The method of inferior alveolar block is the most common anesthesia procedure used in prolonged interventions in the mandibular arch: think, for example, of the canal therapies in this place; procedures that require great collaboration from the patient and, therefore, cannot be conducted except under an effective regime of anesthesia. In addition to the correct implementation of the injection, which is conditioned by significant rates of failure, it is important to assess what may be the most useful operational options in the event that it becomes necessary to perform additional injections.
In this regard, the Tupyota working group has conducted a systematic review of the literature, published in 2018 in the Australian Endodontic Journal, whose purpose is to evaluate the pain reduction interventions to be implemented during root canal therapy in lower molars. The study also considers one of the main unfavorable conditions from an anesthetic viewpoint, namely the irreversible acute pulpitis which, according to the authors is able to bring the above rate of failure from 15% up to 44-81%.
The review included only randomized clinical trials with samples of healthy adults with acute irreversible pulpitis (clinical evidence and subjective feedback by visual scale; radiographic negativity for other conditions). Several feasible measures were considered: modification of the injection technique, supplementary anesthesia, alteration of the characteristics of the administered drug, and premedication with other drugs.
In total, 113 records were screened from the databases PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, and MEDLINE. Of these, 22 full texts were considered, of which 17 were included in the qualitative analysis (overall the evidence was considered of good quality) and all but one record led to quantitative analysis (meta-analysis). The final data are relative to a sample of just over 1,500 patients. The indicator of efficacy was mostly clinical (lip numbness, possibly associated with cold tests), while two studies performed electrical stimulation tests. As far as subjective evaluation is concerned, the most used method is the visual analog scale (VAS), with few studies using verbal scales.
The results attest to the absence of statistically significant differences in terms of pulpal anesthesia when the additional techniques consist of buccal and lingual injection.
The results of quantitative interventions (volume increase) on the anesthetic solution, on the other hand, are significantly positive. The same applies to premedication with non-steroidal anti-inflammatory drugs, which is also the subject of a monograph article. As these are pharmacological interventions, the clinician must follow the absolute indications of toxicity and those relating to the state of the patient’s health.