Impact of Contracted Endodontic Access Cavity on Shaping Ability of Hyflex Electrical Discharge Machining Single File Using Cone Beam Computed Tomography: An Ex Vivo Study


  • Ahmed Bayoumi Department of Conservative Dentistry, Faculty of Dentistry, Alexandria University, Alexandria, Egypt
  • Magdy Mohamed Aly Department of Endodontics, Faculty of Dentistry, Minia University, Minya, Egypt; Department of Endodontics, Faculty of Dentistry, Egyptian Russian University, Badr City, Egypt
  • Reham Hassan Department of Endodontics, Faculty of Dentistry, Minia University, Minya, Egypt; Department of Endodontics, Faculty of Dentistry, Egyptian Russian University, Badr City, Egypt



HyFlex electrical discharge machining, Cone-beam computed tomography, Traditional access, Contracted access, Canal transportation, Centering ability, Control memory, Nickel-titanium instruments


AIM: The aim of the study was to evaluate and compare the effect of different access cavity designs, using cone-beam computed tomography (CBCT), on root canal transportation, and centralization performed on two rooted maxillary premolars.

METHODS: Twenty maxillary premolars were randomly divided into two groups. In Group 1, traditional endodontic cavities (TECs) were prepared. In Group 2, contracted endodontic cavities (CECs) were prepared. Mechanical preparation was done by HyFlex electrical discharge machining (EDM) single file in both groups. CBCT imaging was performed pre- and post-root canal preparation for calculations of root canal transportation and centering ability.

RESULTS: Data were analyzed using Mann–Whitney U test and Kruskal–Wallis test. For transportation, teeth with CECs showed the statistically significantly highest median amount of transportation, while as for centering ability, results showed no significant difference between both groups.

CONCLUSION: Under the conditions of this study, HyFlex EDM prepared canals with different access cavity designs without significant shaping errors. TEC showed less transportation than CEC, while both TEC and CEC had no effect on the file centering ability.


Download data is not yet available.


Metrics Loading ...

Plum Analytics Artifact Widget Block


Silva EJ, Rover G, Belladonna FG, de-Deus G, Teixeira CS, Fidalgo TK. Impact of contracted endodontic cavities on fracture resistance of endodontically treated teeth: A systematic review of in vitro studies. Clin Oral Investig. 2018;22(1):109-18. PMid:29101548

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. Eur J Oral Sci. 2016;124(6):591-6. PMid:27704709

Lin C, Lin D, He W. Impacts of 3 different endodontic access cavity designs on dentin removal and point of entry in 3-dimensional digital models. J Endod. 2020;46(4):524-30. PMid:32115250

Hassan R, Roshdy N, Issa N. Comparison of canal transportation and centering ability of Xp Shaper, WaveOne and Oneshape: A cone beam computed tomography study of curved root canals. Acta Odontol Latinoam. 2018;31(1):67-74. PMid:30056469

Hargreaves K, Cohen S. Cohen’s Pathways of the Pulp. 10th ed. Amsterdam: Mosby; 2010.

Elnaghy AM, Elsaka SE. Evaluation of root canal transportation, centering ratio, and remaining dentin thickness associated with ProTaper next instruments with and without glide path. J Endod. 2014;40(12):2053-6. PMid:25301350

Capar ID, Ertas H, Ok E, Arslan H, Ertas ET. Comparative study of different novel nickel-titanium rotary systems for root canal preparation in severely curved root canals. J Endod. 2014;40(6):852-6. PMid:24862716

da Frota MF, Filho IB, Berbert FL. Cleaning capacity promoted by motor driven or manual instrumentation using ProTaper Universal system: Histological analysis. J Conserv Dent. 2013;16(1):79-82. PMid:23349583

Lammertyn PA. Furcation groove of maxillary first premolar, thickness and dentin structures. J Endod. 2009;35(6):814-7. PMid:19482177

Kishen A. Mechanisms and risk factors for fracture predilection in endodontically treated teeth. Endod Top. 2006;13:57-83.

Elnaghy AM, Elsaka SE. Shaping ability of ProTaper gold and ProTaper universal files by using cone-beam computed tomography. Indian J Dent Res. 2016;27(1):37-41. PMid:27054859

Krishan R, Paqué F, Ossareh A, Kishen A, Dao T, Friedman S, et al. Impacts of conservative endodontic cavity on root canal instrumentation efficacy and resistance to fracture assessed in incisors, premolars, and molars. J Endod. 2014;40(8):1160-6. PMid:25069925

Eaton JA, Clement DJ, Lloyd A, Marchesan MA. Microcomputed tomographic evaluation of the influence of root canal system landmarks on access outline forms and canal curvatures in mandibular molars. J Endod. 2015;41(11):1888-91. PMid:26433857

Schneider SW. A comparison of canal preparations in straight and curved root canals. Oral Surg Oral Med Oral Pathol. 1971;32(2):271-5. PMid:5284110

Fayyad DM, Sabet NE, El-Said Mahmoud EH. Computed tomographic evaluation of the apical shaping ability of hero shaper and Revo-S. Quintessence Int. 2012;6(2):119-24.

