Clinical Sequence for Onlays and Overlays
Partial-coverage indirect restorations — inlay, onlay, overlay/tabletop, vonlay.
Read this first — the vault has one onlay source, and it stops after temporisation
M6 Onlays is the only dedicated inlay/onlay lecture in the vault. It covers definitions, indications, cuspal coverage, preparation design, the pre-impression checklist, interim restoration, materials and longevity — and then stops. It contains no gingival retraction, no impression technique, no try-in sequence, no cementation protocol, no occlusal adjustment and no review.
This note contains onlay-specific evidence only. Every stage with no onlay-specific source is declared as an explicit gap below, pointing to Clinical Sequence for Crowns. Nothing has been silently borrowed from the crown teaching and relabelled as onlay guidance.
Definitions
Inlay — “Fixed intracoronal restorations that fit within the anatomic contour of the clinical crown.” It “Relies on the strength of the remaining tooth structure for support and retention” — the cusps must bear occlusal load independently, and “the inlay itself does not protect the cusps from fracture.” (Source: M6 Onlays — “Inlay”)
Onlay — “Partial-coverage restoration that restores one or more cusps and adjoining occlusal surfaces; or the entire occlusal surface. Retained by mechanical and/or adhesive means.” Designed “to protect weakened cusps from occlusal forces, preventing cracks and fractures. This is known as cuspal coverage.” (Source: M6 Onlays — “Onlay”)
Overlay / tabletop — “When an onlay covers the entire occlusal surface, it may be referred to as an overlay or tabletop.” (same)
Vonlay — full buccal cusp coverage, with the restoration margin on the cervical third (Source: M6 Onlays — “Position of buccal margin”).
Crown, for contrast — “covers five-eighths or more of the external tooth surface” (Source: 11 11. The Definitive Phase of Treatment - ClinicalKey.pdf (p.749-856) — “Full Coverage Indirect Restoration (Definitive Crown)”).
The distinguishing criterion
“The Extent of Tooth Structure Loss requiring replacement will define the need for an INLAY or ONLAY or a Full crown.” Onlay = “the need for tooth protection with CUSPAL COVERAGE whilst trying to avoid a traditional full crown.” (Source: M6 Onlays — “Onlay”)
“Partial crown” is never defined in any vault source — it appears only as a material-indication category in the ceramics literature. Do not treat it as a distinct entity on this evidence.
Why choose an onlay — the tissue-preservation argument
The 70% / 30% figure
“Approximately 70% of the volume of the clinical crown of a posterior tooth is removed for a full-crown preparation, whereas only about 30% is lost for an occlusal onlay, unless more tissue has already been lost.”
(Source: DMD2 L1 - Principles of Tooth Prep — “Clinical Research Reference”, quoting Edelhoff & Ahlers, “Occlusal onlays as a modern treatment concept for the reconstruction of severely worn occlusal surfaces”, Quintessence International, January 2018, DOI 10.3290/j.qi.a40482.)
Scope caveat: this figure is stated for the occlusal onlay in severely worn dentition, not for onlays in general. DMD2 L1 - Principles of Tooth Prep duplicates the citation verbatim under two headings — it is one reference, not two.
Independent dataset: “Onlays require an intermediate amount of tooth structure removal (falling between 27.2% for inlays and 67.5–75.6% for full crowns).” (Source: M6 Onlays — “Tooth structure removal in preparation designs”, Edelhoff & Sorensen 2002). Note this source gives no numeric value for the onlay itself, only that it sits between the two.
