| Objective:To study in vitro the effect of different marginal designs and polishing methods on the FDI scores of marginal adaptation,surface gloss and color match and translucency when ceramic partial veneers are used to restore incisal angle defect of maxillary central incisor,and to evaluate the aesthetic effect of ceramic partial veneers of anterior teeth,providing methods and reference basis for the clinical application of ceramic partial veneers.Methods:Thirty maxillary central incisors randomly that meet the criteria were selected for the Experiment 1,and the tooth tissue at the mesial incisal angle were removed to simulate the mesial incisal angle defect.Randomly divided into three groups according to different design of edge(n = 10): Group A with no preparation,Group B with knife-edge,and Group C with slight chamfer edge.After tooth preparation,make ceramic partial veneers restorations,bond it in place,and remove excess resin adhesive from the marginal area.Under naked eye observation and camera photography,three prosthodontics doctors scored each sample for marginal adaptation,surface gloss,and color match and translucency in accordance with the FDI scoring standards.The average of the three doctors’ scores for each sample was taken as final score.Thirty maxillary central incisors randomly that meet the criteria were selected for the Experiment 2,and the tooth tissue at the mesial incisal angle was removed to simulate the mesial incisal angle defect.All samples were prepared with knife-edge.Ceramic partial veneers prosthesis was fabricated and bonded in place.Randomly divided into three groups according to different polishing methods(n = 10),the first group is OneGloss polishing,the second group is rubber wheel polishing + fine polishing with diamond particle grinding head,and the third group is diamond bur or green stone finishing and smoothing + rubber wheel polishing + fine polishing with diamond particle grinding head.Under naked eye observation and camera photography,three prosthodontics doctors scored each sample for the marginal adaptation,surface gloss,and color match and translucency before and after polishing in each group according to the FDI scoring standard.Take the average of the scores of three doctors as the final score for each sample,and observe the labial marginal area of ceramic partial veneers in a stereoscopic microscope 50 ×.SPSS 27.0 software was used for data analysis.If the data follows normal distribution and homoscedasticity,methods such as One-Way ANOVA,SNK test and Paired Sample t-test were used.If not,Kruskal-Wallis,Wilcoxon and Dunn tests are used to compare whether there are statistical differences in the scoring results of various indicators between different marginal designs,different polishing methods and between before and after polishing.In all tests,the significance level was set at α = 0.05.Results:1.The marginal adaptation scores of the no-prep,knife edge,and slight chamfer edge groups were(3.00 ± 1.58),(2.00 ± 1.00)and(1.67 ± 1.00),respectively.The comparison of the three groups showed that the marginal adaptation scores of the slight chamfer edge group were better than those of the no-prep group(P < 0.05),and the marginal adaptation scores of the knife-edge group were better than those of the no-prep group(P < 0.05),and the difference in marginal adaptation scores between the slight chamfer edge group and the knife-edge group was not statistically significant(P > 0.05).The surface gloss scores of the no-prep,knife-edge,and slight chamfer edge groups were(2.00 ± 0.75),(2.17 ± 0.50),and(2.17 ± 0.50),respectively,with no statistical difference(P > 0.05).The color match and translucency scores of the three groups were(1.67 ±1.17),(1.50 ± 0.42),and(1.33 ± 0.75),respectively,with no statistical difference(P >0.05).2.The scores of marginal adaptation after using One Gloss to polish the labial area of ceramic partial veneers were worse than before polishing(P < 0.05),and there was no significant difference in surface gloss,color match and translucency scores compared to before polishing(P > 0.05).The marginal adaptation and surface gloss of the ceramic partial veneers on labial areas after using rubber wheel polishing + fine polishing with a grinding head containing diamond particles were significantly better than before polishing(P < 0.05),and the color match and translucency scores were worse than before polishing(P < 0.05).The scoring results of the marginal adaptation and surface gloss of the ceramic partial veneers after using diamond bur / green stone finishing and smoothing + rubber wheel polishing + fine polishing with a grinding head containing diamond particles were significantly better than before polishing(P < 0.05),and the color match and translucency scores were worse than before polishing(P < 0.05).The difference in the scores of three groups after polishing the marginal areas of ceramic partial veneers shows that the marginal adaptation scores of the rubber wheel polishing +fine polishing group with diamond particles(1.67 ± 0.42)and the diamond bur / green stone finishing and smoothing + rubber wheel polishing + fine polishing group with diamond particles(1.33 ± 0.34)are better than those of the One Gloss group(2.33 ± 1.50)(P < 0.05);The surface gloss scores of the rubber wheel polishing + fine polishing group with diamond particles(1.00 ± 0.33)and the diamond bur / green sand stone finishing and smoothing + rubber wheel polishing + fine polishing group with diamond particles(1.17 ± 0.33)were better than those of One Gloss group(1.84 ± 1.00)(P < 0.05);The color match and translucency scores of the rubber wheel polishing + fine polishing group with diamond particles(3.00 ± 0.47)and the diamond bur / green stone finishing and smoothing + rubber wheel polishing + fine polishing group with diamond particles(2.47± 3.92)were worse than those of One Gloss group(1.57 ± 0.45)(P < 0.05).Conclusion:1.When ceramic partial veneers were used to restore incisal angle defect of anterior teeth,the esthetic effect of labial edge of the preparation body designed as knife-edge is better than designed as no-prep and slight chamfer edge.2.When ceramic partial veneers were used to restore incisal angle defect of anterior teeth,and if there are obvious steps or overhangs in the labial marginal areas of ceramic partial veneers,as well as poor transitions between the restoration and teeth,diamond burs or stones can be used for smoothing first,and then polishing it,instead of directly polishing it.At the same time,excessive finishing or polishing should be avoided.When there are no obvious steps or overhangs in the labial marginal area of ceramic partial veneers and the transition between the margin of the restoration and the teeth is good,simple polishing is sufficient. |
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