Microscopic study of cultural and diffusion kinetics of the effects of a prototype extracellular matrix on the photodynamic therapy of periopathogenic bacteria - a pilot study.

INTRODUCTION: In dental medicine, photodynamic therapy is a promising treatment for bacterial infections. Oral biofilms, on the other hand, can produce an extracellular matrix that provides protection and stability against external forces.

Probiotic candidates among dairy Lactobacilli and Streptococcus thermophiles strains for control of the oral pathogen Porphyromonas gingivalis.

INTRODUCTION: The gram-negative bacterium Porphyromonas gingivalis is a major causative agent of periodontitis in adults. It is also associated with disorders of the cardiovascular and endocrine systems, rheumatoid arthritis, pancreatic cancer, and Alzheimer's disease. Lactic acid bacteria (LAB) present in the oral cavity or introduced as probiotic preparations can support successful treatment of periodontitis due to their antagonism with the pathogen. AIM: The aim of this study was in vitro assessment of the antimicrobial activity of Lactobacillus spp. and Streptococcus thermophilus against P. gingivalis. MATERIALS AND METHODS: The antimicrobial effect of lactobacilli or S. thermophilus from the LBB Culture collection against P. gingivalis DSM 20709 was evaluated with the well diffusion assay on Wilkins Chalgren blood agar. Inhibition of the pathogen was evaluated by measuring the diameter of clear zones around the wells. RESULTS: Application of milk fermented with selected LAB resulted in а bacteriostatic effect. The most active culture was S. thermophilus 187/4, followed by L. delbr. ssp. bulgaricus (LBB.B1054, C3/2 and LBB.B120), L. helveticus LBB.H48/1 and L. rhamnosus I-1/13. The respective reconstituted freeze-dried preparations had a stronger inhibitory effect on the pathogen with the formation of clear bactericidal zones. The effect of milk acidified with lactic acid was apparent with minimal bactericidal zone observed at concentration of 0.1%. The effectiveness of the assay was confirmed with Elgydium and Eludril. CONCLUSIONS: P. gingivalis DSM 20709 was sensitive to the metabolites produced in fermented milk by selected strains of L. delbr. ssp. bulgaricus, L. helveticus, L. rhamnosus, and S. thermophilus. Reconstituted freeze dried fermented milk had а stronger inhibitory effect compared to fresh samples. Lactic acid produced by lactic acid bacteria was the key component for inhibition of the pathogen.

In Vivo Collection and SEM Identification of Oral Biofilm Using Indirect Composite Prototype Restorations. Clinical and Laboratory Study.

BACKGROUND: The oral ecosystem is a dynamic environment inhabited by more than 700 microbial taxa. Recent studies report that multispecies oral biofilms develop on the surface of resin composites leading to degradation of its organic matrix and altered structural stability of the restoration. AIM: To examine the efficacy of a novel clinical approach to investigating in vivo formed biofilms on resin composite surfaces. MATERIALS AND METHODS: The clinical protocol of this study implemented indirect composite molar restorations (from resin material Filtek Z250, 3M ESPE) as intraoral biofilm carriers (test devices). We recruited for the experiment 5 consenting adult subjects with indications for indirect molar restoration. For each subject we fabricated 4 indirect restorations, 3 of which dedicated to different intraoral duration - 3, 7, and 14 days. All composite carriers were fixed temporarily for the intended time period and consecutively replaced. The detached carriers were prepared for microscope analysis at each time interval. The fourth composite carrier was used as the definitive restoration. RESULTS: The timeline of the biofilm formation and the microbial morphology were associated with previous studies of in vivo bacterial colonisation. A correlation between the plaque formation cycle and the DMFt indices of the subjects was established. CONCLUSIONS: The implementation of indirect composite restorations as intraoral biofilm carrier offers valuable contribution to the real time investigation of in vivo biofilm accumulation.