You can achieve top quality scans by bending the book as much as possible for a minute then applying soft pressure on the book as it lays on the flat bed during the scan.
See, for example, this book which I digitized:
http://libgen.rs/book/index.php?md5=1DD970651472FC187EDFDBFC7FEA64FE
The book is still intact, albeit with the side cover a bit stretched lol