Table 3. Characteristics of the included studies.
M: Male, F: Female, RCT: Randomized clinical trial, PGD: Parallel-group design, SLBs: Self-ligating brackets, Exp: Experimental, mW/cm2: Milliwatts per centimeter squared, LED: Light-emitting diode, SMD: Split-mouth design, LLT: Low-intensity laser therapy, nm: nanometer, RTM: Rate of tooth movement, CBs: Conventional brackets, VA: Vibrational appliance, IL-1β: Interleukin-1 beta, GCF: Gingival crevicular fluid, PD: Periodontal depth, LFV: Low-frequency vibrations, Hz: Hertz, mm: Millimeter, CCT: Controlled clinical trial, LILT: Low-intensity laser therapy, J/cm2: Joule per cm2, J: Joule, FC: Flapless corticotomy
| Study | Methods | Participants | Type of Malocclusion | Interventions | Outcomes | ||
| Authors, year of publication, and country | Study design | Treatment comparison | Patients (M/F), Age (years) | Type and site of intervention/technical aspects of interventions | Follow-up time | Primary and secondary outcomes | |
| Charavet et al. 2016 Belgium [33] | RCT (PGD) | (SLBs + Piezocision) vs. SLBs | Patients (M/F): 24 (9/15) Control: 12, Exp: 12 Mean age (years): Control: 27± 7 Exp: 34±8 | Patients with minimal to moderate maxillary and mandibular anterior crowding (non-extraction treatment plan) | Vertical interproximal microincisions were created below each interdental papilla | Until complete the overall orthodontic treatments | Primary outcome: the treatment time (days) Secondary outcomes: - periodontal health - alveolar crest changes - one and gingival healing - analgesic intake - patient-centered outcomes |
| Nahas et al. 2016 United Arab Emirates [35] | RCT (PGD) | (SLBs + Infra-red light) vs. SLBs | Patients: 40 Control: 20, Exp: 20 Mean age (years): Control: 21.1±10.2 Exp:21.8±5.3 | Patients with lower anterior crowding (non-extraction treatment plan) | Irradiation of the lower anterior segment at a wavelength of 850 nm and a power output of 90 mW/cm2 for 20 min daily using an extraoral LED device | Until completing the leveling and aligning phase | Treatment time |
| Qamruddin et al. 2017 Pakistan [36] | RCT (SMD) | (SLBs + LLT) vs. SLBs | Patients (M/F): 22 (11/11) Mean age (years): 19.8±3.1 | Patients with Angle Class II Division 1 malocclusion (required extraction of maxillary first premolars bilaterally) | A gallium-aluminum-arsenic diode laser with a wavelength of 940 nm in a continuous mode was applied at 5 points buccally and palatally around the canine roots on the experimental side. Laser irradiation was applied at baseline and then repeated after 3 weeks for 2 more consecutive follow-up visits. | Every 3 weeks for 3 more consecutive visits | Primary outcome: RTM (mm/3 weeks) Secondary outcomes: pain |
| Kalemaj et al. 2017 Italy [34] | RCT (PGD) | CBs vs. SLBs vs. (SLBs+ VA) | Patients (M/F): 33 (14/19), CBs: 11, SLBs: 11 SLBs + VA: 11, Mean age (years): CBs: 12.9 ± 1.85, SLBs: 13.3 ± 2.8, SLBs + VA: 13.1 ± 0.07 | Patients with lower anterior crowding (non-extraction treatment plan) | Patients were instructed to use the vibratory device (AccleDent) for 20 minutes daily, beginning from the day of appliance placement and continuing for the first 4 weeks. | The first 3 months of the leveling and aligning phase | Primary outcome: Rate of mandibular incisors alignment Concentration of IL-1β Pain and discomfort Secondary outcomes: Quantity of GCF PD |
| Lalnunpuii et al. 2020 India [38] | RCT (PGD) | (SLBs + LLT) vs. (CBs + LLT) vs. CBs | Patients (M/F): 65 (24/41), SLBs + LLT: 20, CBs + LLT: 20, CBs: 25, Mean age (years): SLBs + LLT: 17.9 ± 1.9, CBs + LLT: 17.9 ± 1.9, CBs: 17.5 ± 1.3 | Patients who need to extract maxillary 1st premolars and en-mass retraction | The low-level laser was applied in the laser groups using a 658 nm (Aluminum, Gallium, Arsenide) semiconductor diode laser. Two irradiations were done both buccally and palatally/lingually from canine to canine. The laser regimen was applied on days 0, 3, 7, and 14 in the first month, then on every 15th day until complete en-masse retraction. | Until complete en-masse retraction | The rate of space closure (mm/months) |
| Kumar et al. 2020 India [37] | RCT (PGD) | (SLBs + LFV) vs. (CBs + LFV) vs. CBs | Patients (M/F): 65 (30/35) SLBs + LFV: 20 CBs + LFV: 20 CBs: 25, Mean age (years): SLBs + LFV: 17 ± 0.80, CBs + LFV: 17.40 ± 0.72, CBs: 16.90 ± 1.1 | Patients who need to extract maxillary 1st premolars and en-mass retraction | The low-frequency vibrations were provided by a custom-made vibratory device. The device was used for 20 minutes daily (during the space closure phase) at a frequency of 30 Hz. | Until completing the space closure | The rate of space closure (mm/months) |
| Chandran et al. 2020 India [40] | CCT (PGD) | Group IA (CBs+ LILT), vs. Group IB (CBs) vs. Group IIA (SLBs+ LILT) vs. Group IIb (SLBs) | Patients (M/F): 32 (NR) Group IA: 8, Group IB: 8, Group IIA: 8, Group IIB: 8, Mean age (years): 19.15 ± 2.26 | Patients with lower anterior crowding (non-extraction treatment plan) | Photobiomodulation with LILT. Gallium Aluminum Arsenide (GaAlAs) diode laser of 808 nm wavelength in a continuous wave of 8 J/cm2 and energy of 2 J per point was used. Laser irradiation was done on the 0, 3rd, 7th, and 14th days in the first month and in intervals of 15 days from the second month until the complete alignment was achieved. | Until completing the leveling and aligning phase | The time taken for the decrowding of the lower anterior teeth (days) |
| Al-Ibrahim et al. 2021 Syria [25] | RCT (PGD) | (SLBs + FC) vs. SLBs vs. CBs | Patients (M/F): 58 (10/47) SLBs + FC: 19 SLBs: 19 CBs: 19 Mean age (years): SLBs + FC: 20.67 ± 2.59, SLBs: 19.98 ± 2.84, CBs: 19.62 ± 2.42 | patients with severe upper crowding who need to extract maxillary 1st premolars. | Incisions 5 to 8 mm long and 3 mm deep were performed 4 mm beneath the papilla. Corticotomies were done only once for each patient at the start of treatment. | Until completing the leveling and aligning phase | Primary outcome: Leveling and alignment time, Secondary outcomes: Periodontal assessment |