Dentinal Tubule Occlusion Research Articles

Efficacy of remineralizing agents to occlude dentinal tubules in primary teeth subjected to dentin hypersensitivity in vitro: SEM study.

Aim:Comparison of casein phosphopeptides (CPPs) and amorphous calcium phosphate (ACP), tricalcium phosphate, and hydroxyapatite on assessment of dentine tubule occlusion on primary enamel using scanning electron microscope (SEM).Materials and Methods:A total of 20 freshly extracted noncarious primary molars were randomly divided into four groups (A to D) with five sections in each group; group A: negative control, group B: CPP-ACP, group C: tricalcium phosphate, and group D: Hydroxyapatite (HA). To assess tubule occlusion, 20 dentin sections of 2 mm thickness were obtained from cervical third of sound primary molars. Each section were processed to simulate the hypersensitive dentin and the test agents were brushed over the sections with an electric toothbrush and observed under SEM for calculation of the percentage of occluded tubules.Results:Group B and D showed greater percentage of tubule occlusion than group C. Intergroup comparison of tubule occlusion potential of Group B and D was not significant.Conclusion:HA showed significantly higher dentinal tubule occlusion when compared to CPP-ACP and tricalcium phosphate.

An in vitro evaluation of dentinal tubule occlusion using three desensitizing methods: A scanning electron microscopic study.

Aim:The aim is to compare the effects of diode laser, GC tooth mousse, and sodium fluoride (NaF) varnish on dentinal hypersensitivity by scanning electron microscopic (SEM) evaluation.Materials and Methods:Forty extracted human maxillary first premolar teeth were selected to prepare dentin disc of 2 mm thickness. The specimens were divided into four groups of 10 discs each-Group 1: Negative control, Group 2: Diode laser, Group 3: GC tooth mousse, and Group 4: NaF varnish. Diode laser and NaF was exposed on dentin disc for three consecutive days. GC tooth mousse was applied twice a day for 1 week. All the specimens were examined under SEM at a magnification of ×1500. The standardized SEM microphotographs were analyzed according to the scoring criteria.Statistical Analysis:Friedman test with post hoc Wilcoxon sign rank test for pair wise comparison at different time intervals within the group was computed using SPSS version 20. A P < 0.05 was regarded as statistically significant.Results:The results showed that the use of diode laser was able to achieve complete occlusion of dentinal tubules followed by the use of GC tooth mousse and that of NaF varnish while control group showed completely open tubules.Conclusions:Irradiation of dentinal tubules using diode laser could be effective for routine clinical treatment of dentinal hypersensitivity compared to NaF and GC tooth mousse.

Interaction effect of Nd:YAG laser and universal adhesive system for dentin sealing.

BackgroundTo evaluate the influence of the association of the universal adhesive system to different energy densities of the Nd:YAG laser on the hydraulic conductance of dentin. Material and MethodsFifty bovine dentin discs were made. The samples were stratified into four groups (n = 10) according to the treatment performed; SBU- Adper Single Bond Universal (3M ESPE), SBU_60 - SBU associated with the Nd:YAG laser (60mJ, 10Hz, 0.6W - 47.77 J / cm²), SBU_80 - SBU associated with the Nd:YAG laser (80mJ, 10Hz, 0.8 W - 63.69 J / cm2) and C – dentin without treatment (smear layer). Hydraulic conductance measurements were taken 24 hours after the treatments (HC1) and after erosive challenge (HC2). Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX) helped to visualize the dentin after the different treatments. Scheffe and Games-Howell statistical tests were used to analyze hydraulic conductance (α = 0.05). ResultsThe treated dentin (SBU, SBU_60, and SBU_80) reduced HC1 when compared to dentin with smear layer (C) (p< 0.001). The erosive challenge has increased HC2 in SBU_60 and C (p< 0.001), and did not promote a significant difference in SBU_80 and SBU. The SEM / EDX analyzes showed an irregular and semi-permeable barrier on the surfaces of the treated dentin. ConclusionsThe association of universal adhesive with Nd:YAG can be an effective alternative for the occlusion of dentinal tubules, whereas higher energy per pulse Nd:YAG (SBU_80) can increase the resistance to permeability when exposed to the erosive challenge. Key words:Dentin, permeability of dentin, Nd:YAG Laser, adhesives.

