Layered Prostheses Evaluation

• Layered prostheses (metal-ceramic & layered all-ceramic) require two evaluations: metal evaluation and reevaluation after veneer application.
• During metal evaluation, dentists check marginal integrity, stability, occlusion, and substructure design.
• A second evaluation at the bisque stage involves checking marginal integrity, stability, distortion from porcelain firing, proximal contacts, contours, shade match, texture, and glaze.
• FDPs require careful assessment of tissue contact of pontics, connector location, and shape to ensure passive adaptation and prevent tissue irritation.

Evaluation Sequence

• Seating should be assessed.
• Marginal integrity should be assessed.
• Retention and stability should be assessed.
• Occlusion should be assessed.
• Proximal contact should be assessed.
• Contour, alignment, and occlusal anatomy should be assessed.
• Pontic should be assessed.
• Connector should be assessed.
• Esthetics and characterization should be assessed.
• Radiographic evaluation should be assessed.

Seating

• Restorations should seat with minimal friction, with any resistance indicating a need to determine the cause.

Excessive Proximal Contact

• Proximal contacts are assessed first because excessive contact can prevent seating and lead to marginal discrepancies.

All-Metal Restorations

• Tight proximal contacts are located by observing shiny marks on a matte finish.

Ceramic Restorations

• Areas of tight contact are identified using thin marking tape on unglazed ceramic and adjusted with a cylindrical stone.
• After glazing, contact changes may occur due to pyroplastic surface flow during firing and adjustments should be repolished.

Presence of Nodules on the Fitting Surface

• Magnifying lens use is important to examine the fitting surface, especially the inner angles for nodules.
• Small non-critical nodules should be removed.
• Large or critical area nodules require a remake

Over Extension of Gingival Margin

• An error in die making or wax pattern carving is the cause and requires a remake.

Tight Casting

• Tight casting is due to inaccuracy in fabrication steps.
• A quick-drying liquid or pressure-indicating paste is applied to the fitting surface, and seating scratches will reveal tight areas.
• Small, well-defined tight areas are reduced by spot grinding, while multiple or generalized areas require electrostripping.

Materials for Detecting Binding

• Materials used to detect where a casting binds against an occlusal or axial wall include:
  • Disclosing waxes
  • Airborne-particle abrasion
  • Water-soluble marking agents
  • Special elastomeric detection pastes

Lack of Parallelism of Abutments

• Improper preparation and faulty temporary restorations can cause lack of parallelism.

Faulty Assembling & Soldering

• Faulty assembling and soldering can be a cause of binding.

Margin Integrity

• Completed restorations should adapt to the margins without internal binding against the tooth preparation.
• Cement film thickness should be minimal to prevent dissolution of the luting agent.

Margin Assessment

• A sharp explorer is used to check margin adaptation from restoration to tooth and vice versa.
• Resistance from restoration to tooth indicates a short horizontal margin that requires a remake.
• Resistance from tooth to restoration indicates horizontal over-extension and a small overhang can be adjusted if accessible.
• Resistance in both directions suggests a gap or open margin, requiring a new impression.
• Subgingival margins must be finished on the die since they are not accessible in the mouth and precementation radiographs can be used for assessment.

Stability

• Restorations should initially be retained by tenso-frictional grip.
• Assess stability on the prepared tooth by ensuring no rocking or rotation under force, instability can cause failure.
• Correct instability from small nodules. New castings are necessary if there is distortion.

Occlusion

• Articulating papers are used to identify undesirable eccentric and centric contacts.
• Only supraoccluded restorations are adjusted.
• Restoration out of occlusion requires a remake of the metal or monolithic ceramic.
• Metal-ceramic or all-ceramic restorations with high-strength cores need porcelain addition and refiring.
• Gross occlusal adjustments are better done in bisque stage, minor adjustments can be polished after glazing.

Metal Restorations

• For metal restorations, the occlusal surface is abrasioned with aluminum oxide to create a matte finish and adjustments are made where shiny marks appear.

Proximal Contact

• Proximal contacts prevent seating and cause marginal discrepancies.
• Ideal contacts support abutment and tooth position and are easy to maintain.
• Contacts should be located properly, have the right size and tightness, and should allow unwaxed floss to snap through easily.

Deficient Contact

• A metal casting with a deficient proximal contact can be corrected by soldering.

Ceramic Restorations

• Additional firing is required to fix a deficient ceramic contact including adding porcelain at the bisque stage or using lower fusing "addon" porcelain after completion.
• Major corrections involves adding additional porcelain, with limits to firing times to avoid devitrification.

Contour, Alignment, Occlusal Anatomy

• Contour and alignment should match neighboring and contralateral teeth. Occlusal anatomy should replicate the contralateral teeth.
• Ceramic restorations should be moistened during bisque stage to reflect light like a glazed restoration.

Emergence Profile

• The emergence profile is the tooth surface gingival to the height of contour and should be flat or concave.
• Convexity or ledges make plaque removal difficult and cause inflammation.
• Excessive bulk is a common fault associated with periodontal disease.
• Do not grind porcelain and metal simultaneously on metal-ceramic restorations to prevent metal particle transfer.

Occlusal Anatomy

• Adjust occlusal interferences on posterior teeth. Porcelain contacts may need minor readjustment due to pyroplastic flow.

Incisal Edge

• On anterior teeth, using a well-adjusted interim restoration cast or a photograph of satisfactory interim restorations to establish proper position and shape of the incisal edge.
• During "F" sound pronunciation, the incisal edge of the maxillary central incisors touches the lower lip's wet-dry line.
• Refine incisal edge shape in the mouth and small adjustments avoid removing translucent incisal porcelain.
• 1-2 mm of clinical crown is visible on maxillary central and lateral incisors when the upper lip is relaxed.
• Lateral incisors should be 0.5-2 mm shorter than central incisors.

Negative Space

• Embrasures enhance separation between restorations.
• Absence of incisal embrasures creates an artificial apperance.
• Interproximal embrasures should be narrow and deep. Absence of interproximal embrasures creates an artificial appearance.

Line Angles

• The line angles define the shape of the tooth.

Overall Contour

• Contour should match adjacent teeth. Moistening and observing reflections may reveal needed corrections.

Pontic

• Pontic-ridge relationship must be self-cleansing.
• Pressure of the pontic against the ridge causes blanching.
• Dental floss should pass between the pontic and ridge anteroposteriorly.
• The pontic should have the correct contour for food sweep, massaging the mucosa rather than impinging.

Connector

• Rigid connectors need adequate strength and design.
• Non-rigid connectors need adequate retentive qualities and design.

Esthetics

• Fixed prostheses should harmonize with natural teeth in form, size, texture, characterization, and shade match.

Radiographic Checking

• Radiographs verify gingival and margin adaptation, especially interproximally.