Model Analysis Important Notes
 Carey’s analysis
 Bolton’s analysis
 According to Bolton, tooth size is an important factor to be taken into consideration for diagnosis and there exists a ratio between mesiodistal widths of maxillary and mandibular teeth
 Bolton’s overall ration is 91.3%
 If overall ratio is less than 91.3%, it indicates maxillary tooth material excess
 Bolton’s anterior tooth ratio is 77.2%
 If anterior ratio is less than 77.2%, it indicates maxillary anterior excess
 Tanaka Johnson analysis
 This analysis does not require any radiographs or reference tables
 The width of unerupted canines and premolars can be predicted based on width of mandibular incisors
 Width of maxillary canine and premolars = 11 + 1/2 width of madibular incisors
 Width of mandibular canine and premolars = 10.2 + 1/2 width of mandibular incisors
 Various model analysis
 Requirements of various analysis
Model Analysis Long Essays
Question 1. Classify diagnostic aids. Write briefly about Model analysis.
Answer.
Diagnostic Aids:
 Essential Diagnostic aids
 Case history
 Clinical examination
 Study models
 Certain radiographs
 Facial photographs
 Supplemental diagnostic aids:
 Specialized radiographs
 Electromyographs
 Hand wrist radiographs
 Endocrines tests
 Estimation of basal metabolic rates
 Diagnostic setup
 Occlusograms
Model Analysis:
Involves study of maxillary and mandibular dental arches in all the three planes of space
 Useful in treatment planning
 Useful in maintaining records
Different Analysis:
Carey’s analysis:
 Determination of arch length – From anterior of first permanent molar to mesial surface of opposite first permanent molar
 Determination of tooth material – Mesiodistal width of teeth from 2nd premolar to 2nd premolar
 Determination of the discrepancy – Difference between arch length and tooth material
 Interference:
 02.5 mm – Proximal stripping
 2.55 mm – Extraction of 1st premolars
 > 5mm – Extraction of 1st premolars
 Interference:
Ashley Howe’s analysis:
 Determination of total tooth material [TTM] – Mesiodistal width of teeth from 1st molar to 1st molars
 Determination of premolar diameter [PMD] – arch width from tip of buccal cusp of 1st premolar to that of opposite side
 Determination of premolar basal arch width [PMBAW] – width from canine fossa of one side to other
 Interference:
 PMBAW% – \(\frac{\text { PMBAW } \times 100}{\text { TTM }}\)
 37 or less – Need for extraction
 44 or more – Nonextraction
 37 to 44 – Borderline cases
 Interference:
Ponts analysis:
 By 1909
 Determination of sum of incisors [SI] – Total mesiodistal width of 4 maxillary incisors
 Determination of measured premolar value [MPV] – From distal pit of upper first premolar to that of opposite side
 Determination of measured molar value [MMV] – From mesial pit of one upper first molar to that of opposite side
Read And Learn More: Orthodontics Short And Long Essay Question And Answers

 Determination of calculated premolar value \((\mathrm{CPV})\mathrm{CPV}=\frac{\mathrm{SI} \times 100}{80}\)
 Determination of calculated molar value [CMV] – CMV = \(\frac{\text { SI } \times 100}{80}\)
 Interference:
 Measured value < Calculated value
 Need for expansion
 Interference:
Bolton’s analysis:
 Sum of maxillary 12 – Total mesiodistal width of one 1st molar to that of other
 Sum of mandibular 6 – Total mesiodistal width of 6 anteriors
 Sum of maxillary 6 – Total mesiodistal width of 6 anteriors
 Determines of overall ratio – Overall ratio = \(\frac{\text { Sum of mandibular } 12}{\text { Sum of maxillary } 12} \times 100\)
 According to Bolton, it should be 91.3%
 If less than 91.3% – Maxillary tooth material excess
 Determination of Anterior Ratio:
 Anterior ratio = \(\frac{\text { Sum of mandibular } 6}{\text { Sum of maxillary } 6} \times 100\)
 According to Bolton, it should be 77.2%
 If less than 77.2% – Maxillary anterior excess
 If more than 77.2% – Mandibular anterior excess
Model Analysis Short Essays
Question 1. Arch perimeter analysis.
Answer.
 Carey’s analysis used for maxillary arch is called arch perimeter analysis
Methods Of Arch Perimeter Analysis:
 Determination of arch length – From anterior of first permanent molar to mesial surface of opposite first permanent molar
 Determination of tooth material – Mesiodistal width of teeth from 2nd premolar to 2nd premolar
 Determination of the discrepancy – Difference between arch length and tooth material
 Interference:
 02.5mm – Proximal stripping
 2.55mm – Extraction of 2nd premolars
 > 5mm – Extraction of 1st premolars
 Interference:
Question 2. Mixed Dentition Analysis.
Answer.
