Bovine Dentin Research Articles

Equivalence of human and bovine dentin matrix molecules for dental pulp regeneration: proteomic analysis and biological function

ObjectiveTo compare proteomics and biological function of human dentin matrix molecules (hDMMs) and bovine dentin matrix molecules (bDMMs). DesignDentin powder from human or bovine teeth (n = 4) was demineralized in 10% (v/v) ethylenediaminetetraacetic acid for 7 days. The extracts were dialyzed, lyophilized and proteins were characterized using liquid chromatography-tandem mass spectrometry and shotgun proteomic analysis. To study biological function, mouse-derived undifferentiated dental pulp cells (OD21) were treated with 0.01, 0.1 or 1 μg/mL of hDMMs or bDMMs and proliferation was measured after 24 hours and 48 hours using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell migration was assessed after 24 hours using a Boyden chamber. Alizarin Red S staining was used to evaluate mineral formation. ResultsThere were 307 proteins identified, of which 93 proteins were common to both species. Gene Ontology functional analysis demonstrated similar pattern of biological process in both species which consisted mainly of tissue development and biomineralization. hDMMs and bDMMs both enhanced cell proliferation. After 24 hours, all concentrations of bDMMs promoted cell proliferation (p ≤ 0.05), while hDMMs did not affect proliferation. After 48 hours, groups with 1μg/mL of bDMMs and 0.01μg/mL of hDMMs had increased cell proliferation compared to control (p ≤ 0.0001). All concentrations of hDMMs and bDMMs enhanced cell migration and mineralization (p ≤ 0.0001). ConclusionbDMMs has similar biological functions as hDMMs. Moreover, bDMMs stimulated cell proliferation, migration and differentiation similar to hDMMs.

Hydraulic conductance of dentin after treatment with fluoride toothpaste containing sodium trimetaphosphate microparticles or nanoparticles.

To evaluate the hydraulic conductance of dentin after treatment with fluoride toothpastes containing sodium trimetaphosphate microparticles (TMPmicro) or nanoparticles (TMPnano). The dentinal tubules of bovine dentin blocks (4 × 4 × 1 mm) were unobstructed for determination of the maximum hydraulic conductance of the dentin. The dentin blocks were randomized into four groups (n = 15/group) of toothpastes (placebo, 1100 ppm F, and 1100 with 3% TMPmicro or 3% TMPnano) which were applied for 7 days (2×/day) using a brushing machine. The dentin surface (5/group) was analyzed by scanning electron microscopy. The hydraulic conductance post-treatment was measured in the other ten blocks. Thereafter, the same blocks were immersed in citric acid (pH 3.2) for 1 min, and the conductance was determined again. The data were submitted to 2-way ANOVA repeated measures, followed by the Student-Newman-Keuls test (p < 0.05). The percentage conductance reduction post-treatment for the groups were placebo = 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p < 0.001). After acid attack, the percentage reduction was placebo < 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p < 0.001). The toothpastes containing TMP showed the highest obliteration of dentinal tubules. The addition of TMPmicro to fluoride toothpaste produced a greater reduction in hydraulic conductance when compared with 1100 ppm F toothpaste. The increased capacity of toothpastes containing TMP to reduce hydraulic conductance indicates their potential to reduce symptoms of dentinal hypersensitivity.

Effect of poly (γ-glutamic acid)/tricalcium phosphate (γ-PGA/TCP) composite for dentin remineralization in vitro.

The poly (γ-glutamic acid)/tricalcium phosphate (γ-PGA/TCP) composite was fabricated as a novel biomineralization material function in preventing caries. Demineralized bovine dentin specimens were prepared and randomly divided into 5 groups (i. α-TCP, ⅱ. γ-PGA, ⅲ. γ-PGA/TCP, ⅳ. CPP-ACP, and ⅴ. deionized water) and subjected to 14 days of pH cycling. Remineralization ability was evaluated by lesion depth, mineral loss and microhardness. The morphology of dentin depositions was observed with scanning electron microscope (SEM), the crystal structure was determined by X-ray diffraction (XRD), and the wettability was tested by contact angle measurements. ANOVA revealed specimens treated by γ-PGA/TCP presented the statistically least lesion depth (p<0.01) and mineral loss (p<0.001), and the highest hardness (p<0.001). SEM revealed prominent intra- and inter-tubular precipitates in both γ-PGA and γ-PGA/TCP groups. The XRD patterns of the deposition structures in all groups were similar to those of sound dentin, and the contact angle of water decreased after γ-PGA/TCP treatment.

