Influence of Occlusal Cusp Inclination and Restoration Thickness on the Biomechanical Performance of Lithium Disilicate Molar Endocrowns: A 3D Finite Element Analysis

Layla Hassouneh; Nawar Naguib Nawar; Mohammad Atieh; Dilek Yigit; Venkateshbabu Nagendrababu; Ove A. Peters; Manal Matoug-Elwerfelli

doi:10.1055/s-0045-1810442

European Journal of Dentistry, Table of Contents

CC BY 4.0 · Eur J Dent
DOI: 10.1055/s-0045-1810442

Original Article

Influence of Occlusal Cusp Inclination and Restoration Thickness on the Biomechanical Performance of Lithium Disilicate Molar Endocrowns: A 3D Finite Element Analysis

Layla Hassouneh

¹Department of Conservative Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan

,

Nawar Naguib Nawar

²Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt

,

Mohammad Atieh

¹Department of Conservative Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan

,

Dilek Yigit

³Department of Pre-Clinical Oral Sciences, College of Dental Medicine, QU Health, Qatar University, Doha, Qatar

,

Venkateshbabu Nagendrababu

⁴Department of Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates

,

Ove A. Peters

⁵School of Dentistry, University of Queensland, Brisbane, Australia

,

Manal Matoug-Elwerfelli

³Department of Pre-Clinical Oral Sciences, College of Dental Medicine, QU Health, Qatar University, Doha, Qatar

› Author Affiliations

Abstract

Objectives

This study used finite element analysis to investigate the effect of occlusal cusp inclination and restoration thickness of endocrowns on the stress distribution and biomechanical performance.

Materials and Methods

A total of six models of a mandibular first molar representing two different heights of remaining tooth structure above the cemento-enamel junction (1.5 and 3 mm), each with three different buccal cusps inclination angles (original, 10 degrees, and 20 degrees increase in cusp inclination angles) were generated. Models were designated as: 1.5/original, 1.5/10 degrees, 1.5/20 degrees, 3/original, 3/10 degrees, and 3/20 degrees. All models were subjected to an oblique load of 400 N. The maximum principal stress (MPS), maximum shear stress (MSS) at the cement interface, and factor of safety (FoS) were calculated.

Results

Increasing the cuspal inclination by 10 degrees in models with a 1.5-mm remaining tooth structure, resulted in a 20% reduction of the MPS in the dentine (27.2 MPa), in comparison with original cuspal inclines (33.9 MPa). However, increasing the cusp inclination in model 1.5/20 degrees resulted in a comparable dentinal stress reduction (17%, 28 MPa) accompanied with an increase in the MSS at the cement interfaces (26.8 MPa), in comparison with 1.5/original (18 MPa). On the other hand, increasing the cusp inclination angle in models 3/10 degrees and 3/20 degrees led to a reduction in MPS within the dentine by 1 and 2%, respectively, while causing an increase in the MSS at the cement interfaces (16.4 and 16.0 MPa, respectively), in comparison with 3/original (11 MPa). Models 1.5/original and 3/original reported the minimum FoS values (3.10 and 3.38, respectively), while model 1.5/10 degrees reported the highest FoS value (3.86).

Conclusion

Within the limitations of the current study, cusp inclination adjustments up to 10 degrees may enhance stress distribution in endocrown-restored molars with limited coronal structure.

Keywords

endocrowns - finite element analysis - lithium disilicate - occlusal design - root canal treated teeth - stress distribution

