Influence of preparation design on failure risks of ceramic inlays: a finite element analysis.
OBJECTIVE
To assess the influence of preparation design on failure risk of ceramic inlays by means of finite element (FE) analysis.


METHODS
Both 2D and 3D models of the maxillary first premolar were constructed. MOD ceramic inlays were designed with an isthmus width of 1.5 to 5.0 mm and a minimum thickness of 1 to 3 mm. Occlusal contact motion and debonding at the tooth/ceramic adhesive interface were simulated in 2D models by downward displacement of a ceramic ball (1.5 mm in diameter) onto the central groove. The stress distributions within the inlays and at the interface were analyzed using 3D models. A maximum occlusal load of 250 N was assumed.


RESULTS
The maximum principal stress at the base of the inlays was constant among models of different isthmus widths, although it decreased considerably as inlay thickness increased from 1 mm to 2 mm. The maximum shear stress at the adhesive interface increased as the width of the inlay decreased and the distance between the occlusal contact and the margin decreased to 0.3 mm or less. The maximum principal stress on the occlusal surface was relatively low and insensitive to inlay design; however, it was increased by a simulated adhesive failure.


CONCLUSIONS
The failure risk at the base of the inlay is minimized by increasing the minimum inlay thickness. As the occlusal contact becomes close to the margin, the adhesive failure risk is increased, potentially leading to an increase in risk of fracture on the occlusal surface.
Tokyo Medical and Dental University, Tokyo, Japan.
Masahiro
M
Ona
Chie
C
Watanabe
Yoshimasa
Y
Igarashi
Noriyuki
N
Wakabayashi
D003198:Computer Simulation; D001840:Dental Bonding; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000379:methods*; D020342:Finite Element Analysis; D007284:Inlays
D003776:Dental Porcelain