Predictions of cement microfracture under crowns using 3D-FEA

Abstract

Purpose: The objective of this research study was to test the effects of (1) crown margin type, (2) cement type, (3) cement thickness, (4) loading direction, and (5) loading magnitude on stress levels and distributions within luting cement that might lead to cement microfracture using three-dimensional Finite Element Analysis techniques.Materials and Methods: Thirty-two three-dimensional computer models, as well as models for standards, were generated for a mandibular first premolar. Crown preparations exhibited shoulder or chamfer margin configurations, and zinc phosphate, zinc polycarboxylate, glass ionomer, and resin cements were used in thicknesses of 25 or 100 m. Modeled crowns were loaded axially or obliquely at 10 and 100 MPa. Areas and levels of stress concentrations within the cement were determined.Results: Stresses in the cement were low for all situations except 100 MPa oblique stressing. Stresses at the margins of crowns with chamfer marginal configuration were higher than those with shoulder margins. Stresses under oblique stressing were 10 to 150 times higher than under axial stressing. Except for Zn phosphate cement, cement thickness minimally affected stress levels and distributions. Greater stresses were found in cements with the greater Young's modulus.Conclusions: Although the chamfer margin design could lead to greater stresses near the margins that places the cement at risk for microfracture and possible crown failure, glass-ionomer and composite resin cements have more favorable mechanical properties for resisting microfracture.

Effects of geometry on fracture initiation and propagation in all‐ceramic crowns

“…Unfortunately, they generally do not incorporate variations in axial wall height around the periphery of the margin. Instead, they are lim-ited to a single geometry with fixed axial wall height and focus on other crown design factors, including taper of the axial wall, [8][9][10] crown and/or core thickness, 11 margin configuration (e.g., chamfer vs. shoulder), 9,12,13 uniformity and thickness of cement space, 12,14 and other issues of clinical relevance. Thus, they provide little insight into the role the variations in axial wall height might play in stress distribution and fracture evolution.…”

Finite Element Stress Analysis of Diastema Closure with Ceramic Laminate Veneers

“…Studies by Magne et al 14 on the natural central incisor also came to the same conclusion. Although numerous studies have been made on the modifications of tooth preparation, [15][16][17][18][19][20] effects of margin designs and load angles, [21][22][23] ceramic materials, [24][25][26][27][28] and cement polymerizations, [29][30][31][32][33][34] fewer studies have examined the unsupported PLV material in diastema closure specifically. The purpose of this study was to use finite element stress analysis to examine the relative importance of variables such as PLV extensions, loading angle, and loading level, for the case of feldspathic ceramic veneering of teeth to manage diastema.…”

Influence of post‐core material and cement peculiarities on stress of post‐cores under ultrasonic vibration: a three‐dimensional finite element analysis

“…Furthermore, failure of the cement is often not caused by the stress at a certain moment, but by fatigue (Kamposiora et al . 2000). Stresses far below the ultimate strength of the materials can cause failure due to fatigue (Kamposiora et al .…”

“…In the present study, stresses in the cements and roots also increased with an increase in the elastic modulus of the cements, which was consistent with other studies on FEA (Kamposiora et al . 2000, Proos et al . 2003a,b).…”