Latar Belakang: Beberapa penelitian menyatakan bahwa perawatan ortodonti non ekstraksi pada kasus borderline menyebabkan perubahan inklinasi insisif atas dan bawah yang dapat mempengaruhi profil jaringan lunak pasien. Tujuan: Mengetahui korelasi perubahan inklinasi insisif atas dan bawah terhadap perubahan besar sudut Nasolabial dan sudut Mentolabial sebelum dan sesudah perawatan ortodonti non ekstraksi pada maloklusi kelas I. Metode: 26 sampel penelitian sefalometri lateral sebelum dan sesudah perawatan ortodonti non ekstraksi dilakukan penapakan dan pengukuran sudut I-SN, IMPA, sudut Nasolabial, dan sudut Mentolabial. Uji statistik menggunakan uji non parametrik Wilcoxon dan uji korelasi Spearman. Hasil: Tidak ada perbedaan yang bermakna pada sudut I-SN dan sudut Nasolabial sebelum dan sesudah perawatan namun, terdapat perbedaan yang bermakna pada IMPA dan sudut Mentolabial sebelum dan sesudah perawatan ortodonti. Uji korelasi menunjukkan terdapat korelasi negatif yang sangat lemah antara perubahan sudut I-SN terhadap perubahan sudut Nasolabial serta antara perubahan IMPA terhadap perubahan sudut Mentolabial. Kesimpulan: Penurunan sudut I-SN disertai peningkatan sudut Nasolabial, meskipun korelasinya sangat lemah. Peningkatan sudut IMPA disertai peningkatan sudut Mentolabial, juga mempunyai korelasi yang sangat lemah.

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Background: Some studies showed that non-extraction orthodontic treatment in borderline cases led to upper and lower incisor inclination changes that affected patient’s soft tissue profile.

Objective: To find out the correlation between upper and lower incisor inclination changes towards Nasolabial angle and Mentolabial angle value changes before and after non-extraction orthodontic treatment in class I malocclusion.

Method: There were 26 samples before and after lateral cephalometric of orthodontic non extraction treatment with measurement of I-SN, IMP, Nasolabial, and Mentolabial angles. Statistical test was done using non parametric Wilcoxon test and Spearman correlation test.

Result: No significant difference in I-SN angle and Nasolabial angle before and after orthodontic treatment. However, there was a significant difference in IMP and Mentolabial angles before and after orthodontic treatment. Correlation test showed a very weak negative correlation between I-SN and IMP angle changes towards Nasolabial and Mentolabial angle changes.

Conclusion: The decrease of I-SN angle is followed by the increase of Nasolabial angle, although the correlation is very weak. The increase of IMP angle is followed by the increase of Mentolabial angle, which also has a very weak correlation.