J Dent Anesth Pain Med.  2023 Oct;23(5):281-285. 10.17245/jdapm.2023.23.5.281.

Bending 30-gauge needles using a needle guide: fatigue life evaluation

• Tuttle JJ
• Davidson AD
• Tuttle GK

• KMID: 2546892
• DOI: http://doi.org/10.17245/jdapm.2023.23.5.281

Abstract

Background
Dentists bend needles prior to certain injections; however, there are concerns regarding needle fracture, lumen occlusion, and sharps handling. A previous study found that a 30-gauge needle fractures after four to nine 90° bends. This fatigue life study evaluated how many 90° bends a 30-gauge dental needle will sustain before fracture when bent using a needle guide.
Methods
Two operators at Element Materials Technology, an independent testing, inspection, and certification company tested 48 30-gauge needles. After applying the needle guide, the operators bent the needle to a 90° angle and expressed the anesthetic from the tip. The needle was then bent back to a 0° angle, and the functionality was tested again. This process was repeated until the anesthetic failed to pass through the end of the needle due to fracture or obstruction. Each operator tested 24 needles (12 needles from each lot), and the number of sustained bends before the needle fracture was recorded.
Results
The average number of sustained bends before needle failure was 40.33 (95% confidence interval = 37.41–43.26), with a minimum of 20, median of 40, and a maximum of 54. In each trial, the lumen remained patent until the needle fractured. The difference between the operators was statistically significant (P < 0.001). No significant differences in performance between needle lots were observed (P = 0.504).
Conclusion
Our results suggest that using a needle guide increases the number of sustained bends before needle fracture (P < 0.000001) than those reported in previous studies. Future studies should further evaluate the use of needle guides with other needle types across a variety of operators. Furthermore, additional opportunities lie in exploring workplace safety considerations and clinical applications of anesthetic delivery using a bent needle.

Keyword

Dental Anesthesia; Needle Bending; Needle Fracture; Needle Guide; Needlestick Injury