CASE REPORT Histological evaluation of the peri-implant tissues of three human-retrieved Straumann implants Claudia Dellavia 1 , Daniela Carmagnola 1 , Stefano Storelli 2 , Alessandro Rossi 2 , Elena Canciani 1 & Eugenio Romeo 2 1 Department of Human Morphology and Biomedical Sciences ‘‘Citta ` Studi’’, Universita ` degli Studi di Milano, Milan, Italy 2 Dental Clinic, Department of Medicine, Surgery and Dentistry, Universita ` degli Studi di Milano, Milan, Italy Introduction The criteria for the clinical success of rehabilitation by dental implants include the absence of persistent signs and symptoms, such as pain, infection, neuropathies and paresthesias, implant stability, no peri-implant radiolu- cency, <0.2 mm annual bone loss during the first year, and patient/dentist satisfaction with the restoration. 1–4 The most frequently-used histological parameters to define dental implant osseointegration include bone- to-implant contact (BIC) and quantitative and qualitative assessments of the tissue surrounding the fixture. Human histological evidence of clinically successful implants is extremely rare in the literature. The retrieval of histologi- cal samples from long-term, functionally-loaded human implants has been possible for psychiatric or oral onco- logic reasons, or if the patient is dead. 5–9 The aim of this paper was to present the histological features of the bone tissue surrounding three well-functioning SLA and SLActive (Straumann AG, Waldenburg, Switzerland) implants placed in two patients after 12 and 60 months of functional loading. Case 1 In 2004, two implants were placed in the left mandibular region of a 53-year-old partially-edentulous woman at the Dental Clinic of the Department of Medicine, Surgery and Dentistry of University of Milan (Milan, Italy). Under local anesthesia, two SLA implants were inserted into the molar and premolar areas of the lower jaw. The mesial implant was a ‘‘regular neck’’ 4.1 · 10-mm implant, while the distal implant was a ‘‘wide neck’’, 4.8 · 10-mm implant. Three months later, an implant- supported bridge of three elements was connected to the fixtures. Despite follow-up clinical and radiological parameters indicating that the rehabilitation was success- ful, the patient reported to have developed a persistent headache due to ‘‘magnetic fields’’ originating from the implants. The patient was referred to a neurologist and a psychiatrist without success. Eventually, under local anes- thesia, the smooth collar of the distal implant was cut in order to reduce the wide-neck diameter, and the fixture was removed with a 5.5-mm trephine bur. After 8 weeks, the mesial implant was also removed. The second implant Keywords bone-to-implant contact, dental implant, histology, human, osseointegration. Correspondence Dr. Daniela Carmagnola, Department of Human Morphology and Biomedical Sciences, University of Milan, Via Mangiagalli 31, 20133 Milan, Italy. Tel: +39-02-5031-5405 Fax: +39-02-5031-5387 Email: daniela.carmagnola@unimi.it Received 16 September 2010; accepted 24 December 2010. doi: 10.1111/j.2041-1626.2011.00052.x Abstract The most frequently-used histological parameters to define dental implant osseointegration include bone-to-implant contact and quantitative and qualita- tive assessments of the surrounding tissue (rate of mineralized/non-mineralized tissue and proportion of lamellar and woven bone compared to soft tissue or bone marrow). The aim of this paper was to present the histological features of the bone tissue surrounding three well-functioning Straumann SLA and SLActive implants placed in two patients after 12 and 60 months of loading. The percentage of osseointegration ranged from 66.4% and 71.9% for SLA surfaces, to 88.3% for the SLActive implant. Such results confirm that osseo- integration occurs with high rates of bone-to-implant contact in humans, and that implants can be similarly clinically successful, although they show different bone-to-implant contact values. Journal of Investigative and Clinical Dentistry (2011), 2, 216–220 216 ª 2011 Blackwell Publishing Asia Pty Ltd