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.

Systemic antibiotics enhance healing for aggressive periodontitis

Aggressive periodontitis is a rare form of gum disease characterized by early onset and severe bone loss that can lead to edentulism at an early age. Researchers at the Eastman Dental Institute in London compared full-mouth instrumentation within 24 hours with and without systemic antibiotics to determine differences in healing.

All subjects received oral hygiene instructions and supragingival instrumentation prior to the start of the study in an attempt to bring each individual’s plaque level to 20% or less. The placebo or control group began the study with an average plaque score of 20%, and the test group’s average plaque score was higher, at 25.5%. The test group also started out with higher full-mouth bleeding scores: 61.5% compared to 55% for the control group.

One experienced clinician provided full-mouth instrumentation using local anesthesia, an EMS Piezon® scaler and hand instruments. Instrumentation was completed with a long visit before lunch for two quadrants, and a long visit after lunch to complete the remaining quadrants. Patients were instructed to rinse twice daily with 0.2% chlorhexidine for two weeks. No subgingival instrumentation was provided during the six-month test period.

All patients were given two bottles of pills and instructed to take one of each, three times daily for seven days. Only the research coordinator knew who received the antibiotics (500 mg of amoxicillin and 500 mg of metronidazole), and who received placebo pills. The code was broken after the study was completed.

Both groups demonstrated good healing at two and six months, with the test group showing a greater average pocket depth reduction, 3 mm in the test group compared to 2 mm in the control group and more deep pockets being resolved. At two months, 49% of pockets in the test group and 42% of pockets in the placebo group converted from 4 mm or deeper to 3 mm or less. At six months, the figures were 55% for the test group and 37% for the placebo group.

Clinical Implications: Systemic antibiotics may enhance healing for those with aggressive periodontitis when combined with full-mouth instrumentation. Do remember that the control group also had subjects with outcomes comparable to the test group, but that more patients and more pockets experienced greater healing with the added antibiotic. The research challenge now is to determine which patients and which clinical characteristics or risk factors benefit from the systemic antibiotics.

Guerrero, A., Griffiths, G., Nibali, L., Suvan, J., Moles, D., Laurell, L., Tonetti, M.: Adjunctive Benefits of Systemic Amoxicillin and Metro-nidazole in Non-Surgical Treatment of Gener-alized Aggressive Perio-dontitis: A Randomized Placebo-Controlled Clinical Trial. J Clin Perio 32: 1096-1107, 2005.

Higher antibiotic concentrations needed to impact biofilms

Antibiotic effectiveness is usually tested in the laboratory against planktonic or individual, floating bacteria. The minimal inhibitory concentration (MIC) of an antibiotic needed to kill individual bacteria grown in a laboratory is the basis of dosage recommendations today. Emerging information about the complexity of bacterial plaque biofilms suggest that higher concentrations of antibiotics are needed to control bacterial growth within the protective slime of a biofilm.

Researchers in Germany tested four antibiotics against three strains of bacteria allowed to grow in single species biofilms. The antibiotics included: clindamycin, doxycycline, metronidazole, and moxifloxacin. Besides a control with no antibiotic, the test concentrations included: one-fold MIC, five-fold MIC, 10-fold MIC, 50-fold MIC, and 100-fold MIC.

The bacteria selected for biofilm growth included Streptococcus constellatus (Sc), which is usually found in severe recurrent forms of periodontitis, Porphyromonas gingivalis (Pg), and Actinobacillus actinomycetemcomitans (Aa).

Since the preliminary findings revealed the ineffectiveness of metronidazole against even single bacteria in a planktonic form, metronidazole was only tested against Pg in a biofilm. It took a 100-fold concentration of metronidazole to effectively kill Pg in a biofilm. Clindamycin concentrations up to 100-fold had no effect on Sc or Aa. It took a 50-fold concentration to kill the bacteria in a Pg biofilm.

Doxyclycline wasn’t effective against Sc at any concentration. It took a 10-fold concentration to kill Aa and a 50-fold concentration to kill Pg. Moxifloxacin was the most effective antibiotic tested against all three bacterial biofilms. Moxifloxacin concentrations of 50-fold killed Sc, and one-fold killed both Aa and Pg. These findings are all for 48-hour exposures. Shorter exposures required higher drug concentrations.

