Effect of dentine cutting efficiency on the lateral force created by torque‐controlled rotary instruments

Abstract

AIM To study the impact of dentine cutting efficiency of rotary instruments on the lateral force they create when instrumenting simulated root canals in bovine dentine. METHODOLOGY Lateral cutting efficiency of austenitic files (ProTaper Universal) was compared to that of counterparts of a reported identical geometrical design with a martensite phase component (ProTaper Gold) in bovine dentine disks (n = 6). Instrument shapes were studied using digital microscopy. The intracanal lateral force exerted by the two systems in simulated premolars (n = 9) made from bovine incisor roots containing a standardized narrow root canal of 16 mm length was monitored using a testing apparatus equipped with a torque-controlled endodontic motor/handpiece. Data were compared using parametric statistics, alpha error = 0.05. RESULTS The geometrical design of the two systems under investigation was found to be identical. The martensitic nickel-titanium rotary files had a significantly (t-test, P < 0.05) higher lateral cutting efficiency than austenitic counterparts. This difference, however, did not impact the lateral force that was created when instrumenting simulated premolar root canals. Furthermore, lateral force peaks were generated with the progressively tapered instruments under investigation towards the full working length. Even though a glide path was prepared, the first instrument in the full-length sequence (S1) created the highest lateral force (anova/Tukey's HSD, P < 0.05). CONCLUSIONS The current experimental set-up allows the study of the lateral force generated during root canal instrumentation. This force was not influenced by the dentine cutting efficiency of the instruments under investigation, but rather by their geometrical design.

Radicular intracanal splitting forces and cutting efficiency of NiTi rotary versus reciprocating systems: A comparative in vitro study

“…Since the highest forces were provoked close to the working length (Tables 2 and 3), caution is advised when preparing the apical third with thin dentinal walls when large taper and wide-diameter instruments are applied. The rotary instrumentation ndings align with previous studies [27]. Another in vitro study concluded that the low fracture threshold of mandibular incisor roots during an obturation procedure was 1.5 kg or 14.7 N [11].…”

“…Sample sectioning and mounting for the testing platform. The samples were prepared according to a previously published methodology [27]. In short, the teeth were decoronated with a slow-speed round diamond disk at the cementoenamel junction (CEJ) level on the interproximal aspect, leaving approximately 2 mm of coronal tooth structure on the buccal and lingual aspects (Fig.…”

“…A custom-made splitting force measuring device was used to measure the intracanal lateral forces [27].…”

Post Placement and Restoration of Endodontically Treated Canines: A Finite Element Analysis Study

“…The geometric pattern of the endodontic instruments, the technique used, and the shape of the root canal (straight or curved) are important factors in achieving optimal treatment. As mentioned above, the root canal has three portions (coronal, middle, and apical) and, according to studies conducted on a tooth with a straight root canal, the highest stress occurs in the apical portion [ 41 , 42 ], constituting a disadvantage in the endodontic treatment of canine 3.3. There must be a close connection between the materials used for the treatment to give an optimal result.…”

Impact of Radial Lands on the Reduction of Torque/Force Generation of a Heat-Treated Nickel-Titanium Rotary Instrument

“…However, most of these studies have a major drawback, which is the inability to eliminate several confounding parameters other than a single variable of interest, resulting from the difference in multiple parameters among the brands being tested. Thus, some studies have compared instruments with the same geometry but different heat-treatment [22,24,25]. In this regard, to the best of our knowledge, no studies to date have definitively proven the impact of the radial land on the shaping performance of NiTi rotary instruments.…”