Do Different Tooth Bleaching-Remineralizing Regimens Affect the Bleaching Effectiveness and Enamel Microhardness In Vitro?

Objective

Tooth bleaching may negatively affect the enamel surface properties, such as reduction in hardness values, and remineralizing agents can reverse these effects. This study evaluated the effect of remineralizing agents before, during, and after the bleaching process on enamel's whitening effectiveness and microhardness.

Methods and Materials

The initial color of 104 bovine incisors after immersion in tea solution was recorded, and then, the teeth were randomly divided into eight groups (n = 13). Group 1 (NC) was considered the control with no treatment, and Group 2 (B) was bleached with 40% hydrogen peroxide gel. The 3% fluorohydroxyapatite (FHA) and 2% sodium fluoride (NaF) were applied before (FHA/B, NaF/B), during (FHA + B, NaF + B) and after (B/FHA, B/NaF) the bleaching process in other groups. The final color and microhardness in three depths of 20-30, 50-60, and 100-120 µm were measured. Data were analyzed using Shapiro-Wilk, one-way ANOVA, Tukey, Games Howell, repeated measurement, and LSD tests.

Results

The FHA + B presented the lowest ΔE, significantly lower than other groups, except B/FHA. The ΔE in B/FHA was significantly lower than B/NaF. The bleaching significantly reduced the enamel hardness in three depths. The highest microhardness values were reported for B/NaF and NaF + B, which have no noticeable difference with NC, while FHA/B showed the lowest hardness in three depths, which was significantly lower than NC.

Conclusion

The application of NaF before, during, and after the bleaching improved the microhardness of bleached enamel as the unbleached one with no adverse effect on whitening effectiveness.

In Vitro Study of the Leishmanicidal Activity of Perovskia Abrotanoides Terpenoid-Rich Fractions Against Leishmania Major (MRHO/IR/75/ER)

Background

Cutaneous leishmaniasis (CL) is an ulcerative skin disease caused by some species of the genus Leishmania. Evidence shows that Perovskia abrotanoides is an important herbal medicine against Leishmania. This study was conducted to investigate the killing effect of terpenoid-rich fractions on promastigotes of L. major (MRHO/IR/75/ER).

Material and Method

The eluates of reverse phased medium pressure liquid chromatography (RP-MPLC) of the extract were subjected to thin-layer chromatography (TLC) and categorized into six final fractions. Primary proton nuclear magnetic resonance (H-NMR) spectroscopy confirmed fractions' nature. Fractions 4, 5, and 6 (F4, F5, F6) were identified as terpenoid-rich content. Two concentrations of 50 and 100 μg/ml were prepared to test leishmanicidal activity. Followed by treating promastigotes of L. major by the fractions in incubation times of 12, 24, and 48 hours, their viability was determined using a cell proliferation MTS ((3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay.

Result

F4, F5, and F6 showed significant killing activity on promastigotes of L. major in a concentration-dependent manner. The viability of promastigotes was significantly reduced at a concentration of 100 μg/ml compared to 50 μg/ml (P-value <0.05). Also, over time a significant decreasing trend in the viability of promastigotes confirmed the time-dependent manner of the fractions (P-value <0.01). Furthermore, F5 had the highest leishmanicidal activity at the first incubation time compared with other fractions.

Conclusion

Terpenoid-rich fractions of the P. abrotanoides have a leishmanicidal activity that depends on time and concentration. Among them, F5 has the highest potency that may contain potent terpenoid constituents.

LIVE-streaming 3D images: A neuroscience approach to full-body illusions

Inspired by recent technological advances in the gaming industry, we used capture cards to create and LIVE-stream high quality 3D-images. With this novel technique, we developed a real-life stereoscopic 3D full-body illusion paradigm (3D projection). Unlike previous versions of the full-body illusion that rely upon unwieldy head-mounted displays, this paradigm enables the unobstructed investigation of such illusions with neuroscience methods (e.g., transcranial direct current stimulation, transcranial magnetic stimulation, electroencephalography, and near-infrared spectroscopy) and examination of their neural underpinnings. This paper has three aims: (i) to provide a step-by-step guide on how to implement 3D LIVE-streaming, (ii) to explain how this can be used to create a full-body illusion paradigm; and (iii) to present evidence that documents the effectiveness of our methods (de Boer et al., 2020), including suggestions for potential applications. Particularly significant is the fact that 3D LIVE-streaming is not GPU-intensive and can easily be applied to any device or screen that can display 3D images (e.g., TV, tablet, mobile phone). Therefore, these methods also have potential future clinical and commercial benefits. 3D LIVE-streaming could be used to enhance future clinical observations or educational tools, or potentially guide medical interventions with real-time high-quality 3D images. Alternatively, our methods can be used in future rehabilitation programs to aid recovery from nervous system injury (e.g., spinal cord injury, brain damage, limb loss) or in therapies aimed at alleviating psychosis symptoms. Finally, 3D LIVE-streaming could set a new standard for immersive online gaming as well as augmenting online and mobile experiences (e.g., video chat, social sharing/events).

