Inflammatory infiltrate, microvessel density, vascular endothelial growth factor, nitric oxide synthase, and proliferative activity in soft tissues below intraorally welded titanium bars

Background: The aim of the present study is a comparative evaluation of inflammatory infiltrate, microvessel density, vas- cular endothelial growth factor, nitric oxide synthase, and prolif- erative activity in soft tissues below intraorally welded titanium bars. Methods: Twenty-two patients participated in this study. All patients carried immediately loaded one-stage titanium implants splinted with intraorally welded titanium bars. Each patient un- derwent two gingival biopsies, a control biopsy harvested from an area of mucosa 5 mm away from the titanium bar and a test biopsy from the mucosa below the titanium bar, which were his- tologically and immunohistochemically processed. Results: No fractures or radiographically detectable alter- ations of the welded frameworks were present. In all the cases examined, the average of the modified plaque index was 1, no suppuration or bleeding on probing was present, and probing depth was £3 mm. However, the immunohistochemical analysis revealed some differences. The inflammatory infiltrate was mostly present in test sites and its extension was much larger than in control sites. Statistically significant differences were found in microvessel density and Ki-67 expression among con- trol and test groups (P <0.0001). The high intensity of vascular endothelial growth factor, nitric oxide synthase 1, and nitric ox- ide synthase 3 expression were mainly detected in the test group, whereas the low intensities were mostly expressed in controls, with statistically significant differences (P <0.0001). Conclusions: In the present study, the immunohistochemical analysis shows that the tissues below the titanium bars under- went a higher rate of inflammatory and reparative processes. However, further long-term studies, where clinical and immuno- histochemical data are collected in parallel, should be conducted for a better understanding of the expression pattern of inflamma- tion markers. J Periodontol 2010;81:748-757. KEY WORDS Dental welding; immunohistochemistry; inflammation; neovascularization; soft tissue; titanium.