Epidemiological Investigation and Mechanical Experiment of Deciduous Tooth Precrown in 2-6 Year Old Children in Hangzhou City
Objective To investigate the regularities of caries distribution in the primary dentition of children in Hangzhou,China.To measure the compressive failure resistance of primary mandibular second molar crowns from three different manufacturers-resin preformed crown,zirconia preformed crown and glass preformed crown.Methods A total of 1 000 children aged 2-6 years were selected from the children's Stomatology department in the west of Hangzhou Stomatology Hospital.Resin,zirconia and glass-ceramic deciduous teeth were preformed on the resin model of mandibular second deciduous molar with resin adhesive respectively.The compressive strength test was carried out on the universal material test machine,and the compressive destructive force value of the specimen was recorded.SPSS 24.0 statistical analysis software was used for statistical analysis of the data.Results Right mandibular second primary molars are at highest risk of caries,followed by left.Primary molars suffer from higher caries than primary anterior teeth.The distribution of caries concentrated on the occlusal surface,followed by the mesial and distal proximal caries,and lingue caries have the lowest rate.3 group of compressive failure resistance respectively:resin group(694.85±292.20)N,zirconia group(537.31±152.03)N,glass group(613.73±303.92)N.The comparison between any two of them has no statistical significance(P＞0.05).Conclusion The primary tooth caries distribution has specificity in tooth surface.Primary molars have a high rate of caries,and there are many caries surfaces.The forces required to fracture the resin crowns were greater than the glass porcelain and zirconia crowns.
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