The Dental Handpiece: Technology Continues to Impact Everyday Practice
One of the most fundamental devices used in dentistry, the handpiece can enhance the efficiency of everyday dental tasks. Through 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 these indispensable instruments.
The handpiece is an essential element in any dentist’s armamentarium. It is a fundamental device that can enhance—or hinder, depending on its efficiency and maintenance—the daily routine of a practice. Selecting the right handpiece is critical to helping ensure the smooth operation of everyday activities. The two primary types of handpieces—air-driven and electric—have unique characteristics with specific benefits and drawbacks. Both can achieve excellent results, therefore it is important to understand the differences and advantages of each.
Impact of the Air-Driven Handpiece
Innovations come and go in dentistry, with some being more impactful than others. The introduction of the air-driven handpiece nearly 60 years ago has proven to be a revolutionary advancement that genuinely changed the way dentists prepare teeth to receive dental restorative materials. The use of air-driven “high-speed” handpieces enabled clinicians to work more expeditiously with reduced trauma to the tooth and the patient. This development presented a major improvement from the “belt-driven” handpieces that preceded them and represents one of the most significant leaps forward in the era of modern dentistry.
Since it was introduced in 1957 by Dr. John Borden and DENTSPLY, several notable improvements have been made to the high-speed handpiece to make the design more ergonomic, the heads smaller for easier patient access, the turbines quieter, and bur-changing easier. Low-speed handpieces are now reserved primarily for finishing and polishing procedures, prophylaxis, and laboratory applications. Most dental delivery units contain both a high- and low-speed handpiece to provide the dentist with an instrument whose speed is specific to the operation that is being performed.
Clinical Benefits of Electric Handpieces
Electric handpieces (with variable revolutions per minute [RPM]) are also available that give dentists added benefits when compared to their traditional air-driven counterparts. One significant difference is having a specific RPM, with constant torque and less “bur chatter” (more concentric), so that when polishing or cutting through various types of tooth structure or restorative materials, the bur does not “bog down” or slow down when performing the clinical task. In many clinical situations, an electric handpiece can perform the same functions that both an air-driven high-speed and separate low-speed unit can. Since most clinicians still prefer individual handpieces for high and low speeds so they can be more efficient chairside, this may not make a difference when choosing between the two systems; however, the higher initial investment for electric handpieces may be a consideration for some clinicians. Also, given the ability to “dial in” the desired RPM and use different contra-angles that have different gearing ratios, the electric handpiece can be custom-tailored to perform many other types of clinical procedures such as rotary endodontics, implant placement, and third molar removal (via tooth sectioning), for example. This clinical versatility is very desirable in today’s dental practices where multidisciplinary treatments are becoming increasingly common.
Control panels for electric handpieces are also becoming more automated, allowing the operator to use preset buttons to specifically dial in an RPM for a specific procedure. For example, most polishing procedures should be performed at lower RPM to minimize the generation of heat. Polishing of composite materials can be accomplished efficiently at speeds of 6,000 RPM to 8,000 RPM. Ceramic polishing is generally done in the range of 12,000 RPM to 15,000 RPM. Presets can be made at reduced RPM for caries removal, fine margin refinement on restorative preparations, endodontic cleansing and shaping, and implant drills and placement, to name a few applications. Some models also allow for torque control and have an automatic reversing feature for endodontics. These features eliminate any unpredictability and guesswork compared to using a traditional low-speed unit with only an air-pedal foot control. Having the ability to reverse the rotation of the instrument in an electric handpiece is also a helpful feature when polishing restorations because of the importance of having the polishing instrument rotating from the restorative material toward the tooth to avoid damaging or “ditching” the margin.
Another option is to use the combination of an air-driven handpiece for gross tooth preparation and restoration removal, and an electric handpiece for fine motor preparation refinements and polishing procedures, basically replacing the traditional low-speed handpiece.
