Latar Belakang: Residu radikal bebas pasca perawatan internal bleaching dapat mengganggu proses polimerisasi resin komposit. Akibatnya, terjadi penurunan kekuatan ikatan restorasi. Antioksidan ekstrak teh hijau dapat digunakan untuk menghilangkan radikal bebas pasca bleaching dan meningkatkan shear bond strength resin komposit. Tujuan: mengetahui perbedaan shear bond strength resin komposit pada dentin pasca internal bleaching dengan dan tanpa aplikasi ekstrak teh hijau pada konsentrasi yang berbeda selama 2 menit. Metode: 25 gigi premolar, dipotong dalam arah mesiodistal, dan dibagi menjadi 5 kelompok: Kelompok 1 dentin normal, Kelompok 2 dentin pasca bleaching, Kelompok 3 dentin 2 minggu pasca bleaching, Kelompok 4  dentin pasca bleaching dengan teh hijau 10% 2 menit, dan Kelompok 5 dentin pasca bleaching dengan aplikasi teh hijau 35% 2 menit. Semua kelompok diaplikasikan restorasi resin komposit. Uji shear bond strength menggunakan Universal Testing Machine. Analisis statistik menggunakan one-way ANOVA dan Uji Post Hoc Bonferroni. Hasil: Uji Post Hoc Bonferroni menunjukkan perbedaan bermakna antara kelompok 1 dan 4, kelompok 2 dan 5, serta kelompok 4 dan 5. Kesimpulan: Aplikasi antioksidan ekstrak teh hijau 35% selama 2 menit lebih tinggi dalam meningkatkan shear bond strength resin komposit dibandingkan dengan aplikasi ekstrak teh hijau 10% selama 2 menit pada dentin pasca internal bleaching menggunakan hidrogen peroksida 35%.

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Introduction: Internal bleaching treatment could leave free radicals in the dentinal tubules. It can interfere with the polymerization process of the composite resin. Antioxidants from green tea extract can remove the free radicals after bleaching and increase the shear bond strength of composite resin.

Objective: To determine the shear bond strength of composite resin on dentin after internal bleaching with and without green tea extract application at different concentrations in 2 minutes.

Methods: 25 premolars were cut in mesiodistal direction and divided into five groups: Group 1 normal dentin, Group 2 bleached dentin, Group 3 bleached dentin, Group 4 10% green tea application in 2 minutes, and Group 5 35% green tea application in 2 minutes. All groups were restored with composite resin. All specimens' shear bond strength was tested with the Universal Testing Machine. The data were analyzed with one-way ANOVA and Bonferroni Post Hoc Test.

Results: Post Hoc Bonferroni test showed that there were statistical differences  in groups 1 and 2, groups 1 and 4, groups 2 and 5, and groups 4 and 5.

Conclusion: 35% green tea extract is more effective than 10% green tea extract as an antioxidant for increasing the shear bond strength of composite resin after internal bleaching.