Kinetics of fluoride bioavailability in supernatant saliva and salivary sediment

The assessment of the fluoride kinetics in whole saliva as well as in the different salivary phases (supernatant saliva and sediment) is essential for the understanding of fluoride bioavailability.ObjectivesTo assess the fluoride content, provided by sodium fluoride and amine fluoride, in the supernatant saliva and in salivary sediment.MethodsSeven trained volunteers were randomly attributed to 2 groups in a cross-over design and brushed their teeth in the morning for 3 min with a product containing either sodium fluoride or amine fluoride. Saliva was collected before, immediately after tooth brushing and 30, 120, and 360 min later and measured. The samples were centrifuged 10 min at 3024 × g. Fluoride content of the supernatant saliva and of the sediment was analysed using a fluoride sensitive electrode. All subjects repeated the study cycles 2 times, and statistical analyses were made using the nonparametric sign test for related samples, the Wilcoxon–Mann–Whitney-test for independent samples.ResultsThere was a significant increase in fluoride immediately after tooth brushing in both groups in saliva and sediment. The distribution of fluoride between salivary sediment and supernatant saliva (ratio) varied considerably at the different collection times: decreased from 17.87 in baseline samples of saliva to 0.07 immediately and to 0.86 half an hour after tooth brushing in the sodium fluoride group and from 14.33 to 2.85 and to 3.09 in the amine fluoride group. Furthermore after 120 min and after 360 min after tooth brushing the ratio increased from 17.6 to 31.6 in the sodium fluoride group and from 20.5 to 25.76 in the amine fluoride group. No difference was found in the sediment–supernatant saliva ratio between the sodium fluoride and the amine fluoride groups 360 min after tooth brushing.ConclusionFor the assessment of fluoride kinetics in whole saliva it is necessary to pay attention to at least four factors: fluoride formulation, time after fluoride application, fluoride concentration in supernatant saliva and fluoride concentration in salivary sediment. This study was approved by the Ethical Committee of the University of Witten/Herdecke permission 21/2008.     

Mineral distribution of artificial dentinal caries lesions after treatment with fluoride agents in combination with saliva substitutes

Objective: Some saliva substitutes have been shown to demineralize dentine in vitro. This effect is counteracted by the application of various fluorides. In contrast, remineralizing saliva substitutes might be supported by these treatments, depending on the dynamics during remineralization. The aim of this in vitro study was to evaluate the effects of fluoride mouthrinses or gels in combination with de-/remineralizing saliva substitutes on dentinal subsurface lesions. Design: Demineralized bovine dentine specimens were stored either in mineral water [saturation with respect to octacalcium phosphate (S_OCP): 0.7], Glandosane (G, S_OCP: 0.3) or in a modified saliva substitute Saliva natura (SN, S_OCP: 1.9) for five weeks (37 °C). Fluoride agents were applied twice daily for 10 min (n = 15/group): no treatment, Meridol mouthrinse, Elmex sensitive solution, ProSchmelz fluoride gel, Elmex gelée. After storage thin sections were prepared and mineral losses before and after storage were evaluated from microradiographs. Results: Specimens stored in G alone showed significantly higher mineral loss compared to those stored in water, SN or G in combination with any additional treatment (p < 0.05). Storage in SN and treatment with ProSchmelz fluoride gel led to significantly higher remineralization compared to all other groups (p < 0.05) and resulted in distinct mineral gain within the lesion body. Conclusions: Under the in vitro conditions chosen, use of fluoride agents in combination with a demineralizing saliva substitute resulted in reduced mineral loss. Storage in modified Saliva natura in combination with the application of ProSchmelz fluoride gel induced the most pronounced remineralization also of deeper lesion areas.     

