study model / orthodontic courses by indian dental academy

STUDY MODELSSTUDY MODELS

www.indiandentalacademy.comwww.indiandentalacademy.com

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

Contents.Contents. Introduction.Introduction. Diagnostic Aids.Diagnostic Aids. Study Models (Defn).Study Models (Defn). History.History. Purpose of Making Study Models.Purpose of Making Study Models. Objectives ofObjectives of Ideal Ideal Orthodontic Study Models. Orthodontic Study Models. Uses of Study Models.Uses of Study Models. Steps in fabrication of Study Models.Steps in fabrication of Study Models. - Impression Making.- Impression Making. - Disinfection of Impression.- Disinfection of Impression. - Taking a Wax Bite.- Taking a Wax Bite. - Casting.- Casting. - ABO requirements for trimming Study Models.- ABO requirements for trimming Study Models. - Trimming Procedure with Finishing.- Trimming Procedure with Finishing. - Care and Storage of Study Models.- Care and Storage of Study Models.


Model AnalysisModel Analysis.. - - PontsPonts Analysis. Analysis. - - Linder HarthLinder Harth Analysis. Analysis. - - Korkhaus Korkhaus Analysis.Analysis. - Mixed Dentition Analysis.- Mixed Dentition Analysis. Moyer's.Moyer's. Tanaka-Johnston.Tanaka-Johnston. Huckaba.Huckaba. Hixon and OldfatherHixon and Oldfather.. - - Sanin-SavaraSanin-Savara Analysis. Analysis. - - CareysCareys Analysis. Analysis. - - BoltonsBoltons Analysis. Analysis. - - Peck and PeckPeck and Peck Analysis. Analysis. - - HowesHowes Analysis. Analysis.


Methods to determine Asymmetry of Arch dimension and Methods to determine Asymmetry of Arch dimension and Tooth Position.Tooth Position.

- Using Divider.- Using Divider. - Using Symmetrograph.- Using Symmetrograph. Diagnostic Set Up.Diagnostic Set Up. Digital Study Models.Digital Study Models. - e-models.- e-models. - Ora-scanner.- Ora-scanner. - OrthoCAD.- OrthoCAD. References.References.


INTRODUCTION.INTRODUCTION.


Diagnostic Aids.Diagnostic Aids. Comprehensive orthodontic diagnosis is Comprehensive orthodontic diagnosis is

established by use of certain clinical established by use of certain clinical implements called implements called DIAGNOSTIC AIDS.DIAGNOSTIC AIDS.

They are of two types:They are of two types: 1) ESSENTIAL DIAGNOSTIC AIDS1) ESSENTIAL DIAGNOSTIC AIDS 2)SUPPLEMENTAL DIAGNOSTIC AIDS.2)SUPPLEMENTAL DIAGNOSTIC AIDS.


ESSENTIAL DIAGNOSTIC ESSENTIAL DIAGNOSTIC AIDSAIDS

SUPPLEMENTAL SUPPLEMENTAL DIAGNOSTIC AIDSDIAGNOSTIC AIDS

1)CASE HISTORY.1)CASE HISTORY. 1)SPECIALIZED RADIOGRAPHS.1)SPECIALIZED RADIOGRAPHS. OPGOPG LATERALLATERAL PA VIEWPA VIEW

2)CLINICAL EXAMINATION.2)CLINICAL EXAMINATION. 2)ELECTROMYOGRAPHY.2)ELECTROMYOGRAPHY.

3)STUDY MODELS.3)STUDY MODELS. 3)HAND-WRIST RADIOGRAPHS.3)HAND-WRIST RADIOGRAPHS.

4)RADIOGRAPHS.4)RADIOGRAPHS. PERIAPICALPERIAPICAL BITE-WINGBITE-WING PANORAMICPANORAMIC

4)ENDOCRINE TESTS.4)ENDOCRINE TESTS.

5)FACIAL PHOTOGRAPHS.5)FACIAL PHOTOGRAPHS. 5)BMR ESTIMATION.5)BMR ESTIMATION.

6)OCCLUSOGRAMS.6)OCCLUSOGRAMS.www.indiandentalacademy.comwww.indiandentalacademy.com

STUDY MODELS.STUDY MODELS.

Orthodontic study models are essential Orthodontic study models are essential diagnostic records, which are accurate plaster diagnostic records, which are accurate plaster reproductions of the teeth and their supporting reproductions of the teeth and their supporting soft tissues and which help to study the soft tissues and which help to study the occlusion and dentition from all the three occlusion and dentition from all the three dimensions.dimensions.


““No matter how astute you are, no matter how No matter how astute you are, no matter how carefully you look into your dental mirror,no carefully you look into your dental mirror,no matter how you bend your head to get a better matter how you bend your head to get a better view of the patients mouth as he sits in the view of the patients mouth as he sits in the dental chair with his jaws spread apart, you dental chair with his jaws spread apart, you cannot achieve the degree of accuracy and cannot achieve the degree of accuracy and attain the completeness that an analysis of attain the completeness that an analysis of study casts will permit. An additional “plus” is study casts will permit. An additional “plus” is that you have a time linked, a that you have a time linked, a longitudinal ,three dimensional record that longitudinal ,three dimensional record that establishes the status of the teeth and establishes the status of the teeth and investing tissues at that particular time.” investing tissues at that particular time.”

- GRABER.- GRABER.www.indiandentalacademy.comwww.indiandentalacademy.com

History.History. PFAFFPFAFF IN 1756 FIRST TIME OBTAINED A IN 1756 FIRST TIME OBTAINED A

NEGATIVE PRODUCED FROM WAX AND NEGATIVE PRODUCED FROM WAX AND FROM IT A POSITIVE MODEL WAS FROM IT A POSITIVE MODEL WAS OBTAINED THROUGH PLASTER OBTAINED THROUGH PLASTER CASTING.CASTING.


Purpose of Making Study Purpose of Making Study Models.Models.

1) Invaluable in planning treatment as they are three-1) Invaluable in planning treatment as they are three-dimensional records of patients dentition.dimensional records of patients dentition.

2)Occlusion can be visualized from all aspects.2)Occlusion can be visualized from all aspects. 3) Provide a permanent record of the intermaxillary 3) Provide a permanent record of the intermaxillary

relationships and the occlusion at the start of relationships and the occlusion at the start of therapy;this is necessary for medico-legal therapy;this is necessary for medico-legal considerations.considerations.

4) Help us to monitor changes taking place during 4) Help us to monitor changes taking place during tooth movements.tooth movements.


Contd.Contd. 5)Helps to motivate the patients as they can visualize 5)Helps to motivate the patients as they can visualize

the treatment progress.the treatment progress. 6)They are needed for comparison purposes at the 6)They are needed for comparison purposes at the

end of treatment and act as a reference for post end of treatment and act as a reference for post treatment changes.treatment changes.

7) Serve as a reminder for the parent and the patient 7) Serve as a reminder for the parent and the patient of the condition present at the start of treatment.of the condition present at the start of treatment.

8)In case the patient has to be transferred to another 8)In case the patient has to be transferred to another clinician ,study models are an important record.clinician ,study models are an important record.


Objectives of Objectives of IdealIdeal Orthodontic Orthodontic Study Models. Study Models.

