicortical absorbable experimental sides (p = 0.0041), with larger distances detected from the vestibular side to the lingual cortical side (p < 0.0001) and on the control side at 18 weeks (p = 0.0143), having metallic group significant BSD results on the experimental side at 2 weeks (p = 0.047). Connective tissue was noted on vestibular cortical side in monocortical and bicortical absorbable screw groups. ConclusionsAbsorbable bicortical screws with splint had histometric and histological behaviors similar to metallic bicortical group at lingual cortical side.Clinical RelevanceInion absorbable bicortical screws did not promote connective tissue formation at lingual cortical side.

Implant survival after graftless sinus floor augmentation in highly atrophic maxillae: a randomized controlled trial in a split mouth study

Purpose The success rate of dental implants after graftless sinus augmentation versus conventional sinus augmentation surgery in atrophic maxillae in edentulous patients was investigated. Methods This randomized study was performed in ten edentulous patients with marked maxillary atrophy. On the graftless side, the sinus membrane was lifted by a resorbable membrane. The control side was augmented with a mixture of autografts and xenografts. Implant placement followed 6 months postoperatively. Outcomes were implant survival, success of prosthetic rehabilitation and stability of vertical bone gain. Results Ten patients were included. Postoperative radiology showed sufficient bone gain on both maxillary sides. Follow-up varied from 57 to 88 months. The conventional side showed significant (p = 0.041) more bone gain than the experimental side (respectively, 9.69 mm and 6.20 mm). A total of 59 implants were placed: 30 after conventional, 29 after graftless augmentation. One implant was lost on the conventional side and four on the experimental side. The implant survival was significantly higher on the conventional side (96.7% vs. 86.2%, p < 0.001, RR = 4.14). Prosthetic restoration was functionally successful in all cases. Conclusion Bone gain and implant survival were significantly lower in the non-grafted side versus the grafted side. Prosthetic rehabilitation was possible in all ten patients. The non-grafted technique may have some potential for clinical use, although it showed poorer results. Trial registration The Netherlands Trialregister. NTR NL3541 (NTR3696). Registered 20 January 2013, https://www.trialregister.nl/trial/3541.

Effects of submucosally administered platelet-rich plasma on the rate of tooth movement:

ABSTRACT Objectives To evaluate the effects of submucosally administered platelet-rich plasma (PRP) on the rate of maxillary canine retraction. Levels of soluble receptor activator of nuclear factor-κb ligand (sRANKL) and osteoprotegerin (OPG) in the gingival crevicular fluid (GCF) were also measured over 2 months. Materials and Methods This split-mouth trial involved 20 sites in 10 subjects randomly assigned to PRP (experimental) side and control side. After alignment, the freshly prepared PRP was injected submucosally distal to the experimental side maxillary canine, and retraction was performed using NiTi closed-coil springs (150 g) on 0.019 × 0.025-inch stainless steel wire. The rate of canine movement was assessed using digital model superimposition at 0, 30, and 60 days. The OPG and sRANKL were assayed using enzyme-linked immunosorbent assay from GCF collected at 0, 1, 7, 21, 30, and 60 days. Results Twenty sites were analyzed using paired t test. The rate of tooth movement increased significantly by 35% on the PRP side compared with the control side in the first month (P = .0001) and by 14% at the end of the second month (P = .015). Using the Mann–Whitney U test, OPG levels were found to be significantly decreased on the 7th (P = .003) and 30th day on the PRP side (P = .01), while sRANKL became detectable by the third week postinjection on the PRP side (P = .069). Conclusions Submucosal injection of platelet-rich plasma significantly increased tooth movement during the 60-day observation period. Local injection of PRP significantly altered the levels of OPG and sRANKL in GCF.

Impact of background effects on the inclusive Vcb determination

The determination of the CKM element Vcb from inclusive semileptonic b → cℓ$$ \overline{\nu} $$ ν ¯ decays has reached a high precision thanks to a combination of theoretical and experimental efforts. Aiming towards even higher precision, we discuss two processes that contaminate the inclusive Vcb determination; the b → u background and the contribution of the tauonic mode: b → c(τ → μν$$ \overline{\nu} $$ ν ¯ )$$ \overline{\nu} $$ ν ¯ . Both of these contributions are dealt with at the experimental side, using Monte-Carlo methods and momentum cuts. However, these contributions can be calculated with high precision within the Heavy-Quark Expansion. In this note, we calculate the theoretical predictions for these two processes. We compare our b → u results qualitatively with generator-level Monte-Carlo data used at Belle and Belle II. Finally, we suggest to change the strategy for the extraction of Vcb by comparing the data on B → Xℓ directly with the theoretical expressions, to which our paper facilitates.

THE USE OF MICRO-OSTEOPERFORATION CONCEPT FOR ACCELERATING DIFFERENTIAL TOOTH MOVEMENT

Objective: To compare the rate of accelerated tooth movement in canine retraction with micro-osteoperforation on one side and control on the other. Study Design: Quasi experimental study. Place and Duration of Study: Orthodontics department, Armed Forces Institute of Dentistry, Rawalpindi Pakistan, from Jul 2018 to Jan 2019. Methodology: A total of 30 patients were inducted. After alignment and extraction of maxillary first premolars, canine retraction was started with closed NiTi coil spring on both sides of the maxillary arch. Micro-osteoperforation was done on the right side and other side was a control side. The distance between the lateral incisor and the canine was measured on both sides before micro-osteoperforation. The same measurements were recorded after three weeks of retraction. The difference between pre and post retraction measurements was recorded. The difference in the rate of canine retraction between both modalities was compared using independent sample t-test. Results: The study included 17 males (56%) and 13 females (43%). The mean rate of tooth movement at experimental side of maxilla was 1.6 ± 0.52 mm and on control side was 0.66 ± 0.31 mm (p<0.05). Conclusion: Micro-osteoperforation was an effective, comfortable, and safe procedure to accelerate tooth movement (1.6 times in accordance with this study). It significantly shorten the duration of orthodontic treatment.

