Nonlinear dynamics of a dispersive anisotropic Kuramoto–Sivashinsky equation in two space dimensions

A Kuramoto–Sivashinsky equation in two space dimensions arising in thin film flows is considered on doubly periodic domains. In the absence of dispersive effects, this anisotropic equation admits chaotic solutions for sufficiently large length scales with fully two-dimensional profiles; the one-dimensional dynamics observed for thin domains are structurally unstable as the transverse length increases. We find that, independent of the domain size, the characteristic length scale of the profiles in the streamwise direction is about 10 space units, with that in the transverse direction being approximately three times larger. Numerical computations in the chaotic regime provide an estimate for the radius of the absorbing ball in ℒ2 in terms of the length scales, from which we conclude that the system possesses a finite energy density. We show the property of equipartition of energy among the low Fourier modes, and report the disappearance of the inertial range when solution profiles are two-dimensional. Consideration of the high-frequency modes allows us to compute an estimate for the analytic extensibility of solutions in ℂ2. We also examine the addition of a physically derived third-order dispersion to the problem; this has a destabilizing effect, in the sense of reducing analyticity and increasing amplitude of solutions. However, sufficiently large dispersion may regularize the spatio-temporal chaos to travelling waves. We focus on dispersion where chaotic dynamics persist, and study its effect on the interfacial structures, absorbing ball and properties of the power spectrum

Effect of four premolar extractions on the vertical dimension of the face : A retrospective cephalometric study

PURPOSE Adequate control of the vertical dimension is of great importance in orthodontic treatment. Although existing evidence is very limited, extraction of four premolars is thought to contribute towards improved control of anterior facial height compared with non-extraction treatment protocols. Thus, the aim of this retrospective cohort study was to compare the effect of fixed-appliance treatment with extraction of four premolars to non-extraction treatment on the skeletal vertical dimension. METHODS A consecutive sample of 76 children with skeletal hyperdivergence (49% male; mean age 11.9 years) was divided into two groups for treatment with either non-extraction (n = 31) or extraction of four premolars (n = 45). Baseline characteristics were comparable: overjet 5.1 ± 2.5 mm, overbite 2.4 ± 1.9 mm, ANB angle 4.6 ± 2.3°, and SN-ML angle 40.2 ± 3.5°. Patients were treated with standard edgewise fixed appliances with closing loops/sliding mechanics. Vertical skeletal and dental outcomes were measured on lateral cephalograms before and after treatment. Data were analyzed with linear regression at 5%. RESULTS Compared to non-extraction treatment, treatment with premolar extractions had no significant effect on the SN-ML angle (difference (Δ) = 0.07°; 95% confidence interval -0.90 to 1.01°; P = 0.88). Statistically significant changes between the extraction and non-extraction groups were only found for the parameters SNA (Δ -1.47°; P = 0.003), ANB (Δ -1.17°; P = 0.004), SN-OP (Δ -1.48°; P = 0.04), and L1-ML (Δ -6.39°; P < 0.001). CONCLUSION Orthodontic treatment of children with skeletal hyperdivergence using systematic extraction of four premolars had minimal effects on the vertical facial dimension compared to non-extraction treatment

Treatment outcome with orthodontic aligners and fixed appliances: a systematic review with meta-analyses

Background: The use of orthodontic aligners to treat a variety of malocclusions has seen considerable increase in the last years, yet evidence about their efficacy and adverse effects relative to conventional fixed orthodontic appliances remains unclear. Objective: This systematic review assesses the efficacy of aligners and fixed appliances for comprehensive orthodontic treatment. Search methods: Eight databases were searched without limitations in April 2019. Selection criteria: Randomized or matched non-randomized studies. Data collection and analysis: Study selection, data extraction, and risk of bias assessment was done independently in triplicate. Random-effects meta-analyses of mean differences (MDs) or relative risks (RRs) with their 95% confidence intervals (CIs) were conducted, followed by sensitivity analyses, and the GRADE analysis of the evidence quality.Results: A total of 11 studies (4 randomized/7 non-randomized) were included comparing aligners with braces (887 patients; mean age 28.0 years; 33% male). Moderate quality evidence indicated that treatment with orthodontic aligners is associated with worse occlusal outcome with the American Board of Orthodontics Objective Grading System (3 studies; MD = 9.9; 95% CI = 3.6-16.2) and more patients with unacceptable results (3 studies; RR = 1.6; 95% CI = 1.2-2.0). No significant differences were seen for treatment duration. The main limitations of existing evidence pertained to risk of bias, inconsistency, and imprecision of included studies. Conclusions: Orthodontic treatment with aligners is associated with worse treatment outcome compared to fixed appliances in adult patients. Current evidence does not support the clinical use of aligners as a treatment modality that is equally effective to the gold standard of braces

