mixed dentition analysis

model analysis in mixed dentition

1. MIXED DENTITION ANALYSIS Preceptor:- Dr.Rakesh Sharma Presented by:- Kumar Adarsh

2. CONTENTS 1.Introduction 2.Classification 3 .Methods of mixed dentition analysis 4. Referenes

3. INTRODUCTION Model analysis is the study of dental casts, which helps to study the occlusion & dentition from all three dimensions & analyze the degree & severity of malocclusion , to derive the diagnosis & plan for treatment.

4. ADVANTAGES They are three dimensional records of the patient’s dentition. Occlusion can be visualized from the lingual aspect. They provide a permanent record of the intermaxillary relationship. Helps to motivate the patients,as they can visualized the treatment progress. They are needed for comparison purposes at the end of treatment & act as a reference for post treatment changes. They serve as reminder for the parent & the patient of the condition present at the start of treatment. In case the patient has to be transferred to another clinician, study model are an important record.

5. DISADVANTAGES Vertical skeletal jaw discrepancy can’t be ascertained from cast. Dental cast simply provide an idea of the relative anteroposterior relationship of the jaws to each other. Wheather the maxilla is retrusive or protrusive can’t be ascertained from casts i.e.anteroposterior status of jaw to skeletal craniofacial complex can’t be determined from study cast. Degree of labial/lingual inclination of incisors observed on cast can be misleading because one tends to judge in relation to the artistic portion of the dental cast base. Ref:-Jacobson A.,Jacobson R.L;Radiographic cephaometry from basics to 3-D imaging.2 nd ed;2-4

6. Mixed dentition period

7. CLASSIFICATION Radiographic Nance analysis,1940 Huckaba’s,1964 NONRADIOGRAPHIC SPACE ANALYSIS Ballard and Willie,1947 Moyer’s, 1973 Tanaka Johnston,1974 COMBINATION OF RADIOGRAPHS & PREDICTION CHARTS Hixon and Old father,1956 Staley kerber-combination,1980

8. AIM OF MIXED DENTITION ANALYSIS To evaluate the amount of space available in the arch for succeeding permanent teeth and necessary occlusal adjustment. Handbook of Orthodontics – Robert E Moyers – 4th edition;235

9. SPACE ANALYSIS Space analysis , using the study casts is valuable in evaluating the likely degree of crowding for a child in the mixed dentition ; and in that case,it must include the prediction of the size of the unerupted permanent teeth.

10. Nance’s mixed dentition analysis (radiographic method),1947 This analysis is similar to arch perimeter analysis of the permanent dentition Armamentarium Dental cast Boley gauge, millimeter ruler Peri -apical radiograph

11. PROCEDURE Actual width of four mandibular incisors measured on the cast. The width of unerupted canine,premolars is measured from the radiograph. In case one of the premolar is rotated,the width of the premolar on the opposite side may be used.

12. The total value indicates the amount of the space needed to accommodate all the permanent teeth anterior to first permanent molar. The space available for the permanent teeth is determined with a brass wire passing over the buccal cusp and incisal edges of teeth from first molar to first molar.

13. Substract 3.4mm(in mandibular arch) and 1.8mm(in maxillary arch)from the total space available to accommodate a decrease in the archlength as a result of the mesial drift(late mesial shift-leeway’s space)of the permanent first molars. Space required - space available = amount of discrepancy

14. ADVANTAGES It results in minimal errors It can be performed with reliability It allows analysis of both arches LIMITATION It is time consuming Complete mouth radiograph is needed.

15. Hukaba’s mixed dentition analysis,( radiographic method)1964 Principle-If we measure an object,which can be seen both in the radiograph as well as on a cast, then we can compensate for the enlargement of the radiographic image. The amount of distortion can be calculated and the correct mesiodistal width of the crown of the unerupted tooth can be calculated by using the formula:-

16. X1/X2=Y1/Y2 X1=width of the unerupted tooth whose width is to be determined X2= width of the unerupted tooth on the radiograph Y1=width of erupted tooth as measured on the cast Y2= width of erupted tooth as measured on a radiograph.

