Rajesh Krishan1, Frank Paqué2, Arezou Ossareh1, Anil Kishen1, Thuan Dao3, Shimon Friedman4. 1. Disciplines of Endodontics, University of Toronto, Toronto, Ontario, Canada. 2. Department of Endodontology, University of Zurich, Zurich, Zurich, Switzerland. 3. Disciplines of Prosthodontics, University of Toronto, Toronto, Ontario, Canada. 4. Disciplines of Endodontics, University of Toronto, Toronto, Ontario, Canada. Electronic address: s.friedman@utoronto.ca.
Abstract
INTRODUCTION: Conservative endodontic cavity (CEC) may improve fracture resistance of teeth but compromise the instrumentation of canals. This study assessed the impacts of CEC on both variables in 3 tooth types. METHODS: Extracted human intact maxillary incisors, mandibular premolars, and molars (n = 20/type) were imaged with micro-computed tomographic imaging (20-μm resolution) and assigned to CEC or traditional endodontic cavity (TEC) groups (n = 10/group/type). Minimal CECs were plotted on scanned images. Canals were prepared with WaveOne instruments (Dentsply Maillefer, Ballaigues, Switzerland) using 1.25% sodium hypochlorite and post-treatment micro-computed tomographic images obtained. The proportion of the untouched canal wall (UCW) and the dentin volume removed (DVR) for each tooth type was analyzed with the independent-samples t test. The 60 instrumented and 30 intact teeth (negative control, n = 10/type) were loaded to fracture in the Instron Universal Testing machine (Instron, Canton, MA) (1 mm/min), and the data were analyzed with 1-way analysis of variance and the Tukey test. RESULTS: The mean proportion of UCW was significantly higher (P < .04) only in the distal canals of molars with CEC (57.2% ± 21.7%) compared with TEC (36.7% ± 17.2%). The mean DVR was significantly smaller (P < .003) for CEC than for TEC in incisors (16.09 ± 4.66 vs 23.24 ± 3.38 mm(3)), premolars (8.24 ± 1.64 vs 14.59 ± 4.85 mm(3)), and molars (33.37 ± 67.71 mm(3)). The mean load at fracture for CEC was significantly higher (P < .05) than for TEC in premolars (586.8 ± 116.9 vs 328.4 ± 56.7 N) and molars (1586.9 ± 196.8 vs 641.7 ± 62.0 N). In both tooth types, CEC did not differ significantly from the negative controls. CONCLUSIONS: Although CEC was associated with the risk of compromised canal instrumentation only in the molar distal canals, it conserved coronal dentin in the 3 tooth types and conveyed a benefit of increased fracture resistance in mandibular molars and premolars.
INTRODUCTION: Conservative endodontic cavity (CEC) may improve fracture resistance of teeth but compromise the instrumentation of canals. This study assessed the impacts of CEC on both variables in 3 tooth types. METHODS: Extracted human intact maxillary incisors, mandibular premolars, and molars (n = 20/type) were imaged with micro-computed tomographic imaging (20-μm resolution) and assigned to CEC or traditional endodontic cavity (TEC) groups (n = 10/group/type). Minimal CECs were plotted on scanned images. Canals were prepared with WaveOne instruments (Dentsply Maillefer, Ballaigues, Switzerland) using 1.25% sodium hypochlorite and post-treatment micro-computed tomographic images obtained. The proportion of the untouched canal wall (UCW) and the dentin volume removed (DVR) for each tooth type was analyzed with the independent-samples t test. The 60 instrumented and 30 intact teeth (negative control, n = 10/type) were loaded to fracture in the Instron Universal Testing machine (Instron, Canton, MA) (1 mm/min), and the data were analyzed with 1-way analysis of variance and the Tukey test. RESULTS: The mean proportion of UCW was significantly higher (P < .04) only in the distal canals of molars with CEC (57.2% ± 21.7%) compared with TEC (36.7% ± 17.2%). The mean DVR was significantly smaller (P < .003) for CEC than for TEC in incisors (16.09 ± 4.66 vs 23.24 ± 3.38 mm(3)), premolars (8.24 ± 1.64 vs 14.59 ± 4.85 mm(3)), and molars (33.37 ± 67.71 mm(3)). The mean load at fracture for CEC was significantly higher (P < .05) than for TEC in premolars (586.8 ± 116.9 vs 328.4 ± 56.7 N) and molars (1586.9 ± 196.8 vs 641.7 ± 62.0 N). In both tooth types, CEC did not differ significantly from the negative controls. CONCLUSIONS: Although CEC was associated with the risk of compromised canal instrumentation only in the molar distal canals, it conserved coronal dentin in the 3 tooth types and conveyed a benefit of increased fracture resistance in mandibular molars and premolars.
Authors: Aline Batista Gonçalves Franco; Amanda Gonçalves Franco; Geraldo Alberto Pinheiro de Carvalho; Elimario Venturin Ramos; José Cláudio Faria Amorim; Alexandre Sigrist de Martim Journal: J Mater Sci Mater Med Date: 2020-04-11 Impact factor: 3.896
Authors: G Plotino; M Colangeli; T Özyürek; G DeDeus; C Panzetta; R Castagnola; N M Grande; L Marigo Journal: Clin Oral Investig Date: 2020-06-05 Impact factor: 3.573