Table 1.

Summary of descriptive characteristics and outcomes of interest of the included studies (n = 14).

Author, year	Aim of the study	Sample size	Age/Sex	Study design	Outcomes of interest	Conclusions
Bjorksved, M., et al. 2018	To compare surgery time, complications and patients’ perceptions between closed and open surgical techniques in palatally impacted maxillary canines.	119/ 60CL 59OP	13.4 ± 1.46 75F 44M	Interventional/ Randomized clinical trial	Surgery time did not differ significantly between the interventions. Complications though were more severe in bilateral cases and the patients experienced more pain and impairment in the open group.	There were no statistically significant differences regarding surgery time between the groups. Postoperative complications were similar between the groups in unilateral PDCs, but more common in the open group in bilateral cases. More patients in the open group experienced pain and impairment compared to the closed group.
Blair, G. S., et al., 1998	The records of 96 consecutively treated patients, were reviewed after orthodontic alignment of the exposed teeth (Open technique). The exposed canines, were critically assessed. And the assessment involved scoring for clinical impression, mobility, gingival condition and pocketing, oral hygiene, vitality, and radiographic appearances.	25 patiens and 30 canines/ 30 OP	10.1–30.2 22F 3M	Observational/ Retrospective cohort	Pocket depth was greater in the exposed teeth in comparison with contralateral side. There was no clinically detectable difference in tooth color between the exposed teeth and the control groups. Vitality testing demonstrated that internal controls had a significantly lower response than the exposed canines.	The results indicate that the technique of surgical exposure and orthodontic alignment of ectopic maxillary canines provides a satisfactory method of treatment.
Bollero, P., et al., 2017		14CL	13.5 ± 1.4 8F 6M	Observational/ Retrospective cohort
Caprioglio, A., et al., 2019	To evaluate and compare the existing correlations between periodontal health outcome of palatally impacted maxillary canines and their initial position identified according to the different rates of impaction severity in adolescent patients after their exposure (closed technique) and alignment.	293CL	13.8 ± 1.2	Observational/ Retrospective cohort	α-Angle and d-distance showed no significant differences in the periodontal outcome of palatally impacted maxillary after treatment. The only tested variable showing significant differences was S, since canines with CEJ visible at the end of the treatment presented sectors with a mean score of 1.67, which was significantly different (P < 0.05) when compared to the S-sector for the canines that showed PD < 2 mm at the end of the treatment.	Radiographic variables as α Angle and d-distance seem to not influence the periodontal outcome of the treated impacted canine regardless of the amount of gravity. On the contrary, S sector might play a significant role when higher rates of gravity are present suggesting the possibility in few cases for periodontal damage at the end of treatment.
Caprioglio, A., et al., 2013	The aim of the present study was to evaluate the long-term periodontal response of palatally impacted maxillary canines aligned compared with contralateral spontaneously erupted teeth.	33CL	16.3 ± 3.9 24F 9M	Observational/ Retrospective cohort	The average probing depth values showed no significant clinical differences. Probing depths recorded at the vestibular surface of the lateral incisor (P < 0.05) and at the midpalatal/midlingual aspect of the first premolar were statistically significant in comparison with the control elements.	The use of a closed-flap surgical technique in association with a codified orthodontic traction system (Easy Cuspid) allowed alignment of palatally impacted canines without damage to the periodontium.
Gharaibeh et al, 2008	Compare the duration of surgery and the patient’s perception of pain after closed and open surgical exposure of unilateral palatally impacted maxillary canines	32/ 16CL 16OP	17.3 ± 4.6/ 28F 4M	Interventional/ Randomized clinical trial	The mean surgical duration for the open-eruption technique was 30.9 ± 10.1 min compared with 37.7 ± 8.4 min for the closed-eruption technique. This difference was statistically significant (p = .006) On the first postoperative day, 6 patients (33%) in the close-eruption group reported severe pain compared with 4 patients (22%) in the open-eruption group. This difference was not statistically significant (p = .123)	The surgical duration was significantly shorter in the open-eruption exposure. Postoperative pain was similar after open- and closed-eruption surgical exposures. However, there was a faster disappearance of severe pain among patients in the closed-eruption groups.
