Diese Präsentation wurde erfolgreich gemeldet.
Wir verwenden Ihre LinkedIn Profilangaben und Informationen zu Ihren Aktivitäten, um Anzeigen zu personalisieren und Ihnen relevantere Inhalte anzuzeigen. Sie können Ihre Anzeigeneinstellungen jederzeit ändern.
MODEL ANALYSIS
MODEL ANALYSIS
Submitted By :-
Dibya Falgoon Sarkar
North Bengal Dental College & Hospital
INTRODUCTION
• Model analysis is one of the
essential diagnostic aids in
orthodontics.
• The study model provides a three
...
REQUSITES OF STUDY MODELS
• Should accurately reproduce all the teeth
and soft tissues without any distortion.
• Should be...
PARTS OF A STUDY MODEL
• Anatomic PortionAnatomic Portion - Consists
of the actual impressions of
the dental arch & its
su...
According to ABO (1990) Guidelines
Lateral view of the study model
1.Base of the maxillary
cast is trimmed parallel
to the...
Maxillary occlusal view of study model
Mandibular occlusal view of
study model
REQUIREMENTS TO DO MODEL
ANALYSIS
• Well prepared study models
• Vernier calipers
• Divider
• Ruler
• 0.033” Soft Brass wi...
CLASSIFICATION
PERMANENT DENTITION
MODEL ANALYSIS
MIXED DENTITION MODEL
ANALYSIS
Arch perimeter analysis Moyer’s Mixed den...
PONT’S ANALYSIS
• Pont in 1909, proposed a method of determining the ideal
dental arch width in premolar and first molar a...
PONT’S ANALYSIS HELPS
IN
• Determining whether the dental arch is
narrow or is normal in the premolar and
molar region for...
ANALYSIS
• DETERMINATION OF SUM OF INCISORS (SI)
• DETERMINATION OF MEASURED
PREMOLAR VALUE (MPV)
• DETERMINATION OF MEASU...
• CALCULATED PREMOLAR VALUE (CPV): or the
expected arch width in the premolar region is determined
by:
CPV = SI X 100
80
•...
INFERENCE
•If the measured value is less than the
calculated value, then the arch is narrow for
the given sum of incisors ...
DRAWBACKS
• Maxillary laterals are the teeth most
commonly missing from the oral cavity.
• Peg-shaped laterals can be seen...
LINDER HARTH ANALYSIS
• Linder Harth proposed an index very similar to
that of Pont’s analysis.
• He made variation in the...
KORKHAUS ANALYSIS
• This analysis is similar
to Pont’s analysis.
• Only difference is that it make
use of Linder Harth’s f...
• According to Korkhaus for a given width
of the upper incisors a specific value of the
perpendicular distance between the...
Korkhaus’ Measurements
ARCH PERIMETER
ANALYSIS
• Many malocclusions occur due to discrepancy
between arch length & tooth material.
• It is done i...
PROCEDURE
• DETERMINATION OF SPACE REQUIRED:
• measure the mesiodistal dimension of all the teeth mesial to the
first mola...
• In case of proclined incisors, pass the brass
wire in the cingulum region, and if the
anterior teeth are retroclined, pa...
DETERMINATION OF THE DISCREPANCY
•The difference between the space required
and space available gives the arch
discrepancy...
INTERPRETATION OF ARCH
PERIMETER ANALYSIS
ARCH LENGTH DISCREPANCY INFERENCE
0 to 2.5 mm
Proximal stripping can be carried ...
CAREY’S ANALYSIS
• The arch length-tooth material discrepancy
is the main cause for most malocclusions.
• This discrepancy...
INTERPRETATION OF
CAREY’S ANALYSIS
ARCH LENGTH DISCREPANCY INFERENCE
0 to 2.5 mm
Proximal stripping can be carried out
to ...
ASHLEY HOWE ANALYSIS
• Ashley Howe considered the crowding of
teeth to be the result of deficiency in arch
width rather th...
ANALYSIS
• DETERMINATION OF TOOTH MATERIAL (TTM): mesodistal
width of all the teeth anterior to the permanent second molar...
INFERENCE I
• The PMBAW and PMD are compared.
