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Prosthodontics & Occlusion · patient case with 5 questions

Removable Partial Denture Design

demo: 64-year-old male

chief: “I want to replace my back teeth on both sides.”

history: Has not attended a dentist in several years. Reports dry mouth.

meds: Amitriptyline, hydrochlorothiazide

findings: Mandibular arch missing #17–19 and #30–32 bilaterally, with all anterior teeth present. Generalized marginal inflammation and heavy calculus. Xerostomia. No frank cavitated lesions found today.

Question 1

This mandibular arch is classified as:

  1. Kennedy Class II
  2. Kennedy Class III
  3. Kennedy Class IV
  4. Kennedy Class I
Show answer and explanation

Correct answer: D. Kennedy Class I

  • A. Class II is a unilateral edentulous area posterior to the remaining teeth.
  • B. Class III is a unilateral edentulous area with natural teeth both anterior and posterior to it.
  • C. Class IV is a single edentulous area crossing the midline, anterior to the remaining teeth.
  • D. Correct. Bilateral edentulous areas posterior to the remaining natural teeth define Kennedy Class I — a bilateral distal extension case.

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Question 2

What is the primary function of the lingual bar major connector in this design?

  1. To provide rigidity, so that forces are distributed among the supporting structures
  2. To provide the principal vertical support for the prosthesis
  3. To provide indirect retention at the distal extension
  4. To provide direct retention against dislodging forces
Show answer and explanation

Correct answer: A. To provide rigidity, so that forces are distributed among the supporting structures

  • A. Correct. Rigidity is the defining requirement of any major connector. Without it, forces concentrate on individual abutments instead of being distributed across the arch.
  • B. Vertical support comes principally from rests on the abutment teeth and, in a distal extension, from the residual ridge.
  • C. Indirect retention comes from rests placed on the opposite side of the fulcrum line, not from the connector itself.
  • D. Direct retention is supplied by the clasp assemblies, not the major connector.

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Question 3

Applying the ADA caries risk assessment to this patient — no cavitated lesions today, but heavy calculus, gingival inflammation, xerostomia, and years without care — he is classified as:

  1. High caries risk
  2. Moderate caries risk
  3. Low caries risk
  4. Risk cannot be assigned without radiographs
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Correct answer: A. High caries risk

  • A. Correct. Caries risk assessment is prospective. Xerostomia, heavy plaque and calculus, and irregular dental attendance are strong risk indicators that place him in the high-risk category regardless of today's cavity count.
  • B. Moderate risk would apply with fewer or milder risk factors; xerostomia alone is a powerful driver toward high risk.
  • C. Low risk requires good hygiene, adequate salivary flow, regular care, and no recent caries experience.
  • D. Risk assessment is a clinical judgment made from history and examination; radiographs refine but do not gate it.

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Question 4

The patient later receives an implant-retained mandibular overdenture. What is the accepted minimum number of implants, and where are they optimally placed?

  1. Two implants, positioned in the canine regions
  2. Four implants, positioned in the canine and first molar regions
  3. One midline implant
  4. Six implants distributed across the arch
Show answer and explanation

Correct answer: A. Two implants, positioned in the canine regions

  • A. Correct. Two implants in the canine regions is the accepted minimum for a mandibular overdenture — the canine sites offer good bone volume, sit anterior to the mental foramen, and give favorable attachment spacing.
  • B. Four implants is the accepted minimum for a maxillary overdenture, where bone quality is poorer.
  • C. A single implant is not a recognized standard of care for an overdenture.
  • D. Six implants exceeds what is needed for a mandibular overdenture, though it may be used for a fixed prosthesis.

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Question 5

For a maxillary implant-retained overdenture, what is the accepted minimum number of implants?

  1. Two
  2. Six
  3. Three
  4. Four
Show answer and explanation

Correct answer: D. Four

  • A. Two implants is the mandibular minimum; in the maxilla it is generally considered insufficient.
  • B. Six implants is common for a fixed maxillary prosthesis but exceeds the overdenture minimum.
  • C. Three is not a recognized standard for a maxillary overdenture.
  • D. Correct. Maxillary bone is less dense and the arch must resist greater lateral loading, so four implants is the accepted minimum.

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