Prosthodontics & Occlusion · patient case question
In a patient with COMPLETE dentures, what occlusal scheme should be established?
Patient case: New Dentures That Never Felt Right
Patient: 71-year-old female
Chief Complaint: “These dentures make my face look collapsed and I whistle when I talk.”
Background: Maxillary complete denture and mandibular RPD made three years ago elsewhere. Chronic dry mouth.
Medications: Amitriptyline, oxybutynin, atenolol
Vital Signs: BP 134/78 mmHg · HR 68 bpm · RR 16 · T 98.4°F
Findings: Reduced lower facial height with deep nasolabial folds and angular cheilitis. The maxillary denture drops on wide opening. The posterior border ends short of the vibrating line. Mucosa is dry and tacky; the mirror sticks to the buccal mucosa.
Show answer and explanation
Correct answer: A. Bilateral balanced occlusion — simultaneous contact on both sides in centric and in excursions
- A. CORRECT. BILATERAL BALANCED OCCLUSION is the scheme for complete dentures, and the reason is mechanical rather than biological. A complete denture is a free-floating prosthesis retained by a peripheral seal. If contact occurs on one side only during an excursion, the base tips and the seal breaks on the other side. Simultaneous contact bilaterally — and anteriorly and posteriorly — keeps both bases seated. Centric relation is used as the reference position because there is no reproducible tooth-determined position in an edentulous patient.
- B. Mutually protected occlusion with canine guidance is the scheme for the NATURAL dentition, where the periodontal ligament and the roots resist lateral load. Applied to a complete denture, canine guidance would tip the base off the ridge on every lateral movement.
- C. Posterior disclusion is the defining feature of a mutually protected scheme and is precisely what a complete denture cannot tolerate.
- D. Group function is likewise a natural-dentition scheme, appropriate where canine guidance is not achievable.
Note: ⚑ FLAG. The recall keyed 'centric relation with mutually protected occlusion only.' Centric relation IS correct as the reference position, but the excursive scheme for complete dentures is BILATERAL BALANCED, not mutually protected. Note the exception: an implant-retained or implant-supported prosthesis is stable enough to use canine guidance.
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