Biomechanical Assessment of Restored Mandibular Molar by Endocrown in Comparison to a Glass Fiber Post-Retained Conventional Crown: 3D Finite Element Analysis
Date
2017-10-25
Authors
Abu Helal, Mohammed
Wang, Zhigang
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Abstract
Purpose: To compare equivalent and contact stresses in a mandibular molar restored
by all-ceramic crowns through twomethods: ceramic endocrowns and ceramic crowns
supported by fiber-reinforced composite (FRC) posts and core, by using 3D finite
element analysis during normal masticatory load.
Materials and Methods: Three 3D models of a mandibular first molar were made
and labeled as such: intact molar with no restoration (A); ceramic endocrown-restored
molar (B); ceramic crown supported by FRC posts and core restored molar (C).
By using 3D FE analysis with contact components, normal masticatory load was
simulated. The mvM stresses in all models were calculated. Maximal mvM stresses
in the ceramic of restorations, dentin, and luting cement were contrasted among
models and to values of materials’ strength. Contact shear and tensile stresses in the
restoration/tooth interface around restorations were also calculated.
Results: The highest mvM stress levels in the enamel and dentin for the tooth restored
by ceramic endocrown were lower in the crown ceramic than in tooth restored
with FRC posts and all-ceramic crowns; however, in the resin adhesive cement interface
it was lower for ceramic crown supported by FRC posts than the in ceramic
endocrown restoration. Themaximum contact shear and tensile stress values along the
restoration/tooth interface of ceramic endocrowns were lower than those with ceramic
crowns supported by FRC posts.
Conclusions: Ceramic endocrown restorations presented a lower mvM stress level
in dentin than the conventional ceramic crowns supported by FRC posts and core.
Ceramic endocrown restorations in molars are less susceptible to damage than those
with conventional ceramic crowns retained by FRC posts. Ceramic endocrowns properly
cemented in molars must not be fractured or loosen during normal masticatory
load. Therefore, ceramic endocrowns are advised as practicable, minimally invasive,
and esthetic restorations for root canal treated mandibular molars.
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Keywords
3D FE analysis , biomechanical behavior , endocrown , glass fiber post , mvM stress