Disadvantages of In-Office Whitening. 1  In-office bleaching is more expensive than take-home alternatives. 2  Its cost, on average, is $650, compared to $400 for take-home trays and under $100 for over-the-counter bleaching trays or whitening strips.
Planetary protection is a guiding principle in the design of an interplanetary mission, aiming to prevent biological contamination of both the target celestial body and the Earth in the case of sample-return missions.
Planetary boundaries is the central concept in an Earth system framework proposed by a group of Earth system and environmental scientists led by Johan RockstrÃ¶m from the Stockholm Resilience Centre and Will Steffen from the Australian National University.