A Comparison of Dentin Tubule Occlusion Properties of Dipotassium Oxalate against Potassium Nitrate: An In Vitro Study

The aim of this study is to compare the efficacy of dipotassium oxalate and potassium nitrate to occlude dentinal tubules. This study utilized Parkinson model of longitudinal dentin tubule occluding properties of dentifrices under a 4-day acid challenge. Dentin disks of approximately 1.5 mm thick were sectioned from the crowns of the freshly extracted molars. The disks were randomized into three sets of 15 and treated with dipotassium oxalate, potassium nitrate, or used as a control. The disks were then subjected to a 4-day acid challenge and evaluated by scanning electron microscopy (SEM). On days 1, 2, and 3, dipotassium oxalate showed significant occlusion of dentinal tubules. On day 4, no significant difference was observed between dipotassium oxalate and potassium nitrate. Both test groups showed better occlusion properties in comparison to the control. Through the use of a 4-day acid challenge, this study demonstrates that both agents can indeed occlude dentinal tubules. Initially, dipotassium oxalate does occlude dentinal tubules faster than potassium nitrate. However, at the conclusion of the acid challenge, minimal differences were observed in occlusion rate among the two agents. Further studies should be conducted to determine the efficacy of these two agents. Both dipotassium oxalate and potassium nitrate can help treat patients with dentinal hypersensitivity.

In vitro dentine tubule occlusion by a novel toothpaste containing calcium silicate and sodium phosphate

ObjectivesTo investigate the deposition, formation of hydroxyapatite (HAP) and acid resistance of dentine surfaces following brushing with a toothpaste containing calcium silicate and sodium phosphate (CSSP) and fluoride in vitro. MethodsHuman dentine specimens were brushed with a slurry of CSSP toothpaste followed by exposure to simulated oral fluid (SOF) in two in vitro studies, with a silica-based non-occluding toothpaste as control. The surface and tubule deposits were analysed after 14 cycles with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). In a third study, dentine specimens were additionally exposed to citric acid erosive challenges for 30, 300 or 600 s after 2, 6, 10 and 14 cycles of SOF and either the CSSP toothpaste or a positive control toothpaste containing calcium sodium phosphosilicate and fluoride. The level of tubule occlusion was evaluated using SEM. ResultsThe SEM analyses indicated complete coverage of the dentine surface following 14 cycles of brushing with CSSP toothpaste with no observable patent tubules, in contrast to the non-occluding control toothpaste. The TEM and SAED analyses confirmed the deposited material on the surface and within tubules was HAP. The deposited material from CSSP toothpaste was more acid resistant than the deposited material from the positive control toothpaste at all time points and acid exposure levels (p < 0.05). ConclusionsThe CSSP toothpaste fully occluded dentine tubules and formed the mineral HAP. The dentine deposition on and within dentine tubules was resilient to acid erosive challenges. Clinical significanceA novel toothpaste containing CSSP can form HAP on dentine surfaces and within tubules. The potential of this technology is for a novel approach for the protection of dentine surfaces to acid challenges and the reduction of dentine hypersensitivity.

