CONSORT Randomized Clinical Trial| Volume 47, ISSUE 9, P1345-1351, September 2021

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Effect of Apical Third Enlargement to Different Preparation Sizes and Tapers on Postoperative Pain and Outcome of Primary Endodontic Treatment: A Prospective Randomized Clinical Trial



      The purpose of this study was to evaluate the effect of apical preparation size and taper on postoperative pain and healing after primary endodontic treatment.


      One hundred and twenty patients with asymptomatic mandibular first molars with radiographic evidence of periapical pathology and with a periapical index (PAI) score ≥3 were randomly assigned to 2 groups, group 1 and 2, based on apical enlargement to 2 and 3 sizes larger than the initial apical binding file (IABF), respectively. Each group was further divided into subgroups A and B depending on the apical enlargement taper of 4% and 6%, respectively. Endodontic treatment was performed, and the final apical enlargement in all the groups was performed as follows: group 1A, 2 sizes larger than the IABF with a 4% taper; group 1B, 2 sizes larger than the IABF with a 6% taper; group 2A, 3 sizes larger than the IABF with a 4% taper; and group 2B, 3 sizes larger than the IABF with a 6% taper. Postoperative pain was assessed at 6, 12, 24, 48, and 72 hours. Clinical evaluation and the change in the PAI score on radiographs were assessed at the 3-, 6-, and 12-month follow-ups.


      No significant difference in postoperative pain was found. The success rate was lowest (57.1%) in group 1 subgroup A as evidenced by the significant change in the PAI score between group 1 subgroup A and the rest of the groups at the 6- and 12-month follow-ups.


      Apical preparation to 2 sizes larger than the IABF with a 4% taper is insufficient and results in significantly lower success rates compared with larger preparation sizes and tapers.

