Load Capability of Excessively Flared Teeth Restored with Fiber-reinforced Composite Posts and All-ceramic Crowns

Abstract

SUMMARYThis investigation evaluated the stabilizing effect of glass fiber reinforced posts (FRP) luted with self-adhesive universal cement on the fracture resistance of excessively flared endodontically treated teeth (ETT). Values were compared to teeth with no ferrule, 2 mm ferrule and resin cement for luting with 2 mm ferrule.Thirty-two caries-free maxillary central incisors were randomly assigned to 4 groups (n=8) and endodontically treated. Two groups were flattened 2 mm above and 2 groups at the cemento-enamel junction (CEJ). The teeth received FRPs as follows: 1) post was cemented with selfadhesive cement (RelyX Unicem, 3M ESPE) (U), no ferrule (F) was prepared, root canal entrance was excessively flared with a remaining wall thickness of 0.5 -0.75 mm (UNF/flared); 2) post was cemented with U, no F was prepared; 3) post was luted with U, F was prepared; 4) post was cemented with a resin cement (Panavia F, Kuraray, Japan), F was prepared. All specimens were built-up using a resin composite (Clearfil Core, Kuraray). All-ceramic crowns were adhesively luted (U). Specimens were exposed to thermo-mechanical loading and statically loaded until failure. INTRODUCTIONThe restoration of a tooth with excessively flared root canal entrances is clinically problematic with an endodontically-treated tooth (ETT). Flaring might be attributed to immature development of the root, serious structural damage by carious lesions, previous restoration with large post diameters or over-instrumentation The fracture resistance of excessively flared endodontically-treated teeth (ETT) without ferrule preparation is not acceptable. Adhesively luted FRC posts with 2 mm ferrule are recommended.

Loading Standardization of Postendodontic Restorations In Vitro: Impact of Restorative Stage, Static Loading, and Dynamic Loading

“…32 The maximum load capability at the stage of final crown restoration is in a range comparable to that found in previous studies. 33,34 The fracture patterns in the crown-restored groups 3 and 4 correspond to patterns found earlier. 24 There was no post fracture observed, although an unusual number of crown losses in group 4 was apparent.…”

“…35 We believe that the maximum load capability is less affected by the strength of the post than by the (tensile) strength of the surrounding hard tissue that is directly correlated to its amount. 34 The most important requirement to achieve the maximum load capability of ETT is a remaining minimum of 2-mm cervical tooth structure, the so-called ferrule effect. To provide the ferrule effect, crown cementation is advisable.…”

Fracture resistance of premolars with one remaining cavity wall restored using different techniques

“…Choosing the best technique and material according to functional demands and determining the amount of remaining tooth structure for optimum strength against fracture are key factors for success. Against this background, different materials and restorative techniques have been proposed in recent years to improve the therapeutic success of teeth with major structural loss [14][15][16][17] . Studies have evaluated the fracture resistance of post-retained direct restorations.…”

Crack Propagation in Post-Core Rehabiltation of a Maxillary Central Incisor After Root Reconstruction

“…The damage not necessarily implies in fracture of the root, but small cracks may have been formed inside the root wall. Crack propagation is associated to longterm fatigue root fracture upon functional cyclic loading [22,43,44]. Based on the fatigue crack growth mechanism, a pre-existing flaw of sufficient size (approximately 0.3-1.0 mm) can grow to catastrophic proportion with cyclic loading at stresses below 30 MPa [45].…”