Effect Of Porcelain-Fused-to-Metal Crowns With Different Metal Base Alloys On The Gingiva

Objective:It has been decades since porcelain-fused-metal restoration was applied into prosthetics. In spite of its satisfactory aesthetical and functional restoration, it was reported that there were some gingival inflammatory symptoms such as flare, bleeding, the discontinuation of the gingival margin curve in different time after the restoration.The gingivitis can be assessed by observing the gingival color, figure and texture as well as probing. Among many assessment indexes, gingival index (GI) is considered to be an effective one which has been used for the purpose of observing the curative effect and scientific research for years. It was reported that the quantity and quality of gingival crevicular fluid (GCF) may change under the inflammatory conditions. Some researchers supported that GCF is one kind of inflammatory diffusate which can be detected before other clinical superficial syndromes appear. Therefore, GCF has been viewed as an objective index to evaluate the health of gingiva. Besides, the functional disorder of the mediators of ante-inflammation was one of main factors which caused inflammation. Among many cytokines which were secreted in the gingival crevice, IL-6 and TNF-αwere regarded as two active factors that played a very important role in the progressing of the periodontitis, and were taken as indexes to explore the pathogenesy and host response.There were many factors that can result in gingivitis after restoration such as cervical design of the dental prosthetic restoration, different kinds of metal base alloy, faulse operation. With the development of dental material science, the alloys and porcelain cement used in PFM restoration have improved a lot. In recent years, many studies have been focused on the long-term gingival effect of PFM with different metal base alloys. Ignoring optimizing the cervical design and the operation, this study observed the effect of porcelain-fused-to-metal crowns with different metal alloy base on the gingiva, then compared and evaluated their clinical effects, and verified their different nature. In doing so, it can guide the selection of restoration, meanwhile, the immune mechanism of periodontal symptom after restoration may also be explored.Method:Over the period from September to December in 2005, according to the definite acceptance and exclusion standards, 60 teeth from 60 patients who wanted to restore with PFM in the department of stomatology of China-Japan Union Hospital of Jilin University were selected and divided into 6 groups randomly. With the informed consent, they were restored respectively by PFM crowns with 6 different alloys. They were Ni-Cr alloy, gilt Ni-Cr alloy, Ni-Cr alloy with titanium, gilt Ni-Cr alloy with titanium, palladium alloy, high gold alloy. To get a convenient discussion,Ni-Cr and Ni-Cr with titanium were called base-metal alloy group; gilt Ni-Cr and gilt Ni-Cr with titanium were called gilt group; palladium alloy was called semi-noble alloy group; high gold alloy was called noble alloy group.The contralateral or occlusal homonymy natural teeth were healthy and treated as their control teeth.On the basis of tooth preparation requirements by Ma Xuanxiang, every patient's time can be recorded.6 months later, GCF can be collected by filter paper strips; then the concentration of IL-6 and TNF-αcan be detected by ELISA; afterwards GI can be surveyed. The data was analyzed with SPSS.10.0, and the size of test was established as 0.05.Results:1. Compared with respective control group, with regard to these 4 indexes, there were significant differences in base-metal alloy group; contrarily, there were no significant differences in semi-noble alloy group and noble alloy group. For the gilt group, there were significant differences with GI, GCF and TNF-α, and no differences with IL-6.2. With 4 indexes, there were no significant differences between noble alloy group and semi-noble alloy group. With GI, GCF and TNF-α, there were significant differences between these two groups and gilt group, but with IL-6, no significant differences between them were found. With 4 indexes, there were significant differences between gilt group and base-metal alloy group. There were no differences between the two kinds of materials in gilt group; and the same was true in base-metal alloy group.Conclusion:1. Different metal base alloys had different effects on the gingiva.2. According to the effects on the gingiva, it can be concluded that noble alloy group and semi-noble alloy group had the least effect on the gingiva, but there were no differences between them. Moreover, the second least group was the gilt group, and the base-metal alloy group had the most effect on the gingiva. There were no differences between the two kinds of materials in gilt group; the same was true in base-metal alloy group.3. These 4 indexes,namely GI, GCF, IL-6 and TNF-α, can reflect the effect of different metal base alloy of PFM on the gingiva. Being used as evaluating indicators, they were definitely valuable for appraising the clinical effect of different PFM.