Different engagement of TLR2 and TLR4 in Porphyromonas gingivalis vs. ligature-induced periodontal bone loss

Abstract This study was conducted to investigate the roles of different Toll-like receptor (TLR) signaling in Porphyromonas gingivalis (P. gingivalis)-induced and ligature-induced experimental periodontal bone resorption in mice. Wild-type (WT), TLR2 knockout (KO), TLR4KO, and TLR2&4 KO mice with C57/BL6 background were divided into three groups: control, P. gingivalis infection, and ligation. Live P. gingivalis or silk ligatures were placed in the sulcus around maxillary second molars over a 2-week period. Images were captured by digital stereomicroscopy, and the bone resorption area was measured with ImageJ software. The protein expression level of gingival RANKL was measured by ELISA. The gingival mRNA levels of RANKL, IL-1β, TNF-α, and IL-10 were detected by RT-qPCR. The results showed that P. gingivalis induced significant periodontal bone resorption in WT mice and TLR2 KO mice but not in TLR4 KO mice or TLR2&4 KO mice. For all four types of mice, ligation induced significant bone loss compared with that in control groups, and this bone loss was significantly higher than that in the P. gingivalis infection group. RANKL protein expression was significantly increased in the ligation group compared with that in the control group for all four types of mice, and in the P. gingivalis infection group of WT, TLR2 KO, and TLR4 KO mice. Expression patterns of RANKL, IL-1β, TNF-α, and IL-10 mRNA were different in the P. gingivalis infection group and the ligation group in different types of mice. In summary, P. gingivalis-induced periodontal bone resorption is TLR4-dependent, whereas ligation-induced periodontal bone resorption is neither TLR2- nor TLR4-dependent.

Detection of odoriferous subgingival and tongue microbiota in diabetic and nondiabetic patients with oral malodor using polymerase chain reaction.

Background: Halitosis has been correlated with the concentration of volatile sulfur compounds (VSCs) produced in the oral cavity by metabolic activity of bacteria colonizing the periodontal pockets and the dorsum of the tongue. It has been assumed that there is a relationship between periodontal disease and diabetes mellitus. Objectives: The aim of the study was to assess the malodor using the organoleptic method and tanita device; to quantify odoriferous microorganisms of subgingival plaque and tongue coating, such as P. gingivalis (Pg), T. forsythia (Tf), and F. nucleatum (Fn) using polymerase chain reaction (PCR) in nondiabetic and diabetic chronic periodontitis patients. Patients and Methods: Thirty chronic periodontitis patients (with and without diabetes) with 5-7 mm pocket depth, radiographic evidence of bone loss, and presence of oral malodor participated in this study. Subjective assessment of mouth air was done organoleptically and by using a portable sulfide monitor. Tongue coating was also assessed. Results: The scores of plaque index, gingival index, gingival bleeding index, VSC levels, and tongue coating between the nondiabetic and diabetic patients were not significant (P>0.5). In nondiabetic patients, Fn was found to be significantly (P<0.5) more in tongue samples, whereas Pg and Tf have not shown significant values (P>0.5). In diabetic patients, Fn and Tf have shown significant (P<0.5) an increase in subgingival and tongue samples, respectively, whereas Pg has not shown significant difference between subgingival and tongue samples. Interpretation and Conclusion: The results confirm that there is no difference in clinical parameters between nondiabetic and diabetic periodontitis patients, but the odoriferous microbial profiles in tongue samples of diabetic patients were found to be high. However, there is a weak positive correlation between VSC levels, clinical parameters, and odoriferous microbial profiles.

Microbiology of peri-implant infections

The oral cavity has numerous microbes, providing us with a balanced microbial environment, however conditions like periodontitis sometimes prevail leading to bone loss and eventually causing tooth loss if not treated appropriately. By the same token,even with implants, gram positive facultative flora, establishes shortly after implant placement and stable implants showed no significant shifts in the composition, where as failing implants showed presence of Gram-negative anaerobic bacteria, particularly fusobacteria, spirochetes, and black-pigmenting organisms such as Prevotella intermedia. Which leads to destruction of the peri-implant apparatus and eventual loss of the implant if not attended to in a timely fashion. It is important to understand the microbiological aspects of peri-implant disease in order to proffer appropriate treatment