| Articles |
Reason for exclusion |
| Al Yami et al. [23] |
Stability after orthodontic treatment, published before year 2005 |
| Booth et al. [24] |
Wrong comparison (time point when retainer was lost was not stated) |
| Danz et al. [25] |
Wrong patient groups (data not extractable for different types of retainers) |
| Devreese et al. [26] |
Wrong outcome (case-series, no complications reported) |
| Freitas et al. [27] |
Wrong intervention and comparison (compares other interventions) |
| Johnsson et al. [28] |
Wrong intervention and comparison (compares two clinics) |
| Kuijpers et al. [29] |
Wrong outcome (studies occlusal wear) |
| Lagerström et al. [30] |
Wrong comparison (time point when retainer was lost was not stated) |
| Lagravere et al. [31] |
Wrong intervention (studies rapid maxillary expansion) |
| Lang et al. [32] |
Stability after orthodontic treatment, published before year 2005 |
| Littlewood et al. [3] |
Same data as in Littlewood et al., 2006a |
| Maia et al. [33] |
Wrong outcome (case-series, no complications reported) |
| McNamara et al. [34] |
Wrong intervention (studies rapid maxillary expansion vs. no orthodontics) |
| Millet et al. [35] |
Wrong Intervention studied in systematic review |
| Morton and Pancherz [36] |
Wrong outcome (case-series, no complications reported) |
| Myser et al. [37] |
Case-series with too few patients (included 25 out of 66 eligible) |
| Renkema et al. [38] |
Data not extractable |
| Renkema et al. [39] |
Wrong outcome (case-series does not study complications) |
| Renkema et al. [40] |
Wrong intervention (does not study retainer) |
| Renkema et al. [41] |
Wrong intervention (does not study retainer) |
| Sari et al. [42] |
Wrong intervention (too short follow-up) |
| SBU [6] |
Data presented in Bondemark et al., 2007 |
| Tofeldt et al. [43] |
Wrong intervention and comparison (compares two clinics) |
