Introduction: The number of patients who seek orthodontic treatment that may have a history of tooth bleaching is increasing over the time. Bleaching may influence the decrease of the bond strength of orthodontic brackets. Objective: To determine and prove the effect of mangosteen peel (MP) extract to reverse the reduced shear bond strength (SBS) of orthodontic brackets after bleaching. Methods: A total of 150 maxillary first premolar teeth were randomly divided into 6 experimental groups as follow (n=25): negative-control (N: no bleaching), positive-control (P: bleaching + no treatment), and the treatment groups (bleaching + 10% sodium ascorbate (SA), 10% (MP-10), 20% (MP-20) and 40% (MP-40) MP extract gel). After treatment, the brackets were bonded with the resin-modified glass ionomer cement, SBS testing was performed using universal testing machine, and the adhesive remnant index (ARI) was examined using stereoscopic microscope after debonding. The SBS data were analyzed by analysis of variance (Anova) and the Tukey test. For the ARI, the Kruskal-Wallis test was performed. Result:There was significant SBS difference (p< 0.001) between various groups. The group without bleaching showed significantly higher SBS (8.19 ± 2.26 MPa) compared to others, while SBS in the group treated with 40% MP gel was significantly higher (7.93 ± 1.92 MPa) than other groups treated with antioxidants. The failure of orthodontic brackets bonded after bleaching and treatment using MP extract occurred at the enamel-adhesive interface. Conclusion: The application of MP extract as an antioxidant after bleaching was effective in reversing the reduced shear bond strength of orthodontic brackets after bleaching.

ABSTRAKDunia kedokteran gigi banyak menggunakan logam pada pembedahan maxillofacial, cardiovascular, dan sebagai material dental. Logam yang banyak digunakan antara lain adalah kobalt kromium dan stainless steel. Stainless steel 316L merupakan austenistic stainless steel yang memiliki komposisi karbon rendah sehingga dapat meningkatkan ketahanan terhadap korosi sama halnya dengan kandungan molybdenum pada material tersebut. Kobalt kromium (CoCr) adalah cobalt-based alloy dengan campuran chromium. Kepadatan (density) dari logam campur kobalt kromium adalah sekitar 8-9 gram/cm 3 menyebabkan logam campur ini relatif sangat ringan. Remanium GM-800 merupakan salah satu jenis alloy kobalt kromium dengan kelebihan memiliki resistensi terhadap fraktur yang tinggi serta modulus elastisitas yang tinggi. Penelitian ini bertujuan untuk mengetahui konsentrasi tepat yang digunakan pada stainless steel 316L dan kobalt kromium GM-800 sebagai bahan uji GPMT. Subjek penelitian adalah kobalt kromium Remanium GM-800 dan stainless steel 316L konsentrasi 5%, 10%, 20%, 40%, dan 80%. Patch berisi pasta stainless steel atau kobalt kromium ditempelkan selama 24 jam masing-masing pada 3 hewan coba, selanjutnya dilakukan observasi eritema dan edema dengan menggunakan skala Magnusson dan Kligman. Pada penelitian, konsentrasi 5% merupakan konsentrasi yang direkomendasikan untuk stainless steel 316L dan kobalt kromium GM-800 sebagai konsentrasi tahap challenge uji GPMT, sedangkan konsentrasi 40% merupakan konsentrasi yang direkomendasikan untuk logam stainless steel 316L dan kobalt kromium GM-800 tahap induksi.Kata kunci: GPMT, hipersensitivitas tipe IV, kobalt kromium GM-800, stainless steel 316L Keywords: GPMT, type IV of hypersensitivity, cobalt chromium GM-800, stainless steel 316L ABSTRACT PENDAHULUANLogam merupakan material yang umum digunakan untuk  ksasi tulang. Mulai dari hal sederhana seperti kawat dan sekrup untuk pelat yang bebas dari patah hingga total joint prostheses (tulang sendi buatan) untuk pangkal paha, lutut, bahu maupun pergelangan tangan. Dalam dunia kedokteran logam banyak digunakan pada pembedahan maxillofacial, cardiovascular, dan sebagai material dental. Logam yang banyak digunakan antara lain adalah kobalt kromium dan stainless steel.

Stainless steel and cobalt chromium is a metal that is used in dentistry. Stainless steel (SS) 316L has good corrosion resistance, but there are still many cases of hypersensitivity due to the use of such materials. Remanium GM800 is a cobalt-based alloy which is relatively mild with the advantages of having a high fracture resistance, high modulus of elasticity and resistance to corrosion. The research aims to know type IV hypersensitivity reactions for cobalt chromium GM800 applications compared with 316L Stainless steel. The research was conducted through the test GPMT (Guinea Pig Maximization Test). The pre-research phase does CoCr patch/SS/control application to 3 guinea pigs of each group with concentrations of 5%, 10%, 20%, 40%, and 80%. Primary research begins with intradermal induction on the backs of guinea pigs for 7 days with a suspension of A (50% FCA emulsion dan 50% Propylene glycol), B (SS/CoCr/blank dan Propylene glycol) and C (50% SS/CoCr/blank suspension and 50% FCA) on the left and right backs of guinea pigs. On the 8th day induction results topical concentration of 40% for 24 hours, then opened to see the reaction and closed again for 48 hours. After that, the research was continued with challenge phase by attaching patch 5% concentration for 14 days. On the 28th  day was observed erythema and edema on the skin of guinea  pigs followed by sacrifice in order to obtain specimen to do immunohistochemical staining by ED antibodies. The result showed 316L SS cause 40% of the samples sensitized that were grouped in moderate classification, while CoCr GM800 cause 20% of the samples sensitized so classified in the mild classification in triggering type IV hypersensitivity reaction. Histopathology examination showed that 42% of the visual field SS 316L specimen expressed macrophages, while only 28% expressed macrophages in CoCr GM800 specimen. The conclusion of this study CoCr GM800 trigger type IV hypersensitivity reaction is lower than SS 316L.