FTIR and SEM analysis of CO2 laser irradiated human enamel

ObjectivesConsidering the enamel chemical structure, especially carbonate band, which has a major role in the caries prevention, the objective of the present study was to assess the chemical alterations on the enamel irradiated with CO₂ laser by means of FTIR spectroscopy and SEM analysis.DesignThe enamel surfaces were analysed on a spectrometer for acquisition of the absorption spectrum relative to the chemical composition of the control sample. The irradiation was conducted with a 10.6-μm CO₂ laser (0.55 W, 660 W/cm²). The carbonate absorption band at 1600–1291 cm^?1 as well as the water absorption band at 3793–2652 cm^?1 was measured in each sample after the irradiation. The water band was measured again 24-h after the irradiation. The band area of each chemical compound was delimited, the background was subtracted, and the area under each band was integrated. Each area was normalized by the phosphate band (1190–702 cm^?1).ResultsThere was a statistically significant decrease (p < 0.05) in the water content after irradiation (control: 0.184 ± 0.04; irradiated: 0.078 ± 0.026), which increased again after rehydration (0.145 ± 0.038). The carbonate/phosphate ratio was measured initially (0.112 ± 0.029) and its reduction after irradiation indicated the carbonate loss (0.088 ± 0.014) (p < 0.05).ConclusionThe 10.6-μm CO₂ laser irradiation diminishes the carbonate and water contents in the enamel after irradiation.     

Setting characteristics and cavity adaptation of low-shrinking resin composites

ObjectivesThe aim of this study was to evaluate the setting characteristics of low-shrinking resin composites and examine the possible interactions with curing efficiency and marginal adaptation in dentin cavities.MethodsThe materials tested were Ceram X Mono/CM, Premise/PR, Clearfil Majesty/CM, ELS/EL, and Filtek Silorane/FS. Polymerization shrinkage strain (%S), strain rate (%S_r) and time at maximum strain rate (t_max) were measured using the bonded disk method. Curing efficiency was measured on the top and bottom surfaces of composites with ATR-FTIR spectroscopy. Marginal adaptation was measured in unbonded (%VVF) and bonded (%XVF) specimens by computerized X-ray microtomography (micro-XCT). The % linear length of the interfacial gaps along the cavity margins (%LD) and the maximum gap width (WD_max) were calculated under optical microscopy on sectioned specimens. Statistical analysis was performed with one- and two-way ANOVA, Bonferroni's post hoc test and Pearson's correlation coefficient.ResultsThe %S values ranged from 1.34% (FS) to 2.29% (CX), while %S_r ranged from 0.06%s^?1 (FS) to 0.15%s^?1 (CX). %VVF values extended from 1.9% (FS) to 5.3% (CX) and for %XVF from 1.98% (FS) to 3.35% (CX). The values for %LD ranged from 36.52% (FS) to 81.28% (CX). Linear regression showed strong positive correlation for %S_r and t_max with %VVF (r² = 0.884 and r² = 0.927) and also for %S_r and t_max with %LD (r² = 0.823 and r² = 0.869).Significance%S_r and t_max are more representative than %S in determining the setting pattern of the materials and are strongly correlated to marginal adaptation. The silorane material showed better behavior than the dimethacrylate materials in setting shrinkage and marginal adaptation.     

In vitro dentine remineralization with a potential salivary phosphoprotein homologue

ObjectiveAdvantages of introducing a salivary phosphoprotein homologue under standardized in vitro conditions to simulate the mineral-stabilizing properties of saliva have been proposed. This study longitudinally investigates the effects of casein, incorporated as a potential salivary phosphoprotein homologue in artificial saliva (AS) solutions with/without fluoride (F) on in vitro dentine lesion remineralization.DesignThin sections of bovine root dentine were demineralized and allocated randomly into 6 groups (n = 18) having equivalent mineral loss (ΔZ) after transverse microradiography (TMR). The specimens were remineralized using AS solutions containing casein 0 μg/ml, F 0 ppm (C₀–F₀); casein 0 μg/ml, F 1 ppm (C₀–F₁); casein 10 μg/ml, F 0 ppm (C₁₀–F₀); casein 10 μg/ml, F 1 ppm (C₁₀–F₁); casein 100 μg/ml, F 0 ppm (C₁₀₀–F₀) or casein 100 μg/ml, F 1 ppm (C₁₀₀–F₁) for 28 days with TMR taken every 7 days.ResultsSurface mineral precipitation, evident in group C₀–F_1, was apparently inhibited in groups with casein incorporation. Repeated measures ANOVA with Bonferroni correction revealed higher ΔZ for non-F and non-casein groups than for their counterparts (p < 0.001). Subsequent multiple comparisons showed that mineral gain was higher (p < 0.001) with 10 μg/ml casein than with 100 μg/ml when F was present in the earlier stages of remineralization, with both groups achieving almost complete remineralization after 28 days.ConclusionCasein is a potential salivary phosphoprotein homologue that could be employed for in vitro dentine remineralization studies. Concentration related effects may be clinically significant and thus must be further examined.     

