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Perio Reports Trisha E. O'Hehir, RDH, BS Editorial Director, Hygienetown Magazine

More by this author (282)
Perio Reports  Vol. 21 No. 2
Perio Reports provides easy-to-read research summaries on topics of specific interest to clinicians.
Perio Reports research summaries will be included in each issue to keep you on the cutting edge
of dental hygiene science.
Bacteria hide in epithelial cells

Mechanical debridement of subgingival areas can successfully treat most cases of periodontitis. However, there are cases of aggressive periodontitis that might respond to treatment initially, but then relapse due to reinfection. In addition to mechanical debridement, attempts have been made to control oral bacteria through the use of systemic antibiotics and antimicrobial rinses.

Several researchers have reported that periodontal pathogens are capable of invading oral epithelial cells. Laboratory studies have confirmed that A actinomycetemcomitans and T forsythia can invade epithelial cells and that P gingivalis can invade fibroblast cells. This suggests that bacteria can evade treatment by penetrating tissue cells.

Periodontal researchers at the University of Minnesota’s School of Dentistry evaluated tissue cells following comprehensive periodontal treatment to determine if these cells provided a safe hiding place for bacteria. Eighteen patients with aggressive periodontitis received oral hygiene instructions, mechanical debridement of supra and subgingival surfaces under anesthesia in two visits scheduled within three days. On the last day of treatment patients were given a prescription for 500mg amoxicilliin and 250mg metronidazole to be taken three times daily for seven days. They were also instructed to rinse twice daily with 0.12 percent chlorhexidine for 30 days.

Clinical, microbiological and cell samples were taken at baseline three months and six months. Clinical healing was evident from probing depths and bleeding scores. Microbial analysis showed reductions in certain bacterial species in the subgingival plaque, but cell cultures showed an increase rather than a decrease in bacteria invading tissue cells. More research is needed to see which, if any, antibiotics are capable of penetrating tissue cells.

Clinical Implications: In cases of aggressive periodontitis, reinfection might be caused by bacteria that evade mechanical, antibiotic and antimicrobial treatment by invading human epithelial cells.

Johnson, J., Chen, R., Lenton, P., Zhang, G., Hinrichs, J., Rudney, J.: Persistence of Extracrevicular Bacterial Reservoirs After Treatment of Aggressive Periodontitis. J Perio 79: 2305-2312, 2008.
Reasons for maxillary implant failures

Bone quantity and bone quality provide challenges for clinicians placing maxillary posterior implants. Sinus elevation and augmentation procedures are often done to increase the dimension of the posterior maxilla prior to implant placement. Previously published research reports the success rate for implants placed following sinus procedures to be 36 percent to 100 percent, depending on the study.

Researchers at the University of Connecticut Health Center looked back over charts of 136 consecutive patients receiving maxillary posterior implants. These patients ranged in age from 16 years to 80 years. Women comprised 43 percent of the group, men 57 percent. The group included both smokers and non-smokers and five percent of subjects had well-controlled diabetes. Followup data were available for an average of three years, and a range of six months to seven years. A total of 273, rough surface implants were placed for these patients.

Sinus elevations and augmentations of various kinds were done for 57 patients who received a total of 116 implants. The other 79 patients had a total of 157 implants placed in native bone.

The overall survival rate for these implants was 95 percent with 14 implant failures in 13 people. There were eight early failures and six failures after loading. Nine implants failed in the sinus lift group compared to five failures in the native bone group. Statistical analysis including multivariate analysis of various risk factors determined that smoking and postoperative infections were the greatest risk factors for these maxillary posterior implants. Higher implant failure was not associated with the sinus lift procedures.

Clinical Implications: Smoking cessation should be an integral part of the treatment plan when placing implants for those who smoke.

