## 4 Discussion
### Probiotics in Periodontology
#### 4.2.2 Probiotics in Periodontitis
[PERSON] et al. [49] tested a subgingival combination of probiotics _Saccharomyces boulardii_ with a prebiotic (fructo-oligosaccharide) in patients with chronic periodontitis as adjuvant to SRP. Despite a short-term colonization by _Saccharomyces boulardii_ (until day 7), there was significant clinical improvement (as measured by the reduction of PI, GI, CAL, and PD) in the test group at 3 and 6 months after the mechanical treatment. The results suggest that _S. boulardii_ may be a good auxiliary agent in the treatment of chronic periodontitis. In a study by [PERSON] et al. [50], the effects of a probiotic combination were compared to the application of tetracycline fibers directly in the periodontal pocket after mechanical removal of the plaque. Use of probiotics caused a significant reduction of BOP and PD when compared to the tetracycline fibers. The combination of both approaches showed a significant improvement of BOP and PD when compared to tetracycline fibers alone illustrating the benefits of using tetracycline fibers and probiotics to treat periodontitis. [PERSON] et al. [51] tested _L. brevis_, with or without doxycycline, for the treatment of patients with aggressive periodontitis after mechanical plaque removal. After 2 weeks, there was a significantly higher reduction of PD in patients on _L. brevis_ and doxycycline relative to the other patients. At 2 months _Lactobacillus_ spp. count (CFU/mL) increased significantly in patients on _L. brevis_ and all patients had significantly improved clinical parameters when compared to baseline. In a study by [PERSON] et al. [52], the effects of daily administration of _Lactobacillus rhamosus_ SP1 or azithromycin tablets for 3 months were studied as an adjunct to SRP in patients with chronic periodontitis. Clinical and microbiological outcomes (as determined by the presence and levels of _Tannerella forsythia_, _Porphyromonas gingivalis_ and _Aggregatbacter actinomycetemcomitans_) improved over the study period but there were no significant differences between groups. [PERSON] et al. [53] compared the effects of consumption for 90 days of yogurt containing _L. rhamosus_ L820 with placebo yogurt in individuals with mental deficiency and periodontal disease. The PMA (papillary-marginal-attached) score was significantly reduced in the probiotic group at 90 days suggesting that _L. rhamosus_ L820 may have a beneficial effect on periodontal disease as an adjunct to mechanical oral hygiene. [PERSON] et al. [44] compared _L. reuteri_ with metronidazoleae as adjuvant to SRP in patients with chronic periodontitis. There was a significant improvement in the clinical parameters at all evaluation periods with no difference between groups, indicating that the efficacy of probiotic and antibiotic was similar. In a study by [PERSON] et al. [54], the use of _Streptococcus avalis_ KJ3, _Streptococcus uberis_ KJ2, and _Streptococcus rattus_ JH14 was not effective as adjunctive treatment of periodontitis despite lower PI at the end of the monitoring period (24 weeks) and the decrease of salivary _P. intermedia_ at 12 weeks. [PERSON] et al. [55] evaluated the efficacy of co-administration of doxycycline and symbiotic tablet (consisting of prebiotic _Streptococcus faecalis_ T-110 JPC and probiotics _Clostidium butyricum_ TO-A, _Bacillus mesenteric_ TO-A and _L. sporogenes_) as adjuvant to SRP in patients with periodontitis. Four weeks after the end of the intervention, a significant reduction of PD, CAL and BOP was observed in the test group indicating that this prebiotic-probiotic mixture can be a complement to the mechanical removal and doxycycline to improve clinical parameters, reduce bacterial load and repopulate the treated niche. Three different trials studied the impact of _L. reuteri_ in patients with chronic periodontitis using comparable study design (administration for 3 weeks of probiotic tablets containing _L. reuteri_ compared to placebo) and obtained similar results [5; 31; 56].