Stress-based performance evaluation of osseointegrated dental implants by finite-element simulation

In this paper biomechanical interaction between osseointegrated dental implants and bone is numerically investigated through 3D linearly elastic finite-element analyses, when static functional loads occur. Influence of some mechanical and geometrical parameters on bone stress distribution is highlighted and risk indicators relevant to critical overloading of bone are introduced. Insertions both in mandibular and maxillary molar segments are analyzed, taking into account different crestal bone loss configurations. Stress-based performances of five commercially-available dental implants are evaluated, demonstrating as the optimal choice of an endosseous implant is strongly affected by a number of shape parameters as well as by anatomy and mechanical properties of the site of placement. Moreover, effectiveness of some double-implant devices is addressed. The first one is relevant to a partially edentulous arch restoration, whereas other applications regard single-tooth restorations based on non-conventional endosteal mini-implants. Starting from computer tomography images and real devices, numerical models have been generated through a parametric algorithm based on a fully 3D approach. Furthermore, effectiveness and accuracy of finite-element simulations have been validated by means of a detailed convergence analysis

Polymerization shrinkage and spherical glass mega fillers: Effects on cuspal deflection

Purpose. The Authors analyzed the effect of spherical glass mega fillers (SGMF) on reducing contraction stress in dental composite resins, by means of a cavity model simulating the cuspal deflection which occurs on filled tooth cavity walls in clinical condition. Materials and methods. 20 stylized MOD cavities (C-factor = 0.83) were performed in acrylic resin. The inner surface of each cavity was sand blasted and adhesively treated in order to ensure a valid bond with the composite resin. Three different diameter of SGMF were used (i.e. 1, 1,5, 2 mm). The samples were divided in 4 groups of 5 each: Group 1 samples filled with the composite only; Group 2 samples filled with composite added with SGMFs, Ø1mm (16 spheres for each sample); Group 3 samples filled with composite added with SGMFs, Ø1,5 mm (5 spheres for each sample); Group 4 samples filled with composite added with SGMFs, Ø2 mm (2 spheres for each sample). Digital pictures were taken, in standardized settings, before and immediately after the polymerization of the composite material, placed into the cavities. With a digital image analysis software the distances from the coronal reference points of the cavity walls were measured. Then the difference between the first and second measurement was calculated. The data were analyzed by means of the ANOVA test. Results. A significative reduction on cavity walls deflection, when the composite resin is used in addiction with the SGMFs was observed. The SGMFs of smallest diameter (1mm) showed the better outcome. Conclusion. The SGMFs are reliable in reducing contraction stress in dental composite resins

Fixture-abutment connection surface and micro-gap measurements by 3D micro-tomographic technique analysis

X-ray micro-tomography (micro-CT) is a miniaturized form of conventional computed axial tomography (CAT) able to investigate small radio-opaque objects at a-few-microns high resolution, in a non-destructive, non-invasive, and tri-dimensional way. Compared to traditional optical and electron microscopy techniques, which provide two-dimensional images, this innovative investigation technology enables a sample tri-dimensional analysis without cutting, coating or exposing the object to any particular chemical treatment. X-ray micro-tomography matches ideal 3D microscopy features: the possibility of investigating an object in natural conditions and without any preparation or alteration; non-invasive, non-destructive, and sufficiently magnified 3D reconstruction; reliable measurement of numeric data of the internal structure (morphology, structure and ultra-structure). Hence, this technique has multi-fold applications in a wide range of fields, not only in medical and odontostomatologic areas, but also in biomedical engineering, materials science, biology, electronics, geology, archaeology, oil industry, and semi-conductors industry. This study shows possible applications of micro-CT in dental implantology to analyze 3D micro-features of dental implant to abutment interface. Indeed, implant-abutment misfit is known to increase mechanical stress on connection structures and surrounding bone tissue. This condition may cause not only screw preload loss or screw fracture, but also biological issues in peri-implant tissues

