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It is well understood that diseases of the periodontium are bacterial in nature, and that it is the introduction of disease-producing bacteria that begins the cascade of the inflammatory host response. Periodontitis is considered the second most frequent modifiable inflammatory condition. However, despite the modifiable nature of periodontitis, as well as the sophistication of dental research and the advancement of implementation strategies in clinical practice, the prevalence of periodontitis continues to remain high.1
While hundreds of microorganisms have been documented as components of the oral cavity, it is the delicate balance of these microorganisms that critically determines the onset, or stabilization, of diseases. This article critically examines the root cause of the delicate shift from health to disease of the periodontium, dental clinicians' role in mitigating this shift, and the integration of probiotics containing L. reuteri for optimal patient outcomes.
Biofilm and Oral Disease
For over a century, dental professionals have been widely trained that disruption of biofilm is required to manage oral diseases. It is through this theory that dental practitioners across the United States and around the world are trained in critical hand skills focusing on complete debridement of biofilm.
The complication, however, arises in the overt resilience of the microorganisms of the oral cavity to readily rebuild. Within minutes of a professional debridement or personal oral hygiene routine, the acquired pellicle begins to form on the naked enamel. This formation is critical, as the acquired pellicle is protective in nature and provides a slime barrier for the enamel against acid attack.2
Without hesitation, early colonizers begin to attach to the acquired pellicle. In this stage, early colonizers are classified as green-complex bacteria and are associated with health. Primarily Streptococcal in nature, health-producing bacteria such as S. mitis, S. oralis, and S. sanguis readily colonize and offer a symbiotic or healthy environment.3 If well maintained through oral hygiene habits, the oral cavity can remain well-balanced in a symbiotic state of health, and it is believed that achieving a state of symbiosis in the oral cavity is the true objective for dental professionals in treating dental patients with overt oral disease.
The Onset of Periodontal Diseases
If left undisturbed, the initially healthy biofilm matrix will become an attractive host for bacteria with greater complexities. The invasion of the Actinomyces species begins the early transition from a periodontium in a state of health to that of gingivitis.4 Defined as a nonspecific inflammatory condition of the gingiva, gingivitis is observed clinically as the host response to an accumulation of disease-capable bacteria with byproducts that are equally as disease-capable.
It is critical to note that the onset of gingivitis begins via dysbiosis, or an interruption in the delicate symbiotic balance of a previously healthy periodontium.5 As disease-producing bacteria increase in numbers and eventually predominate the oral cavity, the once-balanced periodontium experiences a dysbiotic state. In dysbiosis, the outnumbered health-producing bacteria are diminished, thus permitting an acceleration of the disease process.
If the periodontium remains in a pervasive state of dysbiosis, there is an increased risk of disease spreading from the gingival sulcus into the underlying connective tissue and eventually leading to a risk of clinical attachment loss and subsequent spread of the disease into the underlying bone, as observed in periodontitis.6
The Root Cause
It is well understood that diseases of the periodontium occur through a series of coordinated efforts by pathogenic bacteria. In turn, dental professionals have received advanced training in debridement techniques and continue to foster complex conversations with their patients about the critical nature of optimal personal oral hygiene habits for improved health.
Rather than establishing symbiosis once again, institutionalized training has offered a solution of complete demolition of the entirety of the biofilm matrix as a means of disrupting the microbiota. This strategy requires prudent attention to scheduled dental visits, high-level hand skills for treating clinicians, and aggressive patient-applied oral hygiene routines scheduled at ideal frequencies to continue destroying the entirety of the biofilm matrix.
The root cause of oral disease, however, is not simply the development of biofilm but rather the dysbiosis affiliated with the predominance of disease-producing bacteria. Therefore, treatment strategies aimed at maintaining a roster of predominantly health-producing bacteria may provide an adjunctive approach to stabilizing health within the oral cavity.
Probiotics and Biofilm
Probiotics are defined by the Food and Agricultural Organization (FAO) of the United Nations and the World Health Organization (WHO) as "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host."7 While consumers have many options when it comes to the selection of an ideal probiotic to meet their needs, probiotics containing high strains of L. reuteri have demonstrated optimal abilities to stabilize the microbiota of the oral cavity.8
One critical aspect of L. reuteri is its ability to compete with the attachment mechanism of common disease-producing bacteria. Due to the competitive nature of L. reuteri within the oral cavity, plaque indices decline without the use of traditional methods of plaque disruption, such as toothbrushing, interdental care, and mouth rinsing, to name a few. In turn, a research study concluded that L. reuteriusers experienced a 71% reduction in moderate to severe plaque conditions when compared with a placebo group.9
Another critical property of L. reuteri is its ability to colonize biofilms within the oral cavity. As strains of L. reutericolonize the biofilm, saliva, and oral mucosa, it reintroduces-or introduces, in the cases of patients completely devoid of L. reuteri-health-producing bacteria into the oral cavity. While this may appear counter-intuitive for dental professionals trained in plaque disruption, the action of colonizing plaque with L. reuteri renders the biofilm dense with bacteria capable of creating a symbiotic environment.