Structure, chemical composition and mechanical properties of coronal cementum in human deciduous molars

ObjectivesIt was hypothesized that the coronal cementum containing collagen forms a weak junction with enamel unlike the well integrated DEJ and CDJ.MethodsThe hypothesis was investigated in two parts: (1) evaluate the structure, chemical composition and mechanical properties of coronal cementum and its junction with enamel using scanning electron microscopy, micro-X-ray computed tomography, and atomic force microscopy. The chemical composition and mechanical properties were determined by evaluating the spatial variations of inorganic (PO₄^3? ν₁ mode at 960 cm^?1) and organic (C–H deformation at 1452 cm^?1; C–H stretch at 2940 cm^?1) contents using Raman microspectroscopy and elastic modulus and hardness values using nanoindentation. (2) Estimate the strength and evaluate the microstructure of coronal cementum interface with enamel using SEM and MicroXCT?.Results and conclusionsCoronal cementum is heterogeneous because it is a combination of laminar acellular afibrillar cementum and acellular extrinsic fiber cementum with relatively higher organic content. It integrates micromechanically via a scallop-like weak interface with enamel unlike the biomechanically efficient DEJ and CDJ and is continuous with primary root cementum. A single tooth could exhibit all three types of cementum enamel junctions; an overlap, butt and a gap depending on the sectioning plane. The elastic modulus of coronal cementum (11.0 ± 5.8 GPa) is significantly lower (p < 0.05; Student's t-test with 95% confidence interval) than primary cementum (15.8 ± 5.3 GPa).     

Prostaglandin E(2) affects osteoblast biology in a dose-dependent manner: An in vitro study

ObjectiveThis study aimed to determine in vitro how exogenous PGE₂ affects the expression of genes in cultured osteoblasts by relative quantitation PCR.DesignCultured osteoblasts were exposed to 10^?3 M, 10^?5 M or 10^?7 M PGE₂ over 5, 10, 15 and 20 days.ResultsRANKL expression was higher after 5 days of exposure (p < 0.05), but thereafter reduced in those treated with the two lower doses of PGE₂ (p < 0.01). RANKL/OPG ratio reported in favour of OPG gene expression and alkaline phosphatase gene expression increased in osteoblasts exposed to the two lower doses of the eicosanoid after 15 days. Conversely, prostaglandin E synthase, a cytokine produced during PGE₂ synthesis, gene expression was significantly reduced at 15 and 20 days (p < 0.01 and 0.05 respectively). The results from this study add to the current knowledge of the mechanisms by which PGE₂ modulates the osteoblast biology in a dose-dependent manner.ConclusionsIt is proposed that PGE₂at a low dose switch osteoblast's biology in favour of bone apposition by: first, inducing a significantly higher OPG gene expression overwhelming RANKL gene expression; second, reducing PGEs synthesis; and third, increasing ALP gene expression. An opposite effect is expected when the concentration of the eicosanoid overpass certain levels.     

