Original Article APPLICABILITY OF MOYER S AND TANAKA-JOHNSTON MIXED DENTITION ANALYSIS IN SCHOOL CHILDREN OF SRI GANGANAGAR DISTRICT (RAJASTHAN) A PILOT STUDY Thakur H, Jonathan PT Postgraduate student, Maharaja Ganga Singh Dental College and Research Centre, Sriganganagar, Rajasthan. ABSTRACT Introduction: Mixed dentition analysis enables the clinician to identify tooth size-arch length discrepancy and, according to the results obtained, proposes different treatment approaches such as: serial extraction, guidance of eruption, space maintenance, space regaining or just periodic observation of the patient. Of all the mixed dentition analysis, the methods that are used most commonly are the Moyers probability charts and Tanaka Johnston equation. These methods are based on the data obtained from an unspecified number of North American white children. Therefore the accuracy of these prediction methods could possibly be in question when applied to a population of different ethnic origin. Materials and Methods: The dental study models of 60 subjects (30 males and 30 females) including children studying in different schools of Sri- Ganganagar city and from Out Patient Department (OPD) of the college in the age group of 12 16 years were taken. Measurements were made onto those casts of the sum of mandibular anterior mesiodistal widths and the sum of mesiodistal widths of erupted canines and premolars. The values obtained were subjected to statistical analysis.results: The correlation co-efficient between the sum of mandibular incisors and the sum of canine and premolars were 0.42 (for upper arch) and 0.53 (for lower arch) in male subjects, and 0.51 and 0.61 respectively, in female subjects. Conclusion: The results of the present study led to the following conclusion: Both Moyers (75%) & Tanaka and Johnston prediction methods were not as accurate when applied to sample of Sri Ganganagar population since they tend to overestimate the actual measurements. Corrseponding Author:Dr. Himani Thakur.Postgraduate student, Maharaja Ganga Singh Dental College and Research Centre, Sriganganagar, Rajasthan How to cite: Thakur H, Jonathan PT. Applicability Of Moyer s And Tanaka-Johnston Mixed Dentition Analysis In School Children of Sri Ganganagar District (Rajasthan) A Pilot Study. IDA Lud J le Dent 2017;1(3):17-23 IDA Ludhiana s Journal ledentistryvol.1 issue 3 2017 17
INTRODUCTION The transition from the primary to the permanent dentition i.e. the mixed dentition period (6 th 12 th year of life) is the most dynamic phase in terms of changes in occlusion and final outcome of the dentoskeletal relationship. It is believed that a large number of cases of malocclusion start during this stage. Many of these developing malocclusions may be reduced in severity or even eliminated entirely by timely management. 1 In planning the management of such cases, a correct diagnosis is the first step, and mixed dentition analysis is considered a fundamental step to make a good diagnosis. The mixed dentition analysis enables the identification of a tooth size-arch length discrepancy and, according to the results obtained, proposes different treatment approaches such as: serial extraction, guidance of eruption, space maintenance, space regaining or just periodic observation of the patient. 2 The determination of tooth size-arch length discrepancy in the mixed dentition requires an accurate prediction of the mesiodistal width of the unerupted permanent teeth. Several methods have been developed for estimating the mesiodistal widths of unerupted teeth: I. II. III. Direct measurements of unerupted tooth size on the radiographs, as recommended by Nance HN 3 Calculations from prediction equations and tables, as reported by Moyers 4 and Tanaka and Johnston 5 Combination of radiographic measurements and prediction tables, as recommended by Hixon and Oldfather 6 and Staley et al 7 Of all the mixeddentition analysis, the methods that are used most commonly are the Moyers probability charts and TanakaJohnston equation. These methods are based on the data obtained from an unspecified number of North American white children. 5 So it is reasonable to question their use in other populations because tooth sizes vary significantly between andwithin different racial groups. 