ABSTRACT  

Root canal shaping is a fundamental component of chemomechanical preparation that contributes to reducing the microbial load and creates a canal geometry suitable for irrigation and root canal obturation. This narrative review aimed to explain the biological, mechanical, and technical principles of root canal shaping; evaluate its development from manual instrumentation to contemporary engine-driven nickel-titanium systems; compare different kinematic and instrumentation strategies; and discuss the principal clinical stages of shaping in light of current evidence. English-language studies indexed in PubMed/MEDLINE were searched without a lower publication date restriction. The reference lists of relevant narrative reviews, systematic reviews, clinical practice guidelines, and original studies were also examined. Advances in nickel-titanium alloys, heat-treatment technologies, and instrument design have enabled the development of different shaping systems employing continuous rotation, reciprocation, and adaptive motion. However, current evidence does not demonstrate that a specific kinematic approach or instrument system is superior under all clinical conditions. A safe shaping protocol requires the maintenance of canal patency, creation of a reproducible glide path, accurate determination of the working length, and selection of an apical size and taper appropriate for the individual case. Although larger preparations may increase instrument-wall contact and irrigant delivery, they should be evaluated in relation to additional dentin loss and procedural risks. Consequently, instrument selection and preparation dimensions should be determined on a case-specific basis by considering the balance among root canal anatomy, biological debridement requirements, and dentin preservation.
 

KEYWORDS 

Endodontics; root canal preparation; nickel-titanium; continuous rotation; reciprocation; glide path; apical enlargement.

