Learning Objectives: 1. Understand need for reconstruction of the posterior canal wall in canal wall down mastoidectomy 2. Describe the different types of bone cements that are available for mastoid/PCW reconstruction 3. Know the indications and contraindications for use of cement(s) in chronic ear cavities.

Long-term management of the canal wall down mastoidectomy cavity remains a concerning issue. Quality of life (QOL) measures are reduced in patients with large mastoidectomy bowls that necessitate life-long otologic care. Interestingly, QOL between patients with intact canal wall mastoidectomies and reconstructed canal wall down mastoidectomies is not different. This has spurred attention to various posterior canal wall reconstruction techniques. Since the early 1980s various cements have been tried for reduction of cavity/bowl size and reconstitution of the posterior canal wall. These have fallen into and out of favor as long-term results have become available. The bed should be as pristine and clean as possible before the cement foreign body is placed there. Cement can be used alone or in conjunction with a free island of bone – either from the posterior canal wall or from the cortex of the skull. Certain cements, such as glass ionomers, cannot be used if there is potential contact with cerebrospinal fluid because of possible aluminum encephalopathy. Care must be taken for early identification and treatment of local infection (6% to 35%) or delayed extrusion of the cement. In clean, selected cases, bone cement can be used as a tool for mastoid reconstruction when the canal wall must be removed due to extent of disease. Types of available cements, techniques for use, clinical ‘pearls’ and images of good and bad reconstructive outcomes will be presented.