Complex sentence: The first, referred to as the "standardized technique" was developed by Ingle in 1961, and had disadvantages like the potential for loss of working length and inadvertent ledging, zipping or perforation.
Split into simpler sentences: The first, referred to as the "standardized technique" was developed by Ingle in 1961. The classical procedure, first described in the mid twentieth century, has disadvantages like the potential for loss of working length and inadvertent ledging, zipping or perforation.