Lie Detector 
A lie detector in a dream represents a test which you are trying to pass. You may have a secret which is bothering you and you are afraid of being caught. You may also have a big interview ahead, or a final exam, which is causing you stress.
Orthodontist
An orthodontist in a dream represents worry about your control over others' perceptions of you. To have an adjustment at the orthodontist in a dream indicates your need to reevaluate the signals you give to others.