Prevalence of Enterococci and Vancomycin Resistance in the Throat of Non-Hospitalized Individuals Randomly Selected in Central Italy

Enterococci are commonly found in the environment and humans as a part of the normal microbiota. Among these, Enterococcus faecalis and Enterococcus faecium can convert into opportunistic pathogens, making them a major cause of nosocomial infections. The rapid diffusion of vancomycin-resistant strains and their impact on nosocomial settings is of considerable concern. Approximately one-third of the E. faecium infections in Italy are caused by vancomycin-resistant strains. This study explored the hypothesis that the oral cavity could represent a silent reservoir of virulent enterococci. A sample of 862 oral flora specimens collected from healthy human volunteers in Central Italy was investigated by real-time PCR to detect E. faecalis and E. faecium, as well as the genetic elements that most frequently determine vancomycin resistance. The prevalence of E. faecalis was 19%, a value that was not associated with alcohol consumption, tobacco smoking, or age of the subjects. Less frequently detected, with an overall prevalence of 0.7%, E. faecium was more common among people older than 49 years of age. The genes conferring vancomycin resistance were detected in only one sample. The results indicate that the oral cavity can be considered a reservoir of clinically relevant enterococci; however, our data suggest that healthy individuals rarely carry vancomycin-resistant strains

Airway stenting in a child with spondyloepiphyseal dysplasia congenita: 13-Year survival.

We describe the case of a boy with spondyloepiphyseal dysplasia congenita. At birth, he experienced severe respiratory distress necessitating tracheotomy. Endoscopy done because mechanical ventilation failed to resolve desaturations disclosed severe tracheo-bronchomalacia. A Polyflex silicone stent was placed in the trachea (replaced by Y-Dumon stent) and 2 Palmaz metallic stents in the mainstem bronchi (overlapped with 2 Jomed stents 5 years later). Airway stenting guaranteed a suitable respiratory status and allowed a child who was expected to die at birth, to reach 13.5 years old in good conditions

Degradation of 2,4,6-trichlorophenol by a specialized organism and by indigenous soil microflora: bioaugmentation and self-remediability for soil restoration

A selected mixed culture and a strain of Alcaligenes eutrophus TCP were able to totally degrade 2,4,6-TCP with stoichiometric release of Cl-. In cultures of Alc. eutrophus TCP, a dioxygenated dichlorinated metabolite was detected after 48 h of incubation. Experiments conducted with soil microcosms gave evidence that: the degradative process had a biotic nature and was accompanied by microbial growth; the soil used presented an intrinsic degradative capacity versus 2,4,6-TCP; the specialized organism used as inoculum was effective in degrading 2,4,6-TCP in a short time. These results could be utilized for the adoption of appropriate remediation techniques for contaminated soil

Topical administration of hyaluronic acid in children with recurrent or chronic middle ear inflammations

Hyaluronic acid (HA) treatment has been successfully performed in patients with recurrent upper airway infections or rhinitis. The aim of this study was to assess the efficacy and safety of the topical nasal administration of an HA-based compound by investigating its effects in children with recurrent or chronic middle ear inflammations and chronic adenoiditis. A prospective, single-blind, 1:1 randomised controlled study was performed to compare otoscopy, tympanometry and pure-tone audiometry in children which received the daily topical administration of normal 0.9% sodium chloride saline solution (control group) or 9 mg of sodium hyaluronate in 3 mL of a 0.9% sodium saline solution. The final analysis was based on 116 children (49.1% boys; mean age, 62.9 \ub1 17.9 months): 58 in the control group and 58 in the study group. At the end of follow-up, the prevalence of patients with impaired otoscopy was significantly lower in the study group (P value = 0.024) compared to baseline but not in the control group. In comparison with baseline, the prevalence of patients with impaired tympanometry at the end of the follow-up period was significantly lower in the study group (P value = 0.047) but not in the control group. The reduction in the prevalence of patients with conductive hearing loss (CHL) (P value = 0.008) and those with moderate CHL (P value = 0.048) was significant in the study group, but not in the control group. The mean auditory threshold had also significantly improved by the end of treatment in the study group (P value = 0.004) but not in the control group. Our findings confirm the safety of intermittent treatment with a topical nasal sodium hyaluronate solution and are the first to document its beneficial effect on clinical and audiological outcomes in children with recurrent or chronic middle ear inflammations associated with chronic adenoiditis

