Effect of root canal treatment procedures with a novel rotary nickel titanium instrument (TRUShape) on stress in mandibular molars: a comparative finite element analysis

Abstract

The aim of this study was to investigate and compare, via finite element analysis (FEA), the effects of endodontic access and canal preparation on stress distribution under functional loading of a mandibular molar treated with novel (TRUShape) and conventional (Vortex) rotary root canal preparation instruments. Identical plastic mandibular molars with natural anatomy had all 4 canals shaped with either TRUShape or a conventional rotary, Vortex (#20 and #30, both by Dentsply Tulsa Dental). Finite element analysis was used to evaluate stress distribution in untreated and treated models. Micro-computed tomography (MCT) of the extracted teeth shaped in vitro was used to inform the FEA model regarding the geometry of root canals and external surfaces. Modeling the intact periodontal support and cancellous/cortical bone was based on anatomical data. Profiles of average and maximum von Mises stresses in dentin of the four treated conditions under functional loading were compared to the untreated model. This comparison was performed for each tooth model with and without root canal obturation and composite restoration. On average, the dentin sections with the most changes after preparation were located in the access cavity, with average stress increase up to +5.7, +8.5, +8.9, and +10.2 % for the TRUShape #20, Vortex #20, TRUShape #30 and Vortex #30, respectively, relative to the untreated model. Within the root canal system, the average stress differences were smaller than <5 % with lower values for TRUShape preparation. A reduction of the average stress in the access cavity was observed as an effect of the composite restoration, while about the same von Mises stress' profiles were found into the root canal. In this finite element analysis, preparation of the access cavity resulted in increased von Mises stresses under functional occlusal load. The limited (up to 0.7 %) retained radicular dentin in the TRUShape versus the Vortex cavity proved effective in reducing masticatory stresses. The bonded restoration modeled in this study only partially counterbalance the combined effects of access cavity and root canal preparation.

Evaluation of the Effect of Rotary Systems on Stresses in a New Testing Model Using a 3-Dimensional Printed Simulated Resin Root with an Oval-shaped Canal: A Finite Element Analysis Study

“…Furthermore, photopolymerized resin root models were used instead of real teeth to ensure standardization. Bonessio et al (31) mentioned the reliability of plastic tooth models used in their study; based on their pilot study, they reported the maximum spatial discrepancy as <1%. According to them, resulting stress errors were at least an order of magnitude less.…”

Effect of perforation size and furcal lesion on stress distribution in mandibular molars: a finite element analysis

“…, Dejak & Mlotkowski , Bonessio et al . ). In case of oblique loading, the tooth experiences bending.…”

“…, Bonessio et al . ). According to the present results, the root filled teeth had higher P max stresses compared with the intact models in accordance with previous studies (Zelic et al .…”

Stress distribution in a mandibular premolar after separated nickel-titanium instrument removal and root canal preparation: a three-dimensional finite element analysis

“…Different simulated material properties (Young’s modulus (E) and Poisson’s ratio values) were generated, based on data from the literature (Table 2). 15,17,19 Cross-sections of root canal were created from the apex at intervals of 1.0 mm. To visualize the stress distributions and magnitudes in the models, the data were transformed into color graphics.…”