Healthcare

The dentist file in practice: WGBO, KNMT and an archive in order

4 March 2026 · 6 min read · DeSnipperaar

The dental practice works with a combination of paper status cards, digital treatment files, X-ray images, periodontal status records, treatment plans and referral correspondence. For each of these parts statutory and professional rules apply to retention and destruction. The WGBO forms the legal framework, the KNMT fills it in with practical guidelines. This article brings the elements together into a workable archive policy.

WGBO as the foundation

Article 7:454 of the Dutch Civil Code (the WGBO) provides that the healthcare provider keeps the patient file for at least twenty years from the last contact, or for as much longer as good healthcare practice requires. For minors the period generally starts at the 18th birthday. In 2020 the period was extended from fifteen to twenty years; old files that existed on 1 January 2020 follow the old period unless the new one is more favourable to the patient.

For an extensive explanation see our article WGBO 20 years for patient files.

KNMT guideline on file keeping

The Royal Dutch Dental Association (KNMT) has a Patient File guideline that fills in the WGBO practically for oral healthcare. Key points:

• Each file contains: identification data, medical history, treatment history, X-ray images with reasoning, treatment plans and informed consent, referrals.
• Notes are accessible to colleagues in cover or takeover.
• The patient has the right of access, copy and correction.
• On transfer of the practice the file goes with it or remains available to the patient.

Special categories

Health data falls under the special categories of article 9 GDPR. That means: processing only on a specific ground (usually performance of the treatment agreement), strict security, limited access and a clear internal authorisation model. On a data breach the notification duty is often directly applicable because of the sensitivity.

The dental file is at once a medical document, a legal piece of evidence and a GDPR-sensitive collection. Each of those three roles calls for careful retention and careful destruction.

X-ray images and periodontal status

X-ray images are part of the file and share the twenty-year retention period. Digital images sit in the practice management system; older analogue exposures (periapical cards, panoramic photos on film) still lie in cabinets at practices digitised between 2005 and 2015.

The periodontal status is a repeated measurement spanning years. The full history belongs in the file, because the trend has clinical relevance. Only after the twenty-year period from last contact has expired does destruction come into view.

When may you destroy?

Three situations call for active destruction:

1. Period expired. Twenty years after last contact (or from the 18th birthday) the file may go, unless the patient has been treated again since (new period) or a longer period is justified by good care practice.
2. Patient requests destruction. Article 7:455 BW gives the patient the right to destruction of (parts of) the file. The provider destroys within three months, unless another person has a substantial interest in retention.
3. Practice closes. On closure files transfer to a successor or to a custodianship arrangement; what remains is destroyed in line with the guideline.

Practical destruction process

A dental practice archive is often a mix of paper (old status cards, X-ray film envelopes, referrals, prints of digital files) and digital data (practice management system, backups, scans). The paper side is best tackled via an annual clear-out round in which everything past its retention period is inventoried, bundled and destroyed. See our comparison mobile shredding versus offsite for the choice between destruction on site or at a distance.

Mobile destruction at the practice

For dental practices, mobile destruction on site is almost always the right choice. Files fall under professional secrecy; they may not leave the building intact. With DeSnipperaar the destruction truck comes to the practice. Paper status cards, X-ray film, referrals and prints go through the shredder on the spot at DIN 66399 P-5. Your team member or practice holder watches through the side window. Afterwards you receive a certificate in the name of the practice. No contract, no minimum, easily fitted into an afternoon's schedule.

Digital side

For the digital side the same logic applies, but with different techniques. Backup tapes and old hard drives containing patient data must be demonstrably destroyed at end of life at H-4 or E-4 level. See also our articles on destroying SSDs and wiping versus destroying a hard drive.

In summary

• WGBO: twenty years from last contact or from the 18th birthday.
• The KNMT guideline fills in practically what belongs in the file.
• Special category GDPR art. 9; strict security and access restriction.
• X-ray images and periodontal status share the file's retention period.
• Mobile destruction at the practice prevents files being lost during transport.

More sector-specific information is on our page for healthcare providers and practices.