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| Author(s): |
Ana Cecilia Corrêa Aranha
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Odontologia (FO/SDO) |
| Defense date: | 2005-08-03 |
| Examining board members: |
Carlos de Paula Eduardo;
Roberto Ruggiero Braga;
Marcia Martins Marques;
Sheila Cynthia Gouw Soares;
Martha Marques Ferreira Vieira
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| Advisor: | Carlos de Paula Eduardo |
| Abstract | |
The aim of the present study was to determine the correct parameters of the Er,Cr:YSGG laser in the treatment of cervical dentin hypersensitivity. This work was presented in 3 different stages. In the first one, it was evaluated the decrease in dentin permeability of dentinal tubules after Er,Cr:YSGG laser irradiation in radicular surfaces. Ninety premolars were prepared with its crows sectioned, and the roots completely impermeabilized. Two antagonist areas of irradiation were determined as control and experimental. Each surface was conditioned with EDTA 24% (sub-group1) and phosphoric acid 35% (sub-group2) and the selected parameters were: 1)Er:YAG, 60mJ, 2Hz, 4 irradiations of 20sec each, defocused mode; and groups 2 to 9 received irradiation with Er,Cr:YSGG laser, 20Hz, Z6 tip, 600µm diameter, defocus mode, 0% of air and water: 2)Er,Cr:YSGG 0,25W; 3) 0,5W; 4) 0,75W; 5) 1,0W; 6) 1,25W, 7) 1,50W, 8) 2W; 9) 2 W. After irradiation, samples were immersed in a solution of methylene blue for 4 hours, washed for 5 min and included in epoxy resin to allow longitudinal cuts. The images were digitalized and computed worked. Data was statistically analyzed. Although the samples irradiated with Er:YAG showed less microleakage, the sub-group 1 showed differences between the groups, statistically different from groups 3, 6 e 9. The results of the sub-group 2 showed that the mean values of the Er:YAG samples had a tendency to be negative, however, no differences were detected between the groups. In the second stage, cuts from the cervical area were obtained and prepared for scanning electron microscopy to evaluate the superficial morphology. It was observed the partial closure of dentinal tubules after the irradiation with Er:YAG and Er,Cr:YSGG laser in the 0.25 and 0.50W protocols. From the 0.75W until 2W, it was observed the dentinal tubules opened as the energy densities raised. With the results of the in vitro studies, the parameters were selected: G1)control; G2)Er:YAG; G3)Er,Cr:YSGG 0,25W e G4)Er,Cr:YSGG 0,75W. Thirty subjects, who met the entry criteria, were admitted into the study. The assessment method used to quantify sensitivity was the cold air syringe, recorded by the visual analogue scale (VAS), prior to treatment as baseline (Pre-1), immediately before (Pre-2) and immediately after (Post-1) the topical treatment, after 1 week (Post-2) and after 1 month (Post-3). Teeth were assigned to the 4 groups. After the follow-up, data was collected and submitted to statistical analysis for both kinds of stimulus: evaporative (air) and mechanical (probe). For both air and probe it was not observed differences among the Pre-1 and Pre-2 moments, for what it can be concluded that patients were standardized. Analyzing the evaporative stimulus, it can be observed the reduction in the pain level immediately after the treatment; however there was stability in the next values. Group 2 (Er:YAG) showed the least level of pain. Throughout the mechanical stimulus, it was observed that group 4 (Er,Cr:YSGG 0,50W) showed the most pronounced decrease of pain immediately after treatment, however, at the end of the study, the levels of pain increased. Groups 1, 2 e 3 showed reduction of pain, statistically different from the group 4. Based on the results and within the limits of this study, it can be concluded that none of the parameters and lasers studied were capable of eliminate the microleakage and decrease the dentin permeability, however, the Er:YAG and Er,Cr:YSGG 0,25W lasers showed satisfactory results in the three studies performed. (AU) | |