Friction of conventional and self-ligating brackets using a 10 bracket model

The friction generated by various bracket-archwire combinations previously has been studied using in vitro testing models that included only one or three brackets. This study was performed using a specially designed apparatus that included 10 aligned brackets to compare the frictional resistance generated by conventional stainless steel brackets, self-ligating Damon SL II brackets and Time Plus brackets coupled with stainless steel, nickel-titanium and beta-titanium archwires. All brackets had a 0.022-inch slot, and five different sizes of orthodontic wire alloys used. Each bracket-archwire combination was tested 10 times, and each test was performed with a new bracket-wire sample. Time Plus self-ligating brackets generated significantly lower friction than both the Damon SL II self-ligating brackets and Victory brackets. However, the analysis of the various bracket-archwire combinations showed that Damon SL II brackets generated significantly lower friction than the other brackets when tested with round wires and significantly higher friction than Time Plus when tested with rectangular archwires. Beta-titanium archwires generated higher frictional resistances than the other archwires. All brackets showed higher frictional forces as the wire size increased. These findings suggest that the use of an in vitro testing model that includes 10 brackets can give additional interesting information about the frictional force of the various bracket-archwires combinations to the clinician and the research worker.     

Collagen fiber orientation near a fractured dental implant after a 5-year loading period: case report

PURPOSE: Fracture of an implant is one of the possible complications of dental implants. It is a quite rare event but of high clinical relevance. Nevertheless, it represents an important opportunity for evaluating the peri-implant bone-tissue response to implant overloading in human beings. The aim of the present study was a scanning electron microscopy evaluation of a screw-shaped implant retrieved because of fracture and a birefringence analysis of the tissue near the fractured implant. MATERIALS AND METHODS: There was 1 fractured screw-shaped implant retrieved from a patient with a trephine bur, and it was processed for histology. The specimen was analyzed under both scanning electron microscopy and circularly polarized light microscopy. RESULTS: The scanning electron microscopy fractography analysis showed the typical signs of a fatigue-fracture, with large plastic deformations on the implant. The fracture seemed to start from the internal coil of the implant. Under circularly polarized light microscopy investigation, a bone-implant contact percentage of 81.6% +/- 1.5% (mean +/- standard deviation) was found. The amount of the transverse collagen fibers was of 68.3%, and the amount of the longitudinal collagen fibers was of 31.7%. The difference was statistically significant for z = 2.247 (P = 0.025). CONCLUSION: The fracture of the implant was most probably correlated to a fatigue of the material mainly associated to a lesion of the internal coil. The high level of bone-implant contact percentage was correlated to a predominant transverse collagen fiber orientation of the collagen fibers in the peri-implant bone.     

Adherence of investment to Au–Pd–Ag alloy using a vacuum–argon pressure casting machine

OBJECTIVE: The removal of adhered investment material from marginal metal surfaces represents a possible risk of poor marginal adaptation.The aim of this work was to evaluate the effects of argon on investment adherence to the casting surface and on the alloy surface microstructure. METHODS: A die of stainless steel was used. 10 wax copings were cast by vacuum-argon pressure, while 10 copings by vacuum-air pressure using a Combilabor CLG-77 A in a graphite crucible; supply was direct with curved sprues of slashed circle 3.5 mm. The alloy used was Herabond. After coarse investment, removal of all specimens were investigated with scanning electron microscopy and semi-quantitative digital densitometry. RESULTS: The specimens cast under vacuum-argon pressure showed less amount of investment adhered (unpaired t test of grouped specimens, difference 2.896x10(5)pixel; p=0.002) while the grain size on the casting surface increased significantly p=0.000 (difference 5.968(microm). SIGNIFICANCE: Vacuum-argon pressure supply during casting reduces the investment adherence to the metal surface, and increases the packing density and size of the grains, especially on the casting surface. These minimize the risk of marginal distortions due to casting cleaning procedures and facilitate the finishing and polishing procedures.     

Timothy Grass Pollen Induces Spatial Reorganisation of F-Actin and Loss of Junctional Integrity in Respiratory Cells

Inflammation - Grass pollens have been identified as mediators of respiratory distress, capable of exacerbating respiratory diseases including epidemic thunderstorm asthma (ETSA). It is...     

