In general, performing an additional anaesthetic injection is a valid and effective option when block anaesthesia (inferior alveolar block, inferior to the alveolar nerve (IAN)) does not provide a full anaesthetic effect. In this case, several techniques have been documented, and among them is intra-septal anaesthesia, which consists of the administration of the anaesthetic drug into the interdental septum. Saadoun and Malamed describe the procedure accurately, placing the insertion point in the keratinised gingiva at the exact centre of the papilla, equidistant from the two adjacent teeth. The advantages and disadvantages of the technique had already been discussed on these same pages in a previous article; the success rate is between 76 and 90%, depending on the criteria.
Recently, Webster’s working group, active at Ohio State University, evaluated the effectiveness of this technique in what is perhaps the most complex clinical condition in endodontics, at least from anaesthesiological point of view: the irreversible acute pulpitis.
The study was conducted on patients with pulpal inflammation of posterior teeth in the lower arch, with moderate to severe pain (evaluated with a visual analogue scale, VAS) and prolonged response to cold (clinical criteria for the diagnosis of irreversible pulpitis). The basic approach consisted of the classic technique of a lower alveolar block, conducted by the administration of 1 cartridge of lidocaine 2% with epinephrine 1:100,000. Once the sensation of numbness of the lower lip arose within 15 minutes (as proof of the correct implementation of the procedure), the block of the long buccal nerve (half a cartridge, with the same active ingredient) was delivered.
Patients who had started endodontic treatment and still reported a moderate to severe painful symptom (also, after evaluation by VAS) were then enrolled in the study and then treated with supplementary intra-septal anaesthesia. The additional procedure was conducted with a systematic computer-controlled release of anaesthetic (C-CLAD) rather than with a traditional syringe.
In the end, 100 patients were involved. Supplementary intra-septal anaesthesia provided deep anaesthesia to about one third (29%) of the patients who had reported lower alveolar block failure. On this basis, the procedure is not recommended for routine use. It is interesting to note that the CCLAD system itself can also be used as an alternative, in addition to the lower alveolar block, a technique which, delivered with a conventional syringe, is subject to high failure rates, even in the absence of an irreversible pulpitis condition.