Comparator Choice in Studies Testing Endodontic Instrument Fatigue Resistance: A Network Analysis

Area of Science:

• Endodontics
• Materials Science
• Biomedical Engineering

Background:

• Cyclic fatigue resistance (CFR) is a critical property for endodontic instruments.
• Comparator selection in CFR studies is not well understood and may influence findings.
• Evolution of instrument comparisons over time needs systematic evaluation.

Purpose of the Study:

• To evaluate the network of cyclic fatigue resistance (CFR) studies in endodontics.
• To identify factors driving the choice of comparator instruments in CFR research.
• To hypothesize that indications and instrument properties influence comparator selection.

Main Methods:

• Systematic review of Medline and Embase databases (1986-2017).
• Inclusion of in vitro studies comparing cyclic fatigue resistance of at least two engine-driven endodontic instruments.
• Classification of instruments by name, alloy, and manufacturer; analysis using social network analysis.

Main Results:

• Eighty-five studies involving 56 instruments, 9 alloys, and 17 manufacturers were analyzed.
• A clustered network with three subnetworks (glide path, shaping, retreatment) was identified.
• ProTaper Universal and Mtwo instruments emerged as central 'hub' nodes; conventional Nickel-Titanium was the dominant alloy.

Conclusions:

• Instrument comparisons in CFR studies are primarily driven by clinical indications.
• Dominance of certain instruments and conventional Nickel-Titanium alloy suggests potential bias.
• Evidence robustness varies; less-tested instruments may have less reliable data; further research into network geometry factors is warranted.