Dental Hand Piece- The Turbine

Abstract

Dental air turbine handpieces have been widely used in clinical dentistry for over 30 years, yet little work has been reported on their performance. A few studies have been concerned with measurement of speed (i.e. rotation rate), torque and power performance of these devices, but neither investigations of functional relationships between controlling variables nor theory dealing specifically with this class of turbine have been reported. This has hindered the development of satisfactory methods of handpiece specification and of testing dental rotary cutting tools. It was the intention of the present work to remedy that deficiency. Dental turbines driven by compressed air and capable of free running speeds above 300 000 rpm have been widely used for rotary cutting work in dentistry ever since their introduction in 1957. The rotor, contained within the head of the handpiece, typically has a diameter in the range 3.5-5.6 mm and most current designs incorporate ball race bearings [3]. A few air bearing designs are still available although over recent years these have become much less widely used in clinical practice [3]. Turbine handpieces are currently used as the main means of cutting tooth structure and restorative materials in a wide range of dental

operations.

Table of Contents

Abstractii

Introduction1

BioMechanics of Dental Handpiece3

Kavo635B5

Star4306

Midwest Tradition6

Pro Drive dental hand-pieces7

Conclusion9

End Notes11

Dental Hand Piece- The Turbine

Introduction

The dental drill is a tool used by dentists to bore through tooth enamel as well as to clean and remove plaque from the tooth's surface. It is composed primarily of a handpiece, an air turbine, and a tungsten carbide drill bit. Since its development began in the mid 1700s, the dental drill has revolutionized the field of dentistry. The modern dental drill has enabled dentists to work more quickly and accurately than ever before, with less pain for the patient. [1]

Dental handpiece turbines are small, very specialized air driven turbines used in both high and low speed dental handpieces.

High speed dental handpieces turn at approximately 400,000 revolutions per minute (rpm). Slow speed dental handpieces turn at approximately 5,000 rpm to 20,000 rpm. Because of the specialized nature, very high speeds, and extremely rigorous use of dental handpieces, the turbines that drive them must be manufactured to the highest standards. Substandard materials would result in imminent failure, and possible harm to the patient on which the equipment was being used.

Torque, power and efficiency characterization

The general behaviour and characterization of dental air turbine handpiece performance has not hitherto been described. An earlier paper dealt with the flow and free running speed characteristics of these devices. This paper continues the analysis of performance by considering torque, power and efficiency and concludes with the definition for the first time of a set of figures of merit which may be used to assess performance. The control of the gas supply and rotation measurement, the fibreoptic tachometer system used to monitor rotation rate, and gas flow monitoring were all as before. An XYY (2-channel) chart recorder (5000 Series, Gould, Cleveland, OH, USA [system gain accuracy ...