17. Advantage Very easy,practical and relatively accurate method. Not require any prediction table. Can be used in maxillary and mandibular arches. Disadvantage Inherent distortion of radiographic image causes error.

18. MOYER’S MIXED DENTITION ANALYSIS(1973) Basis- high co relation among groups of teeth , thus measuring one group of teeth, prediction of size of other group of teeth can be done. Armamentarium- Dental cast Boley’s guage Probability chart

19. Procedure : Measure the greatest mesiodistal widths of each of four permanent mandibular incisors . The mandibular incisors have been chosen for measuring,since they are erupted into the mouth early in the mixed dentition, are easily measured accurately, and are directly in the midst of most space management problems . The maxillary incisors are not used in any of the predictive procedures, since they show too much variability in size (especially max. lat incisor), and their correlations with other groups of teeth are,of lower predictive value. Therefore, the lower incisors are measured to predict the size of upper as well as lower posterior teeth .

20. Total the M-D widths of mandibular incisors. Using prediction chart for space available in mandibular arch,locate the value closest to the sum of four mandibular incisors. On the study cast, determine and mark the midline of mandibular arch . Total the M-D widths of right mandibular incisors & set the boley’s gauge to this value. Measure from midline to right side. Place one point of the gauge at the midline between the central incisor and let the other end lie along the line of the dental arch on the right side. Mark on the point where the precise point where the distal tip of boley’s gauge touched. Repeat for the left side.

21. Measure the distance between the point marked on the cast to the mesial surface of permanent 1st molar Record that value and calculate the difference Repeat the process on the maxillary arch . Compute the amount of space available. Measure the distance from the point marked on the cast to mesial surface of the 1st molar, and calculate space difference.

22. Advantages It has minimal error. Can be done with equal reliability by the beginner and by an expert. Not time consuming No special equipment required Can be done in mouth as well as on cast Can be used for both arches No radiograph required Handbook of Orthodontics – Robert E Moyers – 4th edition;235

23. Limitations 1. Moyer’s analysis is probability analysis. 2. It does not account for tipping of mandibular incisor either lingually or facially . 3 . Moyers advised caution in using any analysis, as none was able to compensate for the biological variation in individuals during the transition from primary to permanent dentition 4 . Moyers equation does not mention the population group from which they were calculated 5 . Moyer’s method of prediction may have population variations . For one to be sure of the accuracy while using Moyer’s method it may be safer to develop prediction tables for specific populations. Thus Moyer’s method cannot universally be applied.

24. TANAKA JOHNSTON ANALYSIS,1974 Armamentarium Boley guage Study cast The prediction of the size of the unerupted canines and the premolars in contemporary orthodontic population can also be done with the Tanaka Johnston analysis. Tanaka and Johnston conducted a study on 506 orthodontic patients in Cleveland. Ref:-Tanaka MM, lohnston LE: The prediction of the size of the unerupted canines and premolars in a contemporary orthodontic population . J Am Dent Assoc 1974; 88:798.

25. They believed that the Moyer’s equations and the size of his confidence intervals have never been validated on any other samples. Also that the possibility of secular changes during the past 20 years cannot be ruled out. Hence they undertook the study in the Orthodontic Department of Case Western University school of dentistry

26. Tanaka & Johnston prediction values One half of the mesiodistal width of the four lower incisor +10.5mm=estimated width of mandibular canine and premolar in one quadrant. +11.0 mm=estimated width of maxillary canine and premolar in one quadrant. Contemporary Orthodontics – William Proffit – 5th edition;428-29

27. Advantages - • Technique involves simple, easily repeated procedure with minimum material requirement • Prediction chart and radiograph is not required Limitations • Error in predicted size if patients are not from North western European descent.• * John Y. K. Linga ; Ricky W. K. Wong concluded constants for males (upper-11.5; lower-10.5) or females (upper-11.0; lower-10.0) for southern Chinese population

28. HIXON-OLDFATHER PREDICTION METHOD FOR THE MANDIBULAR ARCH (1956)  Iowa Facial Growth Study . 41 children 15 male,26 female) The original equation was primarily obtained from the measurements of the teeth on the left side of the arch of each subject whereas the revised equation was derived from the means of measurements taken from both right and left side teeth in each subject. Armamentarium- • Boley guage • Study cast • Periapical radiograph • Hixon - old father prediction chart Ref:- Hixon EH,OldFather RE ,Estimation of the sizes of the unerupted cuspid and the bicuspid teeth : Angle Orthod : 1958:28:236-240

