by Anne Nugent Guignon, RDH, MPH
For nearly a century, hand scaling was the cornerstone for how real hygienists dealt with hard and soft deposits. Our thinking about this basic sacred cow tenet of clinical dental hygiene has shifted dramatically over the past decade.
Another professional sacred cow is also under scrutiny: brushing and flossing. We tend to teach patients until their eyes glaze over. Many of our patients have heard our speeches so often they can repeat the harangue verbatim, and they learn to quickly tune out the traditional admonitions.
Like automatons, many clinicians became convinced that hand scaling and a few bristles or thread-like pieces of string were superior techniques for disrupting the pathogenic slime we now know as plaque biofilm. Unfortunately, some practitioners have not moved forward to embrace new scientific findings.
Research describes the ongoing, insidious effects of plaque biofilms on hard and soft oral tissues. This is not new to observant clinicians. We know that patients with fragile immune systems respond differently to plaque biofilm than say, healthy 19-year-old college sophomores.
Biofilms are highly evolved intricate communities populated by interdependent microbial species. Complex biofilm communities grow and thrive in hard deposits as well as on tooth structures devoid of clinically detectible calculus. Biofilm experts tell us that it is difficult to remove these tenacious bacterial communities mechanically, and biofilms resist penetration by antimicrobial agents.
Since we now understand that the real enemy is a sticky, complex mass, how can we best disrupt this living mass of pathogenic slime? Power-driven scaling instruments, classified as ultrasonic scalers, create fluid cavitation via the sound wave (acoustic) energy that surrounds an activated ultrasonic scaler tip. This acoustic energy creates tiny bubbles in the surrounding irrigant that implode, causing disruption of both hard and soft deposits on the tooth surface.
Sonic devices can assist clinicians in hard deposit removal. Contrary to popular belief, only true ultrasonic scalers such as piezo electric and magnetostrictive units create cavitation. Vibrations from sonic power scalers, which attach directly to a slow speed air hose, are not sufficient to create true cavitation.
From Point A to Point B
Many clinicians assume that all power scalers work the same and produce the same clinical outcomes. For those working with unaided vision, this is a logical outcome. Nothing could be further from the truth. A perfect analogy is cars. Certainly there is no argument that a car in any class can take a driver from point A to point B, but there are definite differences between vehicle reliability, durability, safety and comfort. A 100-mile drive across Texas in the middle of July in an un-air-conditioned economy car would be a dramatically different experience than taking the same trip in a mid-priced or premium vehicle with a fully adjustable climate control system.
Extend the car analogy to engines and transmissions. Just for fun, imagine that piezo units have diesel engines and magnetostrictive units have combustion engines. The activated tips on either type of ultrasonic scaler have the capacity to disrupt plaque biofilm beyond the terminal end of the insert. They also remove stain and hard deposits; however, the movement of a piezo tip is quite different from that of a magnetostrictive tip, just as the mechanical action of a diesel engine is different from a combustion engine.
Piezo tips move in a back and forth linear motion. When the lateral surface of a piezo tip is adapted to the tooth, the motion is smooth and soft, much like moving an eraser across a chalkboard. The concave and convex surfaces of an activated piezo tip can disrupt deposits, but the feel is more aggressive, noisy, and requires clinicians to assume awkward hand positions to properly adapt the activated tip to some tooth surfaces. Recent advances in one manufacturer’s piezo generator and tip technologies provide smoother tip vibrations when using the convex or concave insert surface.
Magnetostrictive tips vibrate in an elliptical, figure eight pattern. Because of this motion, there is less variation in how different magnetostrictive insert surfaces feel on a tooth, compared to the linear motion of a piezo tip. This does not mean one technology is superior to another, just that the feel of an active insert tip is different between the magnetostrictive and piezo electric tips.
