Crown Template

Hub for full-coverage crowns on Form 26. The chairside sheets live in one file per material — this note is the decision tree that gets you to the right one, and the place where the cross-material comparisons live.

Two signatures required

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

Pick your sheet

Material	Sheet	One-line case for it
Lithium disilicate	E.max Crown Template	Best aesthetics; the reference for anterior single units. Bonded, not cemented.
Metal-ceramic	PFM Crown Template	Strength plus acceptable aesthetics; long spans; reduced-height preps.
Zirconia	Zirconia Crown Template	Highest strength; where an all-ceramic has to survive load. High-translucency grades now exist for the anterior.
Full gold	Full-Metal Crown Template	Posterior only. Most conservative prep, best for short crowns and bruxers.

Related: Crown with Post and Core Template for an endodontically treated tooth needing a post, PFM Survey Crown Template for a crown contoured to receive an RPD.

Material selection — indications and contraindications

Two caveats on this table

No lecture in the vault gives a zirconia-specific or e.max-specific indication list — F2 Ceramics gives one generic “all-ceramic” list covering both, so cells marked (generic all-ceramic) apply to e.max and zirconia alike. The full-gold contraindication list in F1 FullMetalCrowns is truncated mid-sentence in the source; only “high aesthetic need” survives.

	E.max	PFM	Zirconia	Full gold
Flexural strength	360–400 MPa	No figure recorded	900–1200 MPa; transformation toughening (“ceramic steel”)	No figure; alloy casts in 0.3 mm section
Indications	High aesthetic demand; metal allergy; more conservative than PFM. Single units anterior and posterior; 3-unit bridges only to the 2nd premolar as terminal abutment	Strength and aesthetics together; posterior crowns and bridges; long-span FDPs; reduced-height preps where all-ceramic lacks support; heavy load; RPD and FPD abutments	(generic all-ceramic) plus implant abutments, telescope crowns, cantilever and adhesive bridges, long spans up to 14 units	Short clinical crowns; maximum retention and resistance; high displacement forces; limited occlusal clearance; heavy bruxers
Contraindications	Heavy bruxers; heavy occlusal forces; parafunction; overly short clinical crowns. Brittle unsupported — do not exceed 2 mm. At ~1 mm thickness the abutment colour shows through	Metal allergy (esp. nickel/cobalt); maximum-translucency cases; minimal reduction and young teeth with large pulps; deep bite or limited interocclusal space; unprotected parafunction	(generic all-ceramic). Plus low-temperature degradation — overloading in parafunction, thermal shock, long-term water contact	High aesthetic need — any tooth visible in the smile
Prepare to (OCHWA)	Incisal 1.5 anterior; occlusal 2 functional / 1.5 non-functional; axial 1; margin 1	Incisal/occlusal 2 anterior; 2 functional / 1.5 non-functional; axial 1.5; margin 1.5 shoulder	Same as e.max — no zirconia row exists; confirm with the lab	Occlusal 1.5 functional / 1 non-functional; axial 1; chamfer 0.5–1. The most conservative of the four
Aesthetic zone	Best	Compromise — less translucent, risk of a dark margin	Conditional — high-translucency grades only	Not suitable
Parafunction	Contraindicated	Indicated with a metal occlusal/palatal surface or a splint; contraindicated unprotected	Caution — strongest, but parafunction is a documented degradation trigger	Best of the four; wears at a rate similar to enamel
Short clinical crown	Contraindicated	Usable, but 1.5 mm axial eats wall height	Generic all-ceramic caution; far larger strength margin	Best — 1.0–1.5 mm occlusal vs ~2.0 mm for ceramics preserves wall height
Antagonist wear	Gentlest of the ceramics	Porcelain abrades enamel if not polished or glazed; a metal occlusal surface is kinder	Polish, never leave glazed or adjusted-unpolished. Published findings conflict	Best — wears like enamel, does not chip
Bond or cement?	Adhesive, effectively mandatory — HF-etchable, and adhesion carries the load	Either — every cement class is indicated for a metal-ceramic crown	Self-adhesive or conventional. Cannot be HF-etched — sandblast plus MDP, no silane	Conventional is the textbook answer; at OCHWA it is resin (see below)
Cost	—	Less expensive than full gold, more than monolithic ceramic	Grouped with the cheaper options	Most expensive

Sources: OCHWA Crown Reduction Guidelines (reduction figures), F1 FullMetalCrowns, F2 Ceramics, M2 PFM Prep, F7 Cements, DMD2 L3 - Biomaterials Dental Cements. Zirconia antagonist wear is not covered anywhere in the vault — that row is external.

There are no per-material survival figures here

The only failure-rate data in the vault is indirect vs direct (ceramic 1.9%, composite 2.2%, amalgam 3.0% annual) and does not break down by crown material. There is no 5- or 10-year survival figure for gold, PFM, e.max or zirconia individually, and no PFM chipping rate. Do not quote one.

