Properties of hand-held spreaders after simulated use

Area of Science:

• Endodontics
• Dental Materials Science
• Biomaterials Engineering

Background:

• Root canal spreaders are critical endodontic instruments with varying dimensions.
• Existing standards (ANSI/ADA Specification no. 71) do not fully replicate clinical usage conditions for spreader testing.
• Understanding instrument behavior under simulated clinical stress is vital for ensuring endodontic treatment success and instrument longevity.

Purpose of the Study:

• To assess the permanent deformation of D11T root canal spreaders from different manufacturers.
• To evaluate the impact of simulated clinical usage (insertion cycles) and autoclaving on spreader integrity.
• To compare the performance of Endeco, Hu-Friedy, and Premier spreaders under various stress conditions.

Main Methods:

• Measured diameters (D3, D16) and taper of 40 D11T spreaders from three companies.
• Subjected spreaders to four conditions: control, autoclaving (10 cycles), simulated insertion (50 times, 200 mm/min into 30-degree curved blocks), and combined autoclaving/insertion.
• Quantified permanent angular deformation of the instrument tip using a bend test apparatus.

Main Results:

• All tested root canal spreaders successfully passed the bend test criteria under all experimental conditions.
• Endeco (EN) spreaders exhibited a higher susceptibility to permanent deformation compared to Hu-Friedy (HF) and Premier (PR) spreaders.
• No statistically significant differences in deformation were observed between the control group and the simulated clinical usage groups (B, C, D).

Conclusions:

• While all evaluated root canal spreaders meet proposed bend test specifications, material differences influence deformation resistance.
• Endeco spreaders may be less resilient to repeated stress and sterilization compared to competitors.
• Current testing protocols may not fully capture the long-term clinical performance and potential failure modes of root canal spreaders.