Topical anesthesia involves the most superficial portions of the tissue, naturally including the oral mucosa. It is, therefore, suitable for various uses in the dental clinic, first of all, pain control during the puncture of the needle. .
In this field, various pharmacological products can be found on the market, which differ on the basis of both the active ingredient, which can contain more than one molecule and the formulation (sprays, solutions, gels, ointments, even patches).
Despite an already satisfactory clinical use, these methods are not yet able to cover all the areas for which they would potentially be indicated. A study by Franz-Montan in 2012, for example, found that the most common product in this category – a lidocaine-prilocaine-based ointment – was not sufficient to reduce pain during the injection in the patient’s palate.
In the field of pharmacological research, the recent question has been how to increase the effectiveness of these products: the solution could come from the development of drug delivery systems. In other words, through chemical or physical methods, it is possible to optimize the efficiency and, at the same time, the safety of the transport of the drug molecule to the target site. An interesting review by the author mentioned above, in 2016, analyzed the current state of research: below are illustrated some of the solutions considered. However, please refer to the full text.
Within the biochemical options, the largest field is that of nanostructured carriers. Liposomes are vesicles that are formed by stirring phospholipids in water, thus being coated with a layer similar to the cellular layer (actually also in single or other configuration), within which the pharmacological molecules to be conveyed can be encapsulated. Among the local anesthetics, already in 1996, it has been demonstrated the greater effectiveness of an administration of 5% tetracaine compared to the application of a gel of 20% benzocaine. In the stomatognathic field, the persistence of disadvantages such as ineffectiveness in the case of palatal injection has been observed. Overall, however, the indications are interesting, especially if the method is hybridized with current nanotechnology. Lipid nanoparticles have been developed with the aim of overcoming some limits of liposomes, such as reduced physical-chemical stability or poor compatibility with hydrophobic pharmacological molecules. Due to their characteristics, they are particularly suitable for the topical and transbuccal pathways.
Among the physical methods, there has been a certain interest in understanding the physiological mechanisms underlying cryotherapy, in order to bring this option from an empirical to a protocol used. However, it is iontophoresis and microneedle that constitute real drug delivery options, respectively electrical and mechanical.