1)Models accurately reproduce the teeth and their 1)Models accurately reproduce the teeth and their surrounding soft tissues. Soft tissues must not be surrounding soft tissues. Soft tissues must not be altered.altered.

2)Models are to be trimmed so that they are 2)Models are to be trimmed so that they are symmetrical and pleasing to the eye and so that an symmetrical and pleasing to the eye and so that an asymmetrical arch form can be easily recognized.asymmetrical arch form can be easily recognized.

3)Models are to be trimmed in such a way that the 3)Models are to be trimmed in such a way that the dental occlusion shows by setting the models on their dental occlusion shows by setting the models on their backs.backs.

4)Models are to be trimmed so that they meet the 4)Models are to be trimmed so that they meet the measurements and angles as proposed for trimming measurements and angles as proposed for trimming them.them.


Contd.Contd. 5)Models are to have a clean, smooth, bubble 5)Models are to have a clean, smooth, bubble

free surfaces with sharp angles where the cuts free surfaces with sharp angles where the cuts meet.meet.

6)The finished models will be treated with a 6)The finished models will be treated with a soap solution to give it a glassy, mar-proof soap solution to give it a glassy, mar-proof finish. finish.


Uses of Study Models.Uses of Study Models. 1)To assess and record the dental anatomy.1)To assess and record the dental anatomy. 2)To assess and record the intercuspation.2)To assess and record the intercuspation. 3)To assess and record the arch form.3)To assess and record the arch form. 4)To carry out various space analysis.4)To carry out various space analysis. 5)To assess and record the curves of occlusion.5)To assess and record the curves of occlusion. 6)To evaluate occlusion with the aid of articulators.6)To evaluate occlusion with the aid of articulators. 7)To measure progress during treatment.7)To measure progress during treatment. 8)To detect abnormalities. (eg: localized 8)To detect abnormalities. (eg: localized

enlargements,distortion of arch form)enlargements,distortion of arch form) 9)To provide a record before ,immediately after, and 9)To provide a record before ,immediately after, and

several years following treatment for the purpose of several years following treatment for the purpose of studying treatment procedures.studying treatment procedures.


Parts of the Study Models.Parts of the Study Models. ANATOMIC portion.ANATOMIC portion. ARTISTIC portion.ARTISTIC portion.


Anatomic portion.Anatomic portion. Anatomic portion is that part of the study Anatomic portion is that part of the study

model which is the actual impression of the model which is the actual impression of the dental arch and its surrounding structures.dental arch and its surrounding structures.

Usually made of stone plaster.Usually made of stone plaster. Must be preserved while trimming the model.Must be preserved while trimming the model.


Artistic portion.Artistic portion. The artistic portion of study model is a plaster The artistic portion of study model is a plaster

base that supports the anatomic portion.base that supports the anatomic portion. Helps in depicting the actual orientation and Helps in depicting the actual orientation and

the occlusion of study models.the occlusion of study models. Gives a pleasing and symmetrical appearance Gives a pleasing and symmetrical appearance

to the models.to the models.


In a well fabricated set of study models In a well fabricated set of study models the ratio of the anatomic portion to the ratio of the anatomic portion to

artistic portion should be 3:1.artistic portion should be 3:1.


Steps in construction of study Steps in construction of study models.models.

Impression making.Impression making. Taking a wax bite.Taking a wax bite. Disinfection of the impression. Disinfection of the impression. Casting the impression.Casting the impression. Basing and trimming.Basing and trimming. Finishing and polishing.Finishing and polishing. Care of the study models.Care of the study models.


Impression making.Impression making.


Impression making.Impression making. Irreversible hydrocolloids(Irreversible hydrocolloids(alginatealginate) are widely used.) are widely used.

Advantages of alginate:Advantages of alginate: 1)easy to manipulate.1)easy to manipulate. 2)comfortable for the patient.2)comfortable for the patient. 3)relatively inexpensive as it does not require elaborate 3)relatively inexpensive as it does not require elaborate

equipment.equipment. 4)has pleasant taste.4)has pleasant taste. 5)able to displace blood and saliva.5)able to displace blood and saliva. 6)they are hydrophilic.6)they are hydrophilic. 7)they are compatible with stone so it is easy to pour and retrieve 7)they are compatible with stone so it is easy to pour and retrieve

the cast.the cast. 8)they can be used with stock trays.8)they can be used with stock trays.


Orthodontic impression trays.Orthodontic impression trays.

Orthodontic trays are used as their rim in labial Orthodontic trays are used as their rim in labial region is about ¾ inch (20 mm) and their edges are region is about ¾ inch (20 mm) and their edges are beaded.beaded.

Strips of soft utility wax or mortem can be added to Strips of soft utility wax or mortem can be added to tray periphery.tray periphery.


Disinfecting the impression.Disinfecting the impression. First rinse with water.First rinse with water. Immerse it in a disinfectant solution approved Immerse it in a disinfectant solution approved

by O.S.H.A such as Biocide or Chlorhexidine.by O.S.H.A such as Biocide or Chlorhexidine. Be sure to rinse it again with water to remove Be sure to rinse it again with water to remove

the residual disinfectant solution.the residual disinfectant solution.


Taking a wax bite.Taking a wax bite. It should always be taken as it helps the dentist It should always be taken as it helps the dentist

to relate the upper and lower casts in to relate the upper and lower casts in occlusion.occlusion.

Also helps to hold the casts flushed with each Also helps to hold the casts flushed with each other while trimming.other while trimming.


wax bite.JPG

White and Gardiner:White and Gardiner:


Taking a wax bite.Taking a wax bite. Phillip Adams:Phillip Adams: Wax bite should consist of only a bar of Wax bite should consist of only a bar of

moderately softened wax across the premolar moderately softened wax across the premolar region.region.

Graber:Graber: Two layers of soft base-plate wax roughly Two layers of soft base-plate wax roughly

shaped to arch form and warmed in water may shaped to arch form and warmed in water may be used.be used.


Casting the model.Casting the model.


Casting the model.Casting the model. The models may be cast inThe models may be cast in Plain dental plaster.Plain dental plaster. Stone plaster.Stone plaster. Mixture of plain plaster and stone plaster.Mixture of plain plaster and stone plaster. Or the anatomic portion may be cast in stone Or the anatomic portion may be cast in stone

plaster and and bases in plain plaster.plaster and and bases in plain plaster.


RUBBER MOULD BASE RUBBER MOULD BASE FORMERS.FORMERS.


Cross Section of Plaster Casts in Rubber Cross Section of Plaster Casts in Rubber Mould Base Formers:Mould Base Formers:

Occlusal plane should Occlusal plane should be parallel with top and be parallel with top and bottom cast surfaces.bottom cast surfaces.

The back surfaces of the The back surfaces of the casts should be related casts should be related in exactly the same in exactly the same plane ,perpendicular to plane ,perpendicular to top and bottom cast top and bottom cast surfaces.surfaces.


Broussard cast former.Broussard cast former.(Rocky Mountain Dental Products Co.)(Rocky Mountain Dental Products Co.)


STUDY MODEL STUDY MODEL TRIMMING. TRIMMING. (Lawson)(Lawson)


American Board of Orthodontics American Board of Orthodontics requirements for study models. requirements for study models.

