Dentin Permeability Research Articles

Effect of Application of Natural versus Synthetic Desensitizing Agents on Dentin Permeability

Purpose: This in vitro study was established to compare the effect of natural versus synthetic desensitizing agents on dentin permeability. Materials and Methods: Class V cavity preparation was done on the labial surface of 40 premolars for cervical dentin assessment, while for coronal dentin; class I cavity was prepared on the occlusal of 40 premolars. Cavities were etched with phosphoric acid then classified according to treatment either by Bio active glass, Pro-Argin, Moringa extract or untreated (control). The dentin permeability was done using dye penetration test with Evans blue dye. The depth of dye penetration in dentin was examined using stereomicroscope. Results: The results showed that the lowest statistically significant mean depth of dye penetration values were found with Bio active glass followed by Pro-Argin, then Moringa extract. Conclusion: Among the three treatment modalities, Bio active glass and Pro-Argin can be considered as effective materials in the management of hypersensitivity

Analysis of permeability and biological properties of dentin treated with experimental bioactive glasses

ObjectivesTo evaluate obliterating capability and biological performance of desensitizing agents. Methods50 dentin blocks were distributed according to the desensitizing agent used (n = 10): Control (Artificial saliva); Ultra EZ (Ultradent); Desensibilize Nano P (FGM); T5-OH Bioactive Glass (Experimental solution); F18 Bioactive Glass (Experimental solution). Desensitizing treatments were performed for 15 days. In addition, specimens were subjected to acid challenge to simulate oral environment demineralizing conditions. Samples were subjected to permeability analysis before and after desensitizing procedures and acid challenge. Cytotoxicity analysis was performed by using Alamar Blue assay and complemented by total protein quantification by Pierce Bicinchoninic Acid assay at 15 min, 24-h and 48-h time points. Scanning electron microscopy and energy dispersion X-ray spectroscopy were performed for qualitative analysis. Data of dentin permeability was analyzed by two-way repeated measures ANOVA and Tukey's test. For cytotoxicity, Kruskal-Wallis and Newman-Keuls tests. Resultsfor dentin permeability there was no significant difference among desensitizing agents after treatment, but control group presented highest values (0.131 ± 0.076 Lp). After acid challenge, control group maintained highest values (0.044 ± 0.014 Lp) with significant difference to other groups, except for Desensibilize Nano P (0.037 ± 0.019 Lp). For cytotoxicity, there were no significant differences among groups. ConclusionBioglass-based desensitizers caused similar effects to commercially available products, regarding permeability and dentin biological properties. Clinical significanceThere is no gold standard protocol for dentin sensitivity. The study of novel desensitizing agents that can obliterate dentinal tubules in a faster-acting and long-lasting way may help meet this clinical need.

Dentin adhesives application deviations: Effects on permeability and nanoleakage.

The purpose was to evaluate the effect that deviations from the recommended protocol of a two-step etch-and-rinse adhesive system has on permeability and nanoleakage. One hundred and twenty dentin disks were treated with a two-step etch-and-rinse adhesive system, according to the manufacturer's instructions, or using five simulated deviations from the recommended protocol: applying potassium oxalate, reducing the application time of the adhesive, avoiding adhesive drying, aggressively drying the adhesive, and double application of adhesive. Kruskal-Wallis and Tukey's post hoc comparisons were used to evaluate the permeability reduction (α=0.05). Twelve additional dentin disks were prepared for transmission electron microscope (TEM) analysis of nanoleakage. Aggressive drying, adding additional layers of adhesive or using oxalate reduced dentin permeability and yielded a better infiltration of the hybrid layer, whereas reducing the application time or less drying the adhesive did not to reduce dentin permeability, caused extensive nanoleakage, showing immediate compromised dentin sealing.

