A model system consisting of vacuum-deposited aluminum on glass was developed to demonstrate the effectiveness of cavitational activity (occurring within the cooling water supply of a dental ultrasonic scaler) in the removal of particulate material from solid surfaces. The amount of solid material removed from the model system by this cavitational activity was quantified by a spectrophotometric technique. It was shown that cavitational activity occurring within the cooling water is an important contributory factor in the cleaning efficacy of the ultrasonic scaler operated under conditions similar to those employed clinically.

Aluminum↗

PubMedDate not supplied

Osteoblast viability and detachment following exposure to ultrasound in vitro.

Ultrasound has been used in dentistry for over 40 years and has recently been proposed for cutting bone. The purpose of this study was to establish the effects of ultrasonic instruments on osteoblasts. A 25 kHz magnetostrictive ultrasound generator and a TFI-1 tip (Dentsply, UK) were used as the ultrasound generating instruments. Primary osteoblast cultures were established from the parietal bones of two-day-old Albino Wistar rats grown on tissue culture (TC) petri dishes (Corning, UK) in alphaMEM (Sigma, UK). Once confluent, the osteoblasts were harvested using 0.05% trypsin in 0.02% EDTA then 1.7 x 10(5) cells in 2.5 ml of alphaMEM were either re-seeded immediately onto TC dishes and allowed to adhere for 24 h or kept in suspension before application of ultrasound with different tip displacements prior to re-seeding the cells. Osteoblast viability was assessed using 0.4% Trypan Blue following the initial dose of ultrasound then periodically over a 20 h period for both adherent and suspension osteoblasts. This study demonstrated that ultrasound caused osteoblast detachment and loss of viability in vitro, both when adherent to a substrate or in suspension. Loss of osteoblast viability was related to the maximum displacement of the ultrasonic tip and continued throughout the 20 h period observed for osteoblasts adherent to TC dishes.

Journal Article↗

PubMedDate not supplied

Seating of composite inlays with ultrasonic vibration.

The use of vibration enables the clinician to use high-viscosity luting agents when seating composite inlays and allows quick and efficient placement of the inlay. The film of composite luting agent is achieved in a much shorter time and with lower loads by ultrasonic vibration than using manual methods. In order to achieve a thin lute, the vibrations of the ultrasonic scaler must be directed perpendicular to the surface of the inlay.

Composite Resins↗

PubMedDate not supplied

Investigations into the failure of dental magnets.

PURPOSE: The aim of this study was to determine the mechanisms of failure of magnets used for denture retention. MATERIALS AND METHODS: Magnets were retrieved from dentures that had failed after 4 to 18 months of clinical use. The magnets were sectioned and the failure modes were evaluated using optical or scanning electron microscopy. RESULTS: The magnetic retention system investigated consists of a neodymium-iron-boron magnet sandwiched in a stainless steel keeper, capped with a titanium dome, and sealed with epoxy resin. The diffusion of moisture through the epoxy seal and the breakdown of the encapsulating material led to corrosion of the magnet. In both cases, a loss in retention occurred as the corrosion products weakened the overall magnetic attraction. CONCLUSION: The failure of magnets may occur by either breakdown of the epoxy seal or breakdown of the encapsulating material. Both problems need to be addressed to prolong the life span of these magnets.

Corrosion↗

PubMedDate not supplied

Complete dentures: 1. Treatment planning and preliminary care.

Despite the increasing proportion of the population retaining their natural teeth, there will remain significant numbers of edentulous patients for some time to come. This four-part series aims to help practitioners improve their management of such patients. Part 1 reviews treatment planning and preparation of the mouth, Parts 2-4 will give guidance on impressions and cast preparation; jaw relationships and tooth selection; and insertion, review and denture hygiene.

Aged↗

PubMedDate not supplied

Ultrasonic and sonic scalers.

Explore the source record for details and available documents.

Dental Prophylaxis↗