Many silents were reworked to include dialogue or other sound effects
during the transitional period.   Perhaps the most famous example
was Howard Hughes' _Hells Angels_ which was already done when talkie
technology hit the industry.  Hughes redid dialogue scenes at marvellous
expense, replacing key personnel to do so.
 
Pages of _Variety_ from the time will disclose other films being redone
with dialogue  added.
 
Jonathan eBreton
UMBC