Rationale for cuspal coverage generally: “Covering the cusps with the restoration (as in an onlay or full crown) distributes occlusal forces over the entire tooth surface, preventing individual cusps from flexing and fracturing.” (Source: M1 PFM — “CUSPAL COVERAGE”)
Indications and contraindications
Onlay
Indications (Source: M6 Onlays — “Onlay” → “Indications”)
- Large cavities involving one or more cusps, but with enough sound enamel remaining for bonding
- Teeth with fractured or weakened cusps needing protection
- Replacement of defective large restorations
- Endodontically treated teeth “when sufficient tooth structure is still present” — structurally compromised by access cavity and previous decay
- Where a full crown is not indicated and tooth structure should be preserved — e.g. “when preparing axial walls would leave them excessively thin (e.g., less than 1mm). An onlay preserves more tooth structure in the cervical area”
- Replacement of a large MOD amalgam for aesthetics
Contraindications (same — “Contraindications”)
- Severely compromised teeth lacking sound enamel for predictable bonding — “Bonding to dentin and cementum is less predictable. In such cases, a restoration with mechanical retention (like a full crown) is preferred”
- Severe parafunction — “the high forces can fracture ceramic restorations. A stronger material like monolithic zirconia in a full crown design may be a better option”
Corroborated: “Patients who are prone to parafunctional habits such as clenching or clenching/grinding (bruxism) may have more clinical success with cast metal onlay restorations.” (Source: 11 11. The Definitive Phase of Treatment - ClinicalKey.pdf (p.749-856) — “Inlays and Onlays”)
Inlay
Indications — moderate cavities confined within the cusps; at least one sound marginal ridge; replacement of small defective occlusal restorations; where better marginal fit and durability than direct restoration is needed; where occlusal anatomy and contact points need precise reproduction, “especially for deep proximal boxes where direct placement is challenging” (Source: M6 Onlays — “Inlay” → “Indications”).
Contraindications — extensive destruction involving cusps; poor isolation or moisture control for bonding; MOD cavities with weak cusps (same).
Inlay or onlay?
The isthmus rule
“When the width of an intracoronal cavity exceeds 1/2 the distance of the cusp tips, an onlay or crown is probably more suitable.” “If the width of the occlusal isthmus is greater than half the distance between the cusp tips, the cusps are likely undermined and require onlay coverage for protection.” (Source: M6 Onlays — “Considerations for inlay vs. onlay”)
Endodontically treated teeth — “Cuspal coverage is needed for endodontically-treated tooth. These teeth should receive either an onlay or a full crown for cuspal protection. A small inlay is not justified, as a direct composite is more conservative if the tooth structure is sufficient.” (same)
Bonding substrate matters — consider “enamel bonding vs dentin bonding” and “variance in bonding to different qualities of dentin”. “Bonding to sclerotic dentin (often found under old amalgam fillings) is less predictable due to calcified tubules, resulting in lower bond strength. If bonding is compromised, the preparation may require more retentive features.” (same — “Things to consider”)
Cavity class mapping (Source: M6 Onlays — “Clinical rationale”):
| Cavity preparation | Recommended restoration |
|---|---|
| Class I | Composite, amalgam |
| Class II MO, DO | Composite, amalgam |
| Class II MOD | Composite, amalgam, indirect |
| Class II MODL, MODB | Amalgam, indirect |
| Multiple cusps missing | Indirect |
Indications for cuspal coverage
(Source: M6 Onlays — “Indications for Cuspal coverage”)
A. Tooth structure less than 2 mm — “If a cusp wall is less than 2mm in width, it is considered weak and should be covered with an onlay.”
B. Low quality enamel covering the cusp — “unsupported enamel are likely to fracture under occlusal load.”
C. Occlusal contacts on the margin of the preparation — “The margin of the restoration should not be placed directly at the occlusal contact point. The contact should ideally be on either the restoration or the natural tooth, away from the interface, to prevent fracture.”
Two different millimetre figures, two different questions
2 mm is the cuspal-coverage trigger — a cusp wall thinner than this needs covering. 1 mm is a different decision — axial walls that would be left thinner than 1 mm by a crown preparation are a reason to choose an onlay over a crown (Source: M6 Onlays — “Onlay” → “Indications”). Do not conflate them.
Supporting rationale for ETT — coronal restoration quality outweighs root filling quality for apical healing (Source: O3 Treatment Outcomes, Persistent Radiolucency’s, Options for Management — “Effect of Coronal Restorations”):
| Root filling | Good restoration | Poor restoration |
|---|---|---|
| Good | 91.4% | 44.1% |
| Poor | 69.6% | 18.1% |
This is a rationale for restoring ETT well; the source does not name onlays.
Where onlays sit in the cracked-tooth decision tree
Onlay is named at exactly one node — fractured cusp
“Fractured cusp — a complete fracture originating from the crown, usually involving a cusp and ending in a cervical area. Remove the loose segment and restore with a cuspal-coverage restoration (onlay/crown). Pulp is usually unaffected; prognosis is good.” (Source: How to Treat Cracked Teeth — “Management by Crack Type Along the Spectrum”)
Everywhere else this source specifies a crown, not an onlay:
- Framing: “not all cracked teeth need root canal treatment, but all cracked teeth need a crown.”
