Onlay and Overlay Template

Chairside Form 26 for a partial-coverage bonded restoration (inlay / onlay / overlay) on [tooth __], [material: lithium disilicate / composite / feldspathic]. Extracted from Clinical Sequence for Onlays and Overlays. Onlay-specific stages only; several stages defer to Clinical Sequence for Crowns — see the gap callout below.

Two signatures required

Form 26 = reconstructive phase. You need 2 signatures — prosth specialist AND clinic coordinators. No aesthetic work on this form.

Stages with NO onlay-specific vault source — each defers to Clinical Sequence for Crowns

M6 Onlays is the only dedicated inlay/onlay lecture in the vault; it stops after temporisation. The following stages have no onlay-specific evidence and borrow crown teaching — apply with awareness:

• Gingival retraction — no onlay mentions of cord/paste/electrosurgery (onlay margins are supra/equigingival by design, which reduces the need). → Crowns “2.7”
• Definitive impression technique — impression appears only as an appointment item; no material/tray/wash technique. → Crowns “2.7”
• Digital scanning — no scan path or margin-capture guidance. → Crowns “2.7”
• Laboratory prescription — no onlay lab-slip/shade/material communication. → Crowns “2.11” (itself a declared gap)
• Try-in sequence — no procedure; missing seating-force cautions for unbonded ceramic over unsupported cusps. → Crowns “3.2”
• Occlusal adjustment — no onlay post-cementation adjustment, nothing on adjusting bonded ceramic. → Crowns “3.5”
• Post-operative review & recall — no interval, protocol or maintenance for onlays. → Crowns “Visit 4”
• Isolation for onlay bonding — appears only as an inlay contraindication; conspicuous gap given adhesive retention

Coverage decision

• Inlay — intracoronal, fits within the anatomic contour; relies on remaining tooth for support; does not protect cusps.
• Onlay — partial coverage; restores one or more cusps + adjoining occlusal surface; provides cuspal coverage to protect weakened cusps.
• Overlay / tabletop — an onlay covering the entire occlusal surface.
• Vonlay — full buccal cusp coverage, margin on the cervical third.

Cuspal-coverage triggers (M6 Onlays):

• Cusp wall < 2 mm wide → weak, cover with an onlay
• Low-quality / unsupported enamel over the cusp → fractures under load
• Occlusal contact on the prep margin → shift coverage so the contact sits on tooth or restoration, never the interface
• Isthmus width > ½ the intercuspal (cusp-tip) distance → cusps undermined → onlay or crown, not inlay
• Parafunction / bruxism → prefer a full crown (monolithic zirconia); high forces fracture bonded ceramic

Don't conflate the two millimetre figures

2 mm is the cuspal-coverage trigger (cusp wall thinner than this → cover). 1 mm is a different decision — axial walls a crown would leave < 1 mm favour an onlay over a crown.

Appointment 1 — Prep & impression

• Local anaesthesia
• Shade — Vita 3D Master (W2 Clinical Applications); take wet, before prep/dehydration. Generic shade technique/timing → Clinical Sequence for Crowns “2.2 Shade” (declared onlay gap)
• Defect-driven preparation (extent dictated by the existing restoration/caries; remove only compromised structure):
  • Butt joint (90°), 1.2–1.5 mm; occlusal ≥ 1.5 mm where cuspal coverage is needed
  • No undercuts, single path of insertion (main B/L walls divergent occlusally; proximal-box axial walls convergent); passive seating; check neighbours don’t block the path
  • Rounded internal angles — no sharp internal line angles (milling burs min. 1.0–1.5 mm dia. cannot cut a sharp internal corner → over-milling/void)
  • Margins supra- or equigingival (subgingival unacceptable); deep chamfer / modified shoulder; no unsupported enamel; no margin in an undercut
  • AVOID bevels, especially at occlusal contacts (undefined end → over-extension, thin chippable ceramic edge)
  • No additional retention features

• Immediate dentin sealing (morphology-driven method) — protects the pulpo-dentinal complex during temporisation, stabilises the adhesive interface
• Pre-impression checklist (M6 Onlays):
  1. Well-defined sharp margins
  2. No undercuts, no sharp internal line angles
  3. Smooth surface
  4. Accessibility to all margins, especially subgingival
  5. Absence of contact between the prep margin and the adjacent tooth
  6. Adequate interocclusal space
• Interim restoration — Telio / Ivoclar (non-cemented “semi-rigid” light-cure resin; isolate prep with Vaseline at the periphery and over the axial walls before applying); or Cavit W (self-cure); or bis-acryl composite (direct)
• Impression & retraction → DEFER to Clinical Sequence for Crowns “2.7” (declared onlay gap — you are applying crown teaching)
• Send to lab (material justification, shade; lab prescription is itself a declared gap → Clinical Sequence for Crowns “2.11”)

+1.5 — On receiving labwork (before Appt 2)

Check on the die/master cast: marginal integrity, internal fit, seating on die, proximal contacts, occlusion on the articulator, external contour/shade/surface. Because onlay ceramic is thin and brittle, confirm even material thickness and no thin/chippable margins before the patient is seated.

