Dental Anaesthesia Needles: An EDS Study

OBJECTIVE: To assess and compare the chemical composition, microstructure and compositional homogeneity in the alloy used by different manufacturers to make dental anaesthesia needles. METHODS: Needles were randomly selected from those manufactured by each of seven different manufacturers. Each needle was sectioned in transverse and longitudinal planes and examined by elemental x-ray microanalysis and x-ray mapping using a Leo Supra 50 VP Field Emission SEM, and a Quantax QX2 EDS system with an x-flash dry detector of 127 ev resolution, to determine the chemical composition, microstructure and compositional homogeneity of the needles. The test samples were ranked in terms of their known tendency to fracture (Behbehani, 2005). RESULTS: Aluminium and Niobium were present in the alloy from which the needles least likely to break had been manufactured, but not in the alloy from which the most brittle needles were made. The concentrations of Chromium and Nickel was higher in the better quality needles. CONCLUSION: Compositions of each sample did not generally conform to international manufacturing standards, and varied between the manufacturers, who appear to apply their own standards. Further research is needed to determine a uniform standard for dental anaesthesia needles.