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Impacts of Contracted Endodontic Cavities on Instrumentation Efficacy and Biomechanical Responses in Maxillary Molars

      Highlights

      • This study evaluated CECs and TECs with respect to instrumentation efficacy, axial strain response at the mesiobuccal and palatal root surfaces, and load at failure under static compressive loading applied after cyclic loading.
      • Instrumentation efficacy was not significantly impacted by endodontic cavity design.
      • Axial root strain under cyclic loading varied without consistent patterns for CECs or TECs.
      • Load at failure for contracted endodontic cavities (CECs) did not differ significantly from traditional endodontic cavities (TECs) and was lower for both groups compared with intact molars controls.

      Abstract

      Introduction

      Recently, we reported that in mandibular molars contracted endodontic cavities (CECs) improved fracture strength compared with traditional endodontic cavities (TECs) but compromised instrumentation efficacy in distal canals. This study assessed the impacts of CECs on instrumentation efficacy and axial strain responses in maxillary molars.

      Methods

      Eighteen extracted intact maxillary molars were imaged with micro–computed tomographic imaging (12-μm voxel), assigned to CEC or TEC groups (n = 9/group), and accessed accordingly. Canals were instrumented (V-Taper2H; SSWhite Dental, Lakewood, NJ) with 2.5% sodium hypochlorite irrigation, reimaged, and the proportion of the modified canal wall determined. Cavities were restored with bonded composite resin (TPH-Spectra-LV; Dentsply International, York, PA). Another 28 similar molars (n = 14/group) with linear strain gauges (Showa Measuring Instruments, Tokyo, Japan) attached to mesiobuccal and palatal roots were subjected to load cycles (50–150 N) in the Instron Universal Testing machine (Instron, Canton, MA), and the axial microstrain was recorded before access and after restoration. These 28 molars and additional 11 intact molars (control) were cyclically fatigued (1 million cycles, 5–50 N, 15 Hz) and subsequently loaded to failure. Data were analyzed by the Wilcoxon rank sum and Kruskal-Wallis tests (α = 0.05).

      Results

      The overall mean proportion of the modified canal wall did not differ significantly between CECs (49.7% ± 12.0%) and TECs (44.7% ± 9.0%). Relative changes in axial microstrain responses to load varied in both groups. The mean load at failure for CECs (1703 ± 558 N) did not differ significantly from TECs (1384 ± 377 N) and was significantly lower (P < .005) for both groups compared with intact molars (2457 ± 941 N).

      Conclusions

      In maxillary molars tested in vitro, CECs did not impact instrumentation efficacy and biomechanical responses compared with TECs.

