What is a porcelain-fused-to-metal crown? How is it different from an all-ceramic crown? Start with whether there is a metal layer

What is a porcelain-fused-to-metal crown? How is it different from an all-ceramic crown? Start with whether there is a metal layer

Direct answer in 60 words

Direct answer: “Porcelain tooth” generally means a porcelain-fused-to-metal crown (PFM): metal on the inside and porcelain fused on the outside. An all-ceramic crown has no metal inner layer. To confirm which one you have, check the item name on the fee document.[F4][F5][F6]

Geographic scope: This guide is specific to Taiwan's healthcare system (National Health Insurance and Taiwan's Medical Care Act). Its institutional passages on approved fees, benefit coverage, and disclosure duties apply only in Taiwan. Its clinical-evidence passages cite international literature and report results at the study-population level; they cannot estimate any individual's treatment outcome.[F2]

Match the names first: what is the term you heard called in the document?

People who search for “烤瓷牙” have usually heard a term in the dental office or on a quotation and want to check, at home, what it is and whether it is the same thing that others call an “all-ceramic crown.”

First, one point that saves a lot of effort: “烤瓷牙” is a colloquial term with no official definition. Different sources use their own naming systems. Rather than define a colloquial term, this card shows how to cross-reference three naming systems that actually exist.[F2]

• Taiwan fee-item name: Under “prosthodontics,” the Taipei City Department of Health's approved dental-fee schedule lists item 2-29 as “金屬瓷冠(PFM-陶瓷熔附金屬全冠)” (metal ceramic crown / PFM), charged per tooth.[F5] Item 2-30 is the separate item “全瓷牙冠” (all-ceramic crown), also per tooth.[F6] They are two different items in the approved document.
• International literature and indexing vocabulary: The U.S. National Library of Medicine's MeSH includes Metal Ceramic Alloys (vocabulary code D016876), defined as porcelain fused to an alloy of two or more metals for restorative and prosthodontic dentistry. It gives cobalt-chromium, gold-palladium, gold-platinum-palladium, and nickel-based alloys as examples (the source says examples: not an exhaustive list and not a frequency ranking). Its synonyms also include Porcelain-Metal Alloys and Metal Ceramic Restorations.[F4]
• The same fee schedule has other crowns: Item 2-27 “鑄造冠” (cast crown), item 2-28 “鑲面鑄造冠” (faced cast crown), and item 2-31 “治療性暫時冠” (therapeutic temporary crown) are each separate, all per tooth.[F7] In the document, “is mine metal or porcelain?” therefore has more than two options.

Keep these three naming systems separate; do not substitute one for another: fee-item names are administrative categories, MeSH is controlled vocabulary for literature indexing, and “烤瓷牙” is colloquial. This card does not claim that their scopes are identical.[F2] The short practical step is: see which item name is written on the quotation or treatment plan. That is what you can confirm with the dentist and compare with the fee schedule.[F5][F6][F20]

Before comparing them: an easy way to misread the evidence

When these material categories are compared online, a common move is to subtract one survival figure from article A from another survival figure in article B and then say there is a difference of some number of percentage points.

That subtraction usually does not hold. Studies can differ in follow-up duration, tooth site (anterior or posterior), prosthesis form (single crown or bridge), and what counts as “failure.” Some count a crown that remains in the mouth as surviving; some require that there has been no complication at all to call it successful. Subtracting figures with different definitions produces noise, not a difference.[F2]

This card therefore gives priority in its first two dimensions to evidence that compares both materials within the same study. Where findings from different studies must be presented together, it states that they come from different studies and cannot be directly subtracted.[F2]

Dimension one: how long can it last? Start with a direct comparison within one trial

A randomized controlled clinical study published in 2017 followed two single-crown groups in the same study for 5 years. Its conditions were specific: 72 patients and 90 single crowns, all on endodontically treated posterior teeth with no periapical lesion or active periodontitis (molars or premolars). One group used zirconia as the framework and the other metal; both groups had pressable veneering ceramic on the outside.[F9]

At 5 years, the authors concluded that single-crown survival was similar in the two groups, with no significant differences in esthetic, functional, or biological outcomes.[F9] During follow-up, veneering-ceramic chipping was found in 2 metal-ceramic crowns and 3 zirconia-based crowns. One zirconia-group crown had a core fracture (the source term; the abstract does not define it further), and one metal-ceramic crown was lost because of root fracture.[F9]

State how much this evidence can carry as well: it was a single-centre trial of 90 crowns, restricted to endodontically treated posterior teeth, and its zirconia comparator was veneered (an additional fired porcelain layer), not a monolithic all-ceramic crown.[F9] It answers, “when both have a veneer, what differs over 5 years when the framework is metal rather than zirconia?” It cannot answer whether a monolithic all-ceramic crown is better than a PFM crown.