Patel S, Rhodes J. A practical guide to endodontic access cavity preparation in molar teeth. Br Dent J. 2007;203(3):133-40. PMid:17694021

Goerig AC, Michelich RJ, Schultz HH. Instrumentation of root canals in molar using the step-down technique. J Endod. 1982;8(12):550-4. PMid:6962274

Clark D, Khademi J. Modern molar endodontic access and directed dentin conservation. Dent Clin North Am. 2010;54(2):249-73. PMid:20433977

Moore B, Verdelis K, Kishen A, Dao T, Friedman S. Impacts of contracted endodontic cavities on instrumentation efficacy and biomechanical responses in maxillary molars. J Endod. 2016;42(12):1779-83. PMid:27871481

Gambill JM, Alder M, del Rio CE. Comparison of nickeltitanium and stainless steel hand-file instrumentation using computed tomography. J Endod. 1996;22(7):369-75. PMid:8935064

Cicchetti DV. Guidelines, criteria, and rules of thumb for evaluating normed and standardized assessment instruments in psychology. Psychol Assess. 1994;6(4):284-90.

Plotino G, Grande NM, Isufi A, Ioppolo P, Pedulla E, Bedini R, et al. Fracture strength of endodontically treated teeth with different access cavity designs. J Endod. 2017;43(6):995-1000. PMid:28416305

Gutmann JL. Minimally invasive dentistry (Endodontics). J Conserv Dent. 2013;16(4):282-3. PMid:23956526

Gutmann JL. The dentin-root complex: Anatomic and biologic consideration in restoring endodontically treated teeth. J Prosthet Dent. 1992;67(4):458-66. PMid:1507126

Rhodes JS, Pitt Ford TR, Lynch JA, Liepins PJ, Curtis RV. Microcomputed tomography: A new tool for experimental endodontology. Int Endod J. 1999;32(3):165-70. PMid:10530203

Gluskin AH, Brown DC, Buchanan LS. A reconstructed computerized tomographic comparison of NiTi rotary GT files versus traditional instruments in canals shaped by novice operators. Int Endod J. 2001;34(6):476-84. PMid:11556516

Uyanik M, Cehreli Z, Mocan B, Dagli F. Comparative evaluation of three nickel-titanium instrumentation systems in human teeth using computed tomography. J Endod. 2006;32(7):668-71. PMid:16793477

Saber S, Abu El Sadat S. Effect of altering the reciprocation range on the fatigue life and the shaping ability of WaveOne nickel-titanium instruments. J Endod. 2013;39(5):685-8. PMid:23611391

Pawar AM, Thakur B, Metzger Z, Kfir A, Pawar M. The efficacy of the self-adjusting file versus WaveOne in removal of root filling residue that remains in oval canals after the use of ProTaper retreatment files: A cone-beam computed tomography study. J Conserv Dent. 2016;19(1):72-6. PMid:26957798

Swain MV, Xue J. State of the art of micro-CT applications in dental research. Int J Oral Sci. 2009;1(4):177-88. PMid:20690421

Bürklein S, Donnermeyer D, Hentschel TJ, Schäfer E. Shaping ability and debris extrusion of new rotary nickel-titanium root canal instruments. Materials. 2021;14(5):1063. PMid:33668333

Arıcan-Öztürk B, AtavAteş A, Fişekçioğlu E. Cone-beam computed tomographic analysis of shaping ability of XP-endo shaper and ProTaper next in large root canals. J Endod. 2020;46(3):437-43. PMid:31911004

Domark JD, Hatton JF, Benison RP, Hildebolt FC. An ex vivo comparison of digital radiography and cone beam and micro computed tomography in the detection of the number of canals in the mesiobuccal roots of maxillary molars. J Endod. 2013;39(7):7901-5. PMid:23791260

Peters OA. Current challenges and concepts in the preparation of root canal systems: A review. J Endod. 2004;30(8):559-67. PMid:15273636

Alovisi M, Pasqualini D, Musso E, Bobbio E, Giuliano C, Mancino D, et al. Influence of contracted endodontic access on root canal geometry: An in vitro study. J Endod. 2018;44(4):614-20. PMid:29336881

Rover G, Belladonna FG, Bortoluzzi EA, de-Deus G, Silva EJ, Teixeira CS. Influence of access cavity design on root canal detection, instrumentation efficacy, and fracture resistance assessed in maxillary molars. J Endod. 2017;43(10):1657-62. PMid:28739013

Ozyurek T, Yılmaz G. Shaping ability of reciproc, WaveOne GOLD, and HyFlex EDM single-file systems in simulated s-shaped canals. J Endod. 2017;43(5):805-9. PMid:28292599

Linn J, Messer HH. Effect of restorative procedures on the strength of endodontically treated molars. J Endod. 1994;20(10):479-85. PMid:7714419

Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: Part 1: Periapical health. Int Endod J. 2011;44(7):583-609. PMid:21366626

Ng YL, Mann V, Gulabivala K. Tooth survival following non-surgical root canal treatment: A systematic review of the literature. Int Endod J. 2010;43(3):171-89. PMid:20158529

Caplan DJ, Cai J, Yin G, White BA. Root canal filled versus non-root canal filled teeth: A retrospective comparison of survival times. J Public Health Dent. 2005;65(2):90-6. PMid:15929546




How to Cite

Bayoumi A, Magdy Mohamed Aly, Hassan R. Impact of Contracted Endodontic Access Cavity on Shaping Ability of Hyflex Electrical Discharge Machining Single File Using Cone Beam Computed Tomography: An Ex Vivo Study. Open Access Maced J Med Sci [Internet]. 2021 Oct. 10 [cited 2021 Dec. 4];9(D):221-8. Available from:



Dental Pathology and Endodontics