REMOVABLE PARTIAL DENTURE Flashcards
- Kennedy Classification (0.5)
Class I – bilateral edentulous areas located posterior to all remaining teeth
Class II – unilateral edentulous area located posterior to all remaining teeth
Class III – unilateral edentulous area bounded by anterior and posterior natural teeth
Class IV – a single, but bilateral edentulous area located anterior to remaining teeth
a. 6 clinical parameters for assessing potential abutment (3)
- Crown-root ratio
- Root configuration
- Periodontal ligament area
- Health and periodontium
- Endodontic consideration
- Biomechanical consideration
- Span length
- Direction of force
- Secondary abutments
- Arch Curvature
Draw the preliminary design (?)
Draw fulcrum line or rotational axis when masticatory force is acting on saddle and when saddle is being lifted (2)
d. Method of reducing stress on mucosa (2)
Extend the base of the saddle to gain more mucosal support
Use a smaller occlusal table
Indirect retainers and occlusal rests are place to gain tooth support
e. Method of reducing stress on abutment (2)
Altered cast technique
RPI/RPA
Splint the tooth
Stress breaker
f. 4 factors affecting effectiveness of Indirect retainer (2)
Indirect retainers must be positioned in properly prepared rest seats
One or more indirect retainers must be positioned perpendicular to the fulcrum line as far as possible to provide the best leverage system against dislodging forces
The effectiveness of the indirect retention will increase as the distance to the fulcrum line increases
Choose most suitable abutment tooth to place the rests for indirect retention
Rigidity of the connectors supporting the indirect retainer. All connectors must be rigid if the retainer is to function as intended.
g. 3mm high discrepancy… past paper hv (4)
Wrong jaw registration
Retake a bite registration in clinic and instruct technician remount the master cast at correct jaw relationship, adjust occlusal errors and check bite
Otto lam is wearing a denture as shown in the picture. He feels pain on biting on the left area under the denture
a. After the removal of the retained roots and some subsequent dental treatments, the dentist found that tooth 15, 17, 25, 27 and all remaining mandibular teeth can be saved. Write down the Kennedy classification for the maxillary arch. (1)
Class III Modification 2
b. The patient wants all missing teeth to be replaced. Using the correct colours, draw the
preliminary design for a cobalt-chromium denture for the maxillary arch. (3)
No more than 4 clasps, need major connector, diagonal placement of clasps
c. Write down 4 anatomical landmarks that can provide support for a mandibular free-
end saddle. (2)
Buccal shelf
Retromolar pad
Alveolar ridge
Distal abutment
d. You decided to perform a study impression for the mandibular arch of the patient. Write down instructions to the technician to request for a custom tray for the impression. (1)
Outline of the extension of the tray
Material used in impression (e.g. alginate → requires perforations on custom tray)
e. State the definition of an indirect retainer. (2)
The component of a removable partial denture that assists the direct retainer(s) in preventing displacement of the distal-extension denture base by functioning through lever action on the opposite side of the fulcrum line when the denture base attempts to move away from the tissues in pure rotation around the fulcrum line
f. Which 4 major factor determines whether an indirect retainer will be successful? (2)
Indirect retainers must be positioned in properly prepared rest seats
One or more indirect retainers must be positioned perpendicular to the fulcrum line as far as possible to provide the best leverage system against dislodging forces
The effectiveness of the indirect retention will increase as the distance to the fulcrum line increases
Choose most suitable abutment tooth to place the rests for indirect retention
Rigidity of the connectors supporting the indirect retainer. All connectors must be rigid if the retainer is to function as intended.
g. You decided to use a RPA system for the RPA clasp. Draw the features of the retentive arm of an ordinary occlusally-approaching clasp and an Aker’s clasp in relation to the undercut (o) and the survey line (–). (2)
Aker’s clasp (類似occlusal approaching C clasp)
Occlusal approaching clasp: 2⁄3 above survey line
Aker’s clasps: rigid part along the survey line
h. For the RPA systems, will you prepare guiding planes on the distal surface of tooth 35 and 44? Why? (1)
No guiding plane on RPA/RPI: if there is guiding plane → saddle cannot rotate and all stress goes to abutment and torque
a. Discuss the dilemma of path of insertion of a Kennedy Class IV RPD (4)
- The anterior alveolar ridge usually has a labial undercut
- So we need to select a path of insertion that allows the flange to be smoothly placed into the undercut and reduce dead spaces on the mesial side of the abutment
- This may involve tilting the cast heels down or selecting the path of insertion before backwards
- However, surveying at this angle tends to place the undercuts on the distobuccal side of the posterior teeth therefore if occlusal clasps are placed, it may be unsightly and may complicate design as we would need indirect retention
b. Draw a preliminary design of an upper removable partial denture (missing 12 to 23) and take the patient’s mucosal condition into account (3)
c. List the factors affecting clasp arm flexibility (2)
Cross-sectional shape: if semi-circular less flexible, if circular more flexible
Length of the arm: longer arm the more flexible
Diameter of the arm: thinner arm the more flexible
Modulus of elasticity of the material of the arm: Cobalt Chromium < stainless steel < Gold (Least flexible to most flexible)
d. Reasons for altering survey line (? marks)
- Lower survey line:
- Allow the inflexible part of the clasp to be situated lower hence may avoid occlusal interference –> which may reduce deformation and more aesthetically pleasing
- Raise survey line:
- To create a retentive undercut
- So that the retentive clasp tip can be kept away from the gingival margin to avoid food trapping and impinging soft tissue
Given a panoramic radiograph, clinical photos of occlusal view of upper and lower arch.
