A PubMed search was carried out using the search terms cholesteatoma, middle ear/ or mastoiditis/ or otitis media, suppurative/ or tympanic membrane perforation; randomized controlled trial; controlled clinical trial; randomized controlled trials/ random allocation/ double-blind method/ single-blind method. Comparative study/ exp evaluation studies/ follow-up studies/ prospective studies. Placebos/random. Limited to animal; limited to human; animal and human. An additional search for inactive squamous COM used the search terms: tympanic membrane and/or retraction.