BACKGROUND Today, periodontal probing is the best diagnostic tool to assess the health status and attachment level of periodontal tissues. There are, however, doubts as to whether the same method could be used for implants. Experiments comparing peri-implant and periodontal probing provide conflicting results. The impact and interpretation of peri-implant probing are still not sufficiently known. OBJECTIVE The purpose of the present study was to further analyze the histological level of probe penetration in healthy periodontal and peri-implant tissues. METHODS In four beagle dogs, all mandibular premolars were extracted. Three months later, four experimental non-submerged implants were placed in each edentulous premolar region. Six months later, probing depth was determined at the buccal aspect at two of the implants and at the bilateral first mandibular molars. A pressure-controlled probe with a diameter of 0.4 mm and 0.2 N probing force was used. Following the probing depth assessment, a metal periodontal probe tip was inserted into the previously measured depth and attached to the implants and teeth using a composite material. Block biopsies were obtained and prepared for histometric examinations. RESULTS The findings showed that probing resulted in similar probe extension at implants and teeth, that the probe extension corresponded to the extension of the barrier epithelium and that the distance between the probe tip and the bone was about 1 mm in both peri-implant and periodontal tissues. CONCLUSIONS This experiment showed that under healthy conditions, the probe tip penetration in the soft tissues at teeth and implants is similar when a probing force of 0.2 N is used. Probing around implants using a moderate force is a valuable diagnostic tool in the maintenance of implant patients.