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Porcelain Inlay and Onlay

Porcelain Inlay and Onlay. Preparation and Restoration. Dr. Ignatius Lee. 1970’s Posteriors: amalgam Anteriors: composite. 2000’s Posteriors: amalgam (material specific), composite (lesion specific) Anteriors: composite. Restorative Options - Direct.

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Porcelain Inlay and Onlay

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  1. Porcelain Inlay and Onlay Preparation and Restoration Dr. Ignatius Lee

  2. 1970’s Posteriors: amalgam Anteriors: composite 2000’s Posteriors: amalgam (material specific), composite (lesion specific) Anteriors: composite Restorative Options - Direct

  3. Evolution of Cavity Preparation Design for Posterior Composite • Taking into consideration the differences in the physical properties between the two materials (amalgam vs composite); and based on the rationale of the cavity preparation design for amalgam • Questions were asked: Do we need convergent walls? retention grooves? Worry about unsupported enamel? Extension for prevention? Do we need bulk? • New cavity preparation design for posterior composite was created; it was based on specific characteristic of the material.

  4. Why are we talking about amalgam/composite • Example of utilizing the skill/knowledge we acquired in using a specific material/procedure (amalgam restoration) and applying it on a new material/procedure (composite restoration) • Preparation skills should be easily transferable. • Knowledge on the rationale of cavity preparation will allow us to adapt to the new material based on the material’s specific characteristic. • Answer to your question on “why are we still teaching cast gold inlay/onlay”? - when only a few dentists are doing these kinds of procedures in their offices.

  5. 1970’s Cast gold inlay/onlay, 3/4 crown, full cast crown, PFM 2000’s Cast gold inlay/onlay, 3/4 crown, full cast crown, PFM Porcelain/composite inlay/onlay Restorative Options - Indirect

  6. Differences between gold and porcelain restorations • Physical properties - porcelain more brittle • Mode of retention - bonding vs mechanical retention • Concept of margin Based on these differences, can we design a cavity preparation for using porcelain intra-coronally?? • Starting with cavity preparation design for cast gold inlay/onlay, what features do we have to modify for porcelain????

  7. Physical Properties • What cavity preparation features do we need to modify? • Bulk - more occlusal clearance • Reinforcement - bonding • Bevels contraindicated

  8. Mode of Retention • Cast gold preparation rely on 6 to 7 degree of divergent walls and sharp internal line angles. • Porcelain rely on the bonding process, no need for 6 to 7 degree divergent wall and sharp internal line anlges.

  9. Cast gold - rely on close adaptation (20u); lack of adhesion between tooth structure/cement/gold interface Porcelain - rely on the adhesion between tooth structure/resin cement/procelain to create a gap free continuous margin. No gingival bevels needed to minimize the gap. Marginal Adaptation

  10. Empress Procelain System • All procelain restoration used for inlay, onlay, full crown • Castable • Adequate marginal fit • Better wear characteristic than conventional procelain • Similar to cast gold inlay/onlay in terms of cavity preparation design

  11. Porcelain Fused to Metal Crown vs Empress: Similarities • Highly esthetic • Wear • Brittle - reinforced through the bonding process

  12. Composite vs Empress: Similarities • Mode of retention - dentinal bonding agent • Apply skills you learn for composite on the bonding process.

  13. Mechanism of Adhesion • Porcelain etched with hydrofluoric acid (micromechanical) • Bond between etched tooth and DBA - identical to composite/tooth • Silane coupling agent - chemical bond

  14. Summary of Characteristics • Highly esthetic • Acceptable marginal fit • Conservation of tooth structure • Less occlusal wear • Highly technique sensitive

  15. Indications • High esthetic demand • Replace moderate to large existing restoration • Fractured tooth/restoration • Moderate to large primary caries Contraindiations • Unable to adequately isolate the field • Parafunctional habits - bruxing, clenching, excessive wear

  16. Empress vs Gold Inlay/OnlayEmpress Advantages • ESTHETIC • Conservation of tooth structure (gold onlay vs porcelain inlay) • Less complicated cavity design?? Disadvantages • Expensive • Technique sensitive - bonding process • Abrasive to occluding dentition

  17. Empress vs PFMEmpress Advantages • Conservative cavity preparation • Foundation restoration may not be necessary • Less abrasive to occluding dentition • No metal collar Disadvantages • Expensive • Technique sensitive

  18. Cavity Preparation Design 1. Occlusal Depth/Cusp Reduction Occlusal Depth = 1.5 to 2.0 mm Cusp Reduction:Functional cusp = 1.5-2.0mm Nonfunction cusp = 1.5 mm 2. Internal/External Line Angles Rounded

  19. Cavity Preparation Design 3. Draw Degree of draw = approximately 12 to 15 degree 4. Bevel No bevel

  20. Mn first premolar- DO amalgam with fractured lingual cusp, deep pulpal floor Existing amalgam removed, making all walls divergent, smoothed all cavosurface margins

  21. Mx first molar - MOD amalgam with deep pulpal floor (4mm) Existing amalgam removed

  22. Proximal walls and gingival seats extended, occlusal wall divergent, clinical judgement was made to cover DL cusp (with shoulder) No cavosurface bevel on shoulder

  23. MOB amalgam on Mx first molar with deep pulpal floor Existing amalgam removed, make all walls divergent and smoothed all cavosurface margins

  24. Occl amalgam on Mn first molar, normal pulpal depth; patient complaining about pain on function- Dx: DB cusp fractured Patient’s occlusion

  25. Existing amalgam removed, DB cusp reduced by 2mm, all walls divergent No shoulder on DB cusp - WHY???

  26. MOD amalgam on Mn second molar with fractured Li cusp. Normal pulpal depth; all amaglam removed Proximal box divergent, Li cusp - smoothed cavosurface margin

  27. MOD amalgam on Mn first molar - occlusal fractured Shade selection BEFORE rubber dam; need dentin shade (match shade at gingival third) and overall shade

  28. Finished preparation; rubber dam removed; ready for impressioning; proximal box divergent, cusp reduction, buccal cusp with heavy bevel (no shoulder) Buccal view

  29. Wax up on working cast Special die for shade matching/staining - reason for taking the dentin shade

  30. Restoration on die/working cast

  31. Trying in under rubber dam; adjust proximal contact; do not adjust occlusal contact

  32. Cementation under rubber dam using resin cement; excess cement removed using cotton tip Excess resin cement removed from proximal/gingival margins using an explorer

  33. Rubber dam removed following cementation Adjust occlusion using fine diamond in high speed hand piece

  34. Laboratory Exercise - Mn first molar, MOD onlay preparation for porcelain

  35. Finished Preparation - MOD porcelain onlay preparation

  36. Restoration on die, back from laboratory

  37. Restoration seated under rubber dam Bu view after cementation

  38. Restoration on die, back from laboratory Restoration seated under rubber dam

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