Perio Reports provides easy-to-read research summaries on topics of specific interest to clinicians. Perio Reports research summaries will be included each month to keep you on the cutting edge of dental hygiene science.

Classic Study
A quick look at how power scalers work

Ultrasonic instruments work by converting high frequency electrical current into mechanical vibrations above 20,000 cycles per second. Two types of ultrasonic units are available: magnetostrictive and piezoelectric. Both types have a generator that produces a high frequency electrical current; both require water for cooling. Where they vary lies in the way the electrical energy is converted into mechanical vibrations.

The magnetostrictive transducer utilizes either a stack of flat metal strips (the Cavitron is an example), or a rod of ferromagnetic (capable of being magnetized) material (e.g., the Odontoson M). This magnetostrictive transducer is connected to the working tip to form a handpiece insert. Contained within the handpiece is a coil. When the electrical current is turned on, the coil within the handpiece becomes magnetized. The stack or transducer portion of the handpiece insert reacts to the magnetic field by expanding and contracting in accordance with the alternating current. This rapid expansion and contraction results in vibrations that are transmitted to the attached working tip. The working motion of the magnetostrictive scaler is generally elliptical.

The piezoelectric transducer does not require magnetostrictive stacks, and is completely contained within the handpiece, rather than being connected to the working tip insert. Alternating electrical current is applied to reactive crystals causing a dimensional change, which is then transmitted to the working tip in the form of ultrasonic vibrations. The working tip is small and easily threaded into the handpiece. The working motion of the piezoelectric scaler is generally linear. An example of this type is the Pro-Select.

Sonic instruments also use vibrations of the working tip, but are mechanical rather than electrical. Vibrations between 2,000 - 6,000 cycles per second are produced by means of air pressure, rather than by electrical energy. An example of their mechanics is found in the Titan Sonic Scaler, in which, the handpiece is composed primarily of a hollow rod, a rotor, and several rubber o-rings. Compressed air is forced through a hollow rod in the handpiece. The rotor is a thin metal ring 6 mm wide, which encircles the hollow rod above a series of 10 scientifically angled holes. As the air passes through the hollow rod, it escapes through the 10 holes and causes the rotor to vibrate, which, in turn, causes the entire rod to vibrate. These vibrations are then transferred to the working tip that is screwed into the hollow rod. The working motion of the sonic scaler is generally elliptical. Water is not required for cooling, but enhances the effect through acoustic streaming and lavage.

Clinical Implications: No superiority in the therapeutic effect between the magnetostrictive, piezoelectric, or sonic scaler has yet been determined by research trials.

Ewen , S., Glickstein, C.: Ultrasonic Therapy in Periodontics, Charles C. Thomas, Publisher, 1968.

Low-level laser used after SRP reduces inflammation

Lasers have been used in dentistry since the 1980s, and much longer in medicine. Oral surgeons use the carbon dioxide laser (CO2) to remove superficial tissue layers. The Er:YAG laser is effective on both hard and soft tissues. It’s been used for calculus removal and during endodontic procedures. Low-level lasers do not cut and are used in conjunction with photodynamic processes.

Cutting lasers require more than one watt of power, compared to low-level lasers functioning in the milliwatt range. Low-level lasers function in the red or near-infrared spectrum of light, and can be used to activate intracellular photoreceptors; triggering a cascade of events beneficial to periodontal healing.

Researchers at the Karolinska Institute in Sweden tested a low-level laser after scaling and root planing (SRP) to determine if a therapeutic benefit was realized. Seventeen patients with moderate periodontal disease participated in this short-term study. All subjects received SRP and oral hygiene instructions at baseline. Each week for six weeks, subjects were treated on one side of the upper arch with an activated laser and on the other side with a laser using only a red LED light. At the end of six weeks, clinical and laboratory results were compared to baseline.

Average baseline probing depths for both laser and control sides were 4.7 mm. Following treatment, average probing scores were 4.5 mm for the control side and 3.8 mm for the laser-treated side. Both gingivitis and plaque scores were lower for the laser-treated teeth compared to control teeth. Gingival crevicular fluid flow was reduced for laser-treated areas and cytokine levels were also lower compared to controls.

