Effect of Different Restorative Design on Stress Concentration of Lithium Disilicate and Monolithic Zirconia Endocrown- a Finite Element Analysis

Effect of Different Restorative Design on Stress Concentration of Lithium Disilicate and Monolithic Zirconia Endocrown- a Finite Element Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effect of Different Restorative Design on Stress Concentration of Lithium Disilicate and Monolithic Zirconia Endocrown- a Finite Element Analysis Dr. Garima Karn, Prof (Dr.) Manoj Shetty, Prof (Dr.) Chethan Hegde This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5278185/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 08 Feb, 2025 Read the published version in BMC Oral Health → Version 1 posted 11 You are reading this latest preprint version Abstract Background - The purpose of this simulation study was to evaluate effect of different restorative design on stress concentration endocrown of different restorative materials using a finite element analysis. Methods : A 3D FEA model of mandibular molar was constructed using the average values and was used in this analysis. 2 materials were used which were lithium disilicate and zirconia and 2 different margin design of knife edge and shoulder margins were used in various combinations of material and margin design. A constant 12° of internal wall angulation was considered for all the 4 models and a uniform cement thicknes of 100µm was considered. A uniform 2mm of bulk fill composite was used as a base beneath the endocrowns. 300 N load was applied on the cusps for each model and linear static analysis was carried out Results : Endocrowns of lithium disilicate was found to exert a greater stress concentration in comparison to zirconia endocrowns in both the margin designs of knife edge and shoulder. Knife edge margins were seen to yield greater stress concentration on the remaining tooth structure in comparison to shoulder margins in endocrowns of both the materials used. Conclusion : There is a positive influence of margin design selection within the same material used for the fabrication of endocrown. However the values found in the study may not lead to clinical/ catastrophic failure of the endocrown restorations. endocrown lithium disilicate zirconia endodontically treated teeth knife edge margins shoulder margins Figures Figure 1 Figure 2 Figure 3 Figure 4 BACKGROUND In dentistry, restoring severely damaged nonvital teeth is a difficult process [ 1 ]. It is challenging to assess the lifespan of teeth that have had endodontic treatment due to the numerous mitigating factors. Endodontically treated teeth is considered more brittle in comparison to a vital teeth due to decrease in the moisture content of dentin following extirpation of the vital pulp [ 2 ]. The access preparation also results in the loss of a proportion of structural integrity and this loss negatively affects the endodontically treated tooth's ability to withstand fractures [ 3 ]. It is also hypothesized that part of the sensory feedback mechanism is lost during the removal of the neurovascular pulpal tissue during root canal therapy as a result of which a person may unintentionally bite down on an endodontically treated tooth with a lot more force than on a vital tooth because of the compromised sensory feedback mechanism [ 4 ]. The pooled percentage of teeth that survived for two to ten years varied between 86% and 93% in a systematic review of tooth survival following nonsurgical root canal therapy that included 14 studies published between 1993 and 2007 in a study conducted by Ng YL et al [ 5 ]. Arguably the most important factor is the amount of coronal tooth structure that remains before the final restoration [ 6 , 7 ]. In a study conducted by Pantvisai P et al. evaluating cuspal deflection in molars in relation to endodontic and restorative procedures they concluded that cuspal deflection was highest after endodontic access and increased on subsequent enlargement of cavity [ 8 ]. The usual treatment option is a conventional crown becomes challenging when there is significant damage to the tooth structure. Taking support from the canal by removing the obturating material and giving a post followed by a post are core build up used to be the treatment of choice for rehabilitation of severely damaged teeth. However studies have shown greater stress accumulation on the remaining tooth structure with such a treatment option and is now considered to significantly weaken the root structure [ 7 ]. According to a study by Biacchi and Basting endodontically treated teeth restored with ceramic crowns held in place by fibre reinforced posts and core are more prone to fracture than those restored with endocrowns [ 9 ]. The focus on minimally invasive approaches and advancements in adhesive dentistry have led to the introduction of endocrown restorations as a substitute option for rehabilitation of severely damaged endodontically treated teeth. An endocrown restoration is a monolithic restoration that obtains both microretention (by utilizing adhesive cement) and macro-mechanical retention (given by the pulpal walls) by using the pulp chamber and remaining coronal tooth structure as a means of retention. Bindl and Mormann coined the term ―endocrown in 1999 [ 10 , 11 ]. Recently, endocrowns have been employed to offer a more conservative approach to treatment by avoiding the necessity for posts and/or substantial core build-ups [ 12 ]. Endocrowns are recommended in cases of molars with extensive loss of coronal tooth structure and limited interocclusal space, in which there is difficulty in gaining thickness of restorative material with ceramic layering on an underlining (metal or zirconia) substructures [ 13 ]. Various materials can be used for the fabrication of endocrown. Lithium disilicate is one of the material of choice due to its favourable physical properties, optimum aesthetics, and the advantage of its bonding to tooth structure [ 13 ]. However, it needs an extra step of crystallization when milled from ingots, which could result in an increase in marginal gaps [ 14 , 15 ]. Zirconia has gained popularity as the material of choice these days due to its superior toughness and fracture resistance in comparison to other ceramics [ 16 ]. However bonding of zirconia to tooth structure is questionable as has been reported as a material of high bond failure of the luting cement [ 17 ]. Various designs of endocrown preparation that have been used commonly include a butt design in which there is no circumferential preparation of the tooth to give a margin and it has been compared with a circumferential preparation to give a shoulder margin in a study conducted by Doaa Taha et al. and they concluded that in order to improve the fracture resistance of a teeth, a short axial wall and shoulder finish line might be added [ 18 ]. Alamin AM et al compared deep chamfer finish line to butt margins of endocrown and concluded that chamfer finish lines have shown greater fracture resistance in comparison to butt joint finish lines [ 19 ]. Abtahi S et al considered different internal wall divergences as 6°, 12° and 16° and concluded that the pulp chamber axial walls between 6◦ and 12◦ of divergence balances the stress magnitude. In endocrowns. They also concluded that bulk fill resin composite should be the material of choice as base to seal the orifice of the root canal when endocrown restorations are planned. Access cavity preparation leads to divergence of internal wall and therefore a constant 12° of divergence was considered for the study [ 20 ]. Typically shoulder margin is a choice but with advent of adhesive dentistry and materials like lithium disilicate that can be bonded to the tooth structure, knife edge margins are being considered as a viable option pertaining to it conservative preparation which preserves the bulk of the tooth structure. As is believed that conservation of tooth structure may improve the strength of tooth and its resistance to breakdown. Therefore the study was designed to evaluate both the commonly used materials that are lithium disilicate and monolithic zirconia and also compare knife edge margins with shoulder margins for stress concentration on the remaining tooth structure and to establish if knife edge margin can be used as a feasible margin design in restoring severely damaged non vital teeth using endocrowns. METHODS DESIGNING OF FINITE ELEMENT ANALYSIS MODEL: A CT scan data was read into MIMICS software and processed further to extract the region of interest for the study i.e. mandibular first molar. Crown was reconstructed using Hypermesh 2019 software. Material properties like Elastic modulus and poisons ratio was assigned for each part as in table 1. 