A literature search was conducted using PubMed, Medline, Google Scholar, EMBASE, CNKI, Web of Science, and the Cochrane Collaboration, identifying English- and non-English-language articles reporting on interalar width, inner canthal width, and maxillary anterior tooth width. 
PubMed
A literature search was conducted using PubMed, Medline, Google Scholar, EMBASE, CNKI, Web of Science, and the Cochrane Collaboration, identifying English- and non-English-language articles reporting on interalar width, inner canthal width, and maxillary anterior tooth width. 
Medline
A literature search was conducted using PubMed, Medline, Google Scholar, EMBASE, CNKI, Web of Science, and the Cochrane Collaboration, identifying English- and non-English-language articles reporting on interalar width, inner canthal width, and maxillary anterior tooth width. 
Google Scholar
A literature search was conducted using PubMed, Medline, Google Scholar, EMBASE, CNKI, Web of Science, and the Cochrane Collaboration, identifying English- and non-English-language articles reporting on interalar width, inner canthal width, and maxillary anterior tooth width. 
EMBASE
A literature search was conducted using PubMed, Medline, Google Scholar, EMBASE, CNKI, Web of Science, and the Cochrane Collaboration, identifying English- and non-English-language articles reporting on interalar width, inner canthal width, and maxillary anterior tooth width. 
CNKI
A literature search was conducted using PubMed, Medline, Google Scholar, EMBASE, CNKI, Web of Science, and the Cochrane Collaboration, identifying English- and non-English-language articles reporting on interalar width, inner canthal width, and maxillary anterior tooth width. 
Web of Science
A literature search was conducted using PubMed, Medline, Google Scholar, EMBASE, CNKI, Web of Science, and the Cochrane Collaboration, identifying English- and non-English-language articles reporting on interalar width, inner canthal width, and maxillary anterior tooth width. 
Cochrane Collaboration
Using a meta-analysis software program, data extracted from each selected study were statistically combined using the random-effects model. 
meta-analysis software program