Evaluation of stresses created by forces from different directions on paediatric crowns using finite element analysis

BACKGROUND: Finite element analysis (FEA) is a widely used computational method for assessing stress distribution in dental structures. Understanding the mechanical behaviour of paediatric crowns under functional loads is essential for optimising restorative material selection. AIM: This study aims to evaluate the stress distribution in maxillary primary second molars restored with stainless steel, zirconia, and strip crowns under occlusal and lateral forces using FEA. DESIGN: Three-dimensional models of primary second molars with full coronal restorations were analysed. Vertical, horizontal and oblique force vectors were applied, and minimum and maximum principal stresses were calculated using finite element analysis software (Algor Fempro). RESULTS: Under vertical (axial) loading, the maximum principal stress values recorded on the root surface were 10.4 MPa (control), 7.8 MPa (stainless steel crown), 17 MPa (zirconia crown) and 10.3 MPa (strip crown). Stresses increased markedly under oblique and, in particular, horizontal forces in every model; the strip crown produced the highest root stresses (up to 505.7 MPa under horizontal loading), whereas the zirconia crown produced the highest stresses within the crown itself. CONCLUSION: All of the crown materials examined produced relatively low stresses under vertical (axial) loading, but their mechanical performance varied considerably with the direction of loading, with the highest stresses occurring under horizontal forces. Zirconia crowns concentrated the highest stresses within the crown, stainless steel crowns produced the most uniform stress distribution and the lowest root stresses, and strip crowns developed markedly elevated root stresses under non-axial loading. On the basis of stress distribution, the stainless steel and zirconia crowns performed more favourably than the strip crown under non-axial loading. These findings can inform material selection for full coronal restorations in paediatric dentistry.