Review: Effect of biomechanical properties of perioral soft tissues on lip response to simulated protraction of upper front teeth.

Thank you for giving me the opportunity to review this innovative and well written paper. I have some minor concerns and comments that could potentially improve the paper, but overall I congratulate the authors on a very nice piece of work.

Minor revision

Aims and objectives (Abstract and Introduction): The first aim (“to evaluate the 3D lip changes induced by the simulated incisor protraction using 3D stereophotogrammetry”) is not reported as clearly in the text as the second objective. The results of this first aim are reported in the text, but the values are not reported in any table, and the changes were not tested statistically, by contrast with the second aim, for which the results are described much more extensively in tables and text and were statistically tested. Emphasizing the results of the first aim by adding a table and possibly statistics would improve the paper and might also reduce the wordy description of the results on page 9.

Abstract line 37: “approximately 50% of the intended advancement”: “intended” might be misleading and could be rephrased (advancement related to the stent?)

Statistics (Methods/Results): Is it worth reporting the results of the Pearson's correlation coefficients, as a much more powerful mixed model analysis was used to investigate the relationship between soft-tissue displacement and soft-tissue properties? Likewise, in the abstract (results paragraph), the results of the multivariate analysis are not reported, and could be reported instead of the Pearson's correlation coefficients.

Results/Demographic groups: in the Demographic characteristics of the Results section (page 8), “Other” refers to individuals of Middle Eastern and Pasifika, NOT Māori, while in the Multivariate analyses of the Results section (page 10), “Others” refers to Middle Eastern, Pasifika AND Māori. Could this be modified for consistency?

Table 1: Are those results with or without stent?