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Aim:The present study was aimed to evaluate the resistance to deformation or fracture of brackets of various materials (ceramic, ceramic reinforced with metal slot, and stainless steel brackets) with archwires during application of torque. Materials and methods:The sample size included 30 brackets of maxillary right central incisor with slot dimension of 0.022 × 0.028˝ and made of three materials (10 of each type):(1) Ceramic brackets (cer), (2) ceramic brackets reinforced with stainless steel slot (cer/ss), and (3) stainless steel brackets (metal). Thirty stainless steel archwire segments of 0.019 × 0.025˝ SS 5 cm in length were used. Elastomeric ties were also used in this study.Results: Highest to lowest deformation or fracture torque found is as follows: Stainless steel brackets (5713.2 gfmm), metal ceramic reinforced with metal slot brackets (4080.8 gfmm), and ceramic brackets (3476 gfmm). Conclusion:Stainless steel brackets showed significantly higher values of torsional load than ceramic brackets reinforced with metal slot and ceramic brackets.Clinical significance: Clinically orthodontic treatment is based on specific force applications to the dentition, the maxilla and the mandible. In order to obtain these forces, orthodontic brackets are attached to the teeth. Most commonly used brackets are metal (stainless steel), ceramic, and combination of metal reinforced ceramic brackets. For successful orthodontic treatment, it is necessary to maintain proper torque and avoid torque loss. Torque loss leads to deepening of bite. Torque loss occurs due to many reasons, one of them being bracket failure to withstand applied torque.

La3+ substituted cobalt ferrite nano-particles with the chemical composition LaxCoFe2-xO4 (here,x=0, 0.05, 0.1, 0.15 and 0.2) were synthesized using auto-combustion method. Structural and morphological studies were probed using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). Formation of rare-earth doped cobalt ferrite was confirmed using the X-ray diffraction studies. Average crystallite size (D) was found to be varying from 43.71nm to 55.37nm with the increase in La3+ concentration. Frequency dependent dielectric properties of synthesized samples were measured from 100 Hz to 1 MHz at room temperature using a precision HIOKI make LCR HI-TESTER. Dielectric dispersion was observed at lower frequencies for the synthesized samples. Magnetic properties were studies using Vibrating Sample Magnetometer (VSM), all the synthesized samples exhibited well defined magnetic hysteresis curves, there by confirming the magnetic behaviour of the sintered samples.

Background: For making a successful prosthesis, it is essential to achieve harmony between the maxillomandibular relationship. The precision and occlusal quality of the prosthesis partly depends on interocclusal bite registration material. Interocclusal bite registration material plays an important role in recording and transferring of existing patient's occlusal records. The procedure used to record and transfer interocclusal relation should be performed with the utmost care and understanding to prevent clinical error. Aim: This study aimed to evaluate the tear strength, compressive resistance and surface hardness of three commercially available bite registration materials . Materials and methods: Three types of commercially available bite registration materials, Bis-acrylate (BA), Polyvinylsiloxane (PVS), and Polyether (PE), were made in Dumbbell and cylindrical shaped samples to evaluate the tear strength and compressive resistance, respectively and were analysed using the universal testing machine. The surface hardness was assessed using a microhardness tester. The obtained data were subjected to statistical analysis using SPSS 16.0 version (Chicago, Inc., USA). ANOVA/Kruskal-Wallis test was used to compare study parameters among the groups. Tukey's post-hoc test was used for intergroup comparisons. Results: Bis-Acrylate exhibited the greatest tear strength, followed by Poly vinylsiloxane and Polyether showed the least tear strength. More compressive resistance was observed in Polyether followed by Bis-Acrylate and lowest in Polyvinylsiloxane. A similar pattern was seen in the surface hardness among the three materials. Conclusion: Bis-acrylate showed greater tear strength and surface hardness, and it can be considered a better bite registration material.