- Cracked tooth proper — the node the source calls “the key management problem” — is prescribed “Immediate occlusal reduction, definitive cuspal-coverage / full crown”. Onlay is not offered as an alternative here.
- The “Decision Summary” table and the Iowa Staging Index contain no onlay content at all; the restorative arm throughout is “RCT + crown”.
A claim that onlays are an accepted definitive restoration for cracked teeth is not supported by this source.
Preparation
Governing principle
Ceramics fail in tension
“The fundamental principle is that ceramics perform well under compression but fail under tension. Preparation design must accommodate this property.” (Source: M6 Onlays — “Principles of preparation for ceramic restorations”)
| Favourable | Unfavourable |
|---|---|
| Sufficient and even material thickness to distribute stress uniformly | Abrupt cross-sectional transition |
| Preparation follows the existing defect or restoration, removing only compromised structure | Sharp edges |
| Curved transitions — produce compressive stress on the internal surface | Box-style preparation — produces tensile stress on the internal surface |
| Simple geometry | Complex geometry |
| Gradual cross-sectional transition | — |
(Source: M6 Onlays — “Favorable designs” / “Unfavorable designs”)
Key preparation features
(Source: M6 Onlays — “Key preparation features for ceramic onlay and inlay”)
- No sharp internal line angles or points — only curved transitions
- Extension is dictated by the existing restoration or caries lesion
- All cavosurface angles sharp and well defined. Butt joint (90°)
- Avoid bevels, especially in occlusal contact areas — “A beveled or undefined margin makes it impossible for the lab to know where the restoration should end, leading to over-extension and thin, chippable ceramic edges”
- Smooth flowing margins; obtuse external line angles
- No additional retention features
- No unsupported tooth structure
- Gradual, not abrupt, transitions in material thickness
Why sharp internal angles break CAD/CAM
“Milling machines use burs with a minimum diameter (e.g., 1.0-1.5 mm) and cannot physically mill a sharp internal corner. The machine will compensate by over-milling the area, creating a void that will be filled with a thick layer of cement, compromising the fit and stress distribution of the final restoration.” (Source: M6 Onlays — “Key preparation features for ceramic onlay and inlay”)
Path of insertion
Single path of insertion, no undercuts, passive seating (Source: M6 Onlays — “Key preparation features for ceramic onlay and inlay”):
- Main buccal and lingual walls divergent towards the occlusal
- Axial walls of proximal boxes convergent towards the occlusal — “This is a critical feature to ensure a single path of draw”
- Traditional minimum bucco-lingual isthmus width: 2 mm
- “make sure that neighboring teeth are not blocking the path of insertion!” (same — “Path of insertion”)
Wall angles — the sources disagree, and one is internally confusing
M6 Onlays lists two angle bullets under one heading that read contradictory in isolation — “≥10 degrees of divergence on buccal and lingual walls” and “10 to 12 degrees of axial wall convergence”. They resolve as applying to different walls (main B/L walls divergent; proximal box axial walls convergent), per the note’s own callout.
Separately, Morphology driven of onlays preparation details (Veneziani 2017) gives “Convergent walls (6–10 degrees)” — which does not agree with M6’s 10–12°. Unreconciled in the vault.
Margin position
Buccal margin (Source: M6 Onlays — “Position of buccal margin”) — “Avoid contact points”:
| Design | Margin location |
|---|---|
| Ultraconservative buccal cusp coverage | Incisal third |
| Conventional buccal cusp coverage | Middle third |
| Full buccal cusp coverage (vonlay) | Cervical third |
“For aesthetics: the simplest and most ideal situation is for the restoration margins to be located in the incisal or cervical thirds.” (same)
Proximal margins and emergence profile — ensure “Absence of contact between the preparation and the adjacent teeth”; “Drop down the margins in order to obtain an optimal, natural proximal emergence profile of the future restoration.” (Source: M6 Onlays — “Proximal margins and emergence profile”)
Margin form (Source: M6 Onlays — “Margins”) — “No aspect of the margin should be located in an undercut and no unsupported enamel”:
| Accepted | Unacceptable |
|---|---|
| Deep chamfer, modified shoulder | Feather edge |
| Supra- or equigingival | Subgingival |
| — | “Gutter” margin |
Reduction specifications
(Source: Morphology driven of onlays preparation details — “Amount of reductions”, Veneziani 2017)
- Butt joint 1.2–1.5 mm
- 1 to 1.5 mm axial wall reduction
- 1.5 mm at least occlusal reduction for cuspal coverage
- Margin 1 mm if present
- Interproximal box: always
- Anatomical reduction of the occlusal surface
- Axial walls apically to the maximum contour line; inclined planes M–D and V–P (chamfer)
Reliability flags on the Veneziani specs
The source lists maxillary and mandibular blocks with identical content, and the maxillary heading is OCR-corrupted (“Maxillary mucospid and molars”). Treat the arch distinction as unreliable. The “Veneziani 2017” attribution is repeated three times as an orphaned line.