Preventive effect of experimental polymer-based desensitizers with NaF on demineralization of root dentin -observed using micro-CT.

This study compared the effect of experimental polymer-based desensitizers with NaF and oxalic acid (OA) for preventing root demineralization via observation using micro-CT. Bovine root dentin surfaces were treated with coating materials: no treatment; MS0(+) (MS Coat One®); MS3000(+) (MS Coat®); MS0(-); MS3000(-); MS7000(+/-); fluoride gel (NaF9000). MS; MS polymer, 0-7000; NaF concentrations, (+/-); OA. The specimens were scanned using micro-CT before and after demineralization (pH4.5, 10 h). Following this, the mean mineral loss (ML) after demineralization was calculated, and the specimens were observed under a scanning electron microscope (SEM). The ML values of MS3000(+), MS7000(-), MS7000(+) and NaF9000 were significantly lower than the other groups (p<0.05). Under an SEM, a membrane structure was observed to have formed on the dentin surface in the presence of the MS, fluoride, and OA. The experimental polymer-based desensitizer with oxalic acid and a high concentration of fluoride is effective for preventing root demineralization.

Adhesion strategy and curing mode of a universal adhesive influence the bonding of dual-cured core build-up resin composite to dentin

To evaluate the influence of different adhesion strategies and curing modes of a universal adhesive on shear bond strength (SBS) of a dual-cured core build-up resin composite to bovine dentin. In total, 60 bovine anterior permanent teeth were randomly divided into 6 groups (n = 10/group) according to; 1: Adhesion strategy, 3 groups (self-etching, etch-and-rinse/wet and etch-and-rinse/dry) and 2: Curing mode, 2 groups (light-curing and dual-curing). Subsequent to root and incisal half removal of each tooth, labial enamel was wet ground over #180 SiC papers, and exposed dentin surface was wet ground over #600 SiC paper for 60 s to create a standardized smear layer. Universal adhesive was applied according to its manufacturer instructions and each tooth was then restored with one dual-cured composite cylinder (2mm×2mm). Shear bond strength was run at a crosshead speed of 0.5 mm/min, and failure modes were categorized into: 1- Adhesive, 2- Mixed and 3- Cohesive failures. Statistical analysis was performed using Two-Way ANOVA/Tukey HSD test. The results showed that factor ‘adhesion strategy’ had no statistically significant effect on SBS (p = 0.525). However, factors ‘curing mode’ and ‘adhesion strategy x curing mode’ showed statistically significant effect on SBS (p = 0.020 and p = 0.002 respectively). Mixed failure represented 55%, followed by adhesive failure (43.3%) and the cohesive failure represented 1.7%. It seemed better to apply the universal adhesive used in this study in etch-and-rinse strategy rather than self-etching one, especially when the adhesive was used in light-curing mode. The use of the DC activator seemed to be unnecessary.

Inhibitory effect of Salvadora persica extract (Miswak) on collagen degradation in demineralized dentin: In vitro study

