Two dimensional finite element analysis of ceramic veneer bonding layer / 实用口腔医学杂志

ABSTRACT

Objective: To intimately assess the internal stress distribution in ceramic veneer bonding layer. Methods:Six buccolingual cross section models of the incisor restored with IPS-Empress ceramic veneer were built with the MSC/NASTRAN software. 2D-finite element method was used to analyze the stress distribution regularity of the bonding layer on the models under different functional load. Results: Stress concentration areas of ceramic veneer bonding layer were regularly located on the incisal margin and cervical margin. Under the same condition, incisal load caused highest stresse on the adhesive layer. Following the load shift from incisal to gingival area, the stress was gradually decreased.When the functional load acted on the palate margin of the restoration, the compressive stress on the bonding layer was significantly increased. Different load angle generated stress change in the bonding layer. The shear stress on adhesive layer increased following the horizontal load angle increasing close to the debonding level. Among the different incisal reduction designs there was no significant Von Mises stress variation under the same load condition. However, when the incisal edge was reduced by more than 4 mm, the tensile stresses in the bonding layer greatly increased. Conclusion: Restoration margin should be kept away from the tooth contact area, be exposed to minimal occlusion contact. The functional load should be induced to follow the tooth long axis. Edge to edge occlusion should be avoided. When incisal areas need to be altered, the incisal overlap or butt margin design will not cause any stress problem in the bonding layer. When restoring the incisal defect for more than 4 mm, the bonding agents must be selected carefully.