Author, year Country Study design Number
of patients (n)
With
drawals
-
dropouts
Result Comments
Intervention
Fixed retainer
Control
No retainer
Artun, [14] Norway CT n=108 Group 1: n= 31 Group 2: n=18 Group 3: n=14 (Group 4: n=20) Group 5: n= 25 ? a Groups 1 and 2 Interproximal:
Mean: 0.37 (sd 0.39)   Lingual:
Mean: 0.22 (sd 0.29)  
Group 5 Interproximal:
Mean: 0.38 (sd 0.36)
ns. Lingual:
Mean: 0.14 (sd 0.20)
ns.  
Group 1=  Mandibular cuspid retainer .032 spiral wire.
Group 2=  Mandibular cuspid retainer .032 plain wire.
Group 3=  Maxillary .0195 flexible spiral wire retainer.
Group 4=  Maxillary retainer plate
Group 5=  No retainer. Cuspid retainer = bonded only to cuspids.
3-3- retainer = bonded to each tooth.
a Withdrawals and drop-outs not explicitly stated. CT = non-randomised, controlled study. ns = not significant
Table 13: Fixed orthodontic retainer versus no retainer – Calculus (alphabetically, according to study design).