The performance characteristics of a piezoelectric ultrasonic dental scaler

Development of New Method to Reposition Orthodontic Brackets Without Debonding by Using an Ultrasonic Device: An In Vitro Study

Objective:

The purpose of this study was to develop a new method to change a bracket position without debonding the metal bracket that was bonded with a polymethyl methacrylate (PMMA) orthodontic adhesive resin by using an ultrasonic device.

Materials and Methods:

An originally designed scaler tip was developed for a piezoelectric ultrasonic scaler. The adhesive turned to melting state by thermal heat that was generated by ultrasonic frictional heat. When the adhesive was in melting state, the bracket was rotated approximately 20° and held in this position until the adhesive hardened again by air cooling. Shear bond strengths were measured on each sample in the control and the repositioning groups. To evaluate the thermal effects of the increased temperature on the enamel surface and pulpal cavity, extracted human lower premolars were monitored during the repositioning time.

Results:

The time required for the repositioning procedures was approximately 7 s. The temperature of the enamel surface increased by 53°C and the pulpal wall increased by 0.5°C during the repositioning procedures. The bonding strength showed no significant difference between the control and repositioning groups.

Conclusion:

This method for bracket repositioning without debonding using an ultrasonic device proved to be a new method for bracket repositioning.

On the use of ultrasonic dental scaler tips as cleaning technique of microfiltration ceramic membranes

The use of ultrasonic dental scaler (UDS) tips has been investigated for cleaning ceramic membranes fouled when filtering cactus juice. Thin and long tips having a larger coverage exhibited the best performance for removing the cake layer deposited on the membrane surface. Such tips cleaned an area equivalent to almost one third of total area of the membrane surface. However, the cleaned area could be increased notoriously if the membrane were placed in rotatory disc holder. The resistance-in series model and atomic force microscopy (AFM) technique helped to reveal the effect of the UDS tips as cleaning process of ceramic membranes. The reversible resistances estimated for UDS tips were 58% and 17% lower than the ones obtained by chemical cleaning at transmembrane pressures of 0.3 bar and 0.5 bar, respectively. This was corroborated by microscope images, which showed the detachment of cake layer of the membrane surface. Results of this work showed that UDS tips are an innovative option as cleaning strategy for filtration membranes.

Which Parameters Affect Biofilm Removal with Acoustic Cavitation? A Review

Bacterial biofilms are a cause of contamination in a wide range of medical and biological areas. Ultrasound is a mechanical energy that can remove these biofilms using cavitation and acoustic streaming, which generate shear forces to disrupt biofilm from a surface. The aim of this narrative review is to investigate the literature on the mechanical removal of biofilm using acoustic cavitation to identify the different operating parameters affecting its removal using this method. The properties of the liquid and the properties of the ultrasound have a large impact on the type of cavitation generated. These include gas content, temperature, surface tension, frequency of ultrasound and acoustic pressure. For many of these parameters, more research is required to understand their mechanisms in the area of ultrasonic biofilm removal, and further research will help to optimise this method for effective removal of biofilms from different surfaces.