The Right Moves

Excellence in ultrasonic debridement hinges on several elements, one of which is stroke activation.¹ Clinicians can have the best equipment, appropriate power setting, and effective ultrasonic insert/tip (UIT) access and adaptation, as well as recognize the importance of UIT selection and instrumentation sequence, but if their activation technique is faulty, the therapy will fail.

Activation refers to the movement of the UIT across the root surface and the track of coverage that results from the clinician’s technique. Similar to the importance of overlapping strokes when using bladed hand instruments, effective ultrasonic instrumentation requires comprehensive coverage of root surfaces^2,3—a practice that can be easily compromised with indiscriminate movement of the UIT.

DELIBERATE AND METHODICAL

Ultrasonic instrumentation is generally introduced with an emphasis on keeping the UIT moving at all times in order to prevent damage to the tooth surface—particularly the roots, which are more vulnerable to structural and thermal damage.^4,5 The concept of “continual movement” in the mind of a novice clinician can be misconstrued as fast, erratic movement that has no direction (Figure 1).

To prevent this error, focus on the two separate components of the activation stroke—the speed and pattern of the movement. Speed is the number of millimeters per second that the UIT travels. Pattern refers to the tracks of physical contact between the UIT and the root surface—a very narrow path of 1 mm to 2 mm due to the lack of conformation between the side or edge of the UIT and the fluctuating contours of root surfaces.^6,7 Stroke track is frequently misunderstood in ultrasonic instrumentation.

The assumption is that each stroke covers a broad surface area, leading clinicians to believe they have adequately treated the root when they have only just begun (Figure 2). Take note of these elements during ultrasonic debridement, visualizing the limited path of contact and the speed at which handpiece movement occurs. Would the entire subgingival surface area be covered with this technique? Clinicians experienced in dental endoscopy can attest to the necessity of using overlapping strokes to achieve comprehensive coverage of root surfaces, whether the deposit is calculus or biofilm.⁸ Only those limited portions of root surface that have been physically contacted by the tip can be considered adequately treated.⁹

Disciplined stroke activation that is deliberate and methodical, as opposed to haphazard, can help ensure adequate coverage. One method is to work in vertical channels that circumnavigate the tooth. Begin each channel at the coronal edge and move apically with overlapping horizontal and oblique strokes within the channel until the soft tissue attachment is reached, then proceed to the next channel (Figure 3 to Figure 5).

The relative speed of UIT movement across the surface should coincide with the degree of mineralization in tooth deposits. Hard or tenacious subgingival calculus should be instrumented with slow, deliberate movement approximating 3 mm to 5 mm per second. Begin at the outermost edge of the deposit using the tip of the UIT to fracture the bulk of the deposit, and follow with slow, sweeping strokes.³ The purpose of this technique is to permit adequate energy transfer to the deposit for clean removal. A common but incorrect approach moves the UIT across the broad span of the entire deposit, reducing its bulk layer by layer, which can result in burnishing.

FULL MOUTH DEBRIDEMENT

Patients presenting with moderate to heavy deposits that cannot be completed in one appointment often receive initial or gross full mouth debridement (FMD)—a similar approach that essentially does a “once over” across all surfaces at a rapid speed of activation. The outermost layer of calculus is briefly touched upon rather than removed, a process that makes detection and removal difficult when the patient returns for more definitive therapy. The free gingival collar will shrink in response to FMD, compromising access to the base of periodontal pockets where calculus remains. Additionally, the presence of Gram-negative periodontal pathogens below a tightened gingival margin is the prime environment for abscess formation.¹⁰

The FMD approach is also troublesome because it may lead patients to question the need for additional treatment once they think their inflammation has dramatically subsided following initial or gross debridement, and they may decide not to return at all. Root surfaces that have been partially scaled further complicate treatment. When burnished calculus is left behind, the disease process goes underground to where overt signs and symptoms, previously evident to the patient before FMD, are now imperceptible.¹¹

There are no shortcuts to effective scaling and root planing, regardless of whether hand or ultrasonic instrumentation is used. During power scaling, clinicians must remember that it is the mechanical action of the UIT in direct physical contact with the deposits on root surfaces that disrupts calculus and biofilm, which can then be flushed away by the ultrasonic scaler’s water coolant supply.^12–14

TREATMENT PLANNING

Proper treatment planning can guard against errors of hasty or careless debridement. When time is limited, use a segmental approach for patients with calculus, so that definitive therapy (scaling to completion) can be accomplished within the timeframe available. Use slow, controlled movements to activate overlapping strokes that cleanly remove all root accretions. Definitive periodontal debridement in limited segments provides patients with an awareness of which areas are healthy vs those that are inflamed.

The contrast between the areas treated and those not yet instrumented provides incentive to continue with therapy. Patients presenting with biofilm only can be treated using activation strokes at a more rapid pace than what is needed for calculus removal. In either case, the key to success is comprehensive coverage. Disciplined movement of the ultrasonic handpiece while considering its speed and pattern of motion in a segmental approach sets the stage for more predictable and improved clinical results. Diligence and skillful technique in stroke activation to ensure every square millimeter of subgingival surface has been thoroughly instrumented will support successful therapeutic outcomes.

REFERENCES

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12. Baehni P, Thilo B, Chapuis B, Pernet D. Effects of ultrasonic and sonic scalers on dental plaque microflora in vitro and in vivo. J Clin Periodontol.1992;19:455–459.
13. Nosal G, Scheidt MJ, O’Neal R, Van Dyke TE. The penetration of lavage solution into the periodontal pocket during ultrasonic instrumentation. J Periodontol. 1991;62:554–557.
14. Schenk G, Flemmig TF, Lob S, Ruckdeschel G, Hickel R. Lack of antimicrobial effect on periodontopathic bacteria by ultrasonic and sonic scalers in vitro. J Clin Periodontol. 2000;27:116–119.

From Dimensions of Dental Hygiene. April 2013; 11(4): 26–28.