Self-inflicted gingival injuries have been known to occur in children and adolescents secondary to a number of causes, including accidental trauma; fingernail biting; digit sucking; or sucking on objects such as pens, pencils, thread, or toothpicks. Of these causes, the one documented as the most common cause is habitual fingernail biting or onychophagia. This case report describes the gingival injury caused by habitual fingernail biting and the findings noted at the time of periodontal surgery. The potential ramifications of fingernail biting are discussed, and the steps necessary to ensure and preserve the dental health of the patient are identified.