POSSELT’S ENVELOPE OFMOTIONPRESENTED BY:Urooj Akhtar#39Fasahat Ahmed Butt#36Ausjah Abbas#35
ENVELOPE OF MOTIONDr ulf posselt’s in 1952 first described a 3D conceptof mandibular movementsIt was a Combination of border movements in all 3planes:a) Sagittalb) Horizontalc) FrontalThe envelope differs from person to person but ithas the same characteristic shape
ENVELOPE OF MOTIONThe superior surface of the envelope isdetermined by the tooth contactsThe other borders are primarilydetermined by the TMJ anatomy and theligaments
WHAT ISTEMPOROMANDIBULARJOINT??It is the area where the mandible articulateswith the cranium. It is described as a complex , multiaxial,synovial , condylar and ginglimoarthroidaljoint.Tmj is also known as CRANIOMANDIBULARJOINT.
Cranial componentIt is also known as mandibular/glenoid fossa. Mandibular componentThe articular part of the mandible is an Ovoidcondylar process. Tmj capsuleIt is a thin sleeve fibrous tissue investingjoint completely.Inside fibrous tissue capsule, a synovialmembrane is present.
Ligaments:Following are the ligaments associated withTEMPOROMANDIBULAR JOINT The lateral or temporomandibular ligament Sphenomandibular ligament Stylomandibular ligament
REFERENCE POSITIONSCentric RelationMaximum Intercuspal PositionPostural Position – resting position
CENTRIC RELATIONThe position of the mandible in which the condylesare in the most superior and anterior position in thearticular fossae, resting against the posterior slopesof the articular eminences with the articular discsinterposed.
Maximal Intercuspal Positionor Maximum IntercuspationThis is a position in which the maxillary andmandibular teeth make maximum surface contactwith each other. The mandible is elevated assuperiorly as possible in the sagittal plane.
MAXIMUM INTERCUSPATION(MIP)Tooth determined positionDoes not provide any information about the TMJIn most people, MIP does not coincide with CR
MAXIMUM INTERCUSPATIONIn MIP the condyle-disc assembly is anteriorand inferior and/or medial or lateral or acombination of the above compared to theirposition in CR.Usually the condyle-disc assemblies areANTERIOR and INFERIOR.
POSTURAL POSITION(PP)Is the habitual position of the mandiblewhen the patient is resting comfortably inthe upright position and the condyles arein a neutral unstrained position in theglenoid fossae.In this position there is an equilibriumbetween the forces acting on themandible.
POSTURAL POSITIONIn the POSTURAL POSITION the muscles arenot totally relaxed. There is a degree ofelectromyographic activity.This position is determined by the muscles andthe forces of gravity.
POSTURAL POSITIONThe condyles are usually anteriorly andinferiorly compared to their CR position.This position can be sustained and it iscomfortable for the patient.
POSTURAL POSITIONIn this position, the teeth are apart and thereis a wedge space between the teeth.The wedge shaped space is called theINTEROCCLUSAL SPACE and is usually 2-3mm between the incisors, 2mm between thepremolars, and 0.75-1mm between themolars.
IF OPENING OF THE MANDIBLE CONTINUESBEYOND 20-25 MM THEN TRANSLATION OFTHE MANDIBLE OCCURS.
ROTATIONAL MOVEMENTMovement of a body around an axis• Pure rotational movement occurs minimally inthe mandible• This pure rotational movement is alsoreferred to as hinge movement and the axis isreferred to as terminal hinge axis
PURE ROTATIONAL MOVEMENT ATTERMINAL HINGE AXIS
LATERAL MOVEMENTS(RIGHT AND LEFT DIRECTION)1) The side to which the mandible is moving is called theWORKING SIDE2) The side that is opposite to the working side is calledBALANCING OR NON WORKING SIDE3) The condyle on the working side is called theWORKING OR ROTATING CONDYLE4) The non-working condyle is called THE BALANCINGOR THE ORBITING CONDYLE
MANDIBULAR LATERAL TRANSLATIONThe first part of the lateral movement of the mandible, depicted when themedial pole of non-working condyle starts to travel down the slope of thearticular eminence. The movement is exhibited as a measurement of thedistance between the medial pole of the non-working condyle and the medialwall of the glenoid fossa.Also known as Bennett Movement and Immediate SideshiftNon-Working Side0.3mm
FUNCTIONAL MOVEMENTS(OCCUR WITHIN BORDERMOVEMENTS)Occur during functional activity of themandibleAre confined within the Border MovementsBegin and end in the maximum intercuspationposition.
FUNCTIONALMOVEMENTSThe chewing stroke starts at the MIP anddrops downwards and forwards to theposition of desire opening.It returns in a straighter pathway slightlyposterior.