Performance of a Universal Adhesive on Etched and Non-Etched Surfaces: Changes in Dentin Permeability

Hybridization process for dentin is well known, but remains a difficult challenge as it is dependent on many factors related to dentin substrate, adhesive nature including its solvent. The development of universal adhesives followed the all-in-one concept of existing one-step self-etch adhesives, thus requiring water in their formulation to ionize hydrophilic acid monomers. Most often, carboxylate and/or phosphate groups are their primary functional monomers [1]. Jee, et al. published in 2016 that ethanol molecules penetrate via increasing solvent accessible surfaces induced by the rearrangement of collagen monomers in the gap region [2]. The aim of this study is to evaluate the discrepancy in dentin permeability after application of a universal adhesive used in self-etching (SE) mode or etch and rinse (E&R) mode, by means of hydraulic conductance measurement.

Dentin Permeability and Nanoleakage of Universal Adhesives in Etch-and-rinse vs Self-etch Modes.

This study evaluates the reduction in dentin permeability (P) and the expression of nanoleakage in resin-dentin interfaces made with universal adhesives, comparing the self-etch mode of application with the etch-and-rinse mode of application. To measure dentin P at the baseline and after adhesive polymerization, 80 extracted noncarious human third molars (N=80) were sectioned to obtain 0.7-mm-thick midcoronal dentin disks. The specimens were randomly assigned to 8 groups according to the different adhesive systems and application modes used: Scotchbond Universal (SBU; etch-and-rinse [ER] mode vs self-etch [SE] mode), OptiBond XTR (OPT; etch-and-rinse mode vs self-etch mode), Clearfil Universal Bond Quick (CL; etch-and-rinse mode vs self-etch mode), and Adhese Universal (ADH; etch-and-rinse mode vs self-etch mode). A two-way analysis of variance with interaction was used to evaluate the P reduction differences among the groups (α=0.05). Sixteen additional 0.7-mm-thick dentin disks were similarly prepared and treated, immersed in 50 wt% ammoniacal silver nitrate, and then processed according to conventional methods for analysis under transmission electron microscopy. The differences in P reduction among the adhesives were significant (p=0.029). For OPT and ADH (p=0.0304 and p=0.0120, respectively), the P reduction was higher in the ER mode than in the SE mode. For CL and SBU, no differences in P reduction was observed between the two application modes (p>0.05). All the groups showed some pattern of nanoleakage. No adhesive system completely reduced dentin P. Dentin sealing was higher for OPT and ADH in the ER mode, while for SBU and CL, there was no difference between the two modes. All the adhesive systems showed nanoleakage.

Melatonin-doped polymeric nanoparticles reinforce and remineralize radicular dentin: Morpho-histological, chemical and biomechanical studies

ObjectivesTo investigate the effectiveness of novel polymeric nanoparticles (NPs) doped with melatonin (ML) in reducing dentin permeability and facilitating dentin remineralization after endodontic treatment. MethodsThe effect of undoped NPs and ML-doped NPs (ML-NPs) was tested in radicular dentin, at 24 h and 6 m. A control group without NPs was included. ML liberation was measured. Radicular dentin was assessed for fluid filtration. Dentin remineralization was analyzed by scanning electron microscopy, AFM, Young’s modulus (Ei), Nano DMA-tan delta, and Raman analysis. ResultsML release ranged from 1.85 mg/mL at 24 h to 0.033 mg/mL at 28 d. Both undoped NPs and ML-NPs treated dentin exhibited the lowest microleakage, but samples treated with ML-NPs exhibited hermetically sealed dentinal tubules and extended mineral deposits onto dentin. ML-NPs promoted higher and durable Ei, and functional remineralization at root dentin, generating differences between the values of tan delta among groups and creating zones of stress concentration. Undoped-NPs produced closure of some tubules and porosities at the expense of a relative mineral amorphization. Chemical remineralization based on mineral and organic assessments was higher in samples treated with ML-NPs. When using undoped NPs, precipitation of minerals occurred; however, radicular dentin was not mechanically reinforced but weakened over time. SignificanceApplication of ML-NPs in endodontically treated teeth, previous to the canal filling step, is encouraged due to occlusion of dentinal tubules and the reinforcement of the radicular dentin structure.

