Model analysis.pptx
- 1. MODEL ANALYSIS SUBMITTED BY GOPIKA SAJEEV FINALYEAR PART II
- 2. INTRODUCTION • Model analysis is one of the most essential diagnostic aids to visualize the patient’s occlusion from all aspects and also helps in making necessary measurements of teeth, dental arches, basal bone to carry out space analysis. • Model analysis can be defined as the study of maxillary and mandibular arches in all the three planes of space (sagittal, vertical, transverse) and is a valuable tool in orthodontic diagnosis and treatment planning.
- 4. PONT’S ANALYSIS Uses • Determining whether the dental arch is narrow or is normal. • Determining the need for lateral arch expansion. • Determining how much expansion is possible at the premolar and molar region.
- 5. LINDER HARTH INDEX • This analysis is similar to Pont’s analysis except that a new formula was used to determine the calculated premolar and molar values. Premolar value was calculated by = SI × 100/ 85 • Molar value was calculated by = SI × 100/ 64
- 6. KORKHAUSANALYSIS • This analysis is also similar to Pont’s analysis but he used Linder Harth’s formula to determine the ideal arch width in the premolar and molar region.In addition he also uses the measurements made from the midpoint of the interpremolar line to a point between the two maxillary incisors. • Korkhaus devised an instrument “The Orthometer” which helps to measure the ideal arch width in premolar and molar region and also to know the perpendicular distance from the interpremolar line to the patient in between the 2 incisors for a given sum of mesiodistal widths of the maxillary incisors. Inference • If there is an increase in the perpendicular measurement than ideal then the anterior are proclined and if it is less than they are retroclined.
- 7. ARCH PERIMETERANALYSIS This is an upper arch analysis.This analysis helps us to find out the difference between the basal bone and the tooth material, i.e. it helps in determining the extent of discrepancy.
- 8. Inference By comparing the tooth material and arch length required we can obtain the extent of arch length discrepancy • If tooth material more than space available – crowding • If tooth material less than space available – spacing • If it is between 0 and 2.5 mm → non-extraction • If it is between 2.5 and 5 mm → 2nd premolars extraction • If it is more than 5 mm → 1st premolar extraction.
- 9. CAREY’S ANALYSIS • This is same as arch perimeter analysis done for maxillary arch except that this is done on mandibular arch. • The same steps as in arch perimeter analysis must be followed to determine: Tooth material(space required) Arch perimeter(space available) Arch length discrepancy.
- 10. BOLTON’SANALYSIS • Also called as Bolton’s tooth size ratio analysis. • According to Bolton, a ratio exists between the mesiodistal widths of maxillary and mandibular teeth. • He studied the interarch effects of discrepancies in tooth size to devise a procedure for determining the ratio of total mandibular versus total maxillary tooth size versus maxillary anterior teeth size.
- 12. PECK AND PECK RATIO • This done on the lower arch. • Persons with ideal incisal arrangement had smaller mesiodistal width and comparatively larger labiolingual width than in persons with incisal crowding
- 13. • Meanvalue for mandibular central incisor=88 to92percent. • Mean value for mandibular lateral incisor = 90 to 95 percent. Inference • If the value for a given case is more than the mean value then • mesiodistal width of the tooth is more than the labiolingual • width and hence proximal stripping is indicated in such cases.
- 14. HUCKABA’SANALYSIS • He used both study casts and radiographs for determining the width of unerupted tooth. • To compensate for enlargement of radiographic images measure an object that can be seen both in radiograph and on the cast such as primary molar tooth. Accuracy of this method of determining the width of the unerupted tooth is fair to good, depending upon the quality of the radiographs and their position in the arch. • This technique can be used both in maxillary and mandibular arches in all ethnic groups. • Then a simple proportional relationship can then be established as follows: Actual width of primary molar (X1) /Apparent width of primary molar (X2) = Actual width of unerupted premolar (Y1) /Apparent width of unerupted premolar (Y2) Y1 = X1 ×Y2 /X2
- 15. MOYER’S MIXED DENTITIONANALYSIS • There is high co-relation between sizes of different teeth in same individual, thus making it possible to predict the size of unerupted tooth by looking at the teeth present in oral cavity.
- 16. Inference If the predicted value is greater than available arch length crowding of teeth can be expected.
- 18. • Available arch length = total arch length – sum of incisors + 2 predicted width +value : space surplus –value : space deficit • Tanaka and Johnston prediction values One half of the mesio-distal width of four lower incisors + 10.5 mm =estimated width of mandibular canine and premolar in one quadrant. One half of the mesio-distal width of four lower incisors + 11.0 mm =estimated width of maxillary canine and premolar in one quadrant. Inference • If the result is positive, there is more space available in the arch than is needed for the unerupted teeth. • If the result is negative, the unerupted teeth require more space than is available to erupt into ideal alignment.
- 19. HIXON AND OLDFATHER’S METHOD
- 21. CONCLUSION • Model analysis is a valuable tool in orthodontic diagnosis and treatment planning and the main advantage of model analysis over other aids is that model analysis offers a three-dimensional view of the same. • It is an important pre-treatment record taken prior to use of fixed or removable orthodontic appliances
- 22. THANKYOU