Influence of connector size and ceramic type on stress distribution in fixed partial denture with endocrown and inlay...

The present study aimed to evaluate endocrown and inlay as retainers of fixed partial denture (FPD) and to compare the effect of restoration design, ceramic type, and connector size on stress distribution using finite element analysis.

Cone-beam computed tomography of the patient was selected and entered into Catia v5-21 software for modeling. Then, FPD was designed to replace the second premolar. Three restoration materials including lithium disilicate (LDS), zirconia reinforced lithium silicate (ZLS) and Zirconia (Zr) and three connector size including 4×4, 3×4, 3×3 mm, and in terms of preparation design as both retainer endocrown (EE), both inlay (II), first premolar inlay and first molar endocrown (IE), and first premolar endocrown and molar inlay (EI). Finally, the mechanical information was entered into the Ansys software (ANSYS Inc.). Then the mesh sub-regions were defined. Finally, a force of 300 Newton was applied vertically and at an oblique. Then, the maximum stress level and its location were compared and examined among the different study groups, and finally, the data were assessed.

The minimum stress level was observed in the EI-LDS with 3 × 4 connector size under vertical loading (55.1 MPa), and the highest stress level was observed in the IE-Zr with 3 × 4 connector dimension under oblique loading (558.8 Mpa). The lowest strain (0.5) was observed in the EI-Zr with 4 mm × 4 mm connector size under vertical loading. Conversely, the highest strain (4.1) was seen in the EE-LDS with a 4 mm × 3 mm connector under oblique loading.

Partial ceramic restorations may serve as effective conservative alternatives to conventional full crowns as retainers for posterior FPDs.