12° angle of divergence of the pulp chamber, intracoronal extension of 6mm into the floor of the pulp chamber, 3.5mm occlusal clearance with 2 mm of ferrule width was common for all the designs. The 4 model designs were: 1. Model A- Knife edge preparation with 0.5 mm reduction at margins, made with lithium disilicate. 2. Model B- Knife edge preparation with 0.5 mm reduction at margins, made with monolithic zirconia. 3. Model C- Shoulder margin preparation with 1mm reduction at margins, made with lithium disilicate. 4. Model D- Shoulder margin preparation with 1mm reduction at margins, made with monolithic zirconia. All the models had 2mm of base of bulk-fill composite placed over the pulpal floor. Resin cement of uniform thickness of 100µm was used as shown in Figure 1. APPLICATION OF LOAD: Fe-model was then exported to ANSYS 2017.2: Analysis System Software for further analysis 300 N load was applied on the cusps for each model (3 on each buccal cusps’ outer aspects (functional cusp) and 2 on lingual cusps’ inner aspects (nonfunctional cusp) and linear static analysis was carried out as shown in Figure 2. Results like, displacement and stresses were extracted and documented for all four cases. RESULTS Case 1- Knife edge margins Maximum stress is observed at the loading points of the crown and with lithium disilicate endocrown. Maximum stress is observed at the distal region of the cement, shown in figure 3. Material Von-mises stress (MP a) Lithium disilicate Zirconia Crown 56.57 50.56 Cement 0.09 0.054 Enamel/dentin 6.66 6.07 PDL 0.023 0.021 Cortical bone 10.2 9.03 Cancellous bone 1.36 1.2 GP 0.131 0.115 Case- 2- Shoulder margin model- Maximum stress is observed at the loading points of the crown and with lithium disilicate Crown. Maximum stress is observed at the distal region of the cement as shown in figure 4. Material Von-mises stress (MP a) Lithium disilicate Zirconia Crown 60.4 53.55 Cement 0.076 0.04 Dentine 6.094 5.481 PDL 0.019 0.018 Cortical bone 11.33 10.14 Cancellous bone 1.51 1.35 GP 0.155 0.148 STATISTICAL ANALYSES: The statistical analysis for this study involved conducting a one-sample t-test to examine the dataset. Within knife-edge margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress on the remaining tooth structure in comparison to zirconia endocrown. The results were statistically not significant. Within shoulder margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress in comparison to zirconia endocrowns. The results were statistically not significant. Results are depicted in table 2,3,4,5 DISCUSSION A crown of endodontically treated tooth's long-term survival depends on the presence of sufficient circumferential tooth structure (ferrule) at the crown-root interface. The final restoration improves the stability of the endodontically treated tooth by acting as a bracing, casing, or hugging mechanism [21]. An endocrown is a complete crown that extends into the pulp chamber and gains additional retention from it and therefore serves as a "monoblock", negating the necessity for an intraradicular post [ 22 ]. The clinical efficacy and longevity of endocrown- an adhesive and conservative coronal restoration, are contingent upon the mechanical characteristics of the restorative materials in addition to the available design parameters. Because of its efficacy and standardization, finite element analysis (FEA) has been employed in dentistry to assess the stress distributions caused by masticatory loads. It can identify areas of high stress where failure of the restoration could happen. According to Tortopidis et al., the maximum masticatory load in the posterior region for healthy adults is 580 N [ 23 ]. In a study by Bakke et al., different average magnitudes of greatest masticatory loads were reported in males (522 N) and females (441 N) [ 24 ]. 30 In this study an attempt was made to compare the commonly employed shoulder margin for the preparation of endocrowns with knife edge margins which has become a viable option these days due to the advent of adhesive dentistry and also compare two materials- Zr and LiDi The applied axial force in this investigation was 300 N. In a study conducted by Mohammed Abu Helal et al in the year 2017 [ 1 ], values of stress concentration on the dentin structure in an intact tooth structure was found to be 3.54 MPa in comparison to the 10.8 MPa found in endodontically treated teeth restored with endocrown and 12.2 MPa in an endodontically treated teeth restored with a conventional ceramic crown with post and core. In this study the stress concentration values were found to be lesser in comparison to the mentioned study and the values ranged from 5.48 MPa- 6.66 MPa which may be attributed to the choice of material used. Post and core retained conventional crowns was concluded in various studies to have greater concentration of stress on the remaining tooth structure in comparison to various designs of the endocrown and therefore was not used as a criteria for comparison in this study. Shoulder margins exhibited a wider surface contact of restoration to tooth structure leading to distribution of the forces over a wider surface area and therefore can be explained by the results obtained of lesser stress concentration on the remaining tooth structure using both the restorative material in this study. Valenti M et al in a retrospective study [ 26 ] evaluating survival of 110 lithium disilicate crowns with feather-edge margin preparation concluded that vertical finish line used in single crown restoration exhibited a low clinical failure rate upto 9 years (overall survival probability was 96.1%) and therefore in the study it was concluded that lithium disilicate can be used as the material of choice in vertical preparation margin designs like feather edge and knife- edge. Group I with knife edge margins exhibited statistically significant (0.013) higher stress concentration on the remaining tooth structure in lithium disilicate endocrowns in comparison to zirconia endocrowns. Similar results were seen in Group II with shoulder margins (0.014). Decreased stress concentration in zirconia in comparison to lithium disilicate can be attributed to lower resilience, resulting in lower force absorbing capacity in lithium disilicate. Although Zirconia leads to wear of the antagonistic tooth more than those with lithium disilicate pertaining to its greater hardness (Li: HV 600, Zr: HV 1200–1300, enamel: HV 300–400) and flexural strength (Li: < 500 MPa, Zr: 1200 MPa, enamel 300–450 MPa) [ 26 ]. The results indicating a higher concentration of stress on the distal portion of the prepared tooth structure can be justified by taking into account the distal curvatures of the mesial and distal roots of the mandibular molar, Curve of Spee and the arc of closure of the mandible in which the teeth and cusps closer to the condylar head experience greater bite force and come in contact with the opposing cups earlier in comparison to the mesial cusps of a tooth. Therefore when designing an endocrown lighter occlusal contacts must be given in the distal part of the restoration in comparison to the mesial part in order to prevent the deleterious effect of greater forces which may lead to debonding of the restorations. Conclusion Within the limitations of this study we conclude that: 1. Von mises stress was found to be of greater value on the prepared tooth structure (dentin) with lithium disilicate endocrowns in comparison to zirconia endocrowns in both knife-edge and shoulder margin preparations. The results were statistically significant . 