A Rifapentine-Containing Inhaled Triple Antibiotic Formulation for Rapid Treatment of Tubercular Infection

Purpose

The potential for rifapentine-containing oral therapeutic regimens to significantly shorten the current six-month anti-tubercular treatment regimen is confounded by high plasma protein binding of rifapentine. Inhaled aerosol delivery of rifapentine, a more potent anti-tubercular antibiotic drug, in combination with other first-line antibiotics may overcome this limitation to deliver a high drug dose at the pulmonary site of infection.

Methods

A formulation consisting of rifapentine, moxifloxacin and pyrazinamide, with and without leucine, was prepared by spray-drying. This formulation was assessed for its physico-chemical properties, in vitro aerosol performance and antimicrobial activity.

Results

The antibiotic powders, with and without leucine, had similar median aerodynamic diameters of 2.58?±?0.08 μm and 2.51?±?0.06 μm, with a relatively high fine particle fraction of 55.5?±?1.9% and 63.6?±?2.0%, respectively. Although the powders were mostly amorphous, some crystalline peaks associated with the δ polymorph for the spray-dried crystalline pyrazinamide were identified.

Conclusions

Stabilisation of the powder with 10% w/w leucine and protection from moisture ingress was found to be necessary to prevent overt crystallisation of pyrazinamide after long-term storage. In vitro biological assays indicated antimicrobial activity was retained after spray-drying. Murine pharmacokinetic studies are currently underway.     

Oesophageal atresia: The growth gap

Poor growth is an under-recognised yet significant long-term sequelae of oesophageal atresia(OA) repair. Few studies have specifically explored the reasons for growth impairment in this complex cohort. The association between poor growth with younger age and fundoplication appears to have the strongest supportive evidence, highlighting the need for early involvement of a dietitian and speech pathologist, and consideration of optimal medical reflux management prior to referring for anti-reflux surgery. However, it remains difficult to reach conclusions regarding other factors which may negatively influence growth, due to conflicting findings, inconsistent definitions and lack of validated tool utilisation. While swallowing and feeding difficulties are particularly frequent in younger children, their relationship with growth remains unclear. It is possible that these morbidities impact on the diet of children with OA, but detailed analysis of dietary composition and quality, and its relationship with these complications and growth, has not yet been conducted. Another potential area of research in OA is the role of the microbiota in growth and nutrition. While the microbiota has been linked to growth impairment in other paediatric conditions,it is yet to be investigated in OA. Further research is needed to identify the most,important contributory factors to poor growth, the role of the intestinal microbiota, and effective interventions to maximise growth and nutritional outcomes in this cohort.     

Effect of Dosing Cup Size on the Aerosol Performance of High-Dose Carrier-Based Formulations in a Novel Dry Powder Inhaler

This study investigated how varying the dosing cup size of a novel reservoir dry powder inhaler (DPI) affects the detachment of a micronized active pharmaceutical ingredient from larger carrier particles, and the aerosol performance of a DPI carrier formulation. Three different-sized dosing cups were designed: 3D printed with cup volumes of 16.26 mm³, 55.99 mm³, and 133.04 mm³, and tested with five different carrier type formulations with beclomethasone dipropionate (BDP) concentrations between 1% and 30% (w/w). The morphology of the BDP attached to the carrier was investigated using scanning electron microscopy and the aerosol performance using the Next Generation Impactor. Increasing the volume of the dosing cup led to a reduction of BDP deposition in the Next Generation Impactor preseparator, and an increase in BDP detachment from the carrier was observed, leading to increased aerosol performance. The decreased amount of BDP attached to carrier after aerosolization was attributed to the increased dosing cup void volume. This may enable greater particle-particle and particle-wall collisions, with greater BDP detachment from the carrier and deagglomeration of smaller agglomerates. The dosing cup volume was observed to have significant influence on particle dispersion and the overall aerosol performance of a DPI.     

Human Stimulus Factor Is a Promising Peptide for Delivery of Therapeutics

Fluticasone propionate uptake in the presence of a proprietary cell-penetrating peptide (human stimulus factor, [HSF]) based on the N-terminal domain of lactoferrin was studied, alone and in combination with salmeterol, using an air interface Calu-3 epithelial model. The HSF enhanced uptake and transport of fluticasone propionate across the epithelial barrier when alone and in presence of salmeterol. This was attributed to transcellular-mediated uptake. This HSF is a promising peptide for delivery of therapeutics where enhanced epithelial penetrating is required.