Perio Reports

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.

Experimental Antibacterial Adhesive May Inhibit Root Caries

Root surface caries present a challenge to the treating clinician as no simple option is available for halting the progression of these lesions. Fluoride in its many forms provides our primary defense. Products include professional fluoride treatments, fluoride rinses, gels, pastes and varnishes. Adhesive agents are also being considered.

Researchers at Osaka University in Japan tested an experimental adhesive agent and compared it to three bonding agents in laboratory tests on teeth with artificially induced caries demineralization. The experimental bonding agent, MDPB*, has antibacterial properties and has been shown to penetrate artificially demineralized lesions and kill bacteria in dentin. It was compared in this study to Prime & Bond from Dentsply, Single Bond from 3M ESPE and Liner Bond 2 from Kuraray.

Human bicuspids were used for testing. The crowns and root tips were removed from these teeth, and the root surfaces were coated with clear nail polish except for a 4 mm window on facial and lingual surfaces. The teeth were then soaked in acid for two weeks to produce demineralized lesions. After that, they were rinsed, dried, and the assigned products were applied. (No acid etch was used for any of the products tested as all surfaces had been etched in the two-week acid bath.) Five specimens were treated with each product before placement in an acid-gel bath for two weeks. Control specimens, which received no adhesive bonding agent, were also included.

Microscopic evaluations of the control teeth revealed a shallow lesion at two weeks and a much deeper lesion at four weeks. The experiment adhesive successfully maintained the two-week level of demineralization, while the other products were washed away and further demineralization occurred. Bear in mind that this is a laboratory test and results need to be tested on humans now, but it is encouraging to see that progress is being made in the development of treatment options for root surface decay.

Clinical Implications: This experimental adhesive tested in this research is not yet available, but the need for a product to stop demineralization and potentially remineralize areas of root surface decay is needed. Keep an eye on the market for new products directed at the treatment and prevention of root caries.

*MDPB: 12-methacryloyloxydodecylpyridinium bromide

Kuramoto, A., Imazato, S., Walls, A., Ebisu, S.: Inhibition of Root Caries Progression by an Antibacterial Adhesive. J Dent Research 84: 89-93, 2005.

Zinc Supplements Improve Taste Disorder

Dysgeusia, defined primarily as a distorted taste perception, can also include a persistent sense of taste even in the absence of a taste stimulus. Reported changes in taste are usually related to those that are bitter, sour or metallic. An altered sense of taste can be caused by systemic, neurologic, psychiatric, or metabolic disease. Drugs are also known to interfere with taste.

Zinc has been used to treat taste problems, but results are mixed. Zinc is a trace element that is rapidly transferred into individual cells, especially cells with a high turnover rate, such as taste bud cells. Zinc is very important in the regeneration of taste bud cells as well as the synthesis of growth hormones and the regulation of metalloprotein expression.

Researchers at the University of Erlangen-Nuremberg in Germany compared zinc supplementation to a placebo to determine the effect on taste perception in subjects with dysgeusia. Fifty subjects with idiopathic dysgeusia were randomly assigned to either the test or control group and instructed to take one pill daily on an empty stomach with a full glass of water. The study lasted three months.

Baseline data included blood tests, depression and mood testing, self-rated taste disorder, and an extensive taste test using a total of 32 filter paper strips impregnated with four different concentrations of four tastes. The strips were placed on the right and left sides of the front of the tongue and the patient asked to identify the taste as sweet, sour, salty or bitter. The self-test was a visual analog scale in which subjects ranked their perception of their taste disorder. The line had 10 units with one end representing “no impairment” and the other representing “extreme impairment.” Depression and mood were evaluated with psychological tests.

Subjects taking supplemental zinc demonstrated improved taste both on the paper strip test and the self-rated test. Signs of depression or lowered mood were improved in the zinc group. No side effects were reported. Scores remained the same for the control group.

Clinical Implications: Treatment with a dietary zinc supplement is helpful for people suffering from idiopathic dysgeusia or a taste disorder of unknown cause.

Heckmann, S., Hujoel, P., Habiger, S., Friess, W., Wichmann, M., Heckmann, J., Hummel, T.: Zinc Gluconate in the Treatment of Dysgeusia-A Randomized Clinical Trial. J Dent Research 84: 35-38, 2005.

15-Second Rinse With Chlorhexidine Controls Plaque Accumulation

Chlorhexidine (CHX) is the “gold standard” for chemical plaque control, specifically when mechanical cleaning is suspended, difficult or inadequate. The effectiveness of CHX is attributed to its substantivity or ability to adhere to surfaces, resulting in antimicrobial activity for seven to 12 hours.

The exact mechanism of action is still debated. Some focus on the ability of CHX to adhere to mucosal tissue and thus provide antibacterial activity; others have determined that CHX adsorbs to the tooth surface within 15 seconds. It is possible that the CHX molecule attaches to the pellicle layer on the tooth with one end and with the other end competes with bacteria attempting to colonize the surface. Based on this theory, plaque inhibition occurs solely on the tooth surface, not in other areas of the mouth.

Researchers in the Netherlands compared three rinsing times to determine if plaque accumulation would be affected. A total of 90 dental students participated in this 72-hour study. At baseline they all received dental hygiene care to bring their mouths to a plaque-free state. Subjects were all given oral and written instructions to rinse twice daily, morning and evening, and to refrain from all mechanical oral hygiene. They were randomly assigned to rinse for 15 seconds, 30 seconds, or 60 seconds. At the end of 72 hours, plaque scores were taken. No differences were observed between the different rinsing times and plaque accumulation.

