Enamel permeability and resistance to acid challenges after systemic use of sodium alendronate: a study in rat teeth.

Objectives: To evaluate the enamel resistance and permeability of rat teeth to acid challenges after systemic use of sodium alendronate.
Materials and Methods: Eighteen Wistar rats (36 teeth), aged 36-42 days (200-230 g), were assigned into two groups: alendronate group (n = 20 teeth), which received two weekly doses of 1 mg/kg of alendronate, via gavage; and a non-alendronate group (n = 16 teeth), which received only distilled water. After 60 days, the animals were killed, the maxillary incisors were extracted and used for the artificial induction of the caries lesion (pH cycling regimen) and erosion area (immersion cycles in cola-type soft drink) and for the enamel permeability test (dye penetration). The teeth were divided into alendronate group (n = 10) or non-alendronate group (n = 8) for each test. The quantitative response variables were the percent longitudinal change in Knoop microhardness (%LMC), the enamel carious/erosion lesion area (CELA) and enamel permeability.
Results: Groups were not significantly different (p > 0.05) with regard to the %LMC and enamel permeability (25.58 μm ± 12.73 and 25.40 μm ± 4.6 for the experimental and control groups, respectively). For CELA, it was not observed significant difference (p > 0.05) between the non-alendronate group (24.08 ± 1.36 and 25.22 ± 1.60, for caries and erosion, respectively) and the alendronate group (25.46 ± 1.60 and 25.0 ± 1.26) for caries and erosion, respectively).
Conclusions: Based on the methodological conditions and the presented results of this study, sodium alendronate did not affect the longitudinal microhardness, demineralisation lesion area or permeability of the enamel after acid challenge; therefore, alendronate did not become the enamel of rats more resistant.
Clinical Relevance: The systemic alendronate treatment for 60 days did not change the enamel of rats regarding the susceptibility to acids.