Whether one chooses to use a magnetostrictive or piezo electric unit, the configuration and diameter of the actual ultrasonic insert tip is a key factor in clinical application. Larger diameter insert tips have a more robust feel and are favored for efficient deposit removal, especially tenacious deposits. However, what’s gained in time savings can be negated by increased patient discomfort, especially on hypersensitive roots. In addition, more water is required for the larger, thicker tips, especially when operated at higher power (amplitude) levels. Three problems arise when more fluid irrigant is used - decreased visual acuity, increased potential for gagging, and increased production of contaminated fluid aerosol that is difficult to manage.
The Impact of Slimmer Tips
The advent of newer, slimmer tips for both magnetostrictive and piezo technologies have opened the world of ultrasonics. The thinner the tip, the greater the patient comfort from the standpoint of tissue distension and vibration. Thin tips should be operated on low to medium power levels to prevent breakage. In addition, thinner tips, especially when operated in lower power ranges, require less water, which improves visual acuity and decreases the potential for gagging.
The shape or configuration of the tip dictates how and where it will be used. A thorough review and understanding of complex root anatomies will help with the selection of the proper insert tip. Most inserts can be used in any machine with compatible technology; however, some inserts work only in specific units.
Universal straight tips are the most popular and come in a number of diameters, from extremely thick to a diameter similar to an 11/12 periodontal explorer. Universal tips are as the name implies, adaptable to many clinical challenges. Most clinicians begin ultrasonic scaling using universal inserts.
Right and left configurations have a specific bend in the tip that improves access in complex areas such as furcations, malpositioned teeth, orthodontic appliances, periodontal splinting, or teeth in lingual-version. Beaver-tail inserts are appropriate for effective initial gross deposit disruption, but should be followed by instrumentation with more slender tips. The triple bend configuration is an excellent design for patients with heavy stain.
Specialty tips are available for use around implants in both magnetostrictive and piezo electric formats. In addition, some manufacturers have created diamond-coated inserts, which are specifically for surgical procedures or removing burnished residual calculus. To date there is no industry-wide standard for the grit diameter of diamond-coated inserts, which have the potential for removing irreplaceable tooth structure much more quickly than a standard insert. Given the potential for long-term damage, diamond-coated tips should be limited to open flap surgical procedures or in conjunction with periodontal endoscopy.
There are many more tip designs for piezo electric units than magnetostrictive scalers. This is a bonus when accessing complex root anatomy or instrumenting areas with compromised access, especially since piezo technology favors the use of the lateral tip surfaces.
All ultrasonic scalers have a power control knob to control the insert’s amplitude setting. Again, there is no industry-wide standard for a particular power level. This means power levels on different machines cannot be directly compared and require the individual experience of the clinician. Low power settings are perfect for deplaquing or removal of light calculus and stains. A mid-range setting is appropriate for disrupting more extensive deposits. Thinner inserts perform very effectively on low to medium powers, and are prone to break if the amplitude is set too high. The highest power settings should be reserved for dense, tenacious deposits. Only the most robust tips are designed to operate at high power levels.
Disrupting the Biofilm
The goal is to disrupt biofilm and remove hard deposits and surface stains. Small bubbles form as the fluid irrigant travels down the length of the vibrating tip, creating cavitation. The turbulent bubble-filled fluid travels outward, a process called acoustic microstreaming. Biofilm destruction begins as the microscopic shock waves from the imploding bubbles create fluid turbulence that shears the sticky biofilm from its mooring. The destructive forces of the cavitated fluid coupled with the overlapping strokes of the vibrating tip dislodge both hard and soft deposits.
At times we can see gooey biofilm bubbling up out of the sulcus. Other times the fluid irrigant runs cloudy with particles of pulverized calculus, or we can see big chunks of debris right after we’ve instrumented an area. Occasionally there is no visible debris, but post-scaling evaluation reveals a newly smoothed tooth surface.
