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.
Civil defense, civil defence (see spelling differences) or civil protection is an effort to protect the citizens of a state (generally non-combatants) from military attack. It uses the principles of emergency operations: prevention, mitigation, preparation, response, or emergency evacuation and recovery.