Table 1. Study and patient characteristics of the reviewed studies.

Studies	Study design/sampling method	No. of patients	Age range/years	Antagonist	No. of crowns	Setting	Dropout
Etman 2008	Prospective RCT	48 (17 M, 31 F)	20–60	Molars and premolars	90	University hospital	—
Suputtamongkol 2008	Prospective	30 (5 M, 25 F)	20–26	Molars and premolars	30	University	—
Silva 2011	Prospective RCT	31 (8 M, 23 F)	24–62	Molars and premolars	36	University	—
E-Upshaw 2012	Prospective RCT	31 (8 M, 25 F)	24–62	Molars and premolars	36	University	1 patient and other patient after 1 year
E-Upshaw 2013	Prospective RCT	32	≥18	Molars and premolars	37	University	1

RCT, randomized controlled trial; M, male; F, female; No., number.