Clinical Implications: These findings are the beginning of research needed to determine the most appropriate antibiotics and accurate dosages of these systemic drugs to be used in the treatment of aggressive periodontal disease.

Eick, S., Seltmann, T., Pfister, W.: Efficacy of Antibiotics to Stains of Periodontopathogenic Bacteria Within a Single Species Biofilm – An In Vitro Study. J Clin Perio 31: 376-383, 2004.

Classic Study
No evidence to support theory that nicotine causes vasoconstriction

In 1947, an eminent Danish scientist, Dr. J. J. Pindborg, published his hypothesis explaining why smokers exhibited less bleeding with periodontal disease than non-smokers. He suggested that the nicotine in cigarettes could act directly on the blood vessels of the gingivae, causing vasoconstriction. This action would reduce blood flow and possibly decrease the number of blood cells and the amount of oxygen at the same time. Vasoconstriction would also reduce the ability to remove toxins and waste products from the area. It seemed to make sense, but it was never proven scientifically until the use of heat diffusion transducers.

Heat diffusion transducers were used to monitor gingival blood flow in a rabbit. Nicotine caused an initial decrease in blood pressure and a significant increase in blood flow, assumed to be an increase in blood vessel diameter. Within 10 minutes, these effects were reversed and the results were assumed to be vasoconstriction. These findings supported Dr. Pingbord’s vasoconstriction theory.

Gingival blood flow has been studied since the 1950s using vital microscopy, plastic microspheres implanted systemically into the internal carotid arteries, infused radioisotopes, radiolabelled microspheres, and high speed cinematography in animal models. These studies looked at blood flow in general, not how it was affected by smoking. Today, laser Doppler technology is being used to monitor blood flow. Readings are based on shifts in back-scattered laser light measured through skin and gingivae.

Researchers at Guy’s Hospital in London used the laser Doppler to measure blood flow in maxillary interdental papillae and on the forehead during and after smoking. Study subjects were connected to the laser Doppler for a total of 70 minutes. Twenty-one heavy, light, and non-smokers participated in the trial. Blood cotinine levels (the major metabolite of nicotine that indicates levels of nicotine intake) were measured both at baseline to confirm smoking status and during the trial to monitor changes.

The first 10 minutes were used to adjust the machine and start the continuous readings. The next 10 minutes were considered a rest period. For five minutes, all subjects participated in “sham smoking” using a straw. After this, light and heavy smokers were given a cigarette to smoke over the next five minutes. Non-smokers continued to “sham smoke.” After smoking, subjects were monitored for an additional 40 minutes.

The light smokers were the only ones to show an increase in blood flow during smoking. Non-smokers and heavy smokers didn’t demonstrate a significant change in either gingival or forehead blood flow. It may be that heavy smokers develop a tolerance to the effects of nicotine over time. Other researchers have shown an increase in blood flow during smoking, which they related to an increase in blood pressure and heart rate. Yet researchers looking at blood flow have not been able to show any vasoconstriction caused by smoking.

Clinical Implications: We know that smokers with periodontal disease exhibit less bleeding than non-smokers with periodontal disease. We just don’t know what causes it. Based on several studies, nicotine does not cause vasoconstriction; therefore, it must be something else related to the nicotine or the thousands of other chemicals in cigarettes that reduce bleeding.

Meekin, T., Wilson, R., Scott, D., Ide, M., Palmer, R.: Laser Doppler Flowmeter Measurements of Relative Gingival and Forehead Skin Blood Flow in Light and Heavy Smokers During and After Smoking. J Clin Perio 27: 236-242, 2000.

Passive smoke may also be a risk factor for periodontal disease

Smoking is the greatest environmental risk factor for periodontal disease. According to the research, active smokers are three times more likely to experience severe periodontitis than non-smokers. Nearly 40% of periodontitis cases are thought to be attributed to smoking. Studies are now being done to measure the influence of passive smoke on periodontitis. A study published in 2001 found passive smokers to be 1.6 times more likely to have periodontal disease than non-smokers.

Researchers at Osaka University in Japan evaluated 273 Japanese factory workers to determine the influence of active and passive smoking on periodontal disease. Data were collected from clinical examinations, written questionnaires and salivary samples used to detect the nicotine breakdown product, cotinine. Nicotine has a very short half-life of two hours in the blood stream; cotinine has a much longer half-life of 19 hours.

