Tmj instrumentation /certified fixed orthodontic courses by Indian dental academy

TMJ TMJ INSTRUMENTATIINSTRUMENTATIONON

INDIAN DENTAL ACADEMYLeader in continuing Dental Education

www.indiandetalacademy.comwww.indiandetalacademy.com

1. INTRODUCTION 1. INTRODUCTION 2.NEED FOR RECORDING CR-CO DISCREPANCY2.NEED FOR RECORDING CR-CO DISCREPANCY

1. CR DEFINITION1. CR DEFINITION 2. CO DEFINITION2. CO DEFINITION 3. CRITERIA FOR OPTIMAL FUNCTIONAL OCCLUSION3. CRITERIA FOR OPTIMAL FUNCTIONAL OCCLUSION 4. SIGNS & SYMPTOMS OF CR-CO DISCREPANCY4. SIGNS & SYMPTOMS OF CR-CO DISCREPANCY 5. MOUNTED VS HANDHELD CASTS5. MOUNTED VS HANDHELD CASTS

3.METHODS OF RECORDING MM RELATIONS3.METHODS OF RECORDING MM RELATIONS 4.RECORDING CONDYLAR POSITION4.RECORDING CONDYLAR POSITION

a. FACEBOWa. FACEBOW b. ARTICULATORSb. ARTICULATORS c. MPIc. MPI d. ELECTRONIC MPI d. ELECTRONIC MPI d. AXIOGRAPHYd. AXIOGRAPHY e. COMPUTERISED AXIOGRAPHYe. COMPUTERISED AXIOGRAPHY


INTRODUCTIONINTRODUCTION SYNOVIAL JOINTSYNOVIAL JOINT MOVEMENTSMOVEMENTS can be can be

1. In upper joint space - hinge1. In upper joint space - hinge2. In lower joint space – hinge + gliding2. In lower joint space – hinge + gliding

Goals of orthodontic treatment - harmony Goals of orthodontic treatment - harmony between occlusal function and TMJ.between occlusal function and TMJ.

Occlusion and its role on TMJ health – Occlusion and its role on TMJ health – DEBATABLEDEBATABLE

Ideal occlusal relationship should coincide Ideal occlusal relationship should coincide with ideal condyle-fossa relationship.with ideal condyle-fossa relationship.


RETRUDED AXIS POSITIONRETRUDED AXIS POSITION – – condyles articulate with the thinnest avascular condyles articulate with the thinnest avascular

portion of their respective disksportion of their respective disks anterior-superior position anterior-superior position discernible when the mandible is directed discernible when the mandible is directed

superiorly and anteriorly and restricted to a purely superiorly and anteriorly and restricted to a purely rotary movement about a transverse horizontal rotary movement about a transverse horizontal axis.axis.

CENTRIC OCCLUSIONCENTRIC OCCLUSION The occlusion of opposing teeth when the The occlusion of opposing teeth when the

mandible is in centric relation. mandible is in centric relation. This may or may not coincide with the maximum This may or may not coincide with the maximum

intercuspation position.intercuspation position. www.indiandetalacademy.comwww.indiandetalacademy.com

• RETRUDED CONTACT POSITIONRETRUDED CONTACT POSITION - - occlusal occlusal position when the first tooth contact occurs on the position when the first tooth contact occurs on the path of closure in the retruded axis position. path of closure in the retruded axis position.

• BENNETT ANGLEBENNETT ANGLE – – angle at which the orbiting angle at which the orbiting condyle moves inward during laterotrusive condyle moves inward during laterotrusive movement and is measured in relation to the movement and is measured in relation to the horizontal plane. horizontal plane.

• OCCLUSAL INTERFERENCEOCCLUSAL INTERFERENCE – – It is any tooth It is any tooth contact that inhibits the remaining occluding contact that inhibits the remaining occluding surfaces from achieving stable and harmonious surfaces from achieving stable and harmonious contacts.contacts.


OPTIMAL FUNCTIONAL OCCLUSIONOPTIMAL FUNCTIONAL OCCLUSION

1.1. Musculoskeletally stable position.Musculoskeletally stable position.2.2. Ideal condyle-fossa- disc relationship.Ideal condyle-fossa- disc relationship.3.3. Bilateral occlusal contacts in RCP.Bilateral occlusal contacts in RCP.4.4. RCP =ICP or a slide of < than 1 mm RCP =ICP or a slide of < than 1 mm 5.5. Working side contact during laterotrusion. Working side contact during laterotrusion. 6.6. No contact on balancing side during laterotrusion.No contact on balancing side during laterotrusion.7.7. Full extent of jaw movement has to be recorded.Full extent of jaw movement has to be recorded.8.8. check the end-of-therapy occlusion using mounted check the end-of-therapy occlusion using mounted

models.models.


