Periodontitis is a chronic inflammatory lesion that initiates plaque. For the pathogenic mechanism of plaque biofilms, scholars have mainly put forward the theory of non-specific plaque and the theory of specific plaque. In recent years, it has been found that periodontal microbiota imbalance may be another important factor in the occurrence and development of periodontitis. Periodontitis is mainly treated with mechanical removal of subgingival plaque biofilm, combined with topical or systemic adjuvant drugs.
However, the anatomy of the periodontal period makes it difficult to reach with mechanical therapy, and the frequent colonization of periodontal pathogens in the oral cavity may be related to the poor response of some severe and difficult periodontal diseases. Probiotics are defined as "living microorganisms that are used in sufficient quantities in the host body and are beneficial to the health of the host".
Probiotic therapy refers to the method of replacing pathogenic microorganisms with probiotics to regulate the microecological balance, which was initially used to prevent and treat dysbiosis of the digestive system, and gradually applied to the oral periodontal field.
1. Research on the application of probiotic preparations in the clinical practice of periodontal disease
There are many types of probiotics, and there are two main categories of probiotics used to assist in the treatment of oral diseases. The first type is probiotic strains isolated from healthy people, such as Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus rhamnosus, etc., which have been widely used in the treatment of digestive tract diseases, and have been proven to have antibacterial and anti-inflammatory effects. The other type is specific probiotic strains isolated from the oral cavity, such as Streptococcus salivarius K12, Streptococcus salivarius M18, etc.
1. Periodontitis
Several studies have shown that adjunctive application of probiotic preparations after mechanical plaque removal of the whole mouth may improve periodontal clinical markers. Thirty patients with moderate to severe periodontitis were divided into two groups according to the randomized control principle, one group was treated with SRP followed by adjuvant application of Lactobacillus reus, and the other group was treated with oral placebo tablets after SRP as a control.
The results showed that the proportion of bleeding sites, the depth of probing and the plaque index were significantly reduced in the probiotics group at each time of follow-up, and the gingival inflammation index showed a stronger improvement effect than the subgingival scaling and root planing treatment alone, and the clinical attachment level was also higher than that of the mechanical treatment group alone at 3, 6 and 12 months of follow-up, and the difference was statistically significant.
The same results were obtained from the changes in PI, GI, BOP, PD and CAL at baseline and 21, 90, 180, and 360 days after treatment in 40 patients with chronic periodontitis. However, although the adjuvant application of probiotic preparations after full-mouth SRP treatment could significantly improve the relevant clinical indicators, there was no significant difference in the effect of mechanical therapy alone.
A total of 30 patients with moderate to severe chronic periodontitis were randomly divided into two groups, the experimental group and the control group, and were given Lactobacillus reuteri tablets and placebo tablets, respectively.
Subsequently, the investigators further evaluated the different depths of the periodontal pocket and the improvement effect of PD and CAL, and found that the PD and CAL values of the experimental group with different needle depths were lower than those of the control group after treatment, but there was still no statistical difference between the groups.
In addition, chlorhexidine fungicide was also applied after SRP treatment in this experiment, which may destroy the homeostasis of the periodontal microbial community to a certain extent during bacteriostatic treatment, which is not conducive to the recovery of periodontal tissue, thus affecting the final treatment effect.
A study was carried out on the adjuvant application of probiotics in patients with periodontitis who had a long-term smoking Xi habit, and 34 subjects were randomly divided into two groups after full-mouth SRP treatment, one group took Lactobacillus reuteri lozenges, and the other group took placebo as a control for 21 days, and the changes in the levels of PD and CAL and the proportion of periodontal pockets and BOP sites with PD≥5mm and bleeding accompanied by probing bleeding were compared between the two groups before treatment and 3 months after treatment.
In this study, the reduction degree of PD in deep periodontal pockets was significantly greater than that of the above levels, suggesting that probiotic-assisted SRP treatment had more advantages in reducing PD in deep periodontal pockets, which may be because the number of pathogenic bacteria associated with periodontitis increased with the increase of periodontal pocket depth, and probiotics could inhibit the adhesion and colonization of these pathogenic bacteria, and the effect was good.
In this experiment, the PD of the medium-depth periodontal pocket was not significantly reduced, and there was no statistically significant change in the CAL level of the whole and different bag depths, which may be related to the smoking, and some studies have shown that the number of periodontal ligament fibroblasts in smoking patients decreased sharply, and the intra-pocket epithelium keratinization hyperplasia, combined with the epithelium is difficult to form reattachment, which delays the recovery of deep periodontal pockets.
Secondly, the restoration of periodontal tissue is a slow and long-term process, and no significant improvement in the level of attachment may be observed in the short term.
2. Gingivitis
The effectiveness of probiotic preparations in improving gum inflammation varies among different populations. The application of Lactobacillus reuteri in patients with gingivitis without systemic disease could not improve PI and GI. Probiotic lozenges containing Lactobacillus plantaris, Lactobacillus breve and Pediococcus lactis assisted in professional mechanical plaque removal, and there was no significant improvement in gum inflammation after 6 weeks.
A study of gingivitis cases with type 2 diabetes mellitus found that after randomization after oral hygiene education only, Lactobacillus reuteri and placebo were given respectively, and after 30 days, it was found that the improvement effect of PI and BOP in the probiotic group was better than that of the control group.
Some researchers also applied Lactobacillus reuteri to women with gingivitis in the second trimester of pregnancy, and found that the average levels of GI and PI in the two days after the end of pregnancy were significantly improved compared with those before treatment.