(American Board of Orthodontics(American Board of Orthodontics: Specific : Specific Instructions for Candidates, Instructions for Candidates, St Louis,1998, The St Louis,1998, The

Board)Board)


American Board of Orthodontics American Board of Orthodontics requirements for study modelsrequirements for study models


Study model trimming…Study model trimming… Accurate detailed Accurate detailed

impressions are essential to impressions are essential to the production of high the production of high quality study models. quality study models. Before the mandibular cast Before the mandibular cast is poured the tongue space is poured the tongue space must be filled in with must be filled in with alginatealginate..


Study model trimming…Study model trimming… Casting material is carefully Casting material is carefully

proportioned according to proportioned according to the manufacturers the manufacturers instructions.generally , the instructions.generally , the ratio of 30 ml of water to ratio of 30 ml of water to 100g of stone will be 100g of stone will be sufficient to pour one sufficient to pour one model. This should be model. This should be spatulated for 20 to 30 spatulated for 20 to 30 seconds by a vacuum mixer seconds by a vacuum mixer to produce a smooth, dense, to produce a smooth, dense, bubble free mix.bubble free mix.


Study model trimming…Study model trimming… Vibrate the mix into the Vibrate the mix into the

impression so that it flows impression so that it flows slowly from one posterior slowly from one posterior end around to the anterior end around to the anterior and then the other posterior and then the other posterior end. Avoid incorporating air end. Avoid incorporating air bubbles. Fill its base in a bubbles. Fill its base in a like manner. Carefully like manner. Carefully invert the impression onto invert the impression onto its base and add stone to the its base and add stone to the heel areas so that they heel areas so that they extend smoothly into the extend smoothly into the model base surface. Repeat model base surface. Repeat this procedure for the this procedure for the opposing model.opposing model.


Study model trimming…Study model trimming… Cast are allowed to dry Cast are allowed to dry

thoroughly .thoroughly . Now one electric plaster-Now one electric plaster-

trimming machine with a trimming machine with a medium grit,carborundum medium grit,carborundum wheel,grit no. 60 is used for wheel,grit no. 60 is used for trimming.trimming.

Trimmer has dual wheels.Trimmer has dual wheels.


Study model trimming…Study model trimming… A template(or degree A template(or degree

plate) on the model plate) on the model trimmer platform is trimmer platform is used as a reference for used as a reference for holding the casts at a holding the casts at a proper angle while proper angle while trimming.trimming.


Study model trimming…Study model trimming… In addition to no.600 In addition to no.600

wet and dry sand wet and dry sand paper,small and medium paper,small and medium scrapers,lab knife and scrapers,lab knife and some special equipment some special equipment will be used.will be used.

Angle guide.Angle guide. Squaring tool.Squaring tool.


Study model trimming…Study model trimming… Allow the models to dry Allow the models to dry

for one hour after for one hour after pouring.remove the base pouring.remove the base formers and then the formers and then the impression.impression.

Inspect.Inspect.


Study model trimming…Study model trimming… The casts are soaked in The casts are soaked in

water for atleast 10 water for atleast 10 minutes before they are minutes before they are trimmed. Never attempt trimmed. Never attempt to trim a dry model.to trim a dry model.


Study model trimming…Study model trimming… Trim the maxillary cast first. Trim the maxillary cast first.

Remove excess stone from Remove excess stone from the heel areas so that the the heel areas so that the incisors and terminal molar incisors and terminal molar cusp tips will be able to cusp tips will be able to touch the flat plane of the touch the flat plane of the squaring tool squaring tool simultaneously.simultaneously.


Study model trimming…Study model trimming… Position the occlusal Position the occlusal

plane against the plane against the squaring tool .squaring tool .

Check to be sure proper Check to be sure proper contact is being made.contact is being made.


Study model trimming… Study model trimming… Turn on the water supply before Turn on the water supply before

switching on the model trimmer.switching on the model trimmer. While holding the occlusal plane While holding the occlusal plane

of the cast firmly against the of the cast firmly against the squaring tool, slide the whole unit squaring tool, slide the whole unit toward the rough cut wheel. Trim toward the rough cut wheel. Trim away the excess base material so away the excess base material so that the remaining base portion is that the remaining base portion is about one third the total cast about one third the total cast height.height.


Study model trimming…Study model trimming… Draw a line over the Draw a line over the

median palatine raphe.median palatine raphe.


Study model trimming…Study model trimming… A perpendicular line is A perpendicular line is

drawn, about ½ inch distal drawn, about ½ inch distal to the hamular notches.trim to the hamular notches.trim the back of cast to this line.the back of cast to this line.

The back of the cast forms The back of the cast forms right angles with the median right angles with the median palatine raphe.palatine raphe.


Study model trimming…Study model trimming… The buccal segments are The buccal segments are

trimmed at a 70 degree trimmed at a 70 degree angle to the back of the cast. angle to the back of the cast.

To accomplish this, rotate To accomplish this, rotate the degree plate and slide the degree plate and slide the angle guide into place.the angle guide into place.

Press the cast against the Press the cast against the angle guide and trim to angle guide and trim to about 5mm from the buccal about 5mm from the buccal surfaces of teethsurfaces of teeth

Reset the degree plate to Reset the degree plate to trim the other side.trim the other side.


Study model trimming…Study model trimming… Use even, steady Use even, steady

pressure against the pressure against the wheel,but let the model wheel,but let the model trimmer do the work.trimmer do the work.

Both buccal segments Both buccal segments have been trimmed at a have been trimmed at a 70 degree angle.70 degree angle.


Study model trimming…Study model trimming… Change the degree plate Change the degree plate

to indicate a 30-degree to indicate a 30-degree setting and reposition setting and reposition the angle guide.the angle guide.

Trim the maxillary Trim the maxillary anterior portion.anterior portion.

Carefully preserve the Carefully preserve the mucobuccal fold area.mucobuccal fold area.


Study model trimming…Study model trimming… Both anterior angles are Both anterior angles are

complete.complete. Note that each angle Note that each angle

begins at a point at the begins at a point at the middle of the canine.middle of the canine.

The two angles intersect The two angles intersect at a point that is an at a point that is an extension of the median extension of the median palatine raphe line.palatine raphe line.


Study model trimming…Study model trimming… The maxillary posterior The maxillary posterior

segments are trimmed at segments are trimmed at 130-135 degrees angle.130-135 degrees angle.

They should be about ½ They should be about ½ to 5/8 inches wide.to 5/8 inches wide.


Study model trimming…Study model trimming… Occlude the maxillary and Occlude the maxillary and

mandibular casts, trimming mandibular casts, trimming excess stone from the excess stone from the mandibular heels if needed.mandibular heels if needed.

The wax bite registration The wax bite registration wafer should be in place wafer should be in place when trimming occluded when trimming occluded models because the models because the vibration may abrade the vibration may abrade the tooth surfaces.tooth surfaces.


Study model trimming…Study model trimming…

Use the squaring tool to Use the squaring tool to trim the mandibular trim the mandibular base so that it is parallel base so that it is parallel to the maxillary base.to the maxillary base.

The height of the base The height of the base should be about 1/3 rd should be about 1/3 rd the total height of the the total height of the cast.cast.