In Vitro and In Vivo Anti-Toxoplasma Activities of Dracocephalum kotschyi Extract in Experimental Models of Acute Toxoplasmosis

BACKGROUND

The problem of resistance to antiparasitic drugs, associated with their side effects, suggest exploring other alternatives, including medicinal plants. Dracocephalum kotschyi (D. kotschyi), for example, from Lamiaceae family, is a plant widely used in Iran and in many countries, and to which interesting pharmacological properties have been attributed. This study aimed to investigate in vitro and in vivo anti-Toxoplasma activities of D. kotschyi extract in experimental models of acute toxoplasmosis.

METHODS

Anti-Toxoplasma activity of the extracts in vitro was performed on Vero Cell, using the MTT test. Vero cell were infected with (3 × 10⁵ tachyzoites/well) following treatment with Dichloromethane (F1), dichloromethane: methanol (F2), methanol (F3), methanol: water (F4), and deionized water (F5) extracts of D. kotschyi, and pyrimethamine and sulfadiazine (positive control). MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was used to measure cell viability. Effects of extracts on tachyzoites viability were evaluated by trypan blue exclusion method, followed by light microscopy. For in vivo test, 18 groups of 8-10-week-old Inbred Balb/c mice weighing 18-20 g, were intraperitoneally infected with 2 × 10³ tachyzoites and then treated with sterile PBS (negative control), pyrimethamine (25 mg/kg) and sulfadiazine (500 mg/kg) as positive controls, and F1 to F5 extracts (at doses 50, 100 and 200 mg/kg).

RESULTS

The 50% Inhibitory Concentration of F1 extract, F2 extract, Sulfadiazine (Positive control) and Pyrimethamine (Positive control) were 8.77 µg, 7.1 µg 391.18 µg, and 84.20 µg, respectively, while the selectivity indices were 15.667, 30.197, 1.552 and 4.064, respectively. In vivo anti-Toxoplasma activity test showed that Methanol: water (F-4) 50 extract was more active than the positive control.

CONCLUSIONS

Indeed, the extract allowed a survival rate of 10% of the mice, compared to 0% for all the other groups. D. kotschyi has the potential to be valorized in the management of toxoplasmosis.

Effect of transgenic Leishmania major expressing mLLO-Bax-Smac fusion gene in the apoptosis of the infected macrophages

OBJECTIVES

Leishmaniasis is a complex infection against which no confirmed vaccine has been reported so far. Transgenic expression of proteins involved in macrophage apoptosis-like BAX through the parasite itself accelerates infected macrophage apoptosis and prevents Leishmania differentiation. So, in the present research, the impact of the transgenic Leishmania major including mLLO-BAX-SMAC proapoptotic proteins was assayed in macrophage apoptosis acceleration.

MATERIALS AND METHODS

The coding sequence mLLO-Bax-Smac was designed and integrated into the pLexyNeo2 plasmid. The designed sequence was inserted under the 18srRNA locus into the L. major genome using homologous recombination. Then, mLLO-BAX-SMAC expression was studied using the Western blot, and the transgenic parasite pathogenesis was investigated compared with wild-type L. major in vitro and also in vivo.

RESULTS

Western blot and PCR results approved mLLO-BAX-SMAC expression and proper integration of the mLLO-Bax-Smac fragment under the 18srRNA locus of L. major, respectively. The flow cytometry results revealed faster apoptosis of transgenic Leishmania-infected macrophages compared with wild-type parasite-infected macrophages. Also, the mild lesion with the less parasitic burden of the spleen was observed only in transgenic Leishmania-infected mice. The delayed progression of leishmaniasis was obtained in transgenic strain-injected mice after challenging with wild-type Leishmania.