NORMAL CONDYLE-DISC- FOSSA NORMAL CONDYLE-DISC- FOSSA RELATIONSHIPRELATIONSHIP

ROTHROTH- - acceptable difference between CR and acceptable difference between CR and CO -1.00 mm AP, 1.00 mm in vertical plane CO -1.00 mm AP, 1.00 mm in vertical plane and 0.5 mm in transverse planeand 0.5 mm in transverse plane.. www.indiandetalacademy.comwww.indiandetalacademy.com

SIGNS OF CR-CO DISCREPANCYSIGNS OF CR-CO DISCREPANCY

Occlusal wear.Occlusal wear. Excessive tooth mobility.Excessive tooth mobility. Temporomandibular joint sounds.Temporomandibular joint sounds. Limitation of opening or movement. Limitation of opening or movement. Myofascial pain.Myofascial pain. Contracture of mandibular musculature, making Contracture of mandibular musculature, making

manipulation difficult or impossible.manipulation difficult or impossible. Some types of tongue-thrust swallow.Some types of tongue-thrust swallow.


MOUNTED VS HANDHELD CASTSMOUNTED VS HANDHELD CASTS

CLINICALCLINICAL11.Patients will not willingly bite in CR if that is not .Patients will not willingly bite in CR if that is not

where the teeth fit best.where the teeth fit best.2. An accurate clinical assessment of occlusal 2. An accurate clinical assessment of occlusal

interfacing, even in CR, is suspect if tooth mobility interfacing, even in CR, is suspect if tooth mobility is present. is present.

3. Border movements can be recorded.3. Border movements can be recorded.4. Joint sounds can be heard.4. Joint sounds can be heard.5. Lingual perspective of teeth cannot be seen5. Lingual perspective of teeth cannot be seen..


HAND-HELD CASTSHAND-HELD CASTS1.1. When unmounted casts are set on their trimmed distal When unmounted casts are set on their trimmed distal

borders, only the facial perspective of the static borders, only the facial perspective of the static occlusion can be seen. If the casts are held in the hands occlusion can be seen. If the casts are held in the hands without the wax bite, what is seen cannot be relied on without the wax bite, what is seen cannot be relied on because all three vertical restraints are exclusively because all three vertical restraints are exclusively dental.dental.

2.2. How the teeth interrelate when functioning cannot be How the teeth interrelate when functioning cannot be assessed with hand-held casts.assessed with hand-held casts.

3.3. Lingual perspective can be seen.Lingual perspective can be seen.


MOUNTED MOUNTED MODELS MODELS

HAND HELD HAND HELD CASTSCASTS

VsVs


MOUNTED MODELSMOUNTED MODELS1.1. Tooth mobility avoided by making impressions with Tooth mobility avoided by making impressions with

soft materials to prevent deflection.soft materials to prevent deflection.2.2. once casts are mounted - uncompromised picture of the once casts are mounted - uncompromised picture of the

occlusal conditions can be observed.occlusal conditions can be observed.3.3. Mounted casts lead to better diagnosis, better results, Mounted casts lead to better diagnosis, better results,

and to fewer retention problems.and to fewer retention problems.4.4. How teeth interface in centric relation (CR) and when How teeth interface in centric relation (CR) and when

functioning can be seen facially and lingually without functioning can be seen facially and lingually without patient's avoidance mechanism (proprioception).patient's avoidance mechanism (proprioception).


METHODS OF RECORDING METHODS OF RECORDING MAXILLOMANDIBULAR RELATIONSMAXILLOMANDIBULAR RELATIONS

Thielmann (1939)Thielmann (1939) – spiegelkinometer – spiegelkinometer Sears (1952)Sears (1952) – condyle migrator. – condyle migrator. Posselt (1957)Posselt (1957) – gnathothesiometer – gnathothesiometer BuhnerBuhner – Buhnergraph – for locating centric relation and – Buhnergraph – for locating centric relation and

verification of terminal hinge axis location.verification of terminal hinge axis location. Long (1973)Long (1973) – leaf gauge – shims made of acetate or – leaf gauge – shims made of acetate or

plasticplastic Williamson (1980)Williamson (1980) – vericheck – vericheck SLAVICEK (1988)-SLAVICEK (1988)- SAM articulator and MPI SAM articulator and MPI


VERICHECK by WILLIAMSONVERICHECK by WILLIAMSON

The Vericheck instrument will measure the variation from The Vericheck instrument will measure the variation from centric relation in three planes of spacecentric relation in three planes of space..


