New discoveries have found exceptions to Mendel's basic laws, but none of Mendel's things have been proven to be flat-out wrong. Hail to the Father of Genetics ! The name is ma-ma-ma-ma-ma-Mendel.
Dental crowns should last on average from 10 to 20 years. Crowns are still subject to fracture and cavities, so it is important to take extra care in brushing and flossing around crowned teeth to prevent them from needing replacement too often.
Typically, a direct composite veneer lasts no more than 2 years. Plus they are more prone to staining or discolouration than other veneers. Their relative weakness means that they are more likely to break or fall off your tooth and they are not as natural looking as the other types of veneers.