Related Experiment Video
Updated: Oct 10, 2025

Author Spotlight: Enhancing Microinjection Needle Quality by Wet Beveling
Published on: September 27, 2024
Needle tip deformation in local dental anesthesia - A technical note
Amely Hartmann1, Tina Lawall2, Luhrenberg Philipp1
1Department of Oral and Maxillofacial Surgery, University Medical Centre of the Johannes Gutenberg University of Mainz, Augustusplatz 2, 55131, Mainz, Germany.
Introduction:
The aim of this in vitro study was to investigate the mechanical deformation rate of dental cannula tips after injection simulation in a new developed animal model.
Materials And Methods:
A new mechanical device was designed to define forces (100 g for 60 s) to impact a pigs jaw bone with different cannulas (25-Gauge/27-Gauge) from dental local anaesthesia syringes. 8 different products (100 cannulas each) were evaluated. Cannula tips were examined for deformation under the digital microscope VHX-100 (500-fold magnification).
Results:
27G and 27G free flow showed a significantly lower likelihood of bending (OR 0.05; p = 0.0001). Comparing 27G cannulas of the same outer diameter but different inner diameter, large inner diameter produced a significantly higher deformation rate than those of cannulas with a standard inner diameter. 12-38% of the cannulas showed manufacturing defects and production-related deformation.
Conclusions:
Cannula deformation seems to depend on the inner diameter, bevel and cutting profile. Multiple use of the same cannula could result in more pronounced deformation, increasing the risk of complications during local anesthesia.
Related Concept Videos
Local Anesthetics: Adverse Effects
Once absorbed into the systemic circulation, local anesthetics can affect the organs that depend on the functioning of sodium...
Local Anesthetics: Differential Sensitivity of Nerve Fibers
Local Anesthetics: Clinical Application as Epidural Anesthesia
Since epidural anesthetics can be infused through an epidural catheter, all types of drugs, including short-acting ones, can be administered. Chloroprocaine and lidocaine are examples of short and long-duration anesthetics, respectively. Bupivacaine...
Local Anesthetics: Clinical Application as Surface, Infiltration, and Conduction Block Anesthesia

