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5th year final - all cards combined > Fixed Prosthodontics > Flashcards

Fixed Prosthodontics Flashcards

1
Q

What is a dental articular?

A

A hinged mechanical device to which maxillary and mandibular casts are attached, and which is intended to reproduce as closely as possible the relationship of patient’s maxilla to mandible in RCP or ICP.

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2
Q

Why use articulators?

A
  1. Diagnostic study casts during treatment planning
  2. Sometimes may facilitate the laboratory technician in making appropriately shaped crowns, bridges and dentures with functional occlusal schemes.
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3
Q

What are the types of articulators?

A
  1. Simple hinge (plane line)
  2. Average value (free plane)
  3. Semi adjustable
  4. Fully adjustable
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4
Q

What is this?

A

Simple hinge articulator
- equivalent to holding casts in your hand
- Occlusal relationship only correct when casts are together
- Opening arch of casts is determined by the hinge design and is the same for all casts mounted on this device.

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5
Q

What is this?

A

Average value articulator

  1. sufficiently accurate for reproducing ICP
  2. OK for posterior restorations where there is obvious guidance from other teeth
  3. Complete removable prostheses – balanced articulation
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6
Q

what is this?

A

Semi adjustable

  • Mandibular condyle
  • Used for fixed prostheses work often
  • Multiple units
  • Re-organised occlusion
  • Group functions
  • Anterior guidance
  • Occlusal analysis
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7
Q

What is the terminal hinge axis?

A

An axis through both condyles when they are in the most superior and posterior unstrained position in the glenoid fossa

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8
Q

What is this movement known as?

A

Posselt’s envelope of movement

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9
Q

According to the Posselt’s envelope of movement the RCP (retruded cuspal position) sits posteriorly to the ICP (intercuspal position) by how much?

A

1 mm posteriorly, also more inferior to the ICP

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10
Q

The anterior position will allow for the central incisors to do what?

A

Come edge to edge

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11
Q

what does the MO stand for on the Posselt’s envelope of movement?

A

Maximum opening

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12
Q

When the patient postures forward, from a retruded position or an intercuspal position, the condylar head moves down against the articulator eminence, it does this with an angle called the?

A

Condylar angle, this is different in everybody which is dependent on your anatomy

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13
Q

Prior to preparing teeth for laboratory fabricated restorations you must determine whether there is;
1. Pain from TMD
2. Unexplained facial pain
3. Chronic dental pain
4. Discomfort from mobile teeth

A
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14
Q

Occlusal vertical position = OVD

A
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15
Q

Occlusal facial height = OFH

A
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16
Q

Free way Space = the difference between the postural position – OVD

A
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17
Q

What is the retruded position?

A

When the condyle is in its most superior, anterior position within the glenoid fossa (terminal hinge axis position) and the mandible is elevated, the first tooth contact position is termed the RCP, CR, CRCP, RAP or ligamentous position.

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18
Q

. Why would you use a facebow recorder?

A

To allow casts to be mounted on a semi/fully adjustable articulator

19
Q

Why would you use a semi adjustable articulator?

A
  • To allow for relationship of the casts to be visualised in a number of functional positions during planning stage
  • To allow the relationship to be changed by waxing up or fabrication of restoration
20
Q
  1. What does a facebow record?
A

Relationship of the maxillary teeth to the condylar head in a retruded position ie; when it sits within the glenoid fossa in a posterior superior position

21
Q
  1. What are the steps taken in completing a facebow record?
A
  • Using bite-fork (angle goes towards pts right) on upper part place wax
  • Place on the upper teeth and ensure its in centre and press against the upper teeth (no biting) giving an occlusal indentation
  • Use reference plane location on the incisal edge of the 3s and the it will make the reference point on the side of the face
  • Use self centering earbow and adjust to place. Place the bitefork and ask the pt to hold it ensuring it is held in the right place
  • Join the bite-fork and earbow using the jig
  • Follow the number on the jig. Numbers should be the right way round and facing youself.
  • bring down the earbow and fit int to the correct hole and secure. Then the earbow adjusted and engages. Tigthen the screws, before doing so, ensure all is in the right place
22
Q
A
23
Q
  1. How are casts mounted on the articulator?
A
  • Facebow and interocclusal record
  • Facebow: Calliper like device that records the relationship of the maxilla to the terminal hinge axis (position of condyle)
  • Bite fork: to record position of teeth (maxillary teeth)
  • Bow: to link bow and bite fork
  • Pointer for 3rd reference point: to align teeth to horizontal axis (Frankfurt plane)
24
Q
  1. What factors need to be considered when prescribing restorations?
A
  • Pain from TMD
  • Unexplained facial pain
  • Chronic dental pain
  • Discomfort from mobile teeth
25
Q

Freeway space (FWS)