Cement decision tree

What OCHWA actually stocks

Permanent: RelyX Unicem 2, Panavia F 2.0, Variolink Esthetic — the LC (light-cure) version only. Provisional: TempoCem. Temp crown: Luxatemp. Bite registration: Regisil. That LC-only limit matters: it is why a posterior e.max crown is cemented with Panavia here rather than Variolink. Source: Coals 3. Definitive (Reconstructive phase treatment) — “these are OCHWA specific” — corroborated by F7 Cements on RelyX Unicem 2: “Another cement available in clinic”. Zinc phosphate is not on that list, which is why no sheet here prescribes it.

Material	Cement	Why
E.max, anterior or under 1.5 mm	Variolink Esthetic LC	Adhesion carries the load — adhesive resin gave 306.6 N mean failure load vs 94.7 N for GIC. Light cures reliably through a thin, translucent restoration
E.max, posterior crown	Panavia F 2.0	Too thick to light-cure through, and OCHWA has no Variolink Dual Cure. Panavia dual-cures with an OXYGUARD II self-cure route and is still a true adhesive cement — unlike self-adhesive RelyX, which gives up the adhesion e.max depends on. HF etch and silane the intaglio as usual
Zirconia	Panavia F 2.0 (RelyX Unicem 2 acceptable)	MDP bonds to the oxide layer; no glassy phase to etch. MDP resin 16.9 MPa shear bond to dentine vs RMGI 9.2, GIC 3.4
PFM	Panavia F 2.0 + Alloy Primer	Sandblasted intaglio plus MDP; the only in-clinic cement with metal-primer chemistry
Full gold	Panavia F 2.0 + Alloy Primer (RelyX Unicem 2 fallback)	Zinc phosphate is not stocked. Panavia’s own indication names precious and semi-precious metal crowns, and a cast crown carries no cement-class contraindication
Fibre post	RelyX Unicem 2 (thin tip)	Lower polymerisation shrinkage matters in the root-canal C-factor

The three cements side by side

	Panavia F 2.0	RelyX Unicem 2	Variolink Esthetic
Class	Resin with 10-MDP, dual cure	Self-adhesive resin, dual cure	Adhesive resin, light or dual cure
Bonding	MDP phosphate to metal oxides; MDP-Ca salts to dentine, plus sandblast retention	Self-etch in one step — no etch, no bond, no primer	Etch and bond the tooth; HF etch and silane the ceramic
Handling catch	ED PRIMER II goes on the TOOTH and starts the set — 30 s, then air dry. Cement goes inside the crown, never on the tooth	Dry with 2–3 bursts of air, do not overdry. Thick tip for crowns, thin for posts	Most steps and most moisture-sensitive. Monobond Plus reacts 60 s and is never rinsed
Cure	20 s per surface light, or OXYGUARD II and 3 min self-cure	Tack, remove excess, final cure; sets ~6 min	Tack 2 s, remove excess, 10 s per surface through Liquid Strip
Weakness	Technique-heavy; cured excess is hard to remove	Weaker bond to enamel — a selective enamel etch may help	Needs rubber dam and time

Curing depth — the rule that decides which cement you reach for

Restoration	Curing mode
Translucent, under 1.5 mm	Light-cure acceptable
1.5–2.5 mm	Dual-cure
Zirconia, and anything thick or opaque	Self- or dual-cure — light cannot penetrate

The practical consequence: a posterior crown is built to 2 mm on the functional cusp and 1.5 mm on the non-functional, so it sits past the light-cure ceiling. DMD2 L3 - Biomaterials Dental Cements scopes its light-cure protocol as “Variolink Esthetic LC Protocol (Inlays < 2 mm)” for exactly this reason.

Because OCHWA stocks only Variolink Esthetic LC, there is no dual-cure Variolink to switch to — so the cement itself changes: Variolink Esthetic LC for anteriors, veneers and thin inlays; Panavia F 2.0 for posterior e.max crowns. Panavia is the right second cement rather than RelyX because it is still a true adhesive protocol (tooth primed, intaglio etched and silanated), and it carries a guaranteed self-cure route through OXYGUARD II when light cannot reach.

When RelyX Unicem 2 is the right call — and when it is not

Use it when:

• Zirconia, where self-adhesive cementation is a defensible protocol and fracture load is largely independent of cement type.
• Fibre posts — lower polymerisation shrinkage matters against the root-canal C-factor. Use the thin tip; the thick tip is for crowns.
• Moisture control is poor and a multi-step adhesive protocol would be compromised — it is dual-cure, so it sets through bulk regardless of light access.
• Speed matters or the case is straightforward: no etch, no bond, no primer, one step.
• Full metal and PFM as the fallback when the Panavia kit is incomplete.

