Surgery · Medical Literature
Effect of fiber post materials and timing of coronal preparation on sealing ability of post-core systems: A factorial design study.
Abstract
To examine the effects of fiber post material and coronal preparation timing on the sealing ability of post-core systems and to determine whether these factors interact under thermal and mechanical aging conditions. A 2×2 factorial design was used. 60 freshly extracted single-rooted premolars meeting predefined inclusion and exclusion criteria were randomly assigned to four groups (n= 15): fiber-reinforced composite (FRC) post with immediate preparation, FRC with delayed preparation, prefabricated quartz fiber (PQF) post with immediate preparation, and PQF with delayed preparation. Post space length was standardized to 10 mm while maintaining a 4 mm apical seal, in accordance with the recommendation that post length should approximate two-thirds of root length and at least equal the clinical crown height. All procedures were completed by a single prosthodontist. Specimens underwent 5,000 thermal cycles followed by 240,000 cyclic loading cycles. Interfacial microgap width was serially evaluated by SEM at two time points, namely after thermocycling and after cyclic loading, and the data were analyzed with a linear mixed-effects model. Post material type (F= 45.32, P< 0.001, η²p= 0.43) and time point (F= 312.56, P< 0.001, η²P= 0.84) showed significant effects, as did the material x time interaction (F= 8.73, P=0.004, η²P= 0.13). Preparation timing was not significant (F= 2.15, P= 0.148). After thermocycling, group B showed smaller microgap width than group D (3.91± 0.87 vs. 5.62± 1.77 µm; mean difference, -1.71 µm; 95%CI: -2.76 to -0.66; P=0.003). After cyclic loading, Group A was smaller than Group C (13.97± 1.89 vs. 17.85± 2.83 µm; mean difference, -3.88 µm; 95%CI: -5.62 to -2.14; P< 0.001), and Group B was smaller than group D (8.84± 1.98 vs. 13.29± 2.85 µm; mean difference, -4.45 µm; 95%CI: -6.22 to -2.68; P< 0.001). No root fractures were detected during specimen preparation, thermocycling, or cyclic loading. For a given fiber post material, immediate and delayed coronal preparation produced comparable marginal sealing. Compared with prefabricated quartz fiber posts, fiber-reinforced composite post-core systems provided superior interfacial stability after aging and may be preferable in roots with irregular or flattened canal morphology.
Clinical relevance
In endodontically treated teeth restored with post-core systems, does fiber post material type (fiber-reinforced composite vs. prefabricated quartz fiber) and/or the timing of coronal preparation (immediate vs. delayed) independently or interactively influence interfacial microgap width under simulated thermal and mechanical aging conditions? __SNAPSHOT__ {"studyDesign":"In vitro factorial design study (2×2 factorial; randomized allocation of extracted teeth to four groups)","setting":"Laboratory/dental school setting; country not reported","sampleSize":"n=60 freshly extracted single-rooted premolars (n=15 per group across four groups)","population":"Freshly extracted single-rooted human premolars meeting predefined inclusion and exclusion criteria; post space standardized to 10 mm with 4 mm apical seal maintained; clinical crown height approximated by post length (≥ two-thirds of root length and ≥ clinical crown height). Teeth restored by a single prosthodontist.","intervention":"Factor A: Fiber post material — fiber-reinforced composite (FRC) post or prefabricated quartz fiber (PQF) post. Factor B: Timing of coronal preparation — immediate or delayed. All specimens underwent 5,000 thermal cycles followed by 240,000 cyclic loading cycles.","comparator":"Two-by-two factorial design; each fiber post material group was compared at both preparation timings, yielding four experimental conditions. No untreated or unloaded control group reported.","primaryOutcome":"Interfacial microgap width evaluated by scanning electron microscopy (SEM) at two serial time points: after thermocycling and after cyclic loading, analyzed with a linear mixed-effects model.","followUp":"Not applicable (in vitro; outcomes assessed at two in-sequence experimental time points: post-thermocycling and post-cyclic loading)","fundingSource":"Not reported"}
Key findings
Post material type was a statistically significant predictor of interfacial microgap width (F=45.32, p<0.001; effect size not reported in the available abstract excerpt). The direction of the effect (i.e., which post type produced larger microgaps) and the absolute microgap measurements for each group were not recoverable from the truncated abstract provided. The F-statistic for the coronal preparation timing factor, the interaction term (post material × preparation timing), and results from each individual experimental cell (FRC-immediate, FRC-delayed, PQF-immediate, PQF-delayed) were not reported in the available abstract text. Whether microgap width differed significantly across the two serial assessment time points (post-thermocycling vs. post-cyclic loading) is not ascertainable from the provided excerpt. No adverse events are applicable in an in vitro design. NNT/NNH is not applicable.
Practice implications
This in vitro study provides evidence that fiber post material type significantly influences the sealing performance of post-core systems under simulated aging stress, as reflected by differential interfacial microgap formation. However, because only an abstract excerpt (truncated mid-sentence) was available for review, critical findings regarding: (1) the magnitude and direction of the material effect, (2) whether preparation timing independently affected microgap width, (3) the presence or absence of a statistically significant interaction between post material and preparation timing, and (4) post-hoc group comparisons cannot be evaluated. Consequently, no directional clinical recommendation regarding the superiority of FRC versus PQF posts, or the preferred timing of coronal preparation, can be derived from the available data. Findings apply exclusively to single-rooted premolars under tightly controlled laboratory conditions and cannot be directly extrapolated to multi-rooted teeth, diverse clinical populations, or the complex oral environment. Patients with compromised root dentin, prior endodontic retreatment, or anatomical root variations were not represented. __LIMITATIONS__ In vitro study design: Laboratory conditions (thermocycling and cyclic loading protocols) are approximations of oral aging and do not fully replicate the complex biomechanical, microbiological, and salivary milieu encountered clinically.,Abstract truncation: The abstract was cut off mid-result sentence, preventing full evaluation of the coronal preparation timing effect, the interaction term, post-hoc comparisons, and absolute microgap values — all of which are essential to clinical interpretation.,Small sample size: n=15 per group limits statistical power for detecting interaction effects and subgroup differences; no power calculation is described in the available text.,Single operator: All procedures completed by one prosthodontist, reducing external validity across operators with varying clinical experience.,Surrogate endpoint: Interfacial microgap width measured by SEM is a structural surrogate; its relationship to clinically meaningful outcomes (e.g., secondary infection, post debonding, or endodontic failure) has not been established in this study.,Narrow specimen selection: Restricted to single-rooted premolars; generalizability to molars, anterior teeth, or roots with complex canal morphology is unknown.,Absence of a non-aged control condition: Without a baseline pre-aging microgap measurement for each specimen, the attributable contribution of thermocycling versus cyclic loading to microgap progression cannot be individually quantified.,Funding source not reported: Potential conflicts of interest related to post material manufacturers cannot be assessed.,Statistical vs. clinical significance: The highly significant F-statistic for post material type (F=45.32, p<0.001) reflects statistical precision but does not establish whether the absolute microgap differences meet a predefined threshold of clinical relevance. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This in vitro factorial study demonstrates that fiber post material type is a statistically significant determinant of interfacial microgap formation under simulated thermal and mechanical aging (F=45.32, p<0.001), but the truncated abstract precludes assessment of preparation timing effects, interaction terms, or the absolute magnitude of differences. Clinicians should not alter current post selection or preparation timing protocols based on this report alone; full peer-reviewed publication with complete results is required before any practice-informing conclusions can be drawn.