## 2 Materials and Methods
### Assessment of Methodological Quality and Risk of Bias  
Methodological quality assessment and risk of bias analysis were performed by two investigators (LMF and COL) in the included studies. The authors utilized the Quality Assessment Tool for Before-and-After Studies ([[https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools](https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools)]([https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools](https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools)) (accessed on 24 April 2023)) to evaluate the study. This checklist was developed for medical articles, but it has already been used by other authors to assess the methodological quality and the risk of bias in dentistry studies [21; 22] with some adaptations. Although this tool includes 12 items, as a way of adapting to the types of studies included in this review, three items were removed and the remaining nine were used: (1) if the question or purpose of the study was clearly stated; (2) if the eligibility criteria were pre-specified and clearly described; (3) if the participants were representative of the population; (4) if all eligible participants who met the inclusion criteria were included; (5) if \begin{table}
\begin{tabular}{c c c c} \hline
**Database** & & & **Search Strategy** \\ \hline
**Cochrane** & \#1 & MeSH descriptor: [Bone Density] explode all trees & 5450 \\  & \#2 & (bone density):ti,ab,kw OR (bone mineral density):ti,ab,kw (Word variations have been searched) & 14,225 \\  & \#3 & (density sutur\({}^{\star}\)):ti,ab,kw OR (midpalatal suture):ti,ab,kw OR (suture maxillary):ti,ab,kw (Word variations have been searched) & 331 \\  & \#4 & Hounsfield units & 327 \\  & \#5 & \#1 or \#2 or \#3 or \#4 & 14,763 \\  & \#6 & MeSH descriptor: [Palatal Expansion Technique] explode all trees & 267 \\  & \#7 & (expansion technique palatal):ti,ab,kw OR (expansion maxillary):ti,ab,kw OR (palatal expansion):ti,ab,kw OR (RME):ti,ab,kw (Word variations have been searched) & 596 \\  & \#8 & \#6 or \#7 & 596 \\  & \#9 & MeSH descriptor: [Cone-Beam Computed Tomography] explode all trees & 467 \\  & \#10 & (“cone beam computed tomography”):ti,ab,kw OR (CBCT):ti,ab,kw (Word variations have been searched) & 1932 \\  & \#11 & (volume CT):ti,ab,kw (Word variations have been searched) & 8326 \\  & \#12 & MeSH descriptor: [Tomography, X-Ray Computed] explode all trees & 7048 \\  & \#13 & (X-Ray Computed tomography):ti,ab,kw OR (X Ray tomography computed):ti,ab,kw OR (tomography X Ray computed):ti,ab,kw OR (computed tomography):ti,ab,kw (Word variations have been searched) & 24,245 \\  & \#14 & MeSH descriptor: [Imaging, Three-Dimensional] this term only & 1353 \\  & \#15 & (Three-dimensional imaging):ti,ab,kw OR (Three-dimensional images):ti,ab,kw (Word variations have been searched) & 3167 \\  & \#16 & \#9 or \#10 or \#11 or \#12 or \#13 or \#14 or \#15 & 32,917 \\  & \#17 & \#5 and \#8 and \#16 & \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._the sample size was large enough to provide confidence in the results; (6) if the intervention was clearly described and consistently performed; (7) if the measurement results were pre-specified, clearly defined, valid, reliable, and consistently evaluated; (8) if the loss to follow-up after initiation of treatment was 20% or less and if these losses were accounted for in the analysis; and (9) if statistical methods were performed to assess changes in pre- and post-intervention measures and if a \(p\)-value was provided. For item 5, a study that presents a sample calculation or analysis of the power a posteriori, or if it presents a sample greater than 50 participants, is considered adequate. When checking the criteria for each item, responses of 'Yes', 'No', 'CD' (cannot determine), 'NA' (not applicable), or 'NR' (not reported) were assigned.