• If the PMBAW is greater than the PWD,
then it is indicated that arch expan...
INFERENCE II
• According to Howe, to achieve a normal
occlusion with a full complement of teeth,
the basal arch width at t...
INFERENCE
PMBAW % CONCLUSION
37% or less It indicates a need for extraction
37-44% Borderline case
44% or more
Possibly no...
BOLTON’S ANALYSIS
• Wayne Bolton considered the ratio of the tooth material
of the maxillary arch to the mandibular arch i...
Measurements
• Sum of maxillary 12
• Sum of mandibular 12
• Sum of maxillary 6
• Sum of mandibular 6
• Overall ratio
• Ant...
• Overall Ratio = Sum of mandibular 12 *100
Sum of maxillary 12
• For establishing ideal overjet & overbite overall ratio ...
• The sum of M-D widths of the mandibular
anteriors to the M-D width of the max.
anteriors should be 77.2%
• The anterior ...
Disadvanatages of Bolton’s Analysis
• Does not take into account the sexual
dimorphism in the maxillary canine
widths.
• S...
MIXED DENTITION
ANALYSIS
AIM
• The purpose of mixed dentition analysis is to
evaluate the amount of space available in the
arch for succeeding perm...
HUCKABA’S MIXED DENTITION
ANALYSIS (RADIOGRAPHIC METHOD)
• This analysis makes use of a radiograph
and study cast to deter...
PRINCIPLE
• It is based on the principle that if we measure an object,
which can be seen both in radiograph as well as on ...
• SPACE AVAILABLE:
the arch is divided into
segments which are
approximately straight
lines. The dimensions in
each of the...
• It is based on the premise that there is a reasonably good
correlation b/w the size of erupted permanent incisors and
th...
PROCEDURE
• STEP I: SPACE REQUIRED- measure the mesio-distal
dimension of all four lower incisors and sum it up.
Using the...
Moyer’s Probability Tables
TANAKA AND JOHNSTON
ANALYSIS (1974)
• They developed a method to predict the width of un-erupted canine
and premolar using...
CONCLUSION
Mixed dentition analysis forms an integral
aspect of orthodontic diagnosis to determine
whether the treatment p...
RECENT ADVANCES IN
MODEL ANALYSIS
Cast analysis by E Models/ 3D Digital Models
ADVANTAGES OF
COMPUTERIZED ANALYSIS
• More Accurate
• Easy
• More information:
– Arch form
– Determine asymmetric Arch
– S...
REFRENCES:
William R. Proffit 5th
edition.
OP Kharbanda 2nd
edition.
S.M Bhalajhi 5th
edition.
Orthodontic Study Model Analysis
Nächste SlideShare
Wird geladen in …5
×

Orthodontic Study Model Analysis

22.427 Aufrufe

Veröffentlicht am

A brief overview on Orthodontic Study Model Analysis

Veröffentlicht in: Gesundheit & Medizin
  • Als Erste(r) kommentieren

Orthodontic Study Model Analysis

  1. 1. MODEL ANALYSIS MODEL ANALYSIS Submitted By :- Dibya Falgoon Sarkar North Bengal Dental College & Hospital
  2. 2. INTRODUCTION • Model analysis is one of the essential diagnostic aids in orthodontics. • The study model provides a three dimensional view of the maxillary and mandibular dental arches in all three planes of space, i.e., sagittal, vertical and transverse planes. • Model analysis allows us to carefully examine several parameters such as dentition, jaw relationships and make objective measurements for detailed evaluation and treatment planning. • Helps in detecting midline discrepancies
  3. 3. REQUSITES OF STUDY MODELS • Should accurately reproduce all the teeth and soft tissues without any distortion. • Should be trimmed symmetrical on either side. • Posterior surface should be trimmed, such that when placed on their back they should reproduce the occlusal plane. • Should reproduce the alveolar process as much as possible.
  4. 4. PARTS OF A STUDY MODEL • Anatomic PortionAnatomic Portion - Consists of the actual impressions of the dental arch & its surrounding structures. • Artistic PortionArtistic Portion - Consists of the plaster base that supports the anatomic portion and helps in analysing the occlusion & orientation of the study models. • The ratio of the anatomic portion to the artistic portion should be 3:1.