Effect of filler particle size and morphology on force/work parameters for stickiness of unset resin-composites

ObjectivesTo investigate the effect of variation in filler particle size and morphology within an unset model series of resin-composites on two stickiness parameters: (1) maximum probe separation-force and (2) work-of-separation. This study was to complement previously reported measurements of composite stickiness in terms of a strain-parameter, ‘peak-height’.Materials and methodsEleven experimental light cured resin-composites were selected. All had the same matrix (Bis-GMA, UDMA and TEGDMA, with 0.33% camphoroquinone) and the same filler volume fraction—56.7%, however filler particles varied in size and shape and were either unimodal or multimodal in size-distribution. Each material was placed in a cylindrical mould (φ = 7 mm × 5 mm depth) held at 26 or 37 °C. The maximum force (F_max, N) and work of probe-separation (W_s, N mm) were measured. A flat-ended stainless-steel probe (φ = 6 mm) was mechanically lowered onto and into the surface of the unset sample, until a compressive force of 1 N was reached, which was held constant for 1 s. Then the probe was moved vertically upward at a constant speed; either 2 or 8 mm/s. The tensile force produced on the probe by the sticky composite was plotted against displacement and the maximum value was identified (F_max). W_s was obtained as the integrated area. Data was analyzed by multivariate ANOVA and multiple pair-wise comparisons using a Tukey post hoc test to establish homogenous subsets (at p = 0.05) for F_max and a Games–Howell was used for W_s.ResultsAs potential measures of stickiness, F_max and W_s showed more coherent trends with fillersize when measured at the lower of the two probe speeds, 2 mm/s. For unimodal resin-composite F_max ranged from 1.04 to 5.11 N and W_s from 0.48 to 11.12 N mm. For the multimodal resin-composite they ranged from 1.64 to 4.13 N and from 2.32 to 8.34 N mm respectively. Temperature increase tended to slightly reduce F_max, although this trend was not consistent. W_s generally increased with temperature.ConclusionFiller particle size and morphology influences F_max and W_s of uncured resin-composite which partly express the handling behaviors of resin-composites.     

Platelet-rich plasma stimulates cytokine expression and alkaline phosphatase activity in osteoblast-derived osteosarcoma cells

ObjectiveThe aim of this study was to investigate the effects of PRP on SAOS-2 cells in terms of cytokine expression, cell activity and oxidative stress.DesignCell line SAOS-2 (1 × 10⁵ cells/mL) were grown in culture medium α-MEM with 10% FBS for 24 h and stimulated (or not) with PRP at concentrations of 3, 10 and 20%, LPS (E. coli, 10 g/mL) and IL-1β (1 mg/mL) for 24 h. The supernatant was collected and analyzed for the expression of cytokines in a panel array, ALP using a commercial kit and NO₂^? with Griess reaction method. Also, the cells were analyzed using Western blot for RANKL and slot blotting for nitrotyrosine expression.ResultThere were no significant differences amongst the groups in terms of NO₂^?, protein nitrotyrosine content and RANKL expression. However, all stimuli increased ALP activity and in case of PRP, it was in a dose-dependent manner (p < 0.001). Also, all stimuli induced an increase in cytokines and chemokines expression, but only PRP promoted an increase of component C5, sICAM-1 and RANTES expression. Whilst IL-1 receptor antagonist (IL-1ra) expression was down-regulated by PRP, both LPS and IL-1β caused up-regulation of this cytokine.ConclusionsPRP can stimulate osteoblast activity and cytokine/chemokine release, as well as indicate some of the mediators that can (and cannot) be involved in this activation.     

The use of calcium-silicate cements to reduce dentine permeability

ObjectiveTo evaluate in vitro the effectiveness of different calcium-silicate (CS) cements specifically designed for dentine permeability reduction.DesignFifty dentine discs were prepared from caries free human molars extracted for surgical reasons. The treatment consisted in applying two different experimental CS cements on dentine surface. Dentine discs treated only with EDTA served as negative control group. Treatment with D-Sense Crystal and Clearfil S³-Bond served as positive control groups. After treatment samples were immersed in artificial saliva. The quantitative changes in the hydraulic conductance (i.e. permeability) through dentinal tubules were quantified using a hydrostatic device working at 6.9 kPa. Dentine permeability was measured immediately after EDTA treatment, 10 min and 1 week after treatment application and immersion of dentine samples in artificial saliva. SEM/EDX analyses were performed to obtain qualitative information on dentine morphology and surface deposits.ResultsThe experimental CS cements reduced dentine permeability immediately after application and also 10 min and 1 week after the immersion of the specimens in artificial saliva. D-Sense Crystal and Clearfil S³-Bond showed higher levels of dentine permeability after 1 week of immersion in artificial saliva.ConclusionsCS cements reduced dentine permeability in vitro even after immersion in artificial saliva, which makes them new valuable candidates for treatment of dentine hypersensitivity in vivo.     

