The purpose of this communication is to describe the indications, surgical technique and anatomical and function results of the mastoid and epitympanic obliteration using bone substitutes. This technique employed in our department since 2006, encompasses the use of synthetic biomaterials for the obliteration of mastoid and epitympanic spaces. Granules of biphasic ceramic have been used up to 2012 (n = 130) and, since 2013 (n = 74) we are using bioactive glass S53P4. Differences in composition and mechanism of action will be detailed, with particular attention to the antibacterial activity of the bioactive glass S53P4.