Sonic and ultrasonic scalers in periodontal treatment: a review

Bio-effects and safety of low-intensity, low-frequency ultrasonic exposure

Low-frequency (LF) ultrasound (20-100 kHz) has a diverse set of industrial and medical applications. In fact, high power industrial applications of ultrasound mainly occupy this frequency range. This range is also used for various therapeutic medical applications including sonophoresis (ultrasonic transdermal drug delivery), dentistry, eye surgery, body contouring, the breaking of kidney stones and eliminating blood clots. While emerging LF applications such as ultrasonic drug delivery continue to be developed and undergo translation for human use, significant gaps exist in the coverage of safety standards for this frequency range. Accordingly, the need to understand the biological effects of LF ultrasound is becoming more important. This paper presents a broad overview of bio-effects and safety of LF ultrasound as an aid to minimize and control the risk of these effects. Its particular focus is at low intensities where bio-effects are initially observed. To generate a clear perspective of hazards in LF exposure, the mechanisms of bio-effects and the main differences in action at low and high frequencies are investigated and a survey of harmful effects of LF ultrasound at low intensities is presented. Mechanical and thermal indices are widely used in high frequency diagnostic applications as a means of indicating safety of ultrasonic exposure. The direct application of these indices at low frequencies needs careful investigation. In this work, using numerical simulations based on the mathematical and physical rationale behind the indices at high frequencies, it is observed that while thermal index (TI) can be used directly in the LF range, mechanical index (MI) seems to become less reliable at lower frequencies. Accordingly, an improved formulation for the MI is proposed for frequencies below 500 kHz.

The use of a disclosing agent during resective periodontal surgery for improved removal of biofilm

A total removal of the bacterial deposits is one of the main challenges of periodontal therapy. A surgical approach is sometimes required in order to allow a correct access to the areas not thoroughly reached during the initial therapy. The present study focuses on the surgical scaling effectiveness in root deposits removal; the potential support of a disclosing agent during this procedure is also evaluated. Forty surgical periodontal patients were randomly divided between surgeries where the operator was informed about a final examination of the residual root deposits and surgeries where the operator was not informed. Straight after scaling procedures a supervisor recorded the O'Leary Plaque Index of the exposed roots by mean of a disclosing agent and the percentage of teeth with residual biofilm. After the stained deposits removal, a second chromatic examination was performed and new data were collected. Mann-Whitney U-test and Wilcoxon test for paired samples were used for comparisons respectively between the two surgery groups and the first and the second chromatic examination; one-sided p-value was set at 0.05. At first examination no significant differences between the two groups were observed regarding Plaque Index (p=0.24) and percentages of teeth with residual biofilm (p=0.07). The 100% removal of roots deposits was never achieved during the study but a significant reduction of 80% of root deposits was observed between first and second examination (p=0.0001). Since root deposits removal during periodontal surgery resulted always suboptimal, the use of a disclosing agent during this procedure could be a useful and practical aid.

Non-surgical periodontal therapy assisted by potassium-titanyl-phosphate laser: a pilot study

As the American Academy of Periodontology indicates, the treatment of chronic periodontitis should be achieved in the least invasive manner through non-surgical periodontal therapy. However, complete removal of subgingival plaque and calculus is hindered with increasing probing depth (PD) and furcation involvement using hand, sonic or ultrasonic instruments. Many authors have suggested that the use of laser as an adjunct to scaling and root planing (SRP) might improve the effectiveness of conventional periodontal treatment. The aim of this study was to evaluate potassium-titanyl-phosphate (KTP) laser in non-surgical periodontal therapy. Seven hundred and thirty sites with probing depths of 4-6 mm were involved in the study. The sites were divided into four groups: control (SRP, chlorhexidine gel 0.5%), group A (SRP, chlorhexidine gel 0.5%, three sessions of KTP laser irradiation); group B (SRP, three sessions of KTP laser irradiation) and group C (SRP, irrigation with povidone-iodine 10%, three sessions of KTP laser irradiation). KTP laser was used with the following parameters: output power 0.6 W, time on 10 ms, time off 50 ms, 30 s per irradiation, fluence 19 J/cm(2). All the sites showed improvement in all clinical parameters. Clinical attachment loss (CAL), pocket probing depths (PPDs) and bleeding on probing (BOP), especially in the lased groups, showed significant results (P < 0.001). Our experience showed KTP laser to be a significant help in SRP; nevertheless, more studies are necessary to confirm our results.