Removable Partial Dentures Short Answers

Removable Partial Dentures

Question 1. Contra-indication for removable partial dentures
Answer:

• Patients with macroglossia having a tendency to push the denture away
• Cannot be used in mentally retarded patients
• This should be avoided in patients with poor oral hygiene

Read And Learn More: Prosthodontics Question And Answers

Question 2. Linguoplate major connector
Answer:

• The superior border extends up to the cingulum
• Linguoplate is scalloped in between the teeth
• In the presence of large embrasures, it is made to dip down step back design
• Anteriorly, it should be supported by the rest

Linguoplate Major Connector Advantages:

• Rigid, stable
• Provide indirect retention

Linguoplate Major Connector Disadvantages:

• Food accumulation
• Decalcification of teeth
• Soft tissue irritation

Question 3. Ring clasp.
Answer:

Ring Clasp is example of a cast circumferential clasp

• Ring Clasp Indication:
  • Distal extension denture
• Ring Clasp Contraindication:
  • Soft tissue undercut
  • Buccinator’s attachment if present close to lower molar
• Ring Clasp Disadvantages:
  • Alters food flow
  • Increased tooth surface coverage
  • Cannot retain its physical qualities
  • Difficult to repair or adjust

Question 4. Objectives of surveying
Answer:

• To achieve good retention and bracing by designing the rigid and flexible components of a removable prosthesis
• Aids in marking the survey lines by determining the height of contour of hard and soft tissue areas above the undercut
• Decides the path of insertion
• Helps in deciding the areas into which the prosthesis should not extend by determining the undesirable undercuts

Question 5. Cingulum rest
Answer:

• Also known as lingual rest
• Cingulum Rest is placed on the lingual surface of a tooth
• Cingulum Rest is specially placed over maxillary canine

Question 6. Enameloplasty/ Dimpling.
Answer:

• Enameloplasty is defined as the intentional alteration of the occlusal surface of the teeth to change their form
• Enameloplasty is done to produce a retentive undercut
• Enameloplasty is a gentle depression created on the enamel surface of the abutment teeth to provide a retentive undercut It is done when abutment teeth do not provide any surface undercut
• Enameloplasty can also be done to modify the existing undercut

Question 7. Limitations of Kennedy’s classification.
Answer:

• Did not explain the length of the edentulous span or the number of missing teeth only provide number of modification spaces.
• Not enough consideration about the condition of teeth and the remaining supporting structures.
• No distinction between modification spaces which occur in the anterior segment to those of the posterior segment

Question 8. Uses of surveyor.
Answer:

• Surveying the diagnostic and primary casts
• Tripoding the cast
• Transferring the tripod marks to another cast
• Contouring wax pattern
• Contouring crowns and cast restoration Placing internal attachments and rests
• Performing mouth preparation on casts
• Surveying master cast
• Surveying ceramic veneer

Question 9. Cingulum bar
Answer:

• The Cingulum Bar is located on or slightly above the cingula of the anterior teeth
• Indications:
• Large embrasures
• Large diastema cases

Question 10. Merits of occlusal approaching clasp.
Answer:

Occlusally Approaching Clasp is easy to fabricate and repair

• Occlusally Approaching Clasp leads to less food retention
• Occlusally Approaching Clasp can be best applied in a tooth-supported partial denture
• Provides excellent support and retention

Question 11. Define  Interim Removable Denture.
Answer:

“A transitional denture may become an interim denture when all of the natural teeth have been removed from the dental arch”.

Question 12. Support for RPD
Answer:

• Support for RPD depends on
• Quality of the residual ridge
• Total occlusal load applied
• Accuracy of the denture base
• Accuracy and type of impression registration

Question 13. Height of Contour.
Answer:

Height of Contour Definition: A line encircling a tooth designating its greatest circumference at a selected position.

