Effect of Conservative Access Cavity Preparation on the Fracture Resistance of Endodontically Treated Molars
Abstract
Introduction: This study aimed to evaluate the influence of different access cavity designs (conservative versus traditional) and the impact of thermocycling and load cycling on the fracture resistance of endodontically treated molars. Materials and Methods: In this in vitro investigation, sixty extracted human molars were selected and allocated into six groups based on access cavity design and subsequent thermocycling (1000 cycles between 5 °C and 55 °C) and load cycling (200,000 axial cycles at 80 N) protocols. Root canal treatment was performed on all specimens using standardized endodontic procedures. Fracture resistance was subsequently assessed using a universal testing machine. Results: The mean fracture resistance of the teeth with conservative access cavity preparation was significantly higher than that of traditional preparation (P = 0.044). Furthermore, the application of thermocycling and load cycling significantly reduced fracture resistance across all tested groups (P < 0.05). Conclusion: These findings underscore the critical roles of access cavity design and simulated functional aging conditions in determining the long-term structural durability of endodontically treated teeth. Keywords: Root canal therapy; Fracture resistance; Load cycling; Thermocycling; Access cavity Preparation.
1. Plotino G, Grande NM, Isufi A, Ioppolo P, Pedullà E, Bedini R, et al. Fracture Strength of Endodontically Treated Teeth with Different Access Cavity Designs. Journal of Endodontics. 2017 Jun;43(6):995–1000.
2. Patil P, Newase P, Pawar S, Gosai H, Shah D, Parhad SM. Comparison of Fracture Resistance of Endodontically Treated Teeth With Traditional Endodontic Access Cavity, Conservative Endodontic Access Cavity, Truss Endodontic Access Cavity, and Ninja Endodontic Access Cavity Designs: An In Vitro Study. Cureus. 2022 Aug 17;
3. Vorster M, van der Vyver PJ, Markou G. Traditional and Conservative Molar Endodontic Access Cavity Designs: A Classification and Overview. South African Dental Journal. 2022 Nov 2;77(07):407–12.
4. Sedgley CM, Messer HH. Are endodontically treated teeth more brittle? Journal of Endodontics. 1992 Jul;18(7):332–5.
5. Makade CS, Meshram GK, Warhadpande M, Patil PG. A comparative evaluation of fracture resistance of endodontically treated teeth restored with different post core systems - an in-vitro study. The Journal of Advanced Prosthodontics. 2011;3(2):90.
6. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. Journal of Endodontics. 1989 Nov;15(11):512–6.
7. Tang W, Wu Y, Smales RJ. Identifying and Reducing Risks for Potential Fractures in Endodontically Treated Teeth. Journal of Endodontics. 2010 Apr;36(4):609–17.
8. Osman Msc IA, Ahmed HA, Osman IA. Scholars Journal of Dental Sciences (SJDS) The Effect of Access Cavity Design on Fracture Resistance of Endodontically Treated First Molars: In Vitro Study. 2018;
9. Clark D, Khademi JA. Case Studies in Modern Molar Endodontic Access and Directed Dentin Conservation. Dental Clinics of North America. 2010 Apr;54(2):275–89.
10. al Amri MD, Al‐Johany S, Sherfudhin H, al Shammari B, al Mohefer S, al Saloum M, et al. Fracture resistance of endodontically treated mandibular first molars with conservative access cavity and different restorative techniques: An in vitro study. Australian Endodontic Journal. 2016 Dec 16;42(3):124–31.
11. Chlup Z, Žižka R, Kania J, Přibyl M. Fracture behaviour of teeth with conventional and mini-invasive access cavity designs. Journal of the European Ceramic Society. 2017 Nov;37(14):4423–9.
12. Silva EJNL, Rover G, Belladonna FG, De-Deus G, da Silveira Teixeira C, da Silva Fidalgo TK. Impact of contracted endodontic cavities on fracture resistance of endodontically treated teeth: a systematic review of in vitro studies. Clinical Oral Investigations. 2018 Jan 3;22(1):109–18.
13. Clark D, Khademi J, Herbranson E. Fracture resistant endodontic and restorative preparations. dent today. 2013;
14. Saberi EA, Pirhaji A, Zabetiyan F. Effects of endodontic access cavity design and thermocycling on fracture strength of endodontically treated teeth. Clinical, Cosmetic and Investigational Dentistry. 2020;12:149–56.