29. Procedure From the casts, on one side, measure the m-d widths of the permanent mandibular central and lateral incisor. From the periapical radiographs, measure the m-d width of unerupted first and second premolars Total the m-d widths of four(4) teeth. Compare the measured value to estimated tooth size from the Hixon - Oldfather chart. Repeat steps 1 to 3 for the other side of the arch . Advantage- it is very accurate technique Limitation- Can be used only for lower arch. Measured value Estimated tooth size 23mm 18.4mm 24mm 19.0mm 25mm 19.7mm 26mm 20.3mm 27mm 21.0mm 28mm 21.6mm 29mm 22.3mm 30mm 22.9mm

30. Staley and Kerber method,1980 This method uses both IOPA X-rays and measurements on dental casts. A revision of Hixon and Oldfather mixed dentition prediction method (1958) was undertaken by Staley and Kerber on the same group of subjects used originally by Hixon and Oldfather to develop their prediction. These subjects were among those who participated in Iowa Facial Growth Study. Based on equations and computerised data analysis,significantly improved prediction equations were developed . Staley and Kerber in a later study conducted at the Iowa, significantly reduced the standard error of estimate when they generated a revised Hixon and Oldfather prediction equation. The co-efficient of correlation of the revised equation was significantly higher than that of the original equation. Ref.-Staley RN, Kerber PE. A revision of the Hixon and Oldfather mixed-dentition prediction method. Am J Orthod 1980; 78(3): 296-302.

31. A graph was made for clinical use in the prediction of mandibular canine and premolar widths in mixed dentition patients . This prediction graph is accurate to the nearest 0.1mm. Their method requires measurement of the incisors on models/clinically and of mandibular premolars on radiographs .

32. Step by step procedure for analysis 1. Measure and add up widths of mandibular central and lateral incisors on one side 2. Measure widths of unerupted premolars from IOPA radiograph of the same side. 3. Sum of 1+2 4. Use the prediction graph to calculate widths of unerupted canine and premolars.

33. If measurements were available for only one side of the arch , it can be reasonably assumed that the prediction for one side would be very similar to that of the opposite side of the arch. Measurement of severely rotated premolars on radiographs is best avoided. A long-cone periapical radiographic technique should be used in conjunction with this method.

34. The simple computations and the convenient graph make this prediction method suitable for clinical use. The standard error of estimate for the prediction graph is 0.44 mm . All the methods used to predict the widths of unerupted premolars and canines in the mixed-dentition patient are subject to some error. Methods and estimates with minimal error are obviously preferable to those with larger errors. Staley and Kerber method was comparatively more accurate than Hixon and Oldfather . The reasons of improvement were: • Use of a computer, which employed 16 significant digits in its computations. Hixon and Oldfather did not have the use of an electronic computer. • Oldfather’s measurements were taken on one side of the arch only most commonly the left side whereas measurements were taken on both sides of the arch for Staley and Kerber method. • Hixon and Oldfather used a Boley gauge that read to the nearest 0.1 mm, whereas Helios dial calipers read to the nearest 0.05 mm were used in Staley and Kerber method. • Premolars that were rotated on the radiographs were not measured in Staley and Kerber method but were measured by Hixon and Oldfather .

35. Ballard & wylie’s modification,1947 Ballard and Wylie were so concerned about the distortions of the X- ray films that they devised a scheme for estimating the widths of the mandibular canine and the premolars on the basis of the combined widths of the four lower incisors. Using the plaster models of 441 cases, they measured and recorded the widths of all the mandibular teeth including the first molars. On the average, the sum of the four permanent lower incisors were 23.84 +/- 0.08 mm. The average sum of the canine,first and the second premolars turned out to be 21.97 +/- 0.06mm Ref.-Ballard,Murray L and Wylie, Wendell L : Mixed dentition case analysis :Estimating the size of the unerupted permanent teeth : Am Jol Ortho & Oral Surg : 1947 : 33: 754-759

36. Although not particularly high, the co-efficient of correlation of +0.64 seemed sufficiently high to justify a predicton . They modified the equation as Y = 9.41 + 0.527 ( X ) Testing these calculations on 60 cases , Ballard and Wylie came to a conclusion that their method had only 2.6% error as compared to the 10.5% error when using only the X-rays. They do indicate that good X rays should be used and suggest that their method was an adjunct to the Nance’s method.

