The clinical effectiveness of a disposable aspirating syringe.

In 18 per cent of mandibular block injections and 2 per cent of maxillary infiltrations blood appeared in the carpule aspiration. In 500 mandibular block injections when an aspirating syringe was used in 250, only 0.7 per cent patients suffered toxic side effects compared with 5 per cent when a conventional non-aspirating syringe was used.