In vitro comparison of the fracture resistance and failure mode of fiber, ceramic, and conventional post systems at various stages of restoration

Abstract

Purpose: This in vitro study evaluated 6 post systems over 4 simulated clinical stages of tooth restoration to (1) determine quantitatively the fracture resistance strength at each stage when a static loading force is applied to cause failure; (2) determine the failure mode for each post system at each simulated clinical stage; and (3) determine the feasibility of removing failed post systems.Materials and Methods: Ten post systems made with various materials and designs were tested at the following 4 stages of simulated clinical treatment: stage #1: posts only, loaded using a 3-point loading model to failure, to determine transverse strengths and failure modes for each post system; stage #2: posts alone, bonded into teeth; stage #3: posts bonded into teeth with core build up; stage #4: post and core build up and full veneer restoration. For stages #2 through #4, the coronal portion of 60 mandibular premolars was amputated at the cemento-enamel junction, the canals were treated endodontically, and the specimens were mounted in acrylic blocks. A testing force was applied to the posts at 90°to the long axis of the tooth, 4 mm from the cemento-enamel junction. The O'Brien test for constant variance was performed over the treatment groups. For nonconstant variance, the Welsh analysis of variance was used to test for equalities of treatment means. The Tukey Kramer procedure determined which treatment procedures differed.Results: The failure thresholds for each post system were significantly different at each stage of testing, but the order of test results by post type remained generally consistent from one stage to the next. ParaPosts (Coltene, Whaledent Int, New York, NY) and core build up resulted in significantly higher failure thresholds through all 4 stages of testing. This post system also consistently displayed a high number of nonfavorable tooth fractures. FibreKor post and cores (Jeneric Pentron Inc, Wallingford, CT) resulted in significantly lower failure threshold values in stages #2 through #4. This post system displayed no tooth fractures in stages #2 and #3 and a similar number of nonfavorable tooth fractures in stage #4 when compared with the other systems. C-Post (Bisco Dental Products, Schaumburg, IL), CosmoPost (Ivoclar Vivadent North America Inc, Amherst, NY), and AesthetiPost (Bisco Dental Products) grouped in descending order through stages #2 to #4. These systems displayed intermediate fracture resistance strengths, as well as a moderate number of nonfavorable tooth fractures. CosmoPost exhibited a significant number of brittle post fractures with fragments left in the root canal at all stages. The fracture resistance of the cast metal post varied from stage to stage. No teeth fractured at stage #2. At stage #3, 9 of 10 teeth fractured nonfavorably, and all teeth fractured nonfavorably in stage #4.Conclusions: The fiber posts evaluated provided an advantage over a conventional post that showed a higher number of irretrievable post and unrestorable root fractures. At the stage of final restoration...

Fracture resistance of the buccal cuSPS of root filled maxillary premolar teeth restored with various techniques

“…Several authors reported that high fracture resistance was obtained when the elastic moduli of the post and dentine were compatible with each other (Ferrari et al. 2000, Cormier et al. 2001, Akkayan & Gulmez 2002, Maccari et al.…”

Effects of luting agent and thermocycling on bond strengths to root canal dentine

“…Various studies have demonstrated the favourable physical properties of fibre‐reinforced composite (FRC) posts (Asmussen et al. 1999, Cormier et al. 2001, Mannocci et al.…”

Restoring teeth following root canal re‐treatment

“…The use of fiber posts reduces the risk of root fracture significantly as the modulus of elasticity of these posts is close to that of dentin (147). Research has demonstrated that a significant proportion of metal post failures are due to terminal root fractures (149,150). Research has demonstrated that a significant proportion of metal post failures are due to terminal root fractures (149,150).…”