Method: Root canal models were prepared from transparent silicon rubber and consisted of a main canal (20 x 1.5 x 0.5 mm) and a side canal (10 mmx 0.2 mm) situated 3 mm from the apex of the main canal. A model system was built around Serratia NCIMB40259, a non-pathogenic gram-negative bacteria, which can enzymically catalyse hydroxyapatite formation around the bacterial cells attached to the surface under study and forms calculus on teeth.
Result: Scanning electron microscopy showed that the bacteria were present in the coronal and apical parts of the tooth canal model, independent of the canal diameter. Although the side canal was much narrower it was also occupied by bacteria. EDX analysis undertaken after the mineralization process showed the formation of a calcium phosphate crystalline deposit inside the root canal.
Conclusion: Serratia biofilms are easy to grow inside the root canal model and mineralisation is readily achieved making it an ideal model system for studying the biofilm and calculus formation and removal from inaccessible places. In future studies, the biofilm adherence will be assessed and its removal by ultrasonic dental instruments will be quantified using micro-CT imaging.