Full text
| |
| Author(s): |
Melissa Thiemi Kato
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Bauru. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB) |
| Defense date: | 2011-07-01 |
| Examining board members: |
Marilia Afonso Rabelo Buzalaf;
Marcela Rocha de Oliveira Carrilho;
Fausto Medeiros Mendes;
Rodrigo Cardoso de Oliveira;
Jose Carlos Pereira
|
| Advisor: | Marilia Afonso Rabelo Buzalaf |
| Abstract | |
The dentin degradation by matrix metalloproteinases (MMPs) can increase the progression of erosive lesions. Objectives: Five studies were conducted to evaluate: 1) The activity of MMPs in bovine and human dentin; 2) The effect of green tea rinse against dentin erosion/abrasion; 3 and 4) Gels containing MMP inhibitors (epigallocatechin-3-galatte-EGCG, chlorexidine-CHX and ferrous sulphate-FeSO4) to prevent dentin erosion alone or associated with abrasion, respectively, and 5) On collagen degradation and wear. Material and Methods: 1) Protein extraction from crown and root of bovine and human dentin was performed (0.87 M citric acid, pH 2.3) and tested by zymography and gelatinolytic activities; 2) Volunteers (n=10) rinsed with green tea or water (1 min, 10 mL) between the erosive (Coke, pH 2.6, 4x5min/day, extraorally) and abrasive challenges. The abrasion (electric toothbrush + fluoride-free toothpaste) was performed immediately or 30 min after erosion for 30 s. Dentin wear was analyzed by profilometry (µm); 3 and 4) Volunteers (n=10-13) wore palatal devices containing 12 bovine dentin blocks randomly allocated to 6 groups, according to the type of gels applied or not (not treated-NT). The gels had identical composition, except for the presence of EGCG (400 µM), CHX (0.012%), FeSO4 (1 mM), fluoride (NaF-1.23%) or not (Placebo-P). Gels were applied or not on specimens once in a thin layer and removed after 1 min. Erosion (Coke, pH 2.6, 4x5 min/day, extraorally) was performed for 5 or 10 days, respectively. Each day, after first and last erosive challenges, blocks were (ERO) or not brushed (ERO+ABR) for 15 s (electric toothbrush + fluoride-free toothpaste slurry). Dentin wear was evaluated by profilometry (µm) after days 5 and 10. 5) Demineralization of dentin (n=45/group) was performed with 0.87 M citric acid, pH 2.3, for 36 h. In sequence, dentin was or not (NT) treated with the same gels described above. Specimens were stored in artificial saliva (5 days, 37ºC), containing EDTA-free protease inhibitors and collagenase (Clostridium histolyticum, 238 U/mL). Collagen degradation was analyzed by hydroxyproline content (µg/mL) and dentin wear was evaluated by profilometry (µm, n=12/group). Data were analyzed by ANOVA (p<0.05). Results: Bovine dentin showed to be a reliable substrate for studies involving the activity of MMPs. Green tea significantly reduced the dentin wear for all conditions. The mean wear and collagen degradation was significantly reduced for the experimental gels when compared to NaF and P gels or NT in all protocols tested. For ERO, wear did not significantly increase with time, while for ERO+ABR, significant increase along time was observed for NaF, P and NT. Association between ERO and ABR was only able to significantly increase the wear at 10 days for NaF and NT. Conclusion: The use of green tea rinse and a gel as a vehicle to deliver MMP inhibitors to dentin was shown to consistently reduce collagen degradation and provide long-lasting prevention against dentin erosion and erosion plus abrasion. (AU) | |