ContextVarious restorative materials are introduced in dentistry to achieve adequate strength and restore aesthetics. Dental amalgam is a versatile material with self-sealing property, but is unaesthetic. Other restorative materials like composites require conservative preparation, but exhibit polymerisation shrinkage resulting in microleakage. To overcome these drawbacks, a high strength restorative material reinforced with ceramic and zirconia fillers known as Zirconomer (Shofu Inc., Japan) has been introduced.AimsThis in vitro study aims to evaluate and compare the microleakage of zirconia-infused glass ionomer cement (Zirconomer) with Miracle Mix (GC Fuji Miracle Mix, Japan) and amalgam.Materials and methodsIn this in vitro study, 30 non-carious premolar teeth were randomly divided into three groups (n=10) depending on the restorative material used—Silver Amalgam (DPI, India), Miracle Mix, and Zirconomer. Standard Class V cavities were prepared on the buccal surface of 30 non-carious extracted premolars. The restored teeth were thermocycled and then immersed in 2% methylene blue dye for 24 hours. All teeth were bisected longitudinally in a buccolingual direction and observed under a stereo microscope at 40X magnification for the evidence of dye penetration. The data were analyzed using one-way analysis of variance (ANOVA) and Kruskal-Walis tests (p<0.01).ResultsZirconomer showed the least microleakage in Class V cavity restoration with a statistically significant difference to amalgam and Miracle Mix.ConclusionsZirconomer has proven to be an excellent restorative material as it showed the least microleakage followed by Miracle Mix and amalgam. Zirconomer raises the bar for restorative reinforced glass ionomers by outperforming conventional glass ionomers and amalgam restoration.
Background and objectivesFriction between the bracket and archwire during sliding mechanics is of great concern in orthodontics, as it reduces the effectiveness of the orthodontic appliance and slows down tooth movement. The aim of this study was to evaluate frictional resistance of stainless steel (SS), titanium molybdenum alloy (TMA), and Connecticut new arch (CNA) wires against SS and ceramic brackets. The surface textures of the brackets and wires were also evaluated by scanning electron microscopy (SEM) before and after testing.MethodA total of 180 premolar brackets of SS (ORMCO Corp., Orange, CA) and 180 ceramic (3M Unitek, Maplewood, MN) with a 0.022-inch slot and 180 SS, TMA, and CNA wires of 0.017 x 0.025 inches and 0.019 x 0.025 inches were tested. The SS brackets and ceramic brackets were bonded onto the SS bar with cyanoacrylate adhesive with the help of a jig. The wire assembly was vertically mounted and clamped to the jaws of the universal testing machine with 10 N load cell, and friction was measured along with other readings. The surface roughness of brackets and wires were examined using SEM in 200 X magnification before and after testing.ResultsTMA wire showed the greatest frictional force compared to SS and CNA wire. The frictional force was greater in the 0.019 x 0.025-inch wire compared to the 0.017 x 0.025-inch wires. The highest frictional force was noted in the SS bracket and 0.019 x 0.02-inch TMA wire combination. A statistically significant difference was not seen between the SS bracket and 0.019 x 0.025-inch SS wire and the 0.019 x 0.025-inch CNA wire combinations.SEM showed that the TMA archwire had the roughest surface area compared to SS and CNA wires, and the ceramic bracket had more surface roughness than the SS bracket.ConclusionCNA wire demonstrated frictional resistance similar to the SS wire. CNA wire can be used instead of TMA wire because of its better range of action, high spring back, and less frictional resistance for space closure in sliding mechanics.
IntroductionSpace closure by molar protraction has always been a challenge in orthodontic treatment due to larger root surface area which requires additional anchorage. Ideally, there should be little or no tipping. However, the protraction forces, being occlusal and buccal to the centre of resistance (CR) of the tooth, cause tipping and rotations.AimThe aim of the study was to assess the effect of bracket slot and archwire dimensions on posterior tooth movement during space closure in sliding mechanics and evaluate the length of power arm to bring about translatory movement of teeth using three-dimensional finite element analysis.Materials and methodsA model of the maxillary teeth was created and converted to a finite element format through a meshing software, Hypermesh. Two three-dimensional models, each with a combination of 0.017”× 0.022” archwire in 0.018” slot (model 1) and 0.019”×0.025” archwire in 0.022” slot (model 2), were generated. Power arms of different lengths were attached to the first molar. Miniscrew was inserted between the canine and first premolar.ResultsIn model one, the power arm of 10-mm height provided controlled tooth movement than the one with 6 mm height, and in model two, power arms of both 6-mm and 10-mm height produced controlled tooth movement.ConclusionsAs the force was raised apically from the slot, more translation was observed. Power arm of 6-mm height can be used due to anatomic limitation of the vestibule.
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