X-ray Microtomography Evaluation of Mechanical vs. Chemo-mechanical Caries Removal

Methods: Five deciduous molars were sectioned in half along the middle of the open carious cavities. The two halves of each tooth were secured side by side, together with a 1mm Aluminium wire, on a kinematic stage and the whole sample was scanned using a high definition XMT at 30 microns resolution. After the initial scan, dentine caries was removed from one half of the sample by an experienced clinician using an excavator until the dentine “felt” hard (mechanical). Carisolv^™ was used to remove caries from the other half of the sample according to the manufacturer's instructions (chemo-mechanical). The sample was then re-positioned and re-scanned. Reconstructed XMT images of the two scans were evaluated to compare the two techniques.

Results: The XMT images showed a steep gradient at the boundary between sound and carious dentine. This gradient followed a decayed equation of C_m = a + b exp(-ad) where (C_m = mineral concentration, d = the distance from sound dentine, and a, b and a are constants). The region with the steep gradient remained after caries was removed using Carisolv^™ but this region was not detected after mechanical removal.

Conclusions: The chemo-mechanical technique appeared to retain a dentine layer that might correspond to affected, re-calcifiable dentine.