Background: Aspartate aminotransferase (AST) is an enzyme normally confined
to the cytoplasm of cells, but released to the extracellular environment u
pon cell death. Its levels are associated with the severity of experimental
gingivitis and the loss of periodontal attachment. The aim of the present
study was to investigate the presence and activity levels of AST in peri-im
plant crevicular fluid (PCF) from healthy and diseased endosseous implants
in order to assess if AST in PCF can be further studied as a possible objec
tive diagnostic aid in oral implantology.
Methods: Eighty-one fixtures from 81 systemically healthy subjects were div
ided into 3 groups, 27 healthy implants (HI), 27 implants with mucositis (M
I) and 27 implants affected by peri-implantitis (PI) according to well-defi
ned clinical and radiographic criteria. PCF was collected by the insertion
of a # 40 standardized endodontic paper point to the base of the crevice or
pocket for 30 seconds. AST activity was determined spectrophotometrically
at 25 degreesC. The results were expressed as AST Units/ml in PCF.
Results: An AST activity was detected in each sample from HI, MI and PI. Th
e mean AST activity in HI was 0.26 +/- 0.16 U/ml; in MI, 0.38 +/- 0.27 U/ml
; in PI, 0.62 +/- 0.29 U/ml. ANOVA showed that the difference among HI, MI,
and PI was statistically significant at P <0.01 level. Post-hoc tests demo
nstrated that a significant difference in AST activity existed between HI/P
I (t = 5.14; P <0.01) and MI/PI (t = 3.09; P<0.01). No statistically signif
icant difference was found between HI/MI (t = 1.07; P>0.1) AST activity was
significantly (P <0.01) associated with probing depth (r = 0.55), the amou
nt of bone loss (r = 0.60) and bleeding on probing (r = 0.67). When the thr
eshold for a positive AST test was set <greater than or equal to>0.4 U/ml,
a sensitivity = 0.81 and a specificity = 0.74 were found in the detection o
f peri-implantitis; the positive predictive value was 61% and the negative
predictive value was 88%.
Conclusions: Within the limits of this study, our results may suggest that
PCF analysis could be further investigated in longitudinal studies as a sui
table diagnostic strategy in the evaluation of dental implants.