Aging resistance, mechanical properties and translucency of different yttria-stabilized zirconia ceramics for monolithic dental crown applications

OBJECTIVES

The dental market moves towards high-translucency monolithic zirconia dental crowns, which are usually placed either with - or without - a thin glaze layer. The microstructural features and the mechanical performances of these materials are still controversial, as well as their susceptibility to aging. This paper aims at studying these aspects in the current generation of zirconia dental crowns showing different degrees of translucency.

METHODS

Four different commercial zirconia materials were investigated, including one standard 'full-strength' 3Y-TZP and three grades with improved translucency. The microstructural features (phase composition and assemblage, grain size) were carefully studied, as well as mechanical properties (biaxial bending strength and indentation toughness), translucency and aging behavior (in autoclave at 134°C). Aging was conducted on crowns with and without glaze to better represent clinical uses.

RESULTS

Important differences are found in terms of microstructures among the materials in terms of cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. We show that higher cubic phase content leads to better translucency and stability in water steam, but at the expense of strength and toughness. A compromise is always inevitable between translucency and aging resistance on one side and mechanical properties on the other side.

SIGNIFICANCE

The interplay between HLA-B27 and ERAP1/ERAP2 aminopeptidases: from anti-viral protection to spondyloarthritis

The human leukocyte antigen class I gene HLA-B27 is the strongest risk factor for ankylosing spondylitis (AS), a chronic inflammatory arthritic disorder. More recently, the Endoplasmic Reticulum Aminopeptidase (ERAP) 1 and 2 genes have been identified by genome wide association studies (GWAS) as additional susceptibility factors. In the ER, these aminopeptidases trim the peptides to a length suitable to fit into the groove of the major histocompatibility complex (MHC) class I molecules. It is noteworthy that an epistatic interaction between HLA-B27 and ERAP1, but not between HLA-B27 and ERAP2, has been highlighted. However, these observations suggest a paramount centrality for the HLA-B27 peptide repertoire that determines the natural B27 immunological function, i.e. the T cell antigen presentation and, as a by-product, elicits HLA-B27 aberrant behaviours: (i) the misfolding leading to ER stress responses and autophagy and (ii) the surface expression of homodimers acting as ligands for innate immune receptors. In this context, it has been observed that the HLA-B27 carriers, besides being prone to autoimmunity, display a far better surveillance to some viral infections. This review focuses on the ambivalent role of HLA-B27 in autoimmunity and viral protection correlating its functions to the quantitative and qualitative effects of ERAP1 and ERAP2 polymorphisms on their enzymatic activity.

TNFα deficiency results in increased IL-1β in an early onset of spontaneous murine colitis

Inflammatory bowel disease (Crohn's disease (CD) and ulcerative colitis (UC)) is a multifactorial disease resulting from immune dysregulation in the gut. The underlying colitis is characterized by high levels of inflammatory cytokines, including TNFα. Biological intervention for IBD patients using anti-TNFα antibodies is often an effective therapeutic solution. However, TNFα neutralization fails to induce remission in a subgroup of IBD patients, primarily in UC patients. There is a dearth of suitable animal models representing TNFα non-responders. Here we have combined one of the best UC models currently available, namely Winnie and the TNFαKO mouse to generate a TNFα-deficient Winnie to study early onset colitis. The induced TNFα deficiency with underlying colitis does not influence general health (viability and body weight) or clinical parameters (colon weight, colon length and histological colitis) when compared with the Winnie genotype alone. The molecular characterization resulted in identification of Il1β as the major elevated cytokine during early phases of colitis. Further, in vitro functional assay using bone marrow-derived dendritic cells confirmed IL-1β as the major cytokine released in the absence of TNFα. This study has generated a successful model of colitis that remains TNFα non-responsive and has demonstrated that IL-1β expression is a major pathway for the progression of colitis in this system. These data also suggest that IL-1β can be a potential target for clinical intervention of UC patients who fail to respond to TNFα neutralization.

