Denture Bases and Occlusion Blocks

Record Base and Occlusion Blocks

• Occlusion blocks are composed of occlusion rims attached to well-fitting trial denture bases.
• The record base and occlusion rims are essential for establishing facial contours.
• They assist in tooth selection and maintaining the vertical dimension of occlusion during record-making.
• Interocclusal records are created using these components.
• The denture teeth' arrangement is also facilitated by record base and occlusion rims
• The external surface of the complete denture's waxed-up mold is also produced using these elements.

Requirements of a Trial Denture Base

• A trial denture base should be rigid.
• It needs to fit the cast accurately and have proper extensions.
• It should maintain dimensional stability with minimal warpage during use.
• Undercuts must be relieved to avoid damaging the cast during placement and removal.
• The base should be smooth and clean to ensure patient comfort.
• A uniform thickness of 2mm is desirable.
• The base needs to be easy to construct.

Wax Block Out

• Wax block out protects the master casts from tissue undercuts and irregularities.
• Base plate wax is used to block out undercuts and/or irregularities.
• The labial surface of the anterior ridge, Rugae areas and sometimes the tuberosity areas laterally are areas of concern.
• On the mandibular cast, the retromylohyoid areas may need a wax block out.

Soaking the Master Cast

• The master cast is soaked in room-temperature water for 5 minutes.
• This step expels air from within the stone; minimizing bubble-like defects in the completed record base.

Tinfoil Substitute

• A tinfoil substitute is employed as a separating medium to protect the cast and enable the record base's separation.
• The tinfoil substitute is applied twice, allowing the first layer to dry before applying the second.
• Each layer is applied as a thin film covering all surfaces of the cast, including land areas and any parts that could come into contact with the resin.

Record Base Fabrication

• The record base is created using autopolymerizing acrylic resin.
• The tinfoil substitute method is used to create the record base by applying it in two thin layers.

Record Base Dimensions

• The record base should be thinner on the crest of the ridges and buccal to the crest of ridges.
• The base should not block off spaces that denture teeth might need later on.

Occlusion Rim Fabrication and Uses

• Occlusion rims are typically created using pink modeling wax.
• Occlusion rims are vital for jaw relationship registration.
• The rims aid in selecting the proper artificial teeth as they can assist with determining the midline, high and low lip lines, canine lines, and canine line to posterior teeth distance.
• They aid in tooth arrangement preparation
• Occlusion rims provide support for lips and cheeks

Occlusion Rim Dimensions

• Posterior rims are roughly 8-10mm in width.

• Anterior rims are roughly 6-8mm in width.

• A 22mm vertical height is usually needed for the mandibular occlusion rim.

• The posterior area's height corresponds to two-thirds the height of the retromolar pad.

• The labial surface of the maxillary occlusion rim in the central area is roughly 6-8 mm anterior to the middle of incisive papilla and is labially inclined.

• The record rim and base should not be a part of the finalized dentures.

• Inform patients that they will feel slightly loose due to the blocked-out undercuts.

Posterior Palatal Seal (PPS)

• The posterior palatal seal area must be prepared.
• The varying degrees of compressibility of the tissues (up to 1mm) are marked out accordingly.
• The vibrating line establishes the posterior boundary of the PPS
• This is defined with a #6 round bur in a depth of 0.5–1mm.
• Other regions require smoothening by using Cleoid-Discoid instruments.
• The anterior border of the PPS requires feathering.

This quiz covers the essential components of occlusion blocks and trial denture bases used in dental prosthetics. Learn about their functions, requirements, and how they assist in the dental record-making process. Test your knowledge on the critical aspects of denture design and patient comfort.