In order to mimic the biomechanical behavior of dental tissues, the periodontal ligament (PDL) and alveolar bone are simulated in the FEA. FEA is a method widely used in dentistry that provides a vast array of possibilities to test materials and restorative options, that can be, to a great extent, extrapolated to the clinical setting 23, 24. Due to the complexity and ethical issues of clinical studies, it is advisable to first retrieve in vitro and FEA data on a certain topic.
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Hence, it is important to further investigate the causes underlying the more unpredictable clinical performance of endocrowns in premolars compared to molars. However, endocrowns seem to fail more frequently in premolars 22.
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Particularly, endocrown, introduced more than two decades ago 19 has shown promising results in terms of durability and ease of manufacturing and seems to be comparable to full crown restorations in terms of teeth survival rates and fracture resistance, especially in molars 20, 21. The advantage of composite restorations is their repairability and lower cost compared to the ceramic ones.ĬAD/CAM indirect restorations are chair-side solutions which reduce laboratory time and costs and are becoming increasingly present in daily clinical practice 18. Resin composites and adhesive systems have improved immensely since their first introduction to the dental field 11, 12 and can provide similar fracture resistance 13, 14, 15 and clinical survival 16, 17 compared to indirect ceramic restorations. Nowadays, in the era of minimally invasive dentistry, there has been a shift towards less invasive restorative solutions-Prevention of Extension instead of Extension for Prevention 10. Hence, to comply with the tendency for procedural simplification and tooth tissue preservation, the application of a post in teeth that exhibit coronal walls should be carefully reconsidered 9. This is particularly the case in teeth that present a ferrule effect, but no coronal walls 9. Clinically, several studies reported a positive impact of post placement on the survival of endodontically treated premolars 7, 8. Traditionally, metal-ceramic or all-ceramic full crowns have been used, often with a post as an additional element of retention 6. The definitive restoration of an endodontically treated tooth is of utmost importance for tooth survival and for the restitution of its biomechanical properties 2. Tissue loss has been appointed the main cause of deterioration of the biomechanical properties of endodontically treated teeth, particularly the loss of proximal ridges and access cavity preparation 2, 3, 4, 5.
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More conservative restorations seem a feasible alternative for endodontically treated premolars to conventional post-core-crown.Įndodontic therapy is usually indicated as a consequence of an extensive carious process or dental trauma, both leading to substantial tooth tissue loss 1, 2. B models demonstrated larger high stress areas in the root than PMMA models. C showed the lowest stress in dentin, while EC showed lower stresses and strains in crown cement. The highest stresses and strains in all FEA models were observed on occlusal and vestibular cervical surfaces, corresponding to fracture propagation demonstrated in vitro. Fracture resistance data were statistically analyzed ( p < 0.050). The same groups were further tested for static fracture resistance in vitro (n = 5, 6.0 mm-diameter ball indenter, vertical load). Von Mises stresses and strains were calculated. Models were two-point axially loaded occlusally (850 N). 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). A 3-D model of an endodontically treated premolar was created in Solidworks. 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.