The laser and gel treatments sensitize them further, but the effect is temporary.
British Dictionary definitions for sensitize
to make or become sensitive
(transitive) to render (an individual) sensitive to a drug, allergen, etc
(transitive) (photog) to make (a material) sensitive to light or to other actinic radiation, esp to light of a particular colour, by coating it with a photographic emulsion often containing special chemicals, such as dyes