Objectives: The aim of this study was to examine the subjective pain perception by injection and the anesthetic effect on the time course of the pain perception threshold level of the dental pulp through a needle-free injector system for local anesthesia (INJEXTM). INJEXTM provides a reduced dosage of anaesthetic solution.
Methods: Studies were carried out on the upper middle incisors of 10 young healthy volunteers after the injection of 0,6 ml anesthetic solution of articaine (4%) with vasoconstrictor (epinephrine 1:200.000). Constant current electrical tooth pulp stimulation was used (0 – 200µA) to determine pain perception threshold level. Threshold level above 200 µA was regarded as complete anesthesia. Results were recorded every two minutes. As a control anaesthesia using 0.6 ml dosage of the same solution was carried out under randomized conditions on the same group of volunteers with a conventional system (needle and syringe). Delay between both experiments was one week. The time course of local anesthesia was statistically analyzed using paired T-test.
Results: We found that the increase in pain perception threshold level after injection is slightly faster for the INJEXTM than for the conventional procedure. For every time point there was no statistical difference between experimental and control group. Although the anesthetic effect of both systems did not show any difference, the subjective pain perception by INJEXTM was slightly higher than by the conventional system. Neither effect was statistically significant.
Conclusion: The use of INJEXTM as a needle-free injection system for local anesthesia in dentistry can be recommended.