Histological analysis of implants removed from the oral cavity, a case series

OBJECTIVES Dental implants are widely used to rehabilitate maxilla of partial or to-tal edentulous patients, however, despite the increase in the implant survival rate, both early and late failures still occur. The early failure of an implant de-rives from not being able to obtain a sufficient and adequate osseointe-gration; in this case, the bone healing after the insertion of the implant is compromised and may depend on local and systemic factors such as diseases, intake of certain drugs or bad habits such as smoking, which can interfere with wound healing. Late implant failures, on the other hand, are more related to the oral microbial environment, parafunctions, or prosthetic errors. The aim of this study is to de-scribe and compare different causes of early and late implant failure through histological and ra-diographic analysis of several clinical cases. MATERIALS AND METHODS Five clinical cases are presented in this study, relating to 5 implant fail-ures, which occurred after different loading periods and due to different causes. Each case has been docu-mented both radiologically and, after the removal of the bone samples containing the implants, also histologically. These biological samples were removed from the oral cavity of the patients, in order to be able to proceed with the dental rehabilitation procedures, which had previously been agreed with the patients. In order to proceed with the histological analysis, the bone samples were subjected to a dehy-dration procedure with increasing concentrations of alcohol, inclusion in a glycol-methacrylate resin, sec-tioning with the aid of a high preci-sion diamond disc until reaching the thickness of 150 microns, sub-sequent abrasion up to about 30 microns, and coloring with acid fuchsin and toluidine blue. The analysis of the samples was carried out under a transmitted light optical microscope. RESULTS AND CONCLUSIONS Of the 5 implants presented, one represents an early failure, because removed <6 months from insertion; the other late failures, since removed between 7 and 18 years from insertion. The histological analysis has made it possible to obtain more information, relating to the actual causes of implant failure, as op-posed to radiographic images, which are useful above all for di-agnosis, but give little information regarding the real causes. In particular, while the radiological images showed only the presence of a generic radiolucency that started from the implant collar and extended towards the apical portion, in the histologic section it is possible to observe the type of cells that composed these tissues. In particular, in the histological analysis it is possible to check for the presence of inflammatory in-filtrated tissue which allows us to differentiate physiological bone resorption, part of the normal re-modeling processes, from the pathological one, due to peri-im-plantitis. CLINICAL SIGNIFICANCE In order to make a correct diagnosis and therefore decide for the best treatment, it is essential to analyze the greatest number of in-formation, both clinical and radio-logical. The use of histological analysis in some cases, however, allows us to obtain unique infor-mation, fundamental not only in research but also in the clinic.