Sonic vs. Ultrasonic Scalers

About ten years ago, a colleague called me to ask what type of ultrasonic scalers (piezoelectric or magnetostrictive scalers) did I prefer for periodontal care. He was getting ready to purchase units for all of his operatories. I told him that in my opinion, it really did not matter which system he selected. At the time, ultrasonic scalers were primarily used for gross calculus debridement, while curettes were used for the finer aspects of root planing. I told him what mattered most was the time spent per tooth and the skill of the operator in using their particular instrumentation.

Only a few things have changed since then. Last year, the American Academy of Periodontology published a position in paper summarizing what is known about these instruments and how they compare in their effectiveness (J. Periodontol 2000:71;1792-1801). Recent modifications of tip design for power driven scalers provide improved access into deep pockets and difficult to reach areas such as furcations. Therefore, studies were undertaken to shed light on the potential roles of sonic and ultrasonic scalers in periodontal therapy.

Basically, there are two types of power driven scalers. Sonic scalers are powered by compressed air and operate at lower frequencies which range between 3000 to 8000 cycles per second. An example of this type of scaler is the Star Titan sonic scaler. Ultrasonic scalers are divided into two types. Magnetostrictive ultrasonic scalers operate between 18000 and 45000 cycles per second. An example of this type is The Cavitron. The movement is generated by passing an electrical current over a stack of metal strips or a metal rod which is attached to the scaler's tip. The tip movement can be linear or eliptical and all surfaces are active while in use. Piezoelectric units operate between 25000 to 50000 cycles per second. Movement is generated by electricity passing over crystals housed in the handpiece. The tip movement is generally linear and allows two sides of the tip to be active. These differences in the type of movement can generate different root surface alterations following debridement.

Clinical Comparisons- What really matters most is whether or not there are are different clinical outcomes depending upon the type of instrumentation selected. In comparing sonic, piezoelectric and magnetostrictive scalers, studies have shown nearly equivalent clinical results in spite of the differences of frequencies, tip movement, and root surface characters following planing. When comparing powered scalers vs handed instrumentation, again similar reductions in probing depth and bleeding up on probing all are achieved. After reviewing all available data, it was concluded that improvements in clinical parameters are nearly equal for all types of mechanical instruments as long as sufficient time is spent to thoroughly debride the roots. However, powered scalers do have some advantages over hand instrumentation.

Plaque Removal- Studies confirm that plaque removal can be equivalently accomplished by powered driven or hand instruments. However, the lavage effect, which provides a constant flushing of the periodontal pocket during instrumentation appears to have some improved therapeutic effects. The lavage effect coupled with the cavitation and microstreaming improve the dislodgement of plaque slightly beyond the reach of the instrument tip. (a negative consequence of this is the notable generation of contaminated aerosols. Proper infection control procedures must be in place).

Endotoxin and cementum removal- It was previously thought that endotoxin was embedded and firmly bound to cementum. Therefore, to render the root biologically compatible extensive cementum removal was required to eliminate the endotoxins. Currently, it is known that endotoxin is a superficially associated surface substance which is easily removed. Complete cementum removal is not a goal of periodontal therapy. Therefore the extensive root planing to remove altered cementum of the past is not necessary to achieve periodontal healing.

Access to furcations- furcations present some of the most difficult locations to debride. Ultrasonics have proven to be clinically superior in the treatment of class II and class III furcations. New tip designs that are .55 mm in diameter have of become the choice instruments for these areas.

Efficiency- power driven scalers can increase operator efficiency. Several studies have shown that debridement time spent per tooth is reduced when powered driven scalers are used compared to hand instruments. Hand fatigue is significantly reduced since powered driven scalers are used with a lighter touch.

Summary- "Ultrasonic and sonic scalers appear to attain similar results as hand instruments for removing plaque, calculus and endotoxin. Ultrasonics used at medium power seem to produce less surface damage than hand or sonic scalers. Due to instrument width, power driven scaler tips seem to be more effective in furcations." What matters most is the time spent per tooth and mastery of your particular debridement system.