Analysis of resin tags formation in root canal dentine

Methods: Thirty extracted mandibular premolars were instrumented and fibre posts were inserted with three different adhesive systems with and without self cure activator: XP Bond, XP Bond/Self Cure Activator, AdheSE, AdheSE/AdheSE DC Activator, Hybrid Bond and Hybrid Bond/Hybrid Brushes. The resin tags were evaluated from slices obtained from sections perpendicular to the tooth's long axis at 3, 6, and 9 mm from the root apex under a Confocal Laser Scanning microscope. The general linear model procedure of SAS software was used to quantify the quality of the resin tags (p=0.005).

Results: In all groups lack of continuity of resin tags length, density and quality was observed not only from the cervical to the apical region of each root canal, but also in a mesio-distal direction to the long axis of the root. Application of etch & rinse XP Bond/Self Cure Activator in contrast to the one- and two-step self-etch adhesive systems provided the formation of the shorter, but considerably denser, more homogeneous and not interrupted resin tags with similar length.

Conclusions: None of the investigated adhesives were able to completely penetrate the dentinal tubules in the entire root canal. Use of the etch&rinse adhesive system and the activators for all types of adhesives significantly increased the density and the quality of resin tags.