Assessment of permeability of eroded dentin after the use of universal, self-etch, and conventional systems.

Dentin hypersensitivity is caused by increased dentinal permeability due to total or partial exposure of dentinal tubules, which in turn can be produced by alterations of dental structures or failure of restorative procedures. The purpose of this in vitro study was to evaluate the efficacy of the application of different kinds of adhesive systems to prevent dentin permeability before and after an erosive challenge. Fifty bovine dentin discs (6x1 mm) were prepared and the specimens were divided into 5 groups (n=10): (SB2) Single Bond 2, (SBU) Universal Single Bond, (CSB) Clearfil SE Bond, (SM) Scotchbond Multipurpose and (C) Control. Hydraulic conductance of dentin was recorded after adhesive application (HC-1) and after erosive challenge (HC-2). Dentin surface images of post-treatment and post-erosive challenge were obtained by scanning electron microscopy (SEM). Data were analyzed using Kruskal Wallis, Mann-Whitney with Bonferroni correction and Wilcoxon tests (p<0.05). Reduction in dentin permeability was observed with the application of adhesive systems (p<0.05). After the erosive challenge, dentin permeability increased for SBU and CSB (p<0.05), while SB2 and SM did not differ in HC-1 or HC-2 (p>0.05). The conventional, self-etching and universal adhesive systems reduce dentinal permeability by more than 80%, and dentin demineralization may contribute to the increased permeability of universal and self-etching systems.

The Stability of Dentin Surface Biobarrier Consisting of Mesoporous Delivery System on Dentinal Tubule Occlusion and Streptococcus Mutans Biofilm Inhibition.

BackgroundThe dentin exposure always leads to dentin hypersensitivity and/or caries. Given the dentin’s tubular structure and low mineralization degree, reestablishing an effective biobarrier to stably protect dentin remains significantly challenging. This study reports a versatile dentin surface biobarrier consisting of a mesoporous silica-based epigallocatechin-3-gallate (EGCG)/nanohydroxyapatite delivery system and evaluates its stability on the dentinal tubule occlusion and the Streptococcus mutans (S. mutans) biofilm inhibition.Materials and MethodsThe mesoporous delivery system was fabricated and characterized. Sensitive dentin discs were prepared and randomly allocated to three groups: 1, control group; 2, casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) group; and 3, the mesoporous delivery system group. The dentin permeability, dentinal tubule occlusion, acid and abrasion resistance, and S. mutans biofilm inhibition were determined for 1 week and 1 month. The in vitro release profiles of EGCG, Ca, and P were also monitored.ResultsThe mesoporous delivery system held the ability to sustainably release EGCG, Ca, and P and could persistently occlude dentinal tubules with acid and abrasion resistance, reduce the dentin permeability, and inhibit the S. mutans biofilm formation for up to 1 month compared with the two other groups. The system provided prolonged stability to combat oral adverse challenges and served as an effective surface biobarrier to protect the exposed dentin.ConclusionThe establishment of the dentin surface biobarrier consisting of a mesoporous delivery system indicates a promising strategy for the prevention and the management of dentin hypersensitivity and caries after enamel loss.

Physicochemical characterization, water sorption and solubility of adhesive systems incorporated with titanium tetrafluoride, and its influence on dentin permeability