Height of Contour Significance:

• Height of the Contour is used as a guideline that helps in the placement of the components of the clasp
• The retentive clasp arm of the retentive arm is located above the height of contour while the retentive terminal lies below the height of the contour
• The reciprocal arm is located above the height of contour

Question 14. Guiding Planes.
Answer:

Guiding Planes Definition: “Two or more vertically parallel surfaces of abutment teeth so oriented as to direct the path of placement and removal of removable partial denture”.

Types Of Guiding Planes:

• Guide planes on abutment teeth supporting a tooth supported partial denture
• Guide planes on abutment teeth that supports a secondary distal extension denture base
• Guide planes prepared on lingual surfaces of abutment teeth
• Guide planes on anterior abutments

Functions Of Guiding Planes:

• Minimizes the wedging stresses on the abutments
• Makes insertion and removal easier
• Aids to stabilize the prosthesis against horizontal stresses
• Aids to stabilize individual teeth
• Guiding Planes improves oral hygiene
• Guiding Planes contributes to indirect retention and frictional retention

Question 15.  Internal Rests.
Answer:

• Internal Rests are large box shaped metallic extensions that function as intracoronary retainers
• Internal Rests differ from internal attachments
• Internal Rests are not pre-fabricated instead the rest seat is formed by the sound tooth structure

Question 16. Prothero’s cone theory.
Answer:

• Prothero described cone theory in 1916 to explain the basis for clasp retention
• He described the shape of the crown of premolars and molars to be equivalent to two cones sharing a common base
• The upper cone resembles the occlusal half of the tooth and the lower cone resembles the cervical half of the tooth
• A clasp tip that ends below the junction of the two cones will resist movement in the upward direction
• The degree of resistance to deformation determines the amount of clasp retention

Question 17. Combination clasp.
Answer:

A Combination Clasp is a combination of wrought wire and rigid-cast alloy

1. Combination Clasp Indication: Maxillary canines and premolars
2. Combination Clasp Contraindications: Undercut adjacent to edentulous space
3. Combination Clasp Advantages: It has thin line contact It can flex in all planes
4. Combination Clasp Disadvantages:
   • Tedious lab procedures
   • Easily breaks or distorts
   • Poor stability

Question 18. Half and Half clasp.
Answer:

• Half And Half Clasp has a retentive arm arising from one direction and a reciprocal arm arising from another
• Thus it needs two minor connector
  1. First attaches the occlusal rest and the retentive arm to the major connector
  2. Second, connects the reciprocal arm with or without an auxiliary rest
• Half And Half Clasp Modification:  The reciprocal arm is converted into short bar to reduce the tooth coverage
• Half And Half Clasp Advantage: It provides dual retention

Question 19. Fulcrum Line.
Answer:

• Fulcrum Line Definition: “An imaginary line around which a partial denture tends to rotate”
• Fulcrum Line Location: It is usually formed at the terminal abutment axis

Types of Fulcrum line:

• Retentive Fulcrum Line: “An imaginary line connecting the retentive points of clasp arms, around which the denture tends to rotate when subjected to forces, such as the pull of sticky foods”.
• Stabilizing Fulcrum Line: “An imaginary line, connecting occlusal rests, around which the denture tends to rotate under masticatory forces”.

Question 20. Displacing forces.
Answer:

Question 21. Group Function.
Answer:

Group Function Definition:

Group Function is multiple contract relations between the 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

Group Function Indications:

• End-on-end bite
• Anterior open bite
• Class 2 and Class 3 molar relation

Group Function Types:

1. Group Function Partial group function:
   • In this occlusion, some of the posterior teeth are able to shear the load in excursion whereas others contact only in centric relation.
2.  Anterior group function:
   • A most practical method of dis occluding
3. Group Function Advantages:
   • Efficient and comfortable
   • Distributes wear over more teeth
   • Distributes stresses over more teeth
   • Distributes stresses to teeth farther from the condylar axis
4. Group Function Limitations:
   • Not possible in all cases
   • Some arch relations do not permit it
   • Concave anterior guidance permits it whereas