Full Text

References

References
1 Tang W, Wu Y, Smales RJ. Identifying and reducing risks for potential fractures in endodontically treated teeth. J Endod 2010; 36 (04) 609-617
2 Dartora NR, de Conto Ferreira MB, Moris ICM. et al. Effect of intracoronal depth of teeth restored with endocrowns on fracture resistance: In-vitro and 3-dimensional finite element analysis. J Endod 2018; 44 (07) 1179-1185
3 Sedrez-Porto JA, Rosa WL, da Silva AF, Münchow EA, Pereira-Cenci T. Endocrown restorations: a systematic review and meta-analysis. J Dent 2016; 52: 8-14
4 Bindl A, Mörmann WH. Clinical evaluation of adhesively placed Cerec endo-crowns after 2 years--preliminary results. J Adhes Dent 1999; 1 (03) 255-265
5 Hassouneh L, Jum'ah A, Ferrari M, Wood DJ. A micro-computed tomography analysis of marginal and internal fit of endocrowns fabricated from three CAD/CAM materials. Oper Dent 2023; 48 (01) 79-89
6 Rodrigues RF, Ramos CM, Francisconi PAS, Borges AFS. The shear bond strength of self-adhesive resin cements to dentin and enamel: an in vitro study. J Prosthet Dent 2015; 113 (03) 220-227
7 Hassouneh L, Jum'ah AA, Ferrari M, Wood DJ. Post-fatigue fracture resistance of premolar teeth restored with endocrowns: an in vitro investigation. J Dent 2020; 100: 103426
8 Tribst JPM, Dal Piva AMO, de Jager N, Bottino MA, de Kok P, Kleverlaan CJ. Full-crown versus endocrown approach: a 3D-analysis of both restorations and the effect of ferrule and restoration material. J Prosthodont 2021; 30 (04) 335-344
9 Govare N, Contrepois M. Endocrowns: a systematic review. J Prosthet Dent 2020; 123 (03) 411-418.e9
10 Rigolin FJ, Miranda ME, Flório FM, Basting RT. Evaluation of bond strength between leucite-based and lithium disilicate-based ceramics to dentin after cementation with conventional and self-adhesive resin agents. Acta Odontol Latinoam 2014; 27 (01) 16-24
11 Sasse M, Krummel A, Klosa K, Kern M. Influence of restoration thickness and dental bonding surface on the fracture resistance of full-coverage occlusal veneers made from lithium disilicate ceramic. Dent Mater 2015; 31 (08) 907-915
12 Dal Piva AMO, Tribst JPM, Borges ALS, Souza ROAE, Bottino MA. CAD-FEA modeling and analysis of different full crown monolithic restorations. Dent Mater 2018; 34 (09) 1342-1350
13 Khers SC, Carpenter CW, Vetter JD, Staley RN. Anatomy of cusps of posterior teeth and their fracture potential. J Prosthet Dent 1990; 64 (02) 139-147
14 Rosentritt M, Kolbeck C, Handel G, Schneider-Feyrer S, Behr M. Influence of the fabrication process on the in vitro performance of fixed dental prostheses with zirconia substructures. Clin Oral Investig 2011; 15 (06) 1007-1012
15 Lin J, Lin Z, Zheng Z. Effect of different restorative crown design and materials on stress distribution in endodontically treated molars: a finite element analysis study. BMC Oral Health 2020; 20 (01) 226
16 Pucci CR, Mafetano APVP, Borges ALS. et al. Substrate rigidity effect on CAD/CAM restorations at different thicknesses. Eur J Dent 2023; 17 (04) 1020-1028
17 Mathur VP, Atif M, Duggal I, Tewari N, Duggal R, Chawla A. Reporting guidelines for in-silico studies using finite element analysis in medicine (RIFEM). Comput Methods Programs Biomed 2022; 216: 106675
18 Hassouneh L, Matoug-Elwerfelli M, Al-Omari T, Setzer FC, Nagendrababu V. Assessment of biomechanical behavior of immature non-vital incisors with various treatment modalities by means of three-dimensional quasi-static finite element analysis. Sci Rep 2023; 13 (01) 17491
19 Abo-Alazm EAE, Abdou A, Hassouneh L, Safy RK. Reliability of an innovative slab shear versus microtensile bond strength test: mechanical and finite element analysis. Eur J Dent 2024; 18 (01) 182-195
20 Saber SM, Elashiry MM, Sadat SMAE, Nawar NN. A microcomputed tomographic analysis of the morphological variabilities and incidence of extra canals in mandibular first molar teeth in an Egyptian subpopulation. Sci Rep 2023; 13 (01) 8985
21 Wang Q, Liu Y, Wang Z. et al. Effect of access cavities and canal enlargement on biomechanics of endodontically treated teeth: a finite element analysis. J Endod 2020; 46 (10) 1501-1507
