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What is Night guard bleaching refers to: and explain in detail?
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.