Needle Gauge Influences Pain Perception During Intrapulpal Anaesthesia - A Randomized Clinical Trial

OBJECTIVE: The purpose of this randomized trial was to assess the pain perception during intrapulpal anesthesia (IP) using thinner gauge needles and syringes with or without topical anaesthesia as an adjunct. METHODS: One hundred patients, on whom the inferior alveolar nerve block and intraligamentary injections failed, were recruited for the trial. Block randomization was performed and the patients were allocated into 4 groups based on the needle gauge and topical application of anaesthesia prior to IP injection. In two groups (27GN, 31GN) the patients received IP injection with 27 gauge or 31 gauge needles. The patients of other two groups received topical lignocaine-prilocaine mixture prior to the IP injection with 27 or 31 gauge needles, respectively (27GT, 31GT). The visual analogue scale (VAS) was used to assess the pain immediately after IP injection and after cleaning and shaping by a blinded outcome assessor. The Kruskal-Wallis test for overall comparisons followed by the post-hoc analysis using the Conover’s test (P<0.05) was done. Chi-square and Fischer exact test was used to assess the proportion of patients who were comfortable during IP anaesthesia. RESULTS: The intensity of pain during IP administration with 31GN and 31GT (3.7 and 2.3 respectively) was significantly less in comparison to 27GN and 27GT (5.6 and 5.7 respectively). The proportion of patients who were significantly comfortable with IP injections in the groups 31GN and 31GT (52% and 80% respectively) were more (VAS<4) when compared to 27GN and 27GT (12% and 8% respectively). Topical application of lignocaine-prilocaine reduced the pain on IP injection significantly when used as an adjunct with 31 gauge needles. The anaesthetic success of IP anaesthesia was comparable and 100% (VAS scoring <4) in all the groups. CONCLUSION: Thinner gauge needles (31 gauge) significantly reduce pain perceived during IP anaesthesia. Topical anaesthesia with lignocaine-prilocaine acts as an effective adjunct only with 31gauge needle.