Characterization of biofilm and lesion on human root surface

Objectives: To study the effect of oral biofilm from salivary bacteria of caries-free and high caries risk patients and the lesion formed on human root surface.

Materials and Methods: Oral biofilms from salivary bacteria collected from high (DMFS = 6; n=3) and low caries risk (DMFS=0; n=3) patients was cultured in an artificial mouth for 7 days on 24 human root surfaces with or without 0.12% chlorhexidine gluconate (CHX). The biofilm was sampled daily for culture, identification and cloning and sequencing driven denaturing gradient gel electrophoresis (DGGE). The mineral changes of the human root surface substrates were studied with Fourier Transform Infra-Red Spectroscopy (FTIR). The changes of Type I collagen and chondroitin 4/6 sulfate on human root surface were studied with immunocytochemcial staining.

Results: The predominant bacteria increased in biodiversity when high caries risk oral biofilms developed from day 3 to 7. When CHX was used, the biodiversity of bacteria species reduced. The predominant bacteria were few when high caries risk oral biofilms developed after 7 day. The changes of collagen and chondrotin 4/6 sulfate were clearly labeled with immunocytochemical staining on root surface. There was significantly less damaged Type I collagen and chondroitin 4/6 sulfate on root surface in treatment than and non-treatment groups (p<0.05).Conclusions: The bio-diversity of salivary bacteria was suppressed by antimicrobial. The use of CHX reduce the cariogenicity of the biofilm microbiota on on human root surface.

The financial support from Johnson and Johnson (USA) and CRCG grant, HKU is gratefully acknowledged.