Influence of curing protocol on selected properties of light-curing polymers: Degree of conversion, volume contraction, elastic modulus, and glass transition temperature

ObjectivesThe purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T_g) as measured on a model polymer. It was a further aim to correlate the measured values with each other.MethodsDifferent light-curing protocols were used in order to investigate the influence of energy density (ED), power density (PD), and mode of cure on the properties. The modes of cure were continuous, pulse-delay, and stepped irradiation. DC was measured by Raman micro-spectroscopy. C was determined by pycnometry and a density column. E was measured by a dynamic mechanical analyzer (DMA), and T_g was measured by differential scanning calorimetry (DSC). Data were submitted to two- and three-way ANOVA, and linear regression analyses.ResultsED, PD, and mode of cure influenced DC, C, E, and T_g of the polymer. A significant positive correlation was found between ED and DC (r = 0.58), ED and E (r = 0.51), and ED and T_g (r = 0.44). Taken together, ED and PD were significantly related to DC and E. The regression coefficient was positive for ED and negative for PD. Significant positive correlations were detected between DC and C (r = 0.54), DC and E (r = 0.61), and DC and T_g (r = 0.53). Comparisons between continuous and pulse-delay modes of cure showed significant influence of mode of cure: pulse-delay curing resulted in decreased DC, decreased C, and decreased T_g. Influence of mode of cure, when comparing continuous and step modes of cure, was more ambiguous.SignificanceA complex relationship exists between curing protocol, microstructure of the resin and the investigated properties. The overall performance of a composite is thus indirectly affected by the curing protocol adopted, and the desired reduction of C may be in fact a consequence of the decrease in DC.     

Effect of fluoride toothpaste with nano-sized trimetaphosphate on enamel demineralization: An in vitro study

ObjectiveThis study evaluated the effect of toothpastes containing 1100 ppm F associated or not with micrometric or nano-sized sodium trimetaphosphate (TMP) on enamel demineralization in vitro, using a pH cycling model.DesignBovine enamel blocks (4 mm × 4 mm, n = 96) were randomly allocated into eight groups (n = 12), according to the test toothpastes: Placebo (without fluoride or TMP); 1100 ppm F (1100F); 1100F plus micrometric TMP at concentrations of 1%, 3% or 6%; and 1100F plus nanosized TMP at 1%, 3% or 6%. Blocks were treated 2×/day with slurries of toothpastes and submitted to a pH cycling regimen for five days. Next, final surface hardness (SHf), integrated hardness loss (IHL), differential profile of integrated hardness loss (ΔIHL) and enamel fluoride (F) concentrations were determined. Data were analyzed by ANOVA and Student-Newman-Keuls’ test (p < 0.05).ResultsThe use of 1100F/3%TMPnano led to SHf 30% higher (p < 0.001) and IHL ∼ 80% lower (p < 0.001) when compared to 1100F. This toothpaste also resulted in ∼64% reduction of mineral loss (ΔIHL) when compared to 1100F. Moreover, the addition of nano-sized TMP promoted increases in enamel F uptake of 90%, 160% and 100%, respectively for the concentrations of 1%, 3% and 6%, when compared to 1100F (p < 0.001).ConclusionThe addition of nano-sized TMP at 3% to a conventional toothpaste significantly decreased enamel demineralization when compared to its counterparts without TMP or supplemented with micrometric TMP.     

