Microbial Colonization of the Periodontal Pocket and its Significance for Periodontal Therapy
Multiple clinical trials have shown the efficacy of scaling and root planning as a treatment to reduce bacteria load in periodontally involved patients. In addition, some adjunctive antimicrobial protocols have been tested to determine if there is more control of bacteria load. A review published February 2018 in Periodontology 2000 reassessed previous studies and strategies for periodontal therapy from the perspective of the disease being a consequence of microbial colonization.1
The first topic covered in this review focused on “Microbial colonization of the gingival crevice and its consequences”. The author reviewed several studies, two that were very telling involved cessation of oral hygiene in young volunteers with healthy gingiva. As soon as inflammation was evident, the volunteers were given specific oral hygiene instructions. In this study, clinical signs of gingivitis were evident within 9-21 days after cessation of oral hygiene. However, when bacterial deposits were removed through proper hygiene techniques, the inflammation subsided.
This exact experiment was done 20 years later at the same institution. This follow up study found that the association between plaque accumulation and gingivitis was not significant. Though interindividual variations in gingival inflammation were noted in the previous study, those variations were thought to be related to quantitative differences in plaque mass or microbial composition. Yet these variations have been observed in the absence of notable differences in plaque accumulation.
This indicates that there are factors at play specific to the host. Such factors that have been indicated in the interindividual variation of plaque-induced inflammation and microbial composition include differences in systemic and local inflammatory response as well as environmental factors.
The second section focused on “Microbial colonization and periodontal pocket formation”. In a study assessing microbial changes associated with puberty gingivitis, the authors discovered microbiological changes in the crevicular microbiota of the individuals in the study prior to and after the onset of puberty gingivitis. Such changes that were indicated included an increased number of Capncytophaga spp., preceded the onset and an increase in Prevotella spp., which was observed with increased bleeding.
These same individuals were reassessed 6 years later, the parameters assessed included periodontal and microbiological status. The results showed individuals with increased bleeding during puberty differed from individuals without puberty gingivitis. These differences included significantly higher gingival bleeding, increased sites of >3mm of attachment loss, and presence of spirochetes.
It has long been believed that gingivitis progresses to periodontal disease when complex bacterial interaction overload host resistance. However, in the case of refractory peri-implant infections induced by persistent luting cement, it is evident that anaerobic infections can be induced and sustained by a foreign body.
In a classical bacterial infection, the diversity of the microbiota decreases making culturing to find the bacteria causing the infection easy to recognize and treat accordingly. However, in most cases of periodontal disease, the diversity of the microbiota increases as the disease develops.
Understanding the remarkably diverse microbiota associated with periodontal disease, targeting a single species of bacterium seems too simplistic. The use of a combination of amoxicillin and metronidazole has been studied repeatedly. It has been shown effective at suppressing A. acitnomycetemcomitans and is often used to treat advanced or aggressive periodontitis.
Another option utilized is local therapy, placing antimicrobial agent sub-gingival. This option offers the ability to use concentrations that could not be reached through systemic administration. Several studies have evaluated the effectiveness when compared to systemic antibiotic treatment. In one study it was determined there was no significant difference between using an adjunctive treatment of amoxicillin/clavulanic acid or tetracycline delivered locally after scaling and root planing.
In another similar study, the use of adjunctive systemic amoxicillin and metronidazole was more effective than placement of chlorhexidine chip after scaling and root planing. The author notes “the evidence for an advantage of bacteriology-assisted clinical protocols are unsatisfactory”.
Microbiological sampling, over time, has shown a microbiota like that found before any periodontal therapy may re-emerge. Studies have indicated that periodontal bacteria can be distributed throughout the entire mouth, including the dorsal surface of the tongue and the crypts of the tonsils. These areas that harbor periodontal bacteria may be the source of recontamination after periodontal therapy.
The value of microbiological tests after periodontal therapy is unclear and arguable in predicting future recolonization and stability after therapy. A longitudinal study showed limited potential to predict clinical outcomes 6 months later. However, these tests did show the importance of good oral hygiene when done before therapy and after therapy and may be a good teaching tool.
The author’s conclusion as it applies to microbial recolonization after therapy states, “Treated sites are subject to recolonization with microbiota similar to that present before therapy. The degree and speed of recolonization depend on the treatment protocol, the distribution patterns of periodontal microorganisms elsewhere in the oral cavity and the quality of the patient’s oral hygiene.”
In some cases, subgingival bacteria may not mineralize between maintenance visits, this opens the door to use less aggressive methods for biofilm control. One such suggested method is air abrasion with glycine powder. This technique has been shown as effective and well accepted by patients. Patients also report less discomfort than with ultrasonic scaling. One study evaluating the efficacy of glycine powder found beneficial shifts in the composition of the subgingival microbiota in moderate to deep periodontal pockets.
The author’s overall conclusion states. “little evidence supports microbiological testing as an approach to obtain better clinical outcomes. At present, there exists no protocol with proven superiority, in terms of efficiency or effectiveness over scaling and root planing plus systemic amoxicillin and metronidazole, for the therapy of any form of periodontal disease. Nevertheless, to limit the use and potential overuse of antibiotics, the search for alternatives must continue, and further efforts must be made to find optimal treatment protocols for all possible clinical conditions. Routine prescription of antibiotics for mild to moderate periodontitis is not recommended as these conditions, in general, respond sufficiently well to scaling and root planing alone.”
Do you currently use microbiological testing in your office? Have you found it beneficial in any capacity? Do you extensively use adjunctive local therapy? If so, what local therapy have you found most effective?
- Mombelli A. Microbial colonization of the periodontal pocket and its significance for periodontal therapy. Periodontol 2000. 2018;76(1):85‐96. doi:10.1111/prd.12147
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