Comparison of Bulk Polymeric Resin Composite and Hybrid Glass Ionomer Cement in Adhesive Class I Dental Restorations: A 3D Finite Element Analysis

Abstract

This study aimed to investigate the mechanical behavior of resin composites and hybrid glass ionomer cement in class I adhesive dental restorations under loading and shrinkage conditions. Three CAD models of a mandibular first molar with class I cavities were created and restored with different techniques: a bi-layer of Equia Forte HT with Filtek One Bulk Fill Restorative composite (model A), a single layer of adhesive and Filtek One Bulk Fill Restorative (model B), and a single layer of Equia forte HT (model C). Each model was exported to computer-aided engineering software, and 3D finite element models were created. Models A and B exhibited a similar pattern of stress distribution along the enamel-restoration interface, with stress peaks of 12.5 MPa and 14 MPa observed in the enamel tissue. The sound tooth, B, and C models showed a similar trend along the interface between dentine and restoration. A stress peak of about 0.5 MPa was detected in the enamel of both the sound tooth and B models. Model C showed a reduced stress peak of about 1.2 MPa. A significant stress reduction in 4 mm deep class I cavities in lower molars was observed in models where non-shrinking dental filling materials, like the hybrid glass ionomer cement used in model C, were applied. Stress reduction was also achieved in model A, which employed a bi-layer technique with a shrinking polymeric filling material (bulk resin composite). Model C's performance closely resembled that of a sound tooth.

Keywords: dental materials; dental restoration; finite element analysis; material properties; resin composite.

Figure 1

Three-dimensional CAD model of a restored tooth, incorporating three variations of class II mesio-occlusal cavities.

Figure 2

Solid food was modeled on the occlusal surface to simulate the contact between the tooth surface and the food bolus.

Figure 3

Stress distributions for the first principal stress in enamel, dentin, and restorative material are shown for each model, considering both occlusal and transversal loads as well as the shrinkage effect. The analysis includes two cross-sections taken along the bucco-lingual axis of the tooth.

Figure 4

Global contour plots of the first principal stress for each design.

Figure 5

The first principal stresses were charted along the assessment track and compared among the various models. Each model displayed a high stress magnitude at the interfaces between tooth tissues and the restorative material.