Table 1 Search strategies for different databases

Pubmed

((orthodontics[MeSH Terms]) AND ((maxillary expansion) OR palatal expansion technique[MeSH Terms])) AND (face[Title/Abstract] OR mouth[Title/Abstract] OR lip[Title/Abstract] OR nose[Title/Abstract] OR nasal[Title/Abstract] OR naso*[Title/Abstract] OR alar[Title/Abstract] OR soft tissue*[Title/Abstract])

Embase

#1 ‘orthodontics’/exp.

#2 ‘palatal expansion technique’/exp.

#3 ‘maxillary expansion’

#4 ‘soft tissue’:ab,ti

#5 face:ab,ti OR mouth:ab,ti OR lip:ab,ti OR nose:ab,ti OR nasal:ab,ti OR naso*:ab,ti OR alar:ab,ti

#6 #2 OR #3

#7 #4 OR #5

#8 #1 AND #6 AND #7

Crochrane

#1 MeSH descriptor: [Orthodontics] explode all trees

#2 MeSH descriptor: [Palatal Expansion Technique] explode all trees

#3 face or mouth or lip or nose or nasal or naso* or alar or ‘soft tissue*’:ti,ab,kw (Word variations have been searched)

#4 ‘maxillary expansion’ (Word variations have been searched)

#5 #2 OR #4 #6 #1 AND #3 AND #5

Ovid

1. exp. orthodontics/

2. exp. palatal expansion technique/

3. maxillary expansion.af.

4. 2 or 3

5. (face or mouth or lip or nose or nasal or naso* or alar or soft tissue*).af.

6. 1 and 4 and 5

MEDLINE Complete (EBSCOhost)

AB (face or mouth or lip or nose or nasal or naso* or alar or ‘soft tissue*’) AND AB orthodontic AND AB ((maxillary expansion) OR (palatal expansion))

CINAHL (EBSCOhost)

same as MEDLINE Complete

SCOPUS

(TITLE-ABS-KEY(face OR mouth OR lip OR nose OR nasal OR naso* OR alar OR “soft tissue*”) AND TITLE-ABS-KEY(“maxillary expansion” OR “palatal expansion”) AND TITLE-ABS-KEY(orthodontic))

Sciencedirect

TITLE-ABSTR-KEY(face OR mouth OR lip OR nose OR nasal OR naso* OR alar OR “soft tissue*”) and TITLE-ABSTR-KEY((orthodontic AND (“maxillary expansion” OR “palatal expansion”)))