  5. 5. According to ABO (1990) Guidelines Lateral view of the study model 1.Base of the maxillary cast is trimmed parallel to the occlusal plane. 2. Upper & lower cast base should be parallel.
  6. 6. Maxillary occlusal view of study model
  7. 7. Mandibular occlusal view of study model
  8. 8. REQUIREMENTS TO DO MODEL ANALYSIS • Well prepared study models • Vernier calipers • Divider • Ruler • 0.033” Soft Brass wire
  9. 9. CLASSIFICATION PERMANENT DENTITION MODEL ANALYSIS MIXED DENTITION MODEL ANALYSIS Arch perimeter analysis Moyer’s Mixed dentition analysis Carey’s analysis Tanaka and johnston analysis Ashley Howe’s analysis Nance mixed dentition analysis Pont’s analysis Huckaba’s mixed dentition analysis (Radiographic method) Linder Harth analysis Korkhaus analysis Bolton’s analysis
  10. 10. PONT’S ANALYSIS • Pont in 1909, proposed a method of determining the ideal dental arch width in premolar and first molar area based on the sum total of mesio-distal widths of maxillary incisors Pont suggested that : • The ratio of the combined upper incisor width to transverse arch width was ideally 0.80 in the premolar area and 0.64 in the molar area. • He also suggested that the maxillary dental arch should be expanded 1-2 millimeters more during treatment than that found in normal occlusion to allow for relapse.
  11. 11. PONT’S ANALYSIS HELPS IN • Determining whether the dental arch is narrow or is normal in the premolar and molar region for a given sum of widths of incisors. • Determining the need for lateral arch expansion. • Determining how much expansion is possible at the premolar and molar regions.
  12. 12. ANALYSIS • DETERMINATION OF SUM OF INCISORS (SI) • DETERMINATION OF MEASURED PREMOLAR VALUE (MPV) • DETERMINATION OF MEASURED MOLAR VALUE (MMV):
  13. 13. • CALCULATED PREMOLAR VALUE (CPV): or the expected arch width in the premolar region is determined by: CPV = SI X 100 80 • CALCULATED MOLAR VALUE (CMV): or expected arch width in the molar region is determined by: CMV = SI X 100 64
  14. 14. INFERENCE •If the measured value is less than the calculated value, then the arch is narrow for the given sum of incisors width and expansion can be done. •If the measured value is greater than the calculated value, the arch is wider and there is no scope for expansion.
  15. 15. DRAWBACKS • Maxillary laterals are the teeth most commonly missing from the oral cavity. • Peg-shaped laterals can be seen. • The analysis was done from the casts of French population • It does not take skeletal mal-relationships into consideration.
  16. 16. LINDER HARTH ANALYSIS • Linder Harth proposed an index very similar to that of Pont’s analysis. • He made variation in the formula to determine the calculated premolar and molar values • The calculated premolar value (CPV): CPV = SI X 100 85 • The calculated molar value (CMV): CMV = SI X 100 64
  17. 17. KORKHAUS ANALYSIS • This analysis is similar to Pont’s analysis. • Only difference is that it make use of Linder Harth’s formula to determine the ideal width in the premolar & molar regions.
  18. 18. • According to Korkhaus for a given width of the upper incisors a specific value of the perpendicular distance between the mid point of the inter premolar line to the point between the two maxillary central incisors should exist. • An increase in this measurement denotes proclination of the upper anterior teeth, while a decrease in this value denotes retroclined upper anteriors.
  19. 19. Korkhaus’ Measurements
  20. 20. ARCH PERIMETER ANALYSIS • Many malocclusions occur due to discrepancy between arch length & tooth material. • It is done in the upper arch. • Two measurements are required for intra- maxillary analysis of space requirement: 1. Calculation of space required 2. Calculation of space available. • Arch perimeter is the geometrical dental arc formed by teeth at their incisal / cuspal edges.