Fabrication of calcium phosphate composite polymer/SLS-stabilized emulsion-based bioactive gels and their application for dentine tubule occlusion

ObjectivesCalcium phosphate/SLS/P123 composite bioactive gels were prepared to achieve dentine tubule occlusion. MethodsGels containing calcium phosphate particles were prepared in a water-in-oil microemulsion system with a mixture of triblock copolymer pluronic (P123) as a co-surfactant and sodium lauryl sulfate (SLS) as a surfactant in cyclohexane. Subsequently, calcium chloride dihydrate and sodium hydrogen phosphate aqueous solutions were added in a water phase. Finally, slow evaporation of the oil phase at room temperature was performed to produce a hybrid gel. The obtained gels were investigated for their toxicity by the sulforhodamine B (SRB) assay and applied on human dentine specimens to examine their ability to occlude dentine tubules. ResultsThe size and morphology of the calcium phosphate particles embedded in the gel depended on the concentration of P123 and SLS, which were used as a template for mineral precipitation. The prepared calcium phosphate particles (200–500 nm in diameter) with the maximum polymer and surfactant content exhibited spherical shapes. Further, on reducing their content twice and tenfold yields micro-particles with flower-like shapes. These bioactive gels were able to occlude into dentine tubules after 3 days of application with a plugging rate of 79.22% when using the smallest particles. In addition, calcium phosphate nanorods were transformed into dentine tubules with a maximum depth of 6 μm on increasing the amount of gel. ConclusionsThe bioactive gels were effectively used as bioactive fillers to occlude exposed human dentine tubules.

Perbedaan efektifitas penutupan tubulus dentin antara pasta gigi yang mengandung bioaktif glass (novamin) dan strontium chloride

Background : Dentinal hypersensitivity (DH) is a painful clinical condition and is characterized by pain arising from exposed dentin in response to various stimuli. Various treatment modalities are available to treat dentinal hypersensitivity which include at-home and in-office treatment. At home treatment generally consists of a variety of dentrifices containing different constituents like strontium chloride and bioactive glass (Novamin). These agents cause occlusion of dentinal tubules thereby reducing hypersensitivity.Purpose: This study was to evaluate the effects of different desensitizing dentifrices on dentinal tubule occlusion by scanning electron microscopy (SEM) of strontium chloride and bioactive glass (Novamin) pastes in the treatment of dentinehypersensitivity (DH) Methods: sixteen extractedspecimens from bovine incisors teeth with randomized into 2 groups (n=8). The crowns were removed from the root and the crown were sectioned longitudinally into two parts (in a mesiodistaldirection). The cervical toothwere resulting in two samples per tooth.Dentinal tubules were exposedand thesamples provided a 4 mm x 4 mm area of exposed dentinal tubules.Group 1 (treated with strontium chloride), Group 2 (treated with bioactive glass (novamin))After each treatment for seven days, tubule occlusion on dentin were analyzed by scanning electron microscopy (SEM).The data were analyzed using “mann-whitneytest” (p&lt;0.05).Result: Groups bioactive glass (novamin) showed tubule occlusion highest when compared with groups strontium chloride.Conclusion: bioactive glass (novamin) paste showed tubule occlusion highest with strontium chloride

Morphological and chemical effects of in-office and at-home desensitising agents containing sodium fluoride on eroded root dentin

ObjectiveThe aim of this study was to evaluate the morphological and chemical effect of in-office and at-home desensitising agents containing sodium fluoride (NaF) on eroded root dentine in vitro. MethodsFifty bovine dentine samples were pre-eroded and randomised into five groups (n = 10): G1 (Control) - milli-Q water; G2 - fluoride varnish containing NaF 22,500 ppm; G3 - desensitising cream containing NaF 9,000 ppm associated with 20% nanohydroxyapatite; G4 - toothpaste with NaF 5,000 ppm associated to tricalcium phosphate; G5 - toothpaste containing NaF 900 ppm and casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF). The specimens were submitted to erosive challenge for three days. The analyses were performed using non-contact profilometry for volumetric (Sa) and linear roughness (Ra) followed by scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The data were analysed by Kruskal-Wallis and Wilcoxon tests (α = 0.05). ResultsThere was a significant reduction of Ra and Sa for the eroded samples from the G2 and G5 (p < 0.05) after an erosive challenge. The dentine surface topography pattern showed partially or totally occluded dentinal tubules after treatments, except in the control group. The control, G4 and G3 groups showed a reduction in the dentine inorganic content percentage of Ca (Calcium) and P (Phosphorus) minerals. ConclusionThe fluoride varnish and CPP-ACPF toothpaste were able to prevent morphological changes and were the only materials that showed the Ca and P content increased after treatment. These materials may be promising alternatives in the clinical control of dentin erosion.

