Soft tissue response to titanium healing abutments treated by Er: YAG laser or plasma spray: A randomized controlled feasibility clinical study with SEM and histological analysis.

Objective: Soft tissue seal around implants ensures stable osseointegration and a long-term survival of dental implants. Different surface modification and decontamination for implant abutments were endorsed in order to improve peri-implant soft tissue healing, such as laser, plasma spray, acid etching, and steaming. The aim of this study was to evaluate the response of peri-implant soft tissue to titanium abutments treated with Erbium-doped: Yttrium-Aluminum-Garnet (Er:YAG) laser versus plasma spray.

Methods: Twenty-four patients who required implant placement in the maxillary arch participated in this study. Patients were divided into three groups, abutments treated with Er:YAG laser versus cold plasma spray and untreated abutments. Fourteen days following the implant abutment insertion, soft tissue peri-implant biopsies were taken for histological, histochemical, and immunohistochemical evaluation. Scanning electron microscopy was done for the abutments; plaque index (PI) and gingival index (GI) were assessed 14 days and 3 months following final restoration.

Results: Regarding the histological results, the least mean inflammatory cell count was in the plasma group (174.09 ± 40.67), followed by the laser group (654.27 ± 85.95) and the control group (852.00 ± 117.98), with statistically significant differences between them. The mean area fraction of collagen fibers showed the highest value in the plasma group (9.73 ± 1.91), followed by the laser group (3.25 ± 0.49), while the lowest value was found in the control group (1.17 ± 0.51). The immunohistochemical expression of E-cadherin was significantly higher and uniformly distributed in the plasma group (42.4 ± 11.2%) followed by the laser group (15.4 ± 4.07%) and the control group (6.8 ± 1.7%). SEM analysis of healing abutments showed fibroblast-like cells, which were more developed with dense fibers in the plasma group; laser group fibers showed fewer and more delicate fibers than the plasma group, while no fibers were detected in the control group.

Conclusion: Within the limitations of this feasibility study, the present data concluded that plasma spray and Erbium: YAG laser can be used for abutment surface treatment to achieve better peri-implant soft tissue healing. Clinically and histologically, plasma spray showed a better effect on the peri-implant soft tissues by reducing the inflammatory reaction, promoting collagen fiber formation, higher fibroblast-like cell attachment, and upregulating E-cadherin expression than Erbium: YAG laser and control groups.