Clinical Implications: Low-level lasers may provide a significant role in periodontal therapy provided by dental hygienists.

Qadri, T., Miranda, L., Tunér, J., Gustafsson, A.: The Short-Term Effects of Low-Level Lasers as Adjunct Therapy in the Treatment of Periodontal Inflammation. J Clin Perio 32: 714-719, 2005.

Hygiene treatment reduces periodontal disease after third-molar extraction

Impacted third molars can contribute to periodontal deterioration on the distal of the second molar as intra-bony defects may persist after extraction of the impacted third molars. Typically, no periodontal or hygiene treatment is provided at the time of surgical extraction.

Researchers at the Prince Philip Dental Hospital in Hong Kong compared extractions of impacted wisdom teeth with and without dental hygiene treatment. They evaluated the distal of the second molar to determine residual probing depths, bleeding upon probing, attachment levels, recession, and plaque levels. Study subjects had at least one mandibular impacted third molar with early signs of degeneration around the second molar and a probing depth of more than 5 mm.

The 14 test subjects received ultrasonic instrumentation (EMS Piezon Master 400) on the second molar at the extraction visit, just after the third molar was removed. Patients were instructed in proper oral hygiene and asked to rinse twice daily with chlorhexidine for two weeks. At the suture removal visit, one week later, subjects were instructed to brush the distal of the second molar with an end-tuft brush and chlorhexidine. Subjects were seen every six weeks for plaque removal, oral hygiene review and polishing.

The 16 control subjects received only the surgical extraction and suture removal one week later. All subjects were re-evaluated at the end of six weeks.

Distal probing measurements averaged 2 mm less for the subjects who received instrumentation and oral hygiene instructions compared to the controls. All clinical signs were better for those patients who received dental hygiene care than for those who did not. When asked, half of the control subjects (eight) and only two test subjects reported any pain or discomfort in the last two months of the study.

Clinical Implications: Power scaling followed by good oral hygiene and daily use of chlorhexidine after third molar extractions results in good periodontal health.

Leung, W., Corbet, E., Kan, K., Lo, E., Lui, J.: A Regimen of Systematic Periodontal Care After Removal of Impacted Mandibular Third Molars Manages Periodontal Pockets Associated With the Mandibular Second Molars. J Clin Perio 32: 725-731, 2005.

Incidence of bacteremia not as high as once thought

Bacteremia, which can be measured through blood samples, occurs when live bacteria enter the blood stream. This can happen through tissue manipulation with probing, instrumentation, and even toothbrushing. In some cases, bacteria can be detected in the blood without doing anything in the mouth. Many researchers over the years have attempted to document the incidence of bacteremia following dental treatment. Their studies used various approaches with equally varying findings.

Researchers at the Glasgow Dental Hospital in Scotland assessed both patient and clinician induced bacteremia in patients with moderate to severe, untreated periodontal disease. Two methods were used to measure bacteria: Blood samples were cultured to see if (and which) bacteria could be grown in the lab; and PCR or polymerase chain reaction (customarily used to measure DNA rather than live bacteria) was the second method used. Both tests were done using blood drawn from patients at baseline, following probing, following toothbrushing on another day, and following ultrasonic scaling.

In general, more positive results were evident with the PCR testing. Culturing depends on the ability of each species present to survive and colonize on the culture medium used. In some cases the PCR result was positive, but no bacteria were grown in culture.

The incidence of bacteremia increased with each step. At baseline, 6-9% of patients had positive test results; following probing it was 16-20%; following toothbrushing as the first intervention it was 3-13%; and following ultrasonic scaling it was 13-23%.

Clinical Implications: Bacteremia occurs with and without treatment and not as often as you might expect. Perhaps people with periodontal disease develop defense tactics to protect themselves against live bacteria entering the blood stream. What still needs to be determined is where the bacteria lodge, and what impact they have on various body organs, such as the liver and heart.

Kinane, D., Riggio, M., Walker, K., MacKenzie, D., Shearer, B.: Bacteraemia Following Periodontal Procedures. J Clin Perio 32: 708-713, 2005.