REFERENCES

1) Schilder H. Cleaning and shaping the root canal. Dent Clin North Am. 1974;18(2):269–296. PubMed
2) Hülsmann M, Peters OA, Dummer PMH. Mechanical preparation of root canals: shaping goals, techniques and means. Endod Topics. 2005;10(1):30–76. doi:10.1111/j.1601-1546.2005.00152.x
3) Tomson PL, Adams N, Kavanagh D, Virdee SS. Non-surgical endodontics: contemporary biomechanical preparation of the root canal system. Br Dent J. 2025;238(7):478–486. doi:10.1038/s41415-025-8599-1
4) Peters OA, Schönenberger K, Laib A. Effects of four Ni-Ti preparation techniques on root canal geometry assessed by micro computed tomography. Int Endod J. 2001;34(3):221–230. doi:10.1046/j.1365-2591.2001.00373.x
5) Walia HM, Brantley WA, Gerstein H. An initial investigation of the bending and torsional properties of Nitinol root canal files. J Endod. 1988;14(7):346–351. doi:10.1016/S0099-2399(88)80196-1
6) Gavini G, Santos MD, Caldeira CL, Machado MEL, Freire LG, Iglecias EF, et al. Nickel-titanium instruments in endodontics: a concise review of the state of the art. Braz Oral Res. 2018;32(Suppl 1):e67. doi:10.1590/1807-3107bor-2018.vol32.0067
7) Arias A, Peters OA. Present status and future directions: canal shaping. Int Endod J. 2022;55(Suppl 3):637–655. doi:10.1111/iej.13698
8) Duncan HF, Kirkevang LL, Peters OA, El-Karim I, Krastl G, Del Fabbro M, et al. Treatment of pulpal and apical disease: the European Society of Endodontology (ESE) S3-level clinical practice guideline. Int Endod J. 2023;56(Suppl 3):238–295. doi:10.1111/iej.13974
9) Baethge C, Goldbeck-Wood S, Mertens S. SANRA—a scale for the quality assessment of narrative review articles. Res Integr Peer Rev. 2019;4:5. doi:10.1186/s41073-019-0064-8
10) Green BN, Johnson CD, Adams A. Writing narrative literature reviews for peer-reviewed journals: secrets of the trade. J Chiropr Med. 2006;5(3):101–117. doi:10.1016/S0899-3467(07)60142-6
11) Aminoshariae A, Kulild J. Master apical file size—smaller or larger: a systematic review of microbial reduction. Int Endod J. 2015;48(11):1007–1022. doi:10.1111/iej.12410
12) Siqueira JF Jr, Magalhães KM, Rôças IN. Bacterial reduction in infected root canals treated with 2.5% NaOCl as an irrigant and calcium hydroxide/camphorated paramonochlorophenol paste as an intracanal dressing. J Endod. 2007;33(6):667–672. doi:10.1016/j.joen.2007.01.004
13) Rodrigues RCV, Zandi H, Kristoffersen AK, Enersen M, Mdala I, Ørstavik D, et al. Influence of the apical preparation size and the irrigant type on bacterial reduction in root canal-treated teeth with apical periodontitis. J Endod. 2017;43(7):1058–1063. doi:10.1016/j.joen.2017.02.004
14) Aminoshariae A, Kulild JC. Master apical file size—smaller or larger: a systematic review of healing outcomes. Int Endod J. 2015;48(7):639–647. doi:10.1111/iej.12370
15) Pérez AR, Alves FRF, Marceliano-Alves MF, Provenzano JC, Gonçalves LS, Neves AA, et al. Effects of increased apical enlargement on the amount of unprepared areas and coronal dentine removal: a micro-computed tomography study. Int Endod J. 2018;51(6):684–690. doi:10.1111/iej.12873
16) Nagendrababu V, Ahmed HMA. Shaping properties and outcomes of nickel-titanium rotary and reciprocation systems using micro-computed tomography: a systematic review. Quintessence Int. 2019;50(3):186–195. doi:10.3290/j.qi.a41977
17) Călin C, Focșăneanu AM, Paulsen F, Didilescu AC, Niță T. Shaping efficiency of rotary and reciprocating kinematics of engine-driven nickel-titanium instruments in moderate and severely curved root canals using microcomputed tomography: a systematic review of ex vivo studies. J Endod. 2024;50(7):907–924. doi:10.1016/j.joen.2024.03.009
18) Puleio F, Lo Giudice G, Militi A, Bellezza U, Lo Giudice R. Does low-taper root canal shaping decrease the risk of root fracture? A systematic review. Dent J (Basel). 2022;10(6):94. doi:10.3390/dj10060094
19) Plotino G, Nagendrababu V, Bukiet F, Grande NM, Veettil SK, De-Deus G, et al. Influence of negotiation, glide path, and preflaring procedures on root canal shaping—terminology, basic concepts, and a systematic review. J Endod. 2020;46(6):707–729. doi:10.1016/j.joen.2020.01.023
20) Martins JNR, Marques D, Mata A, Caramês J. Clinical efficacy of electronic apex locators: systematic review. J Endod. 2014;40(6):759–777. doi:10.1016/j.joen.2014.03.011.