      Key Words

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      References

        • de Chevigny C.
        • Dao T.T.
        • Basrani B.R.
        • et al.
        Treatment outcome in endodontics: the Toronto study-phase 4: initial treatment.
        J Endod. 2008; 34: 258-263
        • Landys Borén D.
        • Jonasson P.
        • Kvist T.
        Long-term survival of endodontically treated teeth at a public dental specialist clinic.
        J Endod. 2015; 41: 176-181
        • Fransson H.
        • Dawson V.S.
        • Frisk F.
        • et al.
        Survival of root-filled teeth in the Swedish adult population.
        J Endod. 2016; 42: 216-220
        • Tang W.
        • Wu Y.
        • Smales R.J.
        Identifying and reducing risks for potential fractures in endodontically treated teeth.
        J Endod. 2010; 36: 609-617
        • Goerig A.C.
        • Michelich R.J.
        • Schultz H.H.
        Instrumentation of root canals in molar using the step-down technique.
        J Endod. 1982; 8: 550-554
        • Schroeder K.P.
        • Walton R.E.
        • Rivera E.M.
        Straight line access and coronal flaring: effect on canal length.
        J Endod. 2002; 28: 474-476
        • Clark D.
        • Khademi J.
        Modern molar endodontic access and directed dentin conservation.
        Dent Clin North Am. 2010; 54: 249-273
        • Bóveda C.
        • Kishen A.
        Contracted endodontic cavities: the foundation for less invasive alternatives in the management of apical periodontitis.
        Endod Topics. 2015; 33: 169-186
        • Panitvisai P.
        • Messer H.
        Cuspal deflection in molars in relation to endodontic and restorative procedures.
        J Endod. 1995; 21: 57-61
        • Jantarat J.
        • Panitvisai P.
        • Palamara J.E.
        • Messer H.H.
        Comparison of methods for measuring cuspal deformation in teeth.
        J Dent. 2001; 29: 75-82
        • Reeh E.S.
        • Messer H.H.
        • Douglas W.H.
        Reduction in tooth stiffness as a result of endodontic and restorative procedures.
        J Endod. 1989; 15: 512-516
        • Soares P.V.
        • Santos-Filho P.C.F.
        • Gomide H.A.
        • et al.
        Influence of restorative technique on the biomechanical behavior of endodontically treated maxillary premolars. Part II: strain measurement and stress distribution.
        J Prosthet Dent. 2008; 99: 114-122
        • Pereira J.
        • McDonald A.
        • Petrie A.
        • Knowles J.
        Effect of cavity design on tooth surface strain.
        J Prosthet Dent. 2013; 110: 369-375
        • Lang H.
        • Korkmaz Y.
        • Schneider K.
        • Raab W.H.-M.
        Impact of endodontic treatments on the rigidity of the root.
        J Dent Res. 2006; 85: 364-368
        • Hofmann N.
        • Just N.
        • Hugo B.
        • Haller B.
        The effect of glass ionomer cement or composite resin bases on restoration of cuspal stiffness of endodontically treated premolars in vitro.
        Clin Oral Investig. 1998; 2: 77-83
        • Moezizadeh M.
        • Mokhtari N.
        Fracture resistance of endodontically treated premolars with fibre-reinforced composite restorations.
        J Conserv Dent. 2011; 14: 277-281
        • Hamouda I.M.
        • Shehata S.H.
        Fracture resistance of posterior teeth restored with modern restorative materials.
        J Biomed Res. 2011; 25: 418-424
        • Plotino G.
        • Buono L.
        • Grande N.M.
        • et al.
        Fracture resistance of endodontically treated molars restored with extensive composite resin restorations.
        J Prosthet Dent. 2008; 99: 225-232
        • Murdoch-Kinch C.A.
        • McLean M.E.
        Minimally invasive dentistry.
        J Am Dent Assoc. 2003; 134: 87-95
        • Krishan R.
        • Paqué F.
        • Ossareh A.
        • 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: 1160-1166
        • Watts D.
        • El Mowafy O.
        • Grant A.
        Fracture resistance of lower molars with class 1 composite and amalgam restorations.
        Dent Mater. 1987; 3: 261-264
        • Peters O.
        • Laib A.
        • Göhring T.
        • Barbakow F.
        Changes in root canal geometry after preparation assessed by high-resolution computed tomography.
        J Endod. 2001; 27: 1-6
        • Peters O.
        • Peters C.
        • Schönenberger K.
        • et al.
        ProTaper rotary root canal preparation: effects of canal anatomy on final shape analysed by micro CT.
        Int Endod J. 2003; 36: 86-92
        • Paqué F.
        • Ganahl D.
        • Peters O.
        Effects of root canal preparation on apical geometry assessed by micro-computed tomography.
        J Endod. 2009; 35: 1056-1059
        • DeLong R.
        • Sakaguchi R.L.
        • Douglas W.H.
        • Pintado M.R.
        The wear of dental amalgam in an artificial mouth: a clinical correlation.
        Dent Mater. 1985; 1: 238-242
        • De Boever J.A.
        • McCall Jr., W.D.
        • Holden S.
        • Ash Jr., M.M.
        Functional occlusal forces: An investigation by telemetry.
        J Prosthet Dent. 1978; 40: 326-333
        • Shen Y.
        • Zhou H.
        • Zheng Y.
        • et al.
        Metallurgical characterization of controlled memory wire nickel-titanium rotary instruments.
        J Endod. 2011; 37: 1566-1571
        • Kishen A.
        Mechanisms and risk factors for fracture predilection in endodontically treated teeth.
        Endod Topics. 2006; 17: 57-83
        • Haapasalo M.
        • Endal U.
        • Zandi H.
        • Coil J.M.
        Eradication of endodontic infection by instrumentation and irrigation solutions.
        Endod Topics. 2005; 10: 77-102
        • Meredith N.
        • Setchell D.J.
        In vitro measurement of cuspal strain and displacement in composite restored teeth.
        J Dent. 1997; 25: 331-337
        • Morin D.L.
        • Cross M.
        • Voller V.R.
        • et al.
        Biophysical stress analysis of restored teeth: modelling and analysis.
        Dent Mater. 1988; 4: 77-84
        • Linn J.
        • Messer H.H.
        Effect of restorative procedures on the strength of endodontically treated molars.
        J Endod. 2010; 20: 479-485
        • Zadik Y.
        • Sandler V.
        • Bechor R.
        • Salehrabi R.
        Analysis of factors related to extraction of endodontically treated teeth.
        Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008; 106: 31-35
        • Rodrigues F.B.
        • Paranhos M.P.G.
        • Spohr A.M.
        • et al.
        Fracture resistance of root filled molar teeth restored with glass fibre bundles.
        Int Endod J. 2010; 43: 356-362
        • Görduysus M.
        • Görduysus M.
        • Friedman S.
        Operating microscope improves negotiation of second mesiobuccal canals in maxillary molars.
        J Endod. 2001; 27: 683-686