Background/purposeRoot dentin is vulnerable to acid attack, suggesting a higher risk of demineralization than coronal enamel. This study aimed to evaluate the inhibitory effect of Miswak extract on collagen degradation of demineralized dentin lesion. Materials and methodsDemineralized bovine root dentin specimens were treated for 1 h by 20% Miswak extract and 0.12% Chlorehexidine (CHX) as a positive control group, and then subjected to collagenolytic attack (clostridium histolyticum 0.5 CDU/mL, 16 h). These cyclic treatments were repeated for 3 days. After the cyclic treatment, the images of the specimens were captured with a light microscope and the lesion depth of degraded collagen layer of all specimens was measured. The mean lesion depth was calculated and compared between the groups using descriptive and One-way ANOVA followed by Post hoc Tukey's tests. Significant level was set at p < 0.05. ResultsThe mean lesion depth of CHX (28.6 ± 3.37 μm) had the least value, followed by Miswak (37.5 ± 4.01 μm) then the control (78.4 ± 18.43 μm) group. There was a significant difference in the mean lesion depth among the three groups (p = 0.000). ConclusionMiswak aqueous extract from S. persica was found to preserve the dentin collagen matrix from collagenase enzyme. This could be due to the organic compounds like flavonoids, saponins, alkaloids, tannins, and others which have been reported in literature. Present finding suggests that Miswak might play a positive effect in dentin caries prevention.

Repair Surface Conditioning Measures Affect Enamel and Dentin Bond Strength.

Contamination of enamel and dentin with repair surface conditioning measures should be avoided. Objectives: To analyze whether the contamination with different repair conditioning measures impairs the adhesive performance of a universal adhesive applied in etch-and-rinse mode (ER) or self-etch mode (SE).Methods and Materials: Bovine enamel and dentin surfaces (each subgroup n=16) were bonded with a universal adhesive in ER or SE after contamination with different repair conditioning measures (sandblasting, silica coating, hydrofluoric acid etching, self-etching ceramic primer). In half of the groups, sand-blasting, silica coating, and hydrofluoric acid etching was followed by the use of a universal primer. If the universal adhesive was applied in ER, contamination was performed either before or after phosphoric acid etching. If the universal adhesive was applied in SE, bonding was performed after contamination. In the control groups, no contamination was simulated. Shear bond strength (SBS) and failure modes of composite buildups were determined after thermal cycling (10,000 cycles, 5°C-55°C). Statistical analysis was performed using analyses of variance, Weibull statistics, and χ2 tests (p<0.05).Results: In ER, sandblasting and silica coating significantly reduced SBS (control: enamel =25.7±4.2 MPa; dentin = 22.0±5.3 MPa) only when performed after phosphoric acid etching. Contamination with hydrofluoric acid impaired SBS on enamel but not on dentin. The self-etching ceramic primer reduced SBS, but not significantly. The contamination with the universal primer had no significant effect. In SE, all repair conditioning measures except the universal primer reduced SBS (control: enamel = 20.3±5.5 MPa; dentin = 23.0±4.0 MPa).Conclusion: Contamination of enamel and dentin by repair conditioning measures potentially affects bond strength.

Effect of dentine cutting efficiency on the lateral force created by torque-controlled rotary instruments.

To study the impact of dentine cutting efficiency of rotary instruments on the lateral force they create when instrumenting simulated root canals in bovine dentine. Lateral cutting efficiency of austenitic files (ProTaper Universal) was compared to that of counterparts of a reported identical geometrical design with a martensite phase component (ProTaper Gold) in bovine dentine disks (n=6). Instrument shapes were studied using digital microscopy. The intracanal lateral force exerted by the two systems in simulated premolars (n=9) made from bovine incisor roots containing a standardized narrow root canal of 16mm length was monitored using a testing apparatus equipped with a torque-controlled endodontic motor/handpiece. Data were compared using parametric statistics, alpha error=0.05. The geometrical design of the two systems under investigation was found to be identical. The martensitic nickel-titanium rotary files had a significantly (t-test, P<0.05) higher lateral cutting efficiency than austenitic counterparts. This difference, however, did not impact the lateral force that was created when instrumenting simulated premolar root canals. Furthermore, lateral force peaks were generated with the progressively tapered instruments under investigation towards the full working length. Even though a glide path was prepared, the first instrument in the full-length sequence (S1) created the highest lateral force (anova/Tukey's HSD, P<0.05). The current experimental set-up allows the study of the lateral force generated during root canal instrumentation. This force was not influenced by the dentine cutting efficiency of the instruments under investigation, but rather by their geometrical design.

