RPD week 4

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RPD week 4
2013-07-26 00:55:24
RPD week

RPD week 4
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  1. ♦ What are the types of rests for anterior teeth?
    • Cingulum rests
    • •Incisal rests
    • •Circular concave rests
  2. ♦ What is the type of anterior rests most commonly used  for maxillary canines?
    Cingulum rest
  3. ♦ How do you prepare the positive incisal rest seats?
    • mandibular anteriors
    • 1/3-1/2 width of incisal edge and sufficient clearance
    • Concave rest seat mesiodistally
    • Convex rest seat buccolingually
    • May create greater leverage on the tooth compare to cingulum rests when used improperly and is only used when the lingual anatomy of the tooth is not appropriate
  4. ♦ What are the roles of proximal plates?
    • 1. Maintains arch integrity by producing bracing action.
    • 2. Acts as retainers by frictional contact with the parallel guide planes on the teeth.
    • 3. Guide a partial to seat along the path of insertion.
    • 4. Provides reciprocation to a retainer
    • 5. Protect against food impaction and tissue hypertrophy by adapting the guide plane at the tooth-tissue junction.
    • 6. Facilitate a self-cleansing effect compared to the acrylic
    • ♦ What must be considered to maintain the health in the  area between soft tissue and abutment?
    • 1. Impaction of food into the space.
    • 2. Hypertrophy of tissue into the space.
    • 3. A reduced bracing effect between the remaining teeth.
    • 4. Increased periodontal involvement.
  5. ♦ What are the infrabulge and suprabulge retainers? Name representative retainers in each of the types?
    • Infrabulge (I-bar)
    • Suprabulge (C-clasp)
  6. ♦ What are the advantages of I-bar retainers over the C-clasp retainers?
    • Minimal tooth contact
    • Minimal interference with natural tooth contour.
    • Maximum natural cleansing action.
    • Reduced display of metal for better esthetics.
    • Passive functional movement on the abutment adjacent to an extension-base
  7. ♦ What are the requirements to design the I-bar retainer?
    • To originate at a gingival area and cross the tooth-tissue junction at right angles.
    • To engage an undercut 0.01 inch or 0.25 mm. The
    • abutment needs to have the undercut around the
    • midline.
    • The tip of the I-bar should be located ideally within the cervical 1/3 or could be lower than the cervical ½.
    • The retention area should be at least 1 mm above the gingival margin
    • To extend in a straight line down (5-7mm) to create
    • sufficient flexibility; therefore, severe soft tissue undercut is a contraindication of I-bar Above the height of contour of the soft tissue
    • When no undercut found, a retentive area, or a dimple, can be created by a round bur, with an
    • approximately 1.5 mm diameter and an adequate depth depending on the contour of the abutment.
    • To be reciprocated by one of the following 3 structures:
    • (1) a combination of a proximal plate and minor connector, Passive Active
    • (2) a passive retainer, or
    • (3) a plate.
  8. Proximal Plates (a metal structure facing a guide plane): Fundamentals in guide plane preparation
    • 1. The larger, the better bracing.
    • 2. Curvilinear prep within the enamel.
    • 3. Therefore, they can not always be prepared fully to the gingiva.
    • 4. Preserve facial anatomy in the esthetic zone.
    • 5. The more parallel each other, the more retention can be generated.
    • 6. The more parallel each other, the longer bracing and retention last.
  9. Which is first to prep, rests or guide planes ?
    Guide planes.