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Breakage of ultrasonic root-end preparation tips
A D Walmsley1, P J Lumley, W T Johnson
1Department of Endodontics, University of Iowa, Iowa City, USA.
Journal of Endodontics
|June 1, 1996
Summary
Modified ultrasonic tips used in endodontic surgery can fracture, especially those with significant bending. This study found that tips with 70-degree curvatures or greater broke under load, highlighting a risk during root-end cavity preparation.
Area of Science:
- Endodontics
- Dental Materials Science
- Biomaterials Engineering
Background:
- Modified ultrasonic tips are crucial for preparing root-end cavities in endodontic surgery.
- Understanding the mechanical integrity of these specialized instruments is essential for clinical safety and efficacy.
Purpose of the Study:
- To investigate the susceptibility of modified ultrasonic tips to fracture during simulated clinical use.
- To identify factors influencing ultrasonic tip breakage during root-end cavity preparation.
Main Methods:
- Ten distinct ultrasonic tip designs were tested using an ultrasonic unit at maximum power.
- Tips were subjected to increasing loads (100 g increments every 5 min) for 15 minutes on prepared root-end cavities.
- Fracture points and characteristics were analyzed, including scanning electron microscopy (SEM) of fractured surfaces.
Main Results:
- Ultrasonic tips with curvatures of 70 degrees or greater fractured within the initial 5-minute loading period.
- Fractures consistently occurred 2-3 mm from the tip, specifically at a bend in the instrument.
- SEM analysis indicated brittle fractures with minimal deformation of the remaining tip material.
Conclusions:
- The degree of curvature is a significant factor contributing to the fracture of modified ultrasonic tips.
- Certain tip designs, particularly those with pronounced bends, pose a higher risk of breakage during endodontic procedures.
- Clinical protocols should consider the design limitations of ultrasonic tips to prevent intraoperative complications.