Aspiration in oral local anaesthesia. Frequency of blood in cartridges in an undergraduate student material.

In an experimental study, comprising 1662 injections performed by 120 dental students, the number of aspirations, which were positive for blood was recorded. The highest frequency of positive blood findings in the cartridges by aspiration was found with the mandibular block injections (11,3 per cent). The results are similar to those described in earlier investigations, in which experienced clinicians made the injections. Thus, the clinical experience does not seem to be of determining importance in this connection.