Dentin Tubule Occlusion Potential of Novel Dentifrices Having Fluoride Containing Bioactive Glass and Zinc Oxide Nanoparticles

Objective: To compare the in vitro potential of dentin tubule occlusion of two novel experimental dentifrices consisting of fluoride containing bioactive glass (BG) with zinc oxide nanoparticles. Materials and Methods: Forty-eight dentin discs (n = 48) were divided into 6 groups (n = 8), based on their brushing dentifrices: Group 1 = artificial saliva (AS; control); Group 2 = fluoride dentifrice (Colgate Palmolive^©, UK); Group 3 = experimental nonactive agent dentifrice; Group 4 = experimental dentifrice with 1.5% BG; Group 5 = experimental dentifrice with 4% BG; and Group 6 = BioMinF^© dentifrice. Postbrushing, the discs were subjected to acidic challenge with 6% wt citric acid (pH = 4.0) for 1 min. Scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) spectroscopy were performed pre- and post-citric acid challenges, and percentages of tubule occlusion assessed. Results: SEM micrographs of group 1 (AS) show no tubule occlusion (0%), whereas those of groups 2 and 3 show partial tubule occlusion (25 to <50% of tubules occluded). The SEM micrographs of dentifrices containing fluoride-BG (groups 4, 5, and 6) show that most of the tubules (>50 and <100%) were occluded. For all the groups (excluding group 1), pre- and post-citric acid challenge values are statistically significant (p < 0.05). EDX analysis reveals the presence of zinc in experimental dentifrices only. Conclusion: The results of novel experimental dentifrices are comparable to those of the BioMinF^©, in terms of tubule occlusion. Dentifrices containing BG could serve as an alternative in dentin sensitivity management.

Toothpaste factors related to dentine tubule occlusion and dentine protection against erosion and abrasion.

To investigate the effect of toothpastes on dentine surface loss and tubule occlusion, and the association of toothpaste-related factors to each of the outcomes. One hundred and sixty human dentine specimens were randomly distributed into 10 groups, according to different toothpastes. The specimens were submitted to artificial saliva (60min), citric acid (3min), and brushing abrasion (25s; totalizing 2min in toothpaste slurries). This was repeated five times and two outcome variables were analyzed: dentine surface loss (dSL; μm) and tubule occlusion by measurement of the total area of open tubules (Area-OT; μm2). Data were analyzed with Kruskal-Wallis and Mann-Whitney tests (α= 0.05); bivariate and multivariate regressions were used to model the association of the chemical (pH, concentration of F-, Ca2+, and PO43- and presence of Sn2+) and physical (% weight of solid particles, particle size, and wettability) factors of the toothpastes to both outcome variables. Toothpastes caused different degrees of dSL and did not differ in Area-OT. All chemical and physical factors, except the presence of Sn2+, were associated with dSL (p< 0.001). Area-OT was associated only with the presence of Sn2+ (p= 0.033). Greater dSL was associated with lower pH, lower concentration of F-, higher concentration of Ca2+ and PO43-, greater % weight of solid particles, smaller particle size, and lesser wettability, whereas tubule occlusion was associated with the presence of Sn2+. Depending on their chemical and physical composition, toothpastes will cause different degrees of dentine tubule occlusion and dentine surface loss. This could, in turn, modulate dentine hypersensitivity.