Detection of poliovirus-infected macrophages in thymus of patients with myasthenia gravis

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The alpha-synuclein RT-QuIC products generated by the olfactory mucosa of patients with parkinson’s disease and multiple system atrophy induce inflammatory responses in SH-SY5Y cells

Parkinson’s disease (PD) and multiple system atrophy (MSA) are caused by two distinct strains of disease-associated α-synuclein (αSynD). Recently, we have shown that olfactory mucosa (OM) samples of patients with PD and MSA can seed the aggregation of recombinant α-synuclein by means of Real-Time Quaking-Induced Conversion (αSyn_RT-QuIC). Remarkably, the biochemical and morphological properties of the final α-synuclein aggregates significantly differed between PD and MSA seeded samples. Here, these aggregates were given to neuron-like differentiated SH-SY5Y cells and distinct inflammatory responses were observed. To deepen whether the morphological features of α-synuclein aggregates were responsible for this variable SH-SY5Y inflammatory response, we generated three biochemically and morphologically distinct α-synuclein aggregates starting from recombinant α-synuclein that were used to seed αSyn_RT-QuIC reaction; the final reaction products were used to stimulate SH-SY5Y cells. Our study showed that, in contrast to OM samples of PD and MSA patients, the artificial aggregates did not transfer their distinctive features to the αSyn_RT-QuIC products and the latter induced analogous inflammatory responses in cells. Thus, the natural composition of the αSynD strains but also other specific factors in OM tissue can substantially modulate the biochemical, morphological and inflammatory features of the αSyn_RT-QuIC products

The risk stratification of adverse neonatal outcomes in women with gestational diabetes (STRONG) study

Aims: To assess the risk of adverse neonatal outcomes in women with gestational diabetes (GDM) by identifying subgroups of women at higher risk to recognize the characteristics most associated with an excess of risk. Methods: Observational, retrospective, multicenter study involving consecutive women with GDM. To identify distinct and homogeneous subgroups of women at a higher risk, the RECursive Partitioning and AMalgamation (RECPAM) method was used. Overall, 2736 pregnancies complicated by GDM were analyzed. The main outcome measure was the occurrence of adverse neonatal outcomes in pregnancies complicated by GDM. Results: Among study participants (median age 36.8 years, pre-gestational BMI 24.8 kg/m2), six miscarriages, one neonatal death, but no maternal death was recorded. The occurrence of the cumulative adverse outcome (OR 2.48, 95% CI 1.59–3.87), large for gestational age (OR 3.99, 95% CI 2.40–6.63), fetal malformation (OR 2.66, 95% CI 1.00–7.18), and respiratory distress (OR 4.33, 95% CI 1.33–14.12) was associated with previous macrosomia. Large for gestational age was also associated with obesity (OR 1.46, 95% CI 1.00–2.15). Small for gestational age was associated with first trimester glucose levels (OR 1.96, 95% CI 1.04–3.69). Neonatal hypoglycemia was associated with overweight (OR 1.52, 95% CI 1.02–2.27) and obesity (OR 1.62, 95% CI 1.04–2.51). The RECPAM analysis identified high-risk subgroups mainly characterized by high pre-pregnancy BMI (OR 1.68, 95% CI 1.21–2.33 for obese; OR 1.38 95% CI 1.03–1.87 for overweight). Conclusions: A deep investigation on the factors associated with adverse neonatal outcomes requires a risk stratification. In particular, great attention must be paid to the prevention and treatment of obesity