Huynh-Ba, G., Friedberg, J., Vogiatzi, D., Ioannidou, E.: Implant Failure Predictors in the Posterior Maxilla: A Retrospective Study of 273 Consecutive Implants. J Perio 79: 2256-2261, 2008.
A magnified look inside the periodontal pocket

Until now, information about subgingival tissues and deposits was dependent upon open flap surgery for direct visual inspection. Today, the periodontal endoscope provides a magnified (48X) view of the subgingival area, rendering valuable information without the need for surgery.

Researchers compared traditional clinical examination findings with endoscopic findings in a group of 26 patients with moderate to severe periodontitis. More than 60 percent of inflamed pocket wall sites were seen opposite calculus covered with plaque biofilm as detected with the endoscope. Less than 30 percent of inflamed sites were associated with biofilm alone. Only five percent of inflamed sites were not associated with either biofilm or calculus covered with biofilm.

In a companion study involving six patients and 12 teeth scheduled for extraction, subgingival instrumentation was completed using the periodontal endoscope. Teeth and surrounding bone were removed six months later, providing three sections per tooth or a total of 36 sections for evaluation. No calculus or tissue inflammation was found on 35 of the 36 block sections. One section showed new calculus in the notch make with a bur to identify the edge of the calculus deposit removed. This patient continued to smoke and chose not to follow completely the oral hygiene regimen requested (weekly visits to reinforce oral hygiene for one month, monthly visits thereafter, and daily chlorhexidine rinses for six weeks).

Clinical Implications: To effectively eliminate tissue inflammation, complete removal of subgingival calculus needs to be the goal of instrumentation. Endoscopy provides new information about subgingival conditions.

Wilson, T., Harrel, S., Nunn, M., Francis, B., Webb, K.: The Relationship Between the Presence of Tooth-Borne Subgingival Deposits and Inflammation Found with a Dental Endoscope. J Perio 79: 2029-2035, 2008.

Wilson, T., Carnio, J., Schenk, R., Myers, G.: Absence of Histologic Signs of Chronic Inflammation Following Closed Subgingival Scaling and Root Planing Using the Dental Endoscope: Human Biopsies – A Pilot Study. J Perio 79: 2036-2041, 2008.
Treat during first trimester of pregnancy

Pregnancy gingivitis is reported to be between 35 to 100 percent during the second trimester, despite unchanged plaque levels. During pregnancy, estrogen and progesterone increase and might be responsible for gingivitis. Periodontitis is seen with advancing age, so more periodontitis might be seen in older pregnant women. Periodontal disease has been suggested as a risk factor for preterm and low birthweight, however, no studies have tracked subgingival bacteria at different times during normal pregnancy.

Researchers at the University of Bern in Switzerland monitored the natural change in 37 species of subgingival bacteria during normal pregnancy in a group of 20 women. None of the women received dental treatment during their pregnancies. Bacterial samples were collected from mesial surfaces all first molars at 12, 28 and 36 weeks of pregnancy and four-to-six weeks post partum. Full-mouth probing and bleeding scores were also recorded at these visits.

At both 12 weeks and postpartum, 2.5 percent of sites measured more than 4mm. Probing depths remained unchanged during pregnancy for these healthy women with normal pregnancies. Bacteria associated with periodontitis did not change during the study, however the colonization patterns suggest that between 12 and 28 weeks of pregnancy the tissues may be more susceptible to infection. Bacteria associated with early colonization of biofilm were found in areas of bleeding upon probing. These findings suggest periodontal treatment should be done as soon as the woman knows she is pregnant.

Clinical Implications: Periodontal treatment should be scheduled within the first three months of pregnancy, to establish periodontal health and reduce the risk of any potential pregnancy complication that may be linked to periodontal conditions.

Adriaens, L., Alessandri, R., Spörri, S., Lang, N., Persson, G.: Does Pregnancy Have an Impact on the Subgingival Microbiota? J Perio 80: 72-81, 2009.
Fluoridated salt reduces caries prevalence

Fluoridated salt has been tested in both Switzerland and Hungary as an alternative to water fluoridation. In Hungary, villages were compared for caries incidence while receiving either fluoridated salt or fluoridated water. Fluoridated salt was used from 1966 to 1985 with cariostatic effects similar to fluoridated water, 50-60 percent reduction in DMFT rates for children five-to-14 years of age.

