Vasoconstrictors in dentistry

Pharmacological profile of the baseline anesthetic

In modern surgical dentistry, formulations containing vasoconstrictors are most commonly based on articaine. When analyzing the pharmacological properties of this active substance, its specific features must be taken into account. First, at commonly used therapeutic concentrations, articaine completely lacks surface-anesthetic efficacy, which precludes its use for topical anesthesia. Second, when performing infiltration and conduction anesthesia, this drug demonstrates outstanding results: the efficacy of local pain control in adult patients reaches 95–100%. In terms of clinical potency, articaine reliably outperforms such well-known anesthetics as lidocaine, prilocaine, and mepivacaine.

Special attention should be paid to the drug's action under conditions of pronounced tissue inflammation. As is well known, the inflammatory process is accompanied by acidosis; however, articaine loses its pharmacological activity in the acidic environment of inflamed tissues to a significantly lesser extent compared to the vast majority of other anesthetics. It is precisely this feature that makes it the absolute drug of choice in the treatment of patients with severe purulent-inflammatory processes of the maxillofacial region.

Precautions and management of high-risk patients

The addition of a vasoconstrictor to a dental cartridge fundamentally changes the approach to safety assessment. Special, heightened caution is required when prescribing solutions containing adrenaline to patients suffering from severe somatic conditions. Such conditions include various cardiovascular and endocrine diseases, in particular: thyrotoxicosis, diabetes mellitus, congenital and acquired heart defects, and arterial hypertension. Furthermore, the clinician is required to take a meticulous pharmacological history, as the use of vasoconstrictors is extremely hazardous in patients taking specific drug classes, such as $\beta$-blockers, tricyclic antidepressants, and monoamine oxidase (MAO) inhibitors.

To ensure safety during pregnancy and lactation, as well as in patients with heart failure, diabetes mellitus, and thyrotoxicosis, the dentist must use strictly defined formulations. In these clinical situations, the drugs of choice are either a 4% articaine solution with adrenaline in a safe 1:200,000 dilution, OR plain articaine without the addition of a vasoconstrictor.

Prevention of complications and side effects

A fundamental rule for the injection of any local anesthetic, especially one containing a vasoconstrictor, is the prevention of its accidental entry into the bloodstream. Prior to directly injecting the solution, performing an aspiration test is strongly recommended and mandatory. Complications from accidental intravascular administration can be catastrophic. This is especially hazardous with the careless use of a 4% articaine solution with a high, aggressive concentration of adrenaline (1:100,000). Such an error can lead to acute ischemia of the entire injection site, which subsequently inevitably threatens to progress to deep tissue necrosis.

Overall, adverse reactions to modern articaine-containing drugs are relatively rare in clinical practice, occurring statistically in only 0.13–0.26% of all patients. Nevertheless, they may present in the following forms:

• Allergic reactions: ranging from cutaneous manifestations (urticaria) and angioedema to life-threatening anaphylactic shock.
• Local reactions: development of edema and local inflammation directly at the injection site.
• Systemic reactions: onset of headache, nausea, as well as moderately pronounced hemodynamic and normal heart rhythm disturbances.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Mechanisms of tissue acidosis development in purulent-inflammatory processes of the maxillofacial region.
• Algorithm and technique for performing a proper aspiration test using a dental cartridge syringe.
• Clinical presentation and emergency management protocol for anaphylactic shock in a dental setting.
• Comparative profile and pharmacokinetics of articaine, lidocaine, prilocaine, and mepivacaine.
• Pathogenesis of ischemia and necrosis development following intravascular administration of high doses of adrenaline.

Other topics in "Chapter 4. Anesthesia in Oral Surgery (S.A. Rabinovich, S.T. Sokhov)"

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