2. Within knife-edge margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress on the remaining tooth structure in comparison to zirconia endocrown. The results were statistically not significant. 3. Within shoulder margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress in comparison to zirconia endocrowns. The results were statistically not significant. 4. Knife- edge margins exhibited a greater von-mises stress values in comparison to shoulder edge margin designs of endocrown. Declarations Ethics approval and consent to participate - Received clearance from institutional ethical committee. Ref.No. ETHICS/ABSMIDS/232/2022 Consent for publication- Not applicable Availability of data and materials- The data presented in this study are available on request from the corresponding author Competing interests- The authors declare that they have no competing interests Funding- This research received no external funding. Authors' contributions- GK conceived and designed the study and wrote the paper. ZZ reviewed and edited the manuscript. All authors have read and agreed to the published version of the manuscript. Acknowledgements- Roopesh Kumar Chinappa performed the finite element analysis. References Helal MA, Wang Z. Biomechanical assessment of restored mandibular molar by endocrown in comparison to a glass fiber post‐retained conventional crown: 3D finite element analysis. Journal of Prosthodontics. 2019 Dec;28(9):988-96. Helfer AR, Melnick S, Schilder H. Determination of the moisture content of vital and pulpless teeth. Oral Surgery, Oral Medicine, Oral Pathology. 1972 Oct 1;34(4):661-70. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. Journal of endodontics. 1989 Nov 1;15(11):512-6. Randow K, Glantz P. On cantilever loading of vital and non-vital teeth. Acta Odontol Scand 1986;44:271–7. Ng YL, Mann V, Gulabivala K. Tooth survival following non‐surgical root canal treatment: a systematic review of the literature. International endodontic journal. 2010 Mar;43(3):171-89. Robbins JW. Restoration of the endodontically treated tooth. Dental Clinics. 2002 Apr 1;46(2):367-84. 5 Dorothy McComb BD, MScD FR. Restoration of the endodontically treated tooth. Ensuring Continued Trust. 2008. Pantvisai P, Messer HH. Cuspal deflection in molars in relation to endodontic and restorative procedures. Journal of endodontics. 1995 Feb 1;21(2):57-61. Biacchi GR, Basting RT: Comparison of fracture strength of endocrowns and glass fiber post-retained conventional crowns. Oper Dent 2012;37:130-136 Bindl A, Mormann WH Clinical evaluation of adhesively placed Cerec endocrowns after 2 years--preliminary results. J Adhes Dent (1999) 1: 255- 265 Belleflamme MM, Geerts SO, Louwette MM, et al: No post-no core approach to restore severely damaged posterior teeth: An up to 10-year retrospective study of documented endocrown cases. J Dent 2017;63:1-7 Al-Dabbagh RA: Survival and success of endocrowns: A systematic review and meta-analysis. J Prosthet Dent 2021;125:415.e411-415.e419 El Makawi Y, Khattab N. In vitro comparative analysis of fracture resistance of lithium disilicate endocrown and prefabricated zirconium crown in pulpotomized primary molars. Open access Macedonian journal of medical sciences. 2019 Dec 12;7(23):4094. Pieger S, Salman A, Bidra AS: Clinical outcomes of lithium disilicate single crowns and partial fixed dental prostheses: a systematic review. J Prosthet Dent 2014;112:22-30 Gold SA, Ferracane JL, da Costa J: Effect of Crystallization Firing on Marginal Gap of CAD/CAM Fabricated Lithium Disilicate Crowns. J Prosthodont 2018;27:63-66. Kim JH, Oh S, Uhm SH: Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns. Biomed Res Int 2016;2016:8635483 Dal Piva AM, Tribst JP, Borges AL, e Souza RO, Bottino MA. CAD-FEA modeling and analysis of different full crown monolithic restorations. Dental Materials. 2018 Sep 1;34(9):1342-50. Taha D, Spintzyk S, Schille C, Sabet A, Wahsh M, Salah T, Geis-Gerstorfer J. Fracture resistance and failure modes of polymer infiltrated ceramic endocrown restorations with variations in margin design and occlusal thickness. Journal of prosthodontic research. 2018;62(3):293-7. Alamin AM, Sakrana AA, Al-Zordk WA. Impact of marginal preparation design on the fracture resistance of endo-crown all-ceramic. IOSR J Dent Med Sci. 2019;18:11-7. Abtahi S, Alikhasi M, Siadat H. Biomechanical behavior of endocrown restorations with different cavity design and CAD-CAM materials under a static and vertical load: A finite element analysis. The Journal of Prosthetic Dentistry. 2022 Apr 1;127(4):600-e1 Deutsch AS, Musikant BL. Morphological measurements of anatomic landmarks in human maxillary and mandibular molar pulp chambers. Journal of endodontics. 2004 Jun 1;30(6):388-90. Otto T: Computer-aided direct all-ceramic crowns: preliminary 1-year results of a prospective clinical study. Int J Period Restor Dent 2004;24:446-455 Tortopidis D, Lyons MF, Baxendale RH, et al: The variability of bite force measurement between sessions, in different positions within the dental arch. J Oral Rehabil 1998;25:681-686 Bakke M, Michler L, Moller E: Occlusal control of mandibular elevator muscles. Scan J Dent Res 1992;100:284-291 Sichi LG, Pierre FZ, Arcila LV, de Andrade GS, Tribst JP, Ausiello P, Di Lauro AE, Borges AL. Effect of biologically oriented preparation technique on the stress concentration of endodontically treated upper central incisor restored with zirconia crown: 3d-fea. Molecules. 2021 Oct 10;26(20):6113. Valenti M, Valenti A. Retrospective survival analysis of 110 lithium disilicate crowns with feather-edge marginal preparation. International Journal of Esthetic Dentistry. 2015 Jun 1;10(2). Tables Table 1 MATERIAL ELASTIC MODULUS(Mpa) Poisson’s ratio Enamel 84.10 0.33 Dentine 0.33 18 Periodontal ligament 0.45 0.069 Cortical bone 13.7 0.30 Cancellous bone 1.37 0.30 Lithium disilicate 95 0.30 Monolithic zirconia 200 0.31 Gutta percha 0.69 × 10 -3 0.45 Resin cement 6.6 0.35 Bulk-fill composite 13.46 0.18 Table 2 Group I (Knife edge margins) (Von Mises stress (Mpa)) LiDi Zirconia p value Crown 56.57 50.56 0.007* Cement 0.09 0.054 0.449 Dentine 6.66 6.07 0.013* PDL 0.023 0.021 0.8 Cortical Bone 10.2 9.03 0.002* Cancellous Bone 1.36 1.2 0.323 GP 0.131 0.115 0.635 Table 3 Group II (shoulder margin) (Von Mises stress (Mpa)) LiDi Zirconia p value Crown 60.4 53.55 0.156 Cement 0.076 0.04 0.495 Dentine 6.094 5.481 0.014* PDL 0.019 0.018 0.373 Cortical Bone 11.33 10.14 0.001* Cancellous Bone 1.51 1.35 0.156 GP 0.155 0.148 0.861 Table 4 LiDi (Von Mises stress (Mpa)) Group I Group II p value Crown 56.57 60.4 0.095 Cement 0.09 0.076 0.606 Dentine 6.66 6.094 0.334 PDL 0.023 0.019 0.605 Cortical Bone 10.2 11.33 0.032* Cancellous Bone 1.36 1.51 0.336 GP 0.131 0.155 0.764 Table 5 Zirconia (Von Mises stress (Mpa)) Group I Group II p value Crown 50.56 53.55 0.266 Cement 0.054 0.04 0.597 Dentine 6.07 5.481 0.346 PDL 0.021 0.018 0.705 Cortical Bone 9.03 10.14 0.025* Cancellous Bone 1.2 1.35 0.34 GP 0.115 0.148 0.696 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 08 Feb, 2025 Read the published version in BMC Oral Health → Version 1 posted Editorial decision: Revision requested 21 Nov, 2024 Reviews received at journal 26 Oct, 2024 Reviewers agreed at journal 26 Oct, 2024 Reviewers agreed at journal 23 Oct, 2024 Reviews received at journal 23 Oct, 2024 Reviewers agreed at journal 23 Oct, 2024 Reviewers invited by journal 23 Oct, 2024 Editor invited by journal 18 Oct, 2024 Editor assigned by journal 17 Oct, 2024 Submission checks completed at journal 17 Oct, 2024 First submitted to journal 16 Oct, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5278185","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":370789469,"identity":"ee9c0171-5eb3-4a20-8161-de52a62b4892","order_by":0,"name":"Dr. Garima Karn","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDElEQVRIiWNgGAWjYJCCAwwMCUCK+eCDDxU2QAZj4wEitbAlG844kwbS0kBQCwNEC4+ZNG/LYZghuIG8+9mHh27UpMmbz24Aamk4b7e2/TDQlhqbaFxaDM+kGxzOOZZjOOfOgWTLuTtuJ287kwjUciwttwGXloY0hsM5bBWMMyQSDt54e+Z2stkBoBbGhsO4tfQ/A2r5V2E/QyKxQYK37Vyy2fmH+LXISwBtyW3LSZwhkcwkydt2wM7sBgFbDCSAtuT2pSXPkEhjBgZycoLZDaAtCXj8It+fxvw551uy7QyJ/I/AqLSzNzuf/vDBhxob3LYcQBNIBKtMwKEcbAu6WfZ4FI+CUTAKRsEIBQBBCmv6WmmwtQAAAABJRU5ErkJggg==","orcid":"","institution":"AB