The literature is clear that periodontal therapies aimed at altering the progression of inflammatory periodontal diseases must include meticulous subgingival mechanical débridement during both the nonsurgical and the surgical phases of treatment as the basis of most anti-infective therapy. In the past, infection control was achieved by the mechanical removal of subgingival deposits of plaque, calculus, and endotoxin with curets, files, and hoes. Historically, it was also generally agreed that aggressive scaling and root planing with hand instruments was necessary to remove tenacious calculus deposits to produce roots as smooth as possible for removal of the endotoxins previously thought to be deeply embedded into the root surfaces. Based on current evidence in the literature, it is now known that endotoxin is a weakly adherent surface phenomenon and that sonic and ultrasonic (power-driven) instruments can be used to accomplish definitive root detoxification and maximal wound healing without overinstrumentation of root and without extensive cementum removal.

Power-driven scalers may have unique advantages because of the cavitational activity associated with ultrasonics thought to supplement removal of root surface plaques. In addition, the constant flushing activity of the lavage used to cool the tips results in disruption of the unattached and weakly attached subgingival plaques.^{58, 59} The ability to flush the pocket during subgingival instrumentation with water or other chemical irrigating solutions is unique to ultrasonic and sonic scalers and has been shown to enhance pocket depth reduction and gain in clinical attachment beyond that achieved with hand scaling.^{10, 24, 45} The added benefit of chemical lavage during ultrasonic instrumentation shows great promise and may enhance the overall effect of nonsurgical anti-infective periodontal therapy.

Other major advantages of power-driven scalers may include better access to difficult areas, such as deep narrow defects, root grooves, and furcations, using newly designed microultrasonic tips, which are smaller in diameter and able to penetrate the pocket approximately 1 mm farther than hand instruments.^{16, 53} Taken together, it appears that use of ultrasonic or sonic scalers for periodontal debridement will result in improvements in clinical and microbial parameters at a level equal to or superior to hand scalers.