Table 3.

Reference standard related domains

Authors	Reference standard	Target condition	Time point of conducting the reference standard
Motoyoshi et al. [6]	Three-dimensional cone beam computed tomography	No root contact One point contact 2 or more points of contact	After the application of an orthodontic force of 2 Newton
Chen et al. [84]	Two-dimensional radiographs and histology	Contacting or damaging the root surface	3, 12, or 24 weeks (depending on the subgroup) after conducting the index test
Brisceno et al. [25]	Two-dimensional peri-apical radiographs	Damaging the root	Immediately after conducting the index test
Wilmes et al. [33]	Digital scanning of histological slides	No root contact Unilateral root contact Bilateral root contact, i.e. penetration	After the preparation of histological slides
McEwan [32]	Three-dimensional cone beam computed tomography	No root contact Root contact Root penetration	Immediately after conducting the index test

All data in this table represent those reported in the original manuscript. Additional data obtained through our protocol for ‘Contacting authors’ are not included in this table