22 Abdelfattah RA, Nawar NN, Kataia EM, Saber SM. How loss of tooth structure impacts the biomechanical behavior of a single-rooted maxillary premolar: FEA. Odontology 2024; 112 (01) 279-286
23 Dimashkieh MR, Yousief SA, Demachkia AM. et al. Assessment of stress distribution around traditional and sleeve fixed partial denture designs: finite element analysis. Eur J Dent 2025; 19 (03) 667-677
24 Liu B, Lu C, Wu Y, Zhang X, Arola D, Zhang D. The effects of adhesive type and thickness on stress distribution in molars restored with all-ceramic crowns. J Prosthodont 2011; 20 (01) 35-44
25 Nawar NN, Elkholy MMA, Ha WN, Saber SM, Kim H-C. Optimum shaping parameters of the middle mesial canal in mandibular first molars: a finite element analysis study. J Endod 2023; 49 (05) 567-574
26 Nawar NN, Kataia M, Omar N, Kataia EM, Kim H-C. Biomechanical behavior and life span of maxillary molar according to the access preparation and pericervical dentin preservation: Finite element analysis. J Endod 2022; 48 (07) 902-908
27 Lise DP, Perdigão J, Van Ende A, Zidan O, Lopes GC. Microshear bond strength of resin cements to lithium disilicate substrates as a function of surface preparation. Oper Dent 2015; 40 (05) 524-532
28 Wan B, Chung BH, Zhang MR. et al. The effect of varying occlusal loading conditions on stress distribution in roots of sound and instrumented molar teeth: a finite element analysis. J Endod 2022; 48 (07) 893-901
29 Koc D, Dogan A, Bek B. Bite force and influential factors on bite force measurements: a literature review. Eur J Dent 2010; 4 (02) 223-232
30 Jansen van Vuuren L, Broadbent JM, Duncan WJ, Waddell JN. Maximum voluntary bite force, occlusal contact points and associated stresses on posterior teeth. J R Soc N Z 2020; 50 (01) 132-143
31 Plotino G, Grande NM, Isufi A. et al. Fracture strength of endodontically treated teeth with different access cavity designs. J Endod 2017; 43 (06) 995-1000
32 Aslan T, Esim E, Üstün Y, Dönmez Özkan H. Evaluation of stress distributions in mandibular molar teeth with different iatrogenic root perforations repaired with biodentine or mineral trioxide aggregate: a finite element analysis study. J Endod 2021; 47 (04) 631-640
33 Scotti N, Forniglia A, Tempesta RM. et al. Effects of fiber-glass-reinforced composite restorations on fracture resistance and failure mode of endodontically treated molars. J Dent 2016; 53: 82-87
34 Düzgün S, Esim E, Aslan T, Avcı ATE. Finite element analysis of stress in mandibular molars repaired after fractured instrument removal. BMC Oral Health 2025; 25 (01) 85
35 Saber SM, Hayaty DM, Nawar NN, Kim H-C. The effect of access cavity designs and sizes of root canal preparations on the biomechanical behavior of an endodontically treated mandibular first molar: a finite element analysis. J Endod 2020; 46 (11) 1675-1681
36 El Ghoul WA, Özcan M, Ounsi H, Tohme H, Salameh Z. Effect of different CAD-CAM materials on the marginal and internal adaptation of endocrown restorations: an in vitro study. J Prosthet Dent 2020; 123 (01) 128-134
37 Lee K-S, Shin J-H, Kim J-E. et al. Biomechanical evaluation of a tooth restored with high performance polymer PEKK post-core system: a 3D finite element analysis. BioMed Res Int 2017; 2017 (01) 1373127
38 Aslan T, Esim E, Üstün Y. Finite element evaluation of dentin stress changes following different endodontic surgical approaches. Odontology 2024; 112 (03) 798-810
39 Sira A, Nawar NN, Saber SM, Kim H-C. The effect of different separated file retrieval strategies on the biomechanical behavior of a mandibular molar: a finite element analysis study. J Endod 2024; 51 (01) 64-70
40 Özcan C, Lestriez P, Özcan M, Josset Y. Finite element analysis of dental structures: the role of mandibular kinematics and model complexity. Front Dent Med 2024; 5: 1461909
41 Shahmoradi M, Wan B, Zhang Z, Wilson T, Swain M, Li Q. Monolithic crowns fracture analysis: the effect of material properties, cusp angle and crown thickness. Dent Mater 2020; 36 (08) 1038-1051