Abstract
Statement of problem
The influence of different restorative materials, the divergence angle, and the preparation
design of the pulp chamber floor in endocrowns on stress distribution is unclear.
Purpose
The purpose of this finite element analysis study was to evaluate the stress distribution
and maximum von Mises stress values in endocrown restorations and remaining teeth.
Material and methods
An endodontically treated first mandibular molar was prepared with 2-mm occlusal reduction,
a butt-joint margin, and a mesial box with a 4-mm buccolingual extension to receive
an endocrown restoration. The model was then scanned, and the exported standard tessellation
language file was designed according to the anatomic references by using a computer-aided
design software program. The reference model was duplicated, and 27 variations were
formed: restorations made of IPS e.max, Vitablocs MarkII, and Vita Enamic, as well
as different divergence angles of 6, 12, and 16 degrees prepared with 3 variations
of pulp chamber floor designs, keeping the natural form, adding a 1-mm glass ionomer
pulp chamber base, and adding a 2-mm extension into the distal canal. Stress distribution
under axial loading and maximum von Mises stress values were analyzed and calculated
by using the Ansys software program.
Results
The endocrown restoration presented the lowest von Mises stress values when a 6-degree
divergence angle was used with Vitablocs MarkII. However, in other layers such as
enamel, resin cement, and pulpal floor, the lowest von Mises stress values were observed
in IPS e.max restorative material when the divergence angle was increased to 16 degrees.
No difference was found in the stress distribution pattern and maximum von Mises stress
values in the alveolar bone or periodontal ligament.
Conclusions
Endocrowns fabricated with lithium disilicate ceramics without intraradicular extension
exhibited lower stresses on tooth structure. An increase in the divergence angle improved
the stress distribution on tooth structure; however, sound dental tissue should not
be removed to achieve better stress distribution.
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Article info
Publication history
Published online: January 08, 2022
Footnotes
Supported by a grant (#46883) from the Tehran University of Medical Sciences.
This study was approved with ID (IR.TUMS.VCR.REC.1399.122) from the Tehran University of Medical Sciences.
Identification
Copyright
© 2021 by the Editorial Council for The Journal of Prosthetic Dentistry.