Probiotics and Gingivitis
The competitive nature of L. reuteriwithin biofilm of the oral cavity has its benefits in addressing inflammation of the gingiva. As such, patients placed on
L. reuteri strains for active gingivitis experienced an 85% reduction in bleeding upon probing scores and a four times reduction in gingival inflammation.9
The positive results of probiotics containing L. reuteriwere further examined in a randomized placebo-controlled research study of a group of sailors isolated at sea. Within this study, baseline bleeding upon probing scores were gathered and the subjects were not provided oral hygiene instructions of any kind, but rather were instructed to take either a probiotic containing L. reuterior a placebo. The sailors returned after 42 days at sea, and bleeding upon probing scores at the conclusion of the study were compared to that of their baseline.10
It is quite common to observe an increase in bleeding scores over the several weeks at sea, which was observed in the placebo group. However, the group receiving probiotics containing
L. reuteridemonstrated a steady and dramatic decline in bleeding upon probing scores throughout the study. This study offers promising details regarding the adjunctive use of probiotics containing L. reuteriin the control of gingivitis despite a lack of optimal oral hygiene.10
Probiotics and Periodontitis
The advancement of diseases of the periodontium from gingivitis to periodontitis involves the sophistication of pathogenic bacteria capable of destruction, complexities around pocket formation associated with clinical attachment loss, acceleration of local and systemic inflammatory conditions, and subsequent impact on the resilience of the alveolar bone. As such, management of periodontitis requires a care plan of various modalities aimed to target the myriad of destructive elements associated with periodontitis.
A critical step in the management of periodontitis is the swift reduction in periodontal pathogens. While professional debridements and personal oral hygiene habits may disrupt biofilm, it is well understood that complexities of advanced root anatomy, unique anatomical architecture, and advanced periodontal pockets may complicate the ability to access and effectively disrupt biofilm in many periodontal cases. The use of probiotics containing L. reuterihas demonstrated optimal outcomes in lowering concentrations of common pathogenic bacterial strains such as Prevotella intermedia, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitansby 90%.11 The reduced pathogenic bacterial load, in turn, reduces concentrations of inflammatory cytokines, particularly TNF-alpha, IL-1, and IL-7 within the gingival crevicular fluid.12
As a result of decreased pathogenic bacterial and subsequent inflammatory cytokine concentrations, patients taking probiotics containing L. reuteri as an adjunct to periodontal treatment demonstrated a statistically significant reduction of periodontal pocket depths observed six months following treatment. It is critical to note that the efficacy of probiotic strains of L. reuteri were particularly optimal in patients with advanced periodontal pocket depths, as periodontal cases with moderate and advanced pocket depth readings of 7 mm or more responded favorably to the use of probiotic therapy. These results are also readily observed in improved plaque indices, gingival indices, bleeding indices, pocket depth, and clinical attachment levels in patients who were non-responders to scaling and root planing.13
Finally, patients taking probiotics containing L. reu-teri demonstrated an improved clinical attachment level gain by 54% when compared with the placebo group and experienced a significantly reduced demonstration of bone loss when compared with placebo.11 The significantly less bone loss observed in patients taking probiotics containing L. reuteri as an adjunct to scaling and root planing demonstrates improved treatment outcomes and thus indicates 47% less periodontal sites in need of surgery when compared with the placebo group.11
The critical study of the root cause of oral disease continues to leverage research while scrutinizing the current "gold standard" protocols for accuracy, efficacy, and outcomes. Within this framework, the importance of re-establishing and maintaining a symbiotic environment within the oral cavity must be understood along with the role that probiotics containing L. reuterican play in preventing and treating diseases of the periodontium, although the Food and Drug Administration has yet to evaluate its efficacy.
As treatment paradigms begin to shift, current research offers a promising adjunct for the management of patients experiencing heavy concentrations of plaque biofilm, clinical signs of gingivitis, and overt observations of periodontitis. The existing research and current available modalities now support the integration of L. reuteri strain-specific probiotics into periodontal protocols and programs.
About the Author
Katrina M. Sanders, RDH, BSDH, MEd, RF
Founder, CEO, and Keynote Speaker
Sanders Board Preparatory
Clinical Liaison of Hygiene Excellence & Innovation
The author has received honoraria from BioGaia for lectures and articles.
Queries to the authors regarding this course may be submitted to email@example.com.
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