How to find percentage data change after last full backup?
Well, you should be able to fix his procedure with a very simple change. Change this line:

SELECT @dbccPageString = 'DBCC PAGE (' + @dbName + ', '


To this:

SELECT @dbccPageString = 'DBCC PAGE (' + QUOTENAME(@dbName) + ', '


But really, fix your database names. This is not the last thing that will break as a result.