Heat, generated during the drilling of a dental implant site preparation, leads to a temperature rise and consequently to a thermal injury of the bone tissue surrounding the implant site, which can cause the subsequent implant failure. In this article, we present new findings related to the temperature rise during implant site drilling under real conditions on a bovine rib bone specimen. The experiments were designed with the help of a full-factorial design in randomized complete blocks, where the main effects of the drill diameter in combination with the drilling force and the drilling speed, and their interactions, on the temperature rise were determined. The temperature rise in the bone under real conditions was measured as the implant site was being prepared by a dentist using intermittent, graduated drilling and external irrigation. Results show that the drill diameter has statistically significant effect, independent of the drilling procedure used. Among the examined drilling parameters, the drill diameter has the greatest effect, where an increase in the drill diameter first causes a decrease in the temperature rise and further increase in the drill diameter causes its increase. During the continuous and one-step drilling, the temperatures of the bones were up to 40.5 °C and during the drilling under actual conditions up to 30.11 °C.
Pressure sensors often have to be placed at a certain distance from the measured object, which means that the fluid in any connecting tube and the volume of the sensor represent a constituent part of the pressure measurement system. This paper deals with improvements to the modelling of the frequency characteristics of such systems using gases or liquids as the pressure transmission fluids. The Bergh–Tijdeman mathematical model, which represents the state of the art for studying the dynamics of pressure measurement systems with a connecting tube, was supplemented with contributions from thermodynamic effects in the sensor volume and the compliance effects of the connecting tube. The results show that the thermodynamic effects can have a significant influence on the predicted frequency response of gas-filled systems, typically leading to a considerable increase of the damping ratio. The compliance is usually important to consider when modelling liquid-filled systems. In addition, this paper aims to study the validity of approximate, second-order and first-order models of the pressure measurement system. We derived analytical approximations for the corresponding lumped-parameters, i.e. the natural frequency, the damping ratio and the time constant, and identified some discrepancies in the analytical expressions that are often used in the literature.
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