A B757-200 Captain describes the events that contributed to a twenty minute departure delay involving efforts to fix a broken First Class seat headrest and Captain's concerns about a temporary MEL for the headrest that initially had been issued verbally; instead of being sent to the flight crew.

Narrative

Approximately 25 minutes prior to departure the Lead Flight Attendant notified us of a broken First Class seat headrest. The Flight Attendant stated that the passenger in the seat was upset and wanted the seat fixed and wanted to talk to a Passenger Service Supervisor. The Supervisor talked to the passenger and told me that we should do something about the broken headrest. We had already called Maintenance and they worked on the seat but could not fix it; so the seat was put on MEL which made us late. When the MEL was sent by Dispatch; [via] ACARS; it was a temporary MEL; so we had to have Maintenance make us a copy of the temporary MEL so we could be legal. By the time we got our logbook back we were more than 20 minutes late. The cause of being late was the temporary MEL and the flight crew and maintenance performing their jobs as trained. Temporary MELs have caused problems more than once because of the time required to fax/print a copy for the flight crew to have onboard the aircraft. A very simple suggestion: any time an MEL with a 'T' on it is put on an aircraft; a copy or fax of the MEL should automatically be sent to the crew. Verbal issuance of the 'T' MEL is not a good idea due to lengthy complicated MELs which can be confusing and need to be carefully read.