Analysis of resin tags formation in root canal dentine: a cross sectional study

To evaluate the length, density and quality of resin tags formed by penetration of various types of adhesive systems into dentinal tubules at various cross section levels of the root canal in correlation to the density of dentinal tubules.

Thirty mandibular premolars were instrumented and fibre posts were inserted with three different adhesive systems with and without activator: etch & rinse XP Bond and XP Bond/Self Cure Activator; self-etch (two-step) AdheSE and AdheSE/AdheSE DC Activator and self-etch (one-step) Hybrid Bond and Hybrid Bond/Hybrid Brushes. The resin tags were evaluated from slices obtained from sections perpendicular to the long axis of the teeth at 3, 6, and 9 mm from the root apex under a Confocal Laser Scanning microscope.

In all groups, lack of continuity of resin tag 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 adhesive in contrast to the self-etch adhesives provided the formation of the shorter, but considerably denser, more homogeneous and not interrupted resin tags with similar length. Use of the activator for all types of adhesives significantly increased the completeness (P = 0.014) and continuity (P = 0.024) of resin tags.

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