Researchers returned to the villages in 1991 to reevaluate caries prevalence. Residents currently between the ages of 18 and 47 were evaluated. A control group was also included that had no access to fluoride.

Those in the water-fluoridated areas demonstrated less caries than the fluoridated salt subjects. Those 18-27 years old, receiving fluoridated water had DMFT scores of 6 compared to 8 for those receiving fluoridated salt.

Scores for those of the same age not receiving any fluoride were 14. Scores for 28-37-year-olds were 10, 13 and 17 respectively. For those 38-47 years old, scores were 13, 15, and 19. Those who began using fluoridated salt at an early age, benefited most. Those who were adults when the study began received some benefit, but not as great as the younger residents. No fluorosis was reported for those receiving fluoridated salt.

At the time of the fluoridated salt study, prepackaged foods were not used by families in the village. Families used salt for curing meats, making preserves and pickles, etc. Each person consumed approximately 3.3 grams of salt per day compared to others in Western Europe who reportedly consumed 1.5 to 2 grams of salt/day.

Clinical Implications: Viruses are associated with periodontitis, but their exact mechanism of action in periodontal pockets is not yet known.

Imbronito, A., Okuda, O., de Freitas, N., Lotufo, R., Nunes, F.: Detection of Herpes Viruses and Periodontal Pathogens in Subgingival Plaque of Patients with Chronic Periodontitis, Generalized Aggressive Periodontitis, or Gingivitis. J Perio 79: 2313-2321, 2008.




Top: Active Herpes simplex virus infection in esophagus ulcer. Photo courtesy of CDC/Dr. Edwin P. Ewing, Jr.

Middle: This electron microscopic image shows two Epstein Barr Virus
viral particles. Photo courtesy of
PLS/Liza Gross

Bottom: Cytomegalovirus infection of a lung pneumocyte. Photo courtesy of CDC/Dr. Edwin P. Ewing, Jr.
Effects of weekly plaque control instructions

Supragingival plaque biofilm and tissue inflammation contribute to subgingival bacterial growth. Controlling supragingival biofilm should reduce subgingival bacterial counts, but the research is divided on this issue. These differences may be due to variations between studies in the quality of supragingival biofilm control or variations in microbial testing. Currently, researchers agree that real-time polymerase chain reaction (PCR) is the test of choice.

Researchers in Brazil evaluated the effects of weekly oral hygiene instructions on clinical indices and subgingival microbiological levels. Achieving optimal daily supragingival biofilm removal was the goal of 24 never-smokers and 21 smokers with moderate to severe periodontitis.

At baseline, supragingival deposits were removed with hand instruments and subjects were instructed in the Bass technique of toothbrushing and interdental cleaning. They returned for weekly instruction in oral hygiene for the six-month study. Patients were examined at one, three and six months. Subgingival bacterial samples were taken from four sites on each patient, two from pockets 3-5mm and two from pockets 6mm or deeper.

No significant differences were observed between smokers and people who never smoked. There were dramatic reductions in subgingival bacterial counts for both groups. Deeper pockets harbored higher counts than shallower pockets and higher counts were associated with pocket that showed bleeding upon probing. Pocket depths reduced slightly more than 1mm in 3-5mm pockets and 2mm in deeper pockets.

Clinical Implications: These findings reaffirm the value of effective daily supragingival plaque control on subgingival bacterial counts and tissue healing. Daily plaque control is pivotal to achieving and maintaining periodontal health.

Gomes, S., Nonnenmacher, C., Susin, C., Oppermann, R., Mutters, R., Marcantonio, R.: The Effect of a Supragingival Plaque-Control Regimen on the Subgingival Microbiota in Smokers and Never-Smokers: Evaluation by Real-Time Polymerase Chain Reaction. J Perio 79: 2297-2304, 2008.
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