Investigating inlay designs of class II cavity with deep margin elevation using finite element method

Yung-Chung Chen,Chi-Lun Lin,Chun-Hsien Hou

doi:10.1186/s12903-021-01630-z

Yung-Chung Chen, Chi-Lun Lin + Show 1 more

Open Access

https://doi.org/10.1186/s12903-021-01630-z

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Abstract

BackgroundThis study evaluates the mechanical performance of deep margin elevation technique for carious cavities by considering the shape designs and material selections of inlay using a computational approach combined with the design of experiments method. The goal is to understand the effects of the design parameters on the deep margin elevation technique and provide design guidelines from the biomechanics perspective.MethodsSeven geometric design parameters for defining an inlay’s shape of a premolar were specified, and the influence of cavity shape and material selection on the overall stress distribution was investigated via automated modelling. Material selection included composite resin, ceramic, and lithium disilicate. Finite element analysis was performed to evaluate the mechanical behavior of the tooth and inlay under a compressive load. Next, the analysis of variance was conducted to identify the parameters with a significant effect on the stress occurred in the materials. Finally, the response surface method was used to analyze the stress responses of the restored tooth with different design parameters.ResultsThe restored tooth with a larger isthmus width demonstrated superior mechanical performance in all three types of inlay materials, while the influence of other design parameters varied with the inlay material selection. The height of the deep margin elevation layer insignificantly affected the mechanical performance of the restored tooth.ConclusionsA proper geometric design of inlay enhances the mechanical performance of the restored tooth and could require less volume of the natural dentin to be excavated. Furthermore, under the loading conditions evaluated in this study, the deep margin elevation layer did not extensively affect the strength of the tooth structure.

Highlights

This study evaluates the mechanical performance of deep margin elevation technique for carious cavities by considering the shape designs and material selections of inlay using a computational approach combined with the design of experiments method
The peak Maximum principal stress (MPS) of the deep margin elevation (DME) layer was significantly affected by a few parameters, their values in all three cases fell in the range of 1–7 MPa, which is far less than the tensile strength of the commonly used flowable resin (42 MPa) [31]; no further discussion was needed
This paper evaluated the mechanical performance of DME technique for carious cavities

Summary

Introduction

This study evaluates the mechanical performance of deep margin elevation technique for carious cavities by considering the shape designs and material selections of inlay using a computational approach combined with the design of experiments method. The most common clinical method for solving the problems related to the deep margin is the crown lengthening procedure, whereby the gingival margin of the cavity is directly exposed through periodontal surgery The drawback of this technique is the reduced crown-to-root ratio of the tooth. An unfavorable crown-to-root ratio causes the tooth vulnerable to the occlusal force and poor mechanical performance of the prosthesis, which could further lead to prosthetic failure Another proposed solution is deep margin elevation (DME). In 2012, Magne [1] again proposed using the composite resin to fill subgingival margins as an alternative to the crown lengthening procedure and termed this technique as DME This technique could maintain crown-to-root ratio, prevent unfavorable effects on tooth stability, and reduce postoperative healing time and complications; the cost was lower than that of the crown-lengthening procedure

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