Primary Study On The Prediction Method Of Dental-arch Development Of The Children In Northern Fujian

Objective：The aim of the present study was to determine the applicability of the Moyersprediction tables and Tanaka-Johnson prediction equations in the prediction ofun-erupted canines and premolars in a population of North Fujian province, China.Also, new regression equations are presented to predict the width of the un-eruptedcanines and premolars based on the sum of the mesiodistal width of the lower incisors.In addition, the mesiodistal crown diameters of the deciduous incisors and theirpermanent successors were measured and correlation analyses were calculated.Method：For the first cross-sectional study, a total of120dental casts (64boys and56girls ranging in age from12to15years) were recruited from a population of NorthFujian province, China. The greatest mesiodistal widths of all the teeth weremeasured using3DSS technology and Geomagic9.0software. All the data werecompared with Moyers prediction tables and Tanaka-Johnson prediction equationsusing independent t-test and paired sample t-test.The second study is a longitudinal study, in which3DSS technology was used toobtain the measurements precisely from60pairs of randomly selected serial dentalcasts (30males and females respectively). Descriptive statistics was used for theanalysis of the data. Size relations of the primary incisors and correspondingpermanent successors were studied, and the effect of sexual dimorphism on themesiodistal tooth sizes as well as on the increment of tooth mass was statisticallyanalyzedResult：Tanaka-Johnston equations and Moyers prediction tables revealed a significantdifference with the mesiodistal dental width of northern Fujian population. Also, therewas a significant difference between the mesiodistal width of the teeth of males andfemales. So, new regression equations based on the sum of the lower incisors were introduced for different jaws and sexes in the first study. Sexual dimorphism is likelyto be an important variable in tooth size analysis. Correlation analyses showed somecorrelation between the primary incisors and their permanent successors.Conclusion：1. Moyers prediction tables and Tanaka-Johnston equations are not suitable inpredicting the width of un-erupted canines and premolars of northern Fujianpopulation.2. The regression equations calculated for the width of un-erupted canines andpremolars including sex and arch were as follows: Maxilla Y=0.480X+11.539Male Mandible Y=0.531X+9.456Maxilla Y=0.410X+12.545Female Mandible Y=0.511X+9.378Y represents the mesiodistal crown width of the un-erupted canines and premolars.X represents the mesiodistal crown width of the four lower incisors.3. The results obtained in the longitudinal study could be of help in pediatric dentalpractice for space assessment. Results are also of importance to anthropologists andmay be used as a basis for future studies.