Purpose: To evaluate the response of human peri-implant soft tissue (PIST) on different healing

abutment materials 24 hours after positioning, by assessing the expression of genes related to the

early connective tissue wound healing response. Materials and Methods: Experimental abutments of

4 different materials (A): grade 4 titanium, (B) grade 5 titanium, (C) zirconia and (D) PEEK, were

mounted on installed implants in 5 patients, four different abutments each. Before implant

placement, a gingival biopsy (control-CT) was obtained using a 2 mm diameter punch (T0). After

24 hours (T24), PIST biopsies were collected using a specifically designed custom-made cutting

device. Real-time PCR was performed to analyze the expression of the following genes: COL-I,

COL-III, MMP-1, TIMP-1,TGF-b1, FN, ITGA4, ITGA5, ITGB1, RAC-1, COL-IV, aSMA, IL-6

and CXCL-1. Results: Gene expression analysis showed some differences between CT and

abutment of different materials, although no significant differences were detected comparing the

experimental groups. COL-I was significantly down-regulated in groups A and C compared to CT.

MMP-1 and TIMP-1 increased in all the experimental groups, although at a lower extent in group

A. FN, RAC-1, COL-IV and aSMA were down-regulated, especially in group A, in which CXCL-1

and IL-6 showed the lowest expression. Conclusions: The results of grade 4 titanium and zirconia

abutments seem to be promising, since a lower expression of genes related with inflammation,

myofibroblasts activation and ECM remodeling was observed when compared with grade 5

titanium and PEEK, without triggering a pro-fibrotic response in the early phases of PIST repair.