**Draft Guidance for Industry and FDA Staff**

**Class II Special Controls Guidance Document:**

**Dental Base Metal Alloys**

***Draft Guidance***

**This guidance document is being distributed for comment purposes
only.** []{.mark}

[]{.mark}

**Document issued on: \[release date of FR Notice\]**

Comments and suggestions regarding this draft document should be
submitted within **90** days of publication in the *Federal Register* of
the notice announcing the availability of the draft guidance. Submit
written comments to Dockets Management Branch (HFA-305), Food and Drug
Administration, 5630 Fishers Lane, rm. 1061, Rockville, MD 20852.
Alternatively, electronic comments may be submitted to
<http://www.fda.gov/dockets/ecomments>. All comments should be
identified with the docket number listed in the notice of availability
that publishes in the *Federal Register*.

For questions regarding this document, contact Mr. Michael E. Adjodha at
301-827-5283 or via email at mea@cdrh.fda.gov []{.mark}

**When final, this guidance will supersede "Guidance Document for the
Preparation of Premarket Notifications \[510(k)'s\] for Dental Alloys,"
issued March 3, 1997**

![](media/image1.png)

**U.S. Department Of Health and Human Services**

**Food and Drug Administration**

**Center for Devices and Radiological Health**

**Dental Devices Branch**

**Division of Anesthesiology, General Hospital,**

**Infection Control, and Dental Devices**

**Office of Device Evaluation**

**Preface**

**Additional Copies**

Additional copies are available from the Internet at:
[http://www.fda.gov/cdrh/\[+++specific](http://www.fda.gov/cdrh/%5Bspecific)
address\], or CDRH Facts-On-Demand. In order to receive this guidance
via your fax machine, call the CDRH Facts-On-Demand system at
800-899-0381 or 301-827-0111 from a touch-tone telephone. Press \"1\" to
enter the system. At the second voice prompt, press \"1\" to order a
document. Enter the document number (**1416***)* followed by the pound
sign (#). Follow the remaining voice prompts to complete your request.

**Table of Contents**

**Section Page**

1\. Background [1](#background)

2\. Scope [2](#scope)

3\. Risks to Health [3](#risks-to-health)

4\. Mechanical Properties for Casting Alloys
[3](#mechanical-properties-for-casting-alloys)

5\. Mechanical Properties for PFM Alloys
[4](#mechanical-properties-for-pfm-alloys)

6\. Biocompatibility [4](#biocompatibility)

7\. Labeling [5](#labeling)

8\. Limitations of Exemption from Premarket Notification
[5](#limitations-of-exemption-from-premarket-notification)

Draft Guidance for Industry and FDA Staff

Class II Special Controls Guidance Document: Dental Base Metal Alloys;
Guidance for Industry

***This draft guidance, when finalized, will represent the Food and Drug
Administration\'s (FDA\'s) current thinking on this topic. It does not
create or confer any rights for or on any person and does not operate to
bind FDA or the public. You can use an alternative approach if the
approach satisfies the requirements of the applicable statutes and
regulations. If you want to discuss an alternative approach, contact the
FDA staff responsible for implementing this guidance. If you cannot
identify the appropriate FDA staff, call the appropriate number listed
on the title page of this guidance.***

# Background

FDA is proposing to designate this guidance document as a special
control to exempt dental base metal alloys from premarket notification.
This guidance document is being issued in conjunction with a Federal
Register notice announcing the proposal to designate a special control.
This guidance is issued for comment purposes only. If a final rule is
not issued designating this guidance as a special control, the guidance
will not be issued.

This guidance document describes a means by which dental base metal
alloy devices may comply with the requirement of Class II Special
Controls. Designation of this guidance document as a special control
means that manufacturers of dental base metal alloy devices who follow
the recommendations listed in this document, before introducing their
device into commercial distribution in the United States, will be able
to market their device without being subject to the premarket
notification requirements of section 510(k) of the Act.

Section 510(m) of the Act provides that FDA may exempt a class II device
from the premarket notification requirements under section 510(k) of the
act if FDA determines that premarket notification is not necessary to
provide reasonable assurance of the safety and effectiveness of the
device. FDA has determined premarket notification is not necessary to
provide reasonable assurance of the safety and effectiveness of this
generic type of device if the manufacturer follows the recommendations
in this special controls guidance or equivalent measures to address the
risks identified in this guidance. Thus, persons who intend to market a
device of this type do not need to submit a premarket notification to
FDA and receive agency clearance prior to marketing the device, but as a
class II device, the device must comply with the general and special
controls (Section 513(a)(1)(B)).

Following the effective date of a final rule exempting the device,
manufacturers of dental base metal alloy devices will need to address
the issues covered in this special control guidance. However, the
manufacturer need only show that its device meets the recommendations of
the guidance or in some other way provides equivalent assurances of
safety and effectiveness.[^1] If manufacturers cannot comply with these
recommendations or equivalent measures, they will not be exempt from the
requirements of premarket notification and will need to submit a
premarket notification and receive clearance for their device prior to
marketing.

FDA\'s guidance documents, including this guidance, do not establish
legally enforceable responsibilities. Instead, guidances describe the
Agency\'s current thinking on a topic and should be viewed only as
recommendations, unless specific regulatory or statutory requirements
are cited. The use of the word *should* in Agency guidances means that
something is suggested or recommended, but not required.

# Scope

FDA identifies a dental base metal alloy as a device, classified under
21 CFR §872.3710 below:

> Sec. 872.3710 Base metal alloy.
>
> \(a\) Identification. A base metal alloy is a device composed of a
> material, such as a mixture of nickel and chromium, intended for use
> in fabrication of a custom-made dental device, such as porcelain
> veneer for a tooth.
>
> \(b\) Classification. Class II.