The 0.5 mm figure is not an onlay spec
“minimum 0.5 mm occlusal wall thickness” (Source: Contemporary Dental Ceramic Materials, A Review Chemical Composition, Physical and Mechanical Properties, Indications for Use — “Clinical Indications”) is stated for Lava Plus High Translucency Zirconia in a sentence about limited interocclusal space and tooth-preserving preparation. It is not presented as an onlay occlusal-thickness minimum. Do not cite it as one.
Preparation technique — morphology-driven vs conventional
(Source: M6 Onlays — “Tooth preparation” / “Preparation techniques”)
| Morphology-driven | (Old) conventional | |
|---|---|---|
| Geometry | Smooth flowing curves, rounded internal angles, simple geometry | Boxes, sharp angles, retentive grooves |
| Retention | Designed for adhesively bonded restorations | Designed for mechanical retention (cast gold onlays) |
| Stress | Minimises stress concentration, even distribution — ideal for ceramics | ”creates stress concentrations and is unfavorable for brittle ceramic materials” |
| Features | Immediate dentin sealing; deep margin elevation | Deep occlusal box; occlusal isthmus ≥2 mm; geometrical reduction |
| Suits | Bonded restorations | ”More suitable for indirect non-adhesive restorations” |
Immediate dentin sealing — rationale given as: “avoid unnecessary removal of tooth structure”; “protect the pulpodentinal structures from any contamination/disturbance during temporarization”; “stabilize and improve the adhesive interface quality.” (same — “Morphology driven preparation”)
Named but not described
Immediate dentin sealing and deep margin elevation are both listed as core to the morphology-driven method, and neither has any technique in the vault — no adhesive named, no timing, no depth limit, no indication threshold, no instruction on re-treating the sealed surface before bonding. If you need to perform either, this note cannot tell you how.
No stepwise preparation sequence exists
Neither technique is given as an ordered step list anywhere. M6 Onlays presents both as unordered feature sets; Morphology driven of onlays preparation details gives per-arch feature lists, also unordered. A step-by-step onlay preparation sequence is not in the vault and has not been invented here. The crown preparation sequence in Clinical Sequence for Crowns is not transferable — onlay preparation is defect-driven, not geometry-driven.
Checklist before impression or scanning
Verbatim (Source: M6 Onlays — “Checklist before impression or scanning”):
- Well defined sharp margins
- No undercuts, no sharp internal line angles
- Smooth surface
- Accessibility to all margins, especially subgingival margins
- Absence of contact between the prep margin and the adjacent tooth
- Adequate interocclusal space
Items 1–2 map onto the onlay-specific margin and internal-geometry rules above. Items 3–6 are generic indirect-preparation quality control; this lecture is simply the only place they are written down.
Interim restoration
(Source: M6 Onlays — “Interim restoration”) — this is the complete extent of the vault’s content:
| Option | Detail given |
|---|---|
| Non-cemented “semi-rigid” light-curing resin | Examples: Telio, Ivoclar. “Prep isolated with Vaseline at the periphery and over the axial walls before applying the material” |
| Self-curing material | ”such as Cavit W” — no technique given |
| Direct technique | ”Bis-Acryl composite” — no technique given |
Two of the three options have zero procedural detail
Only the semi-rigid option has any technique statement (the Vaseline isolation step). The self-curing and direct options are named materials with no steps, no timing and no cementation guidance.
The one link the sources draw between preparation and provisionalisation is that immediate dentin sealing exists partly to “protect the pulpodentinal structures from any contamination/disturbance during temporarization” (Source: M6 Onlays — “Morphology driven preparation”).
