Fundamentals of Occlusion for Fixed Prosthodontics Flashcards
— is a critical factor for all dental restorations and for
the health and longevity of teeth and intraoral structures
Occlusion
* Takes time, effort, and knowledge to assess Occlusion,
Occlusal concepts, and design appropriate occlusion for
restorations
A patient may have an orthodontically ideal
Angles Class I Occlusion. This does not mean that
the patient has (3)
optimal occlusal contacts, optimal
condyle/mandibular position, and ideal/optimal
contacts in excursive movements.
Conversely a patient with a Class II or Class III
occlusion, although not orthodontically ideal, may
in fact have
an acceptable, functional occlusion.
Patients may have a less than ideal occlusion,
HOWEVER, it may still be
(2)
a functionally acceptable occlusion
or
a physiologically acceptable occlusion
Patient’s occlusion may deviate from the ideal
(3)
- is treatment required?
- adaptive capacity of a patient
- if treatment is rendered, what is the optimal position for the joints,
muscles, and teeth
- is treatment required?
(assess the masticatory system for evidence of pathology - tooth
wear, tooth mobility, TMJ dysfunction, muscle dysfunction, etc)
MUTUALLY PROTECTED OCCLUSION
(optimal functional occlusion)
definition
anteriors
posteriors
in excursive movements:
*Multiple, even, bilateral, simultaneous occlusal contacts of
the posterior teeth in MIP with the mandible is CR position
i.e. MIP and CR are coincident.
*The anterior teeth exhibit lighter occlusal contacts as
compared to posterior teeth in MIP.
*Posterior teeth are axially loaded in MIP
*In excursive movements: canine guidance/anterior
guidance occurs
Temporomandibular Joints
The TM Joints are in an optimum, orthopedically stable joint position
when the mandible is in CENTRIC RELATION.
MUTUALLY PROTECTED OCCLUSION
* The posterior teeth
* The anterior teeth
withstand the majority of the load
in MIP, protecting the anterior teeth from high loads.
disclude the posterior teeth in
excursive movements, thereby protecting the posterior
teeth from off-axis loading.
- Posterior teeth can tolerate axial loading well so they
protect anterior teeth, which are not axially loaded, in
MIP. Anterior teeth can tolerate lateral forces in
excursive movements (off-axial loading) since they are
further away from the fulcum and the loads are less.
Evaluation of Occlusion
* Is required at
* Better results if the evaluation of Occlusion has been done at
all phases of the fixed prosthodontic treatment
(diagnosis and treatment)
all stages (even for simple prosthodontic treatments)
Evaluation of Occlusion
Diagnostic Phase
Evaluation is completed in conjunction to (2)
Clinical Examination and
Articulated Casts
Articulation of Casts
(2)
- Maxillary cast is articulated using a fabebow record
- 2 positions to articulate mandibular casts
- 2 positions to articulate mandibular casts
(2)
- Centric Relation (CR)
- Maximum Intercuspation (MIP)
Purpose of a facebow:
Orient the maxillary cast to
the rotational axis in three planes
Kinematic Facebow
This facebow is the most accurate (locates the True Hinge Axis).
Requires training, elaborate instruments, and more time.
Arbitrary Facebow
(3)
- Locates an arbitrary hinge axis by using anatomical landmarks
- Less accurate
- Requires less complicated instruments and less time.
Benefits of a Facebow Record
Using a facebow will result in the path of opening and closure
(arch of closing) being the same on articulator as intraorally.
Centric Relation 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.
Centric Relation
recording CR on a dentate pt requires an anterior deprogrammer
Articulation of Casts in CR
(3)
- Interocclusal Record(s)
- The record is made at ↑OVD
- Avoid deflective tooth contacts
Mounting Casts - CR Record
* CR record is made at an — OVD (~ 3mm)
* If an accurate CR record is made, then the
increased
MIP position can be achieved on the articulator
Maximal Intercuspal Position MIP
(also known as Maximum Intercuspation)
(4)
- This is 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 plane
- For most patients: MIP and CR are NOT coincident
- “habitual closing” position