Introduction: The creation of the “open cavity” to clear cholesteatoma results in significant morbidity in over a third of patients. Various biological and non-biological materials have been used to reduce or obliterated these mastoid cavities. Materials and Methods: This study reports the technique and results of using hydroxyapatite granules with a pericranial flap to obliterate troublesome cavities. Results: 50 mastoid obliterations were performed in 48 patients. 94% no longer required water precautions 2 months post-operatively and may use conventional hearing aids. Discussion: This technique improves patients’ quality of life and can enable discharge of patients previously reliant on ENT services.