Influence of de-remineralization process on chemical, microstructural, and mechanical properties of human and bovine dentin.

This study compared the chemical composition, microstructural, and mechanical properties of human and bovine dentin subjected to a demineralization/remineralization process. Human and bovine incisors were sectioned to obtain 120 coronal dentin beams (6 × 1 × 1mm3) that were randomly allocated into 4 subgroups (n = 15) according to the time of treatment (sound, pH-cycling for 3, 7, and 14days). Three-point bending mechanical test, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric (TG), and X-ray diffraction (XRD) techniques were employed to characterize the dentin samples. Regarding chemical composition at the molecular level, bovine sound dentin showed significantly lower values in organic and inorganic content (collagen cross-linking, CO3/amide I, and CO3/PO4; p = 0.002, p = 0.026, and p = 0.002, respectively) compared to humans. Employing XRD analyses, a higher mineral crystallinity in human dentin than in bovines at 7 and 14days (p = 0.003 and p = 0.009, respectively) was observed. At the end of the pH-cycling, CI (ATR-FTIR) and CO3/PO4 ratios (ATR-FTIR) increased, while CO3/amide I (ATR-FTIR), PO4/amide I (ATR-FTIR), and %mineral (TG) ratios decreased. The extension by compression values increased over exposure time with significant differences between dentin types (p < 0.001, in all cases), reaching higher values in bovine dentin. However, flexural strength (MPa) did not show differences between groups. We also observed the correlation between compositional variables (i.e., PO4/amide I, CI, and %mineral) and the extension by compression. Human and bovine dentin are different in terms of microstructure, chemical composition, mechanical strength, and in their response to the demineralization/remineralization process by pH-cycling. These dissimilarities may constitute a potential limitation when replacing human teeth with bovines in in vitro studies.

¿Puede la protección de la superficie prevenir la pérdida de dureza en las superficies de dentina y resina compuesta expuestas a erosión?

Objective: This study investigated the effect of endogenous erosion on the microhardness of dentine and a nanofilled composite resin. Procedures for preventing erosion were also studied. Materials and Methods: 90 bovine dentine specimens were divided into three groups in accordance with the method for preventing: negative control, topical application of fluoride and resin-modified glass ionomer varnish. 120 composite resin specimens were distributed into four groups, which also included a resin sealant, among the preventive procedures. Specimens were then randomly divided into three sub-groups according to the exposure to simulate gastric acid solution and subsequent remineralization: negative control, 9 and 18 cycles. Surface analysis was carried out by measuring the Knoop hardness. The data obtained were statistically analyzed using 2-way ANOVA and Tukey test. Result: The mean hardness of dentine and of the composite specimens resin exhibited lower hardness after 18 cycles. However, the resin-modified glass ionomer varnish resulted in greater values compared to the other preventive procedures. Conclusion: A resin-modified glass ionomer varnish seems to be a promising method for minimizing the damage caused by endogenous acid, but its protection can be reduced depending on the intensity of the erosive challenge.

Antibacterial and remineralizing nanocomposite inhibit root caries biofilms and protect root dentin hardness at the margins

