Evaluation of peri-implant soft tissue status through inflammatory biomarkers on laser treated healing abutments. A human study

DM7IV ORAL COMMUNICATION CLINICAL RESEARCH – PERI-IMPLANT BIOLOGY

Background: Among the factors that influence the survival of implant rehabilitations, implant-abutment interface and the peri-implant soft tissues play a key role. Different study was performed but there is still deficiency of information on interaction between peri-implant soft tissue and different surface treatment or topography. It was reported that the gingiva adherent to the laser treated surface maintain a regular morphology, while a granulocytes infiltration was observed adjacent maCHINAd surfaces.

Aim/Hypothesis: The aim was to evaluate the inflammatory microenvironment around the healing abutment in order to evaluate whether the surface treatment on healing abutment could have a protective role against inflammation positively influencing the peri-implant soft tissue healing and their stability

Materials and Methods: A total of 30 experimental custom-made healing abutments have been collected after the healing period (30 ± 7 days). Each healing abutment was treated with two alternated different surface treatments (maCHINAd and experimental laser treated surface) in order to eliminate the bias of the different surface allocation. The “G. d'Annunzio” Chieti-Pescara University Ethic Committee has approved this clinical trial N° 22 of 18.10.2018: 15 samples were treated for quantitative real time PCR (qPCR), the other 15 for immunohistochemical analysis, in order to obtain information on the inflammatory state of the soft tissues. Specifically, the pro-inflammatory cytokines TNF- α, the neutrophil chemoattractant MMP-9, MMP-9 inhibitor TIMP-1 gene expressions, cytokine IL-10, IL-6, ICAM-1 and Cytokeratins 18 and 19 was observed. Analysis of variance, Kruskal-Wallis, Bonferroni-Dunn posthoc and Mann-Whitney tests was used as appropriate to detect different between the Groups.

Results: Soft tissue around the laser-treated surface expressed lower levels of the pro-inflammatory cytokines TNF- α and MMP-9 together with higher levels of the MMP-9 inhibitor TIMP-1 gene expressions. In addition, the mRNA of the anti-inflammatory cytokine IL-10 was statistically more expressed (P < 0.001) in the gingiva samples facing the laser-treated surface. Meanwhile, no statistical differences were found in IL-6 expression. Immunofluorescent analysis confirmed that MMP-9 was nearly undetectable around the laser treated surface, while was evident in the other group. Additionally, some MMP-9 positive areas, marked alterations and discontinuity of the basal lamina were also detected. Analysis evidenced slightly expression levels of ICAM-1 in laser treated, while it was dramatically overexpressed in the maCHINAd one. A strong and statistically significant positive reaction (P < 0.001) of CK-18 and CK-19 was detected in the epithelium faced to the maCHINAd surface.

Conclusions and Clinical Implications: The degree of tissue damage is due to an unbalanced level of pro and anti-inflammatory mediators. The new laser treated surface showed a statistically significant weaker expression of several markers, indicating a protective effect of this treatment. These results will open new research fronts on laser treatment in perimplant portion. It is believable that it has good chances to influence positively the maintenance of peri-implant soft tissue and the challenging coronal biological seal formation

Keywords: peri-implant soft tissues, laser treated surface, healing abutment, human study.