Local anesthetics used in dentistry all belong to the amino-amide class, and these drugs usually are well tolerated and subject to a low risk of side effects. They are, therefore, suitable for widespread use, not least because they are generally effective.
On the other hand, it is difficult to think of effective drug treatment in 100% of cases. In the case of oral local anesthesia , the scientific evidence and also the empirical indications that clinicians know well lead to reflect on the possible causes of failure.
At the level of the jaw, where infiltrations are used in most cases (single or multiple in the case of intervention on more than one dental element), the success rate tends to be very high for all techniques. In the case of treatments conducted on the lower arch (and, in particular, in the posterior area), on the contrary, Block anesthesia is systematically required. The traditional technique, called inferior alveolar nerve block, although still most commonly used, comes from most authors as one of the most potentially frustrating procedures in the clinical setting, with a success rate that, according to some studies, would not exceed 75-80%.
This problem and also the discrepancy with the upper jaw should first be related to the morphological difference. The mandible has a thicker and denser cortical, able to hinder the spread of the anesthetic solution in the bone marrow. A secondary reason is represented by the anatomical variability that can affect the mandibular branch of the trigeminal nerve.
Starting from the initial considerations of this treatment, Nelly Badr and Johan Aps have proposed to investigate whether, and to what extent, the success of local dental anesthesia is related to the pharmacological molecule, regardless of anatomical aspects.
The authors conducted a literature review that considered a total of 30 scientific studies that were screened from a pool of 79 full texts, selected from the main medical-scientific database, and representative of the period 2008-2018.
Articaine is the most common amide molecule (13 in vivo studies and 4 revisions) indicated to be the most effective. 11 studies have made a comparison between two different molecules without finding significant differences in terms of effectiveness but reported a considerable increase in the administration of a high volume (i.e., that exceeded the single tube vial).
No increase in efficacy was reported as a result of the increased concentration of the vasoconstrictor, except for the report of a single study that, however, considered the little-used clonidine (combined with lidocaine) and not adrenaline. Similar indications are related to the use of other additives such as meperidine and mannitol.