Effect of Two Matrix Metalloproteinase Inhibitors on the Color Stability of a Nanofilled Resin Composite

SUMMARY Objectives This in vitro study evaluated the effect of two matrix metalloproteinase (MMP) inhibitors on the color stability of two shades of a nanofilled resin composite. Methods and Materials A total of 60 sound human molars were used in this study. Flat dentin surfaces were obtained by wet grinding the occlusal surfaces. Following acid etching, the molars were divided into three equal groups according to the MMP inhibitor used: Group 1: no inhibitor (control group), group 2: chlorhexidine digluconate based (CHX; Consepsis, Ultradent, South Jordan, UT, USA); group 3: doxycycline based (MTAD; Biopure, Dentsply TulsaDental, Johnson, TN, USA). Adper Single Bond 2 Adhesive (3M ESPE, St Paul, MN, USA) was applied to the treated dentin surfaces. Each group was then subdivided into two equal subgroups of 10 molars each, according to the shade of the resin composite (Filtek Z350 XT, 3M ESPE) used, either B1 or A3. The color was assessed for each subgroup at three times: baseline (after 24 hours); after aging using a total energy of 600 kJ/m2 (Weather-Ometer Ci35A, Atlas Electronic Devices Company, Chicago, IL, USA); and then after a second period of aging, for a total energy of 1200 kJ/m2. Color assessment was carried out using a spectrophotometer. Color change (ΔE) was calculated according to the Commission Internationale de l'Eclairage L*a* b* color scale, comparing each aging period with the baseline color measurement. Data were analyzed using repeated measures analysis of variance and Tukey post hoc test. Results All tested subgroups showed greater discoloration than the clinically acceptable level (3.3). MTAD induced the highest statistically significant color change, followed by CHX, whereas the control groups showed the lowest statistical ΔE values with both tested shades. Shade B1 subgroups showed higher ΔE values when compared with shade A3 subgroups. Conclusion Accelerated aging caused color change in a nanofilled resin composite regardless of MMP inhibitor used. Furthermore, lighter shades showed less color stability when compared with darker shades. </jats:sec

Impact of using nano-hydroxyapatite on postoperative hypersensitivity of two bleaching techniques – randomized controlled clinical trial

Abstract To evaluate the impact of using Nano-hydroxyapatite on post-bleaching hypersensitivity after using two different bleaching techniques. Twenty-eight patients were enrolled in this study according to inclusion and exclusion criteria. The patients were randomly assigned into four groups (n=7). G1; bleaching was performed using photo-catalyzed bleaching technique (Philips, zoom), followed by application of Amorphous Calcium phosphate based desensitizing agent (ACP, Relief ACP). G2; bleaching was performed using chemo-catalyzed bleaching technique (Philips, Dash), followed by application of ACP. G3: bleaching was performed using zoom, followed by application of nano-hydroxyapatite based desensitizing agent (Nano p), G4: bleaching was performed using Dash, followed by application of Nano-hydroxyapatite. Post bleaching hypersensitivity was assessed using “Visual analogue scale”. Hypersensitivity was evaluated after: bleaching immediately, application of the desensitizing agent immediately, 24 hours, 48 hours and after one week. Cases with severe hypersensitivity were relieved immediately after Nano p application, meanwhile in case of ACP, cases with severe pain were relieved after 24 hours after its application. Statistically significant difference was evident with the photo catalyzed group immediately after Nano p application than before its application. Reduction in hypersensitivity by time was evident in both the chemo and photo catalyzed groups. In addition, it was found that after one week, all pain scores disappeared with all tested groups. Nano hydroxyapatite particles have an immediate (just post application) relief effect of severe pain with both used bleaching systems. However, the post bleaching hypersensitivity diminished completely after 1 week, irrespective of the desensitizing agent used. The application of Nano hydroxyapatite paste after bleaching is a valid method for diminishing severe post bleaching hypersensitivity when applied with either a photo or chemo catalyzed bleaching agents.</jats:p

Effect of the Number of Applications of Acetone-based Adhesives on Microtensile Bond Strength and the Hybrid Layer

Clinical Relevance The application technique of total- and self-etching bonding resins affects their bonding strength to dentin.</jats:p

Lead in Egyptian soils: Origin, reactivity and bioavailability measured by stable isotope dilution

© 2017 Elsevier B.V. The current availability of Pb in Egyptian soils and associated plants were studied in 15 locations (n = 159) that had been historically subjected to industrial and automobile Pb emissions. Isotopic dilution with enriched 204Pb was used to estimate the soil Pb labile pool (PbE); results showed that %PbE values were mostly < 25% which is likely due to the alkaline nature of the soils. Nonetheless, lability of Pb was significantly higher in urban and industrial locations indicating greater reactivity of anthropogenic Pb in comparison to geogenic-Pb. A plot of 206Pb/207Pb vs 208Pb/207Pb showed that all soils were aligned close to a virtual binary line between two apparent end member signatures (petrol and geogenic-Pb) suggesting that they are the major sources of Pb in the Egyptian environment. Soils with greater Pb concentrations (urban and industrial locations) displayed a significantly greater ratio of labile petrol-Pb to labile geogenic-Pb in comparison to less-contaminated soils. However, this difference was marginal (± 5%) suggesting that historically emitted petrol-Pb has substantially mixed with geogenic-Pb into a common pool as a result of prolonged contact with soil. The proportion of petrol-Pb in fruits and leaf vegetables was significantly (P < 0.005) greater than that of the associated soils suggesting preferential uptake of the more labile petrol-Pb as opposed to the relatively immobile geogenic-Pb. However, it is also possible that the major source of Pb intake by Egyptian consumers is extraneous Pb dust enriched with petrol Pb rather than systematic Pb via roots uptake