Active smokers and non-smokers with high cotinine levels demonstrated greater probing depths and more attachment loss than non-smokers. The self-reported exposure to passive smoke did not correlate with cotinine levels. The authors suggested that people exposed to passive smoke may not be aware of the extent or the many places they are exposed, thus leading to low levels of reported exposure despite elevated salivary cotinine levels.

Clinical Implications: Ask non-smoking patients specific questions about their exposure to environmental smoke. When compared to non-smokers, those exposed to passive smoke may be nearly three times more likely to experience periodontal disease.

Yamamoto, Y., Nishida, N., Tanaka, M., Hayashi, N., Matsuse, R., Nakayama, K., Morimoto, K., Shizukuishi, S.: Association Between Passive and Active Smoking Evaluated by Salivary Cotinine and Periodontitis. J Clin Perio 32: 1041-1046, 2005.

Repeated polishing does not remove significant dentin

Removing tooth structure with polishing has always been a concern when dentin is exposed. Researchers have estimated that during a rubber cup polishing, 4.5 seconds are spent to clean a single surface (6 minutes per full mouth). To determine the effects of polishing with either a prophy brush or rubber cup, researchers measured dentin removal on extracted teeth. Seventy-two extracted teeth were imbedded in acrylic and all enamel removed to expose dentin. A laboratory toothbrushing machine was configured to hold a prophy angle with either a rubber cup or brush on the flattened surface of each tooth for 80 seconds moving over a 13 mm area of the dentin. The 3 mm target test area was actually polished for 37 seconds, a figure that equates to eight professional polishings. Both standard prophy brushes and cups from the KerrHawe Company in Switzerland were used with four prophy pastes each. In addition, a fluoride releasing rubber cup with imbedded abrasives was used to create a ninth test group. The prophy pastes included: Nupro® Coarse, Hawe Cleanic®, pumice plus glycerine, and calcium pyrophosphate plus glycerine.

The differences were minimal between products used with the rubber cup. Greater surface loss was measured when Nupro Coarse was used with the nylon brush compared to the other prophy pastes used with a brush. The pasteless prophy cup also demonstrated more surface loss than the other combinations. The measurements were in micro millimeters. In a worst case scenario, 0.1 mm of dentin would be lost after 11 to 69 years – depending on how many professional polishings were performed each year.

Clinical Implications: There is no need to worry about removing dentin when polishing with either brushes or rubber cups as minimal dentin is removed.

Zimmer, S., Barthel, C., Coffman, L., Raab, W., Hefferren, J.: Evaluation of Dentin Abrasion During Professional Tooth Cleaning in an In Vitro Model. J Clin Perio 32: 947-950, 2005.

Snuff (spit tobacco) use leads to mucosal changes

In Sweden, a person must be 18 years of age to purchase tobacco, although underage young men can more easily purchase tobacco than can underage young women. Snuff is easier to buy than cigarettes for those under 18. Ice hockey playing is highly associated with snuff use in Sweden. Most young men place the snuff in the mucosal fold above the maxillary anterior teeth, on either the right or left side or in the middle.

Swedish researchers at Karlstad University evaluated the oral health of 16 to 25-year-old hockey players. Two experienced hygienists performed examinations and took photographs of mucosal lesions on 80 young men. Half were snuff users; the other half weren’t. Mucosal lesions were classified from one to four, with one being an early lesion not yet changing the tissue color and with no thickening of tissue. Four was classified as a heavily wrinkled, colored and thickened lesion. None of the study participants presented with a Class 4 lesion.

Oral lesions were found in 35 of the 40 snuff users. Those who used more snuff and used it for longer periods each day were more likely to have a lesion. For each hour of daily snuff use, the odds of having an oral lesion increased by four. More recession was also found among snuff users when compared to non-users.

No differences were demonstrated for gingivitis, plaque or pocket depth between those using snuff and those not using snuff.

Clinical Implications: New approaches need to be developed that effectively convince young people of the dangers of snuff (spit tobacco) use. If Sweden is an indication, high numbers of young men involved in sports are using snuff.

Rolandsson, M., Hellqvist, L., Lindqvist, L., Hugoson, A.: Effects of Snuff on the Oral Health Status of Adolescent Males: A Comparative Study. Oral Health Prev Dent: 3: 77-85, 2005.