Studying the chemical composition of stars in detail is important in modern stellar astrophysics. In particular, since M-type dwarfs are the most abundant main-sequence stars in the Milky Way and have main-sequence lifetimes longer than the age of the universe, they stand as excellent objects to study the structure and chemical composition of the Galaxy. Additionally, M dwarfs constitute relevant targets in the search of exoplanets, since their faintness and lower masses facilitate the detection of Earth-like exoplanets in their habitable zone. These studies could be vastly increased with prior knowledge of stellar chemical composition. However, this duty is often challenging in the case of M dwarfs, whose spectra are complex due to the presence of prominent molecular features, in comparison to those of solar-type stars. For these reason, several studies have investigated M-dwarf metallicities using wide physical binary systems.