Titanium tetrafluoride (TiF4) in an aqueous solution can decrease dentin permeability, but some effects of its incorporation into adhesive systems are not yet known. Therefore, the aim of this study was to characterize the physicochemical, water sorption (WS) and solubility (SL) properties of two adhesive systems (Clearfil SE Bond/C and Scotchbond Universal/S) incorporated with 0.0% (T0), 2.5% (T2) and 4.0% (T4) titanium tetrafluoride (TiF4), and determine dentin permeability (L) after application of these adhesive systems both immediately afterwards (baseline) and after 6 months of storage. The physicochemical analyses of the incorporated solutions were performed based on evaluating particle size (PS), polydispersity index (PDI) by dynamic light scattering, and zeta potential (ZP) by electrophoresis. WS and SL tests followed ISO 4049 standards, and used a 7-day water storage period. The L test was performed by analyzing human dentin discs before and after adhesive system application, and after storage. PS and PDI were higher for CT0 and ST4 (p < 0.0001; ANOVA, Tukey). ZP was lower for CT4, ST2 and ST4 (p < 0.0001; ANOVA, Tukey). A 4.0% TiF4 incorporation showed higher WS (p < 0.05; Mann Whitney, Kruskal Wallis, Dunn). Higher SL was observed for CT0 and ST4 (p < 0.05; Mann Whitney, Kruskal Wallis, Dunn). The L value at baseline was lower for ST4, but was not different from the CT4 groups after storage (p < 0.05; Mann Whitney, Kruskal Wallis, Dunn). It can be concluded that TiF4 affected the colloidal stability of Scotchbond, but did not alter the other properties. The 2.5% TiF4 did not affect the PDI, WS or L of the Clearfil, and can be considered an alternative for reducing hybrid layer degradation.

In Vitro Evaluation of Desensitizing Agents Containing Bioactive Scaffolds of Nanofibers on Dentin Remineralization.

This study evaluated the effect of the incorporation of bioactive nanofibers in desensitizing agents on dentin permeability. Sixty disks of dentin were randomly distributed in four groups (n = 15). Distribution was based on the desensitizing agents, fluoride varnish and self-etching adhesive, and the presence of nanofibers: C (self-etching adhesive Clearfil SE Bond), CN (Clearfil SE Bond with 1% nanofiber), D (Duraphat varnish), and DN (Duraphat varnish with 1% nanofiber). Dentin permeability was determined using hydraulic conductivity. For a qualitative analysis, confocal laser microscopy and scanning electron microscopy were performed. The C group showed the lowest hydraulic conductance (Lp%) (89.33), while the DN group showed the highest Lp% (116.06). No statistical significance was observed in the Lp% values in all groups after the treatment and 6% citric acid challenge (p > 0.239). In the images, the CN group presented a higher superficial and intratubular deposition. In addition, this group presented a more homogeneous dentin surface and wide occlusion of dentinal tubules than the other treatments. Despite there being no statistical differences among the treatments employed, the images showed that the CN group presented a higher surface and intratubular deposition compared to the other treatments, even after the acid challenge.

Comparing the Effectiveness of Different Dentinal Desensitizing Agents: In Vitro Study.

Objectives To evaluate the in vitro effectiveness of desensitizing agents in reducing dentine permeability. Methods The efficacy of desensitizing agents in reducing dentine permeability by occluding dentine tubules was evaluated using a fluid filtration device that conducts at 100 cmH2O (1.4 psi) pressure, and SEM/EDX analyses were evaluated and compared. Forty-two dentine discs (n = 42) of 1 ± 0.2 mm width were obtained from caries-free permanent human molars. Thirty dentine discs (n = 30) were randomly divided into 3 groups (n = 10): Group 1: 2.7% wt. monopotassium-monohydrogen oxalate (Mp-Mh oxalate), Group 2: RMGI XT VAR, and Group 3: LIQ SiO2. Dentine permeability was measured following treatment application after 10 minutes, storage in artificial saliva after 10 minutes and 7 days, and citric acid challenge for 3 minutes. Data were analysed with a repeated measures ANOVA test. Dentine discs (n = 12) were used for SEM/EDX analyses to acquire data on morphological changes on dentine surface and its mineral content after different stages of treatment. Results Desensitizing agents' application on the demineralized dentine discs exhibited significant reduction of permeability compared to its maximum acid permeability values. Mp-Mh oxalate showed a significant reduction in dentine permeability (p < 0.05) when compared to RMGI XT VAR and LIQ SiO2. On SEM/EDX analysis, all the agents formed mineral precipitates that occluded the dentine tubules. Conclusions 2.7% wt. monopotassium-monohydrogen oxalate was significantly effective in reducing dentine permeability compared to RMGI XT VAR and LIQ SiO2.