A

2-4mm; 1-9mm

26
Q
  1. How do you measure the FWS?
A

Postural position. Rest position – OVD = FWS

27
Q
  1. What is used to measure the OVP?
A

Willis gauge, mirror handle, point on soft tissue or gingival margins and dividers

28
Q
  1. What is it called when there is a comfortable closed position where max. no. of natural teeth meet?
A
  • ICP
  • Centric occlusion (CO)
  • Maximum intercuspation
  • IP
  • Muscular position (artificial teeth present)
29
Q
  1. What is a returded position known as?
A
  • Centric relation (CR)
  • Centric relation contact position (CRCP)
  • Retruded contact position (RCP)
  • Retruded axis position (RAP)
  • Ligamentous position (ligaments determine how condylar head sitting in fossa)
30
Q
  1. Centric relation
A

A maxillomandibular relationship. Independent of tooth contact, in which the condyles articulate in the anterior-superior position against the posterior slops of the articular eminences; in this position, the mandible is restricted to a purely rotary movement; from this unstrained, physiologic, maxillomandibular relationship, the patient can make vertical, lateral or protrusive movements; it is clinically useful, repeatable

31
Q
  1. Retruded position
A

This is when condyle is in its most superior anterior position within the glenoid fossa (terminal hinge axis position) and the mandible is elevated, the first tooth contact position is termed the RCP, CR, CRCP, RAP, or ligamentous position

32
Q
  1. Definition of retruded contact
A

Contact of a tooth/teeth along the retruded path of closure; initial contact of a tooth/teeth during closure around a transverse horizontal axis; comp centric occlusion

33
Q
  1. What is the relationship of ICP and RCP?
A

Mandible closes around the terminal hinge axis and then is guided by the teeth (with an anterior slide of 1-2mm) into ICP. When conforming to the present occlusion, restoration should not interfere with this anterior slide

34
Q
  1. TMJ
A
  • Surrounded by connective tissue capsule
  • Intrinsic and extrinsic ligaments
  • Innervated by V3
  • Supplied by superficial temporal branches of external carotid artery and drained by the vein
  • Muscles of mastication – jaw opening and closing
35
Q
  1. Protrusive excursion
A
  • Incisor/canine guidance or posterior guidance
  • Class II. Div II. Increased overbite – when trying to open it will hinge open
  • Class II. Div I. incisal relationship – when mandible moves forward, it’s the posterior teeth that guide the movement of the mandible along with the muscle and joint rather than the incisors and canine
  • Reverse overjet – if mandible slide forward, posterior with joint and muscle guide the mandibular path
36
Q
  1. Lateral excursion
A
  • Canine guidance
  • Group function
37
Q
  1. What is the function of intercuspal position (ICP)?
A
  • Occlusal phase of mastication (max bite force 40-200N)
  • Aids jaw stabilisation and support of soft tissues for oral seal during swallowing (2400 times/day average) (helpful in the elderly during swallowing)
  • Contributes to appearance
38
Q
  1. Why is ICP important for indirect restoration and prostheses?
A
  • Natural teeth have hard but brittle enamel supported by less mineralised dentine.
  • They are supported by the periodontal ligament within the alveolar bone.
  • The Periodontium is usually loaded axially in ICP.
  • ICP is the position gained at the end of the chewing cycle ie. Maximum force is exerted
  • Teeth with crowns may have brittle porcelain (strengthened by mental substructure); luting cement
  • Excessive forces should be avoided to minimise failure
  • Avoid accelerated wear of opposing teeth, tooth migration and tooth mobility
39
Q
  1. What is recommended to carry out before fabricating crowns?
A

Occlusal examination.
- Clinically and/or with casts. Articulating paper or occlusal wax and radiographs

40
Q
  1. What is observed with the occlusal examination?
A
  • Maxillary/mandibular relationship in static ICP, especially in area of proposed intervention (is there space for restoration?)
  • Is the position reproducible/correct?
  • How different is it to RCP?
  • Is the FWS within the normal range?
  • Is there any function relationship to be considered?
41
Q
  1. Any parafunctions/occlusal problems?
A
  • Are there any signs of grinding?
  • Evidence of habits – sucking, pens etc
  • Any failed restorations? Why?
42
Q
  1. What factor are you looking at for lateral guidance?
A

Does the canine guide the mandible laterally (canine guidance) or do many posterior teeth (group function)
- Is it balanced side contacts?

43
Q
  1. Protrusive movements
A

When tooth/teeth is/are involved in anterior or lateral guidance (eg. Palatal surface of incisor or canine), then articulated models with a customised incisal guidance table may be advantageous

44
Q
  1. How do you transfer this clinical information to the lab?
A
  • Facebow recording
  • Static movements recorded
  • Articulators
  • Limitations are always present

5th year final - all cards combined (174 decks)

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