In today's sophisticated practice settings, ultrasonic dental equipment is routinely incorporated unless contraindications prevail. Its use in oral prophylaxis, nonsurgical periodontal therapy, and periodontal maintenance provides many potential advantages. Like hand instrumentation, however, the risk of overinstrumentation is possible with ultrasonic technology.
Overinstrumentation is a clinician-created or iatrogenic problem stemming from the use of improper technique or debriding more than is necessary to encourage healing of adjacent tissues. Overinstrumentation can include creating root defects, leaving roughness, and removing unnecessary tooth structure—each of which may encourage biofilm accumulation and tooth sensitivity. A smooth root or implant surface reduces the likelihood that plaque biofilms will reattach and, thus, may decrease the risk of periodontal diseases, peri-mucositis, and peri-implantitis.
The goal of debridement is to remove plaque biofilms, their byproducts, their retentive factors, and calculus-embedded cementum to create a biologically acceptable root surface conducive to optimal healing, while preventing unnecessary loss of tooth surface. As such, the point of overinstrumentation may be different for each patient. During nonsurgical periodontal therapy, the patient's response to individualized therapy is evaluated throughout multiple appointments and at the reevaluation visit. At these times, additional instrumentation may be indicated due to tactile interpretation, bleeding points, visible inflammation, or endoscopic observation of calculus. This therapy is justified and is not considered overinstrumentation.
RELEVANT RESEARCH
Researchers continue to investigate the causes of root defects, roughness, and unnecessary tooth surface removal with mechanical root debridement. In regard to root defects, power setting, load of the ultrasonic insert/tip (UIT) on the tooth, and the cross-sectional shape of UITs may affect dentin defects with both magnetostrictive and piezoelectric ultrasonic technology. Casarin et al1 found that hand and ultrasonic instrumentation produced the same level of defect depths, regardless of power settings. As both power and manual instrumentation create alterations in the dentin surfaces under the best of conditions, optimal outcomes are achieved by using proper instrumentation technique.
The amount of root roughness remaining after instrumentation has also been examined. Singh et al8 concluded that manual and ultrasonic instrumentation methods were equal in debridement efficacy, while other studies revealed that ultrasonic instrumentation left a smoother surface than curets. Marda et a found that magnetostrictive inserts created reduced root surface roughness, less root surface removal, and better efficiency of calculus removal than a rotary bur or curets.
Yousefimanesh et al10 concluded that the exertion of different lateral forces in both magnetostrictive and piezoelectric devices caused similar effects on tooth surfaces. In this in vitro study, root surface roughness was the same after both types of ultrasonic technology were used, though the piezoelectric device produced the least roughness when 200 g of pressure were applied. When piezoelectric, magnetostrictive, and curet instrumentation was compared, each removed approximately the same amount of calculus.7 Instrumentation with curets, however, produced the roughest surface. Kawashima et al reported that ultrasonic instrumentation methods produced a smoother surface than the curet, and that there was a difference in root surface roughness after two different piezoelectric tips were used.
Results of such studies are not directly comparable, however, due to the various methodologies employed. Clinicians are encouraged, nevertheless, to heed recommendations regarding prevention of overinstrumentation due to its negative effects on clinical outcomes.
Additional research has been performed on the effect of coated UITs designed for root surfaces and implants. Vastardis et al found that diamond-coated UITs left a rougher root surface and removed more root surface compared to hand instruments and a nondiamond-coated UIT, with the nondiamond-coated UIT producing the smoothest root surface. In a study by Ribeiro et al, results showed that a sonic diamond-coated tip and a standard UIT produced more roughness than a curet. The use of diamond-coated UITs without an endoscope or outside of surgical intervention is not recommended because of the likelihood for overinstrumentation. Additional studies evaluating which coatings produce the least amount of roughness after instrumentation are ongoing.
In regard to root surface removal, Mishra and Prakash6 compared laser therapy to ultrasonic and hand instrumentation using extracted teeth. Ultrasonic instrumentation yielded surfaces devoid of deposits and root surfaces that were essentially unchanged. Hand instrumentation removed more root surface than other methods, however, the surfaces were smooth.The laser provided similar outcomes in calculus removal as both ultrasonic and hand instrumentation, but it also caused greater loss of tooth surface and left more surface roughness than the other techniques. Santos et al demonstrated that curets removed more root surface tissue than an ultrasonic device. These data support the benefits of ultrasonic dental supplies in removing the least amount of root surface while achieving the desired clinical outcome.
Dental hygienists must understand the five aspects of quality ultrasonic therapy in order to prevent overinstrumentation. These factors include: power setting, tip angulation, lateral pressure, exposure time, and tip wear . The interaction of one or more of these factors results in the increased probability of overinstrumentation.