Automatic Torque Control in an Air-Driven Handpiece
A recently introduced feature in an air-driven handpiece combines some of the benefits of traditional air-driven and electric handpieces into one instrument. Two new technologies incorporated into this handpiece (Midwest® Stylus™ ATC, DENTSPLY Professional, www.stylusatc.com) are speed sensing intelligence (SSI) and superior turbine suspension (STS). These features allow this handpiece to deliver the benefits of constant torque at high speeds when performing various dental procedures, specifically cutting enamel and dentin and removing or sectioning through different types of restorative materials, including metal and zirconium. According to the manufacturer, some of the benefits of these technologies in an air-driven handpiece are: automatic optimization of power, that is, constant speed under load to avoid stalling; delivery of smooth, constant power and control for maximum cutting efficiency and faster removal of material; speed adjustment of the bur when it is not under load to minimize wear on the bearings; and allowing the handpiece to operate at 330,000 RPM under load without bur chatter or deflection.
Efficient Cutting through Tooth Substrate and Restorative Material
Because an air-driven handpiece with automatic torque control can literally “sense” the degree of “resistance” when cutting through various materials, constant speed and torque are delivered to the cutting instrument, making it unique among traditional high-speed air-driven dental handpieces. In the author's experience, when cutting through enamel, the hardest substance in the body, this type of device gives the operator a fast, efficient cut that leaves the preparation margins ultra smooth. Cutting depth cuts for minimal-preparation veneers entirely in enamel can be performed with precision. As the rotary instrument engages the softer dentin in a preparation, the handpiece “senses” it and reduces the workload on the handpiece while maintaining constant torque. Cutting through restorative materials, from metal amalgam to zirconium substructures, puts a high degree of strain on the turbines of traditional air-driven handpieces and wear on their turbines. Having the ability to automatically adjust speed and torque based on the resistance of the substrate improves efficiency, with less wear and tear on the handpiece itself.
Control during tooth preparation and automatic adjustments in torque to cut enamel and dentin with equal amount of ease and efficiency is, of course, greatly beneficial. However, in a clinical world where dentistry is moving away from metal-based restorative materials towards high-strength porcelain and zirconia restorations, clinicians will need a handpiece that can efficiently remove these materials when they need replacement. Many traditional high-speed handpieces will be strained beyond their limits performing these procedures on a daily basis, which will lead to costly repairs and early replacement.
Finally, proper maintenance is critical for any instrument to perform at its maximum capacity and efficiency. Debris is considered to be one of the main causes of early turbine failure in air-driven high-speed handpiece. Manually spraying handpiece lubricant into the device after each use is inefficient, messy, and not as consistently effective as using an automated system to perform this task. Since the handpiece is an integral part of daily production in the dental practice, it is important that a regular maintenance regimen is performed. Automated handpiece cleaning systems provide precise and consistent cleaning, lubricating, and expelling of debris to keep turbines functioning optimally for longer periods of time. This translates into less need for turbine replacement and minimizes handpiece repair costs.
Because they have no turbine, electric handpieces are lower maintenance units. Older electric handpieces had components called “brushes” that would wear out and need to be periodically replaced; however the newer models are now “brushless,” thus eliminating this issue.
The dental handpiece is a vital part of clinical procedures in every dental operatory. As the scope of procedures increases, as well as the need and demand for more precision and efficiency in dentistry, advancements in handpiece technologies will continue to play a significant part in the practice of dentistry.
The Importance of Ergonomics
The design of a dental handpiece is a crucial factor in good ergonomics. Low back pain, repetitive stress injuries (RSI) such as carpal tunnel syndrome, and various other musculoskeletal disorders (MSDs) are such a significant problem among dentists that the American Dental Association’s Ergonomics and Disability Support Advisory Committee (EDSAC) delivered a report to the Council on Dental Practice (CDP). The resulting document, “An Introduction to Ergonomics: Risk Factors, MSDs, Approaches and Interventions,” focuses on ergonomic risk factors, the various types of MSDs, and practical approaches to ergonomic issues in the workplace. In addition to providing background on ergonomics to promote awareness, the document proposes specific steps relative to ergonomic concerns that are aimed at making the practitioner both more comfortable and more productive.
The document is available online at: http://rgpdental.com/pdfs/topics_ergonomics_paper%282%29.pdf