Table 2.

Differences Between Primary and Surrogate Outcomes in Clinical Trials in the Field of Prosthodontics

Primary Outcomes	Surrogate Outcomes
Reflect unequivocal evidence of tangible benefit to the patient	Include measures that are not of direct practical importance but are believed to reflect outcomes that are important as part of a disease/treatment process
Examples	Corresponding examples
● Tooth survival	● Pocket depth
● Secondary caries	● Open margins
● Implant survival	● Peri-implant bone level
● Patient satisfaction	● Prosthesis retention/support
Endpoints are “harder” and difficult to measure and studies can be more expensive.	Endpoints are “softer” and easier to measure and studies are relatively inexpensive.
Can have a direct impact on changes in clinical practice and/or changes in public health policies.	Do not have a direct impact on changes in clinical practice or changes in public health policies.

Note: Adapted from Dent Clin North Am, 58(1), Bidra AS. Evidence-based prosthodontics: fundamental considerations, limitations, and guidelines. Dent Clin North Am. 1–17. Copyright 2014, with permission from Elsevier.35