ORE Part 2 Prosthodontics — Questions and Answers
Question 1: When constructing a complete denture, what determines the correct occlusal vertical dimension (OVD)?
- The height of the residual ridge only
- The patient's existing dentures always
- Assessment of freeway space, facial proportions, phonetics, and patient comfort (Correct answer)
- A standard measurement of 65mm for all patients
Correct answer: Assessment of freeway space, facial proportions, phonetics, and patient comfort
The correct OVD is established by assessing multiple factors: the freeway space (2–4mm between the rest vertical dimension and OVD), facial proportions (lower facial height), phonetic tests (closest speaking space during 's' sounds), patient comfort, and the pre-extraction records if available. No single method is reliable alone.
Question 2: What is the primary purpose of a facebow record in prosthodontic treatment?
- To measure the size of the patient's teeth
- To transfer the relationship of the maxilla to the hinge axis of the mandible to a semi-adjustable articulator (Correct answer)
- To record the shade of the patient's existing teeth
- To take an impression of the soft tissues
Correct answer: To transfer the relationship of the maxilla to the hinge axis of the mandible to a semi-adjustable articulator
A facebow records the spatial relationship of the maxillary arch to the transverse hinge axis (or an arbitrary point near the condyles) and transfers this to a semi-adjustable articulator. This ensures that the arc of closure on the articulator mimics the patient's jaw movements, improving the accuracy of the occlusal scheme.
Question 3: A patient wearing a complete upper denture complains of gagging. Which denture feature is most commonly responsible?
- The denture is too short posteriorly
- The posterior border of the denture extends too far beyond the vibrating line onto the soft palate (Correct answer)
- The teeth are set too far lingually
- The denture base is too thin
Correct answer: The posterior border of the denture extends too far beyond the vibrating line onto the soft palate
Over-extension of the posterior palatal seal area beyond the vibrating line (junction of hard and soft palate) is the most common denture-related cause of gagging. The soft palate is highly sensitive, and contact with the denture triggers the gag reflex. Correct identification of the vibrating line during impression taking is essential.
Question 4: Which type of connector is most appropriate for a Kennedy Class I removable partial denture (bilateral free-end saddle)?
- Ring connector
- Full palatal plate
- Anterior-posterior palatal bar design with indirect retention (Correct answer)
- Single midline palatal bar
Correct answer: Anterior-posterior palatal bar design with indirect retention
Kennedy Class I (bilateral free-end saddle) RPDs benefit from an anterior-posterior palatal bar or palatal strap design that provides rigidity, cross-arch stabilisation, and indirect retention. The indirect retainers (rests anterior to the fulcrum line) resist the distal extension saddle lifting away from the ridge during function.
Question 5: What is the function of a post dam (posterior palatal seal) in a complete upper denture?
- To make the denture more comfortable to wear
- To create a seal at the posterior border to aid retention by preventing air entry under the denture (Correct answer)
- To prevent the patient from gagging
- To support the soft palate during swallowing
Correct answer: To create a seal at the posterior border to aid retention by preventing air entry under the denture
The post dam creates a compressive seal between the denture and the soft tissues at the junction of the hard and soft palate. This prevents air from entering beneath the denture, which would break the vacuum-like retention. It is formed by slightly overcontouring the posterior border area of the denture into the compressible tissue of the vibrating line.
Question 6: When selecting teeth for a complete denture, what guide should be used to determine the width of the upper anterior teeth?
- The patient's age only
- The inter-alar width (distance between the sides of the nose) as a guide for the combined width of the six upper anterior teeth (Correct answer)
- The width of the mandibular arch
- A standard size for all patients
Correct answer: The inter-alar width (distance between the sides of the nose) as a guide for the combined width of the six upper anterior teeth
The inter-alar width (distance between the outer edges of the alae of the nose) provides a useful guide for the combined width of the six upper anterior teeth. While not exact, this anthropometric relationship helps in selecting appropriately sized teeth when pre-extraction records are unavailable.
ORE Part 2 Prosthodontics
When constructing a complete denture, what determines the correct occlusal vertical dimension (OVD)?