In the Casa Pia study in Portugal (1986–1989), 1,748 posterior restorations were placed and 177 (10.1%) of them failed during the course of the study.
I Casa Pia-studien i Portugal (1986–1989), gjordes 1748 upprepade restaurationer och 177 (10,1 %) av dem bedömdes ha misslyckats under studiens gång.