Avaliação in vitro e in situ da técnica de microabrasão sobre a microdureza e morfologia do esmalte dental

Author(s)

Núbia Inocencya Pavesi Pini

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2013-03-14

Examining board members

José Roberto Lovadino; Renata Correa Pascotto; Flavio Henrique Baggio Aguiar

• Advisor: Débora Alves Nunes Leite Lima; José Roberto Lovadino

Abstract

Objective: To evaluate, in vitro, the effect of acids used in microabrasion on enamel microhardness, and, in situ, the effects of remineralizing time on enamel surface after microabrasion. Methods: In vitro: Seven groups (n=10) of enamel blocks from bovine incisors were divided in: Experimental groups treated by active/passive application of 35% H3PO4 (E1/E2) or 6.6% HCl (E3/E4); and control groups treated by microabrasion with H3PO4+pumice (C5), HCl+silica (C6), or no treatment (C7). In situ: Nine groups (n=19) of same specimens were divided in according to microabrasion and salivary exposition being 1 control (no treatment) and 4 groups with microabrasion using 35% H3PO4+pumice and 4 groups using 6.6% +silica. One group of each treatment was submitted to 4 frames of salivary exposition, being without exposition and with 1 hour, 24 hours or 7 days of presence on in situ regimen. Surface microhardness (SMH) was evaluated before and after microabrasion, and after salivary exposition (in situ). Cross-sectional microhardness (CSMH) was analyzed after microabrasion (in vitro) and after salivary exposition (in situ). For confocal laser scanning microscopy (CLSM - in vitro) and scanning electron microscopy (SEM - in situ), representative specimens group were selected. Statistical analysis used Proc Mixed, Tukey-Kramer and Dunnet tests (SMH) e ANOVA (subdivided parcels) and Tukey-Kramer tests (CSMH - in situ) (p<0.05). Results: In vitro: For SMH, it was not found statistically differences between the control groups after treatment. Active application resulted in significantly higher microhardness results than passive application, with no difference between acids. For most groups, the CSMH decreased as the depth increased, with differences between the groups treated with microabrasion (C5 and C6) and C7; and between all of experimental groups and C7. A significantly higher mean CSMH result was obtained with active application of H3PO4 compared to HCl. CLSM revealed the conditioning pattern for each group. In situ: For SMH, the groups treated with microabrasion presented reducing in mineral content, with statistical difference in relation to the control and to the initial analysis. The treatment HCl+silica presented lower reduction and were statistically different from the treatment with H3PO4+pumice. After salivary exposition SMH results revealed that surface treated with HCl+silica was more prone to remineralizing effect of saliva, once it was verified since with 1 hour of presence in in situ regimen, with significant differences between the treatments after 7 days of salivary exposition. Just for SMH, the HCl+silica reached values obtained in control group. CSMH analysis showed that 7 days of salivary exposition were efficient in reestablish de values for the outer layers (10 e 25 ?m) of enamel treated with HCl+silica. SEM analysis presented the remineralizing effect in the course of the time. Conclusions: Acids used for enamel microabrasion presented a higher erosive action when solely applicated. Data suggested that enamel surface treated with HCl+silica presented more susceptibility for remineralizing action of saliva than that treated with phosphoric acid and pumice (AU)

• FAPESP's process: 11/04067-7 - Effect of the acids used in the microabrasion technique on superficial and subsuperfical microhardness of enamel
• Grantee: Núbia Inocencya Pavesi Pini
• Support Opportunities: Scholarships in Brazil - Master