What can clean out gravel or dirt from wound on forehead? (photos)

4 month old indented. Scar. Is somewhat slowly healing and most Drs say not to excise however last Dr said there is some remaining dirt or gravel which I always thought Also . He wants to clean the gravel and stitch the wound ER Dr was awful and refused to clean or irrigate the wound Question—-Will any non surgical modalities help exfoliate any dirt or gravel to help wound healing instead of cutting ?———note I won’t do co2