Study model trimming…Study model trimming… With the casts occluded, With the casts occluded,

trim the back of the trim the back of the mandibular cast so that it is mandibular cast so that it is parallel and flush with the parallel and flush with the maxillary cast.maxillary cast.

This will allow the casts to This will allow the casts to remain in occlusion when remain in occlusion when placed on their backs on a placed on their backs on a flat surface.flat surface.


Study model trimming…Study model trimming… The backs of the The backs of the

maxillary and maxillary and mandibular casts are mandibular casts are trimmed evenly.trimmed evenly.

The mandibular The mandibular posterior corner posterior corner segments are trimmed to segments are trimmed to 130-135 degree 130-135 degree angles,flushed with their angles,flushed with their maxillary counterparts.maxillary counterparts.


Study model trimming…Study model trimming… The buccal segments are The buccal segments are

trimmed at 65-degree trimmed at 65-degree angles to the deepest angles to the deepest part of the buccal part of the buccal vestibule.vestibule.

Do not trim closer than Do not trim closer than 5mm from the buccal 5mm from the buccal surfaces of the teeth.surfaces of the teeth.


Study model trimming…Study model trimming… Make a semicircular Make a semicircular

mark from the center of mark from the center of one canine to the center one canine to the center of the other. This will of the other. This will indicate the anterior indicate the anterior trim line.trim line.

It should be no closer It should be no closer than 5mm from the than 5mm from the labial tooth surfaces.labial tooth surfaces.


Study model trimming…Study model trimming… Carefully trim the Carefully trim the

anterior segment to the anterior segment to the mark.mark.

It should have a It should have a smooth,symmetrical smooth,symmetrical shape.shape.


Study model trimming…Study model trimming… Gently carve any excess Gently carve any excess

material from sulcus material from sulcus areas.areas.

Use a laboratory knife Use a laboratory knife and scraper to remove and scraper to remove blebs and define detail.blebs and define detail.


Study model trimming…Study model trimming… Use extra-fine no.600 Use extra-fine no.600

sandpaper to smooth sandpaper to smooth sulcus areas by hand.sulcus areas by hand.

The tongue area must The tongue area must also be sanded smooth.also be sanded smooth.


Study model trimming…Study model trimming… Use the fine sanding Use the fine sanding

wheel on the model wheel on the model trimmer to smooth trimmer to smooth scratches left by the scratches left by the rough wheel.rough wheel.

Fill any small voids in Fill any small voids in the models with a thin the models with a thin mix of orthodontic mix of orthodontic stone.stone.

Lightly sand again if Lightly sand again if necessary.necessary.


Study model trimming…Study model trimming… Allow the models to dry Allow the models to dry

for 24 hours before putting for 24 hours before putting them in finishing soap them in finishing soap solution. They should be solution. They should be soaked for about 20 soaked for about 20 minutes but not more than minutes but not more than 30, or the models will 30, or the models will dissolve.dissolve.

Rinse off the excess soap Rinse off the excess soap and buff with a soft cotton and buff with a soft cotton cloth.cloth.


Study model trimming…Study model trimming… After the models have After the models have

dried they must be dried they must be labelled.labelled.

Use an indelible marker Use an indelible marker to print the patients to print the patients name and the date the name and the date the impressions were taken.impressions were taken.


Study model trimming…Study model trimming… The study model set is The study model set is

complete.complete. Note the sharp, Note the sharp,

symmetric angles.symmetric angles. The surfaces are sanded The surfaces are sanded

and polished to a and polished to a smooth,attractive luster.smooth,attractive luster.


Study model trimming…Study model trimming… The base of each model The base of each model

is parallel and flush is parallel and flush with the base of the with the base of the other.other.

The set will remain in The set will remain in occlusion when resting occlusion when resting on the heels, or on the on the heels, or on the right or left posterior right or left posterior corners.corners.


Cast trimming to indicate the Cast trimming to indicate the occlusal plane relationships.occlusal plane relationships.

Gnathostatic technique.Gnathostatic technique. Simon in 1926.Simon in 1926. Reproduces the inclination of the occlusal Reproduces the inclination of the occlusal

plane with reference to FH-plane.plane with reference to FH-plane.


Care of study modelsCare of study models. . (White and (White and Gardiner)Gardiner)

Record casts should be kept in boxes holding Record casts should be kept in boxes holding 5-6 sets of models,each pair held together by a 5-6 sets of models,each pair held together by a light elastic band.light elastic band.

A square of thin plastic foam should be kept A square of thin plastic foam should be kept between the occlusal surfaces of the teeth.between the occlusal surfaces of the teeth.

The wax bite should not be left between the The wax bite should not be left between the teeth, however it should be stored as it will be teeth, however it should be stored as it will be of help in finding the occlusal relationship at a of help in finding the occlusal relationship at a later date.later date.


Orthodontic model boxes.Orthodontic model boxes.((J. of Cl. OrthoJ. of Cl. Ortho.,1991)..,1991).

Orthodontic model boxes can be used for systematic Orthodontic model boxes can be used for systematic storage, identification and coding of study models.storage, identification and coding of study models.

BARGER model boxBARGER model box: lid style. Stores 8 models per box.: lid style. Stores 8 models per box. FUNT model boxFUNT model box: drawer style. Stores 4 models per : drawer style. Stores 4 models per

drawer, 8 models per box.drawer, 8 models per box. ARTICULATED model boxARTICULATED model box: drawer style. For tall : drawer style. For tall

mounted models.mounted models. Space maintainer lab, Indiana.Space maintainer lab, Indiana. North Western paper box company,Washington.North Western paper box company,Washington. The Board foot, Texas: Model display cabinets.The Board foot, Texas: Model display cabinets.


Model Analysis.Model Analysis.


PontsPonts analysis. analysis. In 1909,In 1909, Pont Pont devised a method of devised a method of

predetermining an “ideal”arch width based on predetermining an “ideal”arch width based on the mesiodistal widths of the crowns of the the mesiodistal widths of the crowns of the maxillary incisors.maxillary incisors.

Pont Pont suggested that the ratio of combined suggested that the ratio of combined incisor to transverse arch width was ideally incisor to transverse arch width was ideally 0.8 in the bicuspid area and 0.64 in the first 0.8 in the bicuspid area and 0.64 in the first molar area.molar area.


1)Sum of mesio-distal widths of incisors. 1)Sum of mesio-distal widths of incisors. 2)Measured premolar value.2)Measured premolar value.

3)Measured molar value.3)Measured molar value.


Ponts Ponts analysis, contd..analysis, contd.. Expected arch width at premolar region:Expected arch width at premolar region: sum of incisorssum of incisors * 100 * 100 8080Expected arch width at molar region:Expected arch width at molar region: sum of incisorssum of incisors * 100 * 100 6464


PontsPonts analysis contd.. analysis contd.. PontsPonts also suggested that maxillary arch also suggested that maxillary arch

should be expanded 1-2mm more during should be expanded 1-2mm more during treatment than his value to allow for relapse.treatment than his value to allow for relapse.

Thus, amount of expansion that can be done Thus, amount of expansion that can be done on molar and premolar region is estimated.on molar and premolar region is estimated.


