Occlusion Flashcards
Occlusion
Contact between teeth; Relationship between the maxillary and mandibular teeth when they approach each other (Chewing or Rest)
Intercuspation
Cusp-to-Fossa relationship of the upper and lower posterior teeth to one another
Interdigitation
Interlocking or fitting together of the cusps of opposing teeth
Stability
Each tooth interdigitates with two opposing teeth
Interdigitation Distinctions
Interdigitation is most distinct in the anterior and premolar regions; Less distinct in the molar regions
Mandibular Interdigitation
Mandibular tooth interdigitates with same tooth in maxillary arch and tooth mesial to it
Maxillary Interdigitation
Maxillary tooth interdigitates with same tooth in mandibular arch and tooth distal to it
Exceptions to Interdigitation
Mandibular central incisors and Maxillary third molars interdigitate with only one opposing tooth
Centric Occlusion
Occlusion of opposing teeth when the mandible is in centric relation; May or may not coincide with maximum intercuspation (Tooth to Tooth)
Maximum Intercuspation
Occlusal portion of the mandible in which the cusps of the teeth of both arches fully interpose themselves with the cusps of the teeth of the opposing arch
Centric Occlusion-Buccal View
Maxillary buccal cusps are in line with opposing buccal embrasure and developmental grooves
Centric Occlusion-Lingual View
Mandibular lingual cusps are in line with opposing lingual embrasures and developmental grooves
Centric Relation
Maxillomandibular relationship in which condyles articulate with thinnest avascular portion of their respective disks with the complex in anterior-superior position against the shapes (posterior slopes) of the articular eminences (with disks properly interposed); Independent of tooth contact (Bone to Disk to Bone)
Centric Relation Discernible Position
Clinically discernible when mandible is directed superior and anteriorly; Restricted to a purely rotary movement about the transverse horizontal axis
Centric Stop
Opposing cuspal/fossae contacts that maintain the occlusal vertical dimension between the opposing arches
Centric Stops
Cusp-Marginal Ride
Cusp-Fossa
Cusp-Occlusal Embrasure
Line of the Central Groove
Rolling in of the outer inclines of the supporting cusps places them under/over the line of the central groove of the opposing arch
“Closure Stoppers”
Posterior teeth
Posterior Occlusion-Passive
Only excursive contacts should be on anterior teeth
Mutually Protected Occlusion
Posterior teeth protect the anterior teeth in CO and help prevent excess loading to the TMJ’s; In protrusive movement the incisors protect the canines and posterior teeth; In lateral excursions the canines protect the incisors and posterior teeth
Supporting Cusps
Contact opposing centric stops and do most of the grinding during mastication; Maxillary-Lingual cusps; Mandibular-Buccal cusps
Non-Supporting Cusps
Overlap supporting cusps-0.5 to 1.0mm space in centric occlusion between the supporting and non-supporting cusps; Maxillary-Buccal cusps; Mandibular-Lingual cusps
Protection of Soft Tissues
Non-Supporting Cusps:
Maxillary buccal cusps overlap opposing mandibular buccal cusps (Cheeks out of way during mastication); Mandibular lingual cusps overlap opposing maxillary lingual cusps (Tongue out of way during mastication)
Anterior Guidance
Functional relationships of maxillary and mandibular anterior teeth during excursive movements
Posterior Disclusion
Anterior guidance protects posterior teeth
Greatest Anterior Guidance Effects
Premolar region
Greatest Condylar Guidance Effects
Molar region
Prevention of Excessive Range of Motion
Anterior Guidance; Protects TMJ’s by limiting excursive movements
Anterior Teeth Protection in Anterior Guidance
Protected during excursive movements by distance from temporomandibular joints (Forces close to the joints are much greater)
Canine Guidance/Cuspid Rise/Canine Protected Articulation
Form of mutually protected articulation in which vertical and horizontal overlap of canine teeth disengage posterior teeth in excursive movements of the mandible
True Friend to Restorative Dentist
Cuspid Rise- Helps prevent working and balancing interferences
Canine Eminence
Thick facial plates of bone that provide additional protection from the forces on the canines
Longest Roots in mouth
Canines
During lateral excursion, only teeth to touch on working side
Cuspid rise- Canines
Group Function
Multiple contact relations between maxillary and mandibular teeth in lateral movements on the working side whereby simultaneous contact of several teeth acts as a group to distribute occlusal forces (Outer inclines of mandibular buccal cusps contact inner inclines of maxillary buccal cusps)
During a lateral excursion, on working side
Buccal cusps contact along with the canines
Patient with group function
