Precautions before veneering are: 1.When suffering from periodontitis, ultrasonic cleaning and subgingival scraping should be carried out in advance, combined with periodontal surgery if necessary, and restoration should be carried out when there is no obvious redness, swelling and bleeding of the gums; 2.When cavities exist in the crown, decaying matter should be removed, cavity shape should be prepared and cavities should be repaired in time to prevent further development; 3.Removal of residual roots, residual crowns and teeth with obvious loosening and poor prognosis that exist in the dental row; 4.Active Before the restoration of the denture, the sharp bone tips, bone nodes and too short labial and buccal ties in the area covered by the abutment should be trimmed to avoid trauma and pain when wearing the denture; 5.periodontal examination should be conducted before the restoration of the fixed denture, and a reasonable design plan should be adopted to prevent the loosening of the abutment teeth.