ObjectivesSenior patients have a high incidence of tooth root caries. The objectives of this study were to: (1) develop a bioactive composite with calcium (Ca) and phosphate (P) ion-release and antibacterial capabilities via nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM); (2) inhibit root biofilms of Streptococcus mutans, Lactobacillus acidophilus and Candida albicans in a biofilm-based recurrent root caries model to protect root dentin hardness under biofilms for the first time. MethodsFive groups were tested: (1) Heliomolar nanocomposite (Commercial control); (2) Experimental composite control (0% NACP, 0% DMAHDM); (3) Remineralizing composite (30% NACP); (4) Antibacterial composite (3% DMAHDM); (5) Remineralizing and antibacterial composite (NACP + DMAHDM). Colony-forming units (CFU), lactic acid and polysaccharide of biofilms were evaluated. Demineralization of bovine root dentin with restorations was induced via multi-species biofilms, and root dentin hardness was measured. ResultsAdding NACP and DMAHDM into composite did not compromise the mechanical properties (p > 0.05). Biofilm lactic acid, polysaccharides and CFU were greatly reduced via DMAHDM (p < 0.05). Ca and P ion releases were substantially increased at cariogenic low pH. With multi-species biofilm acid attack, root dentin hardness (GPa) decreased to 0.12 ± 0.03 for Commercial control, and 0.11 ± 0.03 for Experimental control. Root dentin hardness was 0.20 ± 0.04 for NACP group, 0.21 ± 0.04 for DMAHDM group, and 0.30 ± 0.03 for NACP + DMAHDM group which was more than 2-fold that of control groups (p < 0.05). ConclusionsThe novel NACP + DMAHDM nanocomposite had strong antibacterial effects and Ca and P ion release. When tested in a multi-species recurrent root caries model, NACP + DMAHDM nanocomposite substantially reduced root dentin demineralization and protected dentin hardness around the restorations under biofilms. Therefore, this novel bioactive composite is promising to inhibit root caries and protect tooth structures.

Development and calibration of biochemical models for testing dental restorations

Currently, resin composites are the most popular materials for dental restoration in clinical practice. Although the properties of such materials have been improved significantly, together with better clinical techniques used for their placement, early restoration failure still occurs too frequently. As clinical studies take years to complete, and new resin composites are being produced at ever increasing pace, laboratory assessment using accelerated but representative tests is necessary. The main types of failure in resin-composite restoration are tooth/restoration fracture and secondary caries, which are caused by a combination of mechanical and biochemical challenges. In this study, a biofilm model (S. mutans) and a chemical model (lactic-acid buffer) for producing artificial caries in bovine dentin are developed and calibrated against in situ data. Using a power law relationship between the demineralization depth and challenge duration, scale factors that convert the in vitro durations to the equivalent clinical durations are determined for different pH values for each model. The scale factors will allow the synchronization of biochemical and mechanical challenges in terms of their rates of action to potentially test resin-composite restoration in an accelerated but clinically representative manner. Statement of significanceAlthough the properties of resin composites for dental restoration have been improved significantly, early restoration failure still occurs too frequently. As clinical studies take years to complete, accelerated laboratory testing is necessary. Resin-composite restoration fail mainly through fracture and secondary caries, caused by a combination of mechanical and biochemical challenges. In this study, a biofilm and a chemical model for producing artificial caries in bovine dentin are calibrated against in situ data. Using a power law relationship between demineralization depth and challenge duration, scale factors are determined for different pH for each model. The scale factors will allow the synchronization of biochemical and mechanical challenges in testing resin-composite restoration in an accelerated but clinically representative manner.

Conjugate of chitosan nanoparticles with chloroaluminium phthalocyanine: Synthesis, characterization and photoinactivation of Streptococcus mutans biofilm.

Antimicrobial photodynamic therapy (aPDT) using chloroaluminium phthalocyanine (ClAlPc) has high oxidative power allowing for the control of biofilms, especially when the photosensitizer is administered in an appropriate release vehicle. This study aimed to develop/characterize the ClAlPc encapsulated in chitosan nanoparticles (CSNPs), and evaluate its antimicrobial properties against S. mutans biofilms. CSNPs were prepared by ion gelation, and characterization studies included particle size, polydispersion index (IPd), zeta potential, accelerated stability, absorption spectrum and ClAlPc quantification. The S. mutans biofilms were formed in bovine dentin blocks at 37 °C for 48 h under microaerophilic conditions. 8 μM ClAlPc was combined with a diode laser (InGaAlP) at 660 nm and 100 J/cm2. The aPDT toxicity was verified by dark phototoxicity. The antimicrobial activity was verified by CFU/mL and biofilm was analyzed by scanning electron microscopy (SEM). The number of viable bacteria was analyzed by ANOVA and Tukey HSD tests (α = 0.05). The characterization revealed that the ClAlPc nanoparticles were found in nanometer-scale with adequate photophysical and photochemical properties. The aPDT mediated by ClAlPc + CSNPs nanoconjugate showed a significant reduction in the viability of S. mutans (1log10 CFU/mL) compared to the negative control (PBS, p < 0.05). The aPDT mediated by ClAlPc was similar to PBS (p > 0.05). SEM revealed change in biofilm morphology following the treatment of bacteria with aPDT ClAlPc + CSNPs. Cells were arranged as single or in shorted chains. Irregular shapes of S. mutans were found. ClAlPc nanoparticles are considered stable and aPDT mediated by ClAlPc + CSNPs nanoconjugate was effective against S. mutans biofilm.

