Introduction: In the few existing long-term clinical trials on posterior composites, patient attrition (typically 5-10% per year) substantially limits quantity and true quality of results. Suspicions exist that many missing values underestimate actual changes.
Objective: Assess the impact of missing values using a novel estimation method for missing values in clinical trials of posterior composite wear over 10-years.
Methods : Two composites (1981-1991 FulFil [F70], conventional; 1998-2008, SureFil, packable; Dentsply-Caulk) were placed previously with conventional techniques, recalled (0.5-1-2-3-5-10y; 0.5-1-2-4-5-10y), and monitored with impressions for wear (Leinfelder method, baseline-subtracted, 3 highly-calibrated clinicians). Restorations were Class I and II in first or second molars with at least half of all possible wear values for inclusion. Regression of occlusal wear for each restoration versus log time (y=m(ln(x)+b) was determined to calculate missing values. Artificially completed data sets (W2) were compared to missing-value sets (W1) by one-way ANOVA (p≤0.05, Bonferroni).
Results : Means (X) and standard deviations (sd) are reported below with no significant differences (>0.05) between W1 and W2 for any recall for either composite. Surprisingly, increased values had little effect. While insignificant, the 10y W2 packable trend indicated a potential overestimate.
Conclusion: Added values from estimations for long-term trials did not affect results.
Acknowledgment: Supported indirectly by Dentsply-Caulk.
Keywords: Clinical trials, Composites and Wear