RECORDING CONDYLAR POSITIONRECORDING CONDYLAR POSITION

FacebowFacebow ArticulatorsArticulators Mandibular Position Indicator(MPI)Mandibular Position Indicator(MPI) Electronic MPIElectronic MPI AxiographyAxiography Computerised AxiographyComputerised Axiography


FACEBOWFACEBOW First introduced by First introduced by RICHMOND HAYESRICHMOND HAYES- articulating - articulating

calipercaliper Later modified by Later modified by SNOWSNOW Serves to transfer 3-D relationship between Mx. Dental Serves to transfer 3-D relationship between Mx. Dental

arch and starting point of mand. movement.arch and starting point of mand. movement. Transverse hinge axis- passes thru both condyles and Transverse hinge axis- passes thru both condyles and

associated with rotation of mand in vertical direction – associated with rotation of mand in vertical direction – clinical relevanceclinical relevance- orientation of the maxillary cast.- orientation of the maxillary cast.

TypesTypes Arbitrary Arbitrary kinematickinematic


Primary use- mount maxillary cast accurately on Primary use- mount maxillary cast accurately on the articulatorthe articulator

Reference points-Reference points- 1. Posterior- hinge axis1. Posterior- hinge axis 2. Anterior- arbitrary2. Anterior- arbitrary

Most semiadjustable articulators- rely on arbitrary Most semiadjustable articulators- rely on arbitrary hinge axis.hinge axis.

If a discrepancy exists between the hinge axis and If a discrepancy exists between the hinge axis and the articulator axis - premature contact will occur the articulator axis - premature contact will occur on the path of closure on the articulated model, not on the path of closure on the articulated model, not present clinicallypresent clinically


Arbitrary facebow transferArbitrary facebow transfer Anatomic average values used based on the work of Anatomic average values used based on the work of

SNOWSNOW Semiadjustable articulators rely on arbitrary hinge axis Semiadjustable articulators rely on arbitrary hinge axis

location.location. Line from tragus to outer canthus of eyeLine from tragus to outer canthus of eye 11-13 mm from the tragus of ear- arbitrary location.11-13 mm from the tragus of ear- arbitrary location.

Kinematic face bow transferKinematic face bow transfer Required for fully adjustable articulators.Required for fully adjustable articulators. Recorded by using a special bow attached to the mandible Recorded by using a special bow attached to the mandible

and is cemented to the teeth.and is cemented to the teeth.www.indiandetalacademy.comwww.indiandetalacademy.com

Facebow – SAM 2Facebow – SAM 2www.indiandetalacademy.comwww.indiandetalacademy.com

ARTICULATORSARTICULATORS

First described by MITCHELL & WILKIE in 1958First described by MITCHELL & WILKIE in 1958 Articulator- instrument that represents the TMJ and jaws Articulator- instrument that represents the TMJ and jaws

to which the maxillary and mandibular casts are to which the maxillary and mandibular casts are attached. means of reproducing occlusal relationships attached. means of reproducing occlusal relationships outside the mouth. outside the mouth.

must be able to simulate an individual’s jaw movement must be able to simulate an individual’s jaw movement mandibular movements are influenced by many soft mandibular movements are influenced by many soft

tissue factors, hence impossible for jaw movements to be tissue factors, hence impossible for jaw movements to be precisely reproduedprecisely reprodued. .


semiadjustable articulators provide an adequate semiadjustable articulators provide an adequate representation of the true occlusion for orthodontic representation of the true occlusion for orthodontic diagnosis.diagnosis.

Roth and Cordray - it is impossible to believe the Roth and Cordray - it is impossible to believe the clinical finding as a true representation of occlusion clinical finding as a true representation of occlusion - occlusal interferences.- occlusal interferences.

only by articulator mounting can the true occlusion only by articulator mounting can the true occlusion be studied.be studied.


