3D-fEA of stress levels and distributions for different bases under a Class I composite restoration

To investigate the level and distribution of stresses in composite-restored mandibular first molars with various combinations of base materials.

The finite element package Abaqus was used for the stress analysis. Several different base materials were evaluated [light-cured glass ionomer (LC-GI), chemically-cured calcium hydroxide (CC-CH), and light-cured calcium hydroxide (LC-CH)] in combination with light-cured composite (LC-CP). Four models of restored molars with Class I deep cavity preparations were simulated, including (1) LC-GI/LC-CP, (2) CC-CH/LC-CP, (3) CC-CH/LC-GI/LC-CP, and (4) LC-CH/LC-GI/LC-CP. A 250N static single-point load was applied vertically on the central fossa of the tooth to simulate physical loading conditions.

In each case, the peak stresses were found to be concentrated mainly at the interfaces between the various materials and the dental tissues. In the residual tooth structures, the maximum Von Mises stresses were 20.01 MPa in model LC-GI/LC-CP, 23.85 MPa in model CC-CH/LC-CP, 23 MPa in model CC-CH/LC-GILC-CP and 21.83 MPa in model LC-CH/LC-GIILC-CP. In the LC-CP restorations, the maximum Von Mises stresses were 43.68 MPa in model LC-GILC-CP, 42.24 MPa in model CC-CH/LC-CP, 42.29 MPa in model CC-CH/LC-G/LC-CP and 42.55 MPa in model LC-CH/LC-GI/LC-CP. In the bases, the maximum Von Mises stresses were 5.71 MPa in model LC-GI/LC-CP, 0.85 MPa in model CC-CH/LC-CP, 4.69 MPa in model CC-CH/LC-GI/LC-CP, and 4.93 MPa in model LC-CH/LC-GILC-CP.