Table 3. Characteristics of the included studies: PICOS, follow-up period, and main findings.

PICOS: patient/population, intervention, comparison, and outcomes; RCT: randomized controlled trial; NAC: non-accelerated control; compound design: consisting of both parallel and split-mouth; MOPs: micro-osteoperforations; LLLT: low-level laser therapy; Exp: experimental; M: male; F: female; RTM: rate of tooth movement; TTM: time of tooth movement

Authors (year, country)	Methods		Participants	Type of Malocclusion	Interventions			Outcomes
	Study design	Treatment comparison	Patients (M/F); age (years)		Type and site of intervention/technical aspects of interventions	Application frequency	Follow-up time	Primary and secondary outcomes
Multiple methods of acceleration (two or more different methods of acceleration)
Abdelhameed and Refai, 2018, Minya, Egypt [34]	RCT (compound design)	MOPs/NAC vs. LLLT/NAC vs. MOPs + LLLT/NAC	Patients (M/F): 30 (NR/NR). Control: 30. Exp: 30. Age (years): 15-25	Patients who need to extract maxillary 1st premolars and maxillary canine retraction	MOPs: 12 MOPs (with a depth of 6 mm) were applied by miniscrews (six MOPS were done buccally and six palatally). LLLT: a soft laser (wavelength: 810 ± 10 nm) was used from buccal and palatal surfaces along the root of the U3	MOPs: the technique was repeated every two weeks. LLLT: the application of laser was at the beginning of a canine retraction, after three days, one week, two weeks, then every two weeks for three months	3 months	Primary outcome: RTM (mm/week)
Farid et al., 2019, Cairo, Egypt [36]	RCT (split-mouth design)	Corticotomy + LLLT vs. corticotomy	Patients (M/F): 16 (0/16). Control: 16. Exp: 16. Age (years): 17-25	Class I or Class II (Angles’ classification) malocclusion cases needed to extract 1st premolars	Corticotomy: after an elevated full-thickness flap, 10-15 corticotomy perforations with a depth of 1-2 mm were done from the distal surface of the 2nd premolar to the mesial surface of the U3, using a round bur. LLLT: InGaAs diode laser (wavelength: 940 ± 10 nm) was applied at the middle point of the U3 root on buccal and palatal surfaces for 240 seconds	LLLT: the application of laser was on the 1stday of retraction, after one, two, and three weeks, then every two weeks. The application of LLLT started on the same day of surgery	4 months	Primary outcome: RTM (mm/month). Secondary outcomes: molar anchorage loss
Yousif et al., 2019, Tanta, Egypt [16]	RCT (compound design)	Multiple osteoperforation/NAC vs. multiple osteoperforation + corticotomy/NAC	Patients (M/F): 30 (NR/NR). Control: 30. Exp: 30. Age (years): 15-18	Patients who need to extract 1st premolars and maxillary canine retraction	Multiple osteoperforation: after an elevated flap, 3 MOPs (2-mm wide, 2-mm deep, and 2 mm apart from each other) were done along the mesial and distal side of the U3 root, using round surgical bur. Corticotomy: after an elevated flap, a corticotomy cut along the distal side of the U3 root was carried out		Until the completion of the canine retraction	Primary outcome: TTM (days). Secondary outcomes: pain and discomfort., canine angulation
Repetition of an acceleration method
Sivarajan et al., 2019, Kuala Lumpur, Malaysia [38]	RCT (compound design)	MOP 4-weekly maxilla/8-weekly mandible/NAC vs. MOP 8-weekly maxilla/12-weekly mandible/NAC vs. MOP 12-weekly maxilla/4-weekly mandible/NAC	Patients (M/F): 30 (7/23). Control: 30. Exp: 30. Age (years): 18 years and above	Patients who need to extract four first premolars and canine retraction	MOPs: 3 MOPs (with a depth of 3 mm and 2 mm apart from each other vertically) were applied using an Orlus screw (through the buccal mucosa adjacent to the extraction site)	MOPs: the technique was repeated every 4 weeks in Group 1 (4 sessions of MOPs), 8 weeks in Group 2 (2 sessions of MOPs), and 12 weeks in Group 3 (2 sessions of MOPs)	4 months	Primary outcome: RTM (mm/month). Secondary outcomes: pain and its impact on daily function
Asif et al., 2020, Kuala Lumpur, Malaysia [35]	RCT (compound design)	MOP 4-weeks/NAC vs. MOP 8-weeks/NAC vs. MOP 12-weeks/NAC	Patients (M/F): 30 (NR/NR). Control: 30. Exp: 30. Age (years): 18 years and above	Patients who need to extract four first premolars and canine retraction	MOPs: 3 MOPs (with a depth of 3 mm and 2 mm apart from each other vertically) were applied using an Orlus screw (through the buccal mucosa of the extraction site)	MOPs: the technique was repeated every 4 weeks in Group 1 (4 sessions of MOPs), 8 weeks in Group 2 (2 sessions of MOPs), and 12 weeks in Group 3 (2 sessions of MOPs)	3 months	Primary outcome: RTM (mm/month)
Jaiswal et al., 2021, New Delhi, India [37]	RCT (split-mouth design)	One-time MOP vs. two-time MOP	Patients (M/F): 16 (4/13). Control: 16. Exp: 16. Age (years): 15-25	Patients who need to extract 1st premolars and maxillary canine retraction	MOPs: 3 MOPs (with a depth of 7 mm) were applied using Propel (through the buccal mucosa of the extraction site)	MOPs: the technique was repeated one month after the first MOP in the Exp Group	6 months or until the completion of the canine retraction	Primary outcome: RTM (mm/month), molar anchorage loss, canine angulation