The conventional technique of inferior alveolar nerve block remains today the most widely used technique in the approach to posterior of the mandibular teeth. To reduce the rate of failures that can be attested to around 20% with peaks of 35-45, thus making the method more predictable, several procedural corrections have been proposed.
In 2013 Chakranarayan and Mukherjee described a procedure called arched needle technique. This maintains the target site of the conventional technique; i.e., the pterygomandibular space. The modification consists in the approach to the medial surface of the mandibular branch, which does not occur through an incidental angle, but through a perpendicular angle. This is achieved by bending the needle according to a precise criterion.
The author experimented with the technique on a total of 100 patients who were treatment planned to extract a third molar including the lower second molar.
The anesthetic procedure involves positioning the backrest of the dental unit at an angle of about 30 degrees, with the doctor standing at 8 o’clock for the right side and at 11 o’clock for the left side (indications for right-handed operators). The use of a 27 gauge (25 mm) long needle is recommended. The anatomical markings of the classic technique are maintained, with respect to which the insertion site is slightly to the distal. Once inserted for 4-5 mm, the needle is bent in the posterioral-mesial direction: in other words, with the concavity facing the mandibular nerve. This angle allows perpendicular access to the pterygomandibular space and is maintained until it is contact with the periosteum. After a slight retraction and the aspiration test, 1.5 cc of anesthetic solution is administered, leaving the residue of the cartridge for anesthesia of the long buccal nerve.
The success rate found by the authors—this evaluation is completely similar to that provided for the conventional technique—is 98%, with the anesthetic effect occuring within three to five minutes. The authors also reported the following operational problems: four minimal blood aspirations, five cases of early contact with the bone and, on the contrary, two cases of insufficient depth.
Bhargava, in a speech in 2013, which was recorded in the Journal of Oral and Maxillofacial Surgery, objected that the choice of bending the needle, however, by hand, could be unsafe: from this point of view, the group that introduced the technique had carried out a preventive in vitro trial, observing a lack of increase in the risk of breaking the needle. Moreover, Bhargava indicates that in the inferior alveolar block the method most at risk as far as this complication is concerned, remains extremely infrequent.
This aspect represents, however, the main objection of the method, probably not for the actual risk, but for the fact of maintaining an element of dependence on the operator.