CLASSIFICATION OF CLASSIFICATION OF ARTICULATORSARTICULATORS

FULLY FULLY ADJUSTABLEADJUSTABLE

SEMI-SEMI-ADJUSTABLEADJUSTABLE

NON-ADJUSTABLENON-ADJUSTABLE

fivefive records records all all threethree records records 1 or 21 or 2 records records Face bow recordFace bow record Face bow record Face bow record Face bow recordFace bow record

Centric relation recordCentric relation record Centric relation recordCentric relation record Centric relation recordCentric relation record

Protrusive recordProtrusive record Protrusive recordProtrusive record Protrusive recordProtrusive record

Lateral recordsLateral records Intercondylar distance Intercondylar distance record record


Non adjustable Non adjustable articulatorsarticulators

average values are used to represent the inclination average values are used to represent the inclination of the glenoid fossa and condyle fossa relationship.of the glenoid fossa and condyle fossa relationship.

cannot accurately reproduce an individual’s cannot accurately reproduce an individual’s mandibular excursive movements.mandibular excursive movements.

only accurate position that can be used on a only accurate position that can be used on a nonadjustable articulator is one specific oclusal nonadjustable articulator is one specific oclusal contact position. contact position.


AdvantagesAdvantages::1.1. Inexpensive.Inexpensive.2.2. Less time required to mount the casts.Less time required to mount the casts.3.3. No procedures are required to mount casts.No procedures are required to mount casts.

DisadvantagesDisadvantages::1.1. Restorations cannot be properly planned.Restorations cannot be properly planned.2.2. Additional time is required to adjust the Additional time is required to adjust the

restorations intraorallyrestorations intraorally..


Semi adjustable Semi adjustable articulatorsarticulators

can be modified by adjustments made in the can be modified by adjustments made in the condyle fossa portion of the instrument condyle fossa portion of the instrument

Allows more variability in duplicating Allows more variability in duplicating condylar movements. condylar movements.

It usually has 3 types of adjustmentsIt usually has 3 types of adjustments 1.1. Condylar inclination.Condylar inclination.2.2. Lateral translation movement or Bennett angle.Lateral translation movement or Bennett angle.3.3. Intercondylar distance.Intercondylar distance.


condylar inclinationcondylar inclination: angle at which the condyle : angle at which the condyle descends. can be altered descends. can be altered

Bennett angleBennett angle: angle described by the orbiting : angle described by the orbiting condyle during laterotrusive movements. condyle during laterotrusive movements. semiadjustable articulators allow for a Bennett semiadjustable articulators allow for a Bennett angle movement only in a straight line. angle movement only in a straight line.

Intercondylar distanceIntercondylar distance: : The distance between The distance between the rotational centers of the condyles.Three the rotational centers of the condyles.Three general settings - small, medium and large. general settings - small, medium and large.


Records requiredRecords required 1.1. Facebow transfer.Facebow transfer.2.2. Centric relation interocclusal record.Centric relation interocclusal record.3.3. Eccentric interocclusal recordsEccentric interocclusal records

AdvantagesAdvantages::1.1. The adaptability to patient’s specific condylar movement.The adaptability to patient’s specific condylar movement.2.2. Accurately fitting restorations can be fabricated.Accurately fitting restorations can be fabricated.

Disadvantages:Disadvantages:1.1. Initially more time is required.Initially more time is required.2.2. More expensive than nonadjustable type.More expensive than nonadjustable type.3.3. condylar path is in straight line, unlike the true condylar condylar path is in straight line, unlike the true condylar

path, which follows a curved path.path, which follows a curved path. www.indiandetalacademy.comwww.indiandetalacademy.com

Fully adjustable Fully adjustable articulatorsarticulators

have a large range of adjustability in all three have a large range of adjustability in all three dimensions dimensions

most complex types of articulators most complex types of articulators most sophisticated type for recording most sophisticated type for recording

mandibular movements. mandibular movements. adjustments that can be made areadjustments that can be made are

1.1. Condylar inclination.Condylar inclination.2.2. Bennett angle.Bennett angle.3.3. Rotating condylar movement.Rotating condylar movement.4.4. Intercondylar distanceIntercondylar distance..


Condylar inclinationCondylar inclination::Angle during protrusive and Angle during protrusive and laterotrusive movements can be adjusted. capable of laterotrusive movements can be adjusted. capable of recording curvature of patients condylar movements.recording curvature of patients condylar movements.

