Abstract
PurposeThis study aimed to evaluate the influence of different types of restorative materials and resin cements on the stress distribution in the regions of the restoration, cement layer and dental remnant in endodontically treated posterior endocrowns.MethodsA 3D finite element analysis (FEA) model of the first mandibular molar that was restored with an endocrown designed by computer-aided design (CAD) software was generated. Three kinds of restorative materials (Vita Enamic (VE), IPS e.max CAD (EMX) and Grandio blocs (GR)) and two types of cementing materials (NX3 and Maxcem Elite Chroma (MX)) were analysed with such a model. The food layer was also designed before vertical (600 N) forces were applied to simulate physiological masticatory conditions. Thermal expansion was used to simulate the polymerization shrinkage effects of cement layers. The results were obtained by colorimetric graphs of the maximum principal stress in the restoration and tooth remnant. The failure risk of the cement layer was also calculated based on the normal stress.ResultsThe elastic modulus was positively correlated with the tensile stress peak values in the restoration, mainly at the intaglio surface. However, in the cervical enamel and cement layer, restorative material with a higher elastic modulus generated lower peak stress values. The cement with a higher elastic modulus resulted in higher stress peak values inside the cement layer. The combination of EMX (restorative material) and NX3 (cement material) in the cement layer resulted in the lowest failure risk.SignificanceThe ceramic material EMX with a higher elastic modulus appeared to be more effective at protecting the cement layer and residual enamel tissue. Based on the analysis of the failure risk of the cement layer, the combination of EMX and NX3 was recommended as an optional material for endocrowns for endodontically treated posterior teeth.
Highlights
In recent years, the development of adhesive dentistry, in conjunction with improvements in the mechanical properties of restorative materials and their manufacturing process, has enabled restorations to recover all or part of weakened tooth resistance, increasing the possibility of more conservative restorative procedures [1,2,3].He et al BMC Oral Health (2021) 21:495Less invasive preparations and greater preservation of tooth structure have been the new principles in teeth restoration [4]
The endocrown is a new minimally invasive restoration method for endodontically treated teeth (ETT), which is composed of a butt plane and retainer deeply fixed into the internal walls of the pulp chamber [5, 6], and the retentive effect benefits from the macroscopic and microscopic mechanical retentions provided by the pulp cavity and adhesion [7]
This study aimed to evaluate the stressed regions in the posterior endocrown and in the cement layer according to different restorative materials and different resin cements
Summary
The development of adhesive dentistry, in conjunction with improvements in the mechanical properties of restorative materials and their manufacturing process, has enabled restorations to recover all or part of weakened tooth resistance, increasing the possibility of more conservative restorative procedures [1,2,3].He et al BMC Oral Health (2021) 21:495Less invasive preparations and greater preservation of tooth structure have been the new principles in teeth restoration [4]. The development of adhesive dentistry, in conjunction with improvements in the mechanical properties of restorative materials and their manufacturing process, has enabled restorations to recover all or part of weakened tooth resistance, increasing the possibility of more conservative restorative procedures [1,2,3]. He et al BMC Oral Health (2021) 21:495. A restorative material that optimizes the stress distribution in the adhesive interface during occlusal loading could alleviate the reported clinical problems and promote a higher endocrown success rate
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