An evaluation of clinical tooth mobility measurements.

This study evaluated the reliability and reproducibility of the modified Miller Index of horizontal tooth mobility. Each of three periodontists utilizing the modified Miller Index assessed the horizontal tooth mobility of 50 teeth in five subjects. The same teeth were also evaluated by the periodontometer. The results of these two methods were then compared. It was found that: (1) there were a high positive correlation between the periodontists' (pooled) assessment of clinical tooth mobility and the measurements of the periodontometer, (2) in any given patient the three periodontists (pooled) were highly accurate in their ability to rank teeth in order of their mobility as determined by the periodontometer, and (3) the periodontists (individually) were not as consistent when comparing teeth with the Miller Index across different subjects. The periodontists did not accurately utilize the Miller Index as it was originally described. It appears that the periodontists either ignored the reference to 1 mm in the description of the Miller Index, or they were unable to estimate what constitutes 1 mm of movemnet in the mouth. The periodontists all consistently scored as a 2 degrees mobility a tooth that moved approximately 0.5 mm not 1.0 mm as described by Miller. It is suggested that the modified Miller Index as described here provides an efficacious system for evaluating horizontal tooth mobility. It provides accurate, reproducible mobility scores in clinical studies requiring an estimation of this parameter. However, for individual teeth, when the clinician or researcher is trying to evaluate the effects of therapy on the periodontium and relatively few evaluation are made, the modified Miller Index may not provide the required degree of sensitively.