A comparison of the fracture resistances of endodontically treated mandibular premolars restored with endocrowns and glass fiber post-core retained conventional crowns

Abstract

PURPOSEThis in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns.MATERIALS AND METHODSThirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to 45° oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (α=.05).RESULTSThe fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI.CONCLUSIONFor the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.

Fracture Resistance of Endodontically Treated Teeth Restored with Lithium Disilicate Crowns Retained with Fiber Posts Compared to Lithium Disilicate and Cerasmart Endocrowns: In Vitro Study

“…Furthermore, the adaptation of the inner surface of a restoration and the replication of the occlusal morphology are better [33].…”

“…Despite these advantages, there are clinical problems with the depth of the optical impression to record the crown, pulp chamber, and sometimes part of the canal [33].…”

Fracture strengths of endocrown restorations fabricated with different preparation depths and CAD/CAM materials

“…2) 14) . In this study, 45 degrees angle was selected to mimic intraoral conditions so that the force was conducted in both the axial and the lateral directions 34) . Then, all fractured surfaces were analyzed using a stereomicroscope (Olympus SZ4045 TRPT, Osaka, Japan) at ×20 magnification to identify the failure modes.…”

Fracture resistance of all‐ceramic crowns based on different preparation designs for restoring endodontically treated molars

“… However, Biacchi and colleagues suggested endocrowns are best limited for molar restoration as bicuspids may present with unfavorable mastication force vectors, with Bindl et al further noting that bicuspids have less available bonding surface, greater height to width ratio, and smaller pulp chamber dimensions which all serve to intensify lever force vectors. These reports were recently reinforced by Guo and colleagues who reported that endocrowns displayed no advantage compared to conventional methods of restoring endodontically treated mandibular bicuspids. Clinically, initial reports reported approximately a 95% molar endocrown survival over 26 months, and recent results of a 7 and 10 year clinical studies are the first long‐term reports that further suggest the viability of the endocrown method …”

“…For the restoration of endodontically treated teeth, CAD/CAM advocates emphasize the “endocrown” method, which consists of a merged crown and core unit adhesively bonded into the pulp chamber and the remaining tooth structure . The endocrown method is said to provide a more conservative option to traditional post and core restorative strategies while providing equitable results . Dejak and Młotkowski using an in silico finite element analysis reported that under simulated masticatory function the endocrown had lower dentin stress concentration than compared to traditional post and core methods.…”