21) Patiño PV, Biedma BM, Liébana CR, Cantatore G, Bahillo JG. The influence of a manual glide path on the separation rate of NiTi rotary instruments. J Endod. 2005;31(2):114–116. doi:10.1097/01.DON.0000136209.28647.13
22) Weine FS. The use of non-ISO-tapered instruments for canal flaring. Compend Contin Educ Dent. 1996;17(7):651–656, 658–660, 662–663; quiz 664.
23) Gambill JM, Alder M, del Rio CE. Comparison of nickel-titanium and stainless steel hand-file instrumentation using computed tomography. J Endod. 1996;22(7):369–375. doi:10.1016/S0099-2399(96)80221-4
24) Gluskin AH, Brown DC, Buchanan LS. A reconstructed computerized tomographic comparison of Ni-Ti rotary GT files versus traditional instruments in canals shaped by novice operators. Int Endod J. 2001;34(6):476–484. doi:10.1046/j.1365-2591.2001.00422.x
25) Del Fabbro M, Afrashtehfar KI, Corbella S, El-Kabbaney A, Perondi I, Taschieri S. In vivo and in vitro effectiveness of rotary nickel-titanium vs manual stainless steel instruments for root canal therapy: systematic review and meta-analysis. J Evid Based Dent Pract. 2018;18(1):59–69. doi:10.1016/j.jebdp.2017.08.001
26) Thompson SA. An overview of nickel-titanium alloys used in dentistry. Int Endod J. 2000;33(4):297–310. doi:10.1046/j.1365-2591.2000.00339.x
27) Liang Y, Yue L. Evolution and development: engine-driven endodontic rotary nickel-titanium instruments. Int J Oral Sci. 2022;14(1):12. doi:10.1038/s41368-021-00154-0
28) Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod. 2006;32(11):1031–1043. doi:10.1016/j.joen.2006.06.008
29) Zupanc J, Vahdat-Pajouh N, Schäfer E. New thermomechanically treated NiTi alloys—a review. Int Endod J. 2018;51(10):1088–1103. doi:10.1111/iej.12924
30) Yahata Y, Yoneyama T, Hayashi Y, Ebihara A, Doi H, Hanawa T, et al. Effect of heat treatment on transformation temperatures and bending properties of nickel-titanium endodontic instruments. Int Endod J. 2009;42(7):621–626. doi:10.1111/j.1365-2591.2009.01563.x
31) Shim KS, Oh S, Kum KY, Kim YC, Jee KK, Chang SW. Mechanical and metallurgical properties of various nickel-titanium rotary instruments. Biomed Res Int. 2017;2017:4528601. doi:10.1155/2017/4528601
32) Kim E, Ha JH, Dorn SO, Shen Y, Kim HC, Kwak SW. Effect of heat treatment on mechanical properties of nickel-titanium instruments. J Endod. 2024;50(2):213–219. doi:10.1016/j.joen.2023.10.018
33) Baek SH, Lee CJ, Versluis A, Kim BM, Lee W, Kim HC. Comparison of torsional stiffness of nickel-titanium rotary files with different geometric characteristics. J Endod. 2011;37(9):1283–1286. doi:10.1016/j.joen.2011.05.032
34) Versluis A, Kim HC, Lee W, Kim BM, Lee CJ. Flexural stiffness and stresses in nickel-titanium rotary files for various pitch and cross-sectional geometries. J Endod. 2012;38(10):1399–1403. doi:10.1016/j.joen.2012.06.008
35) Çapar ID, Arslan H. A review of instrumentation kinematics of engine-driven nickel-titanium instruments. Int Endod J. 2016;49(2):119–135. doi:10.1111/iej.12432
36) Ahn SY, Kim HC, Kim E. Kinematic effects of nickel-titanium instruments with reciprocating or continuous rotation motion: a systematic review of in vitro studies. J Endod. 2016;42(7):1009–1017. doi:10.1016/j.joen.2016.04.002
37) Rahbani Nobar B, Dianat O, Rahbani Nobar B, Shirvani A, Zargar N, Kazem M, et al. Effect of rotary and reciprocating instrumentation motions on postoperative pain incidence in nonsurgical endodontic treatments: a systematic review and meta-analysis. Eur Endod J. 2021;6(1):3–14. doi:10.14744/eej.2020.51523
38) Yared G. Canal preparation using only one Ni-Ti rotary instrument: preliminary observations. Int Endod J. 2008;41(4):339–344. doi:10.1111/j.1365-2591.2007.01351.x
39) Lee JY, Kwak SW, Ha JH, Kim HC. Ex-vivo comparison of torsional stress on nickel-titanium instruments activated by continuous rotation or adaptive motion. Materials (Basel). 2020;13(8):1900. doi:10.3390/ma13081900
40) Pedullà E, Corsentino G, Ambu E, Rovai F, Campedelli F, Rapisarda S, et al. Influence of continuous rotation or reciprocation of Optimum Torque Reverse motion on cyclic fatigue resistance of nickel-titanium rotary instruments. Int Endod J. 2018;51(5):522–528. doi:10.1111/iej.12769
