CORINA MARILENA CRISTACHE, EUGENIA EFTIMIE TOTU, GHEORGHE CRISTACHE, AURELIA CRISTINA NECHIFOR, INGRID IOANA PINTILIE MELATONIN AND HYALURONIC ACID IN PERIODONTAL DISEASE The aim of the present paper was to highlight the individual effects of melatonin (MEL) and hyaluronic acid (HA) on periodontal structures and repair mechanism and to investigate a possible synergic effect and if each component of the proposed mixture (MEL-HA) would maintain their specific characteristics, when using booth active principles, for a topical application. A comprehensive review of the recent literature focusing on the role of MEL and HA in periodontal therapy, as well as on the use of both active compounds and possible synergic effect, have been conducted. An experimental investigation, using the FT-IR analysis, both the individual spectra of each component and the complex matrix obtained was performed. The experimental data obtained from our study proved that no structural changes occurred at the level of the functional groups of the components. Therefore, it is expected that the obtained formulation to be highly efficient for the treatment of periodontal disease, as it would combine the specific local action of MEL and HA.