Analgesic Efficacy of Cordia Verbenacea-based Gel in the Reduction of Pain Associated with Use of Separator Elastics/ Eficácia Analgésica do Gel à base de Cordia Verbenacea na Redução de Tinta Associada ao Uso de Elásticos Separadores

Introduction: In Orthodontics separator elastics are used to create space for inserting the bands. This causes pain. Phytotherapy has been promising as a therapy. Objective. This double blind randomized clinical trial evaluated the level of pain due to the use of elastic separator (SE) after intraoral topical administration of Cordia verbenacea gel (CV). Methods. 50 volunteers received the SE on the mesial and distal surfaces of the maxillary first molars. In a blinded manner, 0.5 g of the gel was used in one hemi-arch, and placebo in the other hemi-arch on the free gingival margin of the first molar, every 8 hours, for 3 days. Pain was measured on a visual analog scale (VAS), before insertion of the SE (t0), immediately after (t1) and every hour after the following applications. Sensory analysis of the was performed for effects of taste and burning. Wilcoxon (comparison between sides) and Friedman and Nemenyi tests were performed for comparisons between times (α=0.05). Results. The pain was lower on the side that received the phytotherapeutic gel, from the first application until before the removal of the elastic (p 0.05). As regards the burning sensation, the experimental side had higher scores and 20% of the subjects considered the CV gel had an unpleasant taste. It was concluded that the use of the intrabucal topic of CV has an analgesic potential for pain resulting from the insertion of SE.

Remarks on the Abraham–Minkowski problem, from the formal and from the experimental side

We analyze the Abraham–Minkowski problem known from classical electrodynamics from two different perspectives. First, we follow a formal approach, implying use of manifolds with curved space sections in accordance with Fermat’s principle, emphasizing that the resulting covariant and contravariant components of the photon four-momentum are a property linked to the Minkowski theory only. There is thus no link to the Abraham theory in that context. Next we turn to the experimental side, giving a brief account of older and newer radiation pressure experiments that clearly show how the Minkowski photon momentum is preferable under optical conditions. Under low-frequency conditions, where experimental detection of the individual oscillations predicted by the Abraham term are possible, the picture is however quite different.

Flexural Behavior of Reinforced Concrete Beams Covered by Gypsum Layers and Exposed to Elevated Temperatures

The paper presents results of exposure of normal concrete to elevated temperatures (400 and 700) °C covered by layers (gypsum and plaster) with different thicknesses (10 and 20) mm. The casted specimens for each type of test were divided into three groups. The first was without covering the concrete surface with gypsum, while the second and third groups were covered with gypsum of the outer surface with a thickness of 10 and 20 mm, respectively. The experimental results found that the ultimate load capacity and the first crack load of RC beams were improved by using gypsum layers through 400°C. At thickness 10 and 20 mm, the (Pcr and Pu) loss was about (8 and 6) % and (1 and 7) % respectively, compared to the concrete not covered with gypsum, the loss rate is about (25 and 13) %, and this is clear evidence of the benefit of gypsum in reducing the Elevated Temperatures directly to concrete. As for the temperature of 700, the reduction in (Pcr and Pu) was about (57 and 22) % and (31 and 16) % and (10 and 15) % at 0, 10, 20 mm gypsum thickness, respectively. Through the figures shown in the paper, which were obtained from the experimental side of the research, the load-deflection curves improved when the gypsum thickness increased during the specimens' exposure to fire. Where the relationship between them at a temperature of 400°C in a thickness of 20 mm was better than 10 mm when exposed to fire, so by increasing the thickness of the gypsum, the occurrence of deflection is less because it protects the surface of the concrete from direct exposure to heat and thus prevents the occurrence of cracks in the outer surface of the concrete.

Recent experimental enhancement techniques applied in the receiver part of the parabolic trough collector – A review

Recently, the thermal performance of the parabolic trough collector (PTC), augmented to be more applicable and efficient, received intensive research. These studies aimed to improve heat transfer in the receiver part, in order to decrease the heat loss, and enhance the heat transfer to the thermal fluid. Many previous review papers focused on the numerical sides rather than the experimental side. Several research papers recommended doing more research in the experimental field; in order to decrease the gap between the numerical and experimental results, as well as increase the confidence level of what has been done in the theoretical field researches. Regarding the recommendations of the recent papers to decrease the gap between numerical and experimental aspects, this review paper focused on the recent experimental research related to thermal enhancement performance in the receiver part of the parabolic solar collector. In this research, different categories of the enhancement methods are discussed in detail through this review, namely nanofluids, surface modifications, and inserts models or the two categories combined together. We discussed these categories for different parabolic troughs considering only the recent experimental research between the period from 2014 up to 2019. Some parameters were discussed, such as the main dimensions of the examined receiver and parabolic collector. Moreover, types of nanoparticle specifications and preparation methods with different base fluids were highlighted. In addition, we discussed different aspects of using inserts models and inlet and outlet surface modification methods. Finally, the main thermal efficiency and thermal performance enhancement results for each work were presented.