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The problem of vibration isolation by rectangular open trenches in a plane strain context is numerically studied using a fi nite element code, PLAXIS. The soil media is assumed to be linear elastic, isotropic, and homogeneous subjected to a vertical harmonic load producing steady-state vibration. The present model is validated by comparing it with previously published works. The key geometrical features of a trench, i.e., its depth, width, and distance from the source of excitation, are normalized with respect to the Rayleigh wavelength. The attenuation of vertical and horizontal components of vibration is studied for various trench dimensions against trench locations varied from an active to a passive case. Results are depicted in non-dimensional forms and conclusions are drawn regarding the effects of geometrical parameters in attenuating vertical and horizontal vibration components. The screening effi ciency is primarily governed by the normalized depth of the barrier. The effect of width has little signifi cance except in some specifi c cases. Simplifi ed regression models are developed to estimate average amplitude reduction factors. The models applicable to vertical vibration cases are found to be in excellent agreement with previously published results.

Conventional nonsurgical endodontic treatment has a high degree of clinical success, but in certain cases surgical intervention becomes necessary. This is the case report of a patient presenting with bilaterally separate periapical lesions in the maxillary anterior region. One lesion was managed by periapical surgery using a novel and safe method of separating the soft tissue mass of the periapical lesion which was in proximity to vital and vulnerable anatomical tissues, and the other was managed by long-term intracanal medicament, emphasizing the need of application of treatment in the best interest of the patient.

A dazzling white smile has been a symbol of beauty, health and vitality for hundreds of years. Discolouration, especially when the front teeth are affected, means a significant disturbance of aesthetics and can decrease a patient’s self esteem. Public demand for aesthetic dentistry, including tooth whitening, has increased in recent years. Compared with restorative treatment modalities, whitening, also referred to as bleaching, is the most conservative treatment for discolored teeth. This public demand for a whiter smile and improved aesthetics has made tooth whitening a popular and often requested dental procedure, since it offers a conservative treatment option for discolored teeth. Whitening often enhances the treatment and encourages patients to seek further aesthetic treatment. Dental bleaching offers a conservative, simplified, and low cost approach to change the color of discoloured teeth. Current bleaching techniques include a dentist-prescribed in-office technique, an at-home applied technique, or a combination of both. The pigments oxidation is responsible for tooth bleaching and can be carried out with two different products; carbamide peroxide and hydrogen peroxide. This case report reflects the remarkable change of tooth color by in-office bleaching.

Standard Penetration Test (SPT) is one of the most commonly used methods of geotechnical subsurface exploration. The soil parameters for design of building foundations are frequently based on SPT results. The accuracy of measurement of SPT blow count (N-Value), therefore, highly influences the design and construction of foundations of structures. Although there are uncertainties involved in the determination of N-Value inherent to the procedure of the test, these can be minimised by maintaining close adherence to the accepted standard method of testing and instrumentation. In this work a series Standard Penetration Tests were carried out using a non-standard (damaged due to prolonged use) sampler cutting shoe and the results were compared with N-values obtained by using a standard sampler shoe. The effect of using the overused sampler shoe on SPT value is presented.