RPD
The difference between an RPI and an RPA
I-bar retentive arm and Aker's Clasp retentive arm.
(Gingivally and Occlusally approaching)
this high-strength, stabilised ceramic is commonly CNC-milled to fabricate fixed crowns and bridges
What is Zirconia
This term describes the complete absence of natural teeth in an individual.
what is edentulism?
In a Kennedy Class I RPD, this component is positioned anterior to and as far as practical from the fulcrum line to resist lifting of the distal-extension bases.
What is an indirect retainer?
This additive manufacturing technology uses a digital projector to cure an entire layer of photopolymer resin simultaneously.
What is Digital Light Processing (DLP)?
The U-Shape or Horseshoe Major Connector. Would use if patient had excessive gag reflex or palatal tori that disrupts design.
What is the difference between type IV and V gypsum?
Type IV - <0.1% expansion rate. accurate, economical, easy to handle. Susceptible to abrasion.
Type V - approx 0.3% expansion rate. (to compensate for alloy shrinkage). High strength. Expansion requires greater control.
what are the seven domains of the Oral Health Impact Profile (OHIP-14)
Functional → Physical Pain → Psychological Discomfort → Physical Disability → Psychological Disability → Social Disability → Handicap
These prepared, approximately parallel surfaces on abutment teeth help establish a consistent path of insertion and improve RPD stability.
What are guiding Planes?
This direct metal additive manufacturing method uses a high-energy laser to melt successive layers of cobalt-chromium powder to fabricate an RPD framework.
What is Selective Laser Melting (SLM)?
the difference between Support, Retention, and Stability. Give one component for each.
Support resists tissueward movement under occlusal loading. (Rests)
Retention resists dislodgement. (direct retainers)
Stability resists horizontal displacement. (rigid connectors/ bracing components).
A crown produced using five-axis CNC milling has poor internal adaptation. Explain why having more axes does not guarantee a more accurate restoration. Identify 3 possible errors.
This orthodontic index uses both a Dental Health Component (DHC) and an Aesthetic Component (AC) to classify treatment need.
What is the Index of Orthodontic Treatment Need (IOTN)?
When alloys contract during solidification and cooling. Investment expansion is used to compensate for that contraction
What is shrinkage compensation?
This hybrid manufacturing approach uses a digitally printed sacrificial resin pattern, followed by investment, burnout and conventional metal casting.
What is 3D-printed pattern investment casting?
Why does a Class I RPD rotate under occlusal force?
these two manufacturing-related problems can compromise the accuracy or surface quality of a CNC-milled crown, even when the original digital design is correct.
What are milling-tool wear and incorrect toolpaths during fabrication?
A 13-year-old patient receives a Dental Aesthetic Index (DAI) score of 33. Identify the severity classification and corresponding orthodontic treatment recommendation.
What are severe malocclusion and highly desirable orthodontic treatment?
A DAI score of 31–35 represents severe malocclusion. A score of 36 or above represents very severe malocclusion, for which treatment is classified as mandatory.
How does induction melting work?
what is the changing magnetic field induces circulating electrical currents called eddy currents. Electrical resistance and other electromagnetic effects convert energy into heat?
In a lecture study involving 540 printed resin RPD frameworks, this build angle and build-plate location generally produced the most favourable accuracy results.
What are a 45° build angle and the middle of the build plate?
Explain the Fulcrum Line and Lever Mechanics
The fulcrum line is an imaginary axis connecting the principal rests on abutment teeth, around which an RPD can rotate during functional loading or dislodgement. Lever mechanics explain how forces acting at different distances from this line produce rotational torque, which can be controlled through appropriate rest positioning, indirect retainers and stress-releasing clasp designs.
List all factors that influence retention and resistance during tooth preparation.
What is Taper, Surface area, Occlusogingival height, freedom of displacement, internal preparation features, and path of insertion?
A child experiences premature loss of a primary molar due to severe dental caries. Explain how this can lead to malocclusion in the permanent dentition, including the mechanisms involved.
When the primary molar is lost, adjacent teeth may drift or tilt into the empty space, reducing the available arch length. This can prevent the permanent successor from erupting into its correct position, resulting in crowding, displacement, ectopic eruption and altered occlusion.
A cast Co-Cr RPD framework contains localised shrinkage porosity near an abrupt sprue junction. Explain the thermal mechanism responsible and identify how sprue design should be modified to reduce the defect.
What is a localised hot spot causing delayed solidification and shrinkage porosity, corrected by smoother sprue junctions and directional solidification?
A technician assumes that printing every RPD resin pattern at 50 µm will maximise accuracy. explain why this assumption is incorrect and identify the three printing variables investigated
What is the material-dependent relationship between layer thickness and accuracy, with layer thickness, build orientation and build-plate location being the three variables?