This article is sponsored content brought to you by NSK.
By Dr Amit Gurbuxani MRACDS (DPH), MDPPH(UWA), BDSc
Over the past 85 years, NSK has drawn on its high-speed rotational know how to continuously innovate its growing range of dental equipment.
The dental handpiece—one of NSK’s core products—plays a key role in the day-to-day operations of any dental practice. We approached Dr Gurbuxani (right) for his take on the evolution of the dental handpiece and its development over the years.
One of the most significant advances in dentistry has been the development of the dental handpiece. The most notable handpiece of the 20th century was a high-speed air-driven contra-angle handpiece introduced by Borden in 1957. Since then air-driven handpiece technology has changed by leaps and bounds. Almost every procedure in dentistry needs a handpiece be it restorative, endodontics, crown and bridge or oral surgery.
The air-driven turbine handpiece has been used in dentistry and was the main workhorse of all handpieces for more than 40 years, due to its relatively low cost, its capacity to rapidly remove tooth structure, and its ergonomic size and low weight. The primary reported disadvantages are its low torque and increased high-frequency vibration that in layman terms is called ‘bur chatter’.
To overcome these disadvantages, the electric handpieces were developed. The electric handpiece has variable power and higher torque than the air-turbine and is designed to maintain a set running speed, with little chance of stalling during tooth preparation. It is also quieter, exhibits less vibration, and provides a precise cut with high concentricity.(1-4)
An electric motor will allow you to set the correct speed, whereas air-driven motors often require a reduction handpiece to attain a slower speed.
Dr Amit Gurbuxani completed his dental degree with honours in 2004 and his Master’s in Dental Public Health at The University of Western Australia (UWA ) in 2010. Along with running a busy private practice at Mi Dental in Perth since 2014, he has been involved with teaching at UWA dental school for almost a decade. He has lectured to undergraduate and graduate students in restorative dentistry and has been nominated numerous times for Excellence in Teaching Awards at UWA.
Awarded his Membership with the Royal Australasian College of Dental Surgeons in 2011, Dr Gurbuxani is also a serving member of the Western Australian Dental Foundation council, and Western Australian ADA (WA) Branch Council and the UWA Dental Alumni council. He has a passion for adopting new technology to improve patient centred care with special interests in minimally invasive dentistry, laser applications in dentistry, utilisation of piezoelectric energy in dentistry, and extended applications of composite resin in tooth rehabilitation.
Re-visiting Gear Ratios
Electric handpieces will have a gear ratio imprinted on the handpiece which helps identify what procedures are best performed with that particular gear ratio. During a dental procedure, a clinician who operates with the right-hand piece at the correct gear ratio will increase his/her work quality.
The best way to identify this is with the international dental colour code on handpieces. This code can be seen most commonly in the form of a band or a coloured dot. A simple description is outlined below:
Blue Band. Air-driven turbine: Ratio of 1:1. Most common handpiece with no increase or reduction in speed. These are most commonly called slow-speed (1:1) handpieces. They would be indicated for caries removal, preparation refinement, and surface finishing.
Green Band. Reduction handpiece which means the handpiece will operate at a lower rpm than the motor. These are used for “ultra” slow-speed procedures such as prophylaxis, pin placement or endodontics with a gear ratio of 4:1, 7:1, 10:1 or 16:1. Recently they have made an emergence in the form of implant motor handpieces (20:1) ratio.
Red Band. Speed increasing handpiece which means the handpiece will operate at a higher rpm than the motor. Typical procedures done with a high-speed (1:5) handpiece would be cavity preparation, crown preparation, and sectioning existing fixed prostheses.
Throughout the years, handpieces have gradually been redesigned and upgraded to become the highly accurate and sophisticated tools they are today. Technological advances continue to improve one of the most fundamental devices used in dentistry.
In conclusion, the design and choice of a dental handpiece is a crucial factor for good ergonomics and efficiency.
1. Choi C, Driscoll CF, Romberg E. Comparison of cutting efficiencies between electric and air-turbine dental handpieces. The Journal of Prosthetic Dentistry. 2010;103(2):101-7.
2. Ercoli C, Rotella M, Funkenbusch PD, Russell S, Feng C. In vitro comparison of the cutting efficiency and temperature production of ten different rotary cutting instruments. Part II: Electric handpiece and comparison with turbine. The Journal of Prosthetic Dentistry. 2009;101(5):319-31.
3. Kumar V, Kalra P. A Study to Analyse the Vibration Transmissibility on Dental Handpieces. i-Manager’s Journal on Mechanical Engineering. 2017;7(3):24-32.
4. Ekenvall L, Nilsson, B.Y., and Falconer, C. Sensory perception in the hands of dentists: Scand J. Work Environ & Health 1990; 16:334-9.