The patient have some teeth extracted and want to replace the teeth.
a. Kennedy Classification for upper and lower arch
Class I
Given a panoramic radiograph, clinical photos of occlusal view of upper and lower arch.
The patient have some teeth extracted and want to replace the teeth.
b. Draw a preliminary design of RPD for the lower arch (41-47, 35-37 missing (?))
Given a panoramic radiograph, clinical photos of occlusal view of upper and lower arch.
The patient have some teeth extracted and want to replace the teeth.
c. Draw the axis of rotation
i. When px bite on cookies
Given a panoramic radiograph, clinical photos of occlusal view of upper and lower arch.
The patient have some teeth extracted and want to replace the teeth.
c. Draw the axis of rotation
ii. When px bite on sticky food
Given a panoramic radiograph, clinical photos of occlusal view of upper and lower arch.
The patient have some teeth extracted and want to replace the teeth.
d. Compare acrylic and co-cr as denture base materials
High modulus of elasticity, retention of pontic, soft tissue colour, thermal
a. Missing 16, 18, 26, 28, 36, 37, 38, 46, 48. kennedy class classification for upper and lower
RPD
Maxillary arch: Class III Modification 1
Mandibular arch: Class II Modification 1
b. RPD design for lower assessment of abutment tooth clinically and radiographically
A chart showing multiple missing teeth (RPD). Apparently the questions say anterior missing.
b. Draw the denture design
A chart showing multiple missing teeth (RPD). Apparently the questions say anterior missing.
c. What is the difficulties for this denture design (anterior missing), how to solve it
a. Preliminary design for lower RPD (34-44 present, bilateral free-end saddle)
a. What is the Kennedy classification for the maxillary and mandibular teeth?(2marks)
Maxillary arch: Class IV
Mandibular arch: Class III Modification 2
b. Describe a partial denture for the maxillary teeth (draw + description). (4 marks)
c. What is the dilemma in choosing the path of insertion when making partial dentures for the maxillary teeth in this case? (6 marks)
- The anterior alveolar ridge usually has a labial undercut
- So we need to select a path of insertion that allows the flange to be smoothly placed into the undercut and reduce dead spaces on the mesial side of the abutment
- This may involve tilting the cast heels down or selecting the path of insertion before backwards
- However, surveying at this angle tends to place the undercuts on the distobuccal side of the posterior teeth therefore if occlusal clasps are placed, it may be unsightly and may complicate design as we would need indirect retention
- RPD: photos and study casts (Formative, 2005)
b. Draw a preliminary design for an upper arch RPD
Probably class IV with torus palatinus according to the answer above
- Patient requests replacement of existing denture. Given: I/O photo of upper cobalt chromium RPD.
b. What are the advantages and disadvantages of cobalt chromium alloy as a denture base material when compared with acrylic?
- C/O: multiple teeth lost, looking for replacements
- HPC:
- MH: clear
- DH: multiple extractions done
- E/O and I/O: (Refer to intra-oral photos and panoramic radiograph o Missing 18, 31, 32, 36, 37, 38, 41, 42
- Generalized horizontal bone loss
- Marked recession on 16 and 17
- 16 over-erupted
a. Draw the preliminary design of removable partial denture for this case
- C/O: multiple teeth lost, looking for replacements
- HPC:
- MH: clear
- DH: multiple extractions done
- E/O and I/O: (Refer to intra-oral photos and panoramic radiograph o Missing 18, 31, 32, 36, 37, 38, 41, 42
- Generalized horizontal bone loss
- Marked recession on 16 and 17
- 16 over-erupted
b. What are the problems associated with design of removable partial denture with free end saddle? (5)
- A middle aged lady requested replacement of missing teeth with RPD
Intra-oral photographs:
- missing 11, 12, 21, 22, 31, 32, 34, 41, 42, 43, 44
- 36, 46 crowned (stainless steel crown)
b. What are the problems associated with the path of insertion of the maxillary denture? (8)
- A middle aged lady requested replacement of missing teeth with RPD
Intra-oral photographs:
- missing 11, 12, 21, 22, 31, 32, 34, 41, 42, 43, 44
- 36, 46 crowned (stainless steel crown)
c. Draw the preliminary design for the upper and lower removable partial denture for the patient. (10)
Given: panoramic radiograph. Generalized horizontal bone loss Multiple missing teeth: 18, 16, 24, 25, 26, 27, 38, 31, 41, 42, 48 Periapical radiolucency, Furcation involvement , Tilting
b. No extraction is required. Draw the preliminary design for an upper removable partial
denture for the patient.
Given: an upper mirror shot showing a denture made in China no clasps or rest seats, some crowns are present.
e. How would you select the prosthetic tooth?
Information given: A faulty RPD Design of upper arch of replacement of 21,22,23
Discrepancy: Major connector: lingual bar
Retention: only recriprocal arm present on 17 and 27. No clasp. Support: absence of rest seat to support saddle.
Indirect retention (cingulum rest on 23 and molars) not properly positioned.
c. Draw your preliminary design. (3)
Information given: A faulty RPD Design of upper arch of replacement of 21,22,23
Discrepancy: Major connector: lingual bar
Retention: only recriprocal arm present on 17 and 27. No clasp. Support: absence of rest seat to support saddle.
Indirect retention (cingulum rest on 23 and molars) not properly positioned.
d. What are the concerns of selection of path of insertion in this case? (5)
- Clinical photo presented the lower occlusal view. Missing 36,37,38,46. Mesially tilted 47. Big DO amalgam on 45. (Summative, 2014)
a. Draw the preliminary design of the RPD (5)
