ABSTRACT
Objective: To compare the influence of nickel-chromium alloy and gold-platinum alloy porcelain-fused-to-metal ( PFM ) on ultramicrostructure of canine gingival tissues, to survey the biological effects after PFM full crown restoration, and to provide data for selection of PFM materials. Methods; The nickel-chromium alloy and gold-platinum alloy PFM full crowns were used to repair canines in 3 healthy dogs. The microstructure of canine gingival tissue was observed through light microscope and transmission electron microscope. Apoptosis of canine gingival cells was detected by TUNEL method. Results; Under light microscope, inflammatory cell infiltration and partial bleeding were seen in the nickel-chromium alloy PFM full crown repaired canine gingival tissues. Under transmission electron microscope, large amount of cell apoptosis and neuclear condensation were observed in these tissues,and apoptotic index was 58.63% ±11. 12%. While under light microscope, inflammatory cell infiltration and partial bleeding were not seen in the gold-platinum metal PFM full crown repaired canine gingival tissues. Under transmission electron microscope, only small amount of cell apoptosis was detected in these tissues,and apoptotic index was 26. 90% ± 17. 35%. Statistical significance was found in both nickel-chromium alloy group and gold-platinum metal group compared to control group. There was also statistical significance between nickel-chromium alloy group and gold-platinum metal group in cell apoptosis numbers (P <0. 05). Cell apoptosis number in nickel-chromium alloy group was much higher than that in gold-platinum metal group. Conclusion; The negtive effects on ultramicrostructure of gingival tissue using nickel-chromium alloy PFM are more evident than using gold-platinum metal. When select PFM to repair defect teeth, it is better to select the inactive gold-platinum metal PFM as base crown.