The influence of centrifugation and inoculation time on the number, distribution, and viability of intratubular bacteria and surface biofilm in deciduous and permanent bovine dentin

The present study aimed to assess the influence of centrifugation and inoculation time on the number, distribution, and viability of intratubular bacteria and surface monospecies E. faecalis biofilm. Materials and methodsForty-four semicylindrical specimens cut from primary (n = 22) and permanent (n = 22) bovine teeth were randomly assigned to the experimental groups. Teeth of each type were inoculated with E. faecalis with and without centrifugation for 1 and 14 days. The number, localization, viability of bacteria and depth of their penetration were assessed with bacterial culturing of dentin shavings, scanning electron microscopy (SEM) and confocal laser electron microscopy (CLSM). Three-way ANOVA with post-hoc Tukey test were used to assess the influence of different experimental setups on dentin infection. ResultsSevere dentin infection was observed in permanent and deciduous teeth after centrifugation and 1-day incubation: bacteria reached the full length of dentinal tubules and colony-forming units were too numerous to count. The volume of green fluorescence didn’t differ significantly in permanent teeth compared with deciduous (p = 1.0). After 1-day stationary inoculation, small number of cultivable bacteria and few viable bacteria in dentinal tubules were found in both groups. After 14-day stationary inoculation, the dentin infection according to CLSM was deeper in deciduous teeth compared with permanent (p = 0.006 and p = 0.019 for centrifugation and stationary inoculation, respectively). ConclusionThe most even and dense dentin infection was observed in primary and permanent bovine teeth after centrifugation and 1-day inoculation, and in deciduous teeth after 14-day stationary inoculation.

Re- and demineralization characteristics of dentin depending on fluoride application and baseline characteristics in situ

ObjectivesThe aim of this double-blinded, randomized, cross-over in situ study was to evaluate the re- and demineralization characteristics of sound dentin as well as highly and lowly demineralized dentin after the application of different fluoride concentrations. MethodsIn each of four experimental legs of four weeks 20 participants wore intraoral mandibular appliances containing two (highly demineralized [EH]) bovine enamel and four (lowly and highly demineralized [DL,DH]) bovine dentin specimens (n = 480). Each specimen included one sound (ST) and one demineralized lesion area (DT). The four randomly allocated treatments included the following dentifrices: fluoride-free, zinc-carbonate-nano-hydroxyapatite [nHA0], 0 ppm F− [negative control,NaF0], 1100 ppm F− as NaF [standard therapy,NaF1100] and 5000 ppm F− as NaF [positive control,NaF5000]. Differences in integrated mineral loss (ΔΔZ) and lesion depth (ΔLD) were calculated between values before and after the in situ period using transversal microradiography. ResultsAfter the in situ period specimens of nHA0 and NaF0 showed signs of demineralization, indicated by significantly lower ΔZ&LD values for EH and DL (only nHA0)(p ≤ 0.028), whereas specimens of NaF1100 and NaF5000 showed signs of remineralization, indicated by significantly higher ΔZ values for EH (only NaF5000), DL and DH (p ≤ 0.012). The correlation between ΔΔZDT/ΔΔZST and F− was moderate for EH(rDT = 0.497;rST = 0.463) and DL(rDT = 0.575;rST = 0.598) and strong for DH(rDH = 0.700;rST = 0.611)(p < 0.001). No significant differences for ΔΔZDT/ΔΔZST were observed between nHA0 and NaF0(p ≥ 0.333;ANCOVA). ConclusionThe present in situ model was capable to reveal a fluoride dose-response on sound, lowly and highly demineralized dentin and also enamel specimens. Furthermore, both fluoride-free dentifrices, one containing nanohydroxyapatite, did not hamper demineralization. Clinical SignificanceThe present in situ model was capable to reveal a fluoride dose-response on dentin similar to the anticipated clinical efficacy. Highly demineralized specimens seem to be recommendable for measuring anti-caries effects on dentin in situ. Furthermore both fluoride-free dentifrices, one containing nanohydroxyapatite, did not hamper demineralization.The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00011653).

