title: Influence of fiber posts on the fracture resistance of endodontically treated premolars with different dental defects.
abstract: This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading. Fifty extracted single-rooted mandibular premolars were randomized into five groups. Each group was prepared according to numbers of residual walls ranged from 0 to 4. Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts. In no-post groups, gutta percha point 2 mm below cemento-enamel junction was removed. Composite resin was adapted to the well and used to shape the core directly. Each tooth was restored with a complete metal crown. Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles. Then a quasi-statically load was applied in a universal testing machine 30° to the long axis with a crosshead speed of 1 mm⋅min(-1) until fracture. Data were analyzed with one-way analysis of variance and pairwise comparison (P<0.05). No specimens failed during dynamic loading. The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant (P<0.05). Placement of fiber posts had a significant effect when fewer than two walls remained (P<0.05), but it had no significant influence in groups with two, three or four walls (P>0.05). Fiber post did not change failure mode, and the fracture pattern was mainly favorable. More dentin walls need to be retained in clinic. When no less than two walls remained, a fiber post is not always necessary.
authors.affiliation: School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Qian-Qian
authors.initials: QQ
authors.lastname: Hou
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Gao
authors.forename: Lei
authors.initials: L
authors.lastname: Sun
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D003188:Composite Resins; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003804:Dentin / Q000502:physiology; D006801:Humans; D011176:Post and Core Technique; D011791:Quartz; D014082:Tooth Fractures / Q000517:prevention & control*; D019553:Tooth, Nonvital
chemical_list: D003188:Composite Resins; D011791:Quartz
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