Differences in the results of the analysis may be due to different study subjects, different degrees of gingival inflammation, and different responses to the action of probiotics. Due to the influence of systemic factors, the serum level of pro-inflammatory factors in diabetic patients is higher than that of systemically healthy patients, which induces aggravation of local gingival inflammation, while gingivitis in pregnant women also shows more severe gingival inflammation due to the dual effects of hormones and pro-inflammatory factors.
The more severe gingivitis, the corresponding increase in the composition and quantity of microorganisms in the local environment, probiotics can quickly reduce the ecological stability of microbial flora by changing the composition of pathogenic microorganisms, and the treatment effect is more obvious.
Second, the mechanism of action
1. Affect the plaque biofilm microecology
Periodontal disease is caused by the excessive increase of periodontitis-related pathogenic bacteria, the disruption of normal and stable interactions between microorganisms in the local environment, and the imbalance of periodontal microecology.
Some researchers have found that the bacterium can copolymerize with periodontal-related pathogens in the study of periodontal related pathogens, adhere to epithelial cells, invade epithelial cells, and induce host immune response, which plays an important role in the progression of periodontitis, and its excessive increase in subgingival abundance may cause dysbiosis of the subgingival microenvironment.
Probiotics can exert their probiotic effect by regulating the interaction of microorganisms in the biofilm and changing the local microenvironment of microbial survival.
(1) Improve the composition of microorganisms in plaque biofilms
Probiotics can reduce the number of periodontal pathogenic bacteria in the biofilm, increase the proportion of oral health commensal bacteria, regulate the proportion of microorganisms in the biofilm, correct the imbalance of microflora, and promote the recovery of periodontal inflammation. Several studies have found that the number of Pg, Fn, Actinobacillus actinobacillus concomitant and Prevonella intermediates decreased significantly when the number of specific periodontal pathogens changed after adjuvant application of Lactobacillus or Bifidobacterium after mechanical therapy.
This inhibition of periodontal pathogenic bacteria may involve the following mechanisms: probiotics copolymerize with pathogenic bacteria, which directly prevents the adhesion and proliferation of periodontal cells by pathogenic bacteria, and produces nitric oxide and bacteriostatic products to block the expression of virulence factors related to pathogenic bacteria, thereby inhibiting their growth and reproduction.
- Improve the plaque biofilm environment
Organic acids such as lactic acid and acetic acid produced during the metabolic activities of probiotics will reduce the pH value of the microbial living environment and prevent periodontal pathogenic bacteria from reintegrating in the biofilm. Some scholars have also found that Bifidobacterium lactis can regulate macrophages to produce reactive oxygen species, transform anaerobic environment into aerobic, which is conducive to the growth of oral health-related microorganisms and achieves the purpose of regulating the microecological balance of microflora.
2. Regulate the immune inflammatory response of the periodontal microenvironment
The immune response to host-microbial interaction indirectly triggers periodontal tissue inflammation. After SRP treatment, the adjuvant application of probiotics can upregulate the anti-inflammatory mediators in gingival crevicular fluid and saliva of patients with periodontitis, reduce pro-inflammatory factors, regulate the local immune inflammatory response of periodontal, and then control local inflammation and promote tissue healing.
This antibody component can neutralize pathogens, prevent periodontal pathogens from adhesion and invasion of epithelial cells, and further inhibit periodontal pathogens. In addition, it has been found that Lactobacillus can reduce the number of Th17 regulatory cells, inhibit their production of a large number of pro-inflammatory factors, and prevent further destruction of periodontal tissue.
The regulation of host immune response by probiotics is species-specific, and different probiotic species have certain differences in the immune regulation of the body, and the related mechanisms need to be further studied to clarify the relevant immunomodulatory mechanisms when specific bacteria exert probiotic effects.
3. Safety issues of probiotic preparations
When probiotic preparations enter the human body as live bacteria, there may be a series of systemic risks: for patients with compromised or incomplete immune systems, the risk of bacteremia is higher, and they are also susceptible to excessive immune stimulation.
Probiotics may degrade the mucin of gastrointestinal epithelial cells as they pass through the gastrointestinal tract, leading to gastrointestinal disorders. Some studies have found that some lactic acid bacteria and other probiotics undergo the transfer of drug resistance genes between probiotics and pathogenic bacteria during microbial culture. For oral tracts, certain lactic acid bacteria and bifidobacteria have been documented to pose a cariogenic risk.
Probiotics have the specificity of strains, and the effects of different strains on the oral cavity or the whole body are not the same, and their safety has a certain relationship with the objects and methods of application, which need to be explored in depth. The safety of probiotic preparations can be improved by the application of inactivated probiotic preparations.
Live probiotics often have the potential to invade the host and are antibiotic resistant, and inactivated probiotics can overcome these limitations. It is suggested that inactivated probiotics may exert similar probiotic effects to live bacteria and have a higher safety profile.
In the future, more systematic studies are needed to clarify the mechanism of probiotics affecting the periodontal microbiota, the optimal strains, ideal concentrations, ingestion frequencies and more effective intake methods, so as to provide a more reliable theoretical basis for clinical application.
epilogue
In summary, the adjuvant application of probiotics after basic periodontal treatment significantly improved the clinical effect of basic periodontal treatment alone. This provides a new idea and a new option for the adjuvant treatment of periodontitis.
It is suggested that probiotic preparations can be used as an adjunct after basic treatment for patients with periodontitis to control inflammation, prevent progressive destruction of periodontal tissue, promote the healing of periodontal tissue, and improve the clinical treatment effect by inhibiting periodontal pathogenic bacteria and regulating the body's immune inflammatory response.
The 6-month follow-up of this study showed no effect of probiotics on alveolar bone height and density, and the follow-up time should be extended in the future, and the change trend of alveolar bone height and density of patients should be closely tracked, so as to provide more comprehensive data support for the efficacy of probiotics in the adjuvant treatment of periodontitis.
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