Based on the lecture materials provided in your notebook, here is a comprehensive overview of complete denture relines, rebases, the specific materials used, and their clinical indications.
1. Denture Reline vs. Denture Rebase
- Denture Reline: A procedure to resurface the intaglio (fitting) surface of a denture with new base material, improving its fit without altering the rest of the denture.
- Denture Rebase: A procedure that replaces most of the denture base material while retaining the original teeth in their correct relationship. It is less likely to undergo dimensional change during processing and results in a stronger, more durable prosthesis.
General Indications for Relining/Rebasing
- To compensate for continuous alveolar resorption of supporting structures, which directly compromises denture stability, retention, and facial height (OVD).
- Can be localized (to correct specific defects like the posterior palatal seal or a peripheral border) or global (covering the entire intaglio surface of a loose denture).
2. Comprehensive Classification of Materials
Denture relines are split into chairside (direct) and laboratory (indirect) procedures, further subclassified into hard and soft materials.
| Reline/Rebase Type | Common Materials | Service Life | Primary Indications & Characteristics |
|---|---|---|---|
| Chairside Soft | Self-curing plasticised acrylic resins |
(e.g., Ufi Gel Soft, GC ReLine Soft, CoSoft) | ~6 weeks | * Immediate post-surgery healing
* Tissue conditioning prior to final impressions
* Difficult to achieve even thickness |
| Chairside Hard | Self-curing acrylic resins
(e.g., Ufi Gel Hard, GC Reline Material, Co-rect) | ~6 months | * Immediate/short-term fit improvement
* No cushioning effect
* Exothermic setting reaction |
| Laboratory Soft | Heat-cured silicones
(e.g., Molloplast B) | ~3 years | * Severely resorbed/atrophic mandibular ridges
* Chronically uncomfortable or painful chewing
* High durability and uniform thickness |
| Laboratory Hard Reline | Heat-cured polymethyl methacrylate (PMMA) | Long-term | * Long-term correction of bone resorption
* Requires a second heat-curing cycle (risk of original base distortion) |
| Laboratory Hard Rebase | Heat-cured polymethyl methacrylate (PMMA) | Maximum longevity | * Severe global bone resorption
* Replaces nearly all old acrylic to eliminate processing distortion risks |
3. In-Depth Material Breakdown & Clinical Protocols
A. Chairside Soft Liners
- Indications: Used immediately following oral surgery or as a short-term therapeutic measure to improve stability and promote tissue healing under an ill-fitting denture before making a final impression.
- Clinical Protocol (e.g., Ufi Gel Soft):
- Clean and dry the intaglio surface of the denture.
- Apply the specific adhesive and let it become tacky.
- Extrude the soft liner directly from the mixing cartridge nozzle onto the denture base.
- Seat the denture in the mouth. Instruct the patient to apply light biting force to maintain correct occlusion until the material fully sets.
- Remove the denture and trim away the excess material.
B. Chairside Hard Materials
- Indications: Indicated when a hard reline is required immediately, providing a longer service life than soft chairside options without requiring laboratory processing time.
- Clinical Protocol & Curing Considerations:
- Base Reduction: Use an acrylic bur to grind away a thin layer of the intaglio surface, creating a fresh surface for bonding.
- Protection: Apply Teflon tape to the polished surfaces to facilitate easier cleanup.
- Application: Mix the powder/liquid to a creamy consistency and apply evenly to the intaglio surface.
- Seating & Muscle-Molding: Seat the denture; have the patient close into light, even occlusal contact. Gently muscle-mold the peripheral borders while keeping the denture strictly in occlusion.
- Exothermic Management: Because the polymerization reaction is exothermic, remove the denture from the mouth as soon as the material reaches a rubbery consistency. Allow it to finish setting on the bench to protect the tissues from heat.
- Finishing: Trim gross excess with curved scissors while rubbery, and use an acrylic bur and rubber points to smooth and polish once fully set.
C. Laboratory Soft Liners (e.g., Molloplast B)
- Indications: Primarily indicated for mandibular dentures where severe ridge resorption has minimized the denture-bearing area, making standard chewing highly uncomfortable.
- Characteristics & Clinical Limitations:
- Processed to a uniform, durable thickness of about 2–3 mm using a sophisticated two-stage laboratory curing technique.
- Adhesion Problems: Can suffer from separation from the hard acrylic base if precise technique is not followed.
- Staining & Maintenance: Prone to staining over time, though it tolerates sodium hypochlorite cleansers better than hard liners. Trimming is clinically difficult; adjustments run the risk of exposing the underlying hard base in crucial areas.
D. Laboratory Hard Reline & Rebase (PMMA)
- Indications: Indicated for long-term correction of alveolar changes and loose dentures. Rebasing is chosen over relining when the bulk of the old denture base acrylic needs replacement to minimize the risk of dimensional changes or warpage during a second laboratory heat-curing cycle.
- Clinical Assessment Tip: The fit of the denture prior to a laboratory reline/rebase can be accurately assessed using a fast-setting PVS material like Fit Checker; an unevenly thick or thin layer confirms a poor fit and the need for treatment.
- Clinical Protection Protocol: To prevent laboratory processing materials from adhering to the teeth and to ease post-laboratory cleanup, clinicians apply a layer of Vaseline and Teflon tape to the buccal and labial surfaces of the denture teeth before taking the reline impression.
- The Rebase Laboratory Step: During a rebase flasking process, a layer of laboratory putty is adapted to the labial and buccal surfaces of the teeth (leaving the occlusal/incisal surfaces exposed). This step is critical to preserve the original Occlusal Vertical Dimension (OVD) and prevent tooth displacement when packing the new PMMA dough.
Are you preparing for a clinical technique class or looking for details on a specific reline/rebase lab prescription?