Enkephalins are a family of molecules included in the larger complex of endogenous opioids, neuropeptides capable of binding opioid receptors. They express an analgesic action superior to that of morphine but very rapid, as they are degraded by localized peptidases near the same receptors.
Opiorphin is in turn an endogenous opioid of more recent discovery, endowed with a powerful painkiller effect deriving from the ability to interfere with the degradation of endorphins, as said main limitation to the action of the same.
Such discoveries, as also those of numerous other mechanisms of regulation of the activity of the enkephalins (exactly through the block of their degradation), have aroused a great interest for these drugs, intended as “physiological anesthetics.” The opiorphin, then, presents the peculiarity to concentrate strongly to saliva level. This makes it a biomarker with a potential interest in the field of dentistry.
A first work of 2017 (Ozdogan and colleagues, Archives of Oral Biology) aims to assess the correlation between opiorphin levels in patients exposed to two important conditions of dental pathology. In this case, the study involved a total of 15 cases of irreversible acute pulpitis and 24 cases of symptomatic apical periodontitis. Samples were evaluated at the time of diagnosis, i.e. in the active pain phase, and in two different phases after endodontic treatment: at 7 days (no pain, in the process of healing) and at 30 days (no pain, cured). The analysis showed significantly higher preoperative levels of opiorphin in patients with irreversible pulpitis. This would indicate opiorphin as a marker of pulpal inflammation, strongly related to reported pain.
In the same year, the Parida group presented (Journal of Stomatology, Oral and Maxillofacial Surgery) a study aimed at evaluating the response to local anesthesia through the evaluation of the trend of the same salivary levels of opiorphin.
The work involved a total of 144 patients, equally divided into 4 groups depending on the type of anesthetic method conducted (lower alveolar nerve block, local infiltration, infraorbital nerve block, and upper posterior nerve block). Each group was divided into 3 subgroups based on the molecule used (lidocaine, articaine, and bupivacaine). In this case, the indications of variation of opiorphin levels are not supported by statistical significance. This could be related to the variety of techniques and drugs investigated: the authors therefore propose to carry out more circumscribed investigations.
In the final analysis, Salarić’s study, also from 2017, considered salivary levels of opiorphin in the context of a picture of chronic pain that is difficult to read and of diagnostic and dental interest: the burning mouth syndrome.
In conclusion, investigations of this type appear evidently useful for the understanding of physiological mechanisms – of nociception in this case -, but in the future, they also demonstrate clinical potential. In the near future, in fact, it will be possible to adapt the therapy to the needs of the individual patient also on the basis of the molecular study of the biological samples collected; for its easy availability, saliva is in this sense one of the most suitable.