Materials, fabrication and longevity
Options (Source: M6 Onlays — “Material & fabrication methods”)
| Class | Materials | Fabrication |
|---|---|---|
| Precious alloys | Gold | Cast |
| Indirect composite | Polymer-based | CAD-CAM, chairside or lab |
| Ceramic | Feldspathic, leucite-reinforced, lithium disilicate, polymer-infiltrated, alumina-based, zirconia | Sintering, hot pressing, chairside and laboratory CAD/CAM |
“Survival rate: similar.” “Deterioration: Gold < Ceramic < Composite.” (same)
Longevity of ceramic onlays — Abduo & Sambrook, J Esthet Restor Dent 2018;30(3):193–215, systematic review (Source: M6 Onlays — “Longevity of ceramic onlays: a systematic review”):
- Survival 91–100% at 2–5 years; 71–98.5% beyond 5 years
- Causes of failure, in order: 1st ceramic fracture, 2nd debonding, 3rd caries
- Most common deterioration: loss of marginal integrity; second: margin discolouration
- “No indication that one ceramic material performs better than another, and the fabrication methods appear to minimally influence the ceramic onlay performance” — but “This conclusion should be interpreted with caution, as long-term, well-controlled clinical studies in prosthodontics are difficult to conduct and limited in number”
Annual failure rates — Hickel & Manhart 2001 (Source: M6 Onlays — “Longevity of restorations in posterior teeth and reasons for failure”):
| Restoration | Annual failure rate |
|---|---|
| Glass ionomers and derivatives | ~14% |
| Direct composites | ~8% |
| Ceramic restorations | ~7% |
| Amalgam | ~6% |
| Gold inlays and onlays | ~5% |
| CAD/CAM ceramic restorations | ~4% |
Main reasons for failure: secondary caries, fracture, marginal deficiencies, wear, post-operative sensitivity.
Ceramic onlay/inlay trade-offs (Source: M6 Onlays — “Ceramic onlay/inlay”)
Advantages — superior aesthetics; high wear resistance; excellent biocompatibility; resists staining; high compressive strength when properly bonded; bonds to tooth structure, reinforcing weakened cusps.
Disadvantages — brittle, prone to fracture if preparation or bonding is inadequate; more abrasive to opposing natural dentition than composite or gold; irreparable — “if fractured, usually requires replacement… as intraoral repair would require etching with hydrofluoric acid, which is not used clinically in the patient’s mouth”; more invasive than direct; technique-sensitive bonding; higher cost.
Material selection by flexural strength (Source: Contemporary Dental Ceramic Materials, A Review Chemical Composition, Physical and Mechanical Properties, Indications for Use — “Clinical Indications”)
- Feldspar-based (154 MPa) and leucite-reinforced (160 MPa) — “indicated for single tooth restorations such as veneers, inlays, onlays, partial crowns, and anterior and posterior crowns”
- Hybrid ceramics (150–240 MPa) — “can be used only for single tooth restorations such as veneers, inlays and onlays (Lava Ultimate), as well as for anterior and posterior crowns and implant-supported crowns (VITA Enamic and Cerasmart)”
- Lava Ultimate specifically — “not recommended for the production of crowns, but only for inlays, onlays and veneers”
Do not use this paper's tables
Table 1 of this review is OCR-shredded in the vault — composition percentages, flexural-strength values and indication lists appear as orphaned fragments with no row alignment. The paper is also internally inconsistent on hybrid ceramic flexural strength (150–240 vs 231 vs 242 vs 170.5 MPa for overlapping products). Use the prose “Clinical Indications” section quoted above; treat any figure read off the table as unverified.
Direct vs indirect composite (Source: M6 Onlays — “Direct vs. indirect composite restorations”) — indirect gains complete polymerisation, less porosity, no clinical shrinkage stress, better control of contours and contacts, better marginal adaptation and bond strength, and easier repair than ceramic. It costs more, is less conservative, and has less predictable colour stability and inferior mechanical properties than ceramic. Indirect CAD/CAM resin composites have “higher edge stability than ceramics, permitting restorations with very thin margins” (same — “CAD/CAM polymer-based material”).
Cementation
There is no onlay-scoped cementation protocol in the vault
The protocols that exist are product-scoped (Variolink, Panavia) or thickness-scoped, not restoration-scoped. Both threshold passages are quoted precisely below because both are routinely misread.
