ceramic indirect restoration

Direct Restoration

Restorations that are placed directly in the mouth after tooth preparation.

Material is applied in a tooth preparation and then shaped and cured inside the tooth.

Typically used for small to moderate defects.

Indirect Restoration

Restorations that are fabricated outside the mouth (usually in a dental lab or using CAD/CAM technology).

Requires a final impression (traditional or digital) to create a customized restoration

Used for larger defects or when additional strength is required.

ceramic indirect restoration

INLAY/ONLAY

Single Crown

Fixed Partial Denture (F.P.D)

Veneers

materials for indirect inlay/onlay

Porcelain/Ceramic → LEUCITE/FELDSPATHIC (anteriors)

COMPOSITE

most commonly used:

LITHIUM DISILICATE (e-Max)

Zirconia

properties of the different materials used for inlay/onlay

Indications

Esthetic areas (anterior teeth) → E. max + feldspathic

Moderate to large restorations requiring mechanical and esthetic properties → emax + zirconia

Fractured or worn dentition

Replacement of old composite/amalgam

Patients with good oral hygiene and low caries risk

Contraindications

Bruxism or heavy occlusion (relative for feldspathic)

Poor moisture control (affects bonding)

Inadequate enamel for bonding

Deep subgingival margins

Patients with high caries risk

An Inlay/Onlay can be used instead of a direct restoration for patients with

a low caries risk, when higher strength of material is needed (heavy occlusion/metal), or when superior control of contours and contacts are desired.

An inlay requires ample supporting dentin in the facial and lingual surfaces

Onlay

allows the damaged occlusal surface to be restored in the most conservative
manner, compared to a full coverage crown

Objectives of tooth preparation

Preserve Tooth Structure: Aim for minimal reduction to maintain strength and
vitality.

Ensure Adequate Thickness: Provide sufficient space for the ceramic material to
withstand occlusal forces.

Smooth Transitions: Create rounded internal line angles to reduce stress
concentration.

Appropriate Margins: Use well-defined margins suitable for the specific restoration
type.

Ceramic Inlay Restorations

Occlusal Reduction: 1.5–2.0 mm deep for sufficient ceramic thickness.

Isthmus Width: Minimum 2.0 mm for strength and resistance to fracture.

Wall Divergence: 6°–10°

Internal Angles: Rounded (no sharp internal line angles).

Cavosurface Margin: Use a butt joint or light bevel, no sharp shoulders.

Exit Angles: Avoid acute exit angles to prevent marginal chipping.

Taper: Axio-pulp lines angles rounded

Break interproximal contact. Perio probe tip will just fit between adjacent tooth and prepared CSM at facial, lingual and gingival margins. When the interproximal contact is not broken, it is difficult to capture the margin with the final impression

Ceramic onlay Restorations

Functional Cusp Reduction: 1.5–2.0 mm reduction for molars and premolars.

Non-functional Cusp: 1.0–1.5 mm if covered.

Occlusal and Proximal Boxes: Extend 1–1.5 mm into proximal surfaces with smooth transitions.

Margin Design: Use butt joint or rounded shoulder. No feathered edges.

Axial Wall Divergence: Maintain 6°–10° taper for draw.

Avoid Sharp Margins: Sharp margins increase risk of ceramic fracture.

Internal Finish: All line angles rounded and smooth.

Ceramic Inlay preparation

Evaluate occlusal contacts relationships with articulating paper

Margins of the restorations should not be at the centric contact

Rubber Dam Isolation

Outline form is usually dictated by

the existing restoration and caries

Removing existing restoration and caries.

internal outline

No undercuts: If necessary, undercuts can be blocked with composite or glass ionomer.

If the undercut leaves unsupportive enamel, the enamel must be removed and preparation design modify

Walls: Facial, lingual, mesial or distal: 6º-8º wall divergently tapered is optimum for internal adaptation and margin fit.

Over-tapering leads to thinner occlusal margins and increased margin stress as the margin approaches the cusp.

proximal box

Axio-pulpal line angle should be rounded.

Gingival wall parallel occlusal plane, no J-CSM.

No undercuts in proximal portion of walls in the box.

Proximal box (Inlay) and extension of box (onlay)
Onlay : The slopping ramp between the proximal box and the extension of box should be smooth.

Advantages of ceramic

Excellent esthetics

Biocompatibility

High strength (lithium disilicate, zirconia)

Color stability

Disadvantages of ceramic

Brittle (especially feldspathic porcelain)

Technique-sensitive bonding

Requires enamel for optimal adhesion

Higher cost compared to composites

Cementation resin based luting agents: Etchable ceramics

Hydrofluoric acid etch

Silane coupling agent

Resin adhesive cement

e.g., lithium disilicate

Cementation resin based luting agents: non-etchable ceramics

Sandblasting

MDP-containing primers

Self-adhesive or resin cements

ex: zirconia