Clarithromycin in the Management of Chronic Rhinosinusitis: Preliminary Results of a Possible Its New Use

The aim of this study is to evaluate the efficacy and safety of prolonged therapy with low-dose clarithromycin in patients with chronic rhinosinusitis with polyps (CRSwP) after endoscopic sinus surgery (ESS). A total of 10 patients with CRSwP were identified and subjected to bilateral ESS. In post-operative patients they were treated with nasal wash with saline solution and steroid sprays (beclomethasone). During follow-up, after 30-40 days after the operation (M = 35.4 SD = +4.33), patients reported a worsening of symptoms with onset of nasal obstruction; reduction/loss of smell; headache; onset of viscous secretions and therefore all patients continued therapy with saline nasal irrigation, topical steroid therapy and started macrolide (clarithromycin 500 mg/pill: 1 pill/day for 3 days a week for 1 month). 22-item SinoNasal Outcome Test (SNOT-22) and a score to the endoscopic evaluation (endoscopic appearance score, EAS) before and after treatment were performed to evaluate efficacy of treatment. The results of the SNOT-22 and EAS showed statistically significant improvements (p < 0.05) for some parameters such as: the need to blow nose, sneezing, hyposmia, viscous mucous secretions about the SNOT-22 and reduction of secretions and edema of the nasal mucosa about the EAS. The preliminary results of our study show that the low-dose clarithromycin for a period of 1 month can improve patient complaints with CRSwP not only through the antibacterial properties but also for the immunomodulatory characteristics.

Canine fossa puncture in endoscopic sinus surgery: report of two cases

Introduction

Chronic rhinosinusitis with nasal polyposis is a common chronic disease that often affects maxillary sinus. Endoscopic sinus surgery is the most common procedure for treating the majority of maxillary sinus lesions.

Objective

To demonstrate the role of canine fossa puncture during endoscopic sinus surgery procedure in patients with severe maxillary sinus disease.

Methods

We present 2 cases where canine fossa puncture has been performed as method to obtain a complete access to the maxillary antrum.

Results

According our experience, 2 cases on 296 endoscopic sinus surgery (0.6%) where antrostomy and used of angled microdebrider were not sufficient, canine fossa puncture has been performed as an alternative method to obtain a complete access to the maxillary antrum.

Conclusion

Although the advent of endoscopic sinus surgery, our cases support the fact that actually canine fossa puncture is a minimally invasive technique useful in selected cases.

Nociceptin reduces the inflammatory immune microenvironment in a conventional murine model of airway hyperresponsiveness

BACKGROUND

Nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) are involved in airway hyperresponsiveness (AHR) and inflammation. However, the role of nociceptin at modulating the inflammatory immune microenvironment in asthma is still unclear.

OBJECTIVE

To understand the role of N/OFQ in the regulation of a Th2-like environment, we used a conventional murine model of AHR.

METHODS

Balb/c and CD1 mice were sensitized to ovalbumin (OVA) and treated with saline solution or N/OFQ, at days 0 and 7. A group of Balb/c mice were killed at 7 and 14 days from the first sensitization for the inflammatory profile evaluation while a group of Balb/c and CD1 mice were aerosol-challenged from day 21 to 23 with OVA and killed 24 h later for functional evaluations.

RESULTS

In OVA-sensitized mice, N/OFQ significantly reduced IL-4+ CD4+ T cells in lymph nodes (LN) and IL-13 in the lungs, while it induced IFN-γ increase in the lung. The efflux of dendritic cells (DCs) to the mediastinic LN and into the lung of OVA-sensitized mice was reduced in N/OFQ-treated and sensitized mice. N/OFQ reduced the expression of CD80 on DCs, indicating its ability to modulate the activation of DCs. In a less prone Th2-like environment mice strain, such as CD1 mice, N/OFQ did not modify lung resistances as observed in BALB/c mice. Finally, spectroscopic data showed the N/OFQ was able to interact onto the membrane of DCs obtained from Balb/c rather than CD1 mice, indicating its ability to modulate AHR in a Th2-like environment with a direct activity on DCs.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data confirmed the capability of N/OFQ to modulate the immune microenvironment in the lung of Th2-biased, OVA-sensitized Balb/c mice, suggesting N/OFQ-NOP axis as a novel pharmacological tool to modulate the inflammatory immune microenvironment in asthma.

