Table 1. Number* of studies excluded according to the ISO recommendations by property.

ISO recommendations	Mechanical and optical properties
	Compressive strength	Flexural strength	Color	Opacity	Radiopacity
Specimens´ dimension	27	23	5		5
Equipment test speed	34	23
Storage time	4		13
Storage temperature	5
Focus-film distance					1

*The total number of papers presented in the table is higher than 96 that were excluded as some papers did not follow more than one recommendation