Airborne microbes in different dental environments in comparison to a public area

ObjectiveThe aim of this study was to investigate quantitatively and qualitatively the airborne microbial load in a multi-chair dental clinic, a normal dental practice and a non-dental public area over a time period of four days and at different time points to estimate the risk of infections during dental surgery.MethodsA multi-chair and a single chair treatment room each were examined in comparison to a non-medical public area over a period of four days. The colony forming units m^?3 (CFUs) were determined and isolated bacteria were characterised by morphological and biochemical analysis, gas chromatography and by 16S rRNA-gene sequencing. In the analyses enterococci were selectively searched for.ResultsThe CFUs in the multi-chair treatment room were between 20 and 1050 CFU m^?3. During treatment the maxima reached were below 800 CFU m^?3. The values in the dental practice were between 200 and 600 CFU m^?3 and remain slightly but not significantly below the levels of the clinic (p > 0.05). In the common area, the CFUs were between 200 and 800 CFU m^?3. The proportion of micrococci was 56.8% in the clinic, 56.07% in the practice and 69.67% in the public area Coagulase-negative staphylococci constituted 35% at the dental clinic, 25% at the bank and 38% at the dental practice. No significant differences amongst the units were detected in the microbial composition of their dental aerosols (p > 0.05).ConclusionAlthough, the bacterial counts in dental room were not significantly higher than the bacterial counts in a public area, the risk from dental clinic might be higher than a public area due to the type of micro-organisms, host susceptibility and the exposure time.     

Assessments of salivary antioxidant activity using electron spin resonance spectroscopy

ObjectiveIn recent years, the function of saliva has been focused on evaluation of general status. The relationship between salivary antioxidant activity and periodontal disease progression is unclear. The aim of this study is to assess the relationship between periodontal disease and salivary antioxidant activity towards various reactive oxygen species (ROS) using electron spin resonance (ESR) technique.MethodsWe demonstrated that whole saliva derived rats or human subjects scavenged ROS such as superoxide (O₂^?) and hydroxyl radical (HO) using ESR spectroscopy with spin trapping agent. In addition, we assessed the relationship between antioxidants activity towards ROS and periodontal index with superoxide dismutase (SOD) activity in human subject saliva.ResultsAntioxidant activity towards O₂^? was increased by Porphyromonas gingivalis (P. gingivalis) infection in rat, although antioxidant activity towards HO was not changed. In human, a strong correlation (r = 0.88, p < 0.01) recognized between salivary antioxidant activity towards O₂^? and probing pocket depth (PPD). In addition, the intensity of salivary antioxidant activity depended on SOD activity level. SOD activity was also correlated with PPD.ConclusionsRat salivary antioxidant activity towards O₂^? was up-regulated by the inflammatory response caused by P. gingivalis infection. Similar response was recognized in human saliva with periodontal index. Additionally, a linear correlation between antioxidant activity towards O₂^? and SOD activity was verified by ESR technique. Therefore, evaluation of the salivary antioxidant activity towards O₂^? might be an effective parameter for the objective assessment of periodontal disease progression.     

Erosive-abrasive tissue loss in dentine under simulated bulimic conditions

ObjectivesThe eroded organic dentine matrix is remarkably resistant to mechanical impacts. Additional brushing abrasion of eroded dentine has only limited influence on tissue loss. Digestive enzymes (e.g., pepsin, trypsin) that can reach the oral cavity during reflux or vomiting can partially degrade the matrix. This degradation may have an influence on both the stability of the matrix against mechanical forces and the susceptibility of eroded dentine to combined chemo-mechanical impacts. Both were investigated in the present study.MethodsDentine samples of four groups were cyclically demineralised (6 × 2 min/day, 9 days) with an HCl-pepsin-solution (pH 1.6, 1.5 mg/ml pepsin) and treated with a trypsin-solution (6 × 10 min/day, 2000 BAEE units/ml) directly afterwards. One group served as control; specimens of three groups were additionally brushed (2 × 15 s/day) directly after the first and last trypsin treatment with forces of 200 g, 300 g, and 400 g. Loss of demineralised and mineralised tissue was determined profilometrically. Additionally, an SEM analysis was performed.ResultsLoss of mineralised tissue (μm, mean ± SD) was: 135.7 ± 10.9 (control), 165.2 ± 30.8 (200 g), 168.0 ± 16.3 (300 g), and 174.9 ± 17.1 (400 g). Tissue loss was increased significantly (p ≤ 0.001) by brushing independently of the force used (n.s. between brushed groups). SEM revealed that in all groups, the matrix was equally thinned through enzymatic activity, but it was still present as a continuous band.ConclusionThe results indicate that brushing of dentine after impact of acid and enzymes resulted in an increased tissue loss; however, the matrix persisted on the surface despite enzymatic treatment and brushing with forces of up to 400 g.     

