[Moiré effect. Application in medicine and dental technology]

Moiré effect is an optical phenomenon that occurs when two similar arrays of alternately opaque and transparent lines or dots are superimposed upon each other. Superimposition of two such similar, but slightly different, line arrays causes interference between the arrays; the interference results in the formation of moiré fringes. There is a definite relationship between the pitches of the two arrays and the spacing of the fringes. Therefore, given the pitch of one of the arrays and the distance between the moiré fringes, the pitch of the other array can be calculated. The moiré effect can be used to determine the development of cutaneous tumors in a very short time-frame and to assess the measurement of dental eruption within 20 minutes. The 3-D facial, palatal and dental morphology can thus be evaluated very accurately. The CAD/CAM dental technology is actually possible due to the moiré effect.