Morphology of root canal surface: A reflection on the process of cementation of the composite relined glass fiber post

Background: The present study was conducted to evaluate the bond strength in the different root thirds (premolars and maxillary central incisors) of composite relined glass fiber posts compared to untreated glass fiber posts cemented with dual- or chemical-cure cements. Materials and Methods: Sixty human single-rooted premolars (flat canal) ( n = 15) and 12 maxillary central incisors were used (round canal) ( n = 3). The teeth were sectioned, and the roots received endodontic treatment. The standardized preparation of the canals was carried out, and the roots were randomly divided into four groups according to the cementation systems: G1: cemented posts (dual: Ambar/Allcem); G2: relined posts (dual: Ambar/Allcem); G3: cemented posts (chemical: Fusion Duralink/Cement Post); and G4: relined posts (chemical: Fusion Duralink/Cement Post). The roots were cut to give two slices of each third of the root canal per specimen. Push-out test was conducted at a speed of 0.5 mm/min. Data were analyzed by analysis of variance and Tukey's post hoc test (α = 0.05). Results: There was no statistically significant difference between groups for the premolars (flat canal) ( P = 0.959). There was a significant difference in the central incisors between the middle and apical thirds in the cemented group when using the dual system ( P = 0.04) and between the middle and apical thirds ( P = 0.003) and cervical and apical thirds ( P = 0.033) when using the chemical system. Conclusion: Due to the anatomy of the root canal, flat canal of the premolars does not require relining, but round canal of the maxillary central incisors demands it for more secure in the bond strength.