37. Irwin r herold j,richardson a (1995) They did a review of Methods that have been proposed for mixed dentition analysis , Studies comparing the different methods have shown that the method of Hixon & Oldfather (1958), as refined by Staley & Kerber (1980), is the most accurate . * Mixed dentition analysis forms an integral aspect of orthodontic diagnosis to determine whether the treatment plan is going to involve serial extraction, space maintenance, space gaining or simply periodic observation of the patient. Ref:-Irwin R, Herold J, Richardson A. Mixed dentition analysis: a review of methods and their accuracy. IJPD 1995;5:137-142

38. Sushma Sonawane,Asha Bettigiri,Vivek Soni,2008 Examine and compare the accuracy of the Moyers and Tanaka & Johnston mixed dentition analyses and to evaluate its applicability to Indian Marathi population. Developed regression analysis- Y = a + b (X) where , X = independent variable (mandibular incisors measurements) Y = dependent variable (sum of canine and premolars ). For mandibular teeth- Y = 10.830 + 0.563 ( X) For maxillary teeth- Y = 12.143 + 0.481 (X) Ref:-Sonawane S, Bettigiri A, Soni V. Comparison of two non-radiographic techniques of mixed dentition analysis and evaluation of their applicability for marathi population; Scientific Journal 2008;vol 2.

39. They concluded that a ) Both Tanaka Johnson and moyers have comparable standard errors of estimate,thus their accuracy is fairly comparable . b ) Moyers chart at 50% confidence level gives more realistic estimate of width of unerupted canine and premolars as compared to 75% confidence level for Marathi population . c ) Sugessted the use of newly developed regression equations is suggested.

40. None of the Mixed Dentition Analyses are as precise as one might like, and all must be used with judgment and knowledge of development. Hixon and Oldfather : most accurate Tanaka and johnston : most practical Radiographic Radiographic method: for population other method: for population other than Caucasians Inaccuracy in radiographic tooth size measurements is not the dentist's fault. It occurs because the developing teeth are not always placed exactly at right angles to the central ray;therefore , the radiographic image of the tooth, when slightly rotated or tipped, is significantly larger than the actual size of the tooth. conclusion

41. THANK YOU

42. 1) Mathewson R, Primosch R. Fundamentals of pediatric dentistry.3rd ed;30-33 2 ) Marwah N. Textbook of pediatric dentistry. Jaypee . 299-307 3 ) Irwin R, Herold J, Richardson A. Mixed dentition analysis: a review of methods and their accuracy. IJPD 1995;5:137-142 4 ) Orthodontics-the art and science- S.I. Bhalajhi – III edition 5 ) Textbook of Pedodontics-Shoba tandon I edition 6 ) Handbook of Orthodontics – Robert E Moyers – 4th edition 7 ) Contemporary Orthodontics – William Proffit – 5th edition

43. 8) Ballard,Murray L and Wylie, Wendell L : Mixed dentition case analysis :Estimating the size of the unerupted permanent teeth : Am Jol Ortho & Oral Surg : 1947 : 33: 754-759 10)Text book of orthodontics- Samire E Bishara 11) Hixon EH,OldFather RE ,Estimation of the sizes of the unerupted cuspid and the bicuspid teeth : Ang Ortho : 1958:28:236-240 12 ) Buwembo W, Luboga S.Moyer’s method of mixed dentition analysis: a meta- analysis.African Health Sciences2004;4: 63-66 13 ) Sonawane S, Bettigiri A, Soni V. Comparison of two non-radiographic techniques of mixed dentition analysis and evaluation of their applicability for marathi population; Scientific Journal 2008;vol 2 . 14 ) Textbook of Orthodontics- Gurkeerat Singh – 2nd edition