Latar Belakang: Sindroma Down merupakan kelainan genetik yang disebabkan oleh terjadinya trisomi pada kromosom 21.  Penyandang sindroma Down memiliki karakteristik fisik dan kondisi sistemik tertentu. Hal ini berhubungan dengan kondisi rongga mulutnya, terutama jaringan periodontal (gingiva) serta kebersihan gigi dan mulut. Tujuan: Penelitian ini bertujuan untuk mengetahui distribusi frekuensi gingivitis dan OHIS (Oral Hygiene Index-Simplified) pada penyandang sindroma Down usia 14 tahun ke atas di SLB tipe C di Jakarta. Metode: Penelitian ini merupakan studi deskriptif potong lintang. Subjek penelitian adalah 174 penyandang sindroma Down usia 14 tahun ke atas yang bersekolah di SLB tipe C di Jakarta. Gingivitis diukur menggunakan Indeks Gingiva oleh Loe dan Sillness, sementara kebersihan gigi dan mulut diukur menggunakan OHIS oleh Greene dan Vermillon. Hasil: Hasil dari penelitian menunjukkan distribusi frekuensi gingivitis sebagai berikut; 3,45% bebas gingivitis, 47,13% gingivitis ringan, 40,80% gingivitis sedang, dan 8,63% gingivitis berat. Sementara, untuk distribusi frekuensi OHIS adalah sebagai berikut; 28,16% memiliki OHIS baik, 49,43% memiliki OHIS sedang, dan 22,41% memiliki OHIS buruk. Kesimpulan: Penyandang sindroma Down memiliki distribusi frekuensi gingivitis yang dominan pada gingivitis ringan dan sedang, sementara mayoritas memiliki OHIS sedang.

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Background: Down syndrome is a genetic disorder caused by trisomy in chromosome 21. Individuals with Down syndrome have specific physical characteristics and systemic conditions. This may relate to their oral condition, such as periodontal tissues (gingiva) as well as their oral hygiene. Objective: The aim of this study is to know the frequency distribution of gingivitis and OHIS (Oral Hygiene Index-Simplified) in 174 individuals with Down syndrome aged 14 and above in SLB type C in Jakarta. Method: This study used a cross-sectional descriptive method. Research subjects were 174 individuals with Down syndrome aged 14 and above who went to school in SLB type C in Jakarta. Gingivitis was measured using Gingival Index by Loe and Sillness, while oral hygiene was measured using OHIS by Greene and Vermillon. Result: The result of this study showed a frequency distribution of gingivitis as follows; 3.45% were free of gingivitis, 47.13% had mild gingivitis, 40.80% had moderate gingivitis, and 8.63% had severe gingivitis. Frequency distribution of OHIS were as follows; 28.16% had good OHIS, 49.43% had fair OHIS, and 22.41% had poor OHIS. Conclusion: Individuals with Down syndrome had frequency distribution of gingivitis mainly in mild and moderate category, while the majority the subjects had fair OHIS.