Drawbacks of Drawbacks of PontsPonts analysis: analysis: Researchers at University of Washington Researchers at University of Washington

(Dent Clin North Am 1978)(Dent Clin North Am 1978) found very found very poor correlation between combined maxillary poor correlation between combined maxillary incisor widths and the ultimate arch width in incisor widths and the ultimate arch width in the bicuspid and molar areas.the bicuspid and molar areas.

Does not take skeletal mal-relation into Does not take skeletal mal-relation into consideration.consideration.

Analysis is derived solely from casts of French Analysis is derived solely from casts of French population,so it can’t be applied globally.population,so it can’t be applied globally.


Linder HarthLinder Harth index. index. Similar to Similar to PontsPonts analysis. analysis. Variation in formula to determine the expected arch Variation in formula to determine the expected arch

widths at molar and premolar regions.widths at molar and premolar regions. Expected arch widths at premolar region:Expected arch widths at premolar region: Sum of incisors Sum of incisors * 100. * 100. 8585 Expected arch width at molar region: Expected arch width at molar region: Sum of incisors Sum of incisors * 100. * 100. 6565


KorkhausKorkhaus analysis. analysis. It makes use of It makes use of Linder HarthLinder Harth

formula to determine the ideal arch formula to determine the ideal arch width in the premolar and molar width in the premolar and molar region.region.

A measurement is also made from A measurement is also made from the midpoint of inter-premolar line the midpoint of inter-premolar line to a point in between two maxillary to a point in between two maxillary incisors.incisors.

According toAccording to Korkhaus Korkhaus “For a “For a given width of upper given width of upper incisors, a specific value of incisors, a specific value of the distance between the the distance between the midpoint of inter-premolar midpoint of inter-premolar line to the point between line to the point between the two maxillary incisors the two maxillary incisors should exist.” should exist.”

An increase in this measurement An increase in this measurement indicates proclined upper incisors indicates proclined upper incisors while a decrease in this value while a decrease in this value indicate retroclined upper incisorsindicate retroclined upper incisors ..


Sanin-SavaraSanin-Savara tooth size analysis. tooth size analysis.((Am J OrthodAm J Orthod 1971) 1971)

Scholars at University of Oregon devised a Scholars at University of Oregon devised a simple and indigenous procedure to simple and indigenous procedure to identify identify individual and group tooth size individual and group tooth size disharmoniesdisharmonies..

It makes use of precise mesio-distal It makes use of precise mesio-distal measurements of the crown size of each measurements of the crown size of each tooth,appropriate tables of tooth size tooth,appropriate tables of tooth size distribution in the population, and a chart for distribution in the population, and a chart for plotting the patients measurements.plotting the patients measurements.


HowesHowes analysis. analysis.((Am J OrthodAm J Orthod 1954, 1954, Am J OrthodAm J Orthod 1960) 1960)

Ashley HoweAshley Howe devised the formula to determine devised the formula to determine whether the apical bases could accommodate the whether the apical bases could accommodate the patients teeth.patients teeth.

He considered tooth crowding to be due to deficiency He considered tooth crowding to be due to deficiency in arch width rather than arch length.in arch width rather than arch length.

Determination of total tooth material.(TM)Determination of total tooth material.(TM) Determination of premolar diameter(PMD)Determination of premolar diameter(PMD) Determination of premolar basal arch Determination of premolar basal arch

width(PMBAW)width(PMBAW) Determination of BAL.Determination of BAL.


HOWESHOWES ANALYSIS. ANALYSIS.


HowesHowes analysis, contd.. analysis, contd.. If PMBAW is greater than PMD, arch expansion is possible.If PMBAW is greater than PMD, arch expansion is possible. HowesHowes believed that the PMBAW should equal approximately believed that the PMBAW should equal approximately

44%of the TTM if it is sufficiently large to accommodate all 44%of the TTM if it is sufficiently large to accommodate all the teeth.the teeth.

When the ratio between PMBAW and TTM is less than When the ratio between PMBAW and TTM is less than 37%,37%,HoweHowe considered this to be a basal arch deficiency considered this to be a basal arch deficiency necessitating extraction of premolars.necessitating extraction of premolars.

HowesHowes analysis is useful in planning treatment of problems analysis is useful in planning treatment of problems with suspected apical base deficiencies and deciding whether with suspected apical base deficiencies and deciding whether to;to;

1)extract teeth.1)extract teeth. 2)widen the dental arch, or 2)widen the dental arch, or 3)expand rapidly the palate.3)expand rapidly the palate.


BoltonBolton tooth ratio analysis. tooth ratio analysis. ((Angle OrthodAngle Orthod 1958, 1958, Am J OrthodAm J Orthod 1962) 1962)

BoltonBolton studied the interarch effects of discrepancies studied the interarch effects of discrepancies in tooth size to devise a procedure for determining the in tooth size to devise a procedure for determining the ratio of total mandibular versus maxillary tooth size ratio of total mandibular versus maxillary tooth size and anterior mandibular versus maxillary tooth size.and anterior mandibular versus maxillary tooth size.

Study of these ratios help inStudy of these ratios help in 1)estimating the overjet and overbite relationships that 1)estimating the overjet and overbite relationships that

will likely obtain after the treatment is finished.will likely obtain after the treatment is finished. 2)estimating the effects of contemplated extractions 2)estimating the effects of contemplated extractions

on posterior occlusion and incisor relationships,andon posterior occlusion and incisor relationships,and 3)the identification of occlusal misfit produced by 3)the identification of occlusal misfit produced by

interarch tooth size incompatibilities.interarch tooth size incompatibilities.


Procedure.Procedure. Sum of mandibular 12.Sum of mandibular 12. Sum of maxillary 12.Sum of maxillary 12. Sum of mandibular 6.Sum of mandibular 6. Sum of maxillary 6.Sum of maxillary 6. are measured.are measured.


Determination of Overall ratio:Determination of Overall ratio: According toAccording to Bolton Bolton, a mean ratio of 91.3 will , a mean ratio of 91.3 will

result in ideal overjet-overbite relationships, as result in ideal overjet-overbite relationships, as well as posterior occlusion.well as posterior occlusion.

Overall ratio=Overall ratio=sum of mandibular12*100.sum of mandibular12*100. sum of maxillary12.sum of maxillary12. If it is less than 91.3%,it indicates maxillary If it is less than 91.3%,it indicates maxillary

tooth material excess and it indicates tooth material excess and it indicates mandibular tooth material excess if it is more mandibular tooth material excess if it is more than 91.3%.than 91.3%.


Contd..Contd.. Amount of maxillary excess:Amount of maxillary excess: sum of maxillary12- sum of maxillary12- sum of mand.12*100.sum of mand.12*100. 91.3.91.3. Amount of mandibular excess:Amount of mandibular excess: sum of mandib.12- sum of mandib.12- sum of max.12*100.sum of max.12*100. 91.3.91.3.


Contd..Contd.. A similar ratio is computed for six anterior teeth.A similar ratio is computed for six anterior teeth. An anterior ratio of 77.2 will provide ideal overjet An anterior ratio of 77.2 will provide ideal overjet

and overbite relationships and overbite relationships ifif the angulations of the angulations of incisors are correct and incisors are correct and ifif the labio-lingual thickness the labio-lingual thickness of the incisal edge is not excessive.of the incisal edge is not excessive.