8.9 Since space evaluation is significantly important in many areas of mixed dentition treatment and major treatment decisions are based on differences involving a very few millimeters, it would be to the advantage of the dentist to use as accurate a method of prediction as possible. Thus, the present study was planned to evaluate the applicability of Moyer s & Tanaka-Johnston mixed dentition analysis in school going children of age group (12-16) years in Sri Ganganagar district (Rajasthan) and to determine the correlation coefficients and derive a new prediction equation for Sriganganagar population, if required. MATERIAL AND METHODS The dental study models of 60 subjects (30 males and 30 females) which included children studying in different schools of Sri- Ganganagar city and from Out Patient Department (OPD) of Paediatric and Preventive Dentistry, Maharaja Ganga Singh Dental College and Research Centre, Sri Ganganagar, Rajasthan were collected. The study was approved by institutional ethical committee. Informed consent was obtained from the parents. Inclusion criteria for sample selection were: All the subjects should be the natives of Sri Ganganagar district, Rajasthan, 12-16 years old, with Angle s Class I molar relation. All the permanent teeth to be examined i.e. mandibular central IDA Ludhiana s Journal ledentistryvol.1 issue 3 2017 18
incisors and lateral incisors, maxillary and mandibular canines and premolars should be present and fully erupted, with no evidence of proximal dental caries, restorations, fractures, tooth wear and dental anomalies. Exclusion criteria for sample selection included: Subjects with moderate to severe malocclusion. Those undergoing or had undergone an orthodontic treatment. Subjects with clinical abnormalities affecting the jaws, congenitally missing or impacted permanent teeth. Alginate (Plastalgin, Septodont, USA) impressions were made for both maxillary and mandibular arches. The dental impression was then poured immediately with a proper mix of dental stone. The models were checked for any distortions or voids. The teeth were measured using a Digital vernier calliper. The largest distance between the contact points of the four mandibular incisors and the maxillary and mandibular canines and premolars was measured with the digital vernier caliper. The Moyers and Tanaka-Johnston s methods were used to predict the sizes of the unerupted mandibular permanent canine and two premolars. Data were analyzed using IBM SPSS Statistics Windows version 20.0 (Armonk, NewYork: IBM Corp). Descriptive statistics including mean, standard deviation and range were calculated and paired t-test was done to compare the mean of actual and predicted mesio-distal dimensions of canines and premolars of both maxillary and mandibular arches.the new regression equations were determined using the lower four permanent incisors as predictors for the sum of the widths of lower permanent canine and premolars. The correlation coefficient was also obtained. RESULTS Pearson's coefficients of correlation of mesiodistal dimensions of mandibular incisors with canine & premolars 0.42 (for upper arch) and 0.53 (for lower arch) in male subjects, and 0.51 and 0.61 respectively, in female subjects (Table 1). Comparison of difference in means of actual dimensions of canine & premolars and values showed a statistically significant difference between the predicted Tanaka- Johnston equation and actual values (p<0.01) as shown in Table 2. Moyers (75%) also showed statistically significant difference (Table 3) between the predicted and actual values (p<0.01). Both Tanaka Johnston method and Moyers (75%) overestimated the measured values for both males and females. Regression coefficients and new prediction equations for mesiodistal dimensions of canine & premolars in males and females are depicted in Table 4. Table 1:-Determination of correlation coefficients for maxilla and mandible in both males and females. IDA Ludhiana s Journal ledentistryvol.1 issue 3 2017 19
Table 3:- The comparison of predicted values based on methods of Moyers & Tanaka and Johnston in male subjects. Table 4:-The comparison of predicted values based on methods of Moyers & Tanaka and Johnston in female subjects. Table 5:- Correlation coefficients of maxilla and mandible in males and females and corresponding regression equations derived from both male and female sexes. IDA Ludhiana s Journal ledentistryvol.1 issue 3 2017 20