The Effect of Mesoporous Silica Nanoparticles Desensitizing Slurry Alone or Combined with Calcium Phosphate on Dentin Permeability (An in Scanning Electron Microscope study)

Purpose: Determining the dentinal tubules occlusion and permeability of desensitized dentin after its treatment with (MSN) slurry alone or combined with calcium phosphate (Ca2po4@MSN)versus (NHAp) suspension. Materials and Methods: eighty sound posterior teeth were extracted for orthodontic purpose. Dentin disks of 1 mm thickness were cut perpendicular to the long axis of the teeth at level of 1 mm above the cemento-enamel junction. All samples were treated with 6% citric acid solution for 2 minutes to stimulate sensitive teeth. The samples were divided into four main groups (30 each) according to the material used either Ca+2and PO4@ MSN slurry, slurry of MSN nanoparticles, NHAp suspension and no treatments a control group. These four groups were further subdivided into two groups according to time to after 1 day and after 4 weeks. In random samples from each group, the samples were evaluated for dentinal tubules occlusion using Environmental Scanning Electron Microscope and for dentin permeability. The samples were photographed using Stereomicroscope. Image analysis software was used for indicating degree of occlusion and the depth of dye penetration. The data were analyzed using two-way ANOVA and Turkey’s HSD test. The significance level was set at p ≤ 0.05. Results: There was significant difference observed between Ca2Po4 @MSN nanoparticles and NHAp compared to (MSN alone) group but there was insignificant difference between groups (Ca2Po4@MSN) and (NHAp) in dentinal tubules occlusion and permeability. Conclusion: (Ca2Po4@MSN), MSN alone and NHAp are valuable tools to enhance dentinal tubules occlusion and permeability of desensitizing dentin.

Association of Nd:YAG laser and calcium-phosphate desensitizing pastes on dentin permeability and tubule occlusion.

Objective To evaluate the efficacy of Nd:YAG laser associated with calcium-phosphate desensitizing pastes on dentin permeability and tubule occlusion after erosive/abrasive challenges.Methodology Dentin specimens were exposed to 17% ethylene diamine tetra-acetic acid (EDTA) solution for 5 min and randomly allocated into five groups: G1, control (no treatment); G2, Nd:YAG laser (1 W, 10 Hz, 100 mJ, 85 J/cm2); G3, Laser + TeethmateTM Desensitizer; G4, Laser + Desensibilize Nano P; and G5, Laser+Nupro®. Specimens underwent a 5-day erosion-abrasion cycling. Hydraulic conductance was measured post-EDTA, post-treatment, and post-cycling. Post-treatment and post-cycling permeability (%Lp) was calculated based on post-EDTA measurements, considered 100%. Open dentin tubules (ODT) were calculated at the abovementioned experimental moments using scanning electron microscopy and ImageJ software (n=10). Data were analyzed using two-way repeated measures ANOVA and Tukey’s test (α=0.05).Results G1 presented the highest %Lp post-treatment of all groups (p<0.05), without significantly differences among them. At post-cycling, %Lp significantly decreased in G1, showed no significant differences from post-treatment in G3 and G4, and increased in G2 and G5, without significant differences from G1 (p>0.05). We found no significant differences in ODT among groups (p>0.05) post-EDTA. At post-treatment, treated groups did not differ from each other, but presented lower ODT than G1 (p<0.001). As for post-cycling, we verified no differences among groups (p>0.05), although ODT was significantly lower for all groups when compared to post-EDTA values (p<0.001).Conclusion All treatments effectively reduced dentin permeability and promoted tubule occlusion after application.Combining Nd YAG laser with calcium-phosphate pastes did not improve the laser effect. After erosive-abrasive challenges, treatments presented no differences when compared to the control.