Bennett angleBennett angle: : both bennett angle and bennett shift both bennett angle and bennett shift can be recordedcan be recorded..

Rotating condylar movementRotating condylar movement::pathway of the pathway of the rotating condyle duplicates that of the patientrotating condyle duplicates that of the patient..

Intercondylar distanceIntercondylar distance: : can be adjusted in a fully can be adjusted in a fully adjustable articulator to match that in the patient more adjustable articulator to match that in the patient more precisely.precisely.


Records requiredRecords required:: 1.1. An exact hinge axis location.An exact hinge axis location.2.2. A pantographic recording.A pantographic recording.3.3. A centric relation interocclusal record.A centric relation interocclusal record. AdvantagesAdvantages::1.1. Ability to duplicate mandibular movements precisely. Ability to duplicate mandibular movements precisely. 2.2. Stable and anatomic interocclusal relatioship can be Stable and anatomic interocclusal relatioship can be

obtained.obtained.

DisadvantagesDisadvantages::1.1. Considerable amount of time is required.Considerable amount of time is required.2.2. Highly expensive.Highly expensive. www.indiandetalacademy.comwww.indiandetalacademy.com

INDICATIONS FOR ARTICULATOR INDICATIONS FOR ARTICULATOR MOUNTED MODELSMOUNTED MODELS

When a significant discrepancy exists between When a significant discrepancy exists between RCP & ICP (> 2mm). RCP & ICP (> 2mm).

Orthodontic cases with multiple missing teeth. Orthodontic cases with multiple missing teeth. Cases undergoing orthognathic procedures.Cases undergoing orthognathic procedures. Mounting of study models pre orthodontic Mounting of study models pre orthodontic

treatment and pre debond in individuals with treatment and pre debond in individuals with TMD is recommended.TMD is recommended.


USES OF ARTICULATORS IN USES OF ARTICULATORS IN ORTHODONTICSORTHODONTICS

For diagnosis and treatment planning.For diagnosis and treatment planning. For finishing.For finishing. In orthognathic surgical cases.In orthognathic surgical cases.


IN DIAGNOSIS AND TREATMENT PLANNINGIN DIAGNOSIS AND TREATMENT PLANNING Diagnosis carried out with teeth in ICP- misleading - Diagnosis carried out with teeth in ICP- misleading -

inappropriate treatment planinappropriate treatment plan.. small proportion of patients have a large discrepancy small proportion of patients have a large discrepancy

between RCP and ICP.between RCP and ICP. Such large discrepancies are not easy to diagnose Such large discrepancies are not easy to diagnose

clinically.clinically. may be necessary to deprogram the neuromusculature.may be necessary to deprogram the neuromusculature. Articulated models reveal the AP relationship of Articulated models reveal the AP relationship of

maxilla and mandible more accurately. maxilla and mandible more accurately. ease with the visualisation of static and functional ease with the visualisation of static and functional

interrelationships of the teeth.interrelationships of the teeth.www.indiandetalacademy.comwww.indiandetalacademy.com

can be used to aid the clinician whether selective can be used to aid the clinician whether selective grinding can be undertaken.grinding can be undertaken.

sectioning of the teeth and repositioning them in sectioning of the teeth and repositioning them in wax - final results of orthodontics can be visualised.wax - final results of orthodontics can be visualised.

orthodontic setup provides valuable information for orthodontic setup provides valuable information for treatment planning.treatment planning.

Patients with hypodontia and multiple missing teeth Patients with hypodontia and multiple missing teeth may not have a reproducible ICP. only reproducible may not have a reproducible ICP. only reproducible relationship that can be recorded is RCP-requires relationship that can be recorded is RCP-requires articulator mounted models.articulator mounted models. www.indiandetalacademy.comwww.indiandetalacademy.com

ARTICULATORS FOR FINISHINGARTICULATORS FOR FINISHING

Non working side contacts are harmful to the Non working side contacts are harmful to the dentition - trigger bruxism, TMJ disorders or dentition - trigger bruxism, TMJ disorders or instability of tooth position. Hence these instability of tooth position. Hence these interferences have to be eliminated.interferences have to be eliminated.


