Longitudinal evaluation of aspartate aminotransferase in the crevicular fluid of implants with bone loss and signs of progressive disease.

Aspartate aminotransferase (AST) has been shown to be a promising host marker for periodontal disease progression. The aim of the present study was to analyze AST in the crevicular fluid (CF) of implants exhibiting peri-implantitis and to evaluate the association between AST levels and progressive attachment loss. Twenty patients who had received a total of 42 endosseous cylindric titanium implants were examined. Radiographic assessment of preexisting bone loss and clinical measurements, including electronic attachment of probing, presence or absence of plaque, bleeding on probing, and AST analysis in CF, were performed on 2 occasions 6 months apart. During this study period 13 of 168 sites in 7 patients experienced further loss of attachment greater than or equal to 1.0 mm (median 1.7 mm; interquartile range 0.4 mm). Evaluation of a positive AST test (> or = 300 microIU) in site-specific diagnosis revealed low positive (8%) and high negative predictive values (92%), with a sensitivity of 15% and a specificity of 83%. These results indicate that, in contrast to periodontal disease, the assessment of AST in peri-implant crevicular fluid may be of limited value as a diagnostic and prognostic marker for peri-implant disease.