Effects of cooling lignocaine hydrochloride for inferior alveolar nerve block - a randomised controlled trial

Aim: The purpose of this trial was to assess the clinical effects of cooling 2% lignocaine hydrochloride (with and without epinephrine) when used for inferior alveolar nerve block (IANB). Materials and methods: The trial was planned to have a 2 × 2 factorial design. One hundred patients were recruited and divided randomly into four groups of 25 each. Group I - lignocaine hydrochloride with epinephrine (room temperature); group II - lignocaine hydrochloride without epinephrine (room temperature); group III - lignocaine hydrochloride with epinephrine (refrigerated), and group IV - lignocaine hydrochloride without epinephrine (refrigerated). Electric pulp stimulations were used to assess the pulpal anaesthesia and the Heft-Parker visual analogue scale was used to assess the discomfort experienced during injection. The primary outcomes assessed were onset of action and duration of action. The secondary outcome assessed was pain on injection. The intervention assigned to each group was concealed from the patients, the senior endodontist and the principal investigator to maintain the blind trial. Statistical analysis was performed using the Kruskal-Wallis and Mann-Whitney U tests. Results: The results showed that pain at the injection site was least for group III followed by group IV. While comparing the onset of action, it was fastest for group III and slowest for group II. The longest duration of action was found in group III. Conclusion: Cooling of lignocaine hydrochloride (with and without epinephrine) resulted in lesser pain on injection, faster onset and longer duration of action in comparison with lignocaine hydrochloride (with and without epinephrine) at room temperature. Keywords: cool local anaesthetic, inferior alveolar nerve block, lignocaine hydrochloride, pulpal anaesthesia, randomised controlled trial