Shetty Memorial Institute of Dental sciences, Mangalore, India","correspondingAuthor":true,"prefix":"Dr.","firstName":"Garima","middleName":"","lastName":"Karn","suffix":""},{"id":370789470,"identity":"ff16a954-44d1-4eff-b5f1-aeb06b152815","order_by":1,"name":"Prof (Dr.) Manoj Shetty","email":"","orcid":"","institution":"AB Shetty Memorial Institute of Dental sciences, Mangalore, India","correspondingAuthor":false,"prefix":"","firstName":"Prof","middleName":"(Dr.) Manoj","lastName":"Shetty","suffix":""},{"id":370789471,"identity":"36621d4a-fe25-40c5-b761-2c3d9ea053d2","order_by":2,"name":"Prof (Dr.) Chethan Hegde","email":"","orcid":"","institution":"AB Shetty Memorial Institute of Dental sciences, Mangalore, India","correspondingAuthor":false,"prefix":"","firstName":"Prof","middleName":"(Dr.) Chethan","lastName":"Hegde","suffix":""}],"badges":[],"createdAt":"2024-10-16 19:53:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5278185/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5278185/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12903-024-05358-4","type":"published","date":"2025-02-08T15:57:16+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":67716288,"identity":"31a5f56c-3af9-41d5-889d-a987b2c5ac0d","added_by":"auto","created_at":"2024-10-29 04:06:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":316911,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend.\u003c/p\u003e","description":"","filename":"Picture1.png","url":"https://assets-eu.researchsquare.com/files/rs-5278185/v1/c67559c28ff48f83df40065c.png"},{"id":67716186,"identity":"fddd46b0-6037-4647-904f-2d5784feed60","added_by":"auto","created_at":"2024-10-29 03:58:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":38282,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend.\u003c/p\u003e","description":"","filename":"Picture2.png","url":"https://assets-eu.researchsquare.com/files/rs-5278185/v1/a416995ad6be3f0cb86eb137.png"},{"id":67716188,"identity":"38a8a57c-c2d1-4fe1-8fbf-370472a92b39","added_by":"auto","created_at":"2024-10-29 03:58:34","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":333826,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend.\u003c/p\u003e","description":"","filename":"Picture3.png","url":"https://assets-eu.researchsquare.com/files/rs-5278185/v1/75264d0f92e0a3e77c6f178a.png"},{"id":67716189,"identity":"38772959-a6e3-407f-b38f-7121ff30d341","added_by":"auto","created_at":"2024-10-29 03:58:35","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":278145,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend.\u003c/p\u003e","description":"","filename":"Picture4.png","url":"https://assets-eu.researchsquare.com/files/rs-5278185/v1/87d0931d43c442af672e3982.png"},{"id":75930008,"identity":"eb21f1b1-9540-4784-9cf2-ac914c97adb5","added_by":"auto","created_at":"2025-02-10 16:10:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1546643,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5278185/v1/3424612b-65af-4f41-9cd7-37a4abf2ec82.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eEffect of Different Restorative Design on Stress Concentration of Lithium Disilicate and Monolithic Zirconia Endocrown- a Finite Element Analysis\u003c/p\u003e","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eIn dentistry, restoring severely damaged nonvital teeth is a difficult process [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. It is challenging to assess the lifespan of teeth that have had endodontic treatment due to the numerous mitigating factors. Endodontically treated teeth is considered more brittle in comparison to a vital teeth due to decrease in the moisture content of dentin following extirpation of the vital pulp [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The access preparation also results in the loss of a proportion of structural integrity and this loss negatively affects the endodontically treated tooth's ability to withstand fractures [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. It is also hypothesized that part of the sensory feedback mechanism is lost during the removal of the neurovascular pulpal tissue during root canal therapy as a result of which a person may unintentionally bite down on an endodontically treated tooth with a lot more force than on a vital tooth because of the compromised sensory feedback mechanism [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The pooled percentage of teeth that survived for two to ten years varied between 86% and 93% in a systematic review of tooth survival following nonsurgical root canal therapy that included 14 studies published between 1993 and 2007 in a study conducted by Ng YL et al [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Arguably the most important factor is the amount of coronal tooth structure that remains before the final restoration [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In a study conducted by Pantvisai P et al. evaluating cuspal deflection in molars in relation to endodontic and restorative procedures they concluded that cuspal deflection was highest after endodontic access and increased on subsequent enlargement of cavity [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The usual treatment option is a conventional crown becomes challenging when there is significant damage to the tooth structure. Taking support from the canal by removing the obturating material and giving a post followed by a post are core build up used to be the treatment of choice for rehabilitation of severely damaged teeth. However studies have shown greater stress accumulation on the remaining tooth structure with such a treatment option and is now considered to significantly weaken the root structure [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. According to a study by Biacchi and Basting endodontically treated teeth restored with ceramic crowns held in place by fibre reinforced posts and core are more prone to fracture than those restored with endocrowns [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The focus on minimally invasive approaches and advancements in adhesive dentistry have led to the introduction of endocrown restorations as a substitute option for rehabilitation of severely damaged endodontically treated teeth. An endocrown restoration is a monolithic restoration that obtains both microretention (by utilizing adhesive cement) and macro-mechanical retention (given by the pulpal walls) by using the pulp chamber and remaining coronal tooth structure as a means of retention. Bindl and Mormann coined the term ―endocrown in 1999 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Recently, endocrowns have been employed to offer a more conservative approach to treatment by avoiding the necessity for posts and/or substantial core build-ups [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Endocrowns are recommended in cases of molars with extensive loss of coronal tooth structure and limited interocclusal space, in which there is difficulty in gaining thickness of restorative material with ceramic layering on an underlining (metal or zirconia) substructures [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Various materials can be used for the fabrication of endocrown. Lithium disilicate is one of the material of choice due to its favourable physical properties, optimum aesthetics, and the advantage of its bonding to tooth structure [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. However, it needs an extra step of crystallization when milled from ingots, which could result in an increase in marginal gaps [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Zirconia has gained popularity as the material of choice these days due to its superior toughness and fracture resistance in comparison to other ceramics [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. However bonding of zirconia to tooth structure is