Histological evaluation of the soft tissue response to plasma-activated healing abutments: A prospective controlled clinical trial.

Abstract

Purpose: This prospective clinical trial aimed to histologically evaluate peri-implant soft tissue response to healing abutments treated with a vacuum plasma reactor.

Methods: Thirty bone-level implants were placed with machined healing abutments designed to be retrieved using a calibrated mucotome after soft-tissue healing. Test abutments were plasma-activated immediately before placement, whereas control abutments were left untreated. After 3 months, plaque index and bleeding on probing were recorded prior to collecting peri-implant soft-tissue biopsies. The specimens were processed and evaluated clinically and histologically.

Results: Thirty patients with 30 implants completed the study. Histological evaluation showed lower inflammation scores in the basal zone around plasma-activated abutments (P = 0.04). Mean inflammation scores in the test group were 2.78 ± 0.7, 2.52 ± 0.5, and 1.72 ± 0.5 in the upper, intermediate, and basal zones, respectively, compared with 3.28 ± 0.8, 2.93 ± 0.6 and 2.36 ± 0.5 in controls. Connective-tissue maturation and epithelial regeneration were comparable between groups (approximately 3.1 and 3.0, respectively). Vascularization was slightly higher in the test group (1.20 ± 0.19 vs. 1.09 ± 0.05). The cornified layer contacting the abutment was significantly thicker in the test group (2.89 ± 0.8 vs. 1.91 ± 0.7, P = 0.008). No significant differences were observed for plaque index, whereas bleeding on probing was lower in the test group.

Conclusions: Plasma-activated healing abutments were associated with localized histological differences at the epithelial-abutment interface, particularly in basal inflammation and cornified layer thickness, while most parameters remained comparable between groups.