Dentine chips produced by nickel-titanium rotary instruments

Area of Science:

• Endodontics
• Dental Materials Science
• Biomaterials Engineering

Background:

• Nickel-titanium rotary instruments are widely used in endodontic procedures.
• Understanding instrument design and its effect on debris production is crucial for clinical success.
• Previous research has not fully elucidated the relationship between instrument cross-sectional shape and dentine chip characteristics.

Purpose of the Study:

• To compare the cross-sectional geometry of ProFile and Quantec nickel-titanium rotary files.
• To analyze the characteristics of dentine chips produced by these instruments.
• To investigate potential correlations between instrument shape and chip morphology.

Main Methods:

• Transverse sectioning of ProFile and Quantec files (ISO 25, 0.06 taper) at different levels from the tip.
• Scanning electron microscopy (SEM) for examining cross-sectional shape and cutting angles.
• Computerized particle analysis of dentine chips generated during instrumentation.

Main Results:

• All instruments exhibited negative cutting angles, varying with cross-sectional level.
• ProFile and Quantec files showed good internal consistency in shape, with exceptions noted for Quantec at 4mm.
• Quantec files produced significantly larger and rounder dentine chips compared to ProFile files (P < 0.05).
• ProFile and stainless steel engine reamer chips were similar in size (P > 0.05).

Conclusions:

• Significant differences exist in dentine chip characteristics produced by ProFile and Quantec nickel-titanium rotary files.
• Instrument cross-sectional geometry influences the size and shape of cutting debris.
• No direct, simple relationship was found between the specific file geometries examined and the resulting dentine chips.