D6740 vs D2740: When to Use Each Porcelain Crown CDT Code

Understanding Crown CDT Codes

Crown procedures are among the highest-revenue services in restorative dentistry, and correct CDT code selection directly impacts reimbursement. The CDT code set includes two distinct categories of crown codes: single crown codes in the D2700 series (restorative) and retainer crown codes in the D6700 series (prosthodontics, fixed). Confusing these two categories is one of the most costly billing errors a dental practice can make.

The fundamental distinction is straightforward: D2700-series codes are for standalone crowns placed on individual teeth, while D6700-series codes are for crowns that serve as abutment retainers for fixed bridges. Even though the clinical crown preparation and cementation technique may be identical, the purpose of the crown determines the correct code category. For a broader look at all CDT code categories, see our complete CDT codes guide.

Getting the category wrong does not just cause a denial — it can invalidate the entire bridge claim. Insurance carriers process bridge claims as a unit, and submitting a single crown code for an abutment tooth tells the carrier that the tooth received a standalone restoration, not a bridge retainer. This mismatch triggers denial of both the retainer and the pontic codes.

What Is CDT Code D2740?

CDT code D2740 is defined as “crown — porcelain/ceramic substrate.” This code is used for a full-coverage crown fabricated entirely from porcelain or ceramic material (such as lithium disilicate, zirconia, or feldspathic porcelain) that is placed on a single tooth as a standalone restoration.

D2740 is the most commonly billed crown code in modern dentistry, reflecting the industry-wide shift toward all-ceramic restorations for their superior aesthetics and biocompatibility. Clinical indications for D2740 include teeth with extensive decay that cannot be adequately restored with a direct restoration, fractured teeth requiring full coverage, endodontically treated teeth needing cuspal protection, and teeth with significant structural compromise from large existing restorations.

The key billing qualifier for D2740 is that the crown must be a standalone restoration on a single tooth. The moment that crown also serves as an abutment for a fixed bridge, it must be coded under the D6700 retainer crown series instead. The material composition (all-ceramic) is the same, but the function determines the code.

What Is CDT Code D6740?

CDT code D6740 is defined as “retainer crown — porcelain/ceramic.” This code is used for a full-coverage porcelain or ceramic crown that functions as an abutment retainer for a fixed bridge (fixed partial denture). The crown is not a standalone restoration — it is one component of a multi-unit bridge prosthesis.

When billing a three-unit porcelain bridge, for example, the claim would include two D6740 codes (one for each abutment retainer crown) and one D6245 code (pontic, porcelain/ceramic) for the replacement tooth spanning the edentulous space. Each component of the bridge is billed separately but processed as a single prosthetic case by the insurance carrier.

D6740 follows the same material classification as D2740 — both describe all-ceramic or all-porcelain restorations. The clinical preparation, impression technique, and cementation protocol are identical. The only difference in the CDT code selection is the functional role of the crown: standalone (D2740) versus bridge abutment (D6740).

The Critical Difference: D2740 vs D6740

The distinction between D2740 and D6740 comes down to a single question: is the crown a standalone restoration, or is it an abutment for a fixed bridge? Getting this wrong is a surprisingly common billing error that results in predictable and preventable denials.

• D2740 (Single Crown): Use when placing a porcelain crown on a single tooth that is not connected to any other prosthetic unit. The crown restores only that individual tooth and has no connection to adjacent restorations.
• D6740 (Bridge Retainer): Use when placing a porcelain crown on a tooth that serves as an abutment for a fixed bridge. This crown is connected to a pontic (replacement tooth) and is part of a multi-unit prosthesis. It must always be billed alongside the appropriate pontic code(s).

A practical example illustrates the distinction. If tooth #19 is missing and the dentist places a three-unit bridge from tooth #18 to tooth #20, the correct billing is: D6740 on tooth #18 (retainer crown), D6245 on tooth #19 (pontic), and D6740 on tooth #20 (retainer crown). Billing D2740 on teeth #18 and #20 would result in a denial because single crown codes do not support a bridge prosthetic and the pontic code has no associated retainers.

Another common scenario is when a patient needs a single crown on one tooth and a bridge involving adjacent teeth. In this case, the standalone crown receives a D2740 code and the bridge abutments receive D6740 codes. Both code types can appear on the same claim for the same patient as long as they apply to different teeth with different clinical indications.

Other Crown Codes You Should Know

Beyond D2740 and D6740, the CDT code set includes several other crown codes that vary by material composition. Selecting the correct material-based code is essential because insurance carriers reimburse at different rates for different materials and may apply downcoding policies based on tooth location and material selection.

