13.3 Post-Insertion Problems, Sore Spots, Relining & Rebase Procedures

13.3 Post-Insertion Problems, Sore Spots, Relining & Rebase Procedures

The delivery and post-insertion maintenance of removable dentures represent a critical phase in prosthodontic therapy. Patient satisfaction, functional adaptability, and mucosal health depend on systematic clinical troubleshooting. For the ADC Written Examination, candidates must master the diagnostic differentiation of post-insertion complaints, phonetic evaluation, and the clinical protocols for hard relines, rebases, and temporary soft tissue conditioning.

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1. Denture Insertion Protocol & Clinical Remounting

Initial insertion of complete or partial dentures requires systematic evaluation before final delivery to the patient.

Intaglio Surface & Border Inspection

• Intaglio Adjustment: Apply Pressure Indicator Paste (PIP) in thin, uniform streaks across the fitting surface. Seat the denture with vertical pressure. Displace high spots (areas where paste is completely wiped away exposing acrylic) using an acrylic bur. Common impingement zones include the incisive papilla, mylohyoid ridge, canine eminences, and maxillary tuberosities.
• Border Extension Check: Apply disclosing wax to flanges to confirm border length and thickness without muscular impingement.

Clinical Remount Procedure

Intraoral occlusal evaluation is inherently imprecise due to mucosal resiliency, which allows dentures to tilt or shift under biting pressure. A Clinical Remount eliminates processing errors and corrects occlusion on a rigid articulator:

1. Take a new facebow record of the maxillary denture (or remount cast).
2. Take an intraoral Centric Relation interocclusal bite registration (using zinc oxide eugenol or rigid wax) at a slightly opened VDO before tooth contact.
3. Mount casts on a semi-adjustable articulator and perform selective grinding.
4. Selective Grinding Rules: Adjust non-supporting cusps (BULL rule: Buccal Upper, Lingual Lower) for working side interferences. Do not reduce supporting cusps (lingual upper, buccal lower) unless hyper-occlusion exists in Centric Relation.

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2. Systematic Diagnosis of Post-Insertion Sore Spots

Distinguishing the underlying etiology of mucosal sore spots is vital for targeted corrective therapy.

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3. Speech & Retention Troubleshooting

Phonetic tests evaluate denture contour and anterior tooth position.

Phonetic Diagnostics

• 'S' Sounds (Phonetics & Closest Speaking Space):
  • Whistling on 'S': Occurs when the palatal vault acrylic behind the upper central incisors is too narrow or deep, allowing air escape. Corrected by adding acrylic palatally behind upper anterior teeth.
  • Lisping ('Th' replacing 'S'): Occurs when palatal acrylic behind upper incisors is too thick or anterior teeth are positioned too far palatally.
• 'F' and 'V' Sounds (Fricatives): Maxillary incisal edges should lightly contact the wet-dry junction of the lower lip during speech (e.g., saying "Fifty-Five").
• 'B', 'P', and 'M' Sounds (Labials): Require complete lip closure. Inability to form labial seals indicates excessive VDO.

Retention & Stability Troubleshooting

• Dislodgement During Opening / Yawning: Caused by an overextended buccal flange or excessive thickness of the distobuccal flange of the maxillary denture, which impinges on the anterior border of the coronoid process of the mandible during mouth opening.
• Dislodgement During Speaking / Swallowing: Caused by an overextended lingual flange or posterior palatal seal extending beyond the vibrating line onto the movable soft palate or impinging on the palatoglossus muscle.

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4. Relining, Rebasing & Repair Protocols

Progressive residual ridge resorption degrades denture retention and VDO over time. Restoration of fit requires relining or rebasing.

Definitions & Indications

• Relining: The process of adding a new layer of acrylic resin material to the intaglio (fitting) surface of a denture to adapt it to resorbed mucosal ridges. Indicated when retention/stability is lost, but VDO, aesthetics, and tooth condition remain satisfactory.
• Rebasing: The process of replacing the entire acrylic denture base material, retaining only the original prosthetic teeth and spatial arrangement. Indicated when the denture base is cracked, porous, discolored, or severely ill-fitting, but teeth are unworn.

Hard Reline Impression Techniques

• Closed-Mouth Technique (Preferred): Functional impression material (PVS light body or ZOE) is applied into the prepared intaglio surface. The patient closes into Centric Relation at the established VDO while the material sets. This ensures occlusal harmony during setting.
• Open-Mouth Technique: Operator manually seats the denture while holding the base in position, independently registering the mucosal seat without occlusal contact.

Temporary Soft Tissue Conditioners

Tissue conditioners (e.g., Poly(ethyl methacrylate) [PEMA] with plasticizer) are viscoelastic materials applied to traumatized, inflamed, or distorted basal seat mucosa. Functions include:

1. Recondition distorted mucosal tissues before taking master impressions for relining or new dentures.
2. Temporary reline for immediate dentures during post-extraction wound healing.
3. Functional impression material (flows dynamically over 24–48 hours).

• Maintenance Alert: Tissue conditioners must be replaced every 3 to 14 days because plasticizers leach into oral fluids, causing the material to harden, roughen, and harbor Candida micro-organisms.