MDS PREP
Which class of RPD is characterized by the absence of an axis of rotation?
1) Class I
2) Class II
3) Class III
4) Class IV
Prosthodontics Answer: 3
Class III RPDs do not have a significant axis of rotation due to their design, which allows for better load distribution across the remaining teeth compared to Class I and II RPDs.
The first step in surveying the casts for RPD is
1) Establishment of guiding planes
2) Establishment of undercuts for retention
3) Establishment of tooth contour for aesthetics
4) None of the above
Prosthodontics
Answer: 1
The initial step in surveying casts for an RPD is the establishment of guiding planes. These planes are essential for determining the path of insertion and removal of the denture, which in turn affects the overall stability and function of the prosthesis. Once the guiding planes are established, other steps such as identifying undercuts for retention and aesthetic considerations can be addressed.
Which of the following is not desirable in complete denture occlusion
1 Minimum occlusal contact areas for reduced pressure in comminuting food
2 Functional lever balance by favorable tooth to ridge crest position
3 Balanced occlusal contacts bilaterally for all eccentric movements
4 Anterior incisal contacts during all posterior masticatory functions and para
function
Prosthodontics
Answer: 4
Explanation: Anterior incisal contacts during posterior
masticatory functions are not desirable because they can lead to instability and
improper function of the complete denture. Ideally, posterior teeth should
provide the primary occlusal contacts during chewing, while anterior teeth
should not interfere with these functions. This helps maintain a balanced
occlusion and prevents excessive wear or damage to the denture.
The best criterion for teeth selection is
1. Past photographs
2. Pre extraction records
3. Study models
4. None of the above
Prosthodontics
Answer: 2
Pre-extraction records provide the most accurate information regarding the size, shape, and position of the teeth before extraction, making them the best criterion for selecting replacement teeth in prosthodontics.
Closest speaking space in normal jaw relations is approximately
1. 0 to 1.5 mm
2. 1.5 to 3 mm
3. 3 to 6 mm
4. 6 to 9 mm
Prosthodontics
Answer: 2
Closest speaking space in normal jaw relations is approximately 1.5 to 3 mm.
When recording jaw relations, the danger of displacing the baseplates can be
minimized by
1. fabricating wax occlusal rims
2. lining the baseplate with acrylic resin
3. fabricating compound occlusal rims
4. lining the baseplate with zinc oxide-eugenol impression paste
Prosthodontics
Answer: 4
Explanation: Lining the baseplate with zinc oxide-eugenol impression paste
provides a more stable and accurate fit during jaw relation records. This
material can help capture the contours of the underlying tissues and minimize
movement of the baseplate, thus reducing the risk of displacing it during the
recording process. The other options may not provide the same level of
stability.
A properly designed rest on lingual surface of a canine is preferred to a rest on incisal surface because
1) Less leverage is exerted against the tooth by lingual rest
2) Enamel is thicker on lingual surface
3) Visibility and access is better on lingual surface
4) None of the above
Prosthodontics
Answer: 1
a properly designed rest on the lingual surface of a canine is preferred because it exerts less leverage against the tooth compared to a rest on the incisal surface (option 1). This is important for maintaining the integrity of the tooth and preventing potential damage or displacement.
The following aslo serves in guiding path of insertion and path of removal along with guiding planes
1) Minor connector
2) Occlusal rest
3) Major connector
4) Clasps
Prosthodontics
Answer: 1
While guiding planes are the primary elements that dictate the path of insertion and removal, the minor connector also plays a role. The minor connector helps in the overall stability and retention of the RPD by linking the major connector to the abutment tooth and distributing the forces more evenly across the denture base. However, its primary function is not to guide the path of insertion and removal as much as it is to provide additional support and strength to the RPD.