questionable as has been reported as a material of high bond failure of the luting cement [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Various designs of endocrown preparation that have been used commonly include a butt design in which there is no circumferential preparation of the tooth to give a margin and it has been compared with a circumferential preparation to give a shoulder margin in a study conducted by Doaa Taha et al. and they concluded that in order to improve the fracture resistance of a teeth, a short axial wall and shoulder finish line might be added [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Alamin AM et al compared deep chamfer finish line to butt margins of endocrown and concluded that chamfer finish lines have shown greater fracture resistance in comparison to butt joint finish lines [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Abtahi S et al considered different internal wall divergences as 6\u0026deg;, 12\u0026deg; and 16\u0026deg; and concluded that the pulp chamber axial walls between 6◦ and 12◦ of divergence balances the stress magnitude. In endocrowns. They also concluded that bulk fill resin composite should be the material of choice as base to seal the orifice of the root canal when endocrown restorations are planned. Access cavity preparation leads to divergence of internal wall and therefore a constant 12\u0026deg; of divergence was considered for the study [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Typically shoulder margin is a choice but with advent of adhesive dentistry and materials like lithium disilicate that can be bonded to the tooth structure, knife edge margins are being considered as a viable option pertaining to it conservative preparation which preserves the bulk of the tooth structure. As is believed that conservation of tooth structure may improve the strength of tooth and its resistance to breakdown. Therefore the study was designed to evaluate both the commonly used materials that are lithium disilicate and monolithic zirconia and also compare knife edge margins with shoulder margins for stress concentration on the remaining tooth structure and to establish if knife edge margin can be used as a feasible margin design in restoring severely damaged non vital teeth using endocrowns.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003eDESIGNING OF FINITE ELEMENT ANALYSIS MODEL: A CT scan data was read into MIMICS software and processed further to extract the region of interest for the study i.e. mandibular first molar. Crown was reconstructed using Hypermesh 2019 software. Material properties like Elastic modulus and poisons ratio was assigned for each part as in table 1. 12\u0026deg; angle of divergence of the pulp chamber, intracoronal extension of 6mm into the floor of the pulp chamber, 3.5mm occlusal clearance with 2 mm of ferrule width was common for all the designs.\u003c/p\u003e\n\u003cp\u003eThe 4 model designs were:\u003c/p\u003e\n\u003cp\u003e1. Model A- Knife edge preparation with 0.5 mm reduction at margins, made with lithium disilicate.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e2. Model B- Knife edge preparation with 0.5 mm reduction at margins, made with monolithic zirconia.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3. Model C- Shoulder margin preparation with 1mm reduction at margins, made with lithium disilicate.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e4. Model D- Shoulder margin preparation with 1mm reduction at margins, made with monolithic zirconia.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll the models had 2mm of base of bulk-fill composite placed over the pulpal floor. Resin cement of uniform thickness of 100\u0026micro;m was used as shown in Figure 1.\u003c/p\u003e\n\u003cp\u003eAPPLICATION OF LOAD: Fe-model was then exported to ANSYS 2017.2: Analysis System Software for further analysis 300 N load was applied on the cusps for each model (3 on each buccal cusps\u0026rsquo; outer aspects (functional cusp) and 2 on lingual cusps\u0026rsquo; inner aspects (nonfunctional cusp) and linear static analysis was carried out as shown in Figure 2. Results like, displacement and stresses were extracted and documented for all four cases.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eCase 1- Knife edge margins\u003c/p\u003e\n\u003cp\u003eMaximum stress is observed at the loading points of the crown and with lithium disilicate endocrown. Maximum stress is observed at the distal region of the cement, shown in figure 3.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"288\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003eMaterial\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 175px;\"\u003e\n \u003cp\u003eVon-mises stress (MP a)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eLithium disilicate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003eZirconia\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCrown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e56.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003e50.56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003e0.054\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eEnamel/dentin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e6.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003e6.07\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003ePDL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003e0.021\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCortical bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e10.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003e9.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCancellous bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eGP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 52px;\"\u003e\n \u003cp\u003e0.115\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eCase- 2- Shoulder margin model-\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMaximum stress is observed at the loading points of the crown and with lithium disilicate Crown. Maximum stress is observed at the distal region of the cement as shown in figure 4.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"298\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Material\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 185px;\"\u003e\n \u003cp\u003eVon-mises stress (MP a)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eLithium disilicate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003eZirconia\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCrown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e60.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e53.55\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eDentine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e6.094\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e5.481\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003ePDL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.019\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.018\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCortical bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e11.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e10.14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eCancellous bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 113px;\"\u003e\n \u003cp\u003eGP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0.148\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eSTATISTICAL ANALYSES:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe statistical analysis for this study involved conducting a one-sample t-test to examine the dataset. Within knife-edge margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress on the remaining tooth structure in comparison to zirconia endocrown. The results were statistically not significant. Within shoulder margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress in comparison to zirconia endocrowns. The results were statistically not significant.