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Placing the Mn in a retruded path of closure usually results in: (meaning you stop at Retruded Contacts)Increased VDO, increased horizontal overlap (of incisors?), and decreased vertical overlapIn a retruded contact position, the Mx central does not contact any toothTerminal Hinge AxisThe center of rotation for the mandible when it opens from retruded contact positionRest (postural) position of MnMuscle guided – occurs when muscles of mastication are in tonic equilibriumDetermined exclusively by the behavior of the mandibular musculatureUsually there is no teeth contactOccurs the neuromuscular system has the least amount of activityUsual reflex is the tonic stretch reflex of Mn elevators (myotatic reflex)If the mandible were forced into CR from the rest position, the pt’s reflex neuromuscular defense would resist the applied forceFreeway Space or Interocclusal distanceResults from Rest Position of the MnWhen mandible is at physiological rest, the space that exists between the teeth, (should be no contact)Averages between 2-6mmAll 8 muscles of mastication plus supra and infrahyoids are in equilibriumAngle Classes of Occlusion*Determined by MB cusp of Mx M1Class I (70%)*MB of cusp line up with MB grooveIn terms of cusp/fossa relationship, the DB cusp of the Mn M1 rests in the central fossa of Mx M1Mx centrals overlap Mn centralsMx canine lies between Mn canine and PM140
Mn posteriors are positioned more lingually & mesially than Mx posteriorsMx posteriors are positioned more facially & distally than Mn posteriors (hey, it was a question)Which may occur in class I ptANSWER was NONE of these:Cross tooth balanceBilateral tooth contacts in excursivesPosterior tooth contacts in protrusive movementsIf you move from a postural position to ICP, you will be using the temporalis (last bit of closure)Class II (25%)*MB cusp between Mn M1 & PM2Mn incisors occlude even more posteriorIn a protrusive movement (in a Class II relationship), Mn canines articulate w/ canines, if you are thinking Class II shift backMn PM1 lies between Mx PM1 & PM2Mx canine is mesial to Mn canineMB cusp of Mn M2 would articulate in the central fossa of the Mx M2, NOT the normal marginal ridge areasIncrease/Decrease Condylar Distance, OR Increase/Decrease of Bennett AngleOne of these 2, game time decisionClass III (<5%)*MB cusp falls between Mn M1 & M2Chin protrudes Mn incisors overlap anterior to Mx incisorsA patient w/ a true or pseudo-Class III (Angle) occlusal relationship has no incisal guidanceAs the Mn retrudes, the Mx laterals contact Mn canines & lateralsIn a Class III malocclusion, the MB cusp of Mn M1 occludes in the mesial fossa of Mx PM2Mx canine is distal to Mn canineOften found when Mn arch is larger than Mx archGuiding cusps = Balancing = Non-supporting = Non-centric = ShearingMand Lingual, Max BuccalSupporting cusps = Working = Stamp = Centric (NOTE: This changes with posterior crossbite pts)Mn Buccal, Mx Lingual