Frictional resistance exerted by different lingual and labial brackets: an in vitro study

Background

Although much has been written on the implications of friction generated between orthodontic archwires and labial brackets, information on lingual brackets is still limited. Hence, we set out to investigate the frictional resistance exerted by different lingual and labial brackets, including both conventional and self-ligating designs. The effect of various factors, namely bracket/base width, slot size, inter-bracket distance, and first- (ΘcI) and second-order (ΘcII) critical contact angles were evaluated and compared.

Methods

A plaster model of a pretreatment oral cavity was replicated to provide 18 (9 upper and 9 lower) identical versions. The anterior segments of each were taken, and the canine and lateral and central incisors were mounted with either lingual (7th Generation, STb, New STb, In-Ovation L, ORJ) or labial (Mini-Mono, Mini Diamond, G&H Ceramic) brackets. Mechanical friction tests were performed on each type of bracket using a universal testing machine. The maximum force necessary to displace NiTi wires of two different diameters (0.012, 0.014) was measured, using both elastic and metal ligatures with conventional brackets.

Results

The frictional force necessary to displace the wires increased as the diameter of the wire increased in all tested brackets (p < 0.01). Friction was significantly higher (p < 0.001) with elastic ligatures, as compared with metal ones, in all conventional brackets. In the lower lingual group, significantly lower friction was generated at conventional lingual New STb brackets (p < 0.01) and ORJ lingual brackets (p < 0.05) than at self-ligating In-Ovation L lingual brackets. A significant statistical correlation between (ΘcI) and friction was detected in the lower labial bracket group.

Conclusions

Friction resistance is influenced not only by the bracket type, type of ligation, and wire diameter but also by geometric differences in the brackets themselves.

Heparin treatment for allergic conjunctivitis in the experimental BALB/c model

PURPOSE

To compare the inhibitory effects of dexamethasone and heparin on the infiltration of mast cells in the conjunctiva by using a mouse allergic conjunctivitis model.

METHODS

24 Balb/c mice were divided into four groups: allergy group (positive control), dexamethasone group, heparin group, and negative control group, as groups 1, 2, 3, and 4, respectively. Each group comprised 6 mice, and experimental allergic conjunctivitis was developed in groups 1, 2, and 3. The mice in group 2 were treated with topical 0.1% dexamethasone eye ointment, and the mice in group 3 were treated topically with 5,000 IU/ml standard heparin. Both dexamethasone and heparin were instilled once a day for 4 days. Hanks' balanced salt solution was dropped into both eyes of the mice in group 4 instead of dexamethasone or heparin. Eyeballs and eyelids were removed from the mice in all groups while one eye of each animal was used for histopathological, the other for molecular biological examination.

RESULTS

Mast cells, infiltrating the subconjunctival tissue, were significantly lower in group 2 (p < 0.0001), group 3 (p < 0.0001) and group 4 (p < 0.0001) when compared to group 1.

CONCLUSIONS

Topical heparin could be a viable option in treating IgE-induced allergic eye disease since it is found to be as effective as topical dexamethasone in experimental acute allergic eye disease.

Production cross sections of medical 110,111In radionuclides

In this study, production routes of medical 110,111In radionuclides produced by 110Cd(p, n)110In, 111Cd(p, 2n)110In, 112Cd(p, 3n)110In, 107Ag(α, n)110In, 109Ag(α, 3n)110In, 111Cd(p, n)111In, 112Cd(p, 2n)111In, 113Cd(p, 3n)111In, 114Cd(p, 4n)111In, 109Ag(α, 2n)111In, 107Ag(α, γ)111In and 113In(n, 3n)111In reactions have been investigated up to 70 MeV incident particle energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the geometry dependent hybrid model and the cascade exciton model. The full exciton model has also been used to investigate the pre-equilibrium direct effects. Equilibrium effects are calculated according to the Weisskopf–Ewing model. The calculated results are compared with the experimental data taken from the literature.

New calculations of excitation functions of some positron emitting and single photon emitting radioisotopes

In this study, new calculations of the excitation functions of 56Fe(p,2n)55Co,58Fe(p,2n)57Co,60Ni(p,n)60Cu,62Ni(p,2n)61Cu, 68Zn(p,2n)67Ga, 72Ge(p,n)72As,82Kr(p,2n)81Rb, 124Xe(p,2n)123Cs, 112Cd(p,2n)111In and 203Tl(p,3n)201Pb reactions have been carried for incident proton energies up to 50 MeV. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the newly evaluated geometry-dependent hybrid model, hybrid model and the cascade exciton model. Equilibrium effects are calculated according to the Weisskopf–Ewing model. The calculated results are compared with the experimental data taken from the literature.