Appointment 2 — Try-in & adhesive cementation

• Try-in (fit, margins, proximal contacts, colour). Onlay-specific try-in sequence is a declared gap — apply the crown seating order (proximal → internal → marginal) with judgement, Clinical Sequence for Crowns “3.2”
• ISOLATION is critical — rubber dam. Onlay retention is substantially adhesive
• Curing mode by restoration thickness (governing variable is thickness, not type):
  • < 1.5 mm → light cure
  • 1.5–2.5 mm → dual cure
  • > 2.5 mm (thick, light-blocking) → self cure
• Glass-ceramic surface treatment: HF etch intaglio (often lab-done; ~9%; e.max 20 s / Empress 60 s) → silane (Monobond Plus: react 60 s, disperse with air, do not rinse). Zirconia: no silane, MDP cement, ~1 bar airborne abrasion
• Decontaminate after try-in — Ivoclean / Katana Cleaner
• Resin cement (Variolink Esthetic / Multilink for glass-ceramic; Panavia / MDP for zirconia). Full Variolink/Panavia/RelyX protocols → Clinical Sequence for Crowns “3.4 Cementation” — apply by material, curing mode by the thickness table
• Excess removal (plastic instrument; floss interproximally, pull out to the side, never up through the contact) → polish AFTER refinement of occlusion (the one onlay-specific post-cementation instruction — glass ceramics need “excess cement removal and careful polishing after refinement of occlusion”)
• Post-cementation bitewing for residual subgingival cement
• Occlusal adjustment → DEFER to Clinical Sequence for Crowns “3.5” (declared onlay gap — nothing on adjusting bonded ceramic)

Copy-pastable checklist

ONLAY / OVERLAY — [tooth __] — [material: lithium disilicate / composite / feldspathic]
COVERAGE
- Provide cuspal coverage when the cusp wall is less than 2 mm wide, when there is unsupported enamel over the cusp, when an occlusal contact sits on the prep margin, or when the isthmus is wider than half the intercuspal width.
- In parafunction, prefer a full crown.

APPOINTMENT 1 — Prep and impression
- Give LA.
- Take the shade with Vita 3D Master, with the tooth wet, before the prep. Record thirds and in-between values, for example A1.5.
- Prepare to the defect and remove only compromised structure.
    - Use a butt joint at 90 degrees, 1.2-1.5 mm deep, and at least 1.5 mm occlusally under cuspal coverage.
    - Leave no undercuts, a single path of insertion, and rounded internal angles.
    - Keep the margins supragingival or equigingival, with a deep chamfer or modified shoulder, and leave no unsupported enamel.
    - AVOID bevels, especially at occlusal contacts.
- Place an immediate dentin seal. It protects the pulp and dentine during temporisation and stabilises the adhesive interface.
- Check before impressing that the margins are sharp and smooth, that there are no undercuts and no sharp internal angles, that every margin is accessible, that the margin does not contact the adjacent tooth, and that the interocclusal space is adequate.
- Make the interim restoration in bis-acryl.
- Use double cord retraction.
- Take a dual-phase PVS impression, with light body on the margins and heavy body in the tray. Remove the top cord before injecting.
- Take an alginate impression of the opposing arch and a bite registration.
- Dispatch the case to the lab with the material justification and the shade.

+1.5 LAB CHECK (before Appt 2)
- Check marginal integrity, internal fit, seating on the die, proximal contacts, and the occlusion on the articulator. Check the contour, shade, and surface.
- Confirm the thickness is EVEN and that there are no thin or chippable margins, because onlay ceramic is brittle.

APPOINTMENT 2 — Try-in and adhesive cementation
- Try the restoration in and check the fit, the margins, the contacts, and the colour.
- Seat it proximal first, then internal, then marginal. Be gentle, because the ceramic is unbonded over unsupported cusps.
- ISOLATION IS CRITICAL. Use rubber dam, because retention here is adhesive.
- Choose the curing mode by thickness. Light cure at less than 1.5 mm, dual cure at 1.5-2.5 mm, and self cure at more than 2.5 mm.
- For glass-ceramic, HF etch at about 9%, using 20 seconds for e.max, then apply silane (Monobond Plus, react for 60 seconds, do not rinse).
- For zirconia, use no silane, use MDP, and airborne abrade at about 1 bar.
- Decontaminate the intaglio after try-in with Ivoclean or Katana Cleaner.
- For glass-ceramic, cement with Variolink or Multilink. Tack cure for 2 seconds, run Liquid Strip at the margins, then final cure for 10 seconds per surface.
- For zirconia, cement with Panavia, using ED Primer, MDP, and Oxyguard.
- Remove excess cement with a plastic instrument, and floss it out sideways. Polish AFTER the occlusion has been refined.
- Take a post-cementation bitewing to check for subgingival cement.
- Adjust the occlusion with articulating paper, blue for centric and red for eccentric. Adjust the inclines, not the functional cusp tips, then re-polish.