Effect of Laser Activated Sodium Hypochlorite on Sealing Ability of Two Endodontic Sealers Using Stereomicroscope-An In vitro Study

Introduction: The combination of various irrigants, irrigation techniques along with root canal sealers helps in achieving a three-dimensional seal in root canals, which is of clinical relevance. The present in-vitro study aims to assess and compare the efficacy of laser-activated NaOCl on the sealing ability of two endodontic sealers. Materials and Methods: Forty extracted human single-rooted permanent teeth were collected and decoronated 12 mm from their apices. Instrumentation did with an 11 mm working length using Rotary Pro taper files to F3. All the teeth grouped into four (n= 10) based on irrigation protocol and sealer used as follows: Group A1 – Laser activated NaOCl + AH Plus Group A2 – Laser activated NaOCl +nano seal, Group B1 – NaOCl + AH Plus, Group B2 – NaOCl + nano seal. The lateral condensation technique did obturation. Roots stored in freshly prepared 1% methylene blue for 72 hours. The roots were split longitudinally along the long axis using a diamond disc underwater coolant, and markings made at 2, 4, and 6 mm from the apex. The depth of dye penetration and microleakage examined under a stereomicroscope (Magnus) at 30× magnification. Results: Statistical analysis carried out by using the software, statistical package for social sciences [SPSS]. Results represented in the form of minimum, mean, and standard deviation. Conclusion: The laser-activated NaOCl group exhibited better sealing ability than the control group. Among the two sealers, the Bio root RCS sealer showed less leakage &amp; better sealing ability than AH plus Clinical Significance: Increasing the temperature of low concentration sodium hypochlorite solution by the action of the diode laser, not only enhances its immediate tissue dissolution capacity but also increased the dentin permeability by removing the smear layer. Further leading to better adhesion between the root canal sealer and the gutta-percha with the radicular dentin.

Mesoporous calcium silicate nanoparticles for superficial dental tissue reconstruction, in vitro and in vivo.

The underlying dentin could be exposed to a humid atmosphere filled with bacteria if the covering enamel layer is broken because of external chemical and physical conditions. Accordingly, some diseases like bacterial invasion and dentin hypersensitivity often occur, which impact the daily life of patients. The study is aimed at evaluating the occluding effects of mesoporous calcium silicate nanoparticles (MCSNs) on the dentinal tubules in vitro and in vivo, as well as the antibacterial property and drug delivery ability when loaded with chlorhexidine (CHX) in vitro. MCSNs were synthesized according to the standard protocol. After a series of complimentary evaluations in vitro and in vivo, it was found that MCSNs and CHX–MCSNs could continually form apatite-like enamel layers on the exposed dentinal tubules and significantly reduced dentin permeability both in vitro and in vivo. Besides, MCSN and CHX–MCSN possessed low cytotoxicity in vitro, and only mild pulp inflammation was observed in two MCSNs containing groups in vivo. In addition, MCSN loaded with CHX released CHX sustainably and revealed a significant antibacterial effect against E. faecalis in vitro. Therefore, the results suggest that MCSN could be used as a promising biomaterial to occlude the dentinal tubules and carry antibiotics for avoiding further pulp infection.

Assessment of the acid resistance behaviour of dentin tubules occluded by different desensitizers

Aim: To evaluate the efficacy of in-office and home-based products in the prevention of dentinal hypersensitivity on dentin discs.&#x0D; Methodology: Ninety-six dentin disc samples of 1 mm were divided equally into six groups as follows: TeethmateTM, Smartprotect®, novamin®, Arginine calcium carbonate, potassium oxalate with rinse and saline (control). After acid etching, test agents were applied, and eight samples in each group were subjected to citric acid. SEM examination (3000x) and statistical analysis were carried out.&#x0D; Results: Before citric acid challenge, novamin® and teethmate had superiority when compared to others (p&lt;0.001), but there was no a statistical difference between novamin® and teethmate. After citric acid challenge, teethmate and smartprotect showed resistance on occluded tubules. The decreasing in the level of occluded tubules in novamin® group was statistically significant (p&lt;0.05). In-office products including teethmate and smartprotect were found more successful compared to home-based products. Smartprotect resisted against to citric acid (0.506).&#x0D; Conclusion: Novamin® showed a successful occlusion in all tubules before acid challenge whereas; it was the most unsuccessful group after acid challenge when compared to other agents. In-office agents were found to be more successful in reducing dentine permeability than home-care products. In-office agents showed more resistance to acid attacks. Further studies are needed to assess the efficacy of desensitizer agents.&#x0D; How to cite this article:&#x0D; Karayürek F, Arpağ OF. Assessment of the acid resistance behaviour of dentin tubules occluded by different desensitizers. Int Dent Res 2020;10(3):80-9. https://doi.org/10.5577/intdentres.2020.vol10.no3.3&#x0D; &#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Bioactive glass versus Arginine dentifrices on the reduction of dentin permeability and acid tolerance.