A comparative evaluation of the effect of four desensitizing agents (strontium chloride, potassium nitrate, pro-argin, bioactive glass) on dentinal occlusion: An ex-vivo SEM study

Aim: The aim of this study was to compare and evaluate the effect of four desensitizing agents (Strontium Chloride, Potassium Nitrate, Pro-Argin, Bioactive Glass) on dentinal occlusion. Materials and Methods: Forty freshly extracted mandibular molars were selected. Dentine discs measuring 6x6x3mm were cut off from cervical 1/3rd of molars. The occlusal surface of each dentine disc was abraded with silicon carbide paper for 1 minute and then immersed in 17% Ethylenediaminetetra-acetic acid for 5 minutes. The specimens were then randomly distributed into 4 groups: Strontium Chloride(G1), Potassium Nitrate(G2), Pro-argin (G3) and Bioactive Glass(G4) and brushed with undiluted tooth paste (1 gm) with colgate actibrush 2 minutes daily for 7 days and stored in artificial saliva. Dentine discs were then analyzed by scanning electron microscope. Results: Data were statistically analyzed by one-way Analysis of Variance (ANOVA) and Tukey’s test. The P value for each group was <0.001 showing that highly significant difference existed among the groups. The Bioactive Glass showed maximum amount of dentinal tubule occlusion among all the groups. The least amount of dentinal tubule occlusion was observed in potassium nitrate. The Energy Dispersive X-ray microanalysis showed highest peaks of Calcium and Phosphorous along with presence of Sodium, Magnesium, Potassium, Carbon, Silicon, Oxygen, Phosphorous, Sulphur, Chlorine, and Fluorine. Conclusion: It was concluded that tooth brushing with dentifrice containing bioactive glass showed maximum amount of dentine tubule occlusion. Clinical Relevance: Dentinal hypersensitivity is a significant clinical problem which can cause considerable concern for patients. Appropriate and combine use of various clinically effective both synthetic and natural desensitizing agents may considerably help to manage the problem.

Inhibitory effect of zinc-containing desensitizer on bacterial biofilm formation and root dentin demineralization.

This study compared the effect of a novel zinc containing, Caredyne Shield (CS), and a fluoroaluminocalciumsilicate-based, Nanoseal (NS) desensitizers on dentin tubule occlusion, inhibition of Streptococcus mutans (S. mutans) biofilm growth, and resistance to bacterial demineralization. Desensitizers were applied to simulated hypersensitive bovine dentin, with distilled water used as a control. S. mutans biofilms were grown on the surface of each specimen in an oral biofilm simulator. CS showed the least bacterial count and water insoluble glucan amount followed by NS. Transverse micro radiography revealed that both CS and NS showed significant reduction in mineral loss and lesion depth of the associated lesion. Scanning electron micrographs showed that the two desensitizers formed obvious depositions on the dentin surfaces, occlusion of tubules and mineral tag formation.

Scanning electron microscopic (SEM) comparison of dentinal tubule occlusion effected by a dentifrice containing NovaMin to that of diode laser (810nm)

Introduction: Dentin hypersensitivity (DH) due to exposed dentine is common among periodontitis patients. The present study compares & evaluates the dentinal tubule occlusion achieved with NovaMin® containing dentifrice & 810 nm diode laser by means of SEM. Materials and Methods: Sixty human premolar dentin discs of 2mm thickness were sanded with wet 600-grit carborundum paper and treated with 17% EDTA. Specimens were allotted to three groups of twenty each: Group 1- Control group, Group 2 –NovaMin® containing dentifrice application, Group 3 - lased with 810 nm diode laser. The proportion of completely occluded tubules and of partially occluded tubules to the total tubules (CO/TT & PO/TT) in the three groups were calculated, and analyzed. Results: Both NovaMin® and Laser demonstrated more complete and partial occlusion of tubules than control group. The incidence of complete occlusion was more with NovaMin®, but that of partial occlusion was similar to diode laser group. Conclusions: Although dentinal tubules occlusion was effective by both NovaMin®& diode laser (810 nm), NovaMin® produced a more complete occlusion of dentinal tubules. Keywords: Dentin hypersensitivity, Diode laser, Dentinal tubule occlusion, Scanning electron microscope.

Effect of a dentifrice containing different particle sizes of hydroxyapatite on dentin tubule occlusion and aqueous Cr (VI) sorption.

