Written by Cynthia Hughes, RDH, BS, MEd Monday, 31 December 2007 19:00
Originally developed for use in operative dentistry, ultrasonic devices have been around since the 1950s. Initially used for cavity preparation and the removal of decay, their use in restorative dentistry diminished after the appearance of high-speed handpieces. Ultrasonic scalers—which came onto the market in the late 1950s—were used for removal of heavy calculus and extrinsic stains. Their popularity grew during the 1960s and 1970s, although limited insert tip designs restricted ultrasonic scaling to mainly the removal of heavy supragingival deposits—“gross scaling.” The hygienist who used the ultrasonic scaler for more than gross deposit removal was often considered lazy by colleagues.
During the 1980s, manufacturers introduced thinner, probe-like ultrasonic tips which lent themselves to removal of deposits below the gum line. Curved tips were also marketed, allowing the clinician access to deep periodontal pockets and furcation areas. During this same era, research surfaced indicating debris removal using ultrasonics was equally as effective as with hand scaling. This paradigm shift led to a viable treatment modality for nonsurgical periodontal therapy—and for redemption of those clinicians who had fully embraced ultrasonic scaling.
Contemporary dental hygienists are thoroughly educated in the use of a variety of power-driven scalers, ranging from sonic to ultrasonic. Students are often introduced to these power machines early in their clinical education rather than as an adjunct just prior to graduation. Clinical textbooks include entire sections on power-scaling technique and patient selection. This article will briefly review different types of power scalers, proper usage of the magnetostrictive ultrasonic scaler, and patient/clinician safety considerations.
SONIC VERSUS ULTRASONIC
Clinicians often refer to any power-driven scaler as an ultrasonic. However, the savvy clinician will know the differences in these machines and select the appropriate device for the individual patient’s needs. Both sonic and ultrasonic scalers utilize rapidly vibrating, water-cooled tips to remove de-posits from the tooth surface and to debride the periodontal pocket. The vibration of the insert tip is measured as frequency. The sonic scaler operates in a frequency range of 2,500 to 7,000 cycles per second.
A sonic unit attaches to conventional high-speed handpiece tubing. The unit is small and portable since a separate power unit is not needed. Compressed air blows over a metal rod in the unit, which pulsates and causes the tip to vibrate in an orbital pattern. Water flows through the unit to dissipate heat that builds up from the pulsating rod. As the frequency range of the sonic scaler is extremely low, it is difficult to remove tenacious deposits with this type scaler.
Ultrasonic units operate between 20,000 and 50,000 cycles per second. The 2 types of ultrasonic units currently on the market are the piezoelectric and the magnetostrictive. These units have been shown to be effective in deposit removal and, with their variety of tip-styles, are excellent devices for nonsurgical periodontal therapy.
The handpiece of piezoelectric devices contains ceramic crystals which change size as electrical current is passed over them. This size change results in a linear motion of the unit’s tip. Although water flows through the unit, little heat is produced by the movement of the crystals or tip.
The magnetostrictive ultrasonic unit functions at a frequency just slightly lower than the piezoelectric model. This scaler’s handpiece contains a stack of metal strips or a metal rod which shortens and lengthens when exposed to an electromagnetic field. This shortening/lengthening process causes an elliptical movement of the tip. Heat is generated by the electrical-to-mechanical energy shift; therefore, water-cooling is necessary. Water flows through the handpiece, providing the needed cooling plus the added benefit of lavage, or flushing of the periodontal pocket.
PROPER USAGE OF THE MAGNETOSTRICTIVE ULTRASONIC
Proper usage and maintenance of the magnetostrictive ultrasonic scaler is imperative for effective patient care and longevity of the machine. Clinicians should familiarize themselves with the manufacturer’s recommendations for whichever unit he/she is using. As most hygienists “inherit” a power scaler when joining a new dental practice, time spent investigating the type machine and its correct usage is time well spent.
Ultrasonic scaler inserts come in a variety of sizes and configurations. Each insert will include the following features:
• insert tip,
• water outlet,
• handle grip,
• o-ring seal,
• connecting body, and
• magnetostrictive transducer (metal stack or rod).
All surfaces of the magnetostrictive tip are active during use. However, energy dispersion varies depending on the surface being utilized. The extreme point of the insert tip is the most powerful (Figure 1). The concave, inner side of the tip is next most powerful, followed by the convex back of the tip. The lateral sides of the insert tip are least powerful—and therefore least effective for hard deposit removal.
All ultrasonic scalers utilize flowing water. The water line should be flushed with the handpiece held horizontally—and no tip inserted—for 2 minutes prior to using the instrument. This will dislodge biofilm that has collected in the water lines. The handpiece should then be held vertically and filled with water. This will expel any air bubbles in the line, thereby decreasing the heat buildup around the metal stacks of the tip. With the handpiece full of water, the appropriate tip should be dropped in and gently snapped into place. The handpiece should be refilled with water each time a different insert is placed into it.
Water may flow from the tip through an opening in the tip itself or through an external port. External placement of the water port allows use of a thinner, more probe-like tip. Caution must be used when handling an insert with an external water port to prevent dislocation of or damage to the water tube, thus rendering the tip ineffective (Figure 2). Likewise, the clinician must use care when cleaning and handling the metal stacks of the insert. The metal stacks will become soft during autoclave sterilization. Wrapped inserts should be placed flat in the autoclave with no other items resting on top of them.
