Mechanism of Action of Dental Electro-anaesthesia

Abstract

NEWMAN¹ has proposed that the analgesia produced by passing a small electric current from the dental drill (positive) to a hand electrode (negative) is due to anodal blocking of nerve fibres within the tooth. Fields et al.² feel that the likely mechanism is electrocoagulation of odontoblasts in the dentinal tubules under the site of drilling. The difference is clinically important, for anodal blocking is a harmless reversible process whereas the destruction of odontoblasts leaves permanent dead tracts in the dentin under the site of application of the current. These two mechanisms can be separated by applying stimulation and electro-analgesic current to different sites on the same tooth, since the local mechanism (electrocoagulation) would have no effect in blocking a stimulus applied elsewhere.