Effectiveness of Thymoquinone and Fluoridated Bioactive Glass/Nano-Oxide Contained Dentifrices on Abrasion and Dentine Tubules Occlusion: An Ex Vivo Study.

Objectives Dentin hypersensitivity (DH) is mainly due to the loss and replenishment of minerals from tooth structure, where the lost minerals can be rehabilitated with a biomimetic approach. The objectives were to determine the relative dentin abrasivity (RDA) of experimental (EXT) dentifrices and to determine the efficacy to occlude dentinal tubules. Materials and Methods Experimental dentifrices contained nano-fluoridated bioactive glass (n-FBG: 1.5 wt.% [EXT-A], 2.5 wt.% [EXT-B], and 3.5 wt.% [EXT-C]), nano-zinc oxide (n-ZnO), and thymoquinone as active agents. Bovine dentin blocks were subjected to brushing treatments as per groups, that is, distilled water; commercial dentifrice (control, CT); EXT toothpastes; and EXT-D without active agents. Samples were tested for three-dimensional (3D) abrasion analysis according to ISO-11609:2010 (International Organization for Standardization [ISO]). The roughness average (Ra), RDA, surface topography, and elemental compositions were investigated. Statistical Analysis One-way analysis of variance (ANOVA) with post-hoc Tukey’s and Tamhane’s test was performed for characterizations using Statistical Package for the Social Sciences (SPSS) version 21. The result was considered significant with p -value ≤ 0.05. Results Comparisons of Ra differed significantly between all groups with p < 0.05 except CT and EXT-A. The RDA values of EXT-A, EXT-B, and EXT-C were calculated as 74.04, 84.26, and 116.24, respectively, which were well within the acceptable limit set by international standards. All n-FBG containing dentifrices demonstrated uniform occlusion of dentinal tubules; however, highly concentrated EXT dentifrices showed more occlusion. Conclusions Acceptable range of RDA and superior occlusion of tubules by novel dentifrices suggest that it may be recommended for treating DH.

Bonding performance and mechanical properties of flowable bulk-fill and traditional composites in high c-factor cavity models

Objectives:The aim of this study is to evaluate bond strength (BS), shrinkage stress (SS), flexural strength (FS), and elastic modulus (E) of three flowable bulk fill in comparison with conventional composites.Materials and Methods:Three bulk fill (Filtek Bulk Fill Flow, Surefil SDR, X-tra Base) and three conventional composites (Filtek Z250 XT, Grandioso, Dentsply TPH3) were used. For BS, conical cavities (n = 10) were prepared in bovine dentine and restored with materials and were analyzed through push-out test in a universal testing machine (UTM). For FS/EM, 60 (n = 10) bar specimens (7 mm × 2 mm × 1 mm) were prepared and evaluated with a UTM. SS was measured in UTM coupled to an extensometer (n = 5). The data were statistically evaluated using one-way ANOVA/Tukey tests (P < 0.05).Results:Conventional composites showed higher E when compared to bulk-fill composites. Regarding FS, they showed similar results, except for (XBF) Xtra Bulk Fill that was inferior. SS and BS of bulk-fill composites were significantly lower and higher than conventional composites, respectively, except for XBF, which showed similar BS to conventional ones.Conclusions:Flowable bulk-fill composites, except XBF, showed higher BS, lower SS, similar FS, and lower E when compared to conventional ones.

