تخمين اندازه دندان هاي كانين و پرموله هاي رويش نيافته از روي دندان هاي ثناياي فك پايين در جمعيت مورد مطالعه در تبريز

estimation of the size of unerupted canine and premolars from the mandibular incisors teeth in Tabriz

Background & Aim: One of the important aspects of diagnosis in the mixed dentition is the determination of the relationship between the tooth size and available space. The determination of this relationship in the mixed dentition requires an accurate prediction of the mesiodistal width of the unerupted permanent canines and premolars. Three approaches have been used to estimate the mesiodistal crown width of these teeth. From these approaches, the Tanaka-Johnston prediction equation is widely used today. The purposes of this investigation are to examine the applicability of the Tanaka-Johnston method at the 50% and 75% levels in an Iranian population studied. Methods & Materials: The study type was cross - sectional, in which, dental casts of 53 male and 60 female subjects were estimated. Results: The findings of this study indicate that Tanaka-Johnston method at both 50% and 75% levels overestimate the teeth size, but the difference between predicted size and actual size at the 50% level is less than that for 75% level. For this population new linear regression equation were derived, as the following: Maxillary: Y = 9.54 + 0.52X Mandibular: Y = 8.77 + 0.54X The results of this investigation indicated that commonly used Tanaka-Johnston equation at 75% level in Iranian sample in not accurate. Conclusion: This result is like other similar studies. It appears that ethnic origin is the most important factor in the results derived. Further studies with a larger sample size is indicated to confirm these findings.