  21. 21. PROCEDURE • DETERMINATION OF SPACE REQUIRED: • measure the mesiodistal dimension of all the teeth mesial to the first molar (54321│12345) • DETERMINATION OF SPACE AVAILABLE: 1. measure the arch perimeter using brass wire. From mesiobuccal line angle of maxillary right first molar , pass the wire along the buccal cusp and incisal edges in the anterior region, ‘pass the wire on the left quadrant like a mirror image till the mesiobuccal line angle of the left maxillary first molar. 2. Mark the wire and measure the wire, which gives the space available.
  22. 22. • In case of proclined incisors, pass the brass wire in the cingulum region, and if the anterior teeth are retroclined, pass the wire labial to them like a smooth curve.
  23. 23. DETERMINATION OF THE DISCREPANCY •The difference between the space required and space available gives the arch discrepancy or excess. •If the tooth material is more than the arch length, the space available for alignment is not sufficient results in crowding. •If the tooth material is less than the space then there can be spacing.
  24. 24. INTERPRETATION OF ARCH PERIMETER ANALYSIS ARCH LENGTH DISCREPANCY INFERENCE 0 to 2.5 mm Proximal stripping can be carried out to reduce the minimal tooth material excess 2.5 to 5 mm Extraction of second premolar is indicated Greater than 5mm Extraction of first premolar is usually required
  25. 25. CAREY’S ANALYSIS • The arch length-tooth material discrepancy is the main cause for most malocclusions. • This discrepancy can be calculated with the help of Carey’s analysis. • The analysis is carried out in the lower arch.
  26. 26. INTERPRETATION OF CAREY’S ANALYSIS ARCH LENGTH DISCREPANCY INFERENCE 0 to 2.5 mm Proximal stripping can be carried out to reduce the minimal tooth material excess 2.5 to 5 mm Extraction of second premolar is indicated Greater than 5mm Extraction of first premolar is usually required
  27. 27. ASHLEY HOWE ANALYSIS • Ashley Howe considered the crowding of teeth to be the result of deficiency in arch width rather than arch length. • He found the relationship between the twelve teeth anterior to the permanent second molars and the width of the dental arch in first premolar region. • This is usually done in the upper arch.
  28. 28. ANALYSIS • DETERMINATION OF TOOTH MATERIAL (TTM): mesodistal width of all the teeth anterior to the permanent second molars are measured with the help of callipers and all the values are summed up. • DETERMINATION OF PREMOLAR DIAMETER (PMD): it refers to the distance or arch width from the tip of the buccal cusp of one fiirst premolar to the tip of the buccal cusp of opposite first premolar. • DETERMINATION OF PREMOLAR BASAL ARCH WIDTH (PMBAW): measurement of width from canine fossa of one side to another gives us the width of the dental arch at the apical base or junction between the basal bone and the alveolar process.
  29. 29. INFERENCE I • The PMBAW and PMD are compared. • If the PMBAW is greater than the PWD, then it is indicated that arch expansion is possible. • If on the other hand, the PMBAW is less than PMD, then arch expansion is not possible.
  30. 30. INFERENCE II • According to Howe, to achieve a normal occlusion with a full complement of teeth, the basal arch width at the premolar region (PMBAW) should be 44% of the sum of the mesiodistal widths of all the teeth mesial to the second molar (TTM)
  31. 31. INFERENCE PMBAW % CONCLUSION 37% or less It indicates a need for extraction 37-44% Borderline case 44% or more Possibly non extraction if other factors are favorable
  32. 32. BOLTON’S ANALYSIS • Wayne Bolton considered the ratio of the tooth material of the maxillary arch to the mandibular arch i.e M-D widths of upper & lower teeth by nature have predetermined proportions to maintain normal occlusal relaionship. • An alteration in this balance will lead to improper intercuspation, overjet or spacing • Bolton said that extraction of one/several tooth should be done acc. to the ratio of tooth material b/w upper & lower arch to get ideal overjet & overbite .