If anterior ratio exceeds 77.2,there is excessive If anterior ratio exceeds 77.2,there is excessive mandibular tooth material and if it is less than mandibular tooth material and if it is less than 77.2,there is excess maxillary tooth material.77.2,there is excess maxillary tooth material.

Bolton Bolton analysis predictions do not take into account analysis predictions do not take into account the sexual dimorphism in maxillary cuspid widths.the sexual dimorphism in maxillary cuspid widths.


Careys Careys analysisanalysis..

Determination of arch length.Determination of arch length. Determination of tooth material.Determination of tooth material. Determination of discrepancy.Determination of discrepancy. Inference;Inference;1)If discrepancy is 0-1)If discrepancy is 0-

2.5mm,proximal stripping.2.5mm,proximal stripping.2)If discrepancy is between 2.5-5 2)If discrepancy is between 2.5-5

mm,extract the second premolars.mm,extract the second premolars.3)If discrepancy is more than 5mm, 3)If discrepancy is more than 5mm,

extract first premolarsextract first premolars. .


Peck and PeckPeck and Peck Index. Index. It is done in lower arch.It is done in lower arch. Peck and PeckPeck and Peck suggested certain clinical suggested certain clinical

guidelines on the basis of observation guidelines on the basis of observation that :Persons with ideal incisal arrangement that :Persons with ideal incisal arrangement had smaller mesio-distal width and had smaller mesio-distal width and comparatively larger labio-lingual width than comparatively larger labio-lingual width than in persons with incisal crowding.in persons with incisal crowding.


Procedure:Procedure: Measure the mesio-distal width(M.D) and the labio-Measure the mesio-distal width(M.D) and the labio-

lingual width(L.D) of each of mandibular incisors.lingual width(L.D) of each of mandibular incisors. Calculate the proportion of the mesiodistal width of Calculate the proportion of the mesiodistal width of

each tooth to the labio-lingual width of the tooth by each tooth to the labio-lingual width of the tooth by using the formula:using the formula:

M.D.M.D. *100. *100. L.L/F.LL.L/F.L Mean value for lower central incisor should be 88-Mean value for lower central incisor should be 88-

92%.92%. Mean value for lower lateral incisor should be 90-Mean value for lower lateral incisor should be 90-

95%.95%.


Inference.Inference.

If the value for a given case is more than the If the value for a given case is more than the mean value then, mesio-distal width of the mean value then, mesio-distal width of the tooth is more than the labio-lingual width and tooth is more than the labio-lingual width and hence proximal stripping is indicated in such hence proximal stripping is indicated in such cases.cases.


Mixed Dentition Analysis.Mixed Dentition Analysis. The purpose of mixed dentition analysis is to evaluate The purpose of mixed dentition analysis is to evaluate

the amount of space available in the arch for the amount of space available in the arch for succeeding permanent teeth and necessary occlusal succeeding permanent teeth and necessary occlusal adjustments.adjustments.

This analysis helps one estimate the amount of This analysis helps one estimate the amount of spacing or crowding which would exist for the patient spacing or crowding which would exist for the patient if all the primary teeth were replaced by their if all the primary teeth were replaced by their successors.successors.


Contd..Contd.. Methods fall in two categories:Methods fall in two categories:1)sizes of un-erupted cuspids and premolars are estimated from 1)sizes of un-erupted cuspids and premolars are estimated from

measurements of the radiographic image.measurements of the radiographic image.2)sizes of un-erupted cuspids and premolars are derived from 2)sizes of un-erupted cuspids and premolars are derived from

knowledge of the sizes of permanent teeth already erupted in the knowledge of the sizes of permanent teeth already erupted in the mouth.mouth.

Moyer'sMoyer's advocated type 2 because: advocated type 2 because:1)it has minimal systematic error and range of such errors is known.1)it has minimal systematic error and range of such errors is known.2)it can be done with equal reliability by beginners and expert, as it 2)it can be done with equal reliability by beginners and expert, as it

does not presume sophisticated clinical judgment.does not presume sophisticated clinical judgment.3)it is not time consuming.3)it is not time consuming.4)it does not require special equipments for radiographic projections.4)it does not require special equipments for radiographic projections. The mandibular incisors have been chosen for measuring.The mandibular incisors have been chosen for measuring.


Procedure in the mandibular Procedure in the mandibular arch:arch:

Measure with a tooth measuring guage or a pointed Measure with a tooth measuring guage or a pointed Boley guage, the greatest m-d width of each of the Boley guage, the greatest m-d width of each of the mandibular incisors.mandibular incisors.


Mixed dentition analysis..Mixed dentition analysis.. Determine the Determine the

space needed for space needed for alignment of alignment of incisors.incisors.

Compute the amount Compute the amount of space available of space available after incisor after incisor alignment.alignment.


Mixed dentition analysis..Mixed dentition analysis.. Now,predict the size of the combined widths Now,predict the size of the combined widths

of cuspid, first bicuspid, and second bicuspids.of cuspid, first bicuspid, and second bicuspids. Long method-(Moyer's)Long method-(Moyer's) Prediction of the combined widths of Prediction of the combined widths of

cuspid,first bicuspid and second bicuspidis cuspid,first bicuspid and second bicuspidis done by use of probability charts.done by use of probability charts.


Mixed dentition analysis..Mixed dentition analysis.. No one figure can indicate the precise cuspid-No one figure can indicate the precise cuspid-

bicuspid sum for all people, since there is a bicuspid sum for all people, since there is a range of posterior tooth widths seen even range of posterior tooth widths seen even when the incisors are identical.when the incisors are identical.

The value at 75% is chosen as the estimate.The value at 75% is chosen as the estimate. Theoretically, one should use the 50% level of Theoretically, one should use the 50% level of

probability, since any errors would then probability, since any errors would then distribute equally.distribute equally.


Mixed dentition analysis..Mixed dentition analysis.. Short method Short method :(:(Tanaka and Johnston, J Am Tanaka and Johnston, J Am

Dent Assoc 1974).Dent Assoc 1974). Add the widths of mandibular incisors and divide Add the widths of mandibular incisors and divide

by 2.by 2. To the value obtained add 10.5 mm to predict To the value obtained add 10.5 mm to predict

the combined widths of the mandibular cuspid the combined widths of the mandibular cuspid and bicuspids and 11.0 mm to predict the and bicuspids and 11.0 mm to predict the combined widths of maxillary cuspid and combined widths of maxillary cuspid and bicuspids.bicuspids.

This is a less precise method which does not This is a less precise method which does not allow for sexual dimorphisms with equal allow for sexual dimorphisms with equal accuracy.accuracy.


Mixed dentition analysis..Mixed dentition analysis.. Now, compute the amount of space left in the Now, compute the amount of space left in the

arch for molar adjustment by subtracting the arch for molar adjustment by subtracting the estimated cuspid and bicuspid size from the estimated cuspid and bicuspid size from the measured space available in the arch after measured space available in the arch after alignment of incisors.alignment of incisors.


Procedure for maxillary arch:Procedure for maxillary arch: Similar to that of lower arch with two Similar to that of lower arch with two

exceptions:exceptions: 1) a different probability chart is used for 1) a different probability chart is used for

predicting the upper cuspid and bicuspid sum.predicting the upper cuspid and bicuspid sum. 2) allowance must be made for overjet 2) allowance must be made for overjet

correction when measuring the space to be correction when measuring the space to be occupied by the aligned incisors.occupied by the aligned incisors.


