Outcome variable Number of studies and study design Study limitations Consistency Directness Precision Publication bias

 

Magnitude of
effect

 Absolute effect I=fixed retainer
C=no retainer 		Quality of evidence
GRADE
  Periodontal outcomes   3 Cohort     Serious limitations
(-1)c 		  No inconsistency   Serious indirectness
(-1)b		   Serious imprecision
(-1)a 		  Unlikely   Not relevant   Not applicablef   ⊕⃝⃝⃝
  Dental Caries   1 Cohort     Serious limitations
(-1)c 		  No inconsistency   Serious indirectness
(-1)b		   Serious imprecision
(-1)e 		  Unlikely   Not relevant   I=0
C=0 		  ⊕⃝⃝⃝
  Dental plaque     3 Cohort   Serious limitations
(-1)c		   No inconsistency   Serious indirectness
(-1)d 		  Serious imprecision
(-1)a 		  Unlikely   Large effect
(+1)		   Not applicablef   ⊕⃝⃝⃝
  Calculus     1 Cohort     Serious limitations
(-1)c		   No inconsistency   Serious indirectness
(-1)b		   Serious imprecision
(-1)e		   Unlikely   Not relevant   Lingual:
I=0.22
C=0.14		   ⊕⃝⃝⃝
  Gingivitis     3 Cohort     Serious limitations
(-1)c		   No inconsistency   Serious indirectness
(-1)b 		  Serious imprecision
(-1)e		   Unlikely   Not relevant   Not applicablef   ⊕⃝⃝⃝
⊕⊕⊕⊕= high quality of evidence, ⊕⊕⊕⃝ = moderate quality of evidence, ⊕⊕⃝⃝ = Low quality of evidence, ⊕⃝⃝⃝ = Very low quality of evidence.[10] a Small groups in some studies, and no 95%CI presented. b Patient characteristics not clearly described. c Unclear patient selection. No blinding. d Patients from a different setting. e No CI 95% presented. f No pooled effect estimates, due to different outcomes across the studies.
Table 17: Summary of Findings - Fixed retainer versus no retainer.