Novel Pastes Containing Polymeric Nanoparticles for Dentin Hypersensitivity Treatment: An In Vitro Study

Dentine tubule occlusion effect of hydrolyzed casein in a bioactive glass-based dental desensitizing gel

OBJECTIVES

The effectiveness of three different groups of polyethylene glycol (PEG)-based gels containing powders on dentin hypersensitivity (DH) treatment were assessed and compared with Actimins® as commercial reference group.

METHODS

Hydroxyapatite nanorods (nHA) and sol-gel-derived 45S5 bioglass (SGD 45S5) powders were synthesized through hydrothermal and sol-gel methods, respectively. First, 25 demineralized dentin disks were divided into five groups. Then, the prepared gels based on 45S5 bioglass with and without hydrolyzed casein (HC) as experimental, nHA gel and Actimins® as positive and commercial reference groups were applied twice a day on disks by a micro applicator. To mimic the oral environment, treated disks were immersed in artificial saliva in a water bath at 37 °C for 7 days. However, in the negative control group, no agent was applied on the samples. FE-SEM, EDS, AFM, and XRD were performed to assess tubule occlusion. One-way ANOVA test was used for statistical analysis and p*<0.05 was set as the significance level.

RESULTS

The nHA with an average aspect ratio of 2.77 and the SGD 45S5 powders with a polygonal morphology and the average size of 48.64±11.38 µm were synthesized. After treatment, tubule occlusion in HC-SGD 45S5 and nHA gels were shown to be higher than other groups. The root mean square roughness (Rrms) of the above-mentioned gels showed to be 121.54±9.25 nm, and 312.6 ± 9 nm, respectively.

CONCLUSION

The nHA containing group exhibited the highest tubule occlusion efficiency (i.e., tubule diameter of 0.92±0.32 µm) with a superior mineral precipitation. HC as a novel material demonstrates to be potentially beneficial in DH treatment.

CLINICAL SIGNIFICANCE

DH as a common issue may be reduced or eliminated by occlusion of patent dentinal tubules. There are various types of desensitizing agents capable of controlling the DH by the occlusion of patent dentinal tubules. The desensitizing gels developed in this study showed to be promising for clinical and home-use applications.

Resin-based materials to control human dentin permeability under erosive conditions in vitro: A hydraulic conductance, confocal microscopy and FTIR study

OBJECTIVES

To characterize the behavior of three different polymeric agents before and after an erosive challenge on dentin permeability, to analyze their degradation in both conditions, and to analyze their degree of conversion (DC).

METHODS

The permeability of human dentin disks (1.0 ± 0.2 mm) was measured with smear layer, after its removal, after treatment (LpTreat) with Gluma Desensitizer, PRG Barrier Coat (PBC) or Icon infiltrant (n = 11/group) and after exposure to citric acid (LpEro) (6%, pH 2.1, 1 min). The specimens were analyzed under a Laser Scanning Confocal Microscope (n = 2/group) and the products' DC were calculated. Data were subjected to 2-way repeated measures ANOVA and post-hoc Bonferroni (permeability analysis), to paired t-test (for specimens treated with Icon) and to t-test (DC analysis) (α < 0.05).

RESULTS

Icon showed the lowest LpTreat and LpEro values, while PBC and Gluma did not differ from each other under these conditions. Icon and PBC showed LpEro similar to a dentin with smear layer. Under the Laser Scanning Confocal Microscope, more deposits were noticeable on dentin after treating with PBC. Gluma presented the deepest penetration in dentin. The DC of PBC was the highest.

SIGNIFICANCE

Icon caused the highest reduction on permeability values, followed by PBC and Gluma. PBC generated more deposits covering dentin and seemed to be more efficient after an erosive challenge. The association of a polymeric resin with inorganic ion-releasing fillers seem to be a great strategy to manage dentin hypersensitivity under erosive conditions.