Morphological features of coronary arteries and lesions in hearts from five species of sharks collected from the northwestern Atlantic Ocean

Morphological features of coronary arteries and incidental lesions are reported from hearts in five species of sharks, the shortfin mako shark, Isurus oxyrhinchus Rafinesque, thresher shark Alopias vulpinus (Bonaterre), blue shark, Prionace glauca L., the smooth dogfish, Mustelus canis (Mitchill), and spiny dogfish, Squalus acanthias L. Sharks were collected from the northwestern Atlantic between June and August from 1996 to 2010. They were necropsied dockside and the hearts were preserved in buffered formalin. Routine sections including ventricle/conus arteriosus and the atrio-ventricular junctions were embedded in paraffin, stained with common histological and immunohistochemical methods and examined by brightfield microscopy. Myointimal hyperplasia, medial myo-myxomatous hyperplasia and bifurcation pads were observed commonly, and medial muscle reorientation and epicardial myeloid tissues were rare. All the above features differed in severity, prevalence and distribution depending on anatomical site and shark species/size. Morphometric analysis indicated that myomyxomatous hyperplasia is associated with luminal narrowing of blood vessels. As suggested previously, the described morphological features are most likely physiological responses to blood flow characteristics. Vascular and cardiac lesions were uncommon and included, granulomatous proliferative epicarditis with fibroepitheliomas, myxomatous epicardial expansions, medial arterial vacuolation, myocardial fibrosis, acute ventricular emboli and parasitic granulomas. The lesions of embolism, proliferative and granulomatous epicarditis and myocardial fibrosis were in all sharks associated with capture events including retained fishing hooks. The significance and aetiopathogenesis of medial vacuolation and epicardial myxomatous expansions remains unclear.

Time-resolved Ellipsometry to Study Extreme Non-equilibrium Electron Dynamics in Nanostructured Semiconductors

We present a femtosecond pump-probe ellipsometer operating over a spectral range of 1.4 – 1.7 eV with a ∼50fs time resolution. The calibration and preliminary findings of the setup are discussed. We tested the apparatus on bulk crystalline silicon (not shown here) and on silicon nanocrystals embedded in an amorphous silicon phase. The ellipsometric angles (ψ, Δ) were determined as a function of time and wavelength. The results suggest that a simple Drude model of free carrier absorption is not sufficient to explain the findings.

New topics in bradykinin research

Bradykinin has been implicated to contribute to allergic inflammation and the pathogenesis of allergic conditions. It binds to endothelial B(1) and B(2) receptors and exerts potent pharmacological and physiological effects, notably, decreased blood pressure, increased vascular permeability and the promotion of classical symptoms of inflammation such as vasodilation, hyperthermia, oedema and pain. Towards potential clinical benefit, bradykinin has also been shown to exert potent antithrombogenic, antiproliferative and antifibrogenic effects. The development of pharmacologically active substances, such as bradykinin receptor blockers, opens up new therapeutic options that require further research into bradykinin. This review presents current understanding surrounding the role of bradykinin in nonallergic angioedema and other conditions seen by allergists and emergency physicians, and its potential role as a therapeutic target.

[Arthroscopic technique using crossed K-wires for avulsion fractures of intercondylar eminence in children]

PURPOSE OF THE STUDY

Avulsion fractures of the intercondylar eminence (ICE) of the tibia have become increasingly frequent in older school age. Due to recent advances in arthroscopic techniques, it is now possible to treat them by minimally invasive methods. This retrospective study presents evaluation of clinical outcomes of an arthroscopic technique using crossed K-wires.

MATERIAL

Thirty-five patients with ICE avulsion fracture, 17 girls and 18 boys at an average age of 13 years (7-18), were included in this study. All were indicated for surgical treatment on the basis of radiographic evidence of McKeever type II and III fractures.

METHODS

The technique of arthroscopic reduction and fixation with crossed K-wires was used. The clinical evaluation of knee stability (anterior drawer test and Lachmann s-test) was made by one clinician. The modified Tegner-Lysholm score was assessed. RESULTS Of the 35 patients, 26 (74%) had minimal knee instability (anterior drawer up to 5 mm), two patients were primarily converted to open reduction with good results, and three (8.5%) experienced temporary knee instability (anterior drawer of 5-10 mm) that resolved spontaneously within 24 months of surgery. Four patients (11.5%) had symptoms of persistent residual instability (anterior drawer more than 10 mm) and were indicated for anterior cruciate ligament reconstruction at a later stage. The average Tegner-Lysholm scores were 86.3/100 and 98.6/100 at 6 and 24 months, respectively. DISCUSSION At the present time at our department, McKeever type II and III avulsion fractures of the intercondylar eminence are indicated for minimally invasive surgical treatment. By exact reduction it is possible to decrease the risk of post-operative knee instability. The current trend is the use of arthroscopy-assisted minimally invasive techniques such as the method of K-wire fixation described here.

CONCLUSIONS

Arthroscopic surgery for ICE avulsion fractures shows good results, is associated with low post-operative risks, is minimally invasive and easy to reproduce. It can be recommended as the method of choice for treating ICE avulsion injury in children.

A comparative study of lingual bracket bond strength

AIM

To compare the adhesive potential, the mechanics implicated in adhesive failure, and the effect on the enamel of four brands of lingual brackets.