Cytotoxicity and estrogenicity of a novel 3-dimensional printed orthodontic aligner

INTRODUCTION Orthodontic aligners printed with in-office 3-dimensional (3D) procedures have been described, but no data on their biocompatibility exist. This study investigates the cytotoxicity and estrogenicity of a 3D-printed orthodontic aligner by assessing its biological and behavioral effects. METHODS Ten sets of 1 type of aligner were immersed in sterile deionized water for 14 days, and the cytotoxicity and estrogenicity of released factors were assessed via MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays on human gingival fibroblasts and the estrogen-sensitive MCF-7 and the estrogen-insensitive MDA-MB-231 breast cancer cell lines. 17β-Estradiol and bisphenol-A were used as positive controls. The statistical analysis of data was performed with generalized linear models at a 0.05 level of significance. RESULTS No signs of cytotoxicity were seen for the aligner samples for concentrations (v/v) of 20% (P = 0.32), 10% (P = 0.79), or 5% (P = 0.76). The antioxidant activity expressed as the capacity to reduce intracellular levels of reactive oxygen species was not affected in the aligner samples (P = 0.08). No significant estrogenicity was induced by the aligner samples compared with eluents from the negative control for both MCF-7 (P = 0.65) and MDA-MB-231 (P = 0.78). As expected, 17β-Estradiol and bisphenol-A stimulated MCF-7 cell proliferation, whereas no effect was observed on MDA-MB-231 cells. CONCLUSIONS In conclusion, if any factors were released during the 14-day aging of 3D-printed aligners in water, these were not found to be cytotoxic for human gingival fibroblasts and did not affect their intracellular reactive oxygen species levels. Moreover, no estrogenic effects of these putative eluates were observed based on an E-screen assay

Prevention of orthodontic enamel demineralization: a systematic review with meta‐analyses

Aim of this systematic review was to assess the efficacy of preventive interventions against the development of white spot lesions (WSLs) during fixed appliance orthodontic treatment. Nine databases were searched without limitations in September 2018 for randomized trials. Study selection, data extraction and risk of bias assessment were done independently in duplicate. Random-effects meta-analyses of mean differences (MDs) or relative risks (RRs) with their 95% confidence intervals (CIs) were conducted, followed by sensitivity analyses, and the GRADE analysis of the evidence quality. A total of 24 papers (23 trials) were included, assessing preventive measures applied either around orthodontic brackets (21 trials; 1427 patients; mean age 14.4 years) or molar bands (2 trials; 46 patients; age/sex not reported). Active patient reminders were associated with reduced WSL incidence on patient level compared to no reminder (3 trials; 190 patients; RR: 0.4; 95% CI: 0.31-0.64; Number Needed to Treat [NNT]: 3 patients), flat surface sealants were associated with reduced WSL incidence on tooth level than no sealant (5 trials; 2784 teeth; RR: 0.8; 95% CI: 0.63-0.95; NNT: 33 teeth), and fluoride varnish was associated with reduced WSL severity on tooth level (2 trials; 1160 teeth; MD: -0.32 points; 95% CI: -0.44 to -0.21 points). However, the quality of evidence was low according to GRADE, due to risk of bias. Some evidence indicates that active patient reminders and flat surface sealants or fluoride varnish around orthodontic brackets might be associated with reduced WSL burden, but further research is needed. Keywords: adverse effects; clinical trials; dental caries; evidence-based medicine; fixed appliances; systematic review

Extracellular SPARC increases cardiomyocyte contraction during health and disease

Secreted protein acidic and rich in cysteine (SPARC) is a non-structural extracellular matrix protein that regulates interactions between the matrix and neighboring cells. In the cardiovascular system, it is expressed by cardiac fibroblasts, endothelial cells, and at lower levels by ventricular cardiomyocytes. SPARC expression levels are increased upon myocardial injury and also during hypertrophy and fibrosis. We have previously shown that SPARC improves cardiac function after myocardial infarction by regulating post-synthetic procollagen processing, however whether SPARC directly affects cardiomyocyte contraction is still unknown. In this study we demonstrate a novel inotropic function for extracellular SPARC in the healthy heart as well as in the diseased state after myocarditis-induced cardiac dysfunction. We demonstrate SPARC presence on the cardiomyocyte membrane where it is co-localized with the integrin-beta1 and the integrin-linked kinase. Moreover, extracellular SPARC directly increases cardiomyocyte cell shortening ex vivo and cardiac function in vivo, both in healthy myocardium and during coxsackie virus-induced cardiac dysfunction. In conclusion, we demonstrate a novel inotropic function for SPARC in the heart, with a potential therapeutic application when myocyte contractile function is diminished such as that caused by a myocarditis-related cardiac injury