Single tooth anaesthesia: a new anaesthesia concept
The local anaesthesia method most used today in dentistry is the nerve block, that is, the administration by injection of a compound which that can reach the nerve fibres carrying the sensitive afferents. Put simply, the main distinction, that between anaesthesia of the nerve plexus and the nerve trunk is based on the dimensions of the fibres themselves. However, it would appear to be useful to stress that there are some alternative techniques available to the dentist. These can be used alongside the classical method or replace it completely. Epiperiosteal (or subperiosteal) administration may have disadvantages when delivering the compound to intramedullary fibres, especially if there is thick cortical bone: this may lead to ineffectiveness or, at least, to a slowing of the anaesthetic action.
Single tooth anaesthesia (STA), a procedure introduced relatively recently, is of benefit in this regard. As a concept, it provides for a concentrated action at the level of a single dental element and requires the use of a computerised control system (also known as CCLAD).
STA is actually a particular form or, more correctly, a development of intraligamentary anaesthesia (PDL [Periodontal Ligament]) with which it therefore shares the biological pre-conditions. One of the advantages of intraligamentary anaesthesia, in addition to its fast and circumscribed action, is the low risk of toxicity, since in most cases only a small quantity of drug needs to be administered.
It has been established that the intraligamentary route’s efficacy partly relates to pressure. This does not mean the pressure needs to be exceptionally high, just sufficient to overcome tissue resistance. In fact, the method, which had already been introduced at the beginning of the 20th century, became very widespread from the end of the seventies with the appearance of the Peripress carriers, first as syringe guns and then as pens. Nowadays, the Peripress method, which can be very unpleasant for the patient, albeit only for a short time, is mainly used to reinforce nerve block, especially in the jaw and in cases where it is particularly difficult to achieve (irreversible pulpitis). Conversely, it may be ineffective if the periodontium is severely inflamed. In fact, it is currently recommended that normal syringes are also used in the PDL.
STA: localised anaesthesia and controlled pressure
The introduction of STA represents an instrument of considerable importance in daily practice. It actually provides a solution to the two main problems of intraligamentary anaesthesia, namely the difficulty of controlling the pressure manually and the lack of landmarks.
Indeed, the system provides constant pressure control (dynamic pressure-sensing, DPS). This basically guarantees a reduction in pain during administration, not only in comparison with Peripress, Ligmaject, or dental syringe, but also in comparison with conventional anaesthesia . In addition, the same instument is used to both guide the operator to where the anaesthetic is needed and to release it effectively.