BackgroundDentin hypersensitivity is a common negative oral condition that can be treated with dentifrice containing hydroxyapatite (HA). The study evaluated the effect of nano-HA dentifrice on plugging the dentinal tubules for an anti-sensitivity reaction compared to a dentifrice containing common-sized particles. Also, the adsorption capacity of different particle sizes of HA mixed in a dentifrice and which is the optimal particle size was considered.MethodsFourty premolar dentine discs and fourty molar dentine discs were randomly divided into 4 groups: distilled water group, ordinary dentifrice group and 80, 300 nm HA dentifrice group. Each dentin disc was brushed with a dentifrice twice daily at 7600 rpm under 100 g force for 2 mins for 7 consecutive days and divided into two parts, half of the dentin disc was detected by the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), the other half was brushed with distilled water and observed by SEM. One milliliter dentifrice solution (80 nm HA dentifrice, 300 nm HA dentifrice, ordinary dentifrice) was added to 50 ml potassium dichromate solution for 1, 14, and 28 d. The residual Chromium (Cr6+) concentration in the supernatant was measured by the diphenylcarbon phthalocyanine hydrazine method. The elemental constitution in the precipitate was detected by EDS. The Kruskal-Wallis test was used to analyze surface mineralization and different plugging rates of dentinal tubules. The absorption capacity of dentifrices were also evaluated by the Kruskal-Wallis test. ResultsThe plugging rate in the HA dentifrice group was higher than that in the ordinary dentifrice group, and the 80 nm HA dentifrice group showed the best result. The atomic percentages of Ca and P of 80 nm dentifrice group on the surface of dentinal tubules were the highest. The 80 nm HA dentifrice group showed the best adsorption and stable effect of Cr6+, followed by the 300 nm HA dentifrice group. The 300 nm HA dentifrice and the ordinary dentifrice showed desorption phenomenon.ConclusionsThe dentifrice containing HA, especially the 80 nm HA dentifrice, exerts good dentinal tubule occlusion and surface mineralization effect. This dentifrice was also a good adsorbent of Cr6+.

Effect of in-office desensitizers containing calcium and phosphate on dentin permeability and tubule occlusion

ObjectivesTo evaluate the performance of calcium/phosphate desensitizing agents when used for dentin permeability and tubule occlusion. Methods1 mm-thick dentin specimens were immersed in 17% EDTA solution and allocated into 7 groups: 1. Clinpro White Varnish, 2. Clinpro XT Varnish, 3. Teethmate Desensitizer, 4. Desensibilize Nano P, 5. Nupro prophylaxis paste, 6. Duraphat (reference product), and 7. Control (no treatment). After treatment, specimens were submitted to erosion-abrasion cycling for 5 days. Dentin permeability was assessed by hydraulic conductance (n = 10) and environmental scanning electron microscopy ESEM (n = 8) post-EDTA, post- treatment and post-cycling. The percentage of permeability (%Lp) was calculated post-treatment and post-cycling. ImageJ software was used to obtain the number of open dentin tubules (ODT) in the micrographs. Data were statistically analyzed (α = 0.05). ResultsPost-treatment, the %Lp values of all treatments were significantly lower than the control, with Nupro presenting higher %Lp values than Duraphat. All the groups presented significantly lower %Lp values in the post-treatment in comparison with the post-cycling period, except the control. Post-treatment, all groups showed lower numbers of ODTs than the control, except Nupro. Clinpro WV, Clinpro XT, Duraphat and Nano P presented the best results. Post-cycling, there was no significant difference among groups. Clinpro WV and Duraphat presented lower numbers of ODTs post-treatment than they had post-cycling, and the control had a higher number of ODTs post-treatment than they had post-cycling. ConclusionsMost treatments were efficient in reducing both dentin permeability and number of ODTs after treatment; however, none of the products were able to resist the erosive-abrasive challenges.

Effects of Poly(Amidoamine) Dendrimer-Coated Mesoporous Bioactive Glass Nanoparticles on Dentin Remineralization.