Problems:Problems: A problem arises when considering the space left for A problem arises when considering the space left for

molar adjustment.molar adjustment. Perhaps the most severe limitation of Mixed Perhaps the most severe limitation of Mixed

Dentition analysis is their inability to reflect the Dentition analysis is their inability to reflect the position of the incisors with respect to the skeletal position of the incisors with respect to the skeletal profile.profile.

A problem is imposed when the occlusal curve is A problem is imposed when the occlusal curve is assumed to be a flat plane. Here it becomes obvious assumed to be a flat plane. Here it becomes obvious that mixed dentition analysis is a two-dimensional that mixed dentition analysis is a two-dimensional visualization of a complex three-dimensional visualization of a complex three-dimensional problem.problem.


Hixon and Oldfather’sHixon and Oldfather’s method. method.((Am J OrthodAm J Orthod 1980) 1980)

The mesio-distal width of the mandibular central and The mesio-distal width of the mandibular central and lateral incisor is obtained from the casts.lateral incisor is obtained from the casts.

Determine the width of the un-erupted premolars Determine the width of the un-erupted premolars from the intra-oral peri-apical radiographs made from the intra-oral peri-apical radiographs made using long cone technique.using long cone technique.

Add the width of central and lateral incisors with the Add the width of central and lateral incisors with the width of un-erupted premolars of that particular side.width of un-erupted premolars of that particular side.

The estimated sum total width of the cuspids and The estimated sum total width of the cuspids and bicuspids of that particular side can be obtained from bicuspids of that particular side can be obtained from the given chart.the given chart.


Hixon and Hixon and OldfatherOldfather

values.values. Every measured sum Every measured sum

width of incisors and width of incisors and bicuspids has a bicuspids has a corresponding sum corresponding sum width of the cuspids and width of the cuspids and bicuspids in the chart.bicuspids in the chart.

Measured values in Measured values in mm.mm.

Estimated tooth Estimated tooth size in mm.size in mm.

2323 18.418.4

2424 19.019.0

2525 19.719.7

2626 20.320.3

2727 21.021.0

2828 21.621.6

2929 22.322.3


A revision of the A revision of the Hixon and OldfatherHixon and Oldfather mixed-dentition prediction methodmixed-dentition prediction method..

By Robert Staley and By Robert Staley and Paul Kerber.Paul Kerber.

Graph shows Graph shows relationship between relationship between size of lower incisors size of lower incisors measured from cast plus measured from cast plus lower first and second lower first and second premolars measured premolars measured from radiographs (from radiographs (xx--axis) and size of canine axis) and size of canine plus premolars. (plus premolars. (yy-axis).-axis).


Huckaba’sHuckaba’s analysis. analysis.((Dent Clin North AmDent Clin North Am 1964) 1964)

Both study models as well as radiographs are Both study models as well as radiographs are used for determining the width of un-erupted used for determining the width of un-erupted tooth.tooth.

With radiograph, it is necessary to compensate With radiograph, it is necessary to compensate for the enlargement of the radiographic image.for the enlargement of the radiographic image.

This can be done by measuring an object that This can be done by measuring an object that can be seen both on radiograph and and on the can be seen both on radiograph and and on the study model, such as a primary molar tooth.study model, such as a primary molar tooth.


Contd..Contd.. After the measurement, a proportional relationship can then be After the measurement, a proportional relationship can then be

established as follows:established as follows: Actual width of primary molar(X1) Actual width of primary molar(X1) = = Apparent width of primary molar(X2)Apparent width of primary molar(X2) Actual width of unerupted premolar(Y1)Actual width of unerupted premolar(Y1) Apparent width of unerupted premolar(Y2)Apparent width of unerupted premolar(Y2)

Or Y1= Or Y1= X1-Y2X1-Y2.. X2X2 This technique can be used for all ethnic groups.This technique can be used for all ethnic groups.


Functional analysis and Functional analysis and Equilibration of Occlusion.Equilibration of Occlusion.

Study of patterns of attrition and facets of wear.Study of patterns of attrition and facets of wear. A functional mandibular displacement can be A functional mandibular displacement can be

discovered by looking at the inclined planes discovered by looking at the inclined planes and cusps of the teeth on the casts.and cusps of the teeth on the casts.

Return to the mouth to check for prematurities,Return to the mouth to check for prematurities, tooth guidance,tooth guidance, cuspal interference cuspal interference and possible trauma.and possible trauma.


Contd…Contd… Study casts enable the dentist to study these Study casts enable the dentist to study these

things much more clearly and to correct them.things much more clearly and to correct them.

One of the most valuable service the dentist One of the most valuable service the dentist can render is equilibration of patients can render is equilibration of patients occlusion . Without a set of study casts this is occlusion . Without a set of study casts this is a hazardous procedure.a hazardous procedure.


Thank Thank You.You.


Methods to determine Methods to determine Asymmetries of arch dimension Asymmetries of arch dimension

and tooth position.and tooth position.


Method of using dividers to measure from Method of using dividers to measure from the median raphe to estimate asymmetries the median raphe to estimate asymmetries

of the dental arches. of the dental arches. (Graber)(Graber)


Use of a symmetrograph to determine Use of a symmetrograph to determine asymmetry in the dental arch. asymmetry in the dental arch. (Graber)(Graber)


Diagnostic set up.Diagnostic set up. Proposed by Proposed by H.D.Kesling.H.D.Kesling. A popular practical technique for visualizing space A popular practical technique for visualizing space

problems in three dimensions in the permanent problems in three dimensions in the permanent dentition is that of cutting of teeth from a set of casts dentition is that of cutting of teeth from a set of casts and resseting them in a more desirable positions is and resseting them in a more desirable positions is called a called a Diagnostic or Prognastic set upDiagnostic or Prognastic set up..

Record casts are not used, since they must be used for Record casts are not used, since they must be used for comparison with the diagnostic set up and with comparison with the diagnostic set up and with progressive record casts.progressive record casts.


Technique.Technique. Obtain an accurate wax bite. Trim the posterior Obtain an accurate wax bite. Trim the posterior

portion of the bases of the casts with the wax bite portion of the bases of the casts with the wax bite interposed so the bases are flush.interposed so the bases are flush.

Drill a hole through the alveolar portion of the casts Drill a hole through the alveolar portion of the casts well below the gingival margin of teeth.well below the gingival margin of teeth.

Insert a fine saw blade through the hole and cut to the Insert a fine saw blade through the hole and cut to the crest of gingival margin between two teeth. Repeat crest of gingival margin between two teeth. Repeat this for all the teeth to be cut off the cast.this for all the teeth to be cut off the cast.

Align the teeth and wax them into the desired Align the teeth and wax them into the desired positions. It is best not to cut all the teeth so that the positions. It is best not to cut all the teeth so that the bite relationship can be kept.bite relationship can be kept.


The Diagnostic Set Up. The Diagnostic Set Up. (before and after)(before and after)


Uses of Diagnostic set up.Uses of Diagnostic set up. Useful in difficult space management problems to Useful in difficult space management problems to

ascertain ,before orthodontic treatment is begun , ascertain ,before orthodontic treatment is begun , precisely the amount and direction each tooth must be precisely the amount and direction each tooth must be moved.moved.

