Buffered local anaesthetic and injection pain and onset time

Data sourcesMedline, Embase, Scopus and Scielo were searched until April 2017 supplemented by manual searching.Study selectionClinical trials with parallel-groups, crossover and split mouth in patients older than 18 years were included with no language restrictions. The primary outcome considered was changes in pain intensity, while the secondary outcome was changes on onset time.Data extraction and synthesisTwo authors extracted data using a standard data form. Inter-rater reliability was calculated as high. For the primary outcome all scales were converted to a 0-100 scale. For the secondary outcome all measures were normalised in minutes. Risk of bias was assessed using the Cochrane Collaboration tool. The treatment effect was calculated using mean differences and 95% confidence interval. Heterogeneity and sensitivity analysis were performed. Data were combined using a random effect model.ResultsFourteen studies were included in the review. Of those nine were included in a meta-analysis for the primary outcome pain showing no significant reduction: -7.38 (-15.67-0.91) for normal tissue (five studies) and -4.41 (-15.25-6.43) for inflamed tissue on four studies. No statistically significant results were found in the block (three studies) or the infiltration groups (seven studies). Four studies were included in a meta-analysis for onset time. Significant reduction was achieved for inferior alveolar nerve blocks: -1.26 (-1.41 to -1.10) on three studies and when used on inflamed tissue: -1.37 (-2.03 to -0.70) from one study. High degree of heterogeneity was observed in all groups.ConclusionsThe authors concluded that buffered lidocaine does not reduce pain from injection and the onset time reduction in inferior alveolar nerve blocks and in inflamed tissues while the magnitude of the reduction is not clinically relevant.