15. Gluskin AH, Peters CI, Peters OA. Minimally invasive endodontics: challenging traditional concepts for preserving tooth structure. J Endod. 2022;48(5):389-397.
16. Plotino G, Grande NM, Testarelli L, Gambarini G. Influence of minimally invasive endodontic cavities on root canal shaping ability. J Dent. 2018;74:63-70.
17. Kishen A, Asundi A, Tan K. Stress distribution in endodontically treated teeth: effect of post and core materials. J Endod.2017;43(9):1487-1493.
18. Clark D, Khademi J. Modern endodontic access and dentin conservation. Clin Oral Investig. 2016;20(5):957-965.
19. Saeed M, Al-Obadi M, Salim A, Alsawaf AY, Hadi K. Impact of access cavity design on fracture resistance of endodontically treated molars: A systematic review. Vol. 13, Clinical, Cosmetic and Investigational Dentistry. Dove Medical Press Ltd; 2021. p. 1–10.
20. Yuan K, Niu C, Xie Q, Jiang W, Gao L, Huang Z, et al. Comparative evaluation of the impact of minimally invasive preparation vs. conventional straight-line preparation on tooth biomechanics: a finite element analysis. European Journal of Oral Sciences. 2016 Dec;124(6):591–6.
21. Sabeti M, Kazem M, Dianat O, Bahrololumi N, Beglou A, Rahimipour K, et al. Impact of Access Cavity Design and Root Canal Taper on Fracture Resistance of Endodontically Treated Teeth: An Ex Vivo Investigation. Journal of Endodontics. 2018 Sep;44(9):1402–6.
22. Özel Bektas Ö, Eren D, Herguner Siso S, Akin GE. Effect of thermocycling on the bond strength of composite resin to bur and laser treated composite resin. Lasers in medical science. 2012 Jul;27(4):723–8.
23. Morresi AL, Trubiani O, D'Amario M, Caputi S. Thermal and mechanical loading effects on fracture resistance of endodontically treated teeth. Int Endod J. 2021;54(3):245-253.
24. Van Meerbeek B, Yoshihara K, Yoshida Y. Adhesion to enamel and dentin: current status and future challenges. Dent Mater. 2020;36(6):779-786.
25. Bassir SH, Labibzadeh A, Mollaverdi F. Effect of thermomechanical fatigue on fracture resistance of restored teeth. Int J Dent. 2015;2015:1-9.
2. Patil P, Newase P, Pawar S, Gosai H, Shah D, Parhad SM. Comparison of Fracture Resistance of Endodontically Treated Teeth With Traditional Endodontic Access Cavity, Conservative Endodontic Access Cavity, Truss Endodontic Access Cavity, and Ninja Endodontic Access Cavity Designs: An In Vitro Study. Cureus. 2022 Aug 17;
3. Vorster M, van der Vyver PJ, Markou G. Traditional and Conservative Molar Endodontic Access Cavity Designs: A Classification and Overview. South African Dental Journal. 2022 Nov 2;77(07):407–12.
4. Sedgley CM, Messer HH. Are endodontically treated teeth more brittle? Journal of Endodontics. 1992 Jul;18(7):332–5.
5. Makade CS, Meshram GK, Warhadpande M, Patil PG. A comparative evaluation of fracture resistance of endodontically treated teeth restored with different post core systems - an in-vitro study. The Journal of Advanced Prosthodontics. 2011;3(2):90.
6. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. Journal of Endodontics. 1989 Nov;15(11):512–6.
7. Tang W, Wu Y, Smales RJ. Identifying and Reducing Risks for Potential Fractures in Endodontically Treated Teeth. Journal of Endodontics. 2010 Apr;36(4):609–17.
8. Osman Msc IA, Ahmed HA, Osman IA. Scholars Journal of Dental Sciences (SJDS) The Effect of Access Cavity Design on Fracture Resistance of Endodontically Treated First Molars: In Vitro Study. 2018;
9. Clark D, Khademi JA. Case Studies in Modern Molar Endodontic Access and Directed Dentin Conservation. Dental Clinics of North America. 2010 Apr;54(2):275–89.
