Evaluation of the Shaping Ability of Three Thermally Treated Nickel–Titanium Endodontic Instruments on Standardized 3D-printed Dental Replicas Using Cone-Beam Computed Tomography

Abstract

Background and Objectives: The aim of the present study is to compare the efficacy of three root canal preparation systems in the shaping of 3D-printed root canal replicas of single rooted teeth. Materials and Methods: Sixty 3D-printed root canal replicas were produced and divided into three groups, each consisting of twenty samples. Each group was shaped with a different instrument: Reciproc Blue R25/08 (VDW GmbH, Munich, Gemany), WaveOne Gold Primary 25/07 (Dentsply Sirona, Ballaigues, Switzerland), and ProTaper Gold F2 25/08 (Denstply Sirona). To ensure the reproducibility of pre- and post-operative CBCT images of the root canals, the endodontic printed replicas were placed in a mould of silicon impression material. A cone-beam computed tomography (CBCT) software was used to compare pre- and post-instrumentation images collected at three levels of the root canal length: 3, 6, and 9 mm from the apical foramen. The amount of transportation, centring ability, and curvature angle after shaping were evaluated for each system. The results were statistically analysed and compared using one-way analysis of variance (ANOVA). Results: Regarding the transportation of the root canal after shaping, significant differences between groups at 3 mm (p = 0.010721) and 6 mm (p = 0.000046) were recorded in the mesio-distal direction, while in the bucco-lingual significant differences were only observed at 6 mm (p = 0.000554). Reciproc Blue removed more dentin from the mesial and buccal wall of the root canal. When evaluating the centring ability of the three systems, significant differences were observed between the groups at the level of 9 mm (p = 0.037258) in the mesio-distal direction, and at the level of 6 mm (p = 0.038197) in the bucco-lingual direction. Significant differences of the canal curvature angle after shaping were also observed between groups (p = 0.000001). Reciproc Blue straightened the curvature the most, while ProTaper Gold the least. Conclusions: All systems produced minor root canal transportation. No instrument was able to achieve a perfect centring preparation of the root canal. All systems produced a small degree of root canal straightening.

A Comparative Study of Two Martensitic Alloy Systems in Endodontic Files Carried out by Unskilled Hands

“…In addition, we used them because standardized conditions of root canal anatomy could be created [55]. However, it is true that the characteristics of this material differ from those of natural tooth dentin in terms of the reproduction of anatomical variations, having less hardness [56,57], and the generation of heat during instrumentation, which can soften this material [58,59].…”

Endodontic fillings evaluated using en face OCT, microCT and SEM

“…For the access cavities, preparations are made with dental rotary instruments, high-speed diamond burs and water spray. The next step was the instrumentation of the root canal with nickel-titanium (Ni-Ti) endodontic rotary instruments (System GT, Dentsply Tulsa Dental, Tulsa, Oklahoma, USA) following the standard protocol [31] (Figure 1, a and b). (ii) Each canal is firstly irrigated with 5% Sodium Hypochlorite, followed by alternative irrigation with 5% Sodium Hypochlorite and 17% Ethylenediaminetetraacetic acid (EDTA) for a total time of 30 minutes.…”

“…For the access cavities, preparations are made with dental rotary instruments, high-speed diamond burs and water spray. The next step was the instrumentation of the root canal with nickel–titanium (Ni–Ti) endodontic rotary instruments (System GT, Dentsply Tulsa Dental, Tulsa, Oklahoma, USA) following the standard protocol [ 31 ] (Figure 1 , a and b).…”

3D-Printed Teeth in Endodontics: Why, How, Problems and Future—A Narrative Review

“…Another study investigated the effect of storage conditions on tooth resistance to fracture, and it was found that teeth stored in water have a higher resistance to fracture than teeth stored dry [43], so the preparation of natural teeth is an unpleasant task as they must be stored in a strong-smelling liquid [44]. (4) Standardization: The difficulty of creating well-balanced groups in ex vivo studies and an equal student assessment is a consequence of the intricate anatomy of the root canal system [14,25,26,31,33,45]. As a consequence, studies might demonstrate the effect of canal anatomy rather than the variable of interest [33].…”

“…It has also been reported that it is difficult to remove the support material from parts with features with fine details [23,26,45,72]. To the author's knowledge, there is no study that demonstrates that the internal root canal anatomy is free of support material, and the majority do not explain the protocol used for removing it from inside the root canals, or even if it was performed [1,55,58,59,66,73].…”