Analysis of stresses during the polymerization shrinkage of self-curing resin cement in indirect restorations: a finite-element study.
BACKGROUND
Adhesive cementation is essential for the longevity of indirect esthetic restorations. However, polymerization shrinkage of resin cement generates stress, which may cause failures in the tooth-restoration interface. So, understanding of the biomechanics of resin cement is important for predicting the clinical behavior of an esthetic indirect restoration.


OBJECTIVE
To analyze the stresses generated during polymerization shrinkage of self-curing resin cement in ceramic and in indirect resin (IR) restorations, using the finite-element method (FEM).


METHODS
Numerical study using the finite-element analysis.


METHODS
A three-dimensional (3D) model of a second molar restored with ceramic or IR onlay restoration was designed. The polymerization shrinkage of self-curing resin cement was simulated in FEM software using an analogy between the thermal stress and the resulting contraction of the resin cement. The localization and values of tensile stresses in the dental structure, cement, and adhesive layer were identified.


RESULTS
The location and value of the tensile stresses were similar for the two restorative materials. High tensile stresses were identified in the axiopulpal wall and angles of the tooth preparation, with the major stresses found in the cement located in the axiopulpal wall.


CONCLUSIONS
The high stresses values and their concentration in the angles of the prepared tooth emphasize the importance of round angles and the use of cements with lower rates of shrinkage.
Tulimar M
TM
Cornacchia
Department of Restorative Dentistry, School of Dentistry, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Guilherme C
GC
Silva
Claudia S
CS
Magalhaes
Allyson N
AN
Moreira
Estevam B
EB
Las Casas
D000537:Aluminum Oxide; D001696:Biomechanical Phenomena; D001896:Boron Compounds; D003188:Composite Resins; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis / Q000379:methods*; D020342:Finite Element Analysis; D008422:Materials Testing; D008689:Methacrylates; D008768:Methylmethacrylates; D003765:Models, Dental; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry*
D001896:Boron Compounds; D003188:Composite Resins; D008689:Methacrylates; D008768:Methylmethacrylates; D019279:Resin Cements; C477352:Sinfony composite resin; C483703:Vitadur; C100742:All-Bond 2; C049495:Super-bond; D000537:Aluminum Oxide