Articaine became available as a dental local anaesthetic in the UK in 1998. Its introduction has led to two research questions being addressed. Firstly, is 4% articaine with adrenaline more effective than 2% lidocaine with adrenaline? Secondly, does the higher concentration increase the incidence of adverse effects with the former solution? It might seem simple to answer the efficacy question and a number of trials have investigated this. Similarly, a meta-analysis of the efficacy studies should provide useful information. Unfortunately it is not that easy. A major problem when investigating the efficacy of local anaesthetic solutions is a lack of a universally accepted outcome measure. Although the studies included in this meta-analysis considered anaesthetic success as an outcome measure, they did not employ a consistent definition of success. The inclusion criteria for this analysis mentions that subjects had to have non-complex dental treatment; however some of the studies incorporated were performed in volunteers having no dental treatment. Even in these volunteer studies, where anaesthesia was determined on the basis of no response to an electronic pulp tester, different definitions of success were used. One volunteer study1 defined successful anaesthesia as two consecutive non responses within 15 minutes sustained for 60 minutes. Another2 used two consecutive non responses at any time within 30 minutes as the criterion for success. So the outcome measures within the volunteer studies varied and this is compounded with the inclusion of investigations where some treatment was performed. In short the outcome measures were inconsistent within the incorporated studies. Another factor that may be of importance is the dose of local anaesthetic used. This varied between the investigations considered and unfortunately has not been accurately recorded in the summary table as the dose claimed to have been used in one of the studies3 was overestimated four-fold.

It is very important to point out that different injection techniques were compared in this analysis. This is relevant in relation to the question about adverse effects. As noted in the review4 there has been a suggestion that 4% articaine may produce more non-surgical paraesthesias compared to 2% lidocaine following mandibular block injections. So an important question to answer is “Does articaine offer any benefit in mandibular block anaesthesia?” It must be stressed that the risk of non-surgical paraesthesia is small. It is therefore important to determine if there is any advantage to the use of 4% articaine for mandibular blocks, as any increase in efficacy compared to 2% lidocaine could outweigh the low risk of paraesthesia. Unfortunately because of the multiple techniques compared in this meta-analysis such a question cannot be satisfactorily addressed. It appears that those studies included in the analysis that compared mandibular infiltration for the two drugs showed definite improvement in “success” with the former drug for the lower first molar in volunteers. It is possible that this improved efficacy of 4% articaine in the mandibular infiltration technique weighted the data to give an overall increased efficacy for this drug for the pooled data. So it is not possible to tell if 4% articaine is more effective than 2% lidocaine for mandibular blocks. So this very important question remains unanswered.

To summarise, the conclusion reported in this paper that articaine “provides a higher rate of anaesthetic success, with comparable safety to lignocaine when used as infiltration or blocks for routine dental treatments” should be interpreted with caution. Firstly, because individual block and infiltration techniques were not considered in isolation. Secondly, a number of the trials included did not involve any active dental treatment. Articaine has some advantages but these may be dependent upon the particular injection technique and the outcome measure employed.