• D2750 — Crown, Porcelain Fused to High Noble Metal: A porcelain-fused-to-metal (PFM) crown with a high noble metal substructure (containing at least 60% noble metal, of which at least 40% is gold). This is the traditional PFM crown and remains widely used for posterior restorations.
• D2751 — Crown, Porcelain Fused to Predominantly Base Metal: A PFM crown with a predominantly base metal substructure (containing less than 25% noble metal). This is the least expensive PFM option and the code most insurance carriers use as their downcoding baseline for posterior crowns.
• D2752 — Crown, Porcelain Fused to Noble Metal: A PFM crown with a noble metal substructure (containing at least 25% noble metal but not meeting high noble metal criteria). This falls between D2750 and D2751 in both cost and reimbursement.
• D2799 — Provisional Crown: A temporary or interim crown, typically fabricated chairside from acrylic or composite material. This code is used for longer-term provisional restorations, not for the temporary crown placed between preparation and final cementation (which is included in the final crown code).

Each of these single crown codes has a corresponding retainer crown code in the D6700 series. For example, D6750 is the retainer crown equivalent of D2750 (PFM, high noble), and D6751 corresponds to D2751 (PFM, predominantly base metal). The material classification is identical; only the functional role (single vs retainer) differs.

Insurance Coverage for Crowns

Crown procedures are classified as “major services” by most dental insurance carriers and are typically covered at 50% after deductible. This lower coverage percentage, combined with significant crown fees, means patients face substantial out-of-pocket costs. Understanding coverage rules helps practices communicate costs accurately and avoid surprise balance situations.

• Coverage Percentage: Most PPO plans cover crowns at 50% after the annual deductible. Some premium plans cover at 60% or even 80%, but these are the exception. Waiting periods of 6 to 12 months are common on major services, meaning new plan members may have no crown coverage during their first year.
• Frequency Limitations: Insurance plans typically allow one crown per tooth every 5 to 10 years. The frequency clock starts on the date of service (seat date) for the original crown. If a crown fails within the frequency window, the replacement may not be covered unless specific medical necessity criteria are met.
• Material Downgrades: Many carriers apply an alternate benefit clause that reimburses all crowns at the lowest-cost material alternative, regardless of what was actually placed. A D2740 all-ceramic crown may be reimbursed at the D2751 (PFM base metal) fee, with the patient responsible for the fee difference.
• Bridge Coverage: Fixed bridges (including D6740 retainer crowns) are covered under prosthodontic benefits, which may have different coverage levels, deductibles, and frequency limitations than single crown benefits. Some plans have a separate prosthodontic maximum.

A critical coverage detail: many insurance plans apply a “missing tooth clause” that excludes coverage for bridges if the tooth being replaced was already missing when the patient’s coverage began. This clause does not affect single crown coverage (D2740) but frequently impacts bridge claims (D6740/pontic codes). Verify missing tooth clause applicability during eligibility verification.

Pre-Authorization Requirements

Most insurance carriers require pre-authorization (also called pre-determination or prior authorization) for crown and bridge procedures. Submitting a thorough pre-authorization package increases the likelihood of approval and gives your practice and the patient clarity on coverage before the procedure begins.

• What to Include: A complete pre-authorization submission should include the proposed CDT code(s), tooth number(s), a current periapical or bitewing radiograph showing the tooth requiring the crown, and a clinical narrative explaining the medical necessity.
• Narrative Content: The narrative should describe the existing condition of the tooth (extent of decay, fracture lines, existing restoration size), why a less extensive restoration is not adequate, and the material being recommended. For bridges, include the reason the missing tooth cannot be restored with an alternative prosthetic.
• Processing Time: Pre-authorization responses typically take 2 to 4 weeks. Some carriers offer electronic pre-authorization with faster turnaround. Schedule the crown preparation appointment after receiving the pre-authorization response so you can discuss the exact patient cost.
• Pre-Auth vs Guarantee:A pre-authorization is not a guarantee of payment. It is an estimate of benefits based on the information provided and the patient’s eligibility at the time of the request. If the patient’s coverage changes between pre-authorization and the date of service, the claim may be denied.

For bridge cases, submit the pre-authorization for all components of the bridge together (both retainer crowns and the pontic). Submitting individual components separately can result in partial approvals that do not reflect the actual treatment plan.

Common Crown Billing Errors

Crown claims have a high denial rate compared to other restorative procedures, largely because of preventable billing errors. Here are the mistakes we encounter most frequently. For a broader view of denial prevention, see our guide to reducing claim denials.

