Milling disc traceability in the lab: batch, MDR and archive

When a material manufacturer announces a problem with a lot of zirconia, the lab has to answer one question fast: which restorations were made from it. Without traceability, the answer takes days of searching through delivery notes. With it, it takes a search. This post is for dental labs that mill in-house or through a milling center and it explains what the MDR asks for custom-made devices, which data to record and how to connect a restoration to its disc.

What the MDR asks of a dental lab

Under Regulation (EU) 2017/745, a dental restoration made for one patient on a prescription is a custom-made device. For each one, the lab draws up the statement described in Annex XIII and keeps documentation of how the device was designed and manufactured, available to the competent authorities. The statement must be kept for at least 10 years after the device is placed on the market and at least 15 years for implantable devices.

The regulation does not prescribe a specific format for material records. It requires documentation that lets the lab show how the device was made. Recording the material and its lot for every job is how most labs meet that in practice and it is what makes a lot recall manageable. The post on MDR and design files covers the regulatory side of outsourced design and milling.

Which data to record

For each disc:

unique disc number
material, product name and manufacturer
lot number and expiry date if stated
shade and height
date of first use

For each job:

job or case number and patient reference as used in the lab’s records
type of restoration and teeth
disc number
date of milling and sintering program used
who checked the restoration before delivery

The two records meet in the disc number. From a job you find the disc and from the disc the lot. From a lot you find every disc and from every disc every job.

Connecting the restoration to the disc

The link fails most often at the mill. A job milled from “the A2 disc in the machine” with no number recorded cannot be traced. A few habits close the gap:

Number every disc when it is unpacked, before it goes into the mill.
Use the disc number as the name of the disc in the CAM software.
Record the disc number in the job as soon as the job is nested, while the disc is still in the machine.
Keep partially used discs in a numbered place with their record. The post on reusing partially milled zirconia discs covers storage and nesting.

When the milling is outsourced

When a milling center produces the restoration, it is a supplier to the lab. The lab should receive the material and the lot with each delivery, or have them available on request, and store them in its own job record. A milling center that cannot state the lot of a delivered restoration leaves a gap in the lab’s documentation.

Keeping the archive

Records have to be kept for the required time and found again when needed. A spreadsheet or a lab management program both work. What matters is that a search by lot returns every job. The archive of the design files is a separate topic, covered in the post on exocad DentalDB.

Labs that want to set up the numbering, the records and the link to the CAM software in one pass can book workflow consulting.

Sources

Regulation (EU) 2017/745 on medical devices, Article 52 and Annex XIII, on EUR-Lex
MDCG 2021-3, Questions and answers on custom-made devices (European Commission)

Frequently asked questions

Does the MDR require the lab to record the material lot?

The regulation requires the lab to document how each custom-made device was designed and made and to keep the Annex XIII statement. Recording the material and its lot for each job is the usual way to make that documentation traceable if a material problem or a complaint comes up.

How long must the documentation be kept?

The Annex XIII statement must be kept for at least 10 years after the device is placed on the market and at least 15 years for implantable devices. National rules can add requirements, so check them for your country.

What is the simplest way to link a restoration to its disc?

A unique disc number used everywhere: on the disc, in the CAM file name and in the job record. Each job then stores the disc number and the disc record stores the material and lot.

Is a paper register enough?

It can be, if it is complete and kept for the required time. A digital record is easier to search, which matters when you need to find every job made from one lot.