The “>2.5 mm” passage — this one does scope to onlays (Source: Dental Luting Cements An Updated Comprehensive Review — “3.5. Resin Cements”):
“Light-curing cements are indicated to cement ceramic or indirect composite restorations that are less than 1.5 mm thick… Dual-curing cements are recommended for ceramic and composite restorations with a thickness of 1.5–2.5 mm… Self-curing cements are used to cement the restorations that block light, such as zirconium oxide all-ceramic crowns and bridges, ceramic and composite inlays and onlays (>2.5 mm), adhesive fixed partial dentures, and metal constructions.”
The governing variable is restoration thickness, not restoration type:
| Restoration thickness | Curing mode |
|---|---|
| < 1.5 mm | Light cure |
| 1.5 – 2.5 mm | Dual cure |
| > 2.5 mm (includes thick inlays/onlays) | Self cure |
The “<2 mm” passage — inlays only, and only in one note (Source: DMD2 L3 - Biomaterials Dental Cements — “Variolink Esthetic LC Protocol (Inlays < 2mm)”). The threshold appears only in the heading; the protocol body contains no thickness statement.
Correction worth knowing
F7 Cements — “Variolink Esthetic LC” carries the same protocol in far greater detail across five phases, but with no inlay scoping and no thickness threshold anywhere, and its worked examples are crown-oriented (“have an assistant hold the crown down”). The “<2mm” inlay scoping exists only in DMD2 L3 - Biomaterials Dental Cements. The F7 protocol cannot be cited as inlay-specific.
Note also the two cut-offs disagree — Ivoclar’s heading says <2 mm for light cure, the 2023 review says <1.5 mm. Different sources, different boundaries; do not present them as one rule.
What the cement tables say about partial coverage
- “Ceramic inlay” and “ceramic veneer” are indicated for adhesive resin and self-etch adhesive resin only (classes 1 and 2), and contraindicated for classes 3–7 (GIC, reinforced ZOE, resin ionomer, zinc phosphate, zinc polycarboxylate). There is no onlay row. (Source: F7 Cements — “Summary table of what cement to use based on crown type”)
- Panavia F 2.0 names onlays inside its indication string — “Cementation of precious & semi-precious metal crowns, PFM crowns, bridges, inlays and onlays” — but the protocol given is not onlay-differentiated (Source: F7 Cements — “PANAVIA F 2.0 for Metal crowns/PFM crowns”)
The one onlay-specific post-cementation instruction in the vault
“Glass ceramic materials require resin cement luting as well as post-insertion attention to detail such as excess cement removal and careful polishing after refinement of occlusion.” (Source: 11 11. The Definitive Phase of Treatment - ClinicalKey.pdf (p.749-856) — “Inlays and Onlays”)
For the full Variolink, Panavia and RelyX protocols, surface treatment parameters and decontamination guidance, see Clinical Sequence for Crowns — “3.4 Cementation”. Apply them by material, not by restoration type, and select curing mode by the thickness table above.
Shade
The entire onlay-specific shade content in the vault is one line:
“Vita 3D Master - Classic: Indirect Restorations: Crowns, Onlays” (Source: W2 Clinical Applications — “Shade Guides at OHCWA”)
It names the guide. There is no onlay-specific shade-taking technique. The generic technique, timing controversy and lab-communication guidance are in Clinical Sequence for Crowns — “2.2 Shade”.
Declared gaps — stages with no onlay-specific source
Each of these was searched across all twelve onlay-relevant sources. The verdicts are definitive.
Gingival retraction — no onlay-specific content exists
Zero mentions of retraction cord, retraction paste, electrosurgery or any tissue-management method in any onlay source. M6 Onlays never addresses gingival management.
The only adjacent statement is the margin rule — “Supra or equigingival” accepted, “Subgingival” unacceptable (Source: M6 Onlays — “Margins”) — which reduces the need for retraction rather than describing it. This is a real advantage of onlay design, not a substitute for guidance.
→ If retraction is needed, see Clinical Sequence for Crowns — “2.7 Soft tissue management and definitive impression”. Be aware you are applying crown teaching.
Definitive impression technique — no onlay-specific content exists
M6 Onlays mentions impression only as an appointment item (“Tooth preparation + impression/scan + temporarization”). No material choice, no tray selection, no one-step/two-step, no wash technique. The pre-impression checklist above is preparation verification, not impression technique.