For a population-level estimate across studies, a 2026 systematic review and meta-analysis concluded that lithium-disilicate and zirconia-based all-ceramic single crowns can achieve five-year survival rates comparable to metal-ceramic single crowns.[F8] The complete material-specific figures, confidence intervals, and how to read them belong to the crown-cost card and are not repeated here; see the internal citation chain.[F2]

Dimension two: chipping is not exclusive to either side, but the monolithic route exists only within all-ceramic crowns

The trial above also has a conclusion that is easy to overlook: the shared main failure mode in both groups was chipping of the veneering ceramic.[F9] Thus, neither “PFM crowns chip but all-ceramic crowns do not” nor “all-ceramic crowns chip but PFM crowns do not” is supported by that direct comparison.

The actual dividing line is elsewhere. The same 2026 meta-analysis reported significantly fewer ceramic fractures and chips in monolithic lithium-disilicate and monolithic zirconia crowns than in veneered alternatives.[F8] The limit matters: the abstract does not list which categories are included in “veneered alternatives,” so this card does not specify them for it.[F8]

One thing does follow from the definition: a PFM, by definition, has porcelain fused to metal.[F4] It therefore necessarily has a veneer layer. The option of changing to monolithic design (no veneer layer) to reduce chipping risk exists within the all-ceramic branch, but not the PFM branch. That is a structural difference, not a verdict that one is better, and not advice for your tooth.[F2] One further limit: crowns all called metal ceramic can differ in occlusal-surface design; the approved fee document expressly lists different occlusal-surface design as a source of variation for that item.[F5] This search did not find citable comparative evidence for the actual effect of those design differences on chipping. The card therefore does not describe an effect and lists it only as a question to ask in the dental office.[F3] The trade-offs of monolithic design itself (translucency, antagonist-tooth wear, and duration of long-term data) belong to the two all-ceramic-crown cards and are not repeated here.[F2]

Dimension three: metal allergy—a question to ask only when there is a metal layer

Where there is a metal layer, there is a question of what that layer is. MeSH gives cobalt-chromium, gold-palladium, gold-platinum-palladium, and nickel-based alloys as examples for this material class (the original says examples, not a complete list).[F4] That also means that the inner metal can differ substantially among crowns all called metal ceramic.

What the literature currently says is:

• It is rare overall. A multicentre retrospective analysis published in 2024 selected 2,730 eligible people from 169,834 people patch-tested from 2005 through 2019. The authors state directly that allergic contact stomatitis to dental materials is rare.[F12]
• But metals were prominent among the people with confirmed disease. In the same study, among women with confirmed allergic contact stomatitis (444 people), the higher sensitization rates were for metals: nickel 28.6%, palladium 21.4%, and amalgam 10.9%.[F12] Read that denominator carefully: it is people who were patch-tested because contact allergy was suspected and who were then confirmed, not the general public and not the incidence among people who received a PFM crown.[F12]
• For cobalt-chromium: a 2022 review (whose authors selected 21 studies from 836 under PRISMA methodology) reported that, in in-vivo studies, Co-Cr could rarely cause sensitization, irritation, and allergic reactions; reactions were mainly observed in people already allergic to Co or Cr.[F13] The review also includes in-vitro comparisons between materials. Those are material-selection information for clinicians, so this card does not put them in the reader-facing text, where they could be read as an implication to change material; the source statement remains in the fact ledger for traceability.[F13][F2]
• One kind of study cannot answer this question. A 2026 toxicology study immersed Co-Cr specimens in artificial saliva for six months, then measured released ions and assessed toxicity in human fibroblast cells and 20 male mice.[F14] Those are in-vitro and animal-level findings. They cannot be extrapolated to risk for people with an intraoral restoration, and this card makes no clinical conclusion from them.[F14][F3]

So this section gives not an answer but a sentence worth saying: if you have a history of metal allergy, especially to nickel, cobalt, or chromium, tell the dental team before treatment. Article 81 of Taiwan's Medical Care Act requires medical institutions to inform patients of the condition, treatment course, disposition, medication, expected condition, and possible ill effects; within that framework, you can ask what category the inner alloy belongs to.[F21] Whether patch testing is needed or another material should be used is a clinical judgment for the dentist, with dermatology input when needed. This card does not offer material-selection advice.[F2]

Dimension four: the grey-looking line at the gingival margin

“The gingiva at the edge of my crown looks grey-blue” is a common question about this material category. There is a corresponding record in the literature, but the evidence level must be stated first.

