Representative micro-Raman peak shift (952-962 cm−1) imaging of the demineralized dentin layer. (A) The Raman peak shift in the range of 952-962 cm−1 is associated with ν1 vibration of PO43- in mineral; the images generated based on this peak range can be used to identify the presence of mineral in the demineralized layer; (B) Adper™ Prompt L-Pop (APLP), 15s with rubbing; (C) 35% phosphoric acid gel, 15 s, without agitation; (D) 35% phosphoric acid gel, 15 s, with agitation.