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        • Ramachandran Nair P.N.
        Light and electron microscopic studies of root canal flora and periapical lesions.
        J Endod. 1987; 13: 29-39
        • Sjogren U.
        • Hagglund B.
        • Sundqvist G.
        • Wing K.
        Factors affecting the long-term results of endodontic treatment.
        J Endod. 1990; 16: 498-504
        • Simon J.H.
        The apex: how critical is it?.
        Gen Dent. 1994; 42: 330-334
        • Card S.J.
        • Sigurdsson A.
        • Orstavik D.
        • Trope M.
        The effectiveness of increased apical enlargement in reducing intracanal bacteria.
        J Endod. 2002; 28: 779-783
        • Baugh D.
        • Wallace J.
        The role of apical instrumentation in root canal treatment: a review of the literature.
        J Endod. 2005; 31: 333-340
        • Weiger R.
        • Bartha T.
        • Kalwitzki M.
        • Löst C.
        A clinical method to determine the optimal apical preparation size. Part I.
        Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006; 102: 686-691
        • Coldero L.G.
        • McHugh S.
        • MacKenzie D.
        • Saunders W.P.
        Reduction in intracanal bacteria during root canal preparation with and without apical enlargement.
        Int Endod J. 2002; 35: 437-446
        • Butcher S.
        • Mansour A.
        • Ibrahim M.
        Influence of apical preparation size on effective conventional irrigation in the apical third: a scanning electron microscopic study.
        Eur Endod J. 2019; 4: 9-14
        • Fornari V.J.
        • Silva-Sousa Y.T.
        • Vanni J.R.
        • et al.
        Histological evaluation of the effectiveness of increased apical enlargement for cleaning the apical third of curved canals.
        Int Endod J. 2010; 43: 988-994
        • Saini H.R.
        • Tewari S.
        • Sangwan P.
        • et al.
        Effect of different apical preparation sizes on outcome of primary endodontic treatment: a randomized controlled trial.
        J Endod. 2012; 38: 1309-1315
        • Souza R.A.
        • Dantas J.C.
        • Brandão P.M.
        • et al.
        Apical third enlargement of the root canal and its relationship with the repair of periapical lesions.
        Eur J Dent. 2012; 6: 385-388
        • Saini H.R.
        • Sangwan P.
        • Sangwan A.
        Pain following foraminal enlargement in mandibular molars with necrosis and apical periodontitis: a randomized controlled trial.
        Int Endod J. 2016; 49: 1116-1123
        • Silva E.J.
        • Menaged K.
        • Ajuz N.
        • et al.
        Postoperative pain after foraminal enlargement in anterior teeth with necrosis and apical periodontitis: a prospective and randomized clinical trial.
        J Endod. 2013; 39: 173-176
        • Orstavik D.
        • Kerekes K.
        • Molven O.
        Effects of extensive apical reaming and calcium hydroxide dressing on bacterial infection during treatment of apical periodontitis: a pilot study.
        Int Endod J. 1991; 24: 1-7
        • Buchanan L.S.
        The standardized-taper root canal preparation--part 1. Concepts for variably tapered shaping instruments.
        Int Endod J. 2000; 33: 516-529
        • Siqueira Jr., J.F.
        Microbial causes of endodontic flare-ups.
        Int Endod J. 2003; 36: 453-463
        • Yaylali I.E.
        • Teke A.
        • Tunca Y.M.
        The effect of foraminal enlargement of necrotic teeth with a continuous rotary system on postoperative pain: a randomized controlled trial.
        J Endod. 2017; 43: 359-363
        • Wu M.K.
        • Barkis D.
        • Roris A.
        • Wesselink P.R.
        Does the first file to bind correspond to the diameter of the canal in the apical region?.
        Int Endod J. 2002; 35: 264-267
        • Orstavik D.
        • Kerekes K.
        • Eriksen H.M.
        The periapical index: a scoring system for radiographic assessment of apical periodontitis.
        Endod Dent Traumatol. 1986; 2: 20-34
        • Pak J.G.
        • White S.N.
        Pain prevalence and severity before, during, and after root canal treatment: a systematic review.
        J Endod. 2011; 37: 429-438
        • Sjögren U.
        • Figdor D.
        • Persson S.
        • Sundqvist G.
        Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis.
        Int Endod J. 1997; 30: 297-306
        • Gotler M.
        • Bar-Gil B.
        • Ashkenazi M.
        Postoperative pain after root canal treatment: a prospective cohort study.
        Int J Dent. 2012; 2012: 310467
        • Wang N.
        • Knight K.
        • Dao T.
        • Friedman S.
        Treatment outcome in endodontics-The Toronto Study. Phases I and II: apical surgery.
        J Endod. 2004; 30: 751-761
        • Mickel A.K.
        • Chogle S.
        • Liddle J.
        • et al.
        The role of apical size determination and enlargement in the reduction of intracanal bacteria.
        J Endod. 2007; 33: 21-23
        • 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: 417-420
        • Silvestrin T.
        • Torabinejad M.
        • Handysides R.
        • Shabahang S.
        Effect of apex size on the leakage of gutta-percha and sealer-filled root canals.
        Quintessence Int. 2016; 47: 373-378
        • Marinho A.C.
        • Martinho F.C.
        • Zaia A.A.
        • et al.
        Influence of the apical enlargement size on the endotoxin level reduction of dental root canals.
        J Appl Oral Sci. 2012; 20: 661-666
        • Rollison S.
        • Barnett F.
        • Stevens R.H.
        Efficacy of bacterial removal from instrumented root canals in vitro related to instrumentation technique and size.
        Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002; 94: 366-371
        • Brunson M.
        • Heilborn C.
        • Johnson D.J.
        • Cohenca N.
        Effect of apical preparation size and preparation taper on irrigant volume delivered by using negative pressure irrigation system.
        J Endod. 2010; 36: 721-724
        • Vera J.
        • Siqueira Jr., J.F.
        • Ricucci D.
        • et al.
        One- versus two-visit endodontic treatment of teeth with apical periodontitis: a histobacteriologic study.
        J Endod. 2012; 38: 1040-1052
        • Boutsioukis C.
        • Gogos C.
        • Verhaagen B.
        • et al.
        The effect of apical preparation size on irrigant flow in root canals evaluated using an unsteady computational fluid dynamics model.
        Int Endod J. 2010; 43: 874-881
        • Ng Y.L.
        • 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: 583-609
        • Plotino G.
        • Nagendrababu V.
        • Bukiet F.
        • 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: 707-729