Periodontal Ligament Injection (Intraligamentary Injection)
The periodontal ligament injection has been used for a number of years as either a method of obtaining primary anaesthesia for one or two teeth or as a supplement to infiltration or block techniques. The technique’s primary advantage is that it provides pulpal anaesthesia for 30 to 45 minutes without an extended period of soft tissue anaesthesia, thus being extremely useful when bilateral treatment is planned. It is useful in paediatric or disabled patients when there is concern of postoperative tissue trauma to the lip or tongue. However, its use should be avoided in primary teeth with a developing permanent tooth bud as there have been reports of enamel hypoplasia in permanent teeth following PDL injection. Because it is injected in a site with limited blood circulation it can be used in patients with bleeding disorders.
The PDL technique is simple, requires only a small amount of anaesthesia and produces instant anaesthesia. A ultra-short needle is placed in the gingival sulcus on the mesial surface and advanced along the root surface until resistance is met. In multi-rooted teeth injections are made mesially and distally. If lingual anaesthesia is needed the procedure is repeated in the lingual sulcus. Approximately 0.2ml of anaesthetic is injected.
Considerable effort is needed to express the anaesthetic solution placing a great deal of pressure on the anaesthetic cartridge with the possibility of breakage. There are syringes specifically designed to enclose the cartridge and provide protection from breakage. Since so little anaesthetic solution is necessary, Malamed suggests that when using a conventional syringe, expressing half the contents of the cartridge prior to injection will reduce the pressure exerted on the walls of the cartridge and reduce the likelihood of breakage.9,10
Computer-Controlled Anaesthetic Delivery System
“The Wand” (Milestone Scientific, Livingston , NJ) is a computer-controlled local anaesthetic delivery system. The system consists of a conventional local anaesthetic needle inserted into a disposable pen-like syringe. A foot-controlled microprocessor controls the delivery of the anaesthetic solution through the syringe at a constant flow rate, volume and pressure. It has been reported that block, infiltration, palatal and periodontal injections are more comfortable with the Wand than with conventional injection techniques.