Surrogate Parameter as Outcome Measure in Clinical Trials

Objective: The aim of the study was to establish a surrogate parameter assessing dental, technical, subjective (dentist or patient), and biological properties in clinical trials. The developed surrogate parameter and its subscores focus on achieving comparable results in clinical trials quickly, with few patients and cost-effective.

Method: One-hundred anonymous data sets of a clinical trial carried out in 2001 were analyzed. At the time of the study, the patients were fitted with provisional restorations made of three self-curing resins (Luxatemp, DMG;  Protemp3Garant, 3M Espe; DentalonPlus, Heraeus Kulzer; Germany) during standard prosthetic treatment. Differences of the following criteria between pretreatment and post-treatment were analyzed: integrity of the temporary restoration, occlusal and proximal contacts present, patients’ satisfaction, handling parameters, plaque index, gingival index, bleeding on probing. Weighting factors were introduced to influence the selectivity of the assessment (tolerance).

Result: None of the materials investigated caused alteration of gingival health or increased plaque adherence in terms of the median values. The clinical reliability of the temporary restorations was high but patients’ satisfaction worsened from first to second follow-up visit. Weighted ratings of the surrogate parameter resulted in a better average evaluation than unweighted. Taking patients’ and biological weighting into consideration, the average evaluation is 1.3 and 1.5 on a scale of 1 (very good) to 5 (poor). The average evaluation worsens to 2.7 and 2.8 according to dentists’ and technical weighting but remains considerably better than the unweighted evaluation (3.4).

Conclusion: The developed surrogate parameter seems to be adequate showing the complete spectrum of clinical changes. A dental, technical, subjective (dentist or patient), and biological treatment assessment can be performed. By adjusting weighting factors the focus of the subscores can be changed and the parameter can be used for a broad application in therapy studies.