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Table 1. Characteristics of included studies.

From: Duration of orthodontic treatment with fixed appliances in adolescents and adults: a systematic review with meta-analysis

Study Design; setting; countrya Patients (M/F); mean ageb Malocclusion Treatment Severity Appliance Ex
Bhattarai 2011 [30] rNRS; Uni; NP AD: 134 (NR); 13.6
ADU: 46 (NR); 23.1
No impactions, 2-phase Tx, or non-compliant patients; all permanent teeth except M3 Full Tx NR Roth FA 0.018” (loops, elastics; HG) NR
Dyer 1991 [1] rNRS; Pract; US AD: 30 (0/30); 12.5
ADU: 26 (0/26); 27.6
Cl. II/1; all permanent teeth except M3 Full Tx ≥ ½ Cl. II MR SE FA 0.022” (elastics, HG, sliding jigs) 4xPM
Furquim 2018 [31] rNRS; Pract; BR AD: 23 (10/13); 11.8
ADU: 16 (7/9); 22.4
Cl. II Full Tx NR FA and MPA NR
Harris 1990 [32] rNRS; Pract; US ADc: 29 (0/29); 12.5
ADUc: 30 (0/30); 27.9
Cl. II/1; all permanent teeth except M3 Full Tx ≥ ½ Cl. II MR FA (SDFET) 4xPM
Iancu 2018 [33] rNRS; Uni; IT AD: 19 (8/11); 13.8
ADU: 3 (2/1); 23.7
PDC PDC alignment NR OSE; FA 0.022 (TPA, CAN) NR
Jiang 2017 [34] pNRS; Uni; US AD: 10 (6/4); 14.7
ADU: 8 (1/7); 25.1
Need for Mx canine retraction Canine retraction NR FA 0.019” (T-loops 124cN; TPA) 2x Mx PM
Loke 2012 [35] rNRS; Pract; MY ADc: 716 (NR); NR
ADUc: 156 (NR); NR
No syndromes, CLP, or only RFA; Cl. I (28%), II (57%), III (15%); impactions (7%) Full Tx NR FA ± Mx removable appliance, functional appliance, or surgery Ex (74%)
Nienkemper 2014 [36] rNRS; Uni;
DE
AD: 37 (17/20); 12.9
ADU: 14 (4/10); 30.9
≥ ¼ bilateral Cl. II MR or anterior Mx crowding Full Tx ≥ ¼ Cl. II MR MI-distalizer NR
Robb 1998 [37] rNRS; Pract; US ADd: 40 (15/25); 12.9
ADUd: 32 (12/20); 31.3
Cl. I (94%) or II (6%) Full Tx NR FA 4xPM
Sachdeva 2012 [38] rNRS; Pract; US AD: 1861 (NR); NR
ADU: 979 (NR); NR
Cl. I, II, or III Full Tx Mean PAR = 25.5 FA NR
Shim 2011 [39] rNRS; Pract; KR ADc: 70 (35/35); NR
ADUc: 70 (35/35); NR
No root resorptions, root-fillings, or trauma Full Tx NR SE FA Ex PM1 (55%)
  1. rNRS retrospective non-randomized study, pNRS prospective non-randomized study, Uni university clinic, Pract private practice, AD adolescent, ADU adult; NR, not reported, Tx treatment, M3 3rd molars, Cl. angle’s class, CLP cleft lip and palate, RFA removable functional appliance, MR molar relationship, Mx maxillary, PDC palatally displaced canine, PAR Peer Assessment Rating, FA fixed appliance, HG headgear, SE standard edgewise, MPA mandibular protraction appliance, SDFET sequential directional force edgewise technique, MI miniscrew implant, OSE open surgical exposure, TPA transpalatal arch, CAN cantilever, PM premolar, Ex extraction of permanent teeth
  2. aGiven with the country’s ISO 3166 alpha-2 code
  3. bWith 18 years of age taken as cut-off for adults, except if otherwise noted
  4. c20 years taken as cut-off for adults
  5. d21 years taken as cut-off for adults.