Liberação dos fatores de crescimento TGF β1 e VEGF após condicionamento dentinário com agentes quelantes: análise ex vivo

Abstract

Growth factors sequestrated in dentin play an important role in the repair process of the dentino pulp complex. The aim of this study was to investigate, ex vivo, the release of growth factors TGFβ1 e VEGF, sequestrated in dentin, after conditioning with the chelating agents: EDTA, Chitosan and Etidronic Acid (HEBP). The smear layer removal and the dentin tubules erosion were also analysed. by SEM. A total of seventy two teeth met the following criteria: permanent teeth with single rooted teeth, without caries, fractures, resorption and/or previous endodontic treatment, were selected for the preparation of specimens. The crowns and the apical portion of teeth were removed and root segments were prepared to cylinder shape with 8 mm. The root segment was instrumented up to Gates Glidden size 4 to standardize the internal diameter at 1mm.Thirty six specimens were initially irrigated with 20 mL/5 min of NaOCL and then randomly assigned into four groups (n=9 for each group) with different final irrigation protocols: 17% EDTA (20mL/5 min); 0.2% Chitosan (20 mL/5 min); 9% HEBP (20 mL/ 5min); Saline (20 mL/5 min).After the final irrigation the specimens were kept in an 1,5mL Eppendorf microtubes containing α-MEM medium and 100 U/mL penicilin e 100 U/mL de estreptocimicin at 37°C for twenty four hours. After that time the medium from thirty six Eppendorf tubes were collected and the growth factors release was quantified using an immunoenzymatic test ELISA. The data were not submitted to any statistical test because the release of growth factors TGF β1 e VEGF was not detected in any tested group. Longitudinal grooves were made on the mesiodistal surfaces of another thirty six specimens using a low-speed diamond disk. Photomicrographs of the cervical, middle and apical thirds in order to compare the effectiveness of different chelating agents the smear layer removal and the degree of the dentinal tubules erosion, using electron microscopy (SEM). Data were submitted to the non- parametric tests Kruskal-Wallis and Dunn with a significance level of α = 0,05. The final irrigation protocols with the chelating agents EDTA 17%, Chitosan 0,2% and HEBP 9% was efficient in removing the smear layer and promote some erosion in the dentine tubules, with no significant difference between the tested groups. Based in the methodology employed and according to the results of this study ita can be concluded that: a) it was not possible to quantify the release of growth factors TGF β1 and VEGF with the ELISA kit used; b) As all the chelating agents tested were efficient in smearlayer removal and promote some degree of dentin tubules erosion, in all regions analysed, Chitosan 0,2% can be a natural substitute for EDTA 17%.