Because the brackets and archwire are actually placed at the back of your teeth, they are virtually undetectable, allowing you to retain your normal appearance for the duration of your treatment. You doctor took courses specializing in the placement of these braces.
DEFINITION of 'Cost Center'. A department within an organization that does not directly add to profit, but which still costs an organization money to operate. Cost centers only contribute to a company's profitability indirectly, unlike a profit center which contributes to profitability directly through its actions.
http://www.sap-img.com/financial/difference-between-cost-centers-and-internal-orders.htm. Internal Orders are used for short term purpose like Trade Fairs, Job Fairs etc., where as Cost Centers are used for long term purpose to capture the day to day costs. Finally you have to settle the Internal orders to any cost object, wherein Cost centers are used to distribute/assess the costs of the company they are not settled.