CONCLUSION

This study recommended transgenic L. major including mLLO-BAX-SMAC construct as a pilot model for providing a protective vaccine against leishmaniasis.

Evaluation of the Anti-Leishmanial Effect of Recombinant Clostridium α-Toxin

BACKGROUND

Leishmaniasis is an infectious disease common in tropical and subtropical regions caused by the genus Leishmania, which is transmitted by the bite of female sandflies. In this study, we evaluate the anti-leishmanial effect of recombinant Clostridium α-toxin protein alone and the combination with glucantime through in vitro and in vivo.

MATERIALS AND METHODS

Production, expression, and purification of recombinant α-toxin were evaluated by SDS-PAGE and Western blotting techniques. The antileishmanial activities of the purified α-toxin plus and without glucantime were examined in vitro and in vivo.

RESULTS

The results indicated successful expression of α-toxin as a 48 kDa band on SDS-PAGE and Western blot methods. Also, evaluation of α-toxin IC50 showed the strong fatal effect of it, and glucantime on medium proliferated Leishmania promastigotes at lower concentrations compared with glucantime or α-toxin alone. Moreover, in vivo surveys showed that at the end of treatment courses, the mean of lesion size diminished in glucantime plus α-toxin treated mice versus negative control groups (p < 0.001). Also, there was a significant difference in the parasite burden of the spleen and liver of the control versus the test groups (p < 0.001).

CONCLUSION

The results showed recombinant α-toxin has synergistic effects with glucantime in destroying Leishmania parasites.

Study of therapeutic effect of different concentrations of imatinib on Balb/c model of cutaneous leishmaniasis

Leishmaniasis, as a tropical and subtropical disease, is endemic in more than 90 countries around the world. Today, cutaneous leishmaniasis (CL) that affects more than 1.5 million people per year lacks a definitive treatment approach. Imatinib is an anticancer drug that inhibits the abnormal function of Bcr-Abl due to its tyrosine kinase inhibitor, and that was the reason why the drug was tested for CL treatment because protein kinases are essential enzymes in the Leishmania genus. In this study, the L. major CL model of Balb/c mice was produced by injection of the cultured metacyclic form of parasite at the base of the tail. The possible recovery of CL ulcers and determination of the optimum dose of imatinib against Leishmania amastigotes were evaluated. A significant decrease was observed in mice treated with amphotericin B (positive control group) as well as imatinib 50 mg/kg compared to the unreceived drug, negative control group (P<0.05). This study could be promising in gaining insight into the potential of imatinib as an effective treatment approach against CL.

Color properties of artificial white spot lesions treated by experimental resin infiltrants containing bioactive glass and nano-fluorohydroxyapatite

AIM

This study was conducted to assess the masking effects of some experimental resin infiltrants containing bioactive glass (BAG) and nano-fluorohydroxyapatite (n-FHAP) on enamel white spot lesions (WSLs).

MATERIALS AND METHODS

Fifty enamel specimens were embedded in an acrylic resin and divided into five groups (n = 10). After creating artificial enamel lesions, the specimens were infiltrated by the following resins: 1) Group 1 (T/control group): TEG-DMA; 2) Group 2 (T2H): TEG-DMA + 2 wt% n-FHAP; 3) Group 3 (T5H): TEG-DMA + 5 wt% n-FHAP; Group 4 (T2B): TEG-DMA + 2 wt% BAG; Group 5 (T5B): TEG-DMA + 5 wt% BAG. Next, the specimens were subjected to demineralization-remineralization cycles for 2 weeks. Color assessments were performed by a spectrophotometer in four distinct stages: baseline, after the production of artificial caries, after resin infiltration, and 2 weeks after resin infiltration. L*, a*, b*, and ΔE values were calculated at each stage. Color parameters were analyzed statistically using the Kruskal-Wallis and Mann-Whitney U tests. The significance level was set at 5%.

RESULTS

All treatments led to a decrease in the L3* compared with the L2* value. The resin infiltrant containing 5% fluorohydroxyapatite (FHAP) exerted the highest L* reduction effect among all the groups. The T group was the only resin infiltrant group with a lower mean of a4* than those compared at baseline. Regarding the ΔE13* and ΔE14* values, only the resin infiltrants of groups 1 (T), 2 (T2H), and 3 (T5H) were able to mask artificial caries.

CONCLUSION

Experimental resin infiltrants containing n-FHAP were able to mask WSLs after 14 days.

