# Evaluation of the Nasolabbial Angle in Orthodontic Diagnosis: A Systematic Review
## Materials and Methods
### Summary Measures and Approach to Synthesis  
The studies included considered values in degrees of NLA in the following cases: teeth extraction, class II malocclusion, class III malocclusion, rapid palatal expansion (RPE), orthognathic surgery, and non-surgical rhinoplasty with a hyaluronic acid filler. The angular values of NLA are summarized in Table 1A-F, while Table 2A-F summarizes the age and sex data of the patients studied. Total number of patients, their gender, and average age are summarized in Table 3. The summary and explanation of all abbreviations used in all tables and text are summarized in Table 4.  
Figure 2: PRISMA flow diagram showing the study’s screening and selection process. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**(A)**} \\ \hline \hline  & **Article Title** & **Year** & **Author** & **Result** & **NLA Average Value** \\ \hline \multirow{4}{*}{Extractions} & Changes In Soft Tissue Profile & \multicolumn{4}{c}{NLA Increase} \\  & After Orthodontic Treatment & \multirow{2}{*}{2018} & \multirow{2}{*}{[PERSON]} & (4.92\({}^{\circ}\) Average Value) & \\  & With And Without Extraction: & & & In Extractive Group & Not \\  & A Systematic Review & & Et Al. & Compared To & Reported \\  & And Meta-Analysis [3] & & & Non-Extractive Group & \\ \hline \multirow{4}{*}{Extractions} & Post-Orthodontic & \multirow{4}{*}{2019} & \multirow{4}{*}{[PERSON] Et Al.} & \multirow{4}{*}{104.7\({}^{\circ}\)\(\pm\) 18.4\({}^{\circ}\)} \\  & Cephalometric Variations In & & & NLA Increase (6.6\({}^{\circ}\)) & \\  & Binaxillary Protrusion Cases & \multirow{4}{*}{2019} & \multirow{4}{*}{[PERSON] Et Al.} & \multirow{4}{*}{In Extractive Group} & \multirow{4}{*}{104.7\({}^{\circ}\)\(\pm\) 18.4\({}^{\circ}\)} \\  & Managed By Premidor & & & Compared To & \\  & Extraction—A Retrospective & & & Non-Extractive Group & \\  & Study [13] & & & \\ \hline \multirow{4}{*}{Extractions} & Soft Tissue Changes Following & \multirow{4}{*}{2018} & \multirow{4}{*}{[PERSON]} & \multirow{4}{*}{In Extractive Group} & \multirow{4}{*}{Not} \\  & Extraction Vs. Nonextraction & & & In Extractive Group & \\  & Orthodontic Fixed Appliance & & Al. & Compared To & Reported \\  & Treatment: A Systematic & & & Non-Extractive Group & \\  & Review And Meta-Analysis [4] & & & \\ \hline \multirow{4}{*}{Extractions} & Soft Tissue Change In Patients & \multirow{4}{*}{[PERSON] Et Al.} & Higher NLA Increase & \multirow{4}{*}{Not} \\  & With Dentoulveolar Protrusion & & & (3.52\({}^{\circ}\)) & Not \\  & Treated With Maximum & & & Compared To & Reported \\  & Anchorage: A Systematic & & & Traditional & \\  & Review And Meta-Analysis [14] & & & Anchorage (0.68\({}^{\circ}\)) & \\ \hline \multirow{4}{*}{Extractions} & Comparison Of Treatment & \multirow{4}{*}{2018} & \multirow{4}{*}{[PERSON] Et Al.} & Significant & Extr. \\  & Effects Between Four Premier & & NLA Increase & \multirow{4}{*}{109.21\({}^{\circ}\)\(\pm\) 11.72\({}^{\circ}\)} \\  & Extraction And Total Arch & & & NLA Increase & \\  & Distalization Using The & & In Both Study Groups & \\  & Modified C-Palatal Plate [2] & & & \\ \hline \multirow{4}{*}{Extractions} & Soft Tissue Facial Profile & \multirow{4}{*}{2019} & \multirow{4}{*}{[PERSON] Et Al.} & \multirow{4}{*}{ \begin{tabular}{c} Significant \\ NLA Increase \\ In Both Study Groups \\ \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{c} Estr. \\ 109.21\({}^{\circ}\)\(\pm\) 11.72\({}^{\circ}\)\(\pm\) 11.72\({}^{\circ}\) \\ \(\pm\) 11.55\({}^{\circ}\)\({}^{\circ}\) \\ \end{tabular}  } \\  & Soft Tissue Facial Profile & \multirow{4}{*}{2017} & \multirow{4}{*}{[PERSON] Et Al.} & \multirow{4}{*}{ \begin{tabular}{c} Significant \\ NLA Increase \\ In Both Study Groups \\ \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{c} Estr. \\ 109.21\({}^{\circ}\)\(\pm\) 11.72\({}^{\circ}\)\(\pm\) 11.55\({}^{\circ}\) \\ \(\pm\) 11.55\({}^{\circ}\) \\ \end{tabular}  } \\  & Changes After Orthodontic & & & & \\  & Treatment With Or Without & \multirow{4}{*}{2019} & \multirow{4}{*}{