10. al Amri MD, Al‐Johany S, Sherfudhin H, al Shammari B, al Mohefer S, al Saloum M, et al. Fracture resistance of endodontically treated mandibular first molars with conservative access cavity and different restorative techniques: An in vitro study. Australian Endodontic Journal. 2016 Dec 16;42(3):124–31.
11. Chlup Z, Žižka R, Kania J, Přibyl M. Fracture behaviour of teeth with conventional and mini-invasive access cavity designs. Journal of the European Ceramic Society. 2017 Nov;37(14):4423–9.
12. Silva EJNL, Rover G, Belladonna FG, De-Deus G, da Silveira Teixeira C, da Silva Fidalgo TK. Impact of contracted endodontic cavities on fracture resistance of endodontically treated teeth: a systematic review of in vitro studies. Clinical Oral Investigations. 2018 Jan 3;22(1):109–18.
13. Clark D, Khademi J, Herbranson E. Fracture resistant endodontic and restorative preparations. dent today. 2013;
14. Saberi EA, Pirhaji A, Zabetiyan F. Effects of endodontic access cavity design and thermocycling on fracture strength of endodontically treated teeth. Clinical, Cosmetic and Investigational Dentistry. 2020;12:149–56.
15. Gluskin AH, Peters CI, Peters OA. Minimally invasive endodontics: challenging traditional concepts for preserving tooth structure. J Endod. 2022;48(5):389-397.
16. Plotino G, Grande NM, Testarelli L, Gambarini G. Influence of minimally invasive endodontic cavities on root canal shaping ability. J Dent. 2018;74:63-70.
17. Kishen A, Asundi A, Tan K. Stress distribution in endodontically treated teeth: effect of post and core materials. J Endod.2017;43(9):1487-1493.
18. Clark D, Khademi J. Modern endodontic access and dentin conservation. Clin Oral Investig. 2016;20(5):957-965.
19. Saeed M, Al-Obadi M, Salim A, Alsawaf AY, Hadi K. Impact of access cavity design on fracture resistance of endodontically treated molars: A systematic review. Vol. 13, Clinical, Cosmetic and Investigational Dentistry. Dove Medical Press Ltd; 2021. p. 1–10.
20. Yuan K, Niu C, Xie Q, Jiang W, Gao L, Huang Z, et al. Comparative evaluation of the impact of minimally invasive preparation vs. conventional straight-line preparation on tooth biomechanics: a finite element analysis. European Journal of Oral Sciences. 2016 Dec;124(6):591–6.
21. Sabeti M, Kazem M, Dianat O, Bahrololumi N, Beglou A, Rahimipour K, et al. Impact of Access Cavity Design and Root Canal Taper on Fracture Resistance of Endodontically Treated Teeth: An Ex Vivo Investigation. Journal of Endodontics. 2018 Sep;44(9):1402–6.
22. Özel Bektas Ö, Eren D, Herguner Siso S, Akin GE. Effect of thermocycling on the bond strength of composite resin to bur and laser treated composite resin. Lasers in medical science. 2012 Jul;27(4):723–8.
23. Morresi AL, Trubiani O, D'Amario M, Caputi S. Thermal and mechanical loading effects on fracture resistance of endodontically treated teeth. Int Endod J. 2021;54(3):245-253.
24. Van Meerbeek B, Yoshihara K, Yoshida Y. Adhesion to enamel and dentin: current status and future challenges. Dent Mater. 2020;36(6):779-786.
25. Bassir SH, Labibzadeh A, Mollaverdi F. Effect of thermomechanical fatigue on fracture resistance of restored teeth. Int J Dent. 2015;2015:1-9.
| Files | ||
| Issue | Vol 13, No 3 (Summer 2026) | |
| Section | Original Article(s) | |
| Keywords | ||
| Root canal therapy; Fracture resistance; Load cycling; Thermocycling; Access cavity Preparation. | ||
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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. |
How to Cite
1.
Kazemi H, Khazaei AR, Khazaei AH, Rashki Ghaleh No F. Effect of Conservative Access Cavity Preparation on the Fracture Resistance of Endodontically Treated Molars. J Craniomaxillofac Res. 2026;13(3):338-344.
