Mechanical evaluation of cervical glass-ionomer restorations: 3D finite element study

Objectives The aim of this paper was to investigate the influence of lesion shape and depth as well as the direction of occlusal loading on the mechanical response of cervical GIC restorations. Methods A finite element model of a lower first premolar was created. Both wedged and rounded lesions were then modelled with incremental depth after which the tooth was loaded at different angles. First principal stress (tension) was employed as an indicator of material failure, by contrasting our calculated stresses with the ultimate tensile strength of the GIC and known values of bond strength between material and tooth substrate. Results Obliquely loaded teeth exhibited significantly higher tensile stress in the cervical region of the restoration. For forces inclined at angles of 30° and higher to the vertical tooth axis, the tensile stresses in the cervical margin of the restoration exceeded the ultimate material and bond strength. In contrast, lesion shape and depth have only a minor influence on tensile stress development. Conclusions Lesion depth and shape are not of primary concern from a mechanical perspective for a restorative treatment decision. By contrast, occlusal diagnosis and subsequent re-adjustments of tooth contacts do form a critical part of the treatment of non-carious cervical lesions (NCCLs).