Effect of different localizations of microgap on clinical parameters and inflammatory cytokines in peri-implant crevicular fluid: a prospective comparative study

The purpose of this study was to evaluate the effect of microgap on clinical and biochemical parameters around dental implants for 1 year. All patients received four implants: group A-Standard Straumann(A (R)) implants, group B-1 mm subcrestal placement of the polished surface of group A implants, group C-esthetic plus StraumannA (R) implants, group D-subcrestal placement of the polished surface of group C implants. Clinical measurements and peri-implant crevicular fluid (PICF) were collected immediately before loading and at 3rd, 6th, and 12th months after loading, and interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) have been assessed in the crevicular fluid. No significant differences were found in plaque index, gingival index, and probing between the groups throughout the study. However, the PICF volumes of group D were significantly higher than that in the other groups, and group A were significantly lower than the other groups (P < 0.05). With respect to bleeding on probing values, the percentage of BOP (+) sides in group A implants were fewer than group C and D implants (P < 0.05). With regard to IL-1 beta, the levels of IL-1 beta in group A were lower than that in the other groups during the study (P < 0.05). In point of TNF-alpha total amounts, the levels of TNF-alpha in group A implants were lower than those in group B and D implants (P < 0.05). Moving microgap coronally from alveolar crest could be recommended for the health of periodontal tissues. Most coronal location of microgap can be suggested in order to maintain the peri-implant health status, particularly in implant sites without esthetic priority.