ARTICULATORS FOR ARTICULATORS FOR ORTHOGNATHIC PLANNINGORTHOGNATHIC PLANNING

essential part of presurgical preparationessential part of presurgical preparation

ramus osteotomies - seperation of tooth bearing parts ramus osteotomies - seperation of tooth bearing parts of mandible from the condyle. no benefit in of mandible from the condyle. no benefit in maintaining condyle tooth relationship during model maintaining condyle tooth relationship during model surgery and hence an arbitrary mounting is sufficient.surgery and hence an arbitrary mounting is sufficient.

maxillary surgery, autorotation of the mandible will maxillary surgery, autorotation of the mandible will

be necessary - the condyle tooth relationship should be necessary - the condyle tooth relationship should be recorded as precisely as possible.be recorded as precisely as possible.


MANDIBULAR POSITION MANDIBULAR POSITION INDICATORINDICATOR

Dynamic and static positions of mandible Dynamic and static positions of mandible determined by:determined by:

1.1. neuromuscular system and proprioceptivity.neuromuscular system and proprioceptivity.2.2. morphology of hard and soft structures of the TMJ.morphology of hard and soft structures of the TMJ.3.3. The morphology of the occlusal surfaces of the teeth.The morphology of the occlusal surfaces of the teeth.4.4. Compromises necessitated by various skeletal patterns.Compromises necessitated by various skeletal patterns.5.5. Head posture and its relationship to the cervical spine.Head posture and its relationship to the cervical spine.6.6. The limits of motion established by ligaments attached The limits of motion established by ligaments attached

to the mandible.to the mandible.


MANDIBULAR POSITION MANDIBULAR POSITION INDICATORINDICATOR

The M.P.I. quantifies differences between RCP & The M.P.I. quantifies differences between RCP & ICP.ICP.

used to perceive whether a clinically determined used to perceive whether a clinically determined symptom or sign can be related to differences symptom or sign can be related to differences between the patient's RCP and ICP, if early signs of between the patient's RCP and ICP, if early signs of discopathy are present, and if a treatment plan to discopathy are present, and if a treatment plan to move the teeth will result in an occlusion in which move the teeth will result in an occlusion in which RCP and ICP are compatible.RCP and ICP are compatible.


MOUNTING OF CASTSMOUNTING OF CASTS

Accurate impressions Accurate impressions

Stone castsStone casts


Base of casts – Base of casts – Split cast former Split cast former


Anatomic facebow oriented to soft tissue porion and orbitaleAnatomic facebow oriented to soft tissue porion and orbitale..


Face bow record transferred to articulatorFace bow record transferred to articulator


Recording centric relationRecording centric relation

Mandible guided into retral Mandible guided into retral position by the position by the operator(guided by the operator(guided by the thumb and forefinger at thumb and forefinger at gnathion)gnathion)


Roth power centricRoth power centric Anterior segment- 3 Anterior segment- 3

thickness wax. Canine- thickness wax. Canine- canine.canine.

Posterior segement – 2 Posterior segement – 2 thickness wax. Molar thickness wax. Molar region.region.


Roth power centric techniqueRoth power centric technique


M.P.I PROCEDUREM.P.I PROCEDURE

Adhesive grid paper- on Adhesive grid paper- on incisal tableincisal table

Upper member lowered to Upper member lowered to first contactfirst contact

Incisal pin loweredIncisal pin lowered Grid mark – red markingGrid mark – red marking Vertical height of pin Vertical height of pin

noted.noted.


maxillary cast is transferred maxillary cast is transferred to the M.P.I.to the M.P.I.

M.P.I and upper part of the M.P.I and upper part of the

SAM 2 articulator are SAM 2 articulator are identical, except condylar identical, except condylar housing are replaced with housing are replaced with sliding blocks in the M.P.I sliding blocks in the M.P.I


Mounted maxillary Mounted maxillary cast is interdigitated cast is interdigitated with mandibular castwith mandibular cast

Adhesive grids with Adhesive grids with X, Z coordinates are X, Z coordinates are placed on the lateral placed on the lateral sliding blocks of the sliding blocks of the M.P.I.M.P.I.


Adhesive grid on black Adhesive grid on black cubes of MPIcubes of MPI

Mark position of Mark position of condylar spheres with condylar spheres with black articulating paper black articulating paper (hinge axis position)(hinge axis position)


Incisal pin vertical reading – Incisal pin vertical reading – Delta HDelta H

Horizontal difference between Horizontal difference between RCP &ICP read at incisal RCP &ICP read at incisal table - table - Delta LDelta L

Dial gauge reading – Dial gauge reading – Delta YDelta Y


Cubes slid medially to Cubes slid medially to perforate grid.perforate grid.

