ABSTRACT
BACKGROUND: Bond strength of orthodontic composite is strongly influenced by molecular and structural mechanisms. Aim of this in vitro study was to compare bond strength of light-cure orthodontic composites by measuring debonding forces and evaluating locations of bond failure. Investigations on chemical compositions clarified adhesive behaviors and abilities, exploring effects of ageing processes in this junction materials. METHODS: Twelve enamel discs, from human premolars, were randomly coupled to one orthodontic adhesive system (Transbond XT™ 3 M UNITEK, USA, Light-Cure Orthodontic Paste, LEONE, Italy and Bisco Ortho Bracket Paste LC, BISCO, Illinois) and underwent to Shear Bond Strength test. Metallic brackets were bonded to twenty-seven human premolar, with one of the adhesive systems, to quantify, at FE-SEM magnifications, after debonding, the residual material on enamel and bracket base surfaces. Raman Spectroscopy analysis was performed on eight discs of each composites to investigate on chemical compositions, before and after accelerated aging procedures in human saliva and sugary drink. RESULTS: Orthodontic adhesive systems showed similar strength of adhesion to enamel. The breakage of adhesive-adherent bond occurs in TXT at enamel-adhesive interface while in Bisco and Leone at adhesive-bracket interface. Accelerated in vitro aging demonstrated good physical-chemical stability for all composites, Bisco only, was weakly contaminated with respect to the other materials. CONCLUSION: A similar, clinically adequate and acceptable bond strength to enamel for debonding maneuvers was recorded in all orthodontic adhesive systems under examination. No significant chemical alterations are recorded, even in highly critical situations, not altering the initial mechanical properties of materials.
Subject(s)
Dental Bonding , Orthodontic Brackets , Dental Cements , Dental Stress Analysis , Humans , Italy , Materials Testing , Resin Cements , Shear Strength , Stress, Mechanical , Surface PropertiesABSTRACT
Giomer is a relatively new class of restorative material with aesthetics, handling and physical properties of composite resins, and benefits of glass ionomers: high radiopacity, antiplaque effect, fluoride release, and recharge. To verify the superior properties of Giomers, in this study, a deep morphological characterization has been performed with an in vitro comparative study among a Giomer (Beautifil® II by Shofu Dental Corporation, Osaka, Japan), a Compomer (Dyract Extra by Dentsply, Caulk, Germany), glass ionomer cement (Ketac fil plus by 3M ESPE), and a composite resin (Tetric Evoceram by Ivoclar). In particular, mechanical and optical properties and ageing effects have been compared to investigate materials similarities and differences. Indentation tests, UV-Visible spectroscopy, Raman spectroscopy, and weight loss after storage in saliva or sugary drink have been carried out to analyze materials behavior in real conditions. The results confirm the high quality of Giomer material and indicate possible improvements in their usage.
Subject(s)
Dental Materials/chemistry , Humans , Spectrophotometry, Ultraviolet , Spectrum Analysis, RamanABSTRACT
In this paper we present a miniature electrolytic pump sensorized with a novel strain sensor to be used as active component of a drug delivery system. It consists of an electrolytic solution reservoir where inert electrodes are immersed. By polarizing the electrodes, the electrolytic reaction is activated and the produced gases (i.e. oxygen and hydrogen) displace an elastic membrane delimiting the electrolytic solution reservoir. In order to measure and monitor the membrane displacement, and therefore the volume of drug ejected, a strain gauge sensor has been prepared using a conductive thermoplastic nanocomposite elastomer (CTPE). The sensor has been fixed on the deformable membrane. The conductive thermoplastic elastomer is a good candidate for this application because of its high sensitivity. Furthermore, the CTPE allows to customize the resistance of the device in order to obtain low power consumption.
Subject(s)
Drug Delivery Systems/instrumentation , Electrolysis/instrumentation , Nanocomposites/chemistry , Elastomers , Electrodes , Equipment DesignABSTRACT
The effect of prostaglandin E2 (PGE2) (3 mg/day orally for four days) on puerperal breast discomfort and prolactin secretion was investigated in eight women in a double-blind, placebo-controlled study. Scoring systems were used for daily assessment of the degree of breast discomfort. PGE2 had no effect on breast lactation, breast swelling or pain. No difference was seen between serum prolactin in the placebo- and PGE2-treated women. Contrary to a previous report, in our experimental design PGE2 had no effect on puerperal breast lactation, swelling or pain or on serum prolactin.
Subject(s)
Breast/drug effects , Pain/drug therapy , Postpartum Period , Prolactin/metabolism , Prostaglandins E/pharmacology , Adult , Breast/metabolism , Dinoprostone , Female , Humans , Lactation/drug effects , Pregnancy , Prolactin/blood , Time FactorsABSTRACT
The effect of naloxone (1.4 mg/hr for 3 hours) on subjectively experienced menopausal flushes, skin temperature, and luteinizing hormone secretion was investigated in seven women in a double-blind, saline-controlled, crossover study. Naloxone had no effect on the number of subjective flushes, episodic skin temperature elevation, luteinizing hormone pulses, variability of luteinizing hormone secretion, or total luteinizing hormone secretion. This study suggests that a naloxone-sensitive opioid mechanism is not active in modulating luteinizing hormone secretion in the postmenopausal woman and that opioid receptor blockade is not effective in altering the frequency of menopausal flushes.
