[A preliminary analysis of the ratio between the upper and lower anterior teeth].

Purpose: To evaluate the effect of two post-coating methods with dental adhesives on the bonding properties between fiber posts and core resin.
Methods: Thirty-six fiber posts were randomly divided into 3 groups and treated as following: Group A, no treatment as control; Group B, coated with dual-cured XP bond and light curing; Group C, coated with XP bond and self-curing. All treated posts were cemented to Definit Core resin and made to stick-shape bonding specimens. All the specimens were subjected to microtensile bonding strength (μTBS) tests and scanning electronic microscopy (SEM) observation after storage in water for 24 h and 1 month, respectively. The results of μTBS tests were analyzed by SPSS13.0 software package.
Results: After 24 h water storage, μTBS of Group C (17.03 MPa ± 6.01 MPa) was significantly higher than that of Group A (9.64 MPa ± 4.59 MPa) and Group B (11.99 MPa ± 6.07 MPa). After 1 month water storage. there was no significant difference among the three groups. The μTBS of Group B (8.17 MPa ± 4.25 MPa) and C (9.85 MPa ± 4.11 MPa) both decreased after 1 month water storage. Interfacial gaps were also detected in groups B and C after 1 month water storage under SEM.
Conclusions: Effect of post-coating with adhesives on the immediate bonding strength between fiber posts and core resin depends on the curing mode of adhesives. Both two post-coating methods would decrease the bonding durability of fiber posts and core resin.