Fig 2. Theoretical model of the different paths that were tested between the independent variables and the association with the upper intermolar distance.

References: a. [20, 21, 34, 35, 36] b. [22–24] c. [25, 37, 38] d. [39, 40] e. [40, 41] f. [15] g. [29] h. [15, 29] i. [31].