Dentin hypersensitivity (DH) is one of the most common clinical conditions usually associated with exposed dentinal surfaces. In this study, we identified the effectiveness of poly(amidoamine) (PAMAM) dendrimer-coated mesoporous bioactive glass nanoparticles (MBN) (PAMAM@MBN) on DH treatment, examining the ion-releasing effect, dentin remineralization, and the occluding effect of dentinal tubules. We synthesized MBN and PAMAM@MBN. After soaking each sample in simulated body fluid (SBF), we observed ion-releasing effects and dentin remineralization effects for 30 days. Also, we prepared 30 premolars to find the ratio of occluded dentinal tubules after applying MBN and PAMAM@MBN, respectively. The results showed that PAMAM did not disrupt the calcium ion-releasing ability or the dentin remineralization of MBN. The PAMAM@MBN showed a better occluding effect for dentinal tubules than that of MBN (p < 0.05). In terms of dentinal tubule occlusion, the gap between MBN was well occluded due to PAMAM. This implies that PAMAM@MBN could be effectively used in dentinal tubule sealing and remineralization.

Effect of Conventional and Acid-modified Casein Phosphopeptide-Amorphous Calcium Phosphate Crèmes on Dentin Permeability Before and After Acid Challenge.

This study investigated the effect of conventional and acidified casein phosphopeptide-amorphous calcium phosphate-containing crèmes (CPP-ACP and ACPP-ACP) on dentin permeability (DP) before and after acid challenge, using a fluid-flow measuring device and scanning electron microscopic (SEM) examination. Fifty dentin discs were prepared from intact human third molars. Each tooth was sectioned 3 mm above and below the cementoenamel junction. The smear layer was removed to expose the dentin and dentinal tubules. For fluid-flow measurement, 20 specimens were used and divided into two groups: (a) CPP-ACP (pH=7) and (b) ACPP-ACP (pH=2). The dentin surfaces were treated with the crème for five minutes daily for two weeks, and then an acid challenge was performed using 6% citric acid. Under simulated pulpal pressure, DP was measured at baseline, five minutes, two weeks, and after acid challenge. The remaining specimens were prepared and examined using SEM to investigate dentinal tubule occlusion. DP was not significantly different between the two CPP-ACP-containing crèmes at any test period (p≥0.05). DP after two weeks or acid challenge was significantly lower than that at five minutes (p<0.05). The results were consistent with the SEM micrographs that presented patent dentinal tubules after a five-minute application and partial blockage of dentinal tubules after the two-week application. The dentinal tubules remained partially occluded after acid challenge. Using conventional and acid-modified CPP-ACP-containing crèmes for two weeks decreased DP and partially occluded the dentinal tubules, which resisted acid challenge.

Novel Activated Microbubbles-based Strategy to Coat Nanoparticles on Root Canal Dentin: Fluid Dynamical Characterization

IntroductionActivated microbubbles (MBs) have the potential to deliver nanoparticles in complex microspaces such as root canals. The objective of the study is to determine the fluid dynamical parameters associated with ultrasonic, sonic, and manual activation of MBs in simulated root canals and to assess the effectiveness of surface coating formed by delivering chitosan nanoparticles using activated MBs within root canals in extracted teeth. MethodsIn stage 1, polydimethylsiloxane models were fabricated to determine the physical effects of MBs agitated manually (MM), sonically (MS), and ultrasonically (MU). Spherical tracer particles were used to visualize and record the fluid motion using an inverted microscope linked to a high-speed camera. The velocity, wall stress, and penetration depth were analyzed at regions of interest. In stage 2, 35 extracted human incisors were divided into 7 groups to evaluate the effectiveness of chitosan nanoparticle delivery using activated MBs (MM, MS, and MU groups). Field emission scanning electron microscopy and energy-dispersive X-rays were used to characterize the nanoparticle coating on root canal dentin and the degree of dentinal tubule occlusion. ResultsIn stage 1, velocity, wall stress, and penetration depth increased significantly in the MB groups compared with the control (P < .01). In stage 2, 70% of the dentin surface was coated, and 65% of the dentinal tubule was occluded with nanoparticle-based coating in the MM, MU, and water ultrasonic groups. Element analysis displayed the presence of dentin smear on the root canal surface for the MU and water ultrasonic groups. ConclusionsActivated MBs enhanced fluid dynamical parameters when compared with water in simulated root canal models. Manual activation of MBs resulted in uniform and significant nanoparticle-based surface coating and tubule blockage in root canal dentin without dentin smear formation.

