Ingrown Toenail (Onychocryptosis) By Chris G Adigun, MD, Dermatology & Laser Center of Chapel Hill Reviewed / Revised Dec 2021 | Modified Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Topic Resources Ingrown Toenail Ingrown Toenail with Extensive... An ingrown toenail is incurvation or impingement of a nail border into its adjacent nail fold, causing pain.