Failure to replace: Who pays the ultimate price?

What criteria do you use when deciding to replace a scaler? The condition of the working end? Broken blades? Your curettes have become sickles from an incorrect sharpening technique or the knowledge of the physical and often irreversible effects on your body when using a scaler that is past its ‘use by’ date? What about the consequences of using a compromised scaler on a patient? Do these facts affect your decision on when to replace?

As an Educator, one of the most frequently asked questions I receive is “How long does a scaler last before it should be replaced?” The answer to this question unfortunately lies within the abyss of answers to questions such as “How long is a piece of string?” or “Where did my other sock go that was in the dryer?” The current recommendation is that when 20% of the instrument blade width or length is reduced or no longer the original design, it is time to replace the instrument. How long it takes for each instrument to reach this threshold is dependent on factors such as:

  • The frequency of use: how many setups of instruments are available and how many times per day each instrument is used, as well as how many days per week are worked
  • Difficulty of patients (quantity and tenacity of the calculus)
  • Use of ultrasonic devices
  • Frequency of sharpening as well as proficiency of sharpening
  • Use of instruments only for the intended use
  • What material the blades are made from (i.e. good quality medical grade steel vs. non-medical grade steel)

Breaking it down: cost per use

Unfortunately, scalers are often looked at as a lifelong part of the office when they should be classified as a consumable commodity in practice assets and order budgeting. Every time a scaler is used, the blade dulls and requires maintenance sharpening. Over time, even proper routine maintenance sharpening will remove metal from the working end of the scaler, reducing it in length and width, in order to restore the blade to the sharp edge needed. Continued usage of a scaler with a length and/or width reduction greater than 20% (Fig. 1) increases the risk of instrument breakage. It also decreases adaptability of the blade to the surfaces the instrument is intended for, leading to tissue trauma and/or operator fatigue. Instruments are ergonomically designed to be used in optimal conditions for both patient and clinician’s comfort and safety. 

Knowing that sharpening removes metal from the blade, one might argue scalers that are sharpened less frequently may have a “longer” lifespan resulting in less frequent replacement and associated costs. However, what are the associated costs and risks of a dull, sub-optimal scaler?

Let’s look at what we already know: An instrument in sub-optimal condition is ineffective and inefficient. The scaler will have reduced tactile sensitivity which can lead to the inability to detect or remove deposits and an increase in the likelihood of a burnished calculus and slipping while trying to remove it. Increased lateral pressure and number of strokes are required to remove the deposits which affects both the patient’s comfort as well as fatiguing the clinician’s hand, wrist, arm and shoulder. The increased number of strokes required can take more time during the appointment than it would to sharpen the instrument prior to use.

In a hypothetical scenario, let’s say a clinician is working five full days per week. The scalers are used and processed two times per day. At the 12-month instrument check – let’s also factor in four weeks of holidays per year where the instruments are not being used – the working end has lost 20% of its length and/or width.  At a price of $55 per instrument, the scaler will cost approximately $0.11 per use. If there are five scalers in your procedural set up, that is only $0.55 per patient. What other consumable commodities do you use in your daily practice that would have an equal value? For example, the average cost of a prophy cup is $0.65. That’s worth more than five instruments!

The costs for the clinician

A literature review2 conducted by Johnson and Kanji in 2016 states that 92% of Dental Professionals reported symptoms in at least one anatomical, upper body region in the past 12 months with dental hygienists being the group most affected (see Fig 2). Work-related musculoskeletal disorders (MSD) in dental hygienists are often blamed on repetitive movements, awkward and static postures, pinch-grasp, forceful exertions, vibration, poor ergonomics and insufficient breaks, among other factors.

So how do dull or compromised instruments contribute to MSD?

Dental hygienists often perform more than 30 repetitive strokes per minute, increasing their risk for muscle strain3,4. Factor in using a small diameter, a heavier weighted handle and/or a dull or sub-optimal blade results in increased pinch-force and lateral pressure required to remove deposits3,5,6,7. Over time, the repetitive strain and cumulative trauma subsequently causes clinicians to seek out both traditional and complementary treatment modalities to manage pain, reduce their workload or in extreme cases, leave the profession due to MSDs 8,9.

And the patient

As previously mentioned, a dull or compromised scaler can lead to increased discomfort and decreased tactile sensitivity due to increased lateral pressure and number of strokes needed to remove the deposits. The cost of burnishing calculus, resulting in iatrogenic and supervised progression of periodontal disease when patients are placing their oral health in our hands, cannot be measured (Figs. 3, 4). Breakage of a blade in a patient’s mouth, with possible need for surgical intervention due to using an over-worn working end, is a preventable situation with a simple and quick check of the working end.

