REMOVABLE PROSTHODONTICS

Question 1

Which of the following is correct about the lingualised occlusion
(A) Buccal cusps of maxillary teeth tilted to contact central fossa and marginal ridge of mandibular teeth
(B) Balanced lingualised indicated for class II skeletal occlusion with skeletal crossbite
(C) Non balanced lingualised indicated for class III skeletal occlusion with skeletal crossbite
(D) Balanced lingualised utilises mandibular non-anatomical teeth

Answer 1

C)

Question 2

What are some indications for a monoplane occlusion?

Answer 2

Monoplane occlusion: Teeth on both arches have no cusps

Indication: Class II or III skeletal occlusion with normal transverse skeletal relationship
Difficulty obtaining repeatable CR (muscle incoordination)
Skeletal malocclusion (Class II or III)
Crossbite
Severely residual ridge resorption 
Aged patients → Physical limitations, poor adaptability
Poor neuromuscular control
Parafunctional habit

Question 3

List four indications for precision attachment use.

Answer 3

o Movable links in fixed movable crown and bridge work
o Stress breaker in removable free-end saddle denture and bridge
o Efficient direct retainers for RPDs (intracoronal attachments)
o Situations where sectional dentures are indicated (precision attachment used as connector)
o Intracoronal attachments are used as joining medium
o Attachments used to lock a connector assembly saddles in the opposite side of the dental arch
o Emergency attachments for extension or conversion of existing denture
o In situations where periodontal condition contraindicates use of fixed dentures
o For retention in aesthetic zone where direct retainer is undesirable
o Maintaining hybrid prosthesis

Question 4

List 3 disadvantages of precision attachments?

Answer 4

o Extensive preparation of abutment teeth to house intracoronal attachment
o Wear due to friction between metal parts lead to loosening of male part, causing …
 Excessive movement
 Risk damage to abutment tooth
o Extracoronal attachments may lead to gingival inflammation (plaque traps)
o Extracoronal attachments occupy space directly adjacent to abutment tooth, which is where replacement tooth should be positioned
o Abutment teeth MUST be restored
o Expensive

Question 5

Which of the following is false
(A) Intracoronal attachments are advantageous as they are more hygienic and direct forces parallel to long axis of tooth
(B) Extracoronal attachments are advantageous as they have a simpler path of insertion and have a degree of resilience
(C) Intracoronal attachments are disadvantageous as they require tooth preparation and are relatively rigid
(D) Extracoronal attachments are disadvantageous as they require extensive tooth preparation and lack resilience

Answer 5

D) Extracoronal actually require less tooth preparation and also have a degree of resilience compared to intracoronal

Question 6

What are the six requirements for clasp assembly?

Answer 6

1. Retention: engaging undercut
2. Support: resists displacement of prosthesis in apical direction → reciprocating arm
3. Stability: resists displacement of prothesis in horizontal direction → all framework components that are rigid, occlusal rest, reciprocal element
4. Reciprocation: each retentive terminal should be opposed by a reciprocal component
5. Encirclement: prevent movement of abutment away from associated clasp assembly → >180 degree coverage
6. Passivity: prevents transmission of adverse forces to associated abutment when prothesis complete seated → reciprocator/major connector needs to extend above survey line (reciprocator arm only activated when dislodging forces applied)

Question 7

List three features of excessive OVD and inadequate OVD?

Answer 7

•	Excessive occlusal vertical dimension 
o	Sore muscles
o	Soft tissue sore spots
o	Rapid bone resorption
o	Dentures click during speech
•	Inadequate occlusal vertical dimension 
o	Collapsed appearance
	Chin too close to nose
	Protruding jaw
o	Deep nasiolabial folds
o	Fatigue when chewing
o	Sore muscles or joints

Question 8

List 3 factors why upper complete denture may be loose

Answer 8

• Overtension in sulcuse
• Flanges too think
• Coronoid process impingement
• Post dam is too short or long
• Incorrect OVD