Nasal packing in sphenopalatine artery bleeding: therapeutic or harmful?

The aim of this study is to present our management protocol of sphenopalatine artery bleeding, demonstrating that nasoendoscopic cautery (NC) was a more effective method than the nasal packing, in terms of shorter inpatient stay and reduced complications rate. We present ten posterior epistaxis not resolved by nasal packing. Tabotamp^® was placed in the area of sphenopalatine foramen and/or in those parts of the posterior nasal cavity, where it was suspected that bleeding origins. In two cases, the bleeding was resolved in this way, instead eight cases needed of subperiosteal cauterization of sphenopalatine artery by Dessi bipolar forceps (MicroFrance^®). 4 of these 8 patients evidenced a remarkable bleeding removing nasal packing (Hb before-nasal packing = 15 ± 0.69 versus Hb after-nasal packing = 13.3 ± 0.81; t student = 2.94; p value = 0.025). These four patients showed a deviation of the nasal septum ipsilateral to epistaxis, and according our experience, a traumatism of sphenopalatine area can be caused by Merocel^® nasal packing in this condition. During follow-up, no recurrences of nasal bleeding have been observed in such patients. Nasal packing must be considered if posterior epistaxis is severe, but always taking into account the specific anatomy of patient and in particular septal spurs that can further compromise sphenopalatine artery. In our experience, the endoscopic endonasal cauterization of the sphenopalatine branches represented a safe and effective procedure.

Influence of finish line on the marginal seal of nanohybrid composite crowns after periodontal scaling: a microleakage study

AIM

The aim of the present microleakage study was to assess the sealing ability of nanohybrid composite crowns with different finish lines exposed to simulated mechanical periodontal treatment (SMPT).

METHODS

After sample size calculation (α=0.05; β=0.20; δ=1.0; σ=0.8), sixty extracted mandibular molars were divided into four groups (N.=15): G1, 90° shoulder; G2, beveled 90° shoulder; G3, 90° shoulder and SMPT; G4, beveled 90° shoulder and SMPT. Tooth preparations were carried out by means of diamond burs and Arkansas stones. The buildup of crowns was performed with a nanohybrid composite on master casts obtained after polyether impressions and crowns were cemented with self-adhesive cement. Groups G3 and G4 were subjected to the equivalent of five years of semestral mechanical periodontal scaling with Gracey curettes (2-mm long strokes, 5 N). Samples were immersed into a methylene blue supersaturated solution for 10 minutes. Microleakage was measured by stereomicroscopic observation of multiple sections of the samples and leakage data underwent statistical analysis with non-parametric tests.

RESULTS

Marginal microleakage was 1.53±1.27% and 17.60±12.72% of the length of the adhesive interface in G1 and G2, respectively. SMPT reduced dye penetration (P<0.001) with G3 not leaking at all and G4 leaking along the 5.58±1.84% of the adhesive interface. The bevel preparation significantly worsened the marginal seal both in control and treated crowns (P<0.001).

CONCLUSION

Microleakage of nanohybrid composite crowns increased by adding a bevel to a 90° shoulder preparation and diminished after SMPT.

S1P-induced airway smooth muscle hyperresponsiveness and lung inflammation in vivo: molecular and cellular mechanisms

BACKGROUND AND PURPOSE

Sphingosine-1-phosphate (S1P) has been shown to be involved in the asthmatic disease as well in preclinical mouse experimental models of this disease. The aim of this study was to understand the mechanism(s) underlying S1P effects on the lung.

EXPERIMENTAL APPROACH

BALB/c, mast cell-deficient and Nude mice were injected with S1P (s.c.) on days 0 and 7. Functional, molecular and cellular studies were performed.