→ See Clinical Sequence for Crowns — “2.7 Soft tissue management and definitive impression”.
Digital scanning — no onlay-specific content exists
Only the word “scan” in two appointment-sequence lines and in the checklist title. No scan path, no margin-capture guidance, nothing distinguishing the digital workflow for partial coverage.
→ See Clinical Sequence for Crowns — “2.7 Soft tissue management and definitive impression”.
Laboratory prescription — no onlay-specific content exists
No lab-slip content, no shade/material/margin communication instructions for onlays. Two indirect touches only: the prep rule “Avoid bevels… makes it impossible for the lab to know where the restoration should end” (Source: M6 Onlays — “Key preparation features for ceramic onlay and inlay”), and W2 Clinical Applications — “Consult with the Lab”, which is generic and never names onlays.
→ See Clinical Sequence for Crowns — “2.11 Dispatch to the laboratory”, which is itself a declared gap.
Try-in sequence — no onlay-specific sequence exists
M6 Onlays lists “Try-in of the final restoration” as a bullet with no procedure. The try-in sequence in F7 Cements — “Phase 1: Try-In and Assessment” is product-scoped to Variolink, not restoration-scoped, and its wording is crown-oriented. The textbook adds one generic line: “The final restoration is tried in the mouth and, after occlusion and proximal contacts have been adjusted, is cemented in place” (Source: 11 11. The Definitive Phase of Treatment - ClinicalKey.pdf (p.749-856) — “Inlays and Onlays”).
Specifically missing: seating-force cautions for unbonded ceramic over unsupported cusps, and whether the crown seating order (proximal → internal → marginal) transfers to partial coverage.
→ See Clinical Sequence for Crowns — “3.2 Seat the crown — in this order”, applying judgement.
Occlusal adjustment — no onlay-specific content exists
W2 Clinical Applications — “Adjusting Occlusion” is entirely generic and never mentions onlays. M6 Onlays has occlusion-related preparation rules — occlusal contacts off the margin, adequate interocclusal space — but no post-cementation adjustment guidance, nothing on adjusting bonded ceramic, and no repolishing sequence.
The nearest onlay-specific fragment is the textbook’s “careful polishing after refinement of occlusion” for glass ceramics, quoted under Cementation.
→ See Clinical Sequence for Crowns — “3.5 Post-cementation”.
Post-operative review and recall — no onlay-specific content exists
No recall interval, no review protocol, no maintenance guidance for onlays anywhere. The Abduo deterioration data tells you what to look for at review (marginal integrity, margin discolouration, surface roughness, colour match, anatomical form) but never when. The “~6 months” recall in How to Treat Cracked Teeth is for cracked teeth under crowns, not onlays.
→ See Clinical Sequence for Crowns — “Visit 4 — Post-operative review (1–2 weeks)”.
Isolation for onlay bonding — no onlay-specific content exists
“Poor isolation or moisture control for bonding” appears only as an inlay contraindication. F7 Cements mentions rubber dam once inside the generic Variolink protocol. Given that onlay retention is substantially adhesive, this is a conspicuous gap.
Source notes
- M6 Onlays is the single point of failure for this note. It is the only dedicated inlay/onlay lecture in the vault. Six of the ten clinical-sequence stages have no onlay source at all, which is why this note is shorter than Clinical Sequence for Crowns by design rather than by omission.
- Contemporary Dental Ceramic Materials, A Review Chemical Composition, Physical and Mechanical Properties, Indications for Use has an OCR-shredded Table 1 and internally inconsistent hybrid-ceramic flexural strengths. Prose only.
- Morphology driven of onlays preparation details lists maxillary and mandibular specs identically and has an OCR-corrupted heading. Arch distinction unreliable.
- 11 11. The Definitive Phase of Treatment - ClinicalKey.pdf (p.749-856) — the onlay paragraph is truncated mid-sentence in the vault (“An onlay is”). Text is lost; do not treat that section as complete.
- DMD2 L1 - Principles of Tooth Prep duplicates the Edelhoff 70%/30% reference verbatim under two headings. One citation, not two.
- The empty scaffold folders
Reference/Restorative Dentistry/Resources/Indirect Restorations/Onlays/and/Inlays/exist but contain no notes. This note lives under Fixed Prosthodontics alongside Clinical Sequence for Crowns and Molar Crown and Bridge Preparation Tips.