Apoptosis in peri-implant tissue

The authors examined 54 biopsies taken from the tissue surrounding loosened hip joint prostheses. In situ apoptotic cell identification was performed by the detection of single- and double-stranded DNA breaks that occurred in the early stages of apoptosis. Both types of breaks can be revealed by lab eling the free 3'-OH termini with modified nucleotides (fluoresceine-dUTP) in an enzymatic reaction catalyzed by terminal deoxynucleotidyl transferase (TdT). Results were correlated with the presence of wear debris in the tis sue and with the use of bone cement for prosthesis fixation. Apoptotic cell s were present in a higher percentage in tissue sections where metal partic les were present (24% apoptotic cells) if compared to areas where no wear ( 6%), or plastic wear (2.8%) or ceramic wear (1.5%) was observed. Apoptosis is neither related to bone cement, nor to the time it takes for the implant to fail. Cell death by apoptosis may be important in implants which releas e metal ions by corrosion or wear and may have been underestimated up to no w, as it is a 'clean' way of cell death, leading to limited damage in the s urrounding tissues. (C) 2000 Elsevier Science Ltd. All rights reserved.