Table 2 Search strategy

Database

PubMed

((((((((("E space preservation"[All Fields] OR "Leeway space"[All Fields]) OR "E space"[All Fields]) OR "arch length preservation"[All Fields]) OR "nance lingual arch"[All Fields]) OR "lingual arch"[All Fields]) OR "lingual holding arch"[All Fields]) OR "lip bumper"[All Fields]) OR "Schwarz appliance"[All Fields]) AND ("dentition, mixed"[MeSH Terms] OR ("dentition"[All Fields] AND "mixed"[All Fields]) OR "mixed dentition"[All Fields] OR ("mixed"[All Fields] AND "dentition"[All Fields]))) OR ("Mandibular second molar impaction"[All Fields] OR (("mandible"[MeSH Terms] OR "mandible"[All Fields] OR "mandibular"[All Fields]) AND second[All Fields] AND ("molar"[MeSH Terms] OR "molar"[All Fields]) AND ("tooth eruption"[MeSH Terms] OR ("tooth"[All Fields] AND "eruption"[All Fields]) OR "tooth eruption"[All Fields] AND difficulty[All Fields])) OR (("mandible"[MeSH Terms] OR "mandible"[All Fields] OR "mandibular"[All Fields]) AND second[All Fields] AND ("molar"[MeSH Terms] OR "molar"[All Fields]) AND ectopic[All Fields] AND "eruption"[All Fields]))

Cochrane registry, CENTRAL Clinicaltrails.gov, Google scholar, journal database (Elsevier, Wiley, Oxford Academic, SAGE journals)

"Mixed dentition", “transitional dentition”, “Leeway space” "E space", "lingual holding arch", “Nance holding arch”, "lip bumper", "Schwarz appliance", "mandibular second molar impaction", “mandibular second molar eruption disturbances”, “mandibular second molar eruption difficulties”

Filters

None

Journals searched through journal database

European Journal of Orthodontics, Journal of Orthodontics, Journal of Clinical Orthodontics, Seminars in Orthodontics, American Journal of Orthodontics & Dentofacial Orthopedics, Angle Orthodontist, and Orthodontics & Craniofacial Research