Table 7. The main findings of the studies included in this systematic review.

OST: open surgical technique; CST: closed surgical technique; PPD: periodontal pocket depth; GR: gingival recession; KT: width of the keratinized tissue; BS: bone support; CAL: clinical attachment level; GI: gingival index.

Study	Groups	Velocity and duration of orthodontic traction/treatment	Periodontal outcomes/root resorption	Patient-reported outcomes
Smailiene et al. (2013) [7]	OST vs. CST group	Mean treatment time was 28.41 ± 4.96 and 32.19 ± 11.73 months in OST and CST group, respectively (p > 0.05). Mean eruption/extrusion time was 3.05 ± 1.07 and 6.86 ± 4.53 months for OST and CST group, respectively (p < 0.01)	Mean PPD was 2.2 ± 0.55 mm and 2.01 ± 0.42 mm on the impacted canine side and contralateral side, respectively (p < 0.05), with no significant differences in PPD and BS between test groups. No significant differences in GR and KT between groups and between the test and contralateral sides. In comparison with the contralateral side, differences were found in BS at the mesial side of the canine and the distal side of the lateral incisor	Not evaluated
Smailiene et al. (2013) [42]	OST vs. CST group	Not evaluated	No significant differences in PPD between test groups. Mean PPD on the impacted canine side was 2.14 mm (SD = 0.38) and 2.28 mm (SD = 0.69) in the OST and CST group, respectively, while, on the contralateral side, it was 1.95 mm (SD = 0.38) and 2.20 mm (SD = 0.42) in the OST and CST group, respectively. No significant differences in GR between groups and between the test and contralateral sides. BS did not differ significantly between the groups (mean bone support of 89.33%; SD = 6.87%) in the OST group and (86.66%; SD = 6.94%) in the CST group	Not evaluated
Parkin et al. (2012) [17]	OST vs. CST group	Not evaluated	Not evaluated	In the two groups, the pain lasted for “several days” in 60% of the sample. Three patients in the CST group and six patients in the OST group reported that the pain lasted for more than several days, but this was not statistically significant. Twenty-eight of 31 participants (90%) in the OST group required pain relief compared with 23 of 29 (79%) in the CST group, which was not statistically significant. The difference in pain duration between groups was not significant (p = 0.161)
Parkin et al. (2013) [41]	OST vs. CST group	Duration of active traction: 10.2 months; SD = 4.2 and 13.2 months; SD = 8.5 in OST and CST group, respectively	Mean CAL difference between OST and CST groups was 0.1 mm (open: 0.5 mm, SD = 0.8; closed: 0.6 mm, SD = 0.6; p = 0.782). Eight subjects (28%) in the CST group and 12 subjects (36%) in the OST group showed root visibility at the mid-palatal point between zero and 2 mm (P = 0.464). In the CST group, nine subjects (31%) showed recession of at least 1 mm on the mid-buccal aspect of the operated canine (1 mm in seven subjects, 2 mm in subjects). In the OST group, eight subjects (24%) showed recession of at least 1 mm (1 mm in five and 2 mm in three subjects; p = 0.774)	Not evaluated
Heravi et al. (2016) [15]	Two miniscrews vs. transpalatal arch	The mean eruption time was 5.2 months in the control group and 5.1 months in the experimental group (p = 0.125)	No significant difference in the volume of canine root resorption and in GI between the two groups (p = 0.937). The volume of lateral incisor root resorption in the control group was significantly greater than in the experimental group (nearly fourfold)	After three weeks, higher pain levels were reported in the control group (p = 0.012); but, at the end of treatment, this difference was not statistically significant (p = 0.769). In the experimental group, the pain level was determined one day after the placement of miniscrews, and the mean value was 2.1
Gharaibeh and Al-Nimri(2008) [12]	OST vs. CST group	Not evaluated	Not evaluated	On the first postoperative day, six patients (33%) in the CST group and four patients (22%) in the OST group reported severe pain (p = 0.123). On the second postoperative day, only two patients in the OST group continued to experience severe pain whereas none in the CST group reported severe pain. Neither group reported any severe pain after the second postoperative day
Björksved et al. (2018) [40]	OST vs. CST group	Not evaluated	Not evaluated	The number of surgical complications within four weeks post-surgery was similar in the two groups. On the evening of operation day, significantly higher pain scores were at the injection of local anesthetics in the CST group, while post-surgery pain showed significantly higher pain scores in the OST group. Significantly more pain level (p = 0.010) in the seven days post-surgery was in the OST group
Fischer (2007) [31]	Corticotomy-assisted canine treatment vs. conventional treatment	Significantly higher tooth movement velocity was recorded in all corticotomy-assisted canines and the treatment time was reduced by 28-33%	No clinical differences were recorded in the periodontal probing and bone levels between the two groups	Not evaluated
Dehis et al. (2018) [43]	Vitamin C injection (intervention group) vs. conventional traction (control group)	Statistically, a greater mean area percent of the movement rate was recorded in the intervention group compared to the control group (1.08 ± 0.376, 2.25 ± 0.274, respectively; p < 0.003). Clinically, significant improvement was reported in the movement rate in the intervention group (2-2.5 mm/month) compared with the control group (0.5-1.5 mm/month)	No intra- (p = 1.000) or intergroup statistical significant difference (p = 0.416) was reported in the KT between the pre- and postoperative values. No statistically significant differences were found in the gingival margin level between both groups. The intragroup analysis showed statistically significant differences in the alveolar bone thickness (p = 0.000). While the intergroup analysis of the postoperative results in both groups showed statistically and radiographically significant differences (p = 0.002)	Not evaluated