In vitro evaluation of nanohydroxyapatite synthesized from eggshell waste in occluding dentin tubules.

Dentin hypersensitivity (DH) is a notable painful condition with a negative impact on quality of life. This paper evaluates the occluding abilities of nanohydroxyapatite synthesized from the eggshell waste (EnHAp) in the treatment of DH. EnHAp was synthesized following the wet chemical precipitation method. The purity and phase change were characterized using Fourier transform infrared (FTIR) and X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) were used to observe the morphology of EnHAp. The occluding capabilities were evaluated in vitro using the bovine model. Twenty-five simulated dentin specimens were randomly assigned to five groups: Group 1, untreated; Group 2, eggshell powder alone; Group 3, calcined eggshell powder; Group 4, Colgate Sensitive treated, EnHAp; and Group 5, calcium dihydrogen phosphate (n = 5). The specimens were then subjected to remineralization protocol. The tubule occluding capabilities were observed using FESEM. Analysis of variance was used to analyze the occluding ratio values for all treated specimens. Post hoc test with Bonferroni correction was used to identify the mean differences among the five test groups (α = .05). The FTIR and XRD results confirm that synthesis of EnHAp occurred. HRTEM and FESEM revealed an irregular rod structure with a particle size of 65 nm. The occluding area ratios observed for the EnHAp specimens were significantly higher than other test groups (p < 0.001). The application of EnHAp resulted in an efficient occlusion of dentin tubule. This study suggests that EnHAp is an effective therapy to treat DH.

The effect of different desensitizing strategies on eroded dentin: ex vivo study

Introduction: Conditions like gastroesophageal reflux disease, eating disorders, chronic alcoholism and others promote the contact of gastric acid (HCl) with the oral cavity, resulting in dental erosive lesions [1]. Study hypothesis: there are no differences on the microscopic aspect of eroded superficial and deep dentin after using two different desensitizing toothpastes. The aim of this study is to evaluate microscopic characteristics of eroded superficial and deep dentin when exposed to desensitizing toothpastes. Materials and methods: Sample was obtained from 2 human molars (intact, caries/fracture-free). Each tooth was sectioned in eight parts (4-superficial dentin and 4-deep dentin), giving rise to 16 dentin specimens, randomly assigned in 4 different groups which were divided into 2 subgroups (superficial (s), n = 2 and deep (d), n = 2): Group As and Ad – sound dentin; Group Bs and Bd – Intrinsic erosive challenge (ec) with HCl at pH 2,6 for 60s; Group Cs and Cd – ec and toothbrush, two minutes, twice a day, seven days with stannous fluoride toothpaste; Group Ds and Dd – ec and toothbrush, two minutes, twice a day, seven days with strontium chloride toothpaste. Dentin surface was analyzed with scanning electron microscopy, with magnifications of 1000×, 5000× and 10000×. The study was approved by the Ethics Committee for Health, of Egas Moniz (Reference Number: 523). Results: On superficial dentin: partial and heterogeneous occlusion of the tubules was observed in group Ds; in group Cs there was no tubule occlusion. On deep dentin samples, partial tubule occlusion was observed in groups Cd and Dd, higher on group Dd. Discussion and conclusions: Qualitative analysis of scanning electron microscopy images suggests that Strontium Chloride based toothpastes are capable of promoting a greater dentinal tubule occlusion. The use of Stannous Fluoride toothpaste showed less favorable results, with tubule occlusion occurring only on deep dentin. Figure 1.