41) Duarte PM, Silva PB, Alcalde MP, Vivan RR, Rosa RAD, Duarte MAH, et al. Canal transportation, centering ability, and cyclic fatigue promoted by Twisted File Adaptive and Navigator EVO instruments at different motions. J Endod. 2018;44(9):1425–1429. doi:10.1016/j.joen.2018.06.002
42) Yuan G, Yang G. Comparative evaluation of the shaping ability of single-file system versus multi-file system in severely curved root canals. J Dent Sci. 2018;13(1):37–42. doi:10.1016/j.jds.2017.09.005
43) Caviedes-Bucheli J, Castellanos F, Vasquez N, Ulate E, Munoz HR. The influence of two reciprocating single-file and two rotary-file systems on the apical extrusion of debris and its biological relationship with symptomatic apical periodontitis: a systematic review and meta-analysis. Int Endod J. 2016;49(3):255–270. doi:10.1111/iej.12452
44) Bartols A, Laux G, Walther W. Multiple-file vs single-file endodontics in dental practice: a study in routine care. PeerJ. 2016;4:e2765. doi:10.7717/peerj.2765
45) Barbosa AFA, Silva EJNL, Coelho BP, Ferreira CMA, Lima CO, Sassone LM. The influence of endodontic access cavity design on the efficacy of canal instrumentation, microbial reduction, root canal filling and fracture resistance in mandibular molars. Int Endod J. 2020;53(12):1666–1679. doi:10.1111/iej.13383
46) Ajina MA, Billis G, Chong BS. The effect of glide path preparation on root canal shaping procedures and outcomes. Eur Endod J. 2022;7(2):92–105. doi:10.14744/eej.2022.97659
47) Schroeder KP, Walton RE, Rivera EM. Straight line access and coronal flaring: effect on canal length. J Endod. 2002;28(6):474–476. doi:10.1097/00004770-200206000-00015
48) Pécora JD, Capelli A, Guerisoli DMZ, Spanó JCE, Estrela C. Influence of cervical preflaring on apical file size determination. Int Endod J. 2005;38(7):430–435. doi:10.1111/j.1365-2591.2005.00946.x
49) Hartmann RC, Peters OA, de Figueiredo JAP, Rossi-Fedele G. Association of manual or engine-driven glide path preparation with canal centring and apical transportation: a systematic review. Int Endod J. 2018;51(11):1239–1252. doi:10.1111/iej.12943
50) Yaylali IE, Demirci GK, Kurnaz S, Celik G, Kaya BU, Tunca YM. Does maintaining apical patency during instrumentation increase postoperative pain or flare-up rate after nonsurgical root canal treatment? A systematic review of randomized controlled trials. J Endod. 2018;44(8):1228–1236. doi:10.1016/j.joen.2018.05.002
51) Ravanshad S, Adl A, Anvar J. Effect of working length measurement by electronic apex locator or radiography on the adequacy of final working length: a randomized clinical trial. J Endod. 2010;36(11):1753–1756. doi:10.1016/j.joen.2010.08.017
52) Kaur G, Thomas AR, Samson RS, Varghese E, Ponraj RR, Nagraj SK, et al. Efficacy of electronic apex locators in comparison with intraoral radiographs in working length determination—a systematic review and meta-analysis. BMC Oral Health. 2024;24(1):532. doi:10.1186/s12903-024-04259-w
53) Wu MK, Barkis D, Roris A, Wesselink PR. Does the first file to bind correspond to the diameter of the canal in the apical region? Int Endod J. 2002;35(3):264–267. doi:10.1046/j.1365-2591.2002.00474.x
54) Khademi A, Yazdizadeh M, Feizianfard M. Determination of the minimum instrumentation size for penetration of irrigants to the apical third of root canal systems. J Endod. 2006;32(5):417–420. doi:10.1016/j.joen.2005.11.008
55) Brunson M, Heilborn C, Johnson DJ, Cohenca N. Effect of apical preparation size and preparation taper on irrigant volume delivered by using negative pressure irrigation system. J Endod. 2010;36(4):721–724. doi:10.1016/j.joen.2009.11.028
56) Fornari VJ, Silva-Sousa YTC, Vanni JR, Pécora JD, Versiani MA, Sousa-Neto MD. Histological evaluation of the effectiveness of increased apical enlargement for cleaning the apical third of curved canals. Int Endod J. 2010;43(11):988–994. doi:10.1111/j.1365-2591.2010.01724.x
57) Saini HR, Tewari S, Sangwan P, Duhan J, Gupta A. Effect of different apical preparation sizes on outcome of primary endodontic treatment: a randomized controlled trial. J Endod. 2012;38(10):1309–1315. doi:10.1016/j.joen.2012.06.024

Cite this article

Arslanparcasi, H. F. (2026). Root Canal Shaping in Endodontics: Fundamental Principles and Clinical Approaches: A Narrative Review. INTERNATIONAL JOURNAL OF HEALTH & MEDICAL RESEARCH, 5(8), 766-778. https://doi.org/10.58806/ijhmr.2026.v5i8n07