Effect of Ultrasonic Instrumentation in Treatment of Primary Molars.

AIM: The aim of this study is to describe the protocol used in the treatment of pulpally necrosed primary molars and to evaluate the effectiveness of ultrasonic instrumentation technique in primary dentition. MATERIALS AND METHODS: A total of 50 primary molars in 40 children, ranging from 8 to 10 years of age, were endodonti-cally treated using standard protocols and ultrasonic instrumentation. The follow-up was done for each case ranging from 1 to 2/4 years. RESULTS: Clinical and radiographic controls showed a success rate of 97.5%, considering an evaluation time of 19 ± 9.02 months. CONCLUSION: The use of ultrasonic instrumentation in primary molars with pulpal necrosis succeeded in reducing appointment time and showed a high success rate. CLINICAL SIGNIFICANCE: Ultrasonic instrumentation should be used as a standard protocol in instrumentation of endodontic treatment of primary molars so as to increase the success rate of primary teeth pulpectomies.

An Improved Method of Parameter Identification and Damage Detection in Beam Structures under Flexural Vibration Using Wavelet Multi-Resolution Analysis.

This paper reports on a two-step approach for optimally determining the location and severity of damage in beam structures under flexural vibration. The first step focuses on damage location detection. This is done by defining the damage index called relative wavelet packet entropy (RWPE). The damage severities of the model in terms of loss of stiffness are assessed in the second step using the inverse solution of equations of motion of a structural system in the wavelet domain. For this purpose, the connection coefficient of the scaling function to convert the equations of motion in the time domain into the wavelet domain is applied. Subsequently, the dominant components based on the relative energies of the wavelet packet transform (WPT) components of the acceleration responses are defined. To obtain the best estimation of the stiffness parameters of the model, the least squares error minimization is used iteratively over the dominant components. Then, the severity of the damage is evaluated by comparing the stiffness parameters of the identified model before and after the occurrence of damage. The numerical and experimental results demonstrate that the proposed method is robust and effective for the determination of damage location and accurate estimation of the loss in stiffness due to damage.