ObjectivesTo compare the efficacy of calcium sodium phosphosilicate (CSPS) and arginine dentifrices on dentin permeability and acid tolerance.Material and MethodsSixty dentin discs were randomly assigned into 3 groups, then brushed for 1 min with CSPS, arginine, or fluoride (control) dentifrices. To test acid tolerance, each disc was soaked in 6% citric acid for 1 min. Dentin permeability was measured before, following brushing, and acid challenge. Ten discs per group were similarly treated and evaluated for tubule occlusion following a single dentifrice application, while other five discs per group were employed in an acid tolerance assay.ResultsThe percentage reduction in dentin permeability was 39.26%, 32.27%, and 21.71% in the arginine, CSPS, and control groups, respectively. The differences in dentin permeability reduction between the arginine and CSPS groups following brushing and acid challenge were not significant (p = 0.398 and p = 0.211, respectively). The arginine dentifrice demonstrated a significant reduction in permeability compared with the control (p = 0.011). In addition, the occlusion exhibited by the arginine and CSPS dentifrices was more resistant to acid challenge compared with that of the control (p < 0.001). From SEM analysis, dentinal tubule occlusion was observed after a single application in all groups. Some open dentinal tubules were detected in the test groups, while almost all of the orifices were open in the fluoride group following acid challenge.ConclusionsThere is no significant difference between arginine and CSPS dentifrices in reducing dentin permeability following a single application and acid challenge. Following acid challenge, the reduced permeability generated by arginine and CSPS was more stable compared with the fluoride dentifrice.

Shockwave application enhances the effect of dentin desensitizer

ObjectivesThe purpose of this study was to develop a new device that can improve the effect of desensitizer using shockwaves and to verify its efficacy. MethodsA micro-shockwave generator was developed using a piezoelectric actuator (PIA-1000, piezosystem jena GmbH, Jena, Germany), an Arduino Uno microcontroller (Arduino, Torino, Italy), and a high voltage pulser (HVP-1000, piezosystem jena GmbH) at 700 V (400 A) and 100 μs. The occlusal surfaces of 20 extracted human upper and lower third molars without caries or restoration were reduced to expose the occlusal dentin, and the prepared occlusal surfaces were acid-etched with 32% phosphoric acid to remove the smear layer. The tooth specimens were connected to a fluid flow measurement instrument (nanoFlow, IB SYSTEMS, Seoul, Korea), permeability through dentin via dentinal fluid flow (DFF) was measured for 300 s, and the average DFF rate (Baseline DFF rate) was calculated. A desensitizer (SuperSeal, Phoenix Dental, Fenton, MI, USA) was applied to the acid-etched occlusal dentin surface of 10 randomly selected tooth specimens, left for 10 s, and rubbed with a microbrush for 30 s (Group 1). For the remaining teeth, the desensitizer was applied, and a shockwave (100 μm stroke, 10,000 G) was applied for 10 s (2 shots/s) and rubbed with a microbrush for 30 s (Group 2). After desensitizer application, subsequent DFF was measured for 600 s, and the average DFF rate was calculated (post-application DFF rate). DFF was continuously measured in real-time at 25 ± 0.5 ℃ under a hydrostatic pressure of 25 cm. The percentage reduction in DFF rate after desensitizer application (with or without shockwave) was calculated with respect to baseline DFF rate. Data were analyzed with independent t-test (α = 0.05). ResultsFor all tooth specimens, DFF rate decreased after desensitizer application irrespective of the presence of shockwaves. The percentage reduction in DFF rate of SuperSeal with shockwave (Group 2) was 42.8 ± 19.0%, which was significantly higher than the 26.2 ± 13.6% of the SuperSeal only group (Group 1) (p < 0.05). SignificanceMeasurement of DFF change in real-time shows that shockwaves can help reduce dentin permeability beyond that SuperSeal dentin desensitizer produced alone.

