A paper by Brazilian researchers is one of the most cited in the field of odontology

A study published in one of the field’s most influential journals showed that periodontitis treatment can be improved when accompanied by antibiotics.

By Elton Alisson

Agência FAPESP – An article published in the Journal of Clinical Periodontology by researchers from the Universidade Guarulhos (UnG) Post-Graduate Odontology Program is among the most cited and accessed in odontology’s most scientifically influential periodical.

The article presents the results of a study carried out with FAPESP funding showing that conventional treatment of bacterial infections affecting the gum tissue and other tissues surrounding the teeth (periodontitis) can be significantly improved through the concomitant use of the antibiotics metronidazole and amoxicillin.

The researchers evaluated a group of 30 patients treated at the UnG Clinical Odontology Studies Center for aggressive periodontitis. Periodontitis is a rare type of bacterial infection that normally affects younger people and is characterized by the rapid loss of supporting bone tissue (alveolar bone), which can lead to the loss of teeth, especially molars and incisors.

Traditionally, this illness and other types of periodontal infections are treated by mechanical scraping and smoothing of the tooth roots to remove the bacteria that colonize the region between the teeth and gums and attack the alveolar bone. However, many young patients do not respond well to this treatment and undergo disease recurrence.

When combining conventional treatment with the use of metronidazole and amoxicillin in half of the patients participating in the study, the UnG researchers found that after three months, patients receiving the combined treatment showed a better clinical response than those that only received the conventional treatment. In addition, recolonization of the biofilm below the gum line was also improved.

“We observed that the oral microbiota in patients subjected to mechanical cleaning and antibiotic therapy contained a greater proportion of beneficial bacteria and a lower proportion of pathogens. These differences remained for a longer period when compared to the patients treated only in the conventional manner,” said Magda Feres, coordinator of the UnG post-graduate Odontology program and one of the researchers that participated in the project, to Agência FAPESP.

To evaluate the dental plaque of patients with aggressive periodontitis who participated in the study, the researchers used a molecular technique for microbiological analysis called checkerboard DNA-DNA hybridization, which identifies bacteria using DNA analysis.

The technique, developed by Sigmund Socransky of the Forsyth Institute, associated with Harvard University, is currently used in only six laboratories in the world and was installed at the UnG Microbiology Lab by Feres, who completed her doctorate at the North American institution as Socransky’s advisee.

“This method revolutionized the diagnosis of periodontitis and allowed for the results to be accompanied by an evaluation of the diverse bacteria associated with gum tissue infection, and many dental plaque samples can be obtained from each patient’s teeth to observe changes in the composition of the oral microbiota.” explained Feres.

Using this technique with a set of 40 oral microbiota bacteria, the researcher and her group were able to evaluate the changes to the patients’ oral bacteria brought about by the combination of the traditional treatment for aggressive periodontitis and medication containing metronidazole and amoxicillin. Only some of these oral bacteria are beneficial, while others are associated with periodontitis. 

The exams showed that the antibiotics helped promote improved patient biofilm recolonization, which showed a greater proportion of beneficial bacteria than pathogenic bacteria in comparison with the patients that only received conventional treatment.

“We found that the patients who did not take antibiotics had a greater and faster return of pathogens after treatment, while the microbiota of those who received medication remained more stable and improved, resulting in improved clinical parameters, such as reduced bleeding and disease regression,” said Feres.
The researchers have a new article in the final evaluation phases in the same periodical—the first was published in 2010—with the results of a study involving 120 adult patients in which they show that beneficial recolonization was maintained for one year in patients with chronic periodontitis, which is another type of periodontitis that is more common in adults.

Risk factors for systemic alterations

Periodontitis is caused by the colonization of the mouth by certain species of bacteria that can be transmitted from parents to children and that can reproduce along the edge of gum tissue when the host has low resistance.

When these bacteria settle at the edge of the gums, the host tries to free itself of them, setting off a rapidly evolving inflammatory process that produces metabolites that break down the tissue surrounding the teeth and the periodontal ligament (and alveolar bone).

As it is associated with a heavy load of bacteria that have negative health effects, some recent studies in an area of periodontics called periodontal medicine have suggested that a periodontal infection can be a risk factor for other systemic alterations including premature birth, cardiovascular illness and lung infections.

“The bacteria can establish themselves in other parts of the organism besides the mouth and set off a systemic reaction. However, these associations still have not been clearly demonstrated,” cautioned Feres.

In 2004, the researcher and her group participated in an international study that compared the microbiota of patients with periodontitis in Brazil, Chile, Sweden and the United States. The study showed that the composition of oral bacteria can vary between different countries.

“It is important that studies be carried out on the microbiota of patients with periodontitis in different geographic regions because this could result in specific treatments for each type of the disease in the future,” affirmed Feres.

The UnG researchers triaged patients for new studies on both periodontitis treatment and the treatment of peri-implantitis—an infection that occurs in the region surrounding dental implants.

The article “Short-term benefits of the adjunctive use of metronidazole plus amoxicillin in the microbial profile and in the clinical parameters of subjects with generalized aggressive periodontitis” (doi: 10.1111/j.1600-051X.2010.01538.x) by Feres and colleagues can be accessed at no charge on the Journal of Clinical Periodontology web site at: http://onlinelibrary.wiley.com/doi/10.1111/j.1600-051X.2010.01538.x/full.