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One thing we know for certain in this digital workflow world is that things change. Among the most significant changes recently for dental laboratories were the releases of new 510(k) clearances by the suppliers of titanium base abutments (Ti bases) and pre-milled blanks. With these new options, what is best for you?
Determining the best option for bringing custom implant abutment manufacturing in-house requires an understanding of what each involves. The present information available and disseminated may not be accurate and consistent with the requirements of the US Food and Drug Administration (FDA).
The basic FDA requirement is that all digitally designed custom abutments using bases or pre-milled blanks are required to be either manufactured by a Validated Milling Center (VMC) or designed and manufactured according to the 510(k) cleared digital dentistry workflow labeling.
Understanding the options and the differences requires a knowledge of the FDA's product codes for these 510(k) cleared devices. Ti bases and blanks alone in a 510(k) clearance are classified under the product code NHA (endosseus dental implant abutment), for which the dental laboratory must operate as a VMC.1 A combination 510(k) clearance with both NHA and the dental abutment design software product code PNP,2 however, involves a different set of requirements from the FDA.
This article will refer to open and closed digital workflows. The product code NHA 510(k) requiring a VMC is the open system option, and the combined product code PNP/NHA 510(k) will be referred to as the closed system.
The Open System
The VMC is a dental laboratory that, under an agreement, is a contract manufacturer for the 510(k) holder/supplier of those digitally designed custom abutments from bases or pre-milled blanks. This is the same as when dental laboratories are contract manufacturers for companies that hold the 510(k) clearances to manufacture sleep appliances or private labeled orthodontic aligners. These contract manufactures need to establishment register, list the products they are manufacturing with the FDA, and operate under a quality system.
The author asked Andrew I. Steen, Acting Assistant Director of the Implantable Dental Devices Team at the FDA Dental Division, to answer the following question: What is a Validated Milling Center? "Validated Milling Center is a dental implant/abutment industry term for what the FDA considers to be a manufacturing partner more aptly defined as a contract manufacturer," Steen says. "Like a contract manufacturer of any Class II medical device, a Validated Milling Center is responsible for registration/listing of the facility and devices produced as well as implementation of manufacturing procedures in line with quality system regulations."
A tremendous advantage of operating in this open system is that a laboratory can be a contract manufacturer for multiple suppliers of bases and pre-milled blanks. They will be able to select the mills used in their laboratory, their CAD software, and any materials used in processing. In an open system, it is the laboratory that decides which manufacturing process to incorporate.
The advantage of operating under a digital quality system is that documenting laboratory activities involved in maintaining equipment is easier; this assures that investments are properly maintained and operate with consistent quality, and it can extend the operational lives with proper maintenance. A digital quality system's maintenance reporting on each equipment asset in the laboratory is invaluable information needed to assure that you reap the most benefits from your equipment investments.
The digital quality system also provides records and reporting on remakes and reworks to identify areas to improve case manufacturing and eliminate costly redoing of cases.
Another advantage to a single FDA establishment registration is that it can cover the manufacturing of many different devices. Having more appliances and devices listed in your FDA establishment registration makes the registration fee more reasonable and manageable. A laboratory registering for the purpose of fabricating custom implant abutments can expand its offered services as an FDA-registered medical device manufacturer to add the processing of sleep appliances, surgical guides, and the private labeling of orthodontic aligners, for example.
The Closed System
A closed system dictates through its labeling the digital dentistry workflow that integrates multiple components. The manufacturing processes and components, in quality assurance terms, are detailed and described in what the FDA calls labeling-which includes instructions for use, indications for use, and the minimum and maximum device manufacturing specifications.
For bases, this includes scan files from intraoral and laboratory (desktop) scanners, CAD software, CAM software, ceramic material, milling machines, and associated tooling and accessories. For pre-milled blanks, it includes scan files from intraoral and laboratory (desktop) scanners, CAD software, CAM software, milling machines, and associated tooling.
The language in the PNP/NHA 510(k)-cleared digital dentistry workflow states that its purpose is to expand the abutment system under the 510(k) clearance to add the ability for the subject device base abutments and pre-milled (blank) abutments to be manufactured via a digital dentistry workflow by following the specific use scan files from intraoral and laboratory (desktop) scanners, CAD software, CAM software, ceramic material, milling machines, and associated tooling and accessories.