A base metal alloy may be primarily composed of chromium, cobalt, and
nickel, with lesser amounts of other elements such as molybdenum and
aluminum. The device is intended to fabricate:

-   all-metal (cast) dental appliances such as crowns and bridges; or

-   the coping or substrate to which is fused a ceramic coating for
    fabricating dental appliances such as crowns and bridges.

This classification includes cast and porcelain-fused-to-metal (PFM),
cobalt-chromium, and nickel-chromium alloys and solders. The product
code associated with this classification identification is EJH - Metal,
Base.

The scope of this guidance does not include precious metal alloys, which
is addressed in the draft guidance entitled, **Class II Special Controls
Guidance Document: Precious Metal Alloys**,
[[http://www.fda.gov/cdrh/ode/guidance/1415.pdf]{.underline}](http://www.fda.gov/cdrh/%5Bspecific),
also issued for comment at this time. This guidance also does not
include any mercury (Hg) amalgam alloys or dental Hg, which are
classified in 21 CFR 872.3050 and 21 CFR 872.3700, respectively.

# Risks to Health

FDA has identified the following risks to health associated with the use
of the dental base metal alloy in the tables below, depending on whether
the device is a casting metal alloy or a PFM alloy. FDA recommends the
following measures to mitigate the identified risks in this guidance, as
shown in the tables below.

**Casting Alloys**

  --------------------------- -------------------------------------------
  **Identified Risks**        **Recommended Mitigation Measures**

  Device failure              Section 4. Mechanical Properties for
                              Casting Alloys

  Adverse tissue reaction     Section 6. Biocompatibility

  Improper use                Section 7. Labeling
  --------------------------- -------------------------------------------

**PFM Alloys**

  --------------------------- -------------------------------------------
  **Identified Risks**        **Recommended Mitigation Measures**

  Device failure              Section 5. Mechanical Properties for PFM
                              Alloys

  Adverse tissue reaction     Section 6. Biocompatibility

  Improper use                Section 7. Labeling
  --------------------------- -------------------------------------------

The mechanical properties of the device may be insufficient to support
the required loads and lead to device failure. Porcelain may deform,
crack, and debond from the metal because of incompatibilities. Some
alloy compositions may also be susceptible to corrosion. These device
failures may result in ineffective treatment, revision, and possibly
minor, temporary impairment for the patient.

Some alloy compositions, especially those containing nickel, may not be
biocompatible. Poor biocompatibility may result in adverse tissue
reaction.

Inadequate labeling may result in improper use. Improper use may result
in ineffective treatment and may cause minor, temporary impairment for
the patient.

# Mechanical Properties for Casting Alloys

We recommend that base metal casting alloys conform to the FDA-
recognized standard below.

-   **American National Standard/American Dental Association
    Specification No. 14-1998, \"Dental Base Metal Casting Alloys\"**
    (ANSI/ADA Specification No. 14)

In particular, Table 1 of the ANSI/ADA Specification No. 14 specifies
the minimum mechanical properties for casting alloys. Section 3.1 of
this standard specifies compositions resistant to corrosion. Section
3.2.1.1 of this standard specifies that no visible signs of corrosion
should be seen for one year when exposed to an oral environment.

For base metal solders (brazing alloys), we recommend conformance to the
FDA- recognized standard below.

-   **American National Standard/American Dental Association
    Specification No. 88-2000, \"Dental Brazing Alloys\"** (ANSI/ADA
    Specification No. 88)

In particular, section 4.5 of ANSI/ADA Specification No. 88 specifies
the minimum mechanical properties for solders.

# Mechanical Properties for PFM Alloys

We recommend that base metal PFM alloys conform to the FDA-recognized
standard below.

-   **American National Standard/American Dental Association
    Specification No. 38-2000, \"Metal-Ceramic Dental Restorative
    Systems\"** (ANSI/ADA Specification No. 38)

In particular, Table 1 of the ANSI/ADA Specification No. 38 specifies
the minimum mechanical properties of the metal. Table 2 of this standard
specifies the minimum mechanical properties of the porcelain for these
metals. Section 4.3.3 of this standard specifies the minimum bond
compatibility index between the metal and porcelain.

# Biocompatibility

We recommend that you insure the biocompatibility of your device by
complying with the tests in the following standard for a permanent
contact, external communicating device on tissue, bone, or dentin in
accordance with the applicable requirements of ISO-10993 (instead of
ANSI/ADA Specification No. 41, which is incorporated by reference in
ANSI/ADA Specification No. 14). See Blue Book Memorandum #G95-1,
entitled \"Use of International Standard ISO-10993, Biological
Evaluation of Medical Devices Part 1: Evaluation and Testing,\"
<http://www.fda.gov/cdrh/g951.html>, for additional guidance on the use
of ISO-10993.

# Labeling

As a prescription device, under [21 CFR
801.109](http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?FR=801.109),
the device is exempt from having adequate directions for lay use.[^2] We
recommend that your labeling include a contraindication for nickel
hypersensitive individuals, if the alloy composition contains \>1% Ni.

# Limitations of Exemption from Premarket Notification

FDA\'s decision to exempt a Class II device from the requirement of
premarket notification is based on the existing and reasonably
foreseeable characteristics of devices within that generic type that
currently are, or have been, in commercial distribution. Section 21 CFR
872.9 specifies the limitations to exemption. If any of these
limitations apply, your device is not exempt and you must submit a
premarket notification.

[^1]: We recommend that you document how you have addressed the
    recommendations in your design history file. Manufacturers must
    maintain design controls, including a design history file, in
    accordance with 21 CFR 820.30.

[^2]: Final labeling must comply with the requirements of 21 CFR 801
    before a medical device is introduced into interstate commerce.