A clinical study published in 2019 involved 25 people referred for cast dowel and PFM restorations, made from nickel-chromium alloys. At 90 days after cementation, 61 abutment teeth were divided into a group with gingival discoloration (25 teeth) and one without it (36 teeth).[F15] The article also states that this grey-blue gingival discoloration may occur not only near amalgam restorations but also in teeth restored with cast dowels and PFMs.[F15] Its conclusion was that impairment of periodontal status of the abutment teeth seemed to be related to the presence of gingival discoloration.[F15]

Here is an easy error to stop before it happens: 25 of 61 cannot be read as “four to ten percent of PFM crowns become discoloured.” These are group counts from one centre and referred patients, with cast dowels present and only 90 days of observation. The source did not report them as an incidence, and this card does not calculate one.[F15][F3]

Gingival response is not only about material; it also relates to where the margin is placed. A review commissioned for the 2017 World Workshop stated that margins placed within the junctional epithelium and supracrestal connective tissue attachment can be associated with gingival inflammation and potentially recession. A margin within the gingival sulcus, by contrast, does not cause gingivitis if the patient follows self-performed plaque control and periodic maintenance.[F16] A 2022 narrative review (lower evidence level than a systematic review) describes a consequence chain for a discrepant margin: enhanced dental-biofilm accumulation, microleakage, hypersensitivity, margin discoloration, increased gingival-crevicular-fluid flow, recurrent caries, pulp infection, and finally periodontal lesion and bone loss.[F17]

This card cannot remotely attribute your line to metal, margin location, gingival recession, or recurrent caries. A dentist needs to examine it. Color and margin concerns on the all-ceramic side belong to a different card; see the internal citation chain.[F2]

Dimension five: can I have MRI after receiving a PFM crown?

Start with the action to take: when arranging head-and-neck imaging, tell the imaging and dental teams that you have a metal restoration in your mouth so they can assess it.[F19] You do not need to decide anything yourself.

Two evidence points need to be presented together:

• A 2022 systematic review (19 included from 151 full texts) reported that artifacts caused by orthodontic appliances were well documented, with stainless-steel brackets most likely to cause artifacts in head-and-neck MR imaging. But the literature on implants and prosthodontic restorations was scarce; for that part, the review found the data inconclusive. Artifact severity depends on material features, oral location, and magnetic-resonance parameters.[F18]
• A 2026 narrative review, not a systematic review, states that dental consultation is necessary before any head-and-neck MRI to avoid unintended effects of dental restorations, such as artifacts in the area of interest or radiofrequency-induced heating of the material.[F19]

These are not contradictory, but they are at different evidence levels: the first is a systematic review that explicitly says evidence for prosthodontic restorations is insufficient; the second is a narrative review that provides a workflow recommendation to clinical and imaging teams.[F18][F19] This card does not tell you that anything should or should not be removed or replaced. That is a clinical judgment; your action remains to disclose the restoration.[F2]

Dimension six: costs both options share

Some things do not disappear because one material rather than another is selected. This section is meant to keep attention from resting entirely on “metal or all ceramic”:

• Prepared tooth structure does not grow back. A 2026 systematic review including 23 studies states in its research aim that crown preparation leads to irreversible dental tissue loss and affects long-term restoration success.[F11] This applies to both crown categories.
• The opposing natural tooth can wear. A 2024 systematic review and network meta-analysis (7 clinical studies, 261 crowns, 177 subjects, through 24 months after permanent crown placement) found that metal ceramic and zirconia caused significantly higher antagonist-enamel wear: 82.5 µm (54.4 to 110.6) and 40.1 µm (22.2 to 58.0), respectively, more than the natural-teeth group. Lithium disilicate showed only 5.0 µm more, with an interval of −48.2 to 58.1 that crosses 0 and therefore does not exclude no difference.[F10] The literature has not converged on this question: another 2026 meta-analysis ranked materials differently. The side-by-side account of three studies and how to read it belong to the all-ceramic-regret card.[F10][F2]
• Teeth under and at the margin of a crown can still decay. Maintenance and follow-up are part of this choice.[F16][F17]

Fees: this card gives no amount, only two usable points

First, the institutional point: there is no single nationwide price. Article 21 of Taiwan's Medical Care Act states that standards for medical fees charged by medical care institutions are determined by the municipal or county(city) competent authority.[F20] To check, return to the approved fee schedule for the city or county where you receive care.

