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- Local anaesthesia for children - J. G. Meechan
5.1 INTRODUCTION
This chapter considers the use of local anaesthesia in children and describes methods
of injection that should produce minimal discomfort. The complications and
contraindications to the use of local anaesthesia in children are also discussed. The
major use of local anaesthetics is in providing operative pain control. It should not be
forgotten, however, that these drugs can be used as diagnostic tools and in the control
of haemorrhage.
5.2 SURFACE ANAESTHESIA
5.2.0 Introduction
Surface anaesthesia can be achieved by physical or pharmacological methods (topical
anaesthetics). One physical method employed in dentistry involves the use of ethyl
chloride. It relies on the latent heat of evaporation of this volatile liquid to reduce the
temperature of the surface tissue to produce anaesthesia. This method is rarely used in
children as it is difficult to direct the stream of liquid accurately without involving
associated sensitive structures such as teeth. In addition, the general anaesthetic action
of ethyl chloride should not be forgotten.
5.2.1 Intraoral topical agents
The success of topical anaesthesia is technique dependent. Topical anaesthetic agents
will anaesthetize a 2-3 mm depth of surface tissue when used properly. The following
points are worth noting when using intraoral topical anaesthetics:
- The area of application should be dried.
- The anaesthetic should be applied over a limited area.
- The anaesthetic should be applied for sufficient time.
A number of different preparations varying in the active agent and in concentration
are available for intraoral use. In the United Kingdom the agents most commonly
employed are lidocaine (lignocaine) and benzocaine. Topical anaesthetics are
provided as sprays, solutions, creams, or ointments. Sprays are the least convenient as
they are difficult to direct. Some sprays taste unpleasant and can lead to excess
salivation if they inadvertently reach the tongue. In addition, unless a metered dose is
delivered, the quantity of anaesthetic used is poorly controlled. It is important to limit
the amount of topical anaesthetic used. The active agent is present in greater
concentration in topical preparations compared with local anaesthetic solutions and
uptake from the mucosa is rapid. Systemic uptake is even quicker in damaged tissue.
An effective method of application is to spread some cream on the end of a cotton bud
(166HFig. 5.1). All the conventional intraoral topical anaesthetics are equally effective
when used on reflected mucosa. The length of time of administration is crucial for the