When extractions are contemplated as part of the When extractions are contemplated as part of the orthodontic treatment ,the diagnostic set up will orthodontic treatment ,the diagnostic set up will demonstrate vividly the amount of space created by demonstrate vividly the amount of space created by extractions and the tooth movements necessary to extractions and the tooth movements necessary to close the space.close the space.

Will also aid in choosing which teeth to extract.Will also aid in choosing which teeth to extract. Useful in patient motivation.Useful in patient motivation.


Digital study models.Digital study models.


Obtaining a 3-d study cast image.Obtaining a 3-d study cast image. Standard dental impressions of upper and lower Standard dental impressions of upper and lower

arches using a Thixotropic Vinyl Polysiloxane crown arches using a Thixotropic Vinyl Polysiloxane crown and bridge material.and bridge material.

Impression scanning with an Ora-scanner.Impression scanning with an Ora-scanner. Create an Create an e-e-model Digital Orthodontic Model model Digital Orthodontic Model

using proprietary technology available from using proprietary technology available from Geodigm Corporation.Geodigm Corporation.

The laser sensor accuracy is 0.01mm , which The laser sensor accuracy is 0.01mm , which result in an result in an ee-model 3D surface accuracy of -model 3D surface accuracy of 0.1mm with a Polygonal Mesh size of 30,000 0.1mm with a Polygonal Mesh size of 30,000 polygons per jaw.polygons per jaw.


Ora-scanner.Ora-scanner.


OrthoCAD OrthoCAD software(software(Fairview,NJFairview,NJ).).

Capable of capturing and presenting 3-D study Capable of capturing and presenting 3-D study models.models.

With OrthoCAD digital models clinicians can With OrthoCAD digital models clinicians can easily store, retrieve, diagnose and easily store, retrieve, diagnose and communicate cases electronically, saving all communicate cases electronically, saving all the hassles associated with plaster casts. the hassles associated with plaster casts.


Contd..Contd.. Take alginate impressions of maxillary and Take alginate impressions of maxillary and

mandibular dentition and a bite registration.mandibular dentition and a bite registration. Send these to an OrthoCAD processing facility Send these to an OrthoCAD processing facility

and within few hours,3-D study models are and within few hours,3-D study models are downloaded to orthodontic office.downloaded to orthodontic office.

The process requires an Internet connection, a The process requires an Internet connection, a download utility, and analyzing software.download utility, and analyzing software.


OrthoCAD allows for various OrthoCAD allows for various views of study casts for diagnostic views of study casts for diagnostic purposes.purposes.


Diagnostic tools included with Diagnostic tools included with OrthoCAD.OrthoCAD.

Measurement analysis: Measurement analysis: recorded and saved.recorded and saved.

Midline analysis: study Midline analysis: study models can be virtually models can be virtually split.split.

Overjet and overbite Overjet and overbite analysis.analysis.


Diagnostic tools contd..Diagnostic tools contd.. Occlusogram.Occlusogram. Magnification.Magnification.


Diagnostic tools contd..Diagnostic tools contd.. Antero-posterior and Antero-posterior and

transverse adjustments.transverse adjustments. Notes.Notes.


OrthoCAD. OrthoCAD. In addition to diagnostic tools, software provides the In addition to diagnostic tools, software provides the

orthodontist the ability to print various views, and to orthodontist the ability to print various views, and to ee-mail files to other practitioners directly from the -mail files to other practitioners directly from the program.program.

Efficient magnetic and optical storage.Efficient magnetic and optical storage. 200 3-D study models can be stored on a CD-200 3-D study models can be stored on a CD-

ROM with 650 MB storage space.ROM with 650 MB storage space. A 30 gigabyte hard drive can store 10,000 3-D A 30 gigabyte hard drive can store 10,000 3-D

study models.study models. Cost effective.Cost effective.


At last an adviceAt last an advice:: GRABER- ‘ Take study casts of every patient; learn to GRABER- ‘ Take study casts of every patient; learn to

look for the variations of the normal and the look for the variations of the normal and the departures from the normal. Make a check list so that departures from the normal. Make a check list so that you don’t miss anything. On each subsequent visit, you don’t miss anything. On each subsequent visit, take out the study casts and compare the present take out the study casts and compare the present status of the mouth with that of the study casts taken status of the mouth with that of the study casts taken earlier.earlier.

What changes have occurred?What changes have occurred? Are they favourable or unfavourable?Are they favourable or unfavourable? Is there any drifting, over-eruption, prematurities, Is there any drifting, over-eruption, prematurities,

abnormal facets of wear, overbite problems? abnormal facets of wear, overbite problems? Catch these before they develop.Catch these before they develop. This is dentistry at its best- a preventive and This is dentistry at its best- a preventive and

interceptive service.’interceptive service.’


ReferencesReferences.. Graber TM, Swain BFGraber TM, Swain BF: Orthodontics; Current : Orthodontics; Current

Principles and Techniques, Mosby, 1985.Principles and Techniques, Mosby, 1985. Proffit WRProffit WR: Contemporary Orthodontics, Mosby, : Contemporary Orthodontics, Mosby,

1986.1986. Graber, VandersdallGraber, Vandersdall: Orthodontics; Current : Orthodontics; Current

Principles and Techniques, Mosby, 1994.Principles and Techniques, Mosby, 1994. White TC, Gardiner JH, Leighton BCWhite TC, Gardiner JH, Leighton BC : Orthodontics : Orthodontics

for Dental Students, 1985.for Dental Students, 1985. Moyers Moyers : Handbook of Orthodontics.: Handbook of Orthodontics. LawsonsLawsons: Bench Top Orthodontics.: Bench Top Orthodontics. Phillip Adams, John KerrPhillip Adams, John Kerr : The Design, Construction : The Design, Construction

and Use of Removable Orthodontic Appliancesand Use of Removable Orthodontic Appliances..www.indiandentalacademy.comwww.indiandentalacademy.com

Bolton WABolton WA: Disharmony in tooth size and its relation : Disharmony in tooth size and its relation to the analysis and treatment of malocclusion. to the analysis and treatment of malocclusion. Angle Angle OrthodOrthod 1958;28:113. 1958;28:113.

Howes AEHowes AE: A polygon portrayal of coronal and basal : A polygon portrayal of coronal and basal arch dimensions in the horizontal plane. arch dimensions in the horizontal plane. Am J OrthodAm J Orthod 1954;40:811.1954;40:811.

Sanin C, Savara BSSanin C, Savara BS : Analysis of permanent : Analysis of permanent mesiodistal crown size. mesiodistal crown size. Am J OrthodAm J Orthod 1971; 59:488. 1971; 59:488.

OrthoCAD : OrthoCAD : Seminars in OrthodonticsSeminars in Orthodontics, 1997., 1997. Orthodontic Model Boxes, Orthodontic Model Boxes, J Cl OrthodJ Cl Orthod, 1991., 1991.


Thank youThank you

For more details please visit For more details please visit www.indiandentalacademy.comwww.indiandentalacademy.com


study model / orthodontic courses by indian dental academy

Documents