An investigation in the remineralization and acid resistant characteristics of nanohydroxyapatite produced from eggshell waste via mechanochemistry.

This study focuses on the properties of nanohydroxyapatite (nHAp) in terms of remineralization and acid resistance. The nHAp were produced from waste eggshells via the mechanochemistry process. The characterization was based on Fourier Transform Spectroscopy, X-ray diffraction, Field Scanning Electron Microscope (FESEM), and High-Resolution Electron Microscope to determine the surface morphology of the nHAp. The acid and remineralization properties were evaluated using bovine enamel and dentine models (n = 5) while the buffering properties against acids were studied using a pH meter. The biocompatibility of the produce nHAp was assessed in vitro against NIH 3T3. The XRD and FTIR results confirm that nHAp were successfully produced from eggshell waste after 5 h of milling. The HRTEM reveals a semi-sphere morphology with an average dimension of 9 to 20 nm. The buffering test suggests that nHAp were highly effective in neutralizing common dietary acids. Also, the nHAp exhibits outstanding remineralization and occluding properties. The cytotoxicity assay suggests that the nHAp had a low toxicity. The study concludes that using eggshell waste to produce nHAp will help in waste management and at the same time, provide valuable biomaterial for the treatment of tooth sensitivity.

Effect of Salvadora persica Extract (Miswak) on the Dentinal Tubules of Sound Root Dentin: Scanning Electron Microscope Study.

Background/Purpose:Root dentin is vulnerable to a higher risk of demineralization than coronal enamel. This study aimed to evaluate the effect of miswak extract on the dentinal tubules of sound root dentin.Materials and Methods:Twenty bovine root dentin blocks, approximately 2 mm × 3 mm × 3 mm (width × length × depth) in dimensions, were prepared from freshly extracted sound bovine incisors. The sample was divided into two groups: control and miswak group. The control group had sound root dentin block and the miswak test group was treated with miswak extract 20% for 24 h. The two groups of all specimens were subjected to ultrasonication for 10 min. Scanning electron microscope images were analyzed for surface typography.Results:Fifty percent of the control group had surface particles (SPs), while the other 50% had no SPs. For the dentinal tubules, all (100%) the control group had a mixture of opened and partially opened dentinal tubules. On the other hand, for the miswak group, all (100%) the sample had SPs and blocked dentinal tubules.Conclusion:Miswak showed total blocking of the dentinal tubules compared to the control group. This might indicate that miswak has a role in reducing dentinal hypersensitivity of exposed root dentin.

Effect of collagenase enzyme on collagen degradation at different time intervals

Background/Purpose: To compare the effect of collagenase enzyme on collagen degradation at different concentrations and time intervals. Materials and Methods: Forty bovine root dentin blocks were demineralized with acetate buffer (0.1M pH 4.3) for 3 days at 37°C. The specimens were divided into one control (n = 10) and three experimental groups (n = 10 each) allocated for collagenous challenge by 1U/ml collagenous enzymes for different time interval; 6, 9, and 16 h. The 16 h (1.0 U/ml) (n = 10) was further compared with 16 h (0.5 U/ml) group (n = 10). After the cyclic treatment, the images of the specimens were captured with a light microscope and the lesion depth (LD) of degraded collagen layer was measured. Mean LD was calculated and compared between the groups using descriptive, one-way ANOVA, post hoc Tukey's tests, and independent sample t-test. Significant level was set at P < 0.05. Results: The effect of 1 U/mL collagenase enzyme significantly increased with time (P < 0.000). The mean LD at 6 h was (27.8 μm ± 3.8), followed by 9 h (48.1 μm ± 8.6), followed by 16 h (74.2 μm ± 9.8). No significant difference in mean LD was found between 0.5 U/mL (78.4 μm ± 18.4) and 1 U/mL (74.2 μm ± 9.8) at 16 h (P = 0.556). Conclusion: The effect of collagenase enzyme significantly increases with time. However, there were no differences in LD among the different collagenase enzyme concentrations.