TIP SELECTION AND ACTIVATION
Figure 1. Point of insert tip.
Figure 2. External water port.
Figure 3. Near 0° angulation.
Figure 4. Improper tip placement.
Figure 5. Left, right, and straight tips.
A variety of insert tips are available for clinicians. Light-weight handles, extended length tips, area specific curves, and furcation instruments are only a few of the features contemporary manufacturers have to offer. The hygienist must determine the objective for each patient’s therapy prior to selecting a tip for usage. Is the procedure for the removal of heavy, supragingival debris? A heavier tip with an internal water port may be called for. Is the hygienist scaling teeth with furcation involvement? A furcation-ball tip with an external water port might be used. Is the appointment for removal of biofilm? The lateral surface of a universal perio tip would do the trick.
Magnetostrictive ultrasonic insert tips are active on all sides. The clinician can develop an instrumentation technique using the various surfaces to meet the clinical situation. Appropriate tip placement on the tooth is imperative for debris removal and prevention of damage to hard tissue surfaces. The shank of the insert tip should be placed parallel to the long axis of the tooth with little to no angulation (Figure 3). The tip should never be directed towards the tooth at a 90° angle (Figure 4). Only a light, lateral pressure is needed to activate a stroke. In fact, applying pressure against the tooth with the tip (similar to the working stroke used with hand scalers) actually slows the speed of the tip and could potentially damage the tooth surface. A combination of stroke patterns is needed to completely debride the tooth. Vertical, horizontal, and oblique strokes can all be used to access both supra- and subgingival areas. The tip must be kept moving at all times in order to prevent heat buildup and possible damage to the tooth. Short, overlapping strokes—similar to an erasing motion—will ensure complete deposit removal. The tip does not need to be placed completely under the calculus. Approaching the deposit from any edge will fracture the deposit and erase it from the tooth’s surface. The clinician must be patient, letting the ultrasonic insert tip do the work.
In order to maximize time and efficiency, the hygienist should develop a sequence for ultrasonic scaling based on the patient’s hygiene treatment plan. A systematic approach designed to remove the most debris—with as few tip changes as possible—should be used. The clinician should begin with a standard/universal insert for heavy supragingival and shallow subgingival deposits, followed by thin, perio inserts for light-to-moderate and subgingival deposits. All areas should be instrumented with the universal instrument tip prior to changing to a perio or left/right tip.
While universal—or straight—tips are effective on all accessible tooth surfaces, they are most effective on buccal and lingual surfaces of all teeth and interproximal surfaces of anterior teeth. Curved tips—facing either left or right—are most effective on interproximal surfaces of posterior teeth, in furcations, around malpositioned molars, and on concave surfaces. The term left and right tip refers only to the direction of curvature of the insert tip, not to a location for use in the mouth (Figure 5).
The ultrasonic handpiece should be grasped with a light pen grasp, similar to that used with a periodontal probe. A light grasp will increase tactile sense of hard deposits and tooth topography, decrease clinician fatigue, and increase patient comfort. A lightweight handpiece is recommended to reduce the potential of repetitive stress trauma to the hygienist’s hand. Some manufacturers offer an insert with a swivel design to add increased comfort and ease of use. An intra- or extraoral fulcrum is needed to maintain proper control of the ultrasonic handpiece during activation. This encourages a smooth, controlled motion of the tip and promotes the light pressure needed for debris removal.
As with any clinical care given, the clinician should consider his own personal safety as well as that of his patient. Standard precautions should be used when using an ultrasonic scaler. Personal Protective Equipment (PPE) should include eye coverings (for clinician and patient), an efficient mask, and lastly, gloves. A plastic drape over the patient’s clothing is always a thoughtful touch.
A thorough review of the patient’s medical history should be performed prior to providing treatment with a power scaler. Researchers once recommended avoiding the use of magnestostrictive ultrasonics on patients with an unshielded pacemaker. More contemporary pacemakers are shielded and theoretically should not be harmed by the ultrasonic waves. However, always err on the side of caution: check with the patient’s cardiologist!
Patients with communicable diseases, difficulty swallowing, or who are prone to gagging are not good candidates for ultrasonic scaling. Additionally, those patients who are medically compromised should be given additional consideration. Always check current scientific literature and/or the patient’s physician for guidelines.
When using ultrasonic instrumentation around implants, care must be taken to avoid damaging the abutment and prostheses. Protective plastic sheaths are available to cover the insert tip during implant care. Cosmetic restorations can also be damaged by inappropriate ultrasonic tip usage. Areas of demineralization can suffer further breakdown from the rapid vibrations caused by power scalers. The clinician must perform a thorough assessment of the patient’s oral cavity to identify any materials or demineralized areas that could be damaged prior to beginning the powerscaling process.
MORE POWER TO YOU!
The contemporary dental hygienist’s armamentarium would be seriously deficient without a power-scaling device. Literature has shown that power scalers are equally as effective as hand scaling for debris removal. Both the patient and the clinician benefit from the efficient deposit removal provided by ultrasonic scalers.
Hygienists should explore each type of power scaler to find the machine that works best for patients. Trade shows are opportune locations to compare styles, brands, and different types of inserts. Try sonic, piezoelectric, and magnetostrictive scalers. Additionally, this author recommends a hands-on course for more seasoned hygienists in order to update both knowledge and skill level.
Select an appropriate power machine…and happy scaling!
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