IOSR Journal of Dental and Medical Sciences (IOSR-JDMS) e-ISSN: 2279-0853, p-ISSN: 2279-0861.Volume 16, Issue 1 Ver. VII (January. 2017), PP 68-73 www.iosrjournals.org DOI: 10.9790/0853-1601076873 www.iosrjournals.org 68 | Page Comparison And Correlation of Radiographic And Non Radiographic Methods of mixed Dentition Space Analysis With The Formulation of Linear Regression Equation In Children of Mandi District, Himachal Pradesh Dr. Haritima Kahol 1 Dr. Vinay Bal Singh Thakur 2 , Dr. Kanika Gupta 3 , Dr. Pallavi Mishra 4 1 MDS in Pediatric and Preventive Dentistry, Sundernagar, District Mandi, Himachal Pradesh University, India 2 Assistant Professor, Department Of Pediatric And Preventive Dentistry, Himachal Dental College, Sundernagar, District Mandi, Himachal Pradesh University, India 3 Post graduate student, Department of Pediatric and Preventive dentistry, Himachal Dental college, Sundernagar, District Mandi, Himachal Pradesh University, India 4 House surgeon, Himachal dental college, Sundernagar, District Mandi, Himachal Pradesh University, India Abstract: Introduction: Predicting the size of unerupted teeth during the mixed dentition period is a critical factor in managing the developing occlusion. The Nance radiographic method, Moyers mixed dentition space analysis and Johnston Tanaka method are among the most commonly used in clinical practice for detecting tooth size- arch length discrepancies. In view of reported secular trends, racial, and sex differences in tooth sizes, the purposes of this study were to compare and correlate the radiographic and non radiographic mixed dentition space analysis in children of Mandi district, Himachal Pradesh and to formulate a regression equation using the best variable predictors. Method: Odontometric data were collected from 52 male and 48 female subjects of Himachal descent, aging from 8-11 years who had fully erupted mandibular permanent incisors and first molar and unerupted permanent canines and premolars. The measurements of mesiodistal crown widths were made with Vernier scale digital calipers. The odontometric values obtained were then subjected to statistical and linear regression analysis. Results: All tooth groups showed no significant differences (P>0.001) between mesiodistal widths of male and female subjects. Very high correlation was found between the two non radiographic methods i.e. Moyer’s and Johnston –Tanaka method with their r values of 0.990. Correlation of Nance radiographic method with Moyer’s and Johnston Tanaka method was fair showing r values of 0.661 and 0.673 respectively. Conclusion: Estimation of tooth width in early mixed dentition is best made by means of radiographs of the yet unerupted teeth. The non radiographic methods as given by Moyers and Johnston Tanaka give reasonable approximation for prediction width of crown width when it is impossible to obtain satisfactory image. Keywords: Arch length discrepancies, Mixed dentition analysis, Radiographic methods, Non radiographic methods I. Introduction The early mixed dentition period of occlusion, which house both primary and permanent teeth, is much more prone to localized factors which trigger the development of severe malocclusion if left undetected. 1 This period will show crowding in the mandible or maxilla or both the arches, thus early assessment is needed in this period. Presence of maximum orthodontic problems in this particular period is due to the inadequacy of space for erupting permanent teeth. The mixed dentition space analysis helps in early orthodontic evaluation and treatment planning 2 . This type of analysis is a fundamental part of early orthodontic assessment and helps in determining any tooth size-arch length discrepancy. If discrepancy is present, it forms a useful diagnostic aid in determining whether the treatment plan is going to involve serial extraction, guidance to eruption, space maintenance, space regaining or just periodic observation of patient 3 . The dental literature is replete with investigations focusing on the comparative accuracy, reliability, and reproducibility of various mixed dentition space analysis techniques. G. V Black 4 in 1897 attempted to predict the mesiodistal widths of unerupted teeth based on tables of average mesiodistal widths of teeth. Classically mixed dentition analysis techniques rely on one of the following methods: