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.
1. Gear System. An interlocking set of gears, called a planetary system, helps you ride up a hillâor go faster on a flat. Depending on the gear, the driver unit either first spins outer ring gears, or the planetary gears deeper in the hub, rotating around sun gears near the center. In all, there are 11 combinations, offering a range thatâs the theoretical equivalent of an 11-45âtooth cassette.