Erbium-Laser Combined Treatment of Fiber Post and Root Canal

Objectives: Bonding failure remains an issue in the use of fiber posts for crown restorations. This experiment examines the effect on bonding of combined treatment on both root canal and fiber post by Er:YAG laser.
Methods: Sixty mandibular first premolars were prepared and divided into 6 groups (n = 10 per group): G1: root canal with 2.5% NaClO treatment, no treatment of fiber post; G2: root canal with 2.5% NaClO treatment and fiber post with airborne-particle abrasion; G3: root canal with Er:YAG laser treatment and fiber post with airborne-particle abrasion; G4: root canal with Er:YAG laser treatment, no treatment of fiber post; G5: root canal with 2.5% NaClO treatment, fiber post with Er:YAG laser irradiation; G6: Er:YAG laser combined irradiation of both root canal and fiber post.Bond strength in each group was analyzed by micro push-out test. Data were analyzed by TUKEY test and two-way ANOVA (α= 0.05). Failure modes were observed and counted by stereomicroscope and root canal and fiber post surface analysis was performed by SEM.
Results: Bonding strengths in the treated groups were significantly improved compared with the untreated groups. SEM analysis showed that the smear layers of groups with root canals treated by Er:YAG laser irradiation were significantly reduced compared with the control. In groups with fiber posts treated with Er:YAG laser irradiation, the surfaces of the fiber posts showed higher roughness and the epoxy matrix was partially removed.
Conclusions: Er:YAG laser combined treatment of fiber post and root canal wall produced synergistic effects compared to fiber post or root canal wall alone,and increasing bond strength over that expected by the sum of individual treatments.