A resorbed ridge and a sore denture

Correct answer: A. The buccal shelf

• A. CORRECT. The BUCCAL SHELF is bounded by the external oblique ridge buccally, the crest of the residual ridge lingually, the buccal frenum anteriorly and the retromolar pad posteriorly. Two properties make it the primary stress-bearing area: it is covered by DENSE CORTICAL bone, and it lies at RIGHT ANGLES to the direction of vertical occlusal force. The slopes of the residual ridge are usually named alongside it.
• B. The retromolar pad is a SECONDARY stress-bearing area, and its more important role is as a posterior LIMITING structure — the denture must cover its anterior two-thirds to achieve the posterior seal. It is also the landmark for the occlusal plane and for setting the second molar.
• C. The mylohyoid ridge is a RELIEF area: sharp, covered by thin mucosa, and a classic source of lingual soreness. It is relieved, never loaded.
• D. The CREST of the mandibular residual ridge is cancellous, it is the site of ongoing resorption, and it tolerates load poorly — it is relieved rather than loaded. This is the option most candidates take.

Note: ⚠️ The recall author chose ‘alveolar ridge’ and doubted it. The examinable answer for the mandible is the BUCCAL SHELF. Keep the maxillary counterpart separate: there the primary stress-bearing areas are the HORIZONTAL HARD PALATE and the posterior ridge slopes, with relief over the incisive papilla, the midpalatine raphe or torus, and the crest of a flabby anterior ridge.

Correct answer: C. Maxilla upward and inward (centripetal); mandible downward and outward (centrifugal)

• A. The maxilla does not widen. Its ridge migrates palatally, which is why an old maxillary denture becomes progressively too large for the ridge it sits on.
• B. If both were centripetal the interarch relationship would stay proportionate, and the characteristic pseudo-prognathism would never develop.
• C. CORRECT. In the MAXILLA the labial and buccal plates are thinner, so resorption proceeds upward and INWARD and the arch becomes progressively SMALLER — CENTRIPETAL. In the MANDIBLE the lingual plate is thinner at the crest, so resorption proceeds downward and OUTWARD and the arch becomes progressively WIDER — CENTRIFUGAL. The two moving in opposite directions is why a long-term edentulous patient develops an apparent Class III, pseudo-prognathic relationship, and why the posterior teeth in such a case are often deliberately set in crossbite.
• D. This reverses both jaws and would predict a worsening Class II, which is not what is observed clinically.

Note: The mandibular ridge resorbs roughly FOUR TIMES faster than the maxillary — Atwood's classic observation — which is why the lower denture is almost always the problem. Practical consequences: set maxillary posterior teeth slightly buccal and mandibular slightly lingual to the crest as resorption advances, reline on a defined schedule, and consider two implants in the mandibular canine regions for an overdenture, which is now widely regarded as the minimum standard of care for the edentulous mandible.

Correct answer: D. Heat-cured (heat-polymerised) acrylic resin

• A. Soft liners are the WORST of the group. They are inherently porous, they degrade and lose their plasticiser over time, they cannot be polished, and they colonise heavily — which is why they need frequent replacement and are a poor long-term solution.
• B. Light-cured repair materials are convenient chairside but are more porous than a properly processed heat-cured base.
• C. Chemically cured resin is the classic answer to the opposite question. It polymerises without controlled heat and pressure and retains a HIGHER content of residual monomer, and that excess monomer leaves the material more POROUS with a rougher surface — which is exactly what allows Candida albicans to adhere and to survive mechanical cleaning. This is why chairside relines and repairs are more prone to candidal infection, and it is relevant to this patient, whose lower denture was relined chairside.
• D. CORRECT. HEAT-CURED PMMA is polymerised under controlled heat and pressure, leaving the LOWEST residual monomer content of the acrylics. Less residual monomer means a denser, harder, less porous material that takes and holds a high polish — and since surface porosity and roughness are what permit candidal adhesion, heat-cured resin is the least colonised of the options.

Note: Whatever the material, management of denture stomatitis is a package rather than a prescription: leave the denture OUT at night, disinfect the prosthesis itself because it is the reservoir (chlorhexidine soak, or dilute hypochlorite for all-acrylic dentures only — never one with metal components), treat the mucosa with a topical antifungal, and correct the fit. Treating the mouth alone guarantees reinfection.