Night guard bleaching refers to:
Bleaching techniques 

For vital teeth 

– Home bleaching technique/night guard vital bleaching.
– In-office bleaching:
i. Thermocatalytic 
ii. Nonthermocatalytic 
iii. Microabrasion. 

For nonvital teeth 

– Thermocatalytic in-office bleaching 
– Walking bleach/intracoronal bleaching 
– Inside/outside bleaching 
– Closed chamber bleaching/extracoronal bleaching 

Laser-assisted bleaching.
Laser activated bleaching
Dentist prescribed home applied technique
Thermobleaching
Photo bleaching