What can we do as dental professionals?

In my tenure as an educator, I have discovered that many practitioners do not sharpen their instruments on a daily basis with the most common reason being that they simply do not have the time. If sharpening is performed routinely, the process should only take a minute or two per kit at each appointment—less time than trying to remove calculus with a dull blade. Scalers should be sharpened before every patient for efficient and effective appointments3. To quote Periodontist Dr. Victor M Sternberg, “Curettes should be replaced regularly, and instrument sharpening is not optional to be a successful (clinician).” Would you use a dull bur to prepare a tooth for a restoration?

Choosing appropriate instruments with considerations for the weight and handle design, wider than 11m with either a criss-cross or knurled surface reduces the need for pinch-grip and over exertion7.

A routine, quick assessment of your scalers is a simple way to ensure neither your nor your patients’ health are being compromised and that you can continue to provide care in a safe and healthy environment. This check can be completed by the clinician or assistant prior to instrument processing. Scalers need to be valued as consumable items to ensure clinicians feel confident and empowered to maintain them without the pressure to try to make them last longer.

Worried about how to dispose of your worn instruments? Hu-Friedy’s Environdent Program is any easy way to recycle any worn instruments. For more information for how it works, visit the Hu-Friedy website at

About the author

Deb (Hume) Brown, RDH, is a dental hygienist with a Grad Dip in Restorative Dental Hygiene. She has worked in a variety of health care settings over the past 30 years in both hospital and private practices providing care in general dentistry, periodontics, orthodontics, TMJ and facial pain. Deb holds a Cert IV TAE and Grad Cert in Clinical Teaching. She was a clinical supervisor, lecturer and examiner at RMIT in Melbourne, Australia, and is currently a clinical supervisor in the BOH program at The University of Melbourne, Australia as well as working in private practice. Deb provides training to Oral Health Professionals on Smoking and Vaping Cessation and has held both Executive and Non-Executive committee positions with the Dental Hygienist’s Association of Australia. Deb is the current Chair for the DHAA’s 2021 National Symposium and sits on its Peer Support Service Committee. She has travelled throughout Australia and New Zealand as an Educational Consultant to deliver programs for Hu-Friedy and EMS Swiss Dental Academy at both Continuing Professional Development events and Universities, teaching Advanced Instrumentation, Instrument Sharpening, Risk Assessment, Periodontal Diagnostics, Ergonomics and Guided Biofilm Therapy to both Hygiene/Oral Health and Dental Students and Professionals. Deb is also a Trainer for the EMS Swiss Dental Academy.


  1. Rucker LM, Sunell S. Musculoskeletal health status in BC dentists and dental hygienists: Evaluating the preventive impact of surgical ergonomics training and surgical magnification. Vancouver: Workers’ Compensation Board of British Columbia;2000. pp. 1–91.
  2. (PDF) The impact of occupation-related… Available from:[accessed Jul 19 2018].
  3. Sanders MA, Michalak-Turcotte C. Strategies to reduce work-related musculoskeletal disorders in dental hygienists: two case Work-related MSDs and dental hygienists 79 Can J Dent Hyg2016;50(2):72-79 studies. J Hand Ther. 2002;15(4):363–7
  4. Branson BG, Black MA, Simmer-Beck M. Changes in posture: A case study of a dental hygienist’s use of magnification loupes. Work. 2010;35(4):467–76
  5. Michalak-Turcotte C. Controlling dental hygiene work-related musculoskeletal disorders: the ergonomic process. J Dent Hyg. 2000;74:41–48
  6. Kerschbaum WE, Liskiewicz T. Cumulative trauma disorders: an ergonomic approach for prevention. J Dent Hyg. 1997;71(4):162–67
  7. Rempel D, Lee DL, Dawson K, Loomer P. The effects of periodontal curette handle weight and diameter on arm pain A four-month randomized controlled trial. J Am Dent Assoc. 2012 Oct;143(19):1105–13
  8. Akesson I, Johnsson B, Rylander L, Moritz U, Skerfving S. Musculoskeletal disorders among female dental personnel —clinical examination and a 5-year follow-up study of symptoms. Int Arch Occup Environ Health. 1999;72:395–403
  9. Crawford L, Gutierrez G, Harber P. Work environment and occupational health of dental hygienists: A qualitative assessment. J Occup Environ Med.2005;47(6):623–32