Microhardness and Scanning Electron Microscopic Morphology of Permanent Dentin Following the Application of Iranian and Foreign-Made Desensitizing Toothpastes

Background: This study aimed to assess the microhardness and morphology of permanent dentin following the application of Iranian and foreign-made desensitizing toothpastes. Methods: This in vitro, experimental study evaluated 48 dentin samples prepared of the extracted sound human permanent molars. Dentin samples were randomly divided into three groups (n=16) and subjected to the application of Pooneh Iranian desensitizing toothpaste, Colgate Sensitive Pro- Relief (Poland), and no intervention (negative control). Each dentin sample was then immersed in 5 mL of a demineralizing solution for 10 hours and underwent a demineralization/remineralization cycle (pH cycling) for 14 days. The mean microhardness of the samples was measured at baseline after demineralization and after 14 days. One sample of each toothpaste group was selected for the scanning electron microscopy (SEM) assessment of dentin morphology. Finally, repeated-measures ANOVA was used to analyze the effect of time and type of toothpaste on microhardness using SPSS, version 21. Results: The comparison of the mean microhardness of the control group with experimental groups revealed no significant difference at baseline or after demineralization (P &gt; 0.05) although this difference was significant after 14 days (P &lt; 0.001). The mean microhardness of the two toothpaste groups was not significantly different at different time points (P &gt; 0.05). Finally, the SEM assessment revealed a greater tubular obstruction in Pooneh group after 14 days. Conclusions: Pooneh Iranian-made desensitizing toothpaste was comparable to Colgate Sensitive Pro-Relief foreign-made desensitizing toothpaste in terms of the microhardness of permanent dentin. It even demonstrated superior performance with regard to the obstruction of dentinal tubules.

Effect of Different Application Techniques of Universal Bonding System on Microtensile Bond Strength of Bulk-Fill Composites to Primary and Permanent Dentin.

Objectives:This study aimed to determine the microtensile bond strength (μTBS) of a bulk-fill composite to permanent and primary coronal dentin using a universal adhesive in self-etch and total-etch modes.Materials and Methods:This in-vitro study was performed on 52 occlusal dentinal surfaces of human primary and permanent teeth. The crowns were cut to the gingival level. The 48 prepared dentin sections were randomly assigned to the following groups (n=13): A: Primary/Total-etch, B: Primary/Self-etch, C: Permanent/Total-etch, and D: Permanent/Self-etch. In groups A and C, after etching for 15 seconds, two layers of a universal bonding (Futurabond U) were applied and cured for 10 seconds. All samples were filled with a bulk-fill composite (x-trafil; VOCO) and cured for 40 seconds. The samples were cut to a bar-shaped dentin block with the dimensions of 1×1×1 mm3, and after 10,000 thermocycles, the μTBS test was accomplished at a crosshead speed of 1 mm/minute. The mean and standard deviation (SD) of μTBS were calculated, and the data were analyzed using two-way analysis of variance (ANOVA) and Fisher’s exact test.Results:The mean μTBS was as follows: A: 15.03±2.0279, B: 11.11±2.4423, C: 23.50±4.8165, and D: 16.26±6.3200 MPa. Futurabond U showed a higher μTBS in the total-etch mode (P<0.001). The permanent teeth had greater μTBS than the primary teeth (P<0.001). Similar percentages of failure modes were observed in the total-etch groups but in the self-etch groups, most failures were in the form of adhesive and mixed.Conclusion:Greater μTBS was observed in the permanent teeth with the total-etch technique.