\u003c/p\u003e\n\u003cp\u003eResults are depicted in table 2,3,4,5\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eA crown of endodontically treated tooth's long-term survival depends on the presence of sufficient circumferential tooth structure (ferrule) at the crown-root interface. The final restoration improves the stability of the endodontically treated tooth by acting as a bracing, casing, or hugging mechanism [21]. An endocrown is a complete crown that extends into the pulp chamber and gains additional retention from it and therefore serves as a \"monoblock\", negating the necessity for an intraradicular post [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The clinical efficacy and longevity of endocrown- an adhesive and conservative coronal restoration, are contingent upon the mechanical characteristics of the restorative materials in addition to the available design parameters. Because of its efficacy and standardization, finite element analysis (FEA) has been employed in dentistry to assess the stress distributions caused by masticatory loads. It can identify areas of high stress where failure of the restoration could happen. According to Tortopidis et al., the maximum masticatory load in the posterior region for healthy adults is 580 N [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In a study by Bakke et al., different average magnitudes of greatest masticatory loads were reported in males (522 N) and females (441 N) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. 30 In this study an attempt was made to compare the commonly employed shoulder margin for the preparation of endocrowns with knife edge margins which has become a viable option these days due to the advent of adhesive dentistry and also compare two materials- Zr and LiDi The applied axial force in this investigation was 300 N. In a study conducted by Mohammed Abu Helal et al in the year 2017 [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], values of stress concentration on the dentin structure in an intact tooth structure was found to be 3.54 MPa in comparison to the 10.8 MPa found in endodontically treated teeth restored with endocrown and 12.2 MPa in an endodontically treated teeth restored with a conventional ceramic crown with post and core. In this study the stress concentration values were found to be lesser in comparison to the mentioned study and the values ranged from 5.48 MPa- 6.66 MPa which may be attributed to the choice of material used. Post and core retained conventional crowns was concluded in various studies to have greater concentration of stress on the remaining tooth structure in comparison to various designs of the endocrown and therefore was not used as a criteria for comparison in this study. Shoulder margins exhibited a wider surface contact of restoration to tooth structure leading to distribution of the forces over a wider surface area and therefore can be explained by the results obtained of lesser stress concentration on the remaining tooth structure using both the restorative material in this study. Valenti M et al in a retrospective study [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e26\u003c/span\u003e] evaluating survival of 110 lithium disilicate crowns with feather-edge margin preparation concluded that vertical finish line used in single crown restoration exhibited a low clinical failure rate upto 9 years (overall survival probability was 96.1%) and therefore in the study it was concluded that lithium disilicate can be used as the material of choice in vertical preparation margin designs like feather edge and knife- edge. Group I with knife edge margins exhibited statistically significant (0.013) higher stress concentration on the remaining tooth structure in lithium disilicate endocrowns in comparison to zirconia endocrowns. Similar results were seen in Group II with shoulder margins (0.014). Decreased stress concentration in zirconia in comparison to lithium disilicate can be attributed to lower resilience, resulting in lower force absorbing capacity in lithium disilicate. Although Zirconia leads to wear of the antagonistic tooth more than those with lithium disilicate pertaining to its greater hardness (Li: HV 600, Zr: HV 1200\u0026ndash;1300, enamel: HV 300\u0026ndash;400) and flexural strength (Li: \u0026lt; 500 MPa, Zr: 1200 MPa, enamel 300\u0026ndash;450 MPa) [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The results indicating a higher concentration of stress on the distal portion of the prepared tooth structure can be justified by taking into account the distal curvatures of the mesial and distal roots of the mandibular molar, Curve of Spee and the arc of closure of the mandible in which the teeth and cusps closer to the condylar head experience greater bite force and come in contact with the opposing cups earlier in comparison to the mesial cusps of a tooth. Therefore when designing an endocrown lighter occlusal contacts must be given in the distal part of the restoration in comparison to the mesial part in order to prevent the deleterious effect of greater forces which may lead to debonding of the restorations.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWithin the limitations of this study we conclude that:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e1. Von mises stress was found to be of greater value on the prepared tooth structure (dentin) with lithium disilicate endocrowns in comparison to zirconia endocrowns in both knife-edge and shoulder margin preparations. The results were statistically significant .\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e2. Within knife-edge margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress on the remaining tooth structure in comparison to zirconia endocrown. The results were statistically not significant.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3. Within shoulder margin, Lithium disilicate endocrown was found to have a greater value of von-mises stress in comparison to zirconia endocrowns. The results were statistically not significant.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e4. Knife- edge margins exhibited a greater von-mises stress values in comparison to shoulder edge margin designs of endocrown.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e- Received clearance from institutional ethical committee. Ref.No. ETHICS/ABSMIDS/232/2022\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication-\u003c/strong\u003e Not applicable\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials-\u003c/strong\u003e The data presented in this study are available on request from the corresponding author\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests-\u003c/strong\u003e The authors declare that they have no competing interests\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding-\u003c/strong\u003e This research received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions-\u0026nbsp;\u003c/strong\u003eGK conceived and designed the study and wrote the paper. ZZ reviewed and edited the manuscript. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements-\u003c/strong\u003e Roopesh Kumar Chinappa performed the finite element analysis.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHelal MA, Wang Z. Biomechanical assessment of restored mandibular molar by endocrown in comparison to a glass fiber post‐retained conventional crown: 3D finite element analysis. Journal of Prosthodontics. 2019 Dec;28(9):988-96. \u003c/li\u003e\n\u003cli\u003eHelfer AR, Melnick S, Schilder H. Determination of the moisture content of vital and pulpless teeth. Oral Surgery, Oral Medicine, Oral Pathology. 1972 Oct 1;34(4):661-70. \u003c/li\u003e\n\u003cli\u003eReeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. Journal of endodontics. 1989 Nov 1;15(11):512-6. \u003c/li\u003e\n\u003cli\u003eRandow K, Glantz P. On cantilever loading of vital and non-vital teeth. Acta Odontol Scand 1986;44:271\u0026ndash;7. \u003c/li\u003e\n\u003cli\u003eNg YL, Mann V, Gulabivala K. Tooth survival following non‐surgical root canal treatment: a systematic review of the literature. International endodontic journal. 2010 Mar;43(3):171-89. \u003c/li\u003e\n\u003cli\u003eRobbins JW. Restoration of the endodontically treated tooth. Dental Clinics. 