Evaluation of Different Concentrations of Imatinib on the Viability of Leishmania major: An In Vitro Study

BACKGROUND

Leishmaniasis is an infectious disease caused by an intracellular parasite of Leishmania and is transmitted through the female sandflies bite and may lead to severe skin lesions. Although drugs such as antimony compounds are available, their side effects such as toxicity, low efficacy, and emergence of resistance have raised the importance of effective replacement. Imatinib, as an inhibitor of tyrosine kinase (TK) of Leishmania, stops abnormal function of TK such as Bcr-Abl through assembling into transmembrane pores in a sterol-dependent manner. Hence, the evaluation of killing effects of different concentrations of imatinib against Leishmania major amastigotes and promastigotes in vitro were the objectives of the present study.

MATERIALS AND METHODS

The killing effects of different concentrations of imatinib (25, 50, and 100 μg) and 25 μg amphotericin B (as positive control) were evaluated against RPMI 1640-cultured promastigotes and the amastigote/macrophage model by MTS cell proliferation assay kit (ab197010) and Giemsa staining method during 24, 48, and 72 h.

RESULTS

The results showed anti-Leishmania effect of imatinib in concentration and time-dependent manner. The lowest number of live promastigotes and amastigotes were obtained due to treat with 100 μg/ml imatinib at 72 h. Furthermore, 100 μg concentration of imatinib had the same effect as 25 μg amphotericin B on both L. major promastigotes and amastigotes (P < 0.001).

CONCLUSION

The anti-Leishmania effect of imatinib was confirmed by MTS and direct microscopy. Further study is recommended for evaluating possible therapeutic effects of imatinib on leishmaniasis in vivo.

Effect of CO2 Laser on the Prevention of White Spot Lesions During Fixed Orthodontic Treatment: A Randomized Clinical Trial

Objective

This study aimed to assess the effect of carbon dioxide (CO2) laser on prevention of white spot lesions (WSLs) associated with fixed orthodontic treatment.

Methods

In this parallel controlled trial, 554 maxillary anterior teeth in 95 patients with age range of 12-30 years were included. The samples were randomly divided in two groups: 1) CO2 laser (n=278) and 2) control (n=276) groups. Following bracket attachment, the teeth in the laser group were exposed to CO2 laser (0.4 mw, 10.6 μm, 5 Hz) for 20 s, and the control group received placebo light. Incidence, severity, and extent of the lesions were assessed in four surface regions (gingival, incisal, mesial, and distal) at baseline and 6 months post-irradiation. The inter-group comparison was performed by the Mann-Whitney U test and McNemar analysis.

Results

A significant difference regarding WSLs incidence in all teeth was observed between the two study groups (p<0.001). The two study groups illustrated a significant difference in lesion extent and incidence in incisal, mesial, and distal regions (p<0.05). The WSLs were significantly different in terms of severity in the incisal and mesial sites (p<0.05).

Conclusion

The CO2 laser irradiation seemed to effectively prevent incidence of WSLs. In addition, its effectiveness varied depending on the surface region.

The Rate of Demineralization in the Teeth Prepared by Bur and Er:YAG Laser

Introduction: The present in vitro study evaluated the recurrence rate of caries following cavity preparations with bur (conventional technique) and irradiation by Erbium:Yttrium- Aluminum-Garnet (Er:YAG) laser through micro hardness test. Methods: A total of 72 human extracted molars were randomly divided into 3 groups and class 5 cavities were prepared on them with 3 different methods: G1) conventional bur, G2) Er:YAG laser irradiation alone and G3) laser irradiation + laser treatment. The specimens were immersed in the artificial caries solution with pH of 2.0 and 5.0 (12 days) and then immersed in re-mineralizing solution with pH of 7.0 (25 days). The specimens were longitudinally sectioned and their Vickers micro hardness was determined. Data were statistically analyzed by means of three-way analysis of variance (ANOVA) and Tukey multiple comparisons tests. Results: The micro hardness of the samples was affected by substrate type (enamel and dentin) and low values were achieved in dentin (P<0.001). Moreover, no significant difference was observed between preparation methods by bar and laser irradiation alone (P ≤0.499). Although laser irradiation + laser treatment decreased micro hardness of enamel compared to other methods. In dentin samples, different methods of preparation showed no significant effect on micro hardness (P ≤0.874). Conclusion: Due to the similar values of micro hardness following G1 and G2, it seems that Er:YAG laser alone is as much effective as the conventional bur to prevent recurrence caries. However, because of the high prices of laser instruments, bur preparations can be done commonly.

