Influence of nicotine on osseointegration of implants installed in the tibia of rats: biomechanical, histological, histometric and immunohistochemical evaluation

Author(s)

Paula Lazilha Faleiros

• Document type: Doctoral Thesis
• Press: Araçatuba. 2016-08-03.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2016-07-05
• Advisor: Alvaro Francisco Bosco; Juliano Milanezi de Almeida; Valdir Gouveia Garcia

Abstract

Objective: To evaluate, from biomechanical, histomorphometric, histochemical stand point and through of immunohistochemical markers, the influence of low level laser therapy (LLLT) on the osseointegration of implants placed in the tibias of nicotine systemically modified (or not) rats. Materials and methods: A total of 120 rats (Wistar) was assigned into two major experimental groups (n = 60) underwent two-daily-applications of saline (Veh) or nicotine (Nic). After thirty days, titanium implants (2.2 mm x 4 mm) were placed in the proximal metaphysis of both tibiae from all animals. Experimental groups of different surgical alveolus local treatments prior to implant placement (n = 30) were created at the moment of the surgery: Veh - no local treatment; Veh/LLLT - irradiation of surgical alveoli with low level laser; Nic - no local treatment; Nic/LLLT - irradiation of surgical alveoli with low level laser. The laser used was Thera Lase® (InGaAIP 660 nm, in continuous mode, in contact with the area, 35 mW, 0.14 J, 4.9 J/cm2 , for 4 seconds). Ten animals from each group were euthanized at 15, 30 and 60 days postoperative. The right tibiae were submitted to reverse-torque analysis and, then processing in order to prepare decalcified histological sections, stained either by hematoxylin and eosin or picrosirius red or subjected to immunohistochemical reactions with the primary polyclonal antibodies: HIF-1 α, VEGF, BMP-2, RUNX-2, OCN, ALP, RANKL, OPG and TRAP. From left tibias were prepared undecalcified histological sections to evaluate the percentages of bone-to-implant contact (BIC) and bone area (BA) within the limits of the implant threads. The histochemical analysis was performed by a polarized light microscopy and the histological, histometric and immunohistochemical analysis were performed by a bright field optical microscopy. The HIF- 1α, VEGF, BMP-2, OCN, ALP, RANKL and OPG immunostaining were submitted to qualitative analysis and the RUNX-2 and TRAP immunostaining were submitted to quantitative analysis. Quantitative data were analyzed statistically (p≤0.05). Results: The nicotine delayed the production of bone matrix components, decreased the imunolabeling pattern of HIF-1α, VEGF, BMP-2, OCN, ALP and OPG, increased the imunolabeling pattern of RANKL, increased the amount of RUNX-2 and TRAP-immunoreactive cells, reduced the BA, but did not influence the BIC and the force required to break the osseointegration. The laser increased the imunolabeling pattern of HIF-1α, VEGF, BMP-2, OCN and ALP, increased the amount of RUNX-2 and TRAP-immunoreactive cells, increased the BA, but also was not be able to influence the BIC and the force required to break the osseointegration. In addition, the laser positively influenced the BA and the implant removal torque, increased the angiogenesis and osteoblast differentiation, promoted bone formation, biomineralization and peri-implant bone maturation in the nicotine systemically modified rats. Conclusions: LLLT is able to promote the peri-implant bone repair process in normal conditions and is able to compensate the negative effects of nicotine on osseointegration. (AU)

• FAPESP's process: 13/11863-0 - Influence of low level laser therapy on osseointegration of implants installed in the tibia of systemically nicotine-modified rats or not: biomechanical, histological, histomorfometric, histoquimical and immunohistochemical evaluation
• Grantee: Paula Lazilha Faleiros
• Support Opportunities: Scholarships in Brazil - Doctorate