Bond strength durability of a resin composite on a reinforced ceramic using various repair systems

ObjectivesThis study compared the durability of repair bond strength of a resin composite to a reinforced ceramic after three repair systems.MethodsAlumina-reinforced feldspathic ceramic blocks (Vitadur-α^®) (N = 30) were randomly divided into three groups according to the repair method: PR-Porcelain Repair Kit (Bisco) [etching with 9.5% hydrofluoric acid + silanization + adhesive]; CJ-CoJet Repair Kit (3M ESPE) [(chairside silica coating with 30 μm SiO₂ + silanization (ESPE^®-Sil) + adhesive (Visio?-Bond)]; CL-Clearfil Repair Kit [diamond surface roughening, etching with 40% H₃PO₄ + Clearfil Porcelain Bond Activator + Clearfil SE Bond)]. Resin composite was photo-polymerized on each conditioned ceramic block. Non-trimmed beam specimens were produced for the microtensile bond strength (μTBS) tests. In order to study the hydrolytic durability of the repair methods, the beam specimens obtained from each block were randomly assigned to two conditions. Half of the specimens were tested either immediately after beam production (Dry) or after long-term water storage (37 °C, 150 days) followed by thermocyling (12,000 cycles, 5–55 °C) in a universal testing machine (1 mm/min). Failure types were analyzed under an optical microscope and SEM.ResultsμTBS results were significantly affected by the repair method (p = 0.0001) and the aging conditions (p = 0.0001) (two-way ANOVA, Tukey's test). In dry testing conditions, PR method showed significantly higher (p < 0.001) repair bond strength (19.8 ± 3.8 MPa) than those of CJ and CL (12.4 ± 4.7 and 9.9 ± 2.9, respectively). After long-term water storage and thermocycling, CJ revealed significantly higher results (14.5 ± 3.1 MPa) than those of PR (12.1 ± 2.6 MPa) (p < 0.01) and CL (4.2 ± 2.1 MPa) (p < 0.001). In all groups when tested in dry conditions, cohesive failure in the composite accompanied with adhesive failure at the interface (mixed failures), was frequently observed (76%, 80%, 65% for PR, CJ and CL, respectively). After aging conditions, while the specimens treated with PR and CJ presented primarily mixed failure types (52% and 87%, respectively), CL group presented mainly complete adhesive failures at the interface (70%).SignificanceHydrolytic stability of the repair method based on silica coating and silanization was superior to the other repair strategies for the ceramic tested.     

Salivary levels of antimicrobial peptides Hnp 1-3, Ll-37 and S100 in Behcet's disease

BackgroundOral ulcer is the cardinal clinical sign and increased neutrophilic activity is a part of the pathogenesis in Behcet's disease (BD). Saliva, as a part of the innate immune response, contains antimicrobial peptides (AMPs) that are derived from both oral epithelial cells and neutrophils. The aim of this study was to investigate the associations between salivary levels of AMPs HNP 1-3, LL-37 and S100 and disease course in patients with Behcet's disease (BD).MethodsFifty-three patients with BD and 44 healthy controls (HC) were included in the study. Disease severity score reflecting organ involvement was calculated. Salivary HNP 1-3, LL-37 and S100 levels were measured in unstimulated saliva samples by ELISA.ResultsSalivary HNP 1-3 and S100 levels in BD patients (2715.2 ± 1333.4 μg/ml and 430.6 ± 203.9 ng/ml) were significantly higher compared to HC (1780.6 ± 933.2 μg/ml and 365.3 ± 84.7 ng/ml) (p = 0.000 and p = 0.004, respectively). Although LL-37 levels were also higher in BD than HC (190.9 ± 189.1 vs 143.1 ± 128.9 ng/ml), no significant difference was observed (p = 0.53). Salivary HNP 1-3 and LL-37 levels were associated with the severity of BD (mild disease: 1975.1 ± 1174.2 μg/ml and 115.9 ± 109.4 ng/ml vs severe disease: 2955.7 ± 1305.6 μg/ml and 215.3 ± 203.8 ng/ml, p = 0.020 and p = 0.031, respectively). Salivary LL-37 levels also correlated with the number of monthly oral ulcers (r = 0.5 p = 0.000).ConclusionAn increase in salivary HNP 1-3 and S100 levels might be associated with enhanced local and systemic innate responses in BD.     