SEROPREVALENCE OF TOXOPLASMA GONDII INFECTION AMONG PATIENTS ADMITTED TO AL-ZAHRA HOSPITAL, ISFAHAN, IRAN

BACKGROUND

Toxoplasma gondii (T. gondii) infection is one of the most common parasitic infections among humans and other warm-blooded animals worldwide. The aim of this study was to evaluate toxoplasmosis status in patients admitted to Al-Zahra hospital, Isfahan, Iran.

METHODS

This cross-sectional study was conducted from October 2012 to January 2015. During this period, 716 patients referred to AI-Zahra hospital in Isfahan city, Iran, were studied to investigate the IgG and IgM antibodies against T. gondii using ELISA kit. The data were analysed by Chi-square and Fisher's exact tests. In addition, the relation of data with age and sex were also examined.

RESULTS

Among 716 patients, 21 patients (2.9%) had positive IgM and 288 patients (40.2%) had positive IgG titer against T. gondii. Data analysis by Chi-square and Fisher's exact tests revealed that there was no significant relationship between IgG titer and age (p > 0.05). Additionally, there was no relationship between IgM titer and age (p > 0.05). The data showed that there was no relationship between IgG and IgM antibody titer and sex (p > 0.05).

CONCLUSION

The prevalence of toxoplasmosis in Isfahan inhabitants seems fairly high but it can be concluded that the rate of seropositive patient is moderate comparing to other regions of country. Accordingly, the authors propose that all sensitive patients have to be tested for T. gondii antibody in order to prevent the consequences of disease.

Shear bond strength of the repair composite resin to zirconia ceramic by different surface treatment

INTRODUCTION

The purpose of this study is the evaluation of the amount of surface roughness (Ra) of Zirconia Ceramic following different surface treatments as well as the assessment of its shear bond strength to composite resin.

METHODS

40 sintered zirconia ceramic block samples were randomly divided in 4 groups of 10 and underwent the following surface treatments: a) Control group without treatment b) Air abrasion with Al2O3 particles (50um) c) Er:YAG laser with 2W power for 10s d) Nd:YAG laser with 1.5W power for 2min Then the mean surface roughness (Ra) was evaluated by profilometer. In the next step, Alloy primer was used on a section of 9mm(2) on the samples following the manufacturer's instructions. After that Clearfil AP-X composite resin in cylinder shape with an internal diameter and height of 3mm were cured on the sections mentioned. At the end, all samples were tested to assess the shear bond strength by the Universal Testing Machine at a speed of 0.5mm/min until fracture occurred. The mean shear bond strengths were calculated and statistically analyzed by One Way ANOVA.

RESULTS

ANOVA analysis showed that roughness (Ra) was significantly different between the groups (P≤0.05). Ra was higher in the Nd:YAG group compared to the other groups (P≤0.05). The lower Ra was related to the control group. Air abrasion group showed highest amounts of shear bond strength and Nd:YAG laser group demonstrated lower amounts of shear bond strength (P≤0.05).

CONCLUSION

Various surface treatments are differently effective on bond strength. Air abrasion is the most effective method to condition zirconia ceramic surfaces.

Macrodontia in association with a contrasting character microdontia

The dental, genetic, radiological and dermatoglyphic findings of a 19-year-old girl showing macrodontia of maxillary permanent central incisors in association with a contrasting character, microdontia of maxillary permanent lateral and mandibular primary central incisors and bilateral absence of maxillary first premolars and missing of the right mandibular second premolar and peg-shaped mandibular primary lateral incisors and canines were presented.

Taurodontism in association with supernumerary teeth

The dental, radiological, genetic and dermatoglyphic findings of an additional patient with taurodontism in association with supernumerary teeth were presented and the findings of the patient were compared with those in the literature.

Local, hypoplastic type of amelogenesis imperfecta: a clinical, genetic, radiological and dermatoglyphic study

A patient and her family members showing X-linked dominant form local, hypoplastic type of amelogenesis imperfecta (AI) were investigated from view-point of their teeth, clinical, genetic, radiological and particularly dermatoglyphic findings. It was suggested that it might be a close relationship between the intra-uterine development of both AI and unusual dermatoglyphs originated from the same layer, ectoderm and an X-linked dominant gene could determine both abnormal teeth and unusual dermatoglyphic characteristics in questions.