OBJECTIVETo investigate the correlation of morphological characteristics and failure modes of two types of glass-fiber posts luted with self-adhesive resin cement and etch-and-rinse adhesive system.

METHODSThirty-six intact single-rooted premolars were collected and removed the crown. After root canal therapy, teeth were randomly divided into 4 groups. Group A: Self-adhesive with POPO fiber post. Group B: Etch-and-rinse with POPO fiber posts. Group C: Self-adhesive with Para Post. Group D: Etch-and-rinse with Para Post. Each root was sectioned into six 1 mm-thick serial slices and a push-out test was performed. The dentin-cement-post adhesive interface of each specimen and failure modes after fracture were evaluated by stereomicroscope observation.

RESULTSInterface morphology observe indicated that voids present in group B (64.2%) and D (66.7%) were significantly higher than group A (5.8%) and C (13.7%) (P < 0.001). Interface gaps appeared at the resin-dentine interface in group D (41.2%) were significantly higher than group A (13.5%) and C (11.8%) (P < 0.0083), and the failure modes in each group were significantly different (P < 0.0083) except for group A and B (P = 0.69).

CONCLUSIONVoids present in cement layer were associated with the luting agent involved. Morphological characteristics of the fiber post-resin luting agent-root dentin adhesive interface were discrepant with failure modes in different root region. There were interaction between adhesive systems and fiber posts.