Debridement takes time regardless of the methodology. A common misconception is the time it takes to fully instrument a surface with an ultrasonic scaler. Initially it may take as much time as hand instrumentation simply because more areas are now accessible with the slimmest tip. Sometimes the biofilm mass can be very resistant to removal. Some deposits are particularly difficult to remove and require time and perhaps many different inserts.
If you are expecting one quick swipe through the sulcus on every patient, please reconsider what you expect from ultrasonic scalers. There is a certain amount of finesse required in ultrasonic scaling. It is certainly not a drive-by technique that allows one to treat twice as many patients. Consider what we have learned from power toothbrushes that use fluid dynamics. We know that a certain amount of time and skill are required to disrupt biofilm with these brushes. In essence, we need to slow down and give our power scalers time to destroy the enemy.
Since most clinicians do not have the benefit of evaluating their work directly with a periodontal endoscope, it is nearly impossible to determine the exact time it takes to disrupt biofilm, but it is important to cover the entire tooth surface with the surface of an activated ultrasonic insert. Avoid using the insert tip, which can result in inadvertent damage to valuable tooth structure. Ideally, the goal is complete biofilm destruction, and how the tissue resolves gives us clues to the success of our instrumentation. Phase contrast microscopes and other types of microbial testing can also shed light on continued microbial activity.
Magnetostrictive units should be separated into automatic and manually tuned. The analogy is comparable to cars with manual transmissions versus automatic transmissions. Some ultrasonic scalers allow clinicians to switch between automatic and manual modes. Manually tuned magnetostrictive scalers allow clinicians to customize the scaling experience via a separate frequency control knob so the tip movement correlates more closely to the actual clinical challenge. This is accomplished by tuning the tip out of phase, which produces a softer vibration that requires less fluid irrigant.
Learning to use a manually tuned unit is reminiscent of learning to drive a car with a manual transmission. At the beginning, there is a greater learning curve. Learning to tune an insert out of phase is easy but takes practice. Gaining this skill, coupled with the right equipment, literally puts one in the driver’s seat.
In other words, a properly used manually tuned unit allows one to customize ultrasonic scaling for each specific tooth surface. This refinement in technology gives practitioners a broader range of clinical applications because of the precise control over the tip movement, as well as the ability to use micro-fine tips.
Even patients with hypersensitive roots can be comfortable with a manually tuned unit. In addition, little to no anesthesia is required for a procedure, which is particularly important for the growing number of medically complex patients who should avoid anesthesia as much as possible.
Ultrasonic scaling, once considered the lazy way to remove calculus, is capturing the attention of clinicians everywhere. Our education encourages excellence. We want to perform clinical procedures at a high level without risking a life full of cumulative trauma disorders. Contemporary ultrasonic scalers allow us to achieve both goals and remain in the comfort zone.
About the Author
Anne Nugent Guignon, RDH, MPH, is the senior consulting editor for RDH magazine. She is an international speaker who has published numerous articles and authored several textbook chapters. Her popular programs include ergonomics, patient comfort, burnout, microultrasonic scaling, and advanced diagnostics and therapeutics. Recipient of the 2004 Mentor of the Year Award, Anne is an ADHA member and has practiced clinical dental hygiene in Houston, Texas, since 1971. You can reach her at [email protected] or (832) 971-4540, and her Web site is www.anneguignon.com.
Techniques For Increasing Scaling Effectiveness
- Activate insert before placing on tooth surface
- A light touch improves debridement potential
- Heavy pressure dampens precious ultrasonic vibrations
- A light touch heightens tactile sensitivity
- Light pressure on the insert increases patient comfort
- Keep the vibrating insert moving
- Use fluid, erasure-like movements
- Keep the insert in continuous contact with the tooth surface
- Keep the insert surface as parallel to the tooth as possible
- Instrument all surfaces with multiple, overlapping strokes
- Open the angle slightly around cosmetic restoration margins
- Lower power settings to improve tactile sensitivity
- Decrease the power setting or tune out of phase to create more gentle vibrations