[Research methods in dentistry 1. Methods to quantify retention of complete dentures].

Retention is not an unambiguous variable. The degree of retention is dependent on biologic and physiologic properties of a complete denture and the denture-bearing and surrounding tissues. Quantifying retention forces of a complete denture can be carried out with three types of methods: subjective methods, methods with clinical more or less objective criteria, and nearly entire objective methods using measurement equipment. The subjective and most of the methods with clinical criteria are not or little reliable. However, for epidemiological research the methods with clinical criteria are very pragmatic. Of all objective methods using measurement equipment, the gnathodynamometer is the only apparatus with proven reliability.