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| Author(s): |
Alessandra Marques Corrêa Afonso
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2006-12-13 |
| Examining board members: |
Regina Guenka Palma Dibb;
Maria Cristina Borsato;
Patricia Petromilli Nordi Sasso Garcia
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| Advisor: | Regina Guenka Palma Dibb |
| Abstract | |
Considering the need of unsatisfactory restoration replacement and the increase of aesthetic restorative materials, the aim of this study was the in vitro assessment the Er:YAG laser capacity of composite resin restoration removal using different frequencies. Thermal side effects caused by laser, times expend during the restoration removal and morphology of resultant cavity were analyzed. The composite resin restoration was done in cavities measuring 2mmx2mmx1mm. The removal was made with Er:YAG laser using different frequencies: 2Hz,4Hz, 6Hz and 10Hz. The results revealed that temperature increase happened at the substrate under the restoration during the removal using the Er:YAG laser. In spite of the results all tested groups showed temperature by 5.6°C, which has been considered safe for the pulp vitality. Another observed aspect at Laser groups\' results was that the increase of temperature was directly proportional to the increase of the repetition rate employed. In relation to the time for removal the experimental groups (in exception of 10Hz laser\'s group) required more time than the high-speed handpiece. The morphological analyses revealed that the experimental groups presented bigger amount of remaining restorative material. At deep walls removal assessment the groups 2Hz and 4Hz presented worst performance. The SEM analyses showed irregularities of resultants cavities of experimental groups what increase proportionally to the repetition rate increase. As the laser group 10Hz also showed ablation of healthy dental tissue. In all groups that the removal was made with Er:YAG laser the remaining restorative material presented melting areas. Therefore it is concluded that the that Er:YAG laser is efficient and safe for composite resin ablation considering the parameters chose in this study. The increase of pulse frequency improved the performance ablation when the time spent and the amount of restorative material removal is analyzed, but it influence was negative when thermal side effects was verified and provided more irregularities in deep wall. Amongst the tested parameters the 250mJ/6Hz was the best and safest to due the minimal thermal alteration caused and acceptable time spent for the procedure. (AU) | |