Table 2. Study designs of clinical trials.

Studies	Study design	Type of study	Sample size calculation	Measuring method	Method error	Special analysis	Statistics
Clinical
Liou et al. 2004	CT	Retrospective	No	Superimposition; cephalogramms	Yes	—	Adequate
El-Beialy et al. 2009	CT	Prospective	No	Superimposition; dental CT	No	Measured twice after 2 weeks	Adequate
Liu et al. 2011	CT	Retrospective	No	Superimposition; dental CT	Yes	Point registration three times; measured twice; mean	Adequate
Alves et al. 2011	CT	Prospective	No	Superimposition; CBCT	No	Measured twice; mean	Adequate
Wang et al. 2006	CT	Retrospective	No	Superimposition; cephalogramms	Yes	—	Adequate
Hedayati et al. 2007	RCT	Prospective	No	Superimposition; cephalogramms	No	Measured twice; mean	Adequate
Calderon et al. 2011	CT	Prospective	No	Superimposition; occlusal X-ray	No	Cone beam CT for calibration	Inadequate
Lifshits et al. 2010	CT	Prospective	No	Superimposition; cephalogramms	Yes	—	Adequate
Kinzinger et al. 2008	CT	Retrospective	No	Superimposition; cephalogramms	No	Measured twice; mean	Adequate
Animal
Mortensen et al. 2009	CT	Prospective	No	Clinical measurement with digital calliper	No	Repeated measurements	Adequate
Ohmae et al. 2001	CT	Prospective	No	Superimposition of dental radiographs	No	—	Descriptive

CT, clinial trial (without control group); RCT, randomized controlled clinical trial.