Figure 2. Kaplan-Meier plots by subgroup (A) showed that the survival probability was higher for posted restorations from the six-month recall on. The gap between the two curves became greater as time progressed. Kaplan-Meier plots constructed for the groups defined as 4, 3, 2, and 1 preserved coronal wall (B–F, respectively, N at baseline = 40 in each group) indicated that the probability of tooth failure was higher in the presence of a reduced portion of crown dentin. Also, post placement appeared to contribute more to survival probability the less the coronal structure was retained, since the gap between the "post" and "no post" plots increased as the degree of hard-tissue loss increased.