Evaluation of shear bond strength with different enamel pretreatments: an in vitro study.

CONTEXT: Bonding procedures are time consuming and debonding of brackets is a common problem encountered in orthodontics. AIMS: The purpose of this in vitro study was to evaluate the shear bond strength (SBS) with different enamel pretreatment (acid etching, air abrasion, and bur abrasion) to enhance the bonding performance. SUBJECTS AND METHODS: A total of 60 extracted premolars for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group I - conventional etching with 37% phosphoric acid; Group II - air abrasion with 50 µm aluminum oxide; and Group III - bur abrasion with diamond fissure (#330, MANI, Dia-Burs, New Jersey, USA). After storing the specimens for 24 h in distilled water at 37°C, SBS was measured with Universal testing machine (Lloyd Universal testing machine-Model No. L.R 100K, UK). The shear force at a crosshead speed of 1 mm/min was transmitted to brackets. The adhesive remnant index (ARIs) scores were recorded after bracket failure. STATISTICAL ANALYSIS USED: Descriptive statistics, multiple comparisons of the SBS of different groups, were performed by analysis of variance. The Tukey's test was used to evaluate differences in ARI scores between groups. All statistical evaluations were calculated using the Statistical Package for Social Sciences Windows, release 10.0.0 (SPSS Inc., Chicago, Illinois, USA). RESULTS: The analysis of SBS variance (P < 0.01) and Chi-square test of ARIs scores (P < 0.01) revealed significant differences among three groups tested. The SBS in Group I (mean: 8.822 ± 0.92 MPa) and Group III (mean: 6.015 ± 0.87 MPa) was significantly higher than Group II (mean: 3.824 ± 0.57 MPa). The ARI was used to evaluate the residual adhesive on the enamel after bracket removal. The Tukey's test was used to evaluate differences in the ARI scores among the groups. CONCLUSIONS: The current findings indicate that enamel surface preparation using bur abrasion results in a significant higher than air abrasion; within the limitations of this study recommend bur abrasion as a viable alternative to acid etching.

Evaluation of nickel ion release from various orthodontic arch wires: An in vitro study.

AIM: The high incidence of nickel (Ni) allergy and the increasing use of Ni-containing dental biomaterials have been of growing concern. The purpose of this investigation was to analyze and evaluate the rate of Ni ion release from different types arch wires used in orthodontics. MATERIALS AND METHODS: Four groups of arch wires (nickel titanium [NiTi], SS, Cu NiTi and ion implanted NiTi) with twelve samples were stored in artificial saliva with a pH 5.6-7.0 thermostated at (36.5°C) and tested at different intervals i.e., 7(th) day, 14(th) day, and 21(st) day. The amount of Ni and Ti ions released from the sample were evaluated using an atomic adsorption spectrophotometer. The solution was replaced with a fresh bottle to avoid sediments. RESULTS: Statistical analysis was performed by nonparametric tests (Student's paired t-test, one-way analysis of variance and multiple comparison test by Tukey "Honestly significant difference"). The statistical package SPSS PC plus (version 4.0.1) was used for data processing and statistical analysis. Results showed significantly statistical influence on the release amount of Ni and Ti ions. Large variation in concentration of Ni released from brackets and bands combined. However, the amount of Ni ions released in all test solutions diminished with time and was below the critical value necessary to induce allergy and below daily dietary intake level. CONCLUSIONS: The daily release of NiTi, SS, Cu NiTi and ion implanted NiTi by an orthodontic appliance in acid pH, particularly favorable to corrosion, was well below that ingested with a normal daily diet. It is therefore concluded that the quantities of metal ions released in our experimental conditions should not be cause for concern in utilizing the appliance.

Distal revascularization and interval ligation (DRIL) procedure requires a long bypass for optimal inflow.

BACKGROUND: Distal revascularization and interval ligation (DRIL) is commonly used to treat ischemic steal syndrome caused by arteriovenous hemodialysis access and has been associated with good outcomes. However, the literature lacks technical details of a successful intervention. We tested the hypothesis that a brachial-level arteriovenous fistula (AVF) generates a zone of low arterial blood pressure in the brachial artery near the AVF origin. METHODS: We identified patients with ischemic steal syndrome caused by an AVF originating from the brachial artery level who were eligible for the DRIL procedure. All patients were studied with invasive pressure monitoring in the brachial artery at the time of digital subtraction angiography. We measured systolic, diastolic and mean arterial blood pressure at 5 cm intervals from a point in the arterial circulation 5 cm distal to the origin of the AVF and continuing proximally into the subclavian artery. RESULTS: Our series involved 10 patients with a mean age of 66.5 (range 53-81) years. Four patients were women and 8 had diabetes. All patients had grade 3 ischemic steal syndrome with ischemic rest pain and/or ischemic tissue loss. Mean systolic, diastolic and arterial pressures increased from the level of the AVF until central pressures were reached. Systolic blood pressure was significantly lower than central blood pressure until a level 20-25 cm proximal to the AVF. CONCLUSION: The benefits of the DRIL procedure in alleviating ischemic steal syndrome associated with hemodialysis access are best achieved with a DRIL bypass for which inflow originates at least 20-25 cm proximal to the origin of the AVF.

CONTEXTE: On utilise souvent la revascularisation distale avec ligature intermédiaire (DRIL) pour traiter le syndrome d'hémodétournement ischémique causé par une fistule artérioveineuse pour hémodialyse et elle a été associée à de bons résultats. Or, la littérature donne peu de détails techniques sur les interventions réussies. Nous avons voulu tester l'hypothèse selon laquelle une fistule artérioveineuse (FAV) brachiale génère une zone de tension artérielle réduite dans l'artère brachiale près de la naissance de la FAV. MÉTHODES: Nous avons recensé des patients porteurs d'un syndrome de détournement ischémique causé par une FAV de l'artère brachiale qui étaient admissibles à l'intervention DRIL. Nous avons examiné les patients par monitorage endovasculaire de la pression de l'artère brachiale sous angiographie numérique avec soustraction. Nous avons mesuré les tensions artérielles systoliques, diastoliques et moyennes à des intervalles de 5 cm, à partir d'un point distal de la circulation artérielle éloigné de 5 cm de la naissance de la FAV, puis proximalement, jusqu'à la sous-clavière. RÉSULTATS: Notre série a regroupé 10 patients âgés en moyenne de 66,5 ans (de 53 à 81 ans). Quatre patients étaient des femmes et 8 souffraient de diabète. Tous les patients étaient porteurs d'un syndrome d'hémodétournement ischémique de grade 3 accompagné de douleur ischémique au repos et/ou d'ischémie tissulaire. Les tensions artérielles systoliques, diastoliques et moyennes allaient croissant à partir de la FAV, jusqu'à l'atteinte des tensions centrales. La tension systolique s'est révélée significativement plus faible que la tension centrale jusqu'à un point proximal situé à 20­25 cm de la FAV. CONCLUSION: Dans le traitement du syndrome d'hémodétournement ischémique associé à une fistule artérioveineuse pour hémodialyse, les avantages de l'intervention DRIL sont plus marqués avec un pontage dont l'influx tire son origine à au moins 20­25 cm de la naissance de la FAV.