Distinct effects of cevimeline and pilocarpine on salivary mechanisms, cardiovascular response and thirst sensation in rats

ObjectiveCevimeline and pilocarpine (muscarinic receptor agonists) are used as sialogogues in xerostomia treatment. It is important to know the different effects on their salivary mechanisms and the side effects. The aim of the present study was to clarify and compare the comprehensive effects of cevimeline to pilocarpine on salivary, cardiovascular and central mechanisms in rats.DesignUnder anaesthesia, whole saliva secretion, parotid blood flow and blood pressure were measured following intra-peritoneal administrations of the sialogogues. In digested parotid cells, intracellular Ca²⁺ concentrations were measured after the sialogogue application. In the conscious condition, changes in angiotensin II-induced water intake were observed after cevimeline administration. In the subfornical organ, which is a thirst-related central nucleus, the effect of cevimeline on the neuronal activity was electrophysiologically investigated.ResultsCevimeline at 80 μmol kg^?1 showed slowly increasing and lasting salivation, a similar blood flow increment in the parotid gland and higher pressor response when compared to pilocarpine at 4 μmol kg^?1. In parotid cells, cevimeline increased the intracellular Ca²⁺ concentration in a similar manner to pilocarpine, but at a higher concentration than pilocarpine. Cevimeline inhibited angiotensin II-induced water intake and neuronal activity in the subfornical organ, which is in contrast to reported effects of pilocarpine.ConclusionsCevimeline activates common salivary mechanism with pilocarpine but has a slower onset of activation, longer duration of salivation and an increased pressor response at higher doses. The anti-dipsogenic effect of cevimeline is due to the inhibitory neuronal effect on the thirst-related central nuclei.     

Effects of blood and saliva contamination on shear bond strength of metal orthodontic brackets and evaluating certain methods for reversing the effect of contamination

The background and purposeContaminations may reduce shear bond strength (SBS) of orthodontic brackets. For reversing such effects, certain surface treatments are suggested. This study was conducted to evaluate (1) effects of saliva and blood contamination on SBS of metal brackets, (2) the efficacy of three surface treatments, while (3) using two adhesives (37% phosphoric acid etchant (Ivoclar/Vivadent) + RMGIC (Fuji Ortho LC), and self-etchant primer (iBonD GI) + composite resin (No-Mix, Dentaurum)).MethodsThe sample was categorized into 12 experimental subgroups (2 contaminations × 3 treatments × 2 adhesives, n = 12 × 10) and 2 control subgroups (n = 2 × 10). Experimental specimens underwent different treatments according to their group. They were incubated (37 °C, 96 h) and thermocycled (3000 cycles, 5–55 °C, dwell time = 30 s). SBS was tested at 1 mm/min crosshead speed.ResultsSEP–composite produced significantly lower SBS rates (P < 0.05) according to Mann–Whitney. ANOVA indicated a significant difference between blood contamination and both control and saliva contamination. According to Wilcoxon signed rank test, comparing with SBS = 7, drying failed to achieve appropriate SBS rates (except drying saliva when using RMGIC). On RMGIC, re-etching and rinsing–drying methods might provide sufficient SBS levels. All treatments (except rinsing–drying saliva contamination) did not produce appropriate SBS levels when using SEP–composite.ConclusionsBlood contamination reduced the SBS much greater than saliva. Using etchant–RMGIC is strongly recommended. Drying may only suffice when RMGIC is used over saliva contamination. The efficacy of re-etching depends on the etchant type. Rinsing–drying may produce appropriate SBS levels.