Probing force in relation to probe penetration into the periodontal tissues in dogs. A microscopic evaluation

In four beagle dogs, periodontal tissue breakdown was experimentally induced around the upper left premolars (P1, P2 and P3). Wooden probes were inserted mesially and distally to each premolar. Six different probing forces were used in each dog. Microscopic examination showed: 1) the presence of an intact layer of epithelium between the probe tip and the connective tissue in 21 of 23 specimens. 2) an increasing compression of the connective tissue with increasing probing force, without penetration of the probe tip into the connective tissue.