Dentin tubule occlusion by a 38% silver diamine fluoride gel: an in vitro investigation

Objective Silver diamine fluoride (SDF) is effective in treatment of dentin hypersensitivity and caries lesions. However, the non-viscous solution does not easily allow clinicians to control the application area. A 38% SDF experiment gel was compared in vitro to commercial SDF for its ability to penetrate and occlude dentinal tubules. Materials and methods Human root surface dentin specimens were treated with gelled or standard 38% SDF or negative control. Penetration behavior was established by Drop Shape Analysis. Precipitates at the surface and within tubules were analyzed by SEM and EDX after treatment; Results: penetration depths up to 500 µm were observed for both SDF formulations. Both formulations occluded dentinal tubules similarly. Precipitates on the dentin surface and within dentinal tubules were found for both SDF formulations, with a slight tendency for the experimental gel SDF product to be more abundant than the commercially available one. Discussion: behavior of the experimental 38% SDF gel formulation appeared indistinguishable from the commercial 38% SDF product with respect to dentinal tubule penetration and occlusion. Conclusions The experimental 38% SDF gel may be a suitable intervention for the prevention of dentin hypersensitivity.

Effects of Remineralizing Agents Based on Calcium Phosphate, Sodium Phosphate, or Sodium Fluoride on Eroded Cervical Dentin

SUMMARY Objectives: To evaluate the effect of remineralizing agents on collagen matrix pattern, precipitate formation, and dentinal tubule obliteration in eroded cervical dentin. Methods and Materials: One hundred bovine cervical dentin specimens were previously eroded (0.6% hydrochloric acid, pH 2.3, 5 minutes) and then randomized into five groups (n=20): G1, control (without treatment); G2, Desensibilize Nano P (FGM); G3, MI Paste Plus (Recaldent); G4, Regenerate (NR-5); and G5, Desensibilize KF 2% (FGM). These treatments were applied in four sessions with 7-day intervals. During this period, the samples were subjected to an erosive challenge with orange juice (pH 3.8, 5 minutes). The specimens were analyzed by polarized light microscopy with picrosirius red staining, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Results: The G3 showed a higher concentration of type I collagen than G2 and G5 (p<0.05). The G3 showed greater formation of surface precipitates than that of G1 and G5 (p<0.05). In addition, G4 and G5 showed a greater number of open dentinal tubules than that of G3 (p<0.05). Conclusions: Calcium phosphate-based remineralizing agents have shown to be a promising alternative treatment for preventing deleterious effects on the eroded dentin collagen matrix. In addition, they promoted precipitate formation and dentinal tubule obliteration on the eroded dentin.

Hydroxyapatite, a potent agent to reduce dentin hypersensitivity; systematic review

Objective: This study reviews different modes of application of hydroxyapatite for treatment of dentin hypersensitivity via dentinal tubule occlusion. Methods: Literature search was performed using keywords, “hydroxyapatite and dentin hypersensitivity, hydroxyapatite and dentinal tubule occlusion, hydroxyapatite and dentin permeability, dentinal tubule occlusion” on Pubmed, Science Direct and Web of Science, which involved the results of previous 10 years (2009-2018). After screening, 16 studies were included in systematic review. Results: The results of in-vitro studies showed that application of hydroxyapatite caused dentinal tubule occlusion leading to reduction in dentin permeability and reduction in dentin hypersensitivity. Conclusion: Hydroxyapatite has the potential to reduce dentin hypersensitivity via dentinal tubule occlusion within 2-8 weeks. Keywords: Dentin hypersensitivity, Hydroxyapatite, Dentinal tubule occlusion. Continuous...

3D Printed In Vitro Dentin Model to Investigate Occlusive Agents against Tooth Sensitivity

Tooth sensitivity is a painful and very common problem. Often stimulated by consuming hot, cold, sweet, or acidic foods, it is associated with exposed dentin microtubules that are open to dental pulp. One common treatment for tooth hypersensitivity is the application of occlusive particles to block dentin microtubules. The primary methodology currently used to test the penetration and occlusion of particles into dentin pores relies upon dentin discs cut from extracted bovine/human teeth. However, this method is limited due to low accessibility to the raw material. Thus, there is a need for an in vitro dentin model to characterize the effectiveness of occlusive agents. Three-dimensional printing technologies have emerged that make the printing of dentin-like structures possible. This study sought to develop and print a biomaterial ink that mimicked the natural composition and structure of dentin tubules. A formulation of type I collagen (Col), nanocrystalline hydroxyapatite (HAp), and alginate (Alg) was found to be suitable for the 3D printing of scaffolds. The performance of the 3D printed dentin model was compared to the natural dentin disk by image analysis via scanning electron microscopy (SEM), both pre- and post-treatment with occlusive microparticles, to evaluate the degree of dentinal tubule occlusion. The cytocompatibility of printed scaffolds was also confirmed in vitro. This is a promising biomaterial system for the 3D printing of dentin mimics.

