Penelitian ini bertujuan untuk mengetahui pengaruh waktu paparan gel theobromine terhadap kekerasan permukaan email setelah demineralisasi dengan asam sitrat 1%. Spesimen email direndam asam sitrat 1% selama 2,5 menit lalu kemudian dipapar oleh gel theobromine 200 mg/l selama 16, 48 dan 96 menit. Nilai kekerasan email diuji menggunakan Knoop Microhardness Tester Shimadzu, Japan. Uji Wilcoxon dan Mann-Whitney menunjukkan bahwa terjadi penurunan nilai kekerasan email secara bermakna (p<0,05) setelah demineralisasi dengan asam sitrat 1% sebesar 35%-39%. Gel theobromine 200 mg/l dapat meningkatkan kekerasan email secara bermakna (p<0,05) yang telah didemineralisasi oleh asam sitrat 1%.

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The aim of this study was to investigate the effect of different exposure time of theobromine gel on enamel microhardness after demineralization with 1% citric acid. Specimens were immersed in 1% citric acid solution for 2.5 minutes and then were exposed to theobromine gel 200 mg/l for 16, 48 and 96 minutes. Enamel microhardness value was tested using Knoop Microhardness Tester Shimadzu Japan. Wilcoxon and Mann-Whitney test showed significant reduction (p<0,05) of microhardness value for all specimens after demineralization with 1% citric acid about 35-39%. Theobromine gel could increase enamel microhardness significantly (p<0,05) after deminerlization with 1% citric acid.