Do not reach for it when:

• Lithium disilicate is the material. e.max depends on adhesion for its fatigue and load-bearing behaviour, and the vault’s own data favours a true adhesive protocol. On a posterior e.max crown the answer is Panavia, not RelyX — both cure through bulk, but only Panavia keeps the adhesive protocol. RelyX is the fallback if the Panavia kit is incomplete, and if you use it, still HF etch and silane the intaglio — do not treat it as a self-adhesive shortcut.
• The bond lands mostly on enamel. F7 warns that limited demineralisation and infiltration “may not have good bond strength to enamel”; a selective enamel etch helps.
• Retention is already poor — a short or over-tapered prep needs an adhesive or self-etch adhesive resin (cement classes 1–2), not a compromise.
• Veneers or ceramic inlays — classes 1 and 2 only.

Whatever the cement: decontaminate the intaglio after try-in with Ivoclean or Katana Cleaner, and take a post-cementation bitewing for subgingival remnants.

Impression decision

Available at OCHWA

PVS and polyether, plus Trios 3 / 4 / 5 scanners. The house crown protocol is light body PVS on the prep, medium or heavy body in a custom tray, opposing arch in alginate, bite registration with Regisil. VPES is not stocked — it appears below for comparison only.

	Digital scan (Trios)	PVS	Polyether	VPES
Crown accuracy	Equal to conventional for crowns and short spans	Best elastic recovery; shrinkage ≈ 0.15%, the lowest	Second-best elastic recovery; shrinkage ≈ 0.2%	No independent figure
Full arch	Worse than conventional — stitching error; validated to about ten units	Acceptable; stiff material is a problem on mobile teeth	Stiffest of all — hardest to remove	—
Moisture	Cannot see through blood, saliva or tissue at all	Effectively hydrophobic; needs a dry field	Hydrophilic; tolerates moisture best	Hydrophilic, stays so after set
Tear strength	n/a	Moderate	Highest — best subgingival detail without tearing	High
Contamination	Double-layer artefact if the scanner loses its place	Latex inhibits the set — keep latex off the material, tissues, tray and retraction cord. Use nitrile	Unaffected by latex	—
Time	Full arch 15–20 s scanning; whole procedure ~248 s vs ~605 s conventional	4–5 min set; wait 30 min before pouring	~5 min set; disinfect 10 min, then pour	—
Key limitation	Subgingival margins. Beyond 0.5–1.0 mm subgingival, take a conventional impression. Review preps in monochrome	Moisture sensitivity and latex inhibition	Stiffness on undercuts and mobile teeth	Not stocked

Technique verdicts, all from F6 Soft Tissue Impressions: dual-phase light plus heavy body in one stage is the recommended technique; two-step with putty has good accuracy; one-step putty wash is significantly less accurate; monophase is not recommended (lower definition); triple tray is not recommended (distortion).

Shared prep principles

These apply to every material — the per-material numbers live on the sheets.

• Taper vs TOC. Taper is the angle of one axial wall; total occlusal convergence is between two opposing walls, so TOC = 2 × taper. Ideal TOC is 6–12°. The shorter the axial walls, the more parallel they must be.
• Margin design by type. Chamfer for metal; shoulder or modified shoulder where porcelain needs bulk; feather edge is contraindicated in most cases.
• Margin placement. Supragingival wherever possible. If subgingival, stay intracrevicular — about 0.7 mm, and never violate the biologic width.
• Undercut check. View from directly above with one eye closed: every part of the margin must be visible. On the cast, check from about 30 cm.
• Functional cusps are maxillary lingual and mandibular buccal — these take the deeper reduction and the functional cusp bevel.
• Auxiliary grooves or boxes only when retention is poor: 1 mm deep, 1 mm above the margin, mid-buccal, parallel to the path of insertion.
• Volume cost. About 70% of the clinical crown volume of a posterior tooth is removed for a full crown, against about 30% for an occlusal onlay — worth weighing before committing to full coverage.

Sources and their weight

• OCHWA Crown Reduction Guidelines — the reduction figures every sheet prepares to. Authoritative at this clinic; it is a teaching table, not published literature, so do not cite it as evidence.
• M2 PFM Prep carries a real bibliography (Shillingburg; Rosenstiel; Goodacre 2001; Glossary of Prosthodontic Terms 9th ed). DMD2 L1 - Principles of Tooth Prep carries DOIs.
• Strongest citable sources in the vault: Heboyan et al., Dental Luting Cements: An Updated Comprehensive Review, Molecules 2023;28:1619 (DOI 10.3390/molecules28041619); Bajraktarova-Valjakova et al. 2018 on dental ceramics; Rubel, Impression Materials, Dent Clin North Am 2007;51(3):629–642 (DOI 10.1016/j.cden.2007.03.006).
• No fixed-prosthodontics textbook exists in the vault — no Shillingburg, Rosenstiel or Wassell — so prep geometry has no textbook backing here beyond the lectures.