Restorative dentist may need to give special consideration to condylar guidance; Use of protrusive and lateral records to set superior walls may not be adequate for setting condylar guidance on articulator
Group Function- Occlusal Scheme
Large restorative cases with group function, some clinicians want no working contacts on distobuccal cusps of first molars and buccal cusps on second molars
Steering wheel of Occlusion
Anterior teeth
Rotation
In initial phase of opening from centric relation, condyles hinge or rotate about fixed axis
Hinge Axis
Axis runs through each condyle, Can be determined and recorded for diagnostic and restorative purposes
Posselt’s Diagram, Hinge opening
B-CR, Hinge or rotary opening occurs for first inch or 20-25mm from centric relation
Translation
During translatory opening, condyles translate or slide down and forward on articular eminences; May slide over the crests of articulator eminences at maximum opening
Posselt’s Diagram, Translation
B-E, Translation of condyles normally continues until there has been 40-60mm total opening
Right Lateral Excursion Working/Non-Working
Working side: right
Non-working/Balancing side: left
Molar Relationships-Working Side
On working side, mesiolingual cusps of maxillary molars track out the lingual grooves of mandibular molars; distobuccal cusps of mandibular molars track out buccal grooves of maxillary molars
Molar Relationships- Non-Working Side
On nonworking side, mesio-lingual cusp of maxillary first molar tracks over disto-buccal groove of mandibular first molar; Cusp tracks in disto-buccal direction
Working Position
Mesiodistal position of non-supporting cusps accommodates working movements; These cusps aligned with opposing embrasures and developmental grooves in working position
Left Lateral Excursion- Orbiting/Rotating Condyle
Left Lateral Excursion: Right condyle = Orbiting condyle, Left condyle = Rotating condyle
Orbiting Condyle
Moves downward, forward and medially; Condyle on non-working or balancing side
Rotating Condyle
Moves laterally, may move forward or backward and upward or downward; Condyle on working side
Protrusive Movement
Condyles slide forward and downward on articular eminences; Mandibular incisal edges are sliding down the lingual surfaces of the maxillary incisors
Condylar Guidance
Functional relation of the hard and soft tissues of the temporomandibular joints which controls mandibular movements
Articulator Eminence VS. Cusps
The flatter the articulator eminence, the shorter the cusps; The steeper the articulator eminence, the taller the cusps
Anterior Guidance VS. Condylar Guidance
Anterior Guidance should be equal to or greater than Condylar Guidance; this keeps the condyles working against posterior slopes of articular eminences during excursive movements; Distraction of condyles due to CR or excursive interferences can be harmful to temporomandibular joints
Determinants of Occlusion
Right and left temporomandibular joints, occlusion of permanent dentition and neuromusculature; Anterior teeth=Active determinants, Posterior teeth=Passive determinants
Physiologic Rest Position/Postural Rest Position/Clinical Rest Position
Postural position of the mandible when the head is in an upright position and the associated muscles are in a state of minimal contraction
Freeway Space
Distance between the occluding surfaces of the maxillary and mandibular teeth when the mandible is in the physiologic rest position; Normal amount of free way space in dentulous dentition is 2-4mm
Malocclusion
Any deviation from a physiologically acceptable contact between the opposing dental arches
Occlusal Prematurity
Any contact of opposing teeth that occurs before planned intercuspation
Primary Occlusal Traumatism
Abnormal forces on normal supporting structures; When prematurities and interferences are removed, tooth can stabilize in several days
Fremitus
Functional mobility
Number one sign of Occlusal Traumatism
Mobility
Premature Contact
Signaled to brain; Brain instructs muscles of mastication to bring teeth into “new” maximum intercuspation
Occlusal Interference
Any tooth contact that inhibits remaining occluding surfaces from achieving stable and harmonious contacts; An occlusal contact that disrupts the smooth excursive movements of teeth against each other; Presence of occlusal interference can result in disclusion of anterior guidance
Occlusal Adjustment
- any change in occlusion intended to alter occluding relation 2. any alteration of occluding surfaces of teeth or restorations
Articulator
A mechanical instrument that represents temperomandibular joints and jaws, to which maxillary and mandibular casts may be attached to stimulate oralmandibularmovements
Facebows
Relate maxilla to an arbitrary hinge axis; If dentist is going to alter vertical dimension, may be necessary to use kinematic facebow to record true hinge axis