METHODS

One hundred sixty premolars and four types of commercially available lingual brackets (STB, ORG, Magic, and Stealth) were selected. Forty brackets per manufacturer were used, half bonded directly and half indirectly. Each of these bonding groups was further subdivided: 10 brackets were bonded without treatment, while the other 10 were sandblasted. Thus, a total of four groups were created for each type of bracket: (a) sandblasted and directly bonded, (b) sandblasted and indirectly bonded, (c) not sandblasted and directly bonded, and (d) not sandblasted and indirectly bonded. Immediately after bonding, each bracket was tested for adhesion strength, and each appliance was then examined via electron microscopy to calculate the ARI.

RESULTS

Statistical analysis showed a significant difference among the four bracket types; a general improvement in lingual appliance mechanical features provoked by sandblasting, albeit with some exceptions; and no significant effect of bonding method on the degree of bond strength. The ARI revealed that the most common area of adhesion crisis was at the adhesive-bracket interface.

CONCLUSION

Overall, STB brackets performed better, and sandblasting proved to be an efficient way of improving the mechanical features of lingual brackets. Bonding technique, on the other hand, did not seem to exert a great influence on bonding success, and the bracket-adhesive interface was identified as the area most prone to failure.

Management of anaphylaxis in primary care: Canadian expert consensus recommendations

BACKGROUND

Anaphylaxis is often managed inadequately. We used findings from a systematic review of gaps in anaphylaxis management to develop evidence-based recommendations for gaps rated as clinically important by a panel of Canadian allergy experts.

METHODS

The nominal group technique (NGT) consensus methodology was used to develop evidence-based recommendations for the management of anaphylaxis in primary care. Physician-specific gaps from our systematic review were prioritized by consensus meeting participants in two rounds, which involved the rating, discussion, and re-rating of gaps. Using current anaphylaxis guidelines, recommendations were then developed for each category of gaps that were identified by the panel as clinically important.

RESULTS

Thirty unique physician gaps from the systematic review were categorized according to gaps of knowledge and anaphylaxis practice behaviors. The panel rated diagnosis of anaphylaxis, and when and how to use epinephrine auto-injectors as clinically important knowledge gaps; and rated infrequent or delayed epinephrine administration, low rate of auto-injector prescription, and infrequent or no referrals to allergy specialists after a reaction as important practice behavior gaps. Evidence from four guidelines was used to support the consensus recommendation statements for three resulting categories of gap themes: anaphylaxis management, epinephrine use, and follow-up care.

CONCLUSION

We used an NGT consensus methodology to develop an educational resource for primary care physicians and allergists to better understand how to manage patients with anaphylaxis. Next steps include testing our findings against observed data in primary care settings and to develop other strategies or tools to overcome gaps in anaphylaxis management.

STUDIES CONCERNING THE SITE OF RENIN FORMATION IN THE KIDNEY : III. THE APPARENT SITE OF RENIN FORMATION IN THE TUBULES OF THE MESONEPHROS AND METANEPHROS OF THE HOG FETUS

1. Renin was found in both the mesonephric and metanephric kidneys of the smallest hog fetuses examined. These were from 17 to 24 mm. in length in the case of the former, and 25 to 49 mm. in that of the latter. 2. No evidence was found in either type of kidney of juxtaglomerular cells described by Goormaghtigh as the probable site of renin formation. 3. The renin content in both the mesonephros and the metanephros was found to be independent of its arteriologlomerular component but directly dependent upon the number, size, and functional state of the tubular component. It increased in amount with increasing tubular proliferation during the course of embryonic development, and decreased with the progressive tubular atrophy and degeneration incident thereto. 4. The site of renin formation is discussed.

STUDIES CONCERNING THE SITE OF RENIN FORMATION IN THE KIDNEY : IV. THE RENIN CONTENT OF THE MAMMALIAN KIDNEY FOLLOWING SPECIFIC NECROSIS OF PROXIMAL CONVOLUTED TUBULAR EPITHELIUM

1. The administration of tartrate to adult rabbits was found to produce in some of them, a profound and widespread necrosis of the proximal convoluted tubular epithelium without affecting the other portions of the nephrons. 2. The markedly damaged kidneys were found to be almost completely devoid of pressor substance (renin), indicating that in the mammalian kidney, the epithelium of the proximal convoluted tubules is concerned in the formation or storage of renin.

STUDIES CONCERNING THE SITE OF RENIN FORMATION IN THE KIDNEY : I. THE ABSENCE OF RENIN IN THE AGLOMERULAR KIDNEY OF THE MIDSHIPMAN FISH

1. The absence of glomeruli in the kidney of the midshipman fish (Porichthys notatus) is reported. 2. The detection of renin in the glomerular kidney of the carp, the catfish, and the hog, and the apparent absence of this substance in the aglomerular kidney of the midshipman fish suggest that the tubular portion of the mammalian kidney does not produce or store renin.