KEY RESULTS

S1P administration to BALB/c mice increased airway smooth muscle reactivity, mucus production, PGD2 , IgE, IL-4 and IL-13 release. These features were associated to a higher recruitment of mast cells to the lung. Mast cell-deficient Kit (W) (-sh/) (W) (-sh) mice injected with S1P did not display airway smooth muscle hyper-reactivity. However, lung inflammation and IgE production were still present. Treatment in vivo with the anti-CD23 antibody B3B4, which blocks IgE production, inhibited both S1P-induced airway smooth muscle reactivity in vitro and lung inflammation. S1P administration to Nude mice did not elicit airway smooth muscle hyper-reactivity and lung inflammation. Naïve (untreated) mice subjected to the adoptive transfer of CD4+ T-cells harvested from S1P-treated mice presented all the features elicited by S1P in the lung.

CONCLUSIONS AND IMPLICATIONS

S1P triggers a cascade of events that sequentially involves T-cells, IgE and mast cells reproducing several asthma-like features. This model may represent a useful tool for defining the role of S1P in the mechanism of action of currently-used drugs as well as in the development of new therapeutic approaches for asthma-like diseases.

Crucial role of androgen receptor in vascular H2S biosynthesis induced by testosterone

BACKGROUND AND PURPOSE

Hydrogen sulphide (H2S) is a gaseous mediator strongly involved in cardiovascular homeostasis, where it provokes vasodilatation. Having previously shown that H2 S contributes to testosterone-induced vasorelaxation, here we aim to uncover the mechanisms underlying this effect.

EXPERIMENTAL APPROACH

H2 S biosynthesis was evaluated in rat isolated aortic rings following androgen receptor (NR3C4) stimulation. Co-immunoprecipitation and surface plasmon resonance analysis were performed to investigate mechanisms involved in NR3C4 activation.

KEY RESULTS

Pretreatment with NR3C4 antagonist nilutamide prevented testosterone-induced increase in H2S and reduced its vasodilator effect. Androgen agonist mesterolone also increased H2S and induced vasodilatation; effects attenuated by the selective cystathionine-γ lyase (CSE) inhibitor propargylglycine. The NR3C4-multicomplex-derived heat shock protein 90 (hsp90) was also involved in this effect; its specific inhibitor geldanamycin strongly reduced testosterone-induced H2S production. Neither progesterone nor 17-β-oestradiol induced H2S release. Furthermore, we demonstrated that CSE, the main vascular H2S-synthesizing enzyme, is physically associated with the NR3C4/hsp90 complex and the generation of such a ternary system represents a key event leading to CSE activation. Finally, H2S levels in human blood collected from male healthy volunteers were higher than those in female samples.

CONCLUSIONS AND IMPLICATIONS

We demonstrated that selective activation of the NR3C4 is essential for H2S biosynthesis within vascular tissue, and this event is based on the formation of a ternary complex between cystathionine-γ lyase, NR3C4and hsp90. This novel molecular mechanism operating in the vasculature, corroborated by higher H2S levels in males, suggests that the L-cysteine/CSE/H2S pathway may be preferentially activated in males leading to gender-specific H2S biosynthesis.

Gas what: NO is not the only answer to sexual function

The ability to get and keep an erection is important to men for several reasons and the inability is known as erectile dysfunction (ED). ED has started to be accepted as an early indicator of systemic endothelial dysfunction and subsequently of cardiovascular diseases. The role of NO in endothelial relaxation and erectile function is well accepted. The discovery of NO as a small signalling gasotransmitter led to the investigation of the role of other endogenously derived gases, carbon monoxide (CO) and hydrogen sulphide (H2 S) in physiological and pathophysiological conditions. The role of NO and CO in sexual function and dysfunction has been investigated more extensively and, recently, the involvement of H2 S in erectile function has also been confirmed. In this review, we focus on the role of these three sister gasotransmitters in the physiology, pharmacology and pathophysiology of sexual function in man, specifically erectile function. We have also reviewed the role of soluble guanylyl cyclase/cGMP pathway as a common target of these gasotransmitters. Several studies have proposed alternative therapies targeting different mechanisms in addition to PDE-5 inhibition for ED treatment, since some patients do not respond to these drugs. This review highlights complementary and possible coordinated roles for these mediators and treatments targeting these gasotransmitters in erectile function/ED.