Multilevel survival analysis of amalgam restorations amongst RAF personnel.

Objective: To introduce the concepts of multilevel survival analysis through an investigation into the longevity of amalgam restorations.

Basic Research Design: The multilevel Cox proportional hazard model is illustrated using amalgam restoration data comprising three levels: repeated restorations at level-1, teeth at level-2, and subjects at level-3. The outcome was duration of amalgam restoration survival.