Truncular anaesthesia of the inferior alveolar nerve is an essential procedure for dealing with the posterior area of the jaw in most endodontic–restorative and surgical procedures. The technique still used today is the classic one of inferior alveolar nerve block (IANB), which delivers anaesthesia to the pulpal area of the entire half-arch – from the third molar to the central incisor – in addition to the oral floor, bone and lining of the tongue and vestibular, the latter, however, roughly up to the premolar region, or before the emergence of the mental nerve. For this reason, the procedure may have to be completed with administration of buccal anaesthesia, effective precisely on vestibular soft tissues and periosteum at the lower molars.
The anesthesia of the hemi-mandible may however cause discomfort to the patient, especially in the postoperative period. In the cases where the areas to be treated are however the premolar elements and not the molars, there is a further technique of truncular anaesthesia available to the clinician, directed towards the terminal branch of the inferior alveolar nerve, the aforementioned mental nerve. This emerges from the homonymous canal normally located close to the premolar elements, and it is here that anaesthesia is administered, taking the name of mental/incisive nerve block (MINB). The site of administration corresponds to the interapical region of the two premolars, and is therefore better determinable by radiographically estimating the length of the respective roots.
This alternative has also been tested concomitantly with the perhaps more critical anaesthesiological situation, that of irreversible pulpitis. The 2016 Aggarwal study did not find significant differences between MINB and IANB for premolars having irreversible pulpitis, using the reference molecule for the class of drugs2% lidocaine, still widespread in several countries.
Now we come to a drug widely used in clinical practice in Western countries, including Italy: 4% articaine. In fact, Nydegger and Kammerer observed that the increased efficacy of this drug and this concentration is observed in buccal supplementation, rather than in primary administration (IANB).
With regard to the MINB method and its effects on the premolars, da Silva and Dressman’s work reported relatively high success rates by administering 4% articaine to volunteers, in the absence of pulpal inflammation.
The RCT of Gharabei and colleagues instead compared the two techniques in patients with a lower premolar in irreversible pulpate state – diagnosed by symptoms, cold test and pulpal electrical stimulation (accuracy of 96.88%) and objectively (bleeding at opening of chamber).
The first advantage detected is faster onset by the MINB: the previous indications in the literature were between 2 and 6 minutes on average, and the average figure in the study, 3 minutes, is located towards the lower limit. The difference was found to be statistically significant.
The IANB success rate was relatively high (81.2%) but still lower than that of the MINB (93.8%), a difference that is not statistically significant in this case. The difference is significantly different.
Finally, even the negative data for the post-injection pain was higher for the MINB, which in any case can be confirmed as a valid alternative.