Studies On The Application Of Haavikko’s Method In Eatimation Of Dental Age In Nanjing Children

Objective:To assess the applicability of Haavikko method in estimating the dental age of Nanjing children, investigate the relationship between dental age and chronological age, and to provide a reference for its using in Chinese children. To find the relationship between the dental age calculated by teeth in the left mandibular quadrant and dental age calculated by all teeth, and to offer advantage for clinic. To investigate the delay of dental development in hypodontia, and to determine whether the severity of the hypodontia had an effect on magnitude of delay.To investigate the relationship of dental age between health children and children who has periradicular lesions of primary teeth, and to determine whether the severity of the infection had an effect on permanent dental germ of delay.Methods:A total of629dental panoramic radiographs(392boys and237girls) of children in Nanjing were collected for the study on the basis of predetermined inclusion and exclusion criteria.All permanent mandibular teeth on the left side of the radiograph(except for the third molars) were assessed,and the stages of development of these teeth were recorded according to Haavikko method. Paired t-test was performed between the chronological age and dental age which was scored by Haavikko method.A single-factor model was used to show the relationship between chronological age and dental age of Nanjing children. The difference between dental age of children with hypodontia and dental age of control group was tested using paired t-test. The correlation between the difference of dental age and chronological age and severity of hypodontia was investigated using Spearman correlation test. The difference between dental age of children with periradicular lesions of primary teeth and dental age of control group was tested using paired t-test, and repeat the test based on the severity of the infection which had an effect on permanent dental germResults:A statistically significant difference was found between chronological age and dental age (P<0.01). Dental age scored by Haavikko method showed an underestimate of0.6years and1.0years in males and females. We set up the mathematical model between dental age and chronological age, then got the curve-fitting equation.Dental age of hypodontia children was less than dental age of control group by0.44years on average (P<0.05),and was0.92years in the oligodontia group.In the hypodontia group, the related coefficient between the difference of dental age and the chronological age and severity of hypodontia was-0.220.No significant different in dental age was found between primary teeth with periradicular lesions and control group. Dental age of single permanent teeth grem showed a significant delay by0.59years. Conclusions:The curve-fitting equation can be used to assess chronological age of Nanjing children, because it shows no statistically significant difference between natural and dental age by using the equation.A significant delay of development of residual teeth in children with hypodontia was found compared to the control group. A significant association was found between dental severity of the hypodontia and magnitude of delay.A significant delay of development of primary teeth with periradicular lesions was found compared to the control group by0.59years on average (P<0.05).