AFM Observation Of Collapse And Expansion In Dentinal Collagen Fibrils

Methods: Twenty dentin disks with 2 mm thickness were harvested in midcoronal dentin of non-carious third molar using a diamond saw under water irrigation. Each dentin surface was sequentially wet ground  on 800-, 1000-, 1500- ,2000-,2500-and 3000-grit SiC polishing paper and ultrasonically cleaned in de-ionized water for 30 min. The half of each dentin disk was masked, while the other was applied with respective primer/etchant. Depth changes of the dentin surfaces with respect to the protected reference level in both dry and wet condition were observed and measured by AFM. One-way analysis of variance (ANOVA) was used to determine statistical differences in depth of demineralization depth between the groups.

Results: whether in dry or wet condition, the depths of demineralization using Clearfil SE Bond and iBond were significantly lower than those of 37% phosphoric acid and Super Bond C&B (p < 0.05).when in dry condition, the depth of demineralization caused by 37% phosphoric acid was significantly higher than that of Super Bond C&B (p < 0.05). In wet condition, the demineralized depth caused by Clearfil SE Bond was significantly lower than that of iBond (p < 0.05), while there was no significant difference of demineralized depth between 37% phosphoric acid and SuperBond C&B. Moreover, whatever the treatment agent is, the demineralized depth in dry condition was significant higher than in wet condition (p < 0.05).

Conclusions: The depth of demineralization and the extent of collagen network collapse in dry condition caused by total-etchants are higher than self-etching primer.

Funded by National Natural Science Foundation of China (30973350)