The company's cleared PNP/NHA 510(k) is very specific regarding all that is used in the manufacturing process. A closed system 510(k) cleared for bases on August 15, 2023, included the following digital workflow labeling:
The following components are intended to be used for scanning, designing and manufacturing of ceramic mesostructures for the Implant Titanium Base Abutment:
Lab scanner: Medit/Identica T500 3D Scanner (Medit Corp)
CAD software (PNP): 3Shape Abutment Designer & Abutment Design (3Shape A/S - K151455 & K200100) and exocad AbutmentCAD (exocad GmbH - K193352)
Ceramic material: Katana™ Zirconia (Kuraray Noritake Dental, Inc. - K143439)
Milling machine: Ceramill Motion 2 (Amann-Girrbach AG)
Milling software:Ceramill Match 2 CAM Software (Amann Girrbach AG)
Cement: RelyX™ Luting Plus Automix Cement (3M ESPE Dental Products - K111185)
Another closed system PNP/NHA 510(k) clearance for Ti bases and blanks on March 9, 2023, stated:
The digital dentistry workflow uses scan files from intra-oral and lab (desktop) scanners, CAD software, CAM software, ceramic material, milling machine and associated tooling and accessories. The digital workflow includes the following products (not subject devices of this submission)
Ceramic material: VITA YZ ST and VITA YZ XT (K180703)
Cement: Ivoclar Vivadent Multilink Hybrid Abutment Cement (K130436)
Intraoral Scanner: 3Shape TRIOS A/S Series Intraoral Scanner (510(k) exempt under 21 CFR 872.3661)
Desktop scanner: 3Shape D900 Dental Lab Scanner (510(k) exempt under 21 CFR 872.3661)
Abutment design software: 3Shape Abutment Designer Software (K151455)
Milling machine: VHF R5 by vhf camfacture AG with DentalCAM and DentalCNC 7 software
In regard to a letter questioning whether similar VMC requirements exist for a dental laboratory working with a closed system, the author received the following information from Steen at the FDA Dental Division: "At this time, there is no requirement that a user (e.g. dental laboratory) of an FDA-cleared device with the PNP product code to follow quality system regulations for on-label use of the device. The 21 CFR 820 requirements mentioned are the responsibility of the 510(k) holder, specification developer, and registered manufacturer of the NHA/PNP system components. However, the user of the NHA/PNP FDA-cleared device must follow the provided/referenced labeling, which may include requirements or information related to equipment maintenance, process controls, complaints, and/or corrective and preventative actions."
Clearly, the FDA places the "policing responsibility" on the supplier or manufacturer of the bases and blanks. This is a very difficult task for them to manage, and as all dental laboratories operate under the FDA's Establishment Registration Exemption cited in 21 CFR 807.65(i), the FDA will not be able to enforce the on-labeling requirement. Should a laboratory decide to not follow the closed system labeling as detailed in the supplier's PNP/NHA 510(k) and go off-label, there could be consequences if the FDA discovers such activity. Going off-label would entail not following the manufacturing details listed in the labeling. The FDA could present the laboratory with a cease-and-desist order prohibiting the laboratory from manufacturing devices off-label until they either demonstrate that they are following the labeling, become a VMC, or file for their own 510(k) submission. Will this situation bring more change to the industry in terms of the FDA being able to enforce the labeling of the PNP/NHA 510(k)?
Selecting the best options for your dental laboratory can hinge on whether you are already registered with the FDA for other devices or appliances. Adding another device can be accomplished at no cost to the laboratory. Consider the new equipment investment to meet the FDA labeling guidance of the supplier you decide to work with; your existing equipment and whether it meets the labeling specifications for one of the PNP/NHA options; the overall case volume involving these components; and, of course, the information provided by the suppliers themselves.
The decision process is not clear-cut, but having options is much better than being restricted to operating as a VMC or outsourcing your cases.
About the Author
Carson City, NV
1. Product Classification. U.S. Food & Drug Administration website. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPCD/classification.cfm?ID=NDP. Updated October 23, 2023. Accessed October 24, 2023.
2. Product Classification. U.S. Food & Drug Administration website. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpcd/classification.cfm?id=1450. Updated October 23, 2023. Accessed October 24, 2023.