Fracture resistance after simulated crown lengthening and forced tooth eruption of endodontically-treated teeth restored with a fiber post-and-core system.
OBJECTIVE
To evaluate the effect of ferrule preparation length on the fracture resistance after simulated surgical crown lengthening and after forced tooth eruption of endodontically-treated teeth restored with a carbon fiber-reinforced post-and-core system.


METHODS
40 extracted endodontically-treated mandibular first premolars were decoronated 1.0 mm coronal to the buccal cemento-enamel junction. The teeth were divided randomly into five equal groups. The control group had no ferrule preparation (Group A). Simulated crown lengthening provided ferrule preparations of 1.0 mm (Group B) and 2.0 mm (Group C). Simulated forced tooth eruption provided ferrule preparations of 1.0 mm (Group D) and 2.0 mm (Group E). After restoration with a carbon fiber post-and-core system, each root was embedded in an acrylic resin block from 2.0 mm apical to the margins of a cast Ni-Cr alloy crown, and loaded at 150 degrees from the long axis in a universal testing machine at a crosshead speed of 1.0 mm/minute until fracture. Data were analyzed using ANOVA with Tukey HSD tests, and Fisher's exact test, with alpha = 0.05.


RESULTS
Mean failure loads (kN) for Groups A, B, C, D and E were: 1.13 (SD = 0.15), 1.27 (0.18), 1.02 (0.11), 1.63 (0.14) and 1.92 (0.19), respectively. Significant differences were shown for the effects of treatment method and ferrule length, with significant interaction between these two sources of variation (P < 0.0001). Increased apical ferrule preparation lengths resulted in significantly increased fracture resistance for simulated forced tooth eruption (P < 0.0001), but not for simulated crown lengthening (P > or = 0.24).
Meng
Qing-Fei
QF
Dental Research Institute, Nanjing Medical University, PR China.
Chen
Li-Juan
LJ
Meng
Jian
J
Chen
Ya-Ming
YM
Smales
Roger J
RJ
Yip
Kevin H K
KH
D002244:Carbon; D000077482:Carbon Fiber; D016556:Crown Lengthening / Q000009:adverse effects*; D003799:Dental Stress Analysis; D006801:Humans; D008954:Models, Biological; D003765:Models, Dental; D050793:Orthodontic Extrusion / Q000009:adverse effects*; D011176:Post and Core Technique; D014082:Tooth Fractures / Q000209:etiology*; D019231:Tooth Preparation, Prosthodontic; D019553:Tooth, Nonvital
D000077482:Carbon Fiber; D002244:Carbon