The informativeness of attachment loss on tooth mortality

In periodontal clinical trials, clinical attachment level measurements are commonly used as surrogates for tooth loss. Conclusions regarding treatment efficacy in these trials are valid if: 1) the surrogate is informative on tooth loss, and 2) the surrogate captures the effect of treatment on tooth loss. The goal of this study was to evaluate the first criterion: Are serial clinical attachment loss measurements informative on overall tooth mortality?

Young Norwegian men (aged 17 to 35) were first examined in 1969 (n=565) and followed for 26 years with examinations in 1971 (n=381), 1973 (n=292), 1975 (n=245), 1981 (n=228), 1988 (n=202), and 1995 (n=223). Several aspects of the serial attachment loss measurements were related to tooth mortality risk using statistical models that take into account the time-dependent changes of the clinical attachment loss measurements.

The results provided evidence that moderate attachment losses were informative on tooth mortality. Both the lifetime cumulative attachment loss, as well as attachment loss since young adulthood, of > or = 2 mm or > or = 3 mm was informative on tooth mortality. Tooth mortality risk increased as the attachment loss increased; loss > or = 3 mm at the buccal or mesial site increased tooth mortality risk, by 91% (relative risk, 1.91; 95% confidence interval, 1.01-3.60) and 270% (RR, 3.70; 95% CI, 1.83-7.49), respectively.

We concluded that clinical attachment loss was moderately informative on overall tooth mortality in this Norwegian population. Since this finding has now been demonstrated in 3 different populations, the focus of further research should be on evaluating whether the second criterion for a valid surrogate is satisfied: Does clinical attachment loss capture the effect of periodontal treatments on tooth loss?