Second, the document itself states what the differences can come from, which makes useful questions for the dental office:

• Item 2-29, metal ceramic crown (PFM), says in announcement-content item 5: “依鑄造用金屬不同及咬合面設計不同而有所差異。” and in item 6: “超重金屬費用另計。”[F5]
• Item 2-30, all-ceramic crown, says in announcement-content item 5: “依使用全瓷材料及製作方式不同而有所差異。”[F6]
• Read together, these say that the variables for one branch are the casting-metal type and occlusal-surface design, with an additional statement that “超重金屬費用另計。” The official meaning of that phrase was not obtained, so it is quoted but not translated. For the other branch, the variables are all-ceramic material and fabrication method, with no metal-related additional-charge clause.[F5][F6] This is a structural difference in the official document, not price advice and not a statement that either side is more or less expensive.[F2]

Two other points are often confused:

• Crowns are on the self-pay side. Subparagraph 11, Article 51 of Taiwan's National Health Insurance Act lists “Dentures, artificial eyes, spectacles, hearing aids, wheelchairs, canes, and other treatment equipment not required for positive therapy” among items outside benefit coverage.[F23] Whether another procedure in the same course of care is covered follows current notices of Taiwan's National Health Insurance Administration.
• The National Health Insurance Administration's medical-device comparison website cannot be used to look up dentistry: its item categories in both search paths contain no dentistry, so crowns, dentures, and implants cannot be found there. Do not use it as a route to verify dental fees.[F24] The route for dental fees is fee standards approved by each municipal or county health authority[F20][F5] plus the institution's written quotation.

How to break down a quotation line by line, and what to inspect when two quotations differ markedly, belong to the crown-cost and all-ceramic-crown-price cards. This card gives no monetary amount.[F2]

Risk factors (what to know before treatment)

Any crown requires removal of some tooth structure that cannot be restored. It is a treatment with medical risks; indications and contraindications must be assessed by a dentist for the individual's situation:

• Irreversible dental-tissue loss: crown preparation causes tooth-structure loss that cannot be restored and affects long-term restoration success.[F11]
• Veneering-ceramic chipping: in the 5-year randomized controlled trial, the shared main failure mode in both groups—metal and zirconia frameworks, both with veneer ceramic—was chipping of the veneer ceramic.[F9]
• Framework/core or root fracture: the same trial recorded 1 core fracture in the zirconia group (the source term; the abstract does not define it further) and 1 metal-ceramic crown lost for root fracture.[F9]
• Metal-related reactions: allergic contact stomatitis to dental materials is rare, but sensitization rates were higher for metals (nickel, palladium, and amalgam) in the confirmed population.[F12] Co-Cr rarely caused sensitization in in-vivo studies, and reactions were mainly in people already allergic to Co or Cr.[F13] If you have a history of metal allergy, disclose it before treatment.
• Gingival response and discoloration: grey-blue gingival discoloration has been observed around cast dowels and PFM restorations made from nickel-chromium alloys.[F15] Margin location and cleaning/maintenance affect gingival response,[F16] and a discrepant margin is associated with consequences including biofilm accumulation, recurrent caries, and periodontal lesion.[F17]
• Imaging: dental materials can cause artifacts in MRI, but literature on prosthodontic restorations is scarce and its conclusion is inconclusive; severity depends on material, location, and magnetic-resonance parameters.[F18] When arranging head-and-neck imaging, disclose the restoration.[F19]
• How much weight these figures can carry: all proportions, event counts, and intervals in this card come from observations in specified study populations during specified follow-up periods. Eligibility criteria, follow-up duration, and failure definitions differ. Using them to predict your tooth would overextend them. Actual treatment methods and outcomes vary by person and require a dentist's assessment.

Pre-visit checklist: seven questions you can ask when a crown is recommended

1. Which item name is written on my treatment plan—metal ceramic crown (PFM), all-ceramic crown, cast crown, or faced cast crown?[F5][F6][F7]
2. If it is a metal ceramic crown, what category is the inner alloy (for example cobalt-chromium, gold-palladium, gold-platinum-palladium, or nickel-based)?[F4]
3. Do I have any history of metal allergy I should mention first? Could it affect material selection?[F12][F13]
4. How is the occlusal surface of this crown designed? The approved document lists occlusal-surface design as a source of variation. How was it decided in my plan?[F5]
5. Where will the crown margin be placed (supragingival, at the gingival level, or subgingival)? Why there, and how should I clean it?[F16][F17]
6. Is the opposing tooth a natural tooth or a denture/tooth replacement? How will the bite be adjusted, and how often should I return to have the occlusal surface checked?[F10]
7. Please explain this treatment plan's risks, prognosis, and possible adverse reactions once. This is within the disclosure scope of Article 81 of Taiwan's Medical Care Act.[F21] Compare fees with the approved schedule in the city or county where you receive care and with the institution's written quotation.[F20]

Every clinical statement in this article is mapped line by line to its cited source (see the sources and evidence chain below). It has not been clinically reviewed by a licensed practitioner. This is health information, not individual advice; assessment by a clinician is required.