Can the size and the luting material influence in the bond strength of the fiberglass post to dentin?

Objective: to evaluate the influence of lengths and different luting agents on bond strength of fiberglass posts to dentin.   Material and Methods: Sixty single-root bovine teeth were endodontically treated and included in polyether and acrilyc resin to simulate a periodontal ligament. They were divided into 6 groups according the post lengths (6, 10 or 14 mm) and luting agents (self-adhesive dual resin cement – U; or etch-and-rinse dual resin cement – A): U6, U10, U14, A6, A19 and A14. All fiberglass posts were cemented as the manufacturer's recommended. After this, mechanical aging was performed (1.2x106 cycles; 4 Hz, 90 N). Then, push-out specimens were conducted (2.0 ± 0.1 mm), being the test executed in a universal machine (10 kgf at 0.5 mm/min). Data obtained were submitted to Kruskal-Wallis and Dunn's test.   Results: there was no statistically difference on bond strength between the groups due to the type of luting agent (p> 0,05). However, the post length factor isolated showed significantly different results for the U groups (p < 0,05). The U10 group showed similar union values to U6, but statistically inferior to U14.   Conclusion: bond strength of fiberglass posts of the same length to dentin did not present differences according the luting agent, but the post length property influenced when self-adhesive resin cement was used.