Finite element and in vitro study on biomechanical behavior of endodontically treated premolars restored with direct or indirect composite restorations

Abstract

Objectives of the study were to investigate biomechanical properties of severely compromised premolars restored with composite restorations using finite element analysis (FEA), and in vitro fracture resistance test. A 3-D model of an endodontically treated premolar was created in Solidworks. Different composite restorations were modelled (direct restoration-DR; endo-crown-EC; post, core, and crown-C) with two different supporting tissues: periodontal ligament/alveolar bone (B), and polymethyl methacrylate (PMMA). Models were two-point axially loaded occlusally (850 N). Von Mises stresses and strains were calculated. The same groups were further tested for static fracture resistance in vitro (n = 5, 6.0 mm-diameter ball indenter, vertical load). Fracture resistance data were statistically analyzed (p < 0.050). The highest stresses and strains in all FEA models were observed on occlusal and vestibular cervical surfaces, corresponding to fracture propagation demonstrated in vitro. C showed the lowest stress in dentin, while EC showed lower stresses and strains in crown cement. B models demonstrated larger high stress areas in the root than PMMA models. No significant differences in fracture resistance (N) were observed between groups (DR: 747.7 ± 164.0, EC: 867.3 ± 108.1, C: 866.9 ± 126.3; p = 0.307). More conservative restorations seem a feasible alternative for endodontically treated premolars to conventional post-core-crown.

Biomechanical performance of endocrown and core‐crown restorations: A systematic review

“…[11][12][13]20 Eight studies evaluated the load to failure. Similar results for ED and PCC were observed in six studies, [11][12][13][14]16,22 such similarity is associated with the material adopted in two of these analyses. 12,13 One report showed dependence on the remaining coronal structure, as ED with circumferential ferule was similar to PCC, but ED groups with only buccal ferule or in the absence of ferule were inferior to PCC.…”

“…However, a relevant number of specimens showed fractures involving the remaining tooth structure and the tooth/restoration adhesive interface. 3,8,[10][11][12][13]16,17,20,22,24 Therefore, when an adequate thickness of restorative material is adopted, the load to failure will also be dependent on the strength of adjacent structures. Some studies showed superior load to failure when ferule was present in either ED at anterior and premolar teeth 2,11 or for CC in anterior teeth; 3 Note: Superscript letters represent the statistical differences among groups for each study.…”

“…8,36 Four studies did not find relevant differences in failure patterns for ED and PCC. 12,13,20,22 Two studies observed most favorable failure patterns for PCC, 8,16 while other two analyses observed most favorable failure patterns for ED. 11,14 Eight studies evaluated the stress distribution in dentin with four of them showing lower stress concentration in supporting tooth structures restored with ED in comparison to PCC 27,29,35,36 and other 4 showing lower stresses with PCC.…”

Prior Restorative Procedures to Endodontic Treatment

“…The decision to restore the tooth using only a direct composite restoration is justified by the fact that it is a simplified and feasible procedure to recover the biomechanical properties of endodontically treated premolars with the structural loss [ 20 ], based on the principles of minimally invasive dentistry [ 21 ]. The use of a fiber post could have been a clinical alternative, however, it was clinically demonstrated that post-placement has no influence on reducing the failure of post-endodontic restorations and might not be necessary in teeth with some structure preserved [ 22 ].…”

Structurally compromised teeth. Part I: Clinical considerations and novel classification proposal

“…In presence of a foundation restoration, the forces created during oral functions are likely to be concentrated in the regions coronal and apical to the bone crest in a manner that may favor the dislodgement of the bonded restoration and expose the residual tooth structure to fracture 21,22 . This risk seems further increased in case of surgical crown lengthening owing to the unfavorable crown/root ratio 23 .…”