Point of perforation Point of perforation indicates hinge axisindicates hinge axis..


ResultsResults

Delta HDelta H = vertical increase or decrease read from the = vertical increase or decrease read from the incisal pin.incisal pin.

Delta LDelta L = protrusive or retrusive movement measured = protrusive or retrusive movement measured from tne incisal table (grid)from tne incisal table (grid)

Delta XDelta X = protrusive or retrusive. Indicates differences = protrusive or retrusive. Indicates differences in horizontal condylar position.in horizontal condylar position.

Delta ZDelta Z = compression or distraction. Indicates = compression or distraction. Indicates differences in vertical condylar position.differences in vertical condylar position.

Delta YDelta Y = right or left transverse movement. Indicates = right or left transverse movement. Indicates differences in transverse condylar position.differences in transverse condylar position.


ICP (black dot) above ICP (black dot) above RCP (red dot) indicates RCP (red dot) indicates

compression.compression.

ICP (black dot) below ICP (black dot) below RCP (red dot) RCP (red dot) indicates distraction.indicates distraction.


ELECTRONIC MPIELECTRONIC MPI displays data that are the same as those taken displays data that are the same as those taken

manually with the M.P.I. Standard records are manually with the M.P.I. Standard records are designated numerically as the differences between:designated numerically as the differences between:

1. RCP and the intercuspal position (ICP)1. RCP and the intercuspal position (ICP)2. RCP and bilateral joint resilience (RES)2. RCP and bilateral joint resilience (RES)3. RCP and estimated therapeutic position 3. RCP and estimated therapeutic position

(ETP)(ETP)4. RCP and ideal vertical position (IVP)4. RCP and ideal vertical position (IVP)5. RCP and forced bite position (FBP)5. RCP and forced bite position (FBP)

6. ICP and a new ICP after full-mouth6. ICP and a new ICP after full-mouth opening opening www.indiandetalacademy.comwww.indiandetalacademy.com


AXIOGRAPHYAXIOGRAPHY

Axiograph - diagnostic instrument- simulates Axiograph - diagnostic instrument- simulates condylar movement pathways.condylar movement pathways.

The procedure is called The procedure is called AXIOGRAPHYAXIOGRAPHY. The . The graphic output is called graphic output is called AXIOGRAM.AXIOGRAM.

Records movements in all 3 planes of space.Records movements in all 3 planes of space. Early detection of subclinical discopathies.Early detection of subclinical discopathies.


Normal jointNormal joint Reference plane- Reference plane-

hinge axis.hinge axis.

The axiograph The axiograph simultaneously simultaneously records hinge-axis records hinge-axis movements in all 3 movements in all 3 planes.planes.


Facebow of Facebow of axiograph attached axiograph attached to cranium.to cranium.

Hinge-axis bow Hinge-axis bow anchored to the anchored to the mandible with mandible with functional occlusion functional occlusion clutch.clutch.


Tracing of hinge axis movementTracing of hinge axis movement

Three dimensional recording as Three dimensional recording as stylus is replaced by dial gauge.stylus is replaced by dial gauge.


Deranged joint- location and repeatability of a Deranged joint- location and repeatability of a reference position is impossible.reference position is impossible.

Difficulty to locate hinge axis may be due to Difficulty to locate hinge axis may be due to 1.1. Flattened condylar head.Flattened condylar head.2.2. InflammationInflammation3.3. Internal derangement.Internal derangement.4.4. Loose ligaments.Loose ligaments.5.5. Structural asymmetriesStructural asymmetries6.6. Muscle imbalance. Muscle imbalance.


Movements traced areMovements traced are1.1. protrusion-retrusion, protrusion-retrusion, 2.2. opening-closing, opening-closing, 3.3. unguided mediotrusion-medioretrusion, right unguided mediotrusion-medioretrusion, right

and then left; and then left; 4.4. guided mediotrusion-medioretrusion, right and guided mediotrusion-medioretrusion, right and

then leftthen left..

Joint sounds – crepitation and clicking should Joint sounds – crepitation and clicking should be recorded.be recorded.


Bennett movementBennett movement Mediolateral movement of Mediolateral movement of

the mandible measured the mandible measured along the Y axis. along the Y axis.

Bennett value altered byBennett value altered by1.1. Medially displaced Medially displaced

meniscusmeniscus2.2. LuxationLuxation3.3. Subluxation.Subluxation.4.4. Reduction.Reduction.