BORDER MOVEMENTSThe mandibular movements are limited byligaments, the articular surfaces of the TMJ,and the morphology and alignment of theteeth. The outer range of movement isreproducible and called border movements.
PANTOGRAPH APPARATUSThe device has a stylus that marks on specialpaper placed in all 3 planes of reference at thesame time. Distinct markings are produced thatare transferable to a fully adjustable articulator.Recording Paper
PANTOGRAPHIC TRACING TRANSFERTO FULLY ADJUSTABLE ARTICULATORTracing platesreceive markings onpaper duringmovements of themandible. Thearticulator is set by“tracing” themovement recorded
PANTOGRAPHIC TRACINGSHorizontal PlateSagittal PlateHorizontalPlateTracings are captured and depicted in each plane of reference.
Three-dimensional description of theMandibular & Maxillary positioningREFERENCE PLANES
Also known as Axes of RotationReference Planes
Reference PlanesSagittal PlaneAlso known as a side view.
BORDER MOVEMENTS IN SAGITTAL PLANEItems of interest:>Centric Relation>Hinge axis movement>MaximumIntercuspation>Edge-to-edge incisal>Maximum Protrusion>Maximum Opening
BORDER MOVEMENTS IN SAGITTALPLANECRC (Centric Relation Contact) will see the condyles in theglenoid fossa and closure of the mandible along the hingeaxis, until first tooth contact is made (many times this is inthe molar region).
BORDER MOVEMENTS IN SAGITTALPLANECO (Centric Occlusion), or Maximum Intercuspation(MI), is achieved when the patient is told to get theirmaxillary and mandibular teeth together in acomfortable, contacting position.
BORDER MOVEMENTS IN SAGITTALPLANEThe mandible willopen along the hingeaxis, with the condylesrotating within theglenoid fossa. Therotational movementwill terminate at theTerminal Hinge AxisPosition.
BORDER MOVEMENTS IN SAGITTALPLANEThe Terminal Hinge Axisis the rotationalmovement that occursfrom CR to the TerminalHinge Axis position.The condyles are rotatingcompletely within theglenoid fossa. It is areproducible andconsistent movement.
BORDER MOVEMENTS IN SAGITTALPLANEMaximum Openingdisplays the mostinferior position ofthe mandible, afterthe patient isinstructed to opentheir mouth as wideas they can.
BORDER MOVEMENTS IN SAGITTALPLANEMaximum Protrusiondepicts completecontact with the teethas the mandible iscompletely protruded,anteriorly. It is themost anterior of thepositions, whenviewed from thesagittal plane.
BORDER MOVEMENTS IN SAGITTALPLANEEdge-to-Edgecontact ofMaxillary andMandibularIncisors.Mandible isprotruded forwardfrom MI, maintainingsome type of toothcontact throughout.
BORDER MOVEMENTS IN SAGITTALPLANEProtruded contact ofMaxillary andMandibular Incisors.Mandible is continuingto protrude forwardfrom Edge-to-EdgeIncisal, maintainingsome type of toothcontact throughout.
BORDER MOVEMENTS IN SAGITTALPLANEMaximumProtrusion position.The teeth are in somedegree of contact(usually in Premolar-Canine area) andmandible is pushedforward as far aspossible.
Border Movements in SagittalPlaneMandibular Opening.Going fromMaximum Protrusionto MaximumOpening.
Border Movements in SagittalPlaneCRMIE-T-EMPMOAMOHAHATHA-MOLegend:CR = Centric RelationMI = Maximum IntercuspationE-T-E = Edge to Edge IncisalMP = Maximum Protrusion PointMOA = Maximum Opening ArcMO = Maximum Opening PointHA-MO = Hinge Axis to MaximumOpeningHAT = Hinge Axis TerminatingPointHA = Hinge Axis ArcCLRPRP = Rest Position or PosturalPosition of the MandibleCL = Chewing Loop
Reference PlanesHorizontal PlaneParallel to the Occlusal Plane or the floor
Horizontal AxisImaginary line through both condylesReference Planes
Border Movements in HorizontalPlaneCharacteristicallydescribed as a“diamond” shape.
Border Movements in HorizontalPlaneCR (CentricRelation). Firsttooth contactwhen the condylesare maximallysituated in theglenoid fossa.
Border Movements in HorizontalPlaneCO (Centric Occlusion).Maximum Intercuspationof the teeth in theHorizontal Plane.
BORDER MOVEMENTS IN HORIZONTALPLANEEdge-to-EdgeIncisal position ofthe teeth in theHorizontal Plane.