Visible plaque more predictive of treatment outcome than microbial testing

We all know that measuring treatment outcomes on the day of therapy cannot be done because probing depths and attachment levels improve over time, plus healing may continue over several months after treatment. Periodontal risk factors have been identified, yet parameters predicting early treatment outcomes have not. With such parameters, clinicians could determine, after the first stage of treatment, the potential need for additional, alternative, or aggressive therapy.

Are clinical signs more predictive of treatment success than microbiological testing? Researchers at the University of Geneva in Switzerland carefully monitored 10 patients for six months to determine the answer to this question. Study participants all had at least four teeth with probing depths of 6 mm or more. The tooth surface with the deepest pocket was designated as the site for subgingival bacterial sampling for microbial testing. Specific bacterial species were identified in each sample. Plaque, bleeding on probing, probing depths and attachment levels were also measured at baseline, three months, and six months.

Two to three weeks prior to baseline measurements, patients all received supragingival deposit removal and oral hygiene instructions––the hygienic phase. Following baseline data collection, scaling and root planing were done by a periodontal graduate student with a sonic scaler and hand instruments over a series of four visits for each patient. Following instrumentation, pockets were irrigated with 0.1% chlorhexidine (CHX) and patients rinsed at home with CHX for one week after treatment.

The microbial testing was anticipated to be very predictive of treatment outcome, but that wasn’t the case. Age was related to the persistence of subgingival bacteria after treatment. Older patients were more likely to still have specific species in the pockets at six months than were younger patients.

Visible plaque after the hygienic phases of treatment was the most predictive of treatment outcome six months later. Total bacterial counts also correlated to bleeding at six months.

Clinical Implications: Focus on plaque levels from the start and bleeding scores during maintenance. Time and attention is well spent reinforcing oral hygiene instructions. Use your knowledge, skills, and creativity to find the best ways for patients to remove as much plaque as possible. The goal of therapy is still the elimination of pockets and bleeding.

Brochut, P., Marin, I., Baehni, P., Mombelli, A.: Predictive value of Clinical and Microbiological Parameters for the Treatment Outcome of Scaling and Root Planing. J Clin Perio 32: 695-701, 2005.

Half of surgical patients will be re-treated during maintenance

According to the research, patients who comply with recommended maintenance and oral hygiene suggestions are less likely to lose teeth over time. Compliance findings vary between 16% and 87%, with most researchers agreeing on a rough estimate of 33% of surgical patients complying with recommended maintenance. To date, no studies have evaluated the need for re-treatment during maintenance, for those completing periodontal surgery.

Researchers in Norway evaluated the records of a private periodontal practice, focusing on patients visiting the practice between January and April 2003. One hundred patients were selected who had undergone periodontal surgery at least 10 years prior and had continued in maintenance. Patients who had undergone surgery, failed to comply with oral hygiene and the recommended maintenance, and also refused suggested re-treatment were not included in the study. This indicates that the findings from this investigation will report less need for re-treatment than there actually was.

Patients alternated between the periodontist’s office and their general dentist for maintenance therapy. Patients in the periodontal office received oral hygiene review, scaling and root planing, polishing, and occlusal adjustments, if necessary. Re-treatment indicators were pockets of 7 mm or more with bleeding or sites showing a change of 3 mm or more, with bleeding.

Half the patients required re-treatment over the maintenance period. Six were treated with systemic antibiotics, four received non-surgical therapy, and 40 required additional surgery. Those with a poor prognosis at the beginning of treatment, poor compliance with both maintenance and oral hygiene, and those with a family history of periodontal disease were more likely to need re-treatment. Family history of periodontal disease was the least predictive of these three risk factors, but does support the fact that genetics do play a part in dental disease. This is the first study to evaluate the need for re-treatment following periodontal surgery.

Clinical Implications: Following periodontal surgery, maintenance compliance and good oral hygiene are essential for those wanting to avoid re-treatment.

Fardal, O., Linden, G.: Re-Treatment Profiles During Long-Term Maintenance Therapy in a Periodontal Practice in Norway. J Clin Perio 32: 744-749, 2005.