Controlled Caries Removal with a Novel Polymer Bur: TEM observation

Objectives: To evaluate the ultramorphology (TEM) of carious dentin surfaces prepared with an old and new versions of polymer burs designed for the self-limiting concept of caries removal.

Methods: Human carious teeth were sectioned into 2 mm thick slabs (n=12). Carious tissue was removed with either the old or new version of the polymer bur (SS White) according to the following protocols: utilization of polymer bur alone; polymer bur followed by rinsing with tap water; polymer bur followed by etching (37% phosphoric acid for 15 seconds) and rinsing (15s) steps. Slabs were fixed with Karnovsky's fixative, post-fixed with osmium tetroxide and embedded in epoxy resin. Undemineralized sections, 90-nm thick, were stained with uranyl acetate and lead citrate for TEM evaluation.

Results: TEM observation demonstrated the new polymer bur to be more effective than the previous version. However, some regions of dentin with bacteria present were still observed. Polymer bur application followed by etching and rinsing steps seemed to be more effective compared to utilization of polymer bur alone. Bacteria were more often observed on the prepared dentin surface than in dentin tubules.

Conclusion: The new version of the polymer bur with increased resin hardness was more effective in the removal of carious tissue. Less bacteria were observed whenever polymer bur was used followed by etching/rinsing procedures. Further evaluation is necessary for comparison of the effectiveness of this polymer bur with hand excavation and conventional rotary instruments.

This project was supported by SS White Burs, Inc.