Novel Bioactive Adhesive Monomer CMET Promotes Odontogenic Differentiation and Dentin Regeneration

This study aimed to evaluate the in vitro effect of the novel bioactive adhesive monomer CMET, a calcium salt of 4-methacryloxyethyl trimellitate acid (4-MET), on human dental pulp stem cells (hDPSCs) and its capacity to induce tertiary dentin formation in a rat pulp injury model. Aqueous solutions of four tested materials [4-MET, CMET, Ca(OH)2, and mineral trioxide aggregate (MTA)] were added to the culture medium upon confluence, and solvent (dH2O) was used as a control. Cell proliferation was assessed using the Cell Counting Kit-8 assay, and cell differentiation was evaluated by real-time quantitative reverse transcription-polymerase chain reaction. The mineralization-inducing capacity was evaluated using alizarin red S staining and an alkaline phosphatase activity assay. For an in vivo experiment, a mechanical pulp exposure model was prepared on Wistar rats; damaged pulp was capped with Ca(OH)2 or CMET. Cavities were sealed with composite resin, and specimens were assessed after 14 and 28 days. The in vitro results showed that CMET exhibited the lowest cytotoxicity and highest odontogenic differentiation capacity among all tested materials. The favorable outcome on cell mineralization after treatment with CMET involved p38 and c-Jun N-terminal kinases signaling. The nuclear factor kappa B pathway was involved in the CMET-induced mRNA expression of odontogenic markers. Similar to Ca(OH)2, CMET produced a continuous hard tissue bridge at the pulp exposure site, but treatment with only CMET produced a regular dentinal tubule pattern. The findings suggest that (1) the evaluated novel bioactive adhesive monomer provides favorable biocompatibility and odontogenic induction capacity and that (2) CMET might be a very promising adjunctive for pulp-capping materials.

3D Visualization of Dynamic Cellular Reaction of Pulpal CD11c+ Dendritic Cells against Pulpitis in Whole Murine Tooth

In dental pulp, diverse types of cells mediate the dental pulp immunity in a highly complex and dynamic manner. Yet, 3D spatiotemporal changes of various pulpal immune cells dynamically reacting against foreign pathogens during immune response have not been well characterized. It is partly due to the technical difficulty in detailed 3D comprehensive cellular-level observation of dental pulp in whole intact tooth beyond the conventional histological analysis using thin tooth slices. In this work, we validated the optical clearing technique based on modified Murray’s clear as a valuable tool for a comprehensive cellular-level analysis of dental pulp. Utilizing the optical clearing, we successfully achieved a 3D visualization of CD11c+ dendritic cells in the dentin-pulp complex of a whole intact murine tooth. Notably, a small population of unique CD11c+ dendritic cells extending long cytoplasmic processes into the dentinal tubule while located at the dentin-pulp interface like odontoblasts were clearly visualized. 3D visualization of whole murine tooth enabled a reliable observation of these rarely existing cells with a total number less than a couple of tens in one tooth. These CD11c+ dendritic cells with processes in the dentinal tubule were significantly increased in the dental pulpitis model induced by mechanical and chemical irritation. Additionally, the 3D visualization revealed a distinct spatial 3D arrangement of pulpal CD11c+ cells in the pulp into a front-line barrier-like formation in the pulp within 12 h after the irritation. Collectively, these observations demonstrated the unique capability of optical clearing-based comprehensive 3D cellular-level visualization of the whole tooth as an efficient method to analyze 3D spatiotemporal changes of various pulpal cells in normal and pathological conditions.

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

Tubule occlusion and remineralization are considered the two main goals of dentin hypersensitivity treatment. The objective is to assess the ability of dentifrices containing zinc-doped polymeric nanoparticles (NPs) to enduringly occlude the dentinal tubules, reinforcing dentin’s mechanical properties. Fifteen dentin surfaces were acid-treated for dentinal tubule exposure and brushed with (1) distilled water, or with experimental pastes containing (2) 1% of zinc-doped NPs, (3) 5% of zinc-doped NPs, (4) 10% of zinc-doped NPs or (5) Sensodyne®. Topographical and nanomechanical analyses were performed on treated dentin surfaces and after a citric acid challenge. ANOVA and Student–Newman–Keuls tests were used (p < 0.05). The main results indicate that all pastes produced tubule occlusion (100%) and reinforced mechanical properties of intertubular dentin (complex modulus was above 75 GPa). After the citric acid challenge, only those pastes containing zinc-doped NPs were able to maintain tubular occlusion, as specimens treated with Sensodyne® have around 30% of tubules opened. Mechanical properties were maintained for dentin treated with Zn-doped NPs, but in the case of specimens treated with Sensodyne®, complex modulus values were reduced below 50 GPa. It may be concluded that zinc-doped NPs at the lowest tested concentration produced acid-resistant tubular occlusion and increased the mechanical properties of dentin.

“COMPARATIVE EVALUATION OF EFFECT ON DENTINAL TUBULE OCCLUSION BY THREE DIFFERENT DESENSITIZING DENTIFICES: A SEM STUDY”

Introduction: Dentine hypersensitivity (DH) occurs on exposed dentine and is dependent on the patency of dentinal tubules. This study compared the effectiveness of toothpaste containing Strontium Chloride, Novamine, Pro-Arginine in occluding dentine tubules along with comparision of those. Materials and Method: 45 freshly extracted teeth were randomly divided (15 each) into 3 groups: Group 1 15 Teeth treated with toothpaste containing Strontium Chloride. Group 2 15 Teeth treated with toothpaste containing Novamine Group 3 15 Teeth treated with toothpaste containing Pro-Arginine. Each specimen was brushed with the dentifrice slurries and examined under SCM. Result: The mean of occluded dentinal tubules on the dentin surface after brushing with three dentifrices were significant among them Pro-arginine group showed maximum occlusion. Conclusion: The present in vitro SEM study results revealed that: All the experimental agents– Strontium chloride, novamin, Pro- Argenine were effective in occluding dentinal tubules & the percentage (%) of occluded tubules was found to be highest for Pro- Argenine as compared to the other groups. Keywords: SCM, DH