Figure 1. | PRISMA flow diagram demonstrating the results of the systematic literature search. |

The electronic search resulted in 1833 entries. No article was included as the result of hand-searching. Five hundred and fifty articles were excluded, because they had been retrieved in more than one search. A total of 64 abstracts were reviewed. Full-text analysis included 15 articles. Finally, five human studies were included in the present systematic review comprising one comparative study and four noncomparative studies. |