Resiliency testResiliency test Determines the ability to move the hinge-axis position Determines the ability to move the hinge-axis position

superiorly anteriorly to a loaded positionsuperiorly anteriorly to a loaded position

Children -1mm of resiliency, young adult .5mm, and Children -1mm of resiliency, young adult .5mm, and middle-aged or elderly patients .3mm.middle-aged or elderly patients .3mm.

No joint resiliency- results in deroundation - flattening No joint resiliency- results in deroundation - flattening of the condyle head. Resiliency below normal requires of the condyle head. Resiliency below normal requires treatment with splints.treatment with splints.


Joint resiliency testJoint resiliency test

Upward pressureUpward pressure Condyle displaced Condyle displaced

superiorly & superiorly & anteriorlyanteriorly


Interpretation of Axiograpic Interpretation of Axiograpic TracingsTracings

Sagittal movementsSagittal movements Coincide for first 10-Coincide for first 10-

12mm12mm

Bilaterally symmetricalBilaterally symmetrical

No Bennett movement.No Bennett movement.

(0.2-0.3 mm acceptable)(0.2-0.3 mm acceptable)


Sagittal movementsSagittal movements

When movements do When movements do not coincidenot coincide

1.1. Muscle limitationMuscle limitation2.2. Differentiate between Differentiate between

muscular and muscular and ligamentous limtation.ligamentous limtation.

3.3. Correlate with clinical Correlate with clinical findings.findings.


Protrusion – retrusion tracingsProtrusion – retrusion tracings

Normally coincideNormally coincide in pattern and timing in pattern and timing Position altered by loose ligaments.Position altered by loose ligaments. Asymmetry in timing seen due to in coordination Asymmetry in timing seen due to in coordination

of medial and lateral pterygoids.of medial and lateral pterygoids. Limited movement seen in class II div IILimited movement seen in class II div II No transverse deviation of bennett movement – No transverse deviation of bennett movement –

deviation indicates incipient discopathydeviation indicates incipient discopathy..


Mediotrusion – MedioretrusionMediotrusion – Medioretrusion

principally a unilateral translation, with minimal principally a unilateral translation, with minimal vertical movement.vertical movement.

The condyle head rotates minimally within the The condyle head rotates minimally within the inferior concavity of meniscus.inferior concavity of meniscus.

If tracings do not coincide - indicative of loose If tracings do not coincide - indicative of loose ligaments, subluxation, luxation, or reduction.ligaments, subluxation, luxation, or reduction.

Medially displaced meniscus restricts Medially displaced meniscus restricts movement. movement.


Opening/closing movementsOpening/closing movements Opening movement involves the rotational Opening movement involves the rotational

component of the mandible - is extremely component of the mandible - is extremely important in diagnosing morphological changes important in diagnosing morphological changes in the head of the condyle.in the head of the condyle.

Comparisons between rotational and translatory Comparisons between rotational and translatory movements are paramount to a proper diagnosis. movements are paramount to a proper diagnosis.

Rotational movements- lower joint Rotational movements- lower joint abnormalitiesabnormalities

Translatory movements- upper joint Translatory movements- upper joint abnormalities.abnormalities.


Overrotation of mandibleOverrotation of mandible


Deroundation of condyleDeroundation of condyle


Muscle distractionMuscle distraction


Highly active temporalisHighly active temporalis


Loose jointLoose joint


Functional distractionFunctional distraction


COMPUTER AIDED COMPUTER AIDED AXIOGRAPHYAXIOGRAPHY

enhances the tracking of hinge-axis enhances the tracking of hinge-axis movements in all 3 planes along with timing of movements in all 3 planes along with timing of movement and accuracy.movement and accuracy.

computer displays the condylar movement in computer displays the condylar movement in real time. real time.


Locating hinge axisLocating hinge axis Located by having the patient rotate open, Located by having the patient rotate open,

without translation, for at least 10mm- If the without translation, for at least 10mm- If the stilus is not on the hinge-axis position it will stilus is not on the hinge-axis position it will scribe an arc.scribe an arc.

uses this arc to form a circle and then calculates uses this arc to form a circle and then calculates its center, which is the site of pure rotation— the its center, which is the site of pure rotation— the true hinge-axis.true hinge-axis.

Accuracy of location- 0.01mmAccuracy of location- 0.01mm Accuracy of manual method – 0.2 mmAccuracy of manual method – 0.2 mm
