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Restorative & Materials · patient case with 5 questions

Erosion in a High-Acid Diet

demo: 27-year-old female

chief: “My back teeth feel notched and everything is sensitive.”

history: Consumes 5–7 whole lemons daily. Reports nocturnal bruxism. No reflux, no purging behavior.

meds: None

findings: Cupped, smooth, glossy defects on the occlusal surfaces of the posterior teeth with amalgam restorations standing proud of the surrounding enamel. Generalized dentin hypersensitivity.

Question 1

Where is the erosive damage in this patient most evident, and what is the dentist's primary obligation?

  1. Cervically — restoration with composite is the first step
  2. Incisally — the priority is an occlusal guard
  3. Interproximally — the priority is fluoride varnish
  4. Occlusally — the dentist must address the causative behavior, not only restore the defects
Show answer and explanation

Correct answer: D. Occlusally — the dentist must address the causative behavior, not only restore the defects

  • A. Cervical erosion is more typical of abrasive brushing combined with acid; this presentation is occlusal.
  • B. Incisal wear alone does not match the described posterior cupping.
  • C. Interproximal surfaces are relatively protected from direct acid contact and are not the presenting site here.
  • D. Correct. The combination of dietary acid and bruxism concentrates the loss occlusally, producing cupping with restorations standing proud. Restoring without changing the behavior guarantees recurrence.

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Question 2

Which advice is most appropriate for this patient regarding her lemon consumption?

  1. Reduce the frequency of lemon intake, and rinse with water — not brush — immediately after acid exposure
  2. Brush vigorously with a whitening toothpaste immediately after each lemon
  3. Continue the lemons but add a nightly hydrogen peroxide rinse
  4. Replace whole lemons with sipped lemonade throughout the day
Show answer and explanation

Correct answer: A. Reduce the frequency of lemon intake, and rinse with water — not brush — immediately after acid exposure

  • A. Correct. Reducing frequency limits total acid exposure, and rinsing with water or a bicarbonate solution neutralizes the surface. Brushing should be delayed roughly 30–60 minutes while the softened enamel remineralizes.
  • B. Brushing softened enamel immediately after an acid challenge accelerates loss; abrasive whitening pastes make it worse.
  • C. Peroxide does nothing for erosion and adds another irritant.
  • D. Sipping lemonade over hours extends the acid exposure time and is worse than a single concentrated challenge.

Note: Frequency of exposure, not concentration, is the dominant erosive variable — sipping is the poorer choice.

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Question 3

An elderly patient presents with multiple Class V cervical lesions, poor manual dexterity, and moderate xerostomia. Which restorative material is most appropriate?

  1. Gold foil
  2. Glass ionomer or resin-modified glass ionomer
  3. Dental amalgam
  4. Feldspathic porcelain veneers
Show answer and explanation

Correct answer: B. Glass ionomer or resin-modified glass ionomer

  • A. Gold foil is technique-sensitive, time-consuming, and essentially obsolete for this indication.
  • B. Correct. Glass ionomer bonds chemically to dentin, releases fluoride, tolerates a moist field, and performs well in a high-caries-risk, xerostomic patient with limited hygiene.
  • C. Amalgam requires mechanical retention and undermines cervical tooth structure in a Class V preparation.
  • D. Porcelain veneers are an esthetic elective option, poorly suited to cervical caries control in this patient.

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Question 4

For a Class IV composite restoration on a maxillary central incisor, where should the bevel be placed?

  1. On cementum, apical to the CEJ
  2. On enamel, around the cavosurface margin
  3. On dentin, at the axial wall
  4. No bevel should be placed on a Class IV preparation
Show answer and explanation

Correct answer: B. On enamel, around the cavosurface margin

  • A. Placing margins on cementum compromises the bond and invites recurrent caries.
  • B. Correct. Beveling enamel exposes the ends of the enamel rods, which improves etch pattern and bond strength, and it blends the restoration margin optically for a better esthetic transition.
  • C. Bevels on dentin do not improve bonding and weaken the remaining structure.
  • D. The Class IV bevel is one of the standard indications for beveling in composite dentistry.

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Question 5

The configuration factor (C-factor) of a cavity preparation refers to:

  1. The ratio of filler to resin matrix in the composite
  2. The ratio of bonded to unbonded surfaces — a higher ratio produces greater polymerization shrinkage stress
  3. The ratio of enamel to dentin at the cavosurface margin
  4. The ratio of depth to width of the preparation
Show answer and explanation

Correct answer: B. The ratio of bonded to unbonded surfaces — a higher ratio produces greater polymerization shrinkage stress

  • A. Filler loading affects shrinkage magnitude but is a material property, not the C-factor.
  • B. Correct. C-factor is bonded surfaces divided by unbonded (free) surfaces. Fewer free surfaces means less opportunity for the composite to flow during curing, so shrinkage stress concentrates at the bond — which is why a Class I preparation has the highest C-factor and a Class IV the lowest.
  • C. The enamel-to-dentin ratio affects bond quality but is a different concept.
  • D. Depth-to-width ratio describes preparation geometry generally, not the configuration factor.

Note: The source wording for this item was garbled. The definition above is the accepted one; incremental layering and flowable liners are the standard means of reducing C-factor stress.

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