Mummolo, S., et al. 2018	This prospective observational study investigated differences in periodontal health parameters between BIMC and PIMC after surgical orthodontic treatment with open technique and compared the findings with those from contralateral physiologically erupted canines.	9OP	18.50 ± 1.96 5F 4M	Observational/ Prospective Cohort	No signifcant differences were observed in the PIMC group.	The periodontal status of PIMC was not affected by surgical orthodontic treatment with open technique.
Parkin et al, 2013	Investigate differences in the periodontal outcomes of palatally displaced canines exposed with either an open or a closed surgical technique.	71 / 36CL 35OP	14.1 ± 1.6/ 52F 29M	Interventional/ Randomized clinical trial	When the clinical periodontal attachment level values for the unoperated teeth were subtracted from the clinical periodontal attachment level values for the operated teeth, the mean difference between open and closed groups was just 0.1 mm (open, 0.5 mm, SD, 0.8; closed, 0.6 mm, SD, 0.6); this difference was not statistically (independent t test, P = 0.782). The mean attachment loss for 3 of 4 sites was found to be marginally greater in the closed group compared with the open group; however, the difference was not statistically significant. On the midbuccal aspect of the operated canine, in the closed group, 9 subjects (31%) had recession of at least 1 mm (7 subjects had recession of 1 mm, 2 had recession of 2 mm). In the open group, 8 participants (24%) showed recession of a least 1 mm (5 had 1 mm, 3 had 2 mm. No significant difference was found between the 2 groups (chi-square test, P = 0.774)	The exposure and alignment of PDC has a small impact on periodontal health. The magnitude of this impact is not influenced by surgical technique (in terms of open vs closed exposure) and is so small that it is unlikely to influence the prognosis of a tooth in the long term in most patients.
Parkin et al, 2012	Investigate differences in surgical outcomes (time spent in the operating room and 10-day postoperative patient questionnaire findings) between open and closed exposure for palatally displaced maxillary canines	71 / 36CL 35OP	14.1 ± 1.6/ 52F 29M	Interventional/ Randomized clinical trial	The mean operating times for the open and closed techniques were 34.3 ± 11.2 min and 34.3 ± 11.9 min, respectively (p = 0.986) Six of the nine participants reporting that pain was still present after several days were in the open group. Three of the four participants reporting no pain were in the closed group; however, the difference in pain duration between groups was not significant (p = 0.161)	There was no difference in the operating time between the open and closed surgical techniques for palatally displaced maxillary canines. There were no differences in any of the patient-reported outcomes between the 2 surgical procedures. Although most participants reported pain, discomfort, impairment to everyday activies, and the need for regular analgesia after surgical exposure, in most patients this was of short duration and subsided after a few days.
Smailiene et al, 2013	Evaluate the posttreatment status (Radiological, periodontal and intraoral examination – visual assessment of the color and shape of the crown, inclination, position in the dental arch, function) of palatally impacted canines treated applying 2 different surgical methods (open and closed) and to compare it with the status of naturally erupted canines	43 / 21CL 22OP	15.81 ± 3.04/ 35F 8M	Interventional/ Randomized clinical trial	The findings of tooth position, inclination, color, and shape did not differ between groups. No significant differences in the occlusal contacts were found between the groups. The measurements of the PPD did not significantly differ between the groups. The differences in the gingival recession between groups open and closed were not significant.	The posttreatment status of the palatally impacted and the adjacent teeth after the surgical-orthodontic treatment did not significantly differ between the groups treated with 2 different surgical methods, i.e., the open technique with free eruption (open) and the closed flap technique (closed). Both treatment methods can be considered as acceptable for the treatment of palatally impacted canines.