Moyer’s Mixed Dentition Analysis: To evaluate amount of space available in arch for erupting permanent canine and premolar
Procedure Of Mixed Dentition Analysis:
Inference Of Mixed Dentition Analysis:
 Compare tooth size of 3,4 and 5 and arch length available
 Predicted value > arch length available → Crowding
Radiographic method:
 Determine width of unerupted teeth
 Erupted teeth in a radiograph and on a cast
i.e. Width of unerupted tooth to be determined
\(=\frac{\text { Width of tooth erupted on cast } \times \text { Width of tooth erupted on radiograph }}{\text { Width of erupted tooth in oral cavity on radiograph }}\)Question 3. Bolton’s analysis:
Answer.
Methods Bolton’s Analysis:
 Sum of mandibular 12 – Total mesiodistal width of one 1st molar to that of other
 Sum of maxillary 12 – Total mesiodistal width of one 1st molar to that of other
 Sum of mandibular 6 – Total mesiodistal width of 6 anteriors
 Sum of maxillary 6 – Total mesiodistal width of 6 anteriors
 Determination of overall ratio – Overall ratio = \(\frac{\text { Sum of mandibular } 12}{\text { Sum of maxillary } 12} \times 100\)
 According to Bolton, it should be 77.2%
 If less than 91.3% – Maxillary tooth material excess
 Determination of Anterior Ratio:
 Anterior ratio = \(\frac{\text { Sum of mandibular } 6}{\text { Sum of max illary } 6} \times 100\)
 According to Bolton, it should be 77.2%
 If less than 77.2% – Maxillary anterior excess
 If more than 77.2% – Mandibular anterior excess
Model Analysis Short Questions And Answers
Question 1. Assessment of tooth mass discrepancy.
Answer.
 Measure the arch length
 Measure the mesiodistal width of teeth
Discrepancy Of Tooth Mass Discrepancy:
 Difference between arch length measures and tooth material
Inference Tooth Mass Discrepancy:
 02.5mm – Proximal stripping
 2.55mm – Extraction of 2nd premolars
 > 5 mm – Extraction of 1st premolars
Question 2. Ashley Howe’s analysis.
Answer.
Methods Of Ashley Howe’s Analysis:
 Determination of total tooth material [TTM] – Mesiodistal width of teeth from 1st molar to 1st molars
 Determination of premolar diameter [PMD] – arch width from tip of buccal cusp of 1st premolar that of opposite side
 Determination of premolar basal arch width [PMBAW] – width from canine fossa of one side to other
Interference Of Ashley Howe’s Analysis:
 PMBAW%
 37 or less – Need for extraction
 44 or more – Nonextraction
 37 to 44 – Borderline cases
Question 3. Carey’s analysis.
Answer.
Methods Of Carey’s analysis:
 Determination of arch length – From anterior of first permanent molar to mesial surface of opposite first permanent molar
 Determination of tooth material – Mesiodistal width of teeth from 2nd premolar to 2nd premolar
 Determination of the discrepancy – Difference between arch length and tooth material
 Interference:
 02.5mm – Proximal stripping
 2.55mm – Extraction of 2nd premolars
 > 5mm – Extraction of 1st premolars
 Interference:
Question 4. Peck and peck ratio.
Answer.
 It is based on the concept of stability of rotational corrections of lower incisors rather than tooth size considerations
 It is calculated as
 Peck and peck ratio = Mesiodistal width / Faciolingual diameter x 100
 Normal ratio for central incisors is 8892% and for lateral incisors is 9095%
 This ratio is used to determine whether lower incisor teeth are excessively wider mesiodistally or not
Question 5. TanakaJohnston analysis.
Answer.
 TanakaJohnston analysis is mixed dentition analysis
 It predicts the widths of unerupted canines and premolars based on sum of the width of lower incisors
Methods Of TanakaJohnston Analysis:
 Measure the total arch length
 Measure the mesiodistal width of lower four incisors and sum them up
 Divide the value obtained by 2 and
 Add 10.5 mm to obtain the sum of widths of mandibular canines and premolars in one quadrant
 Add 10.5 mm to obatin the sum of widths of maxillary canines and premolars in one quadrant
 Formula to calculate the space available is
 Space available = Total arch length – Sum of the lower incisors + 2 x Calculated width of canine and premolar
Advantages Of TanakaJohnston Analysis:
 Simple and practical
 Accurate
 Require neither radiographs nor reference tables
Question 6. Korkhaus analysis.
Answer.
 Korkhaus in 1938 proposed a study model analysis which reveals anteroposterior malpositioning of incisors in maxillary and mandibular arches
 A measurement is made from the midpoint of the interpremolar line to a point between the two maxillary incisors
 According to Korkhaus, for a given width of upper incisors a specific value of the distance between the two maxillary incisors should exist
 An increase in this measuremnet denotes proclined upper anterior teeth while a decrease in this value denotes retroclined upper anterior teeth
Model Analysis Viva Voce
 Bolton’s analysis proposes that tooth size abnormalities causes malocclusion
 Pont’s analysis indicates the need for expansion rather than extraction
 Peck and Peck is a model analysis of mandibular arch
 Ashley and Howe’s analysis indicate tooth extraction if the premolar basal arch width is less than 37%