Biofilm morphology in the transition zone of combined endo-perio lesions

Objectives: Evaluation of the biofilm morphology in the transition zone between apical lesions and periodontal pockets in combined endo-perio lesions with a modified protocole involving a simplified histologic sample preparation and a low-vacuum SEM examination method. Methods: 21 teeth with combined endo-perio lesions, extracted and washed with saline, underwent fixation in modified Karnovsky solution and dehydration in alcohol series. The transition zone between the apical lesion and the periodontal pocket was located and examined under low-vacuum SEM (INSPECT S,FEI,Hillsboro,OR,USA), at 80-250Pa and 15kV. Presence of established biofilm, isolated glycocalyx, isolated bacteria, nude cement areas, periodontal fibers, resorbtion areas, calculus, unstructured debris, and the type of microorganisms (cocci, rods, filaments, spirils) was assessed, results were quantified and expressed as percentage. Correlations were established between characteristics using the Spearman correlative analysis. Results:Low-vacuum inspection resulted in electrical charge-free images of the non-conductive or contaminated biofilm-covered surfaces. The transition zones displayed established biofilms in 38%, isolated glycocalix strands in 9.5%, resorbtive areas in 28.5%, scattered bacteria in 24%, nude cement areas in 71%, calculus deposits in 24%, debris in 28.5%, and periodontal fibers in various degrees of distruction in 24% of the samples, respectively. Coccii were in 57%, bacilli 14%, and filaments in 24% of the samples, and no spirils. Significant strong positive correlations were between presence of cocci and established biofilm (rho=0.84, p<0.01), between presence of rods and cemental resorbtions (rho=0.68, p<0.01) and between filaments and cemental resorbtions (rho=0.48, p<0.5), respectively. Conclusion: The transition zone in combined endo-perio lesions displays a relatively low incidence of established biofilm presence. Coccoid forms were predominant, while bacilli and filaments were rather rare. Resorbtive lacunae appeared in one third of the samples. The low-vacuum SEM method is simple, cost-saving, results in excellent biofilm images, avoids sputtering and destruction of the biologic samples and electrostatic charges.