The manuscript addresses a very interesting and relevant theme. However, some corrections are necessary.
Abstract- from the title, in the abstract and throughout the text, the authors present bruxism as a parafunction. This is a concept that is considered outdated. I suggest that all the work be based on the classification of the 2018 international consensus (Lobbezoo et al., 2018). The methodology described in the abstract lacks information: how many participants? what age group? What are the collection instruments? The authors reported that linear regression analysis was performed and did not present the Confidence Interval values nor did p values be presented in the results. I propose that the entire text of the Abstract be rewritten.
Introduction - the theoretical framework used is old. Checking the bibliographic references, it is observed that there are references from the 90's, works with more than ten years of publication. The concept of bruxism, for example, was based on a 2010 reference. Conceptualizing bruxism as a parafunctional habit is in disuse. Please see the 2018 international consensus.
Methodology - the authors reported that an important database was used. All information was based on a parent's report. Bruxism reported by parents or self-reported is called possible bruxism in the criteria of international consensus. Please update the terminology. It is not clear what the age range of the participants was. Would it be the entire database of families with Rett syndrome? Why wasn't there a control group of non-syndromic children?
Discussion - the whole discussion is based on concepts of parafunction. There are comparisons with studies of other syndromes. Rett's syndrome is rare. This is a fact. However, the discussion is superficial. The jobs used to compare results need to be updated.
This is a cross-sectional study and has its value. However, the findings cannot be used for cause and effect analysis. This is an important limitation to be commented on.

The authors worked hard on the manuscript. Almost all of my questions have been answered. I emphasize that it is necessary for the authors to discriminate which type of bruxism they refer to: would it be sleep bruxism or awake bruxism? Throughout the manuscript the authors used the term bruxism. It is important to distinguish the type of bruxism studied.