2002 Apr 1;46(2):367-84. 5 \u003c/li\u003e\n\u003cli\u003eDorothy McComb BD, MScD FR. Restoration of the endodontically treated tooth. Ensuring Continued Trust. 2008. \u003c/li\u003e\n\u003cli\u003ePantvisai P, Messer HH. Cuspal deflection in molars in relation to endodontic and restorative procedures. Journal of endodontics. 1995 Feb 1;21(2):57-61. \u003c/li\u003e\n\u003cli\u003eBiacchi GR, Basting RT: Comparison of fracture strength of endocrowns and glass fiber post-retained conventional crowns. Oper Dent 2012;37:130-136\u003c/li\u003e\n\u003cli\u003eBindl A, Mormann WH Clinical evaluation of adhesively placed Cerec endocrowns after 2 years--preliminary results. J Adhes Dent (1999) 1: 255- 265 \u003c/li\u003e\n\u003cli\u003eBelleflamme MM, Geerts SO, Louwette MM, et al: No post-no core approach to restore severely damaged posterior teeth: An up to 10-year retrospective study of documented endocrown cases. J Dent 2017;63:1-7 \u003c/li\u003e\n\u003cli\u003eAl-Dabbagh RA: Survival and success of endocrowns: A systematic review and meta-analysis. J Prosthet Dent 2021;125:415.e411-415.e419 \u003c/li\u003e\n\u003cli\u003eEl Makawi Y, Khattab N. In vitro comparative analysis of fracture resistance of lithium disilicate endocrown and prefabricated zirconium crown in pulpotomized primary molars. Open access Macedonian journal of medical sciences. 2019 Dec 12;7(23):4094. \u003c/li\u003e\n\u003cli\u003ePieger S, Salman A, Bidra AS: Clinical outcomes of lithium disilicate single crowns and partial fixed dental prostheses: a systematic review. J Prosthet Dent 2014;112:22-30 \u003c/li\u003e\n\u003cli\u003eGold SA, Ferracane JL, da Costa J: Effect of Crystallization Firing on Marginal Gap of CAD/CAM Fabricated Lithium Disilicate Crowns. J Prosthodont 2018;27:63-66. \u003c/li\u003e\n\u003cli\u003eKim JH, Oh S, Uhm SH: Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns. Biomed Res Int 2016;2016:8635483 \u003c/li\u003e\n\u003cli\u003eDal Piva AM, Tribst JP, Borges AL, e Souza RO, Bottino MA. CAD-FEA modeling and analysis of different full crown monolithic restorations. Dental Materials. 2018 Sep 1;34(9):1342-50.\u003c/li\u003e\n\u003cli\u003eTaha D, Spintzyk S, Schille C, Sabet A, Wahsh M, Salah T, Geis-Gerstorfer J. Fracture resistance and failure modes of polymer infiltrated ceramic endocrown restorations with variations in margin design and occlusal thickness. Journal of prosthodontic research. 2018;62(3):293-7. \u003c/li\u003e\n\u003cli\u003eAlamin AM, Sakrana AA, Al-Zordk WA. Impact of marginal preparation design on the fracture resistance of endo-crown all-ceramic. IOSR J Dent Med Sci. 2019;18:11-7.\u003c/li\u003e\n\u003cli\u003eAbtahi S, Alikhasi M, Siadat H. Biomechanical behavior of endocrown restorations with different cavity design and CAD-CAM materials under a static and vertical load: A finite element analysis. The Journal of Prosthetic Dentistry. 2022 Apr 1;127(4):600-e1\u003c/li\u003e\n\u003cli\u003eDeutsch AS, Musikant BL. Morphological measurements of anatomic landmarks in human maxillary and mandibular molar pulp chambers. Journal of endodontics. 2004 Jun 1;30(6):388-90. \u003c/li\u003e\n\u003cli\u003eOtto T: Computer-aided direct all-ceramic crowns: preliminary 1-year results of a prospective clinical study. Int J Period Restor Dent 2004;24:446-455 \u003c/li\u003e\n\u003cli\u003eTortopidis D, Lyons MF, Baxendale RH, et al: The variability of bite force measurement between sessions, in different positions within the dental arch. J Oral Rehabil 1998;25:681-686 \u003c/li\u003e\n\u003cli\u003eBakke M, Michler L, Moller E: Occlusal control of mandibular elevator muscles. Scan J Dent Res 1992;100:284-291 \u003c/li\u003e\n\u003cli\u003eSichi LG, Pierre FZ, Arcila LV, de Andrade GS, Tribst JP, Ausiello P, Di Lauro AE, Borges AL. Effect of biologically oriented preparation technique on the stress concentration of endodontically treated upper central incisor restored with zirconia crown: 3d-fea. Molecules. 2021 Oct 10;26(20):6113.\u003c/li\u003e\n\u003cli\u003eValenti M, Valenti A. Retrospective survival analysis of 110 lithium disilicate crowns with feather-edge marginal preparation. International Journal of Esthetic Dentistry. 2015 Jun 1;10(2).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eMATERIAL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003eELASTIC MODULUS(Mpa)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003ePoisson\u0026rsquo;s ratio\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eEnamel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e84.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eDentine\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003ePeriodontal ligament\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.069\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eCortical bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e13.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eCancellous bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e1.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eLithium disilicate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eMonolithic zirconia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eGutta percha\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e0.69 \u0026times; 10\u003csup\u003e-3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eResin cement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e6.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 33.222%;\"\u003e\n \u003cp\u003eBulk-fill composite\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 33.8898%;\"\u003e\n \u003cp\u003e13.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 32.8881%;\"\u003e\n \u003cp\u003e0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eTable 2\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"638\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 75.0784%;\"\u003e\n \u003cp\u003eGroup I (Knife edge margins) (Von Mises stress (Mpa))\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eLiDi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003eZirconia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003ep value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCrown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e56.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e50.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.007*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.054\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.449\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eDentine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e6.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e6.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.013*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003ePDL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCortical Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e10.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e9.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.002*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCancellous Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.323\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eGP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.635\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eTable 3\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"638\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 75.0784%;\"\u003e\n \u003cp\u003eGroup II (shoulder margin) (Von Mises stress (Mpa))\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eLiDi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003eZirconia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003ep value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCrown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e60.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e53.