Clinical Implications: Shorter rinsing times may be helpful for compliance with CHX rinsing. These findings confirm that plaque inhibition is achieved with a 15-second rinse. Further studies are needed to confirm the effectiveness of a 15-second rinse to control gingivitis.

Van der Weijden, G., Timmerman, M., Novotny, A., Rosema, N., Verkerk, A.: Three Different Rinsing Times and Inhibition of Plaque Accumulation with Chlorhexidine. J Clin Perio 32: 89-92, 2005.

Caries Prevention Needed After Periodontal Therapy

It makes sense that a shift in bacteria will occur following non-surgical-therapy from a predominantly periodontopathic flora to one that is cariogenic. Several studies have documented an increase in the incidence of root caries following both surgical and non-surgical periodontal therapy.

To determine if indeed a shift in bacterial counts does occur, the Belgian research team that has published several studies on full-mouth disinfection monitored bacterial counts for eight months following treatment. A total of 71 patients with advanced periodontal disease participated. They were randomly assigned to one of five groups–two for control (one positive and one negative), and three for testing.

The negative control group received quadrant scaling and root planing at two-week intervals. The positive control group received full-mouth disinfection (FMD), with all instrumentation completed within 24 hours. The three test groups all received FMD followed by different antiseptic mouthrinses: 1) chlorhexidine (CHX) for two months; 2) fluoride (amine/stannous) for two months; or 3) CHX for two months and then fluoride for the remaining six months.

Before and after bacterial counts showed an increase in the number of strep mutans for both control groups. For the CHX group, strep mutans were not detected at two months but rebounded thereafter. The fluoride group showed a slight reduction at two months and a recurrence after that. The only group to show no detectable strep mutans was the CHX plus fluoride group.

No significant changes were evident for lactobacillus counts in any of the groups. Tongue bacterial counts remained unchanged in the fluoride group despite tongue brushing. Reductions in tongue bacterial counts were evident in the CHX group.

Clinical Implications: Since there is a shift from periodontal pathogens to cariogenic pathogens following non-surgical therapy, be sure to incorporate a root caries prevention protocol with your periodontal therapy.De Soete, M., Dekeyser, C., Pauwels, M., Teughels, W., van Steenberghe, D., Quirynen, M.: Increase in Cariogenic Bacteria After Initial Periodontal Therapy. J Dent Research 84: 48-53, 2005.

Not All End-Rounded Bristles Are The Same

End-rounded toothbrush bristles have been recommended since at least 1948 when a study reported gingival trauma due to sharp filament tips. Around that same time, Dr. Charles C. Bass, the inventor of the Bass Technique, espoused the need for rounded filaments with no sharp points. Several studies have reported on the varying degrees of end-rounding, based on microscopic evaluations of the bristles. Until now, studies have been limited to manual brushes.

The first study evaluating power toothbrush bristles was recently conducted in Berlin, Germany. Visiting various drug stores in Berlin, researchers purchased five brushes for each of the 15 European power toothbrushes now available. Bristle tufts as well as individual bristles were evaluated microscopically to determine acceptability of the bristle end-rounding.

The degree of end-rounding varied between brushes and in some cases between bristles within a single tuft.

Meyer-Lueckel, H., Rieben, A., Kielbassa, A.: Filament End-Rounding Quality in Electric Toothbrushes. J of Clin Perio 32: 29-32, 2005.

Treating Part Of The Mouth Heals Untreated Sites

Traditionally clinical healing following instrumentation has been attributed to the removal of bacterial deposits. An alternative hypothesis suggests that the bacteremia caused by instrumentation activates the immune response, resulting in clinical healing. Clinicians report seeing healing in untreated quadrants as they progress through quadrant scaling and root planing visits over several weeks or months.

Researchers at the University of Washington in Seattle designed a study to measure the effects of scaling and root planing on a single untreated quadrant when the other three quadrants were treated. In order to measure clinical changes over a short period of time, patients recruited for this study all had generalized aggressive periodontitis. Twenty patients participated in the six-month study with 11 receiving treatment and nine assigned to the control group and receiving no treatment.

Treatment consisted of scaling and root planing in three quadrants at baseline and again at three months. No oral hygiene instructions were provided to any of the subjects during this study. Extensive examination and testing were done on all subjects at three-week intervals for the first three months, then again at months four and six. Visits included blood tests, gingival crevicular fluid sampling, plaque sampling, clinical data and radiographs. The exhaustive appointment schedule was difficult for many patients.

At the end of the study, all groups had similar plaque scores. Probing depths declined for all groups, but only slightly for those who didn’t receive treatment. Perhaps the frequent probing and plaque sampling was a form of therapy! Alveolar bone height increased for the treated sites and the untreated sites in the treated mouths, and decreased in the untreated group. As expected, subgingival bacterial levels remained unchanged for the untreated group. Bacterial reductions were observed in the treated group and for some–but not all–bacterial species tested in the untreated sites in the treated mouths. The pocket depth and bone improvement in the untreated sites in the treated mouths were approximately 30% of the healing observed in the treated sites.

Clinical implications: It may be that when part of the mouth is treated, the immune system is triggered and that leads to healing around untreated teeth. These finding confirm what clinicians have observed over the years, i.e., as quadrants are treated, the remaining quadrants show signs of healing.

Pawlowski, A., Chen, A., Hacker, B., Manci, L., Page, R., Roberts, F.: Clinical Effects of Scaling and Root Planing on Untreated Teeth. J Clin Perio 32: 21-28, 2005.