The influence of the impacted mandibular third molar extraction on the distal periodontal tissue of the mandibular second molar

The periodontal bone defect might be formed on the distal surface of the second molar root followed the extraction of the mandibular third molar. The occurrence and prognosis of the complication would be influenced by the age of extraction, the impaction level of the third molar, local inflammation, health state of adjacent tooth, etc. The periodontal bone defect of the second molar would be severer and had poorer prognosis in the case of extraction for the older patients, deeper impaction of the third molar, local inflammation, food impaction, adjacent tooth caries. From the prophylactics, it was beneficial for the prevention of the complication or reducing severity of the complication when the extraction of lower third molar was performed before the age of 25 years old. The periodontal bone defect could be effectively repaired by transplanting bone graft.