It has been claimed that anaesthesia of mandibular pulpal and lingual soft tissue, as well as maxillary palatal soft tissue, results following buccal infiltration of the local anaesthetic Ultracaine (articaine HC1). However, this has never been scientifically proven and the aim of this investigation was to test these claims by comparing articaine to a standard anaesthetic, Citanest (prilocaine HC1). In order to study this, a double blind, randomized trial was conducted in healthy adult volunteers. In these subjects, the ability to induce maxillary and mandibular anaesthesia following buccal infiltration with articaine (as compared to prilocaine given contralaterally), was determined by measuring sensation to electrical stimulation at the tooth, buccal and lingual soft tissue at each of the four non-carious, non-restored, second molars. Results showed that there were no statistically significant differences between articaine and prilocaine in their ability to induce anaesthesia for any tissue at any of the six sites (p greater than 0.05) as determined by chi-square analysis. Analysis of effect on sensation for 25 minutes post-administration also failed to demonstrate a difference between the two drugs. Therefore, these data are not consistent with superior anaesthesia efficacy by articaine at any site, including the mandibular pulpal, lingual or maxillary palatal tissues, in the second molars studied.