Occlusion for Fixed Prosthodontics Flashcards
occlusion is a critical factor for:
all dental restorations and for the health and longevity of teeth and intraoral structures
if a patient has orthodontically ideal angles class I occlusion this does not mean that:
the patient has optimal occlusal contacts, optimal condyle/mandibular position, and ideal/optimal contacts in excursive movements
patients may have a less than ideal occlusion however it may still be:
- a functionally acceptable occlusion
- a physiologically acceptable occlusion
what do you need to assess to see if treatment is required
- the masticatory system for evidence of pathology - tooth wear, tooth mobility, TMJ dysfunction, muscle dysfunction
- adaptive capacity of a patient
what is the optimal functional occlusion
mutually protected occlusion
what is mutually protected occlusion
- multiple, even, bilateral, simultaneous occlusal contacts of the posterior teeth in MIP with the mandible is CR position
- MIP and CR are coincident
describe the anterior teeth in mutually protected occlusion
anterior teeth exhibit lighter occlusal contacts as compared to posterior teeth in MIP
describe posterior teeth in mutually protected occlusion
posterior teeth are loaded axially in MIP
describe excursive movements in mutually protected occlusion
- canine guidance/anterior guidance occurs
- the anterior teeth disclude the posterior teeth in excursive movements to protect the posterior teeth from off-axis loading
the TM joints are in optimum, orthopedically stable joint position when the mandible is in:
centric relation
which teeth withstand the majority of the load in MIP in mutually protected occlusion
the posterior teeth
which teeth can tolerate axial loading and why
posterior teeth to protect the anterior teeth in MIP
which teeth can tolerate lateral forces and why
anterior teeth because they are further away from the fulcrum and the loads are less
evaluation of occlusion:
- is required at all phases of the fixed pros treatment
- better results if the evaluation of occlusion has been done at all stages
when is evaluation of occlusion done
in conjunction to clinical examination and articulated casts
what cast is articulated using a facebow record
maxillary
what are the 2 positions to articular mandibular casts
- CR
- MIP
what is the purpose of a facebow
orient the maxillary cast to the rotational axis in three planes
describe the kinematic facebow
- the most accurate
- locates the true hinge axis
- requires training, elaborate instruments and more time
describe the arbitrary facebow
- locates an arbitrary hinge axis by using anatomical landmarks
- less accurate
- requires less complicated instruments and less time
what are the benefits of using a facebow
results in the path of opening and closure being the same on articulator as intraorally
describe CR
the position of the mandible in which the condyles are in the most superior and anterior position in the articular fossae resting against the posterior slopes of the articular eminences with the articular discs interposed
recording CR on a dentate pt requires:
an anterior deprogrammer
describe the articulation of casts in CR
- interocclusal records
- the record is made at increased OVD
- avoid deflective tooth contacts
if an accurate CR record is made, then the ________ can be achieved on the articulator
MIP position
describe MIP
- a position in which the maxillary and mandibular teeth make maximum surface contact with each other
- the mandible is elevated as superiorly as possible in the sagittal place
- habitual closing position
for most patients: are MIP and CR coincident
no
should an interocclusal record be used to articulate the dx casts in MIP
no
what is the importance of accurate articulation
the casts that are mounted on the articulator need to exhibit the same occlusal relation as the teeth do intraorally
when do you articulate casts using CR record
- diagnose occlusal disease
- completely edentulous patients
- partially edentulous patients
- dentate patients to receive extensive fixed prosthodontics restorations
what occlusal disease constitutes using CR record when articulating casts
- TMD
- occlusal equilibration
- splint
- orthodontic
- orthognathic surgery
what partially edentulous patients use articulates casts in CR record
when there are few teeth remaining
- a stable MIP is not present
what dentate patients receiving fixed pros restoration require articulating casts in CR
- occlusion will be altered completely
- the restorations will be made at an increased OVD
- kinematic facebow recording necessary
describe full size articulators
- anatomic hinge axis close to that of patient
- slight different in arc of closure between patient and articulator
describe the hinge articulator
- large difference in arc of closure between patient and articulator
- centric premature contacts in restorations
condylar elements are set with:
eccentric records
opposing cusps will travel through:
groove pathways without tooth contact in excursions
- posterior teeth disclude during excursive movements
discrepancies in occlusal morphology ->
interferences on the restoration - especially on NW side
when is a full arch impression/articulation recommended:
more posterior teeth occlusal surfaces being restored
- FPDs and multiple crowns
what does a custom incisal guide table provide
a record of the lingual concavity and incisal edge length/position and therefore anterior guidance for replication when fabrication anterior indirect restorations
what happens during the occlusion treatment phase
articulate working casts
what is the purpose of articulation of the master cast/working cast
- ensure accurate tooth to tooth occlusal contacts
- verify contact of incisal pin to the anterior guide table
- accuracy of mounting is critical to create accurate occlusion on restorations
describe the material of the mounting casts
- no resistance to closure
- rigid when set
- dimensional stability/accuracy
when and how should you mount casts for patients in MIP
- for patients that have a stable MIP position
- mount casts with MIP record at OVD
what are the occlusal schemes
- mutually protected occlusion
- group function/ unilaterally balanced occlusion
- balanced occlusion/ bilateral balanced occlusion
describe group function
- as mandible moves laterally, it is guided by a group of teeth (canine, premolars and MB cusp of 1st molar) on the WS
describe balanced occlusion and what patients use this
- simulataneous contacts on both sides during lateral movements - WS and NWS - and between posterior/anterior during protrusive
- not acceptable for dentate patients
- acceptable form of occlusion for CD and RPD
why is balanced occlusion not acceptable for dentate patients
promotes tooth wear, NW side contacts are destructive
why is balanced occlusion an acceptable form of occlusion for CD and RPD
- contact on NW side can help stabilization of the removable prosthesis
how should you create the occlusal surface to ensure proper loading of the teeth
- cusps and ridges should allow even occlusal contacts with opposing teeth with forces along long axis
- non centric cusps should overlap horizontally and vertically
describe the curve of spee
- A-P curve
- cusps follow an anteroposterior curve
- steepness of curve influences the cusp heights
describe the curve of wilson
- M-L curve
- mediolateral curve
- non functional cusps shorter than functional cusps
- helps prevent interferences in lateral excursions
what are the two types of contact relationships
- cusp- fossa
- cusp- marginal ridge
where should the occlusal contacts be on the occlusal surfaces
- tripodized point contacts on cusps, fossa/marginal ridges
- buccal and lingual cusps lie along a-p lines
describe the waxing technique of proximal contact areas
- size and location are established first
- proper size: convex oval area, not pinpoint or deficient
- location: occlusal 1/3, distal: more cervically located, slightly towards facial
- should reflect the emergence profile and contour gingival to the contact area
- flat to slightly concave from contact area to CEJ
-proper space for interdental papilla
describe the waxing technique of axial surfaces
- shape buccal and lingual surfaces to follow contours of adjacent and contralateral teeth
- height of contour: buccal: cervical 1/3, lingual: middle 1/3
- emergence profile: surface apical to height of contour adjacent to gingival soft tissues. flat or straight, avoid bulky convexity in cervical region
