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PURPOSE: To evaluate the marginal adaptation of full crowns using different adhesion methods which are commonly used in clinical.METHODS: 18 type IV stone dies were pored with a silicone impression.Wax patterns for full crowns were fabricated by a traditional method.Four symbol sites were made in every pattern and die.All the patterns were invested and casting to fabricate crowns.The crowns were seated on the dies according their symbol sites.Then they were divided into group ABC randomly.Glass ionomer cement was mixed and the crowns were cemented in the following methods: A)10 kg of static pressure cementation directly,B)dynamic pressure cementation directly,C)dynamic pressure cementation in three steps.A 10 kg load was then maintained on the crowns until complete cement cure.Their vertical marginal gap was taken pictures at four points around each crown by Olympus optical stereomicroscope before and after cementation respectively,measured using Image-Pro Plus 6.0,and made statistical analysis using SAS9.13.RESULTS: The marginal discrepancy before and after cementation:A)166±155 μm, B)93±64 μm,C)52±36 μm.Rank test(χ2=12.58,P=0.0019)revealed significant difference among the groups.CONCLUSIONS: Cementation would increase the marginal gap,dynamic pressure cementation in three steps had the best marginal adaptation,and this method is recommended in the clinical crown cementation.