Hinge for the mutual engagement of panels comprising two opposed wing-like means (1, 2), each of them comprising a basic body provided with through-holes for housing screws for fastening to a panel and with engagement means with the wing-like element complementary therewith provided at a lateral end of said basic body, at the end of the mutual engagement area locking means being provided for the engagement of one wing with respect to the other, - the former of said wing-like means comprising a basic body, having a generically quadrilateral profile having a rounded end housing a circular-profiled cavity therein; - the latter of said wing-like means in turn comprising a basic body, having a partially polygonal and partially rounded profile at the end engaging with the complementary wing-like means, said rounded portion making up a cylindrical body which tapers about halfway through to form a pin; - the locking element being provided with engagement and manoeuvring means on the outer surface and sealing engagement means with complementary sealing engagement means provided in the mutual engagement area of said wing-like means and is composed of a disc-shaped body which carries, on the outward surface, an engagement and manoeuvring element and, on the inward surface, a carousel element, the latter having a hollow central cylindrical body; - said cavity of said basic body of the former of said wing-like means being provided with a thickening halfway through along its height starting from the area of contact and engagement with said pin provided on said latter wing-like means, said thickening being provided with two invitation grooves (17, 18), having different widths, the shape of said thickening halfway through along its height determining the forming of a housing chamber of the engagement surface of said locking element, wherein on the surface of said thickening, which identifies said chamber, opposite slits are provided for housing an engagement tooth made of a flexible material provided on said locking element. - the former of said wing-like means comprising a basic body, having a generically quadrilateral profile having a rounded end housing a circular-profiled cavity therein; - the latter of said wing-like means in turn comprising a basic body, having a partially polygonal and partially rounded profile at the end engaging with the complementary wing-like means, said rounded portion making up a cylindrical body which tapers about halfway through to form a pin; - the locking element being provided with engagement and manoeuvring means on the outer surface and sealing engagement means with complementary sealing engagement means provided in the mutual engagement area of said wing-like means and is composed of a disc-shaped body which carries, on the outward surface, an engagement and manoeuvring element and, on the inward surface, a carousel element, the latter having a hollow central cylindrical body; - said cavity of said basic body of the former of said wing-like means being provided with a thickening halfway through along its height starting from the area of contact and engagement with said pin provided on said latter wing-like means, said thickening being provided with two invitation grooves (17, 18), having different widths, the shape of said thickening halfway through along its height determining the forming of a housing chamber of the engagement surface of said locking element,