DISCUSSION Since Pedodontists and Orthodontists treat children of various racial and ethnic mixes, it will be beneficial if they use mixed dentition prediction aids developed for specific population groups, such as those proposed in this study for Sri Ganganagar population.the age range between 12-16 years was chosen, as these children have minimal dental attrition and the teeth to be measured would have been erupted into the oral cavity in both the dental arches.factors that affect tooth size are categorized into extrinsic as well as intrinsic. The intrinsic factors include heredity, race and sex. The extrinsic factors being caries, attrition, measuring methods of the mesiodistal tooth size which include method of cast preparation, material used for cast preparation, instrument used for measurement of tooth size, and method of analysis of error. 10 The present analysis showed a positive correlation of 0.42 for maxilla and 0.53 for mandible for males and 0.51 for maxilla and 0.61 for mandible in case of femalesbetween sum of mandibular incisors with actual value of sum of canine and premolars. The correlation coefficients obtained in this study are similar to those of several other studies; Hixon and Oldfather 6 (0.69), Tanaka and Johnston 5 (0.65). This implicates that 60 to 70% of the polygenes that determine tooth size are shared between the mandibular incisors and the canines and the premolars. 6 This common genetic code gives theoretical justification for the estimation of unerupted canine & premolar widths based on the mesio-distal dimensions of already erupted mandibular incisors, even though these teeth belong to different morphologic classes. The results of this study indicated that the currently popular Moyers analysis (75%) and Tanaka and Johnston prediction equations were not sufficiently accurate to predict the mesiodistal widths of unerupted canines and premolars in Sri Ganganagar population. With the help of the data obtained, we have formulated new regression equations separately for males and females to be used to predict the permanent tooth dimension. We feel these would be more appropriate than both Moyers and Tanaka Johnston mixed dentition analysis for the population of Sri Ganganagar. Male: Maxilla - y = 9.06 + 0.38 (x) Mandible - y = 8.35 + 0.33 (x) Female: Maxilla - y = 9.79 + 0.32 (x) Mandible - y = 7.98 + 0.31 (x) where y is the predicted mesiodistal width of unerupted canines and premolars and x is the measured width of mandibular central and lateral incisors. CONCLUSION IDA Ludhiana s Journal ledentistryvol.1 issue 3 2017 21
The results of the present study led to the following conclusion: Both Moyers (75%) & Tanaka and Johnston prediction methods were not as accurate when applied to sample of Sri Ganganagar population since they tend to overestimate the actual measurements. So, new regression equations for Sri Ganganagar population were formulated for males and females separately. The newly formed regression equations provided more precise results. Further studies on a larger population are recommended to get a more accurate result. REFERENCES 1. Lee-Chan S, Jacobson BN, Chwa KH, Jacobson RS.Mixed dentition analysis for Asian-Americans. Am J OrthodDentofacialOrthop 1998;113:293-9. 2. Bishara, SE, Staley RN. Mixed-dentition mandibular arch length analysis: A stepby-step approach using the revised Hixon-Oldfather prediction method. Am J Orthod.1984;86:130-35. 3. Nance HN. The limitations of orthodontic treatment. Mixed dentition: diagnosis and treatment. Am J Orthod Oral Surg. 1947 Apr; 33(4): 177-223. 4. Moyers RE. Analysis of dentition and occlusion. In: Moyers RE editor. Handbook of orthodontics. 4th ed. Conflict of Interest:NoneSource of Support: NiL Chicago: Year Book Medical Publishers; 1988:p. 235-40. 5. Tanaka MM, Johnston LE. The prediction of the sizes of unerupted canines and premolars in a contemporary orthodontic population. J Am Dent Assoc. 1974;88:798-801. 6. Hixon EH, Oldfather RE. Estimation of the sizes of uneruptedcuspids and bicuspids. Angle Orthod.1958;28:236-40. 7. Staley RN, O Gorman TW, Hoag JF, Shelly TH. Prediction of the widths of unerupted canines and premolars. Journal of the American Dental Association 1984; 108: 185 190. 8. Schirmer UR, Wiltshire WA. Orthodontic probability tables for black patients of African descent: mixed dentition analysis. Am J OrthodDentofacialOrthop 1997;112:545-51. 9. Bishara SE, Jakobsen JR, Abdallah EM, Fernandez Garcia A. Comparisons of mesiodistal and buccolingual crown dimensions of the permanent teeth in three populations from Egypt, Mexico, and the United States. American Journal of Orthodontics and Dentofacial Orthopedics 1989; 96: 416 422. 10. Hambire CU, Sujan S. Evaluation of validity of Tanaka-Johnston analysis in Mumbai school children. ContempClin Dent 2015;6:337-40. This work is licensed under a Creative Commons Attribution 4.0 International License IDA Ludhiana s Journal ledentistryvol.1 issue 3 2017 22
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