Smailiene et al, 2013	Evaluate post-treatment periodontal status of palatally impacted canines treated by open or closed technique and compare it with naturally erupted canines	43 / 21CL 22OP	15.81 ± 3.04/ 35F 8M	Interventional/ Randomized clinical trial	Measurements of the PPD did not differ significantly between groups open and closed but differed from those in the contralateral quadrants with normally erupted canines. Differences in gingival recession between groups were nonsignificant. Width of keratinized tissue was greater in the open technique group, these measurements did not differ significantly from those in the closed technique group. Bone support did not differ significantly. Mean orthodontic treatment time was 28.41 ± 4.96 in group open and 32.19 ± 11.73 months (p > 0.05) in group closed.	After surgical-orthodontic treatment of palatally impacted canines, either by open surgery with open or by closed technique, there were no significant differences in post-treatment periodontal status of the canines and adjacent teeth. Both treatment methods are acceptable for treatment of the palatally impacted canines; even if the mean time from exposure to eruption / extrusion is somewhat shorter in the open exposure technique. Post-treatment PPD and the level of bone support were not dependent on the patients’ age at the start of treatment, the duration of treatment, or the initial horizontal and vertical localization of impacted canine.
Wisth, P. J., et al. 1976	The aim was to investigate the periodontal status of orthodontically-treated palatally-impacted maxillary canines by clinical and radiographic methods, and to compare it with the status of contralateral canines.	34/ 34OP	17.3 19F 15M	Interventional/ Randomized clinical trial	A comparison of the hygienic condition and the Gingival Index did not reveal any considerable differences between the experimental and the control teeth at the time of examination. A comparison between pocket depth loss of attachment, and distance from the CEJ to the interdental bone showed that the pocket on the distal surface was significantly deeper in the experimental group (p < 0.05). Both de buccal and the palatal surfaces of the experimental teeth displayed significantly greater loss attachment than did the control teeth.	The treated canines displayed significantly more loss of periodontal support on the buccal and palatal surfaces than did the untreated teeth.
Wisth, P. J., et al. 1976	The purpose was to compare the periodontal condition of orthodontically corrected impacted maxillary canines in two groups (open and closed techniques) of patients subjected to different surgical procedures.	56/ 34OP 22CL	15.9	Interventional/ Randomized clinical trial	Oral hygiene and gingival inflammation were approximately the same in both groups. The palatal pocket was deeper on teeth subjected to moderate surgical exposure, and the depth also varied more. The loss of fiber attachment was not significantly different except on the palatal surface, where it was greater after radical exposure and also varied more. The interdental bone height, which was measured on radiographs, varied more after radical than after moderate surgical exposure.	It seems likely that the moderate surgical procedure (closed technique) causes the least periodontal damage. The mean differences were, however, small. If one desires to be able to inspect the position of the tooth regularly, or to reduce the duration of treatment the radical surgical exposure (open technique) can be used.
Zasciurinskiene et al., 2008	To evaluate the impact of surgical-orthodontic (closed technique) treatment and the initial vertical and mesiodistal position of palatally impacted maxillary canines on the periodontal health of impacted canines and adjacent teeth.	32CL	18.2 ± 5.1/ 22F 10M	Observational/Cross-Sectional	A significant increase in pocket depth was found at the canine mesiopalatal point after surgical-orthodontic treatment. Also, a correlation was found between the initial mesiodistal and vertical position of the impacted canine and the posttreatment periodontal status of the impacted canine, the adjacent lateral incisor, and the first premolar.	A combined surgical orthodontic approach in the treatment of impacted maxillary canines produces clinically acceptable periodontal conditions. The average increase in pocket depth was less than 4 mm and clinically unimportant for most patients.

Legend: NA = Not applicable; CL = Closed surgery; OP = Open surgery; F = Female; M = Male; PDC = palatally displaced canine; PPD = periodontal pocket depth.