A 3-year longitudinal study of the position of the gingival margin in man.

The position of the gingival margin of the incisor and canine teeth, indicated by clinical crown height, was measured using a standardised photographic technique, in 30 dental students over a 3-year period. There was a progressive increase in mean clinical crown height during this period, suggesting that continual passive eruption of the teeth was occurring. There was a significant slowing in the rate of change over the period 1975-1977 for tooth 33, the reason for which is unknown.