Preclinics of Dental Prosthetics · MU Sofia

71. Technology of complete dentures. Baseplates and occlusal rims. Recording of interocclusal relationship. Mounting master casts on an articulator.

Covers the record bases and occlusal rims used to transfer jaw relationships to the laboratory, including base thickness and materials in a table. It then explains the rims' dimensions and placement in the mouth, shown in a second table and a labelled picture, and walks through recording vertical dimension, centric relation and marking the rims. The note finishes with mounting the upper and lower casts on an articulator and the factors that affect accuracy.

Inside: 5 sections · 1 labelled picture · 2 tables · 15 flashcards · 3 min

Topic 71 of 75 in the MU Sofia syllabus for Preclinics of Dental Prosthetics (Dental Medicine, Year 2). The free AceMed note covers it in 5 sections, about 353 words (3 min of reading), with 15 flashcards.

In this note

  1. Introduction
  2. Record (base) plates
  3. Occlusal rims
  4. Recording the interocclusal relationship
  5. Mounting on the articulator

Introduction

Once the master casts exist, the dentist must transfer to the laboratory how the edentulous jaws relate to each other: how high (vertical dimension), where (centric relation) and which plane the teeth will follow. This is done with record bases and occlusal rims.

Record (base) plates

A temporary base adapted to the master cast that carries the occlusal rim.

  • Well adapted, rigid, dimensionally stable and retentive.
  • About 1 mm thick over the crest and facial slope (room for teeth), 2 mm on the palatal and lingual flanges.
  • Smooth, rounded borders; the lower plate reinforced with wire on the lingual side.

Occlusal rims

Together the two rims are about 40 mm high: the typical height of the edentulous jaws.

Recording the interocclusal relationship

  1. Upper rim first: adjust for lip support; trim so it shows about 2 mm below the relaxed upper lip; make it parallel to the interpupillary line (front) and Camper's line (side), checked with a Fox plane.
  2. Vertical dimension: find the rest vertical dimension (phonetics, swallowing, relaxed lips), subtract a freeway space of 2–4 mm (seen at the premolars), and trim the lower rim to that occlusal vertical dimension.
  3. Centric relation: guide the mandible back to its unstrained hinge position (the patient may swallow or touch the tongue to the back of the palate). V-shaped notches 1–2 mm deep in the premolar–molar area of one rim, and soft wax or bite paste on the other, lock the rims together; or a gothic arch tracer is used.
  4. Mark the rims: midline, canine lines (corners of the mouth), high and low smile lines. They guide tooth size and position.
  5. Fix the rims together with Π-shaped clamps or a heated knife in the premolar region, and remove from the mouth in one piece.

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