TABLE 2.

Methodological characteristics of included studies

Question	Kahl 1990	Kahl 1995	Kahl‐Nieke 1994	Kahl‐Nieke 1995	Kahl‐Nieke 1998; 1999	Liu 2014	Strobl 1999	Zhao 2014
Was the study prospective?	No	No	No	No	No	No	Yes	No
Were participants age described?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Were participants sex described?	No	No	Yes	No	Yes	Yes	Yes	Yes
Were participants maturation stage described?	No	No	No	No	No	No	No	No
Was the fracture type adequately described?	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes
Was FA (functional appliance) treatment described?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Was selection of patients based on any factor that could influence the outcome (fracture type, malocclusion, compliance, missed appointments, breakages, attrition)?	Unclear	Yes	Yes	Unclear	Probably yes	Unclear	Yes	Unclear
Were outcomes patients measured blindly?	No	No	No	No	No	No	No	No
Was the adequate sample? (25 patients per group)	No	No	No	No	No	Yes	Yes	Yes
Was there adequate follow‐up (at least 1 year)?	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes
Were FA/ CTR groups clearly defined?	Yes	—	—	—	Yes	—	—	—
Were FA/ CTR patients treated/observed at the same place/time?	Unclear	—	—	—	Unclear	—	—	—
Were FA/ CTR patients matched for baseline age?	No	—	—	—	Yes	—	—	—
Were FA/ CTR patients matched for baseline sex?	NR	—	—	—	Yes	—	—	—
Were FA/ CTR patients matched for baseline malocclusion?	NR	—	—	—	NR	—	—	—
Were FA/ CTR patients matched for fracture type?	No	—	—	—	Unclear	—	—	—
Was the use of other treatments the same among FA/ CTR patients?	Yes	—	—	—	Yes	—	—	—
Was the observation period similar for FA/ CTR patients?	No	—	—	—	No	—	—	—
Were FA/CTR patients measured exactly the same way?	Yes	—	—	—	Yes	—	—	—

CTR Control group.

Abbreviations: FA functional appliance; NR not reported.