ABSTRACT
BACKGROUND: Along with the emergence of porcelain-fused-to-metal (PFM) technique, Ni-Cr alloy has been shown to be the most available non-novel metal alloy used for preparation of PFM materials. The metal margin of Ni-Cr based PFM crown possibly produces some effects on periodontal tissue for it is primarily contacted with gingiva. OBJECTIVE: To investigate the influences of Ni-Cr alloy PFM crown on periodontal tissue. DESIGN, TIME AND SETTING: A retrospective case analysis was performed. All cases were from Department of Stomatology, the 476 Hospital of Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA between January 2006 and January 2007.PARTICIPANTS: Totally 23 maxillary incisors were included from 19 patients who averaged (32.5±10.8)years old and received tooth restoration using Ni-Cr based PFM crowns. Healthy contralateral corresponding teeth were used as controls. METHODS: All clinical operations were conducted by one dentist. Dental restoration principles should be strictly followed during preparation of dental prosthesis. A routine tooth preparation was performed. Specifically, gingival retraction cords were used for gingival recession, with a shoulder prepared 0.5 mm below the labial gingiva and concave shoulder thickness 0.5 mm. A temporary crown was made using silicon rubber. The normal physiological anatomical profile of complete crown should be recovered as possible while preparation. Dental axial crown overcontour should be increased within 0.2 mm. Finally, a permanent sticking was followed.MAIN OUTCOME MEASURES: At 6-9 months after wearing Ni-Cr alloy PFM crown, the gingival crevicular fluid was collected from affected and control teeth for quantitation and laboratory examinations (C reactive protein and tumor necrosis factor- a included),PARTICIPANTS: Alter placement of Ni-Cr alloy PFM crown which was clinically accepted, plaque index of affected tooth did not alter significantly, but gingival crevicular fluid volume, probing depth, sulcus bleeding index, and levels of C reactive protein and tumor necrosis factor-α were significantly greater in affected teeth than in control teeth (P < 0.05).CONCLUSION: Ni-Cr alloy PFM crown produces some harmful effects on periodontal tissue.