  33. 33. Measurements • Sum of maxillary 12 • Sum of mandibular 12 • Sum of maxillary 6 • Sum of mandibular 6 • Overall ratio • Anterior ratio
  34. 34. • Overall Ratio = Sum of mandibular 12 *100 Sum of maxillary 12 • For establishing ideal overjet & overbite overall ratio should be 91.3% • If the overall ratio is less than 91.3%, it indicates maxillary tooth material excess. • The amount of maxillary tooth material excess is determined by using the formula • The amount of mandibular tooth excess is determined by: Determining Overall Ratio
  35. 35. • The sum of M-D widths of the mandibular anteriors to the M-D width of the max. anteriors should be 77.2% • The anterior ratio is determined using the following formula: • If < 77.2 , maxillary anterior excess • If >77.2 , mandibular anterior excess Determination of Anterior Ratio :
  36. 36. Disadvanatages of Bolton’s Analysis • Does not take into account the sexual dimorphism in the maxillary canine widths. • Study done on specific population.
  37. 37. MIXED DENTITION ANALYSIS
  38. 38. AIM • The purpose of mixed dentition analysis is to evaluate the amount of space available in the arch for succeeding permanent teeth and necessary occlusal adjustments. • Methods of analysis of archlength during mixed dentition i. Those in which the sizes of unerupted cuspids and premolars are estimated from radiographic images ii. Those in which the sizes of cuspids & premolars are derived from the knowledge of already erupted permanent tooth in the mouth.(Probability Tables) iii.Combination of the above two method
  39. 39. HUCKABA’S MIXED DENTITION ANALYSIS (RADIOGRAPHIC METHOD) • This analysis makes use of a radiograph and study cast to determine the width of unerupted teeth. • Advantages: Easy, practical & relatively accurate. • Disadvantage: Chances of distortion of radiographic image. • IOPAR are preferred over Panoramic Images as they are more accurate.
  40. 40. PRINCIPLE • It is based on the principle that if we measure an object, which can be seen both in radiograph as well as on a cast, then we can compensate for the enlargement of the radiographic image • A simple proportional relationship can be established as follows:
  41. 41. • SPACE AVAILABLE: the arch is divided into segments which are approximately straight lines. The dimensions in each of the segments is measured and added up. • SPACE REQUIRED: for the un-erupted teeth is calculated from the radiographs. The discrepancy is calculated segment wise
  42. 42. • It is based on the premise that there is a reasonably good correlation b/w the size of erupted permanent incisors and the unerupted canines & premolars • This is because a person with large teeth in one part of the mouth will have large teeth elsewhere also, as their development is controlled by the same genetic mechanism. • Here the lower permanent incisors are measured and the mesio-distal widths of unerupted permanent upper and lower canines and premolars is derived from the probability chart. • The mandibular incisors are chosen for measuring as they are the first teeth to erupt in the mixed dentition period. MOYER’S MIXED DENTITION ANALYSIS
  43. 43. PROCEDURE • STEP I: SPACE REQUIRED- measure the mesio-distal dimension of all four lower incisors and sum it up. Using the Moyer’s probability chart find the total mesio-distal width of upper and lower canine and premolars from the upper and lower charts at 75% probability for the given lower incisor dimension. • STEP II: SPACE AVAILABLE- measure the distance between the distal surface of permanent lateral incisors and mesial surface of permanent first molar. Determine the amount of space required for the proper alignment of mandibular incisors. The amount of space left behind gives the space available.
  44. 44. Moyer’s Probability Tables
  45. 45. TANAKA AND JOHNSTON ANALYSIS (1974) • They developed a method to predict the width of un-erupted canine and premolar using the width of lower incisors. • This methods has good accuracy despite a small bias towards over- estimating the un-erupted tooth size. • They have simplified Moyer’s 75% prediction table into a formulas • Predicted width of maxillary canine & premolars = Sum Of Mandibular Incisors + 11 2 • Predicted width of mandibular canine & premolars = Sum of Mandibular Incisors + 10.5 2
  46. 46. CONCLUSION 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.
  47. 47. RECENT ADVANCES IN MODEL ANALYSIS
  48. 48. Cast analysis by E Models/ 3D Digital Models
  49. 49. ADVANTAGES OF COMPUTERIZED ANALYSIS • More Accurate • Easy • More information: – Arch form – Determine asymmetric Arch – Space analysis – Rotation – Prediction
  50. 50. REFRENCES: William R. Proffit 5th edition. OP Kharbanda 2nd edition. S.M Bhalajhi 5th edition.

×