The location of the periodontal probe tip in health and disease.

The periodontal probe is used clinically to measure pocket depth and the level of periodontal attachment. In order to be a more reliable, noninvasive method of assessment, it is necessary to investigate the position of the tip of the probe when at rest in the dentogingival junction. Probes were assessed for accuracy, and those closest to a standard millimeter scale were used to make pressure-cast, gold-coated, acrylic replicas. The replicas were placed in the gingival crevice of Rhesus monkeys with normal gingiva and with experimentally-induced gingivitis and periodontitis. Clinical, histologic, and histometric evaluations were made in block sections. In normal gingiva and in areas of gingivitis the probe tip stopped at the base of the crevice and was contained within epithelium. In periodontitis the probe sometimes penetrated the epithelium and stopped at the level of the connective tissue attachment. Even with gentle probing there was slight tearing and distortion of the gingiva at the base of the pocket. It was concluded that probing depth estimates indicated the level of a healthy dentogingival junction but did not differentiate between epithelial and connective tissue attachment.