The periotest method, an objective, noninvasive clinical diagnostic method, is a dynamic procedure that measures the resistance of the periodontium to a defined impact load. It has been reported that Periotest values depend to some extent on tooth mobility, but mainly on the damping characteristics of the periodontium. Nevertheless, the eal clinical meaning of the measurements and some important limitations of the Periotest measuring principle still seem to be poorly understood. In the present study, the relationship between damping characteristics of periodontal tisues and tooth mobility was investigated. The best correlations between tooth deflection and Periotest values were found for teeth showing a certain degree of clinical mobility (R2 from .79 to .91). Nevertheless, this correlation was clearly lower when only healthy subjects were examined (R2 from .43 to .54). The better correlation found for forces greater than 1.0 N indicates that the damping characteristics assessed with the periotest method are related to secondary tooth movement. The Periotest methodology, measuring principle, and limitations are critically reviewed.