A 40 year old male patient complains of decayed tooth. Patient gives history of cavity preparation and restoration with low copper amalgam done with 26. Intra-oral examination reveals proximal caries with 26. During electrochemical corrosion of this restoration, which of the following helps in sealing the space against microleakage?​

During electrochemical corrosion of low-copper amalgams, the Sn-Hg phase is oxidized into Sn-O and/or​ Sn-O-Cl. The oxychloride species is soluble. The oxide precipitates as crystals and tends to fill up the spaces​ occupied by the original Sn-Hg phase. Along the margins of the amalgam, Sn-O helps seal the space against​ microleakage.​ Reference: Sturdevant’s Art and Science of Operative Dentistry, Mosby, 4th Edition, Page No: 155​