Documentation Requirements

Thorough documentation is essential for crown claims to withstand insurance review and potential audits. The documentation must establish medical necessity and justify the specific crown type selected. Here is what every crown chart entry should include:

• Clinical Justification:Description of the tooth condition requiring a crown — extent of caries (percentage of tooth structure compromised), fracture type and location, existing restoration failure with specifics, or endodontic treatment requiring cuspal coverage
• Radiographic Evidence: A current periapical or bitewing radiograph showing the tooth condition. The image should demonstrate the extent of decay, periapical pathology (for endodontic cases), or the relationship between the existing restoration and remaining tooth structure
• Clinical Photographs: Intraoral photographs showing the clinical presentation before preparation are increasingly requested by carriers. Photographs are particularly valuable for documenting fracture lines, staining, and existing restoration conditions that may not be visible on radiographs
• Material Selection Rationale: If using a premium material (such as full-contour zirconia or high-translucency lithium disilicate), note the clinical reason for the material choice. Carriers that apply alternate benefit downcoding may accept the higher-cost material if the clinical narrative supports it
• Alternative Treatment Considered: Note why a less invasive restoration (such as an inlay, onlay, or large direct restoration) was not appropriate. This demonstrates that the crown was the least invasive adequate treatment option

For bridge cases, the documentation must also include the reason for the missing tooth, the condition of the abutment teeth, and why a fixed bridge was selected over alternative replacement options such as a removable partial denture or implant.

Insurance Downcoding on Crown Claims

Downcoding is one of the most frustrating aspects of crown billing. Insurance carriers routinely apply alternate benefit provisions that reimburse an all-ceramic crown (D2740) at the rate of a lower-cost alternative, such as PFM base metal (D2751) or even an amalgam restoration. Understanding how downcoding works helps your practice manage patient expectations and decide when to appeal. For more on denial and downcoding appeals, see our dental claim denials guide.

• Material Downcoding:The most common form. A carrier pays for D2740 at the D2751 allowable fee, leaving the patient responsible for the difference between what the carrier pays and the practice’s fee. In-network providers must accept the contracted fee and absorb the difference.
• Crown-to-Restoration Downcoding: Some carriers downcode crowns on posterior teeth to a large direct restoration code (D2393 or D2394), particularly when the clinical documentation does not demonstrate why a direct restoration would be inadequate. This results in significant reimbursement reduction.
• When to Appeal: Appeal downcoding when you have strong clinical documentation, radiographic evidence, and photographs that demonstrate the medical necessity for the specific crown placed. Appeals are most successful when the documentation clearly shows that a less extensive restoration would not provide adequate treatment.

To minimize the impact of downcoding, inform patients during treatment presentation that their insurance may apply an alternate benefit provision. Provide a written estimate showing the potential patient responsibility under both the submitted code and the likely downcoded code so patients are not surprised by their balance.

Related Codes: Core Build-Ups, Posts, and Temporaries

Crown procedures frequently involve additional services that require separate CDT codes. Understanding which related codes can and cannot be billed alongside crown codes prevents both underbilling and overbilling.

• D2950 — Core Buildup: Billed when a core buildup is placed to replace missing tooth structure before the crown preparation. The buildup must be a separate procedure from the crown preparation itself. Some carriers bundle D2950 into the crown fee and will not reimburse it separately. Others require documentation showing that the remaining tooth structure was insufficient to retain a crown without a buildup.
• D2954 — Prefabricated Post and Core: Used when a prefabricated post is placed into a root canal-treated tooth to provide retention for the core buildup. This code includes both the post and the core material. Document the post type, size, and the canal it was placed into.
• D2799 — Provisional Crown: The temporary crown placed between preparation and final cementation is considered part of the crown procedure and is not billed separately. D2799 is reserved for longer-term provisional restorations intended to remain in place for an extended period (such as during implant healing or extensive treatment planning phases).

A common revenue loss occurs when offices do not bill D2950 when a core buildup was legitimately performed. If more than half of the coronal tooth structure is missing and a core buildup was placed, it should be billed separately. Conversely, billing D2950 when minimal tooth structure was replaced (essentially just “fill and prep”) is considered overbilling and can trigger audits.

How Dental Billing Assist Maximizes Crown Reimbursement

At Dental Billing Assist, we treat crown claims as high-value billing opportunities that require meticulous attention to detail. Our team’s experience with crown coding ensures your practice captures maximum reimbursement while maintaining full compliance.

• Code Verification: We verify every crown claim uses the correct code category (D2700 vs D6700) and material classification before submission, eliminating category mismatch denials
• Pre-Authorization Management: We prepare and submit complete pre-authorization packages including clinical narratives, radiographs, and photographs, and track authorization status through to approval
• Downcoding Appeals: When carriers downcode crown claims, we file detailed appeals with supporting documentation to recover the full reimbursement your practice is entitled to
• Ancillary Code Capture: We ensure that related services like core buildups (D2950) and posts (D2954) are billed when clinically appropriate, preventing revenue leakage on procedures your practice legitimately performed

Crown procedures represent a significant portion of most practices’ revenue. Our systematic approach to crown billing ensures that every dollar your practice earns is captured through accurate coding, proactive pre-authorization, and aggressive denial management.