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.156\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.495\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eDentine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e6.094\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e5.481\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.014*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003ePDL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.019\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.018\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.373\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCortical Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e11.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e10.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCancellous Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.156\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eGP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.148\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.861\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eTable 4\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"638\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 75.0784%;\"\u003e\n \u003cp\u003eLiDi\u0026nbsp; \u0026nbsp; \u0026nbsp;(Von Mises stress (Mpa))\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eGroup I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003eGroup II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003ep value\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCrown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e56.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e60.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.095\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.606\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eDentine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e6.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e6.094\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.334\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003ePDL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.019\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.605\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCortical Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e10.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e11.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.032*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCancellous Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.336\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eGP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.155\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.764\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eTable 5\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"638\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 75.0784%;\"\u003e\n \u003cp\u003eZirconia (Von Mises stress (Mpa))\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eGroup I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003eGroup II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003ep value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCrown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e50.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e53.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.266\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.054\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.597\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eDentine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e6.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e5.481\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.346\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003ePDL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.018\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.705\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCortical Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e9.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e10.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.025*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eCancellous Bone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003eGP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.9216%;\"\u003e\n \u003cp\u003e0.115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.148\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 25.0784%;\"\u003e\n \u003cp\u003e0.696\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"endocrown, lithium disilicate, zirconia, endodontically treated teeth, knife edge margins, shoulder margins","lastPublishedDoi":"10.21203/rs.3.rs-5278185/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5278185/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e- The purpose of this simulation study was to evaluate effect of different restorative design on stress concentration endocrown of different restorative materials using a finite element analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: A 3D FEA model of mandibular molar was constructed using the average values and was used in this analysis. 2 materials were used which were lithium disilicate and zirconia and 2 different margin design of knife edge and shoulder margins were used in various combinations of material and margin design. A constant 12° of internal wall angulation was considered for all the 4 models and a uniform cement thicknes of 100µm was considered. A uniform 2mm of bulk fill composite was used as a base beneath the endocrowns. 300 N load was applied on the cusps for each model and linear static analysis was carried out\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: Endocrowns of lithium disilicate was found to exert a greater stress concentration in comparison to zirconia endocrowns in both the margin designs of knife edge and shoulder. Knife edge margins were seen to yield greater stress concentration on the remaining tooth structure in comparison to shoulder margins in endocrowns of both the materials used.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e: There is a positive influence of margin design selection within the same material used for the fabrication of endocrown. However the values found in the study may not lead to clinical/ catastrophic failure of the endocrown restorations.\u003c/p\u003e","manuscriptTitle":"Effect of Different Restorative Design on Stress Concentration of Lithium Disilicate and Monolithic Zirconia Endocrown- a Finite Element Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-29 03:58:29","doi":"10.21203/rs.3.rs-5278185/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-11-21T11:41:42+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-27T03:59:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"251977777477395595449269596853954383714","date":"2024-10-27T03:48:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"50924475933564852773334595646907868582","date":"2024-10-24T00:14:51+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-23T12:59:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"94527606986372986508988164204777053568","date":"2024-10-23T12:41:57+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-10-23T10:37:53+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-10-18T05:29:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-10-17T05:16:14+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-10-17T05:14:08+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2024-10-16T19:44:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"cb38fd60-05c5-484a-9182-62289b06c1a2","owner":[],"postedDate":"October 29th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-02-10T16:00:46+00:00","versionOfRecord":{"articleIdentity":"rs-5278185","link":"https://doi.org/10.1186/s12903-024-05358-4","journal":{"identity":"bmc-oral-health","isVorOnly":false,"title":"BMC Oral Health"},"publishedOn":"2025-02-08 15:57:16","publishedOnDateReadable":"February 8th, 2025"},"versionCreatedAt":"2024-10-29 03:58:29","video":"","vorDoi":"10.1186/s12903-024-05358-4","vorDoiUrl":"https://doi.org/10.1186/s12903-024-05358-4","workflowStages":[]},"version":"v1","identity":"rs-5278185","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5278185","identity":"rs-5278185","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}