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Updated: Mar 24, 2026
Author Spotlight: Establishing an Accurate Microhardness Testing Protocol for Craniofacial Tissues
Published on: April 26, 2024
Tooth enamel properties and morphology after microabrasion: an in situ study
Núbia Inocencya Pavesi Pini1, Débora Alves Nunes Leite Lima1, Renato Herman Sundfeld2
1Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
Aim:
This study evaluated the effect of saliva on enamel after microabrasion with different microabrasive compounds under in situ conditions.
Methods:
Enamel/dentin blocks (16 mm2 ) from bovine incisors were divided into nine groups (n = 19): one control group (no treatment), four groups treated with microabrasion using 35% phosphoric acid (H3 PO4 ) + pumice, and the last four groups treated with microabrasion using 6.6% hydrochloric acid (HCl) + silica. The treated groups were subdivided according to the in situ regimen: without salivary exposure, 1 h, 24 h, or 7 days of saliva exposure. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were tested. Scanning electron microscopy (SEM) was used to evaluate enamel morphology. Microhardness data were tested by analysis of variance, and Tukey's and Dunnett's tests (α = 0.05).
Results:
The SMH analysis revealed that all the microabrasion-treated groups presented significantly-reduced SMH values when compared to the control group (P < 0.05). Treatment with HCl + silica was more prone to the effect of saliva than H3 PO4 + pumice, even for CSMH analysis, once the superficial layers reached the same microhardness of that of the control group (P > 0.